Resistant Cells Research Articles

Abstract PO4-24-09: Grape seed extract inhibits EGFR signaling pathway as a main factor of tamoxifen resistant in hormone receptor positive breast cancer

Abstract Purpose Because more than 60% of breast cancers are hormone-receptor (HR) positive, endocrine therapy plays an important role. Tamoxifen is an antagonist of estrogen receptor-α and main treatment drug for HR-positive breast cancers. However, efficacy is not satisfactory because of the development of resistance. EGFR expression was associated with poor prognosis in HR-positive breast cancers. Loss of ER by EGFR activation induced tamoxifen resistance. And extracellular signal-regulated kinase (ERK) is another important factor for tamoxifen resistance. Activation of ERK signaling in breast cancer is not only associated with augmented tumor growth and metastasis but also with tamoxifen resistance. Therefore, the inhibition of ERK/EGFR signaling associated with tamoxifen resistance could improve the survival rate. Grape seed extract (GSE) is which contains a high content of flavonoid polyphenolic compounds. GSE is known to have various pharmacological effects, including antioxidant, anti-inflammatory, antitumor activity. In this study, we explored the activity of GSE in tamoxifen resistant breast cancer cells by inhibiting EGFR signaling pathway. Method We examined the suppressive effect of GSE on various signaling pathways. To confirm the pharmacological activity of GSE, we treated EGFR positive breast cancer cells with GSE. Levels of mRNA and protein expression were analyzed by real-time PCR and western blot. And cell proliferation and invasiveness were analyzed by the colony-forming assay and the Boyden chamber assay. Results 1. GSE down regulates EGFR and ERK in EGFR positive breast cancer cell line. The cells were treated with the indicated concentrations GSE for 48 hrs. The levels of p- and t-ERK and t-EGFR were measured through Western blotting. The levels of phosphorylated EGFR and ERK were decreased by GSE at the indicated doses for 48hrs. 2. EGF, a ligand of EGFR, upregulates the MMP-9 and GSE suppresses MMP-9. Matrix metalloproteinase-2 (MMP-2) and matrix metalloproteinase-9 (MMP-9) are upregulated in most cancers and play crucial roles in modulating invasion and metastasis. EGFR with its ligand epidermal growth factor (EGF) regulates Matrix metalloproteinase-2 (MMP-2) and matrix metalloproteinase-9 (MMP-9). After treating EGFR positive breast cancer cells with EGF and TGF, MMP-9 levels were increased. However, MMP-9 level was decreased with GSE as indicated doses for 48hrs. Conclusion Taken together, GSE inhibited the ERK/EGFR and EGF/MMP-9 signaling pathway in EGFR positive breast cancer cells. Therefore, we propose the possibility of GSE as an effective adjuvant for tamoxifen resistant breast cancer. Citation Format: Seung Pil Jung, Eun-Shin Lee, Ji Young You, Jung Hwa Chun, Hyunyou Kim. Grape seed extract inhibits EGFR signaling pathway as a main factor of tamoxifen resistant in hormone receptor positive breast cancer [abstract]. In: Proceedings of the 2023 San Antonio Breast Cancer Symposium; 2023 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2024;84(9 Suppl):Abstract nr PO4-24-09.

Abstract PO3-28-12: Targeting the KCa3.1 potassium channel arrests ER+ breast cancer growth and re-sensitizes to drug resistance

Abstract Standard of care for breast cancer (BC) treatment including Selective-Estrogen Receptor (ER)-modulators and/or degraders (SERM; tamoxifen, SERD;Fulvestrant) or cyclin-dependent kinases CDK4 and CDK6 (palbociclib) can be effective therapeutic strategies. However, drug toxicity and/or drug resistance severely limit these approaches and patients succumb to the disease. Therefore, there is an urge to develop new therapeutic strategies against ER+-BC. Ion channels are general pharmacological targets however, little is known about the role of this class of proteins in cancer biology. We discovered that expression of the KCa3.1 potassium ion channel is downregulated in ER+-BC. Also, patients expressing high level of KCa3.1 present a better overall survival (OS) and relapse free survival when compared with patients with low expression. Thus, these data indicate that KCa3.1 is a prognostic factor in ER+-BC and that high activity of this channel plays a fundamental role in an oncosuppressor signature. Our central hypothesis is that pharmacological targeting KCa3.1 with activator molecules arrests growth of ER+-BC. We discovered that ER+-BC patient-derived organoids (PDO) and cell lines treated with KCa3.1 agonists including the FDA approved Chlorzoxazone, (CZX) arrests significantly inhibit tumor growth. Activation of KCa3.1 arrested the cell cycle in the G0/G1 phase by activating a senescent-like phenotype. Furthermore, our studies on the biochemical signaling that underlines this event demonstrated that increased expression level of KCa3.1 protein associated with lower expression level of ERa in a cell cycle phase-dependent manner. Furthermore, use of KCa3.1activator produced a proteasomal-dependent ERa degradation. To better characterize the therapeutic benefit of targeting the KCa3.1, we assessed the effects of CZX on developed several tamoxifen and/or palbociclib resistant cell lines and PDO models. We found that the combination of CZX strongly potentiated the lethal effects of both tamoxifen and palbociclib in the relative resistant models. We conclude that pharmacological targeting KCa3.1 potassium channel in ER+-BC can be considered a novel, safe and efficacious therapeutic strategy. Citation Format: Davide Delisi, Metin Cetin, Ozge Saatci, Ozgur Sahin, Saverio Gentile. Targeting the KCa3.1 potassium channel arrests ER+ breast cancer growth and re-sensitizes to drug resistance [abstract]. In: Proceedings of the 2023 San Antonio Breast Cancer Symposium; 2023 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2024;84(9 Suppl):Abstract nr PO3-28-12.

Abstract PO3-14-05: Integration of metabolomics and transcriptomics to Reveal Potential Biomarkers Associated with Treatment Response of Neoadjuvant Therapy in HER2+ Breast Cancer

Abstract Background: Neoadjuvant therapy (NAT) has become the standard treatment for early human epidermal growth factor receptor 2 positive (HER2+) breast cancer. For patients with HER2+ breast cancer, achieving a pathologic complete response (pCR) is highly indicative of their prognosis. However, not all HER2+ breast cancer patients could benefit from the NAT, about 40%-50% patients could not achieve pCR at surgery, even if they used the present standard neoadjuvant regime of TCbHP (taxane, carboplatin, trastuzumab and pertuzumab). This study was conducted to explore potential indicators associated with neoadjuvant efficacy of TCbHP in HER2+ breast cancer. Methods: Consecutive HER2+ breast cancer patients, who received and completed NAT with TCbHP regime and subsequent surgery at Chongqing University Cancer Hospital were prospectively enrolled. LC-MS and GC-MS platform-based untargeted metabolomics were performed to determine the metabolic profiles of plasma samples from these patients at different time points during treatment period. Random forest (RF) was used to establish predictive models based on pre-therapeutic metabolic traits. The potential monitors for the treatment response were obtained by time series analysis. Transcriptome analysis was performed in available samples to identify differentially expressed genes (DEGs) before treatment. qRT-pCR was used to detect DEGs in tastuzumab-sensitive and -resistant cell lines. Metabolic and transcriptomic data were integrated to explore substantially altered pathways that might be responsible for drug resistance. Results: From July 20, 2020 to May 28, 2021, a total of 40 HER2+ breast cancer patients with 120 plasma samples were eligible and recruited for this study. Of whom 21 (52.5%) patients achieved pCR and 19 (47.5%) achieved non-pCR, there are no significant difference in baseline clinicopathological features between pCR and non-pCR patients. There were significant differences in plasma metabolic profiles between non-pCR and pCR groups before and during treatment. A total of 100 differential metabolites were identified between pCR and non-pCR patients at pre-therapeutic period, which were markedly enriched in 40 metabolic pathways. Four key metabolites [sophorose, N-(2-acetamido)iminodiacetic acid, taurine and 6-hydroxy-2-aminohexanoic acid] were selected by RF analysis. The AUC value to discriminate pCR and non-PCR group to NAT of the single potential metabolite or combined panel of these metabolites were more than 0.910. 18 metabolites exhibit a potential for monitoring efficacy. Among 163 DEGs identified by RNA-seq, some genes might associate with trastuzumab resistance detected by qRT-PCR in cell lines. 39 altered pathways were found abnormally expressed at both the transcriptional and metabolic levels, including ABC transporters, protein digestion and absorption, mineral absorption, et al. Conclusion: By metabolomics analysis, we have both offered a road map of the molecular alterations underlying NAT of TCbHP regime in HER2+ breast cancer and a preliminary analysis of a unique metabolic signature that might be used to distinguish non-pCR from pCR patients. Metabolomics integrated with transcriptomics analysis could assist for gaining new insights into biochemical pathophysiology and might facilitate the development of new treatment targets for insensitive patients. Citation Format: Ningning Zhang, Yuxin Huang, Guanwen Wang, Yimei Xiang, Zhouhong Jing, Junjie Zeng, Feng Yu, Xianjun Pan, Wenqi Zhou, Xiaohua Zeng. Integration of metabolomics and transcriptomics to Reveal Potential Biomarkers Associated with Treatment Response of Neoadjuvant Therapy in HER2+ Breast Cancer [abstract]. In: Proceedings of the 2023 San Antonio Breast Cancer Symposium; 2023 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2024;84(9 Suppl):Abstract nr PO3-14-05.

Abstract PO2-14-10: A selective MCL-1 inhibitor AZD5991 showed tumor regression in a triple-negative inflammatory breast cancer xenograft model

Abstract Background Triple-negative breast cancer (TNBC) accounts for 15-20% of all breast cancer diagnoses but up to 30% of breast cancer-related deaths. Similarly, Inflammatory breast cancer (IBC) accounts for 2-4% of breast cancer diagnosis but causes 8%–10% of all breast cancer-related deaths. The myeloid cell leukemia-1 (MCL-1) is a member of the BCL-2 family of proteins, which is highly amplified in numerous human cancers and associated with cell immortalization, transformation, and chemoresistance. In fact, MCL-1 is amplified in 55% of TNBC after preoperative chemotherapy. Amongst the MCL-1 inhibitors that have been developed, AZD5991 showed high selectivity and affinity for MCL-1. In myeloma and acute myeloid leukemia cells AZD5991 induces apoptosis and showed anti-tumor effects in in vivo models. In the present study, we evaluated the biological role of the MCL-1 inhibitor AZD5991 in IBC and TNBC in vitro and in vivo models. Materials and methods The expression of the MCL-1 gene was analyzed in the World Consortium IBC patient dataset. Next, we screened a panel of TNBC and IBC cell lines for MCL-1 expression by western blot analysis. The effect of AZD5991 on TNBC and IBC cells was analyzed via cell titer-blue proliferation, clonogenic assays and soft agar assay. To further validate these findings, we used siRNA to knockdown MCL-1 and performed cell proliferation, clonogenic and migration assays. To identify signaling pathways involved in MCL-1 Inhibitor’s effects we performed a proteome profiler human apoptosis array in TNBC cells in the presence of AZD5991. The anti-tumor effect of the MCL-1 inhibitor was evaluated using a SUM-149 (TN-IBC) orthotopic xenograft mouse model. The mice were treated with AZD5991 at doses of 15 and 30mg/kg once weekly via tail vein injection for a duration of 4 weeks. Results The mean expression level of MCL-1 was higher in patients with TNBC than in those with non-TNBC. Further, compared to the patients with ER positive, HER-2 negative tumors those with TNBC showed an increased in the mean expression of MCL-1 gene (p value= 0.05). We screened a panel of TNBC and IBC cell lines in which most of the cell lines showed high levels of MCL-1. The cell proliferation assay showed IC50 ranging from 0.27 – 19.6 μM. The SUM149, SUM190, FCIBC02, MDA-IBC3 and MDA-MB-468 cells showed high sensitivity and showed significant decrease in the proliferation rate while BCX010, KPL4, MDA-MB-231, 4T1.2 and E0771 cells as well as the normal breast cells MCF10A exhibited resistance with no significant decrease in proliferation. The clonogenic and soft agar assays with these sensitive and resistant cell lines showed similar results. Further, these findings were validated via genetic knockdown of MCL-1 which resulted in a significant decrease in cell proliferation, colony formation and migration capability of the TNBC cells. To identify signaling pathways involved in MCL-1 Inhibitor’s phenotypic changes, we performed a proteome profiler human apoptosis array which showed a decreased in BCLx expression, and an increase in expression of BAX and phospho-Rad17 proteins in the AZD5991 treated TN-IBC cells. Finally, in a SUM-149 (TN-IBC) orthotopic xenograft mouse model, mice injected with 30mg/kg showed a significant tumor regression compared to the vehicle-treated mice (vehicle vs 30 mg/kg, p value=0.0006). Conclusions and Future directions Our data demonstrates that AZD5991 inhibits tumorigenesis in an inflammatory breast cancer xenograft model. We are currently validating several significant targets to understand the biological mechanisms related to our candidate drug. Our long-term goal is to develop MCL-1 targeted therapy in combination with standard-of-care treatment for inflammatory and triple-negative breast cancers. Citation Format: Mohd Mughees, Moises Tacam, Alex Tan, Michael White, Bisrat Debeb, Emilly Villodre, Xiaoding Hu, Debu Tripathy, Wendy Woodward, Rachel Layman, Geoffrey Bartholomeusz, Chandra Bartholomeusz. A selective MCL-1 inhibitor AZD5991 showed tumor regression in a triple-negative inflammatory breast cancer xenograft model [abstract]. In: Proceedings of the 2023 San Antonio Breast Cancer Symposium; 2023 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2024;84(9 Suppl):Abstract nr PO2-14-10.

Abstract PO4-23-10: Restoring the efficacy of standard of care in treatment-refractory ER+ breast cancer by re-activation of cAMP-ROS-DNA damage axis

Abstract Estrogen receptor (ER)-positive (ER+) breast cancer has the highest incidence rate and accounts for around 75% of all cases. Endocrine therapy has been the mainstay therapy for the treatment of both early and late-stage ER+ breast cancer for decades. Although most ER+ breast cancer patients initially respond well to endocrine therapy, resistance is common. The addition of CDK4/6 inhibitors to endocrine therapy led to significant improvements in clinical outcome, and they are now considered one of the standard of care (SOC) therapies. However, a significant proportion of patients still suffer from disease relapse upon prolonged use of endocrine therapy in combination with CDK4/6 inhibitors, representing a major clinical challenge that reduces the long-term benefit and patient survival. Therefore, elucidating the mechanisms of sensitivity and resistance to SOC therapy and identifying novel actionable targets are urgently needed. Here, we show that endocrine therapies and CDK4/6 inhibitors cause toxic PARP1 trapping and generation of a functional BRCAness phenotype by downregulating key DNA repair proteins that ultimately result in increased histone parylation and reduced H3K9 acetylation, leading to transcriptional blockage and cell death. Mechanistically, we found that SOC therapy downregulates phosphodiesterase 4D (PDE4D), resulting in increased cAMP levels, PKA-dependent phosphorylation of mitochondrial COXIV-I, generation of mitochondrial reactive oxygen species (ROS), and DNA damage. Importantly, we identified PDE4D as a novel ER target gene that in turn stimulates ER activity in a feedforward loop in endocrine-responsive models and regulates BRCA1 expression. However, during SOC resistance, an ER-to-EGFR switch induces PDE4D overexpression via c-Jun. Inhibition of PDE4D using BPN14770, the first-in-class PDE4D allosteric inhibitor that has successfully completed Phase II trials in Fragile X syndrome, or its upstream EGFR in combination with SOC therapies in drug-resistant settings, including multiple acquired SOC resistant cell line models, primary cultures and organoids of endocrine resistant ER+ PDXs reinstates PARP1 trapping and BRCAness, leading to drug sensitization in vitro and in vivo. Notably, we demonstrated that high PDE4D mRNA and protein expression is associated with dramatically worse disease-free survival and overall survival in endocrine therapy-treated ER+ breast cancer. Considering the availability of potent and non-toxic PDE4D inhibitors, clinically approved EGFR and PARP1 inhibitors, our findings have great translational potential. Citation Format: Ozge Saatci, Metin Cetin, Meral Uner, Unal Metin Tokat, Ioulia Chatzistamou, Pelin Gulizar Ersan, Elodie Montaudon, Aytekin Akyol, Sercan Aksoy, Aysegul Uner, Elisabetta Marangoni, Sajish Mathew, Ozgur Sahin. Restoring the efficacy of standard of care in treatment-refractory ER+ breast cancer by re-activation of cAMP-ROS-DNA damage axis [abstract]. In: Proceedings of the 2023 San Antonio Breast Cancer Symposium; 2023 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2024;84(9 Suppl):Abstract nr PO4-23-10.

Abstract PO1-23-10: Multi-omics analysis identifies the mechanism in cross-resistance to endocrine therapy and CDK4/6 inhibitor in breast cancer

Abstract Background In advanced/metastatic breast cancer (MBC) or recurrent breast cancer on prior endocrine therapy (ET), selective estrogen receptor downregulator (SERD) of fulvestrant and CDK4/6i are the mainstream therapy regimen. In the clinical, fulvestrant combined with CDK4/6i is the second-line therapy for breast cancer (BC) that had progressed during previous endocrine therapy. The alternation of backbone from aromatase inhibitor or tamoxifen (endocrine sensitive) to fulvestrant (endocrine resistance) partially comes from the mechanism of ET resistance. Moreover, in the PALOMA-2 trial, approximately 30% of patients developed into recurrence after two years of CDK4/6i treatment, indicating that the ET backbone may affect CDK4/6i efficacy, bringing an emerging clinical issue of cross-resistance. However, whether the cross-resistance of ET would be more sensitive to CDK4/6i or impair the efficacy of CDK4/6i is still an ambiguous and heterogeneous issue. Also, in CDK4/6i resistance, whether the mechanism of ET resistance is associated with the dysregulation of the cell cycle or activation of other “bypass” signaling pathways is not fully understood. Methods We use a 3D and 2D culture of ET-sensitive cell S0.5, tamoxifen-resistant cell TAM, and fulvestrant-resistant cell 182R6 as our model. The 3D culture was performed by using the Tools 3d culture plus kit. Drug responses to fulvestrant and ribociclib were conducted by using CCK-8 assay. The potential target and pathway involved in the mechanisms of cross-resistance were analyzed by using multi-omics analysis of sequential window acquisition of all theoretical mass spectra (SWATH-MS), RNA-seq, micro-western array (MWA), traditional western blots, and open access database. Results In comparison with S0.5, the sensitivity to fulvestrant was indeed reduced in 182R6 cell; however, we found the sensitivity to ribociclib was also reduced in 182R6 cell, which was in contrast to the ribociclib-sensitive TAM cell. The different response to ribociclib between 182R6 and TAM, indicating that cross-resistance between fulvestrant and ribociclib existed in the model of 182R6 and TAM would be another control for 182R6 to find the target with or without cross-resistance. With multi-omics analysis of SWATH-MS, RNA-seq, MWA, western blots, and open access database, we found some unique or high expression of targets and pathways including EGFR, HER2, CDK6, CDK2, MAPK, and TNF-α pathways in cross-resistance R6 cell than in parental and TAM cell. We reconfirmed the above targets by 3D culture and found MAPK signaling pathway of p-ERK was not affected under ribociclib treatment, indicating the important role of the MAPK signaling pathway in ribociclib resistance. Conclusion To our knowledge, these results provide the first preliminary mechanism of cross-resistance between fulvestrant and ribociclib. We found fulvestrant resistant cell R6 exhibited the phenomenon of cross-resistance to ribociclib, which was in contrast to ribociclib-sensitive TAM cell. We also found some unique or high expression of target and pathway in cross-resistance R6 cells than in parental and TAM cells. In the future, with compound library screening and in vivo animal models, we expect to discover an FDA-approved drug or potential compound to overcome the cross-resistance between fulvestrant and ribociclib. Citation Format: Ming-Feng Hou, Chung-Liang Li, Chih-Po Chiang. Multi-omics analysis identifies the mechanism in cross-resistance to endocrine therapy and CDK4/6 inhibitor in breast cancer [abstract]. In: Proceedings of the 2023 San Antonio Breast Cancer Symposium; 2023 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2024;84(9 Suppl):Abstract nr PO1-23-10.

Abstract PO5-18-07: A Humanized Monoclonal Antibody to Secreted Frizzled-Related Protein 2 Inhibits TNBC Lung Metastases

Abstract Introduction: A promising novel target for breast cancer is secreted frizzled-related protein 2 (SFRP2). SFRP2 protects tumors against apoptosis, promotes T-cell exhaustion, and induces angiogenesis. SFRP2 is expressed in breast cancer but has not been specifically evaluated in triple negative breast cancer. We previously developed a humanized monoclonal antibody to SFRP2, (hSFRP2 mAb) that inhibits primary breast cancer growth in mice without toxicity. The purpose of this study is to establish the presence of SFRP2 in human TNBC, evaluate the efficacy of hSFRP2 mAb in metastatic TNBC in vivo, and in a cell line resistant to chemotherapy. Methods: Immunohistochemistry (IHC) with SFRP2 antibody on a human TNBC tissue microarray (TMA) containing 88 FFPE cores. After IHC with primary antibody to SFRP2, the TMA was scanned and staining intensity was quantified using spatial analysis. Results for SFRP2 staining were analyzed as previously described for analyses of estrogen and progesterone receptor positivity; categories are: 0-absence of staining; low positive (0-10%), and positive >10%. Development of a doxorubicin (dox)-resistant cell line and induction of apoptosis with hSFRP2 mAb. MDA-MB-231 cells were treated with 4nM dox and increased 2nM at a time until the cells were resistant to 10µM dox after 12 months. WT and dox-resistant cells were treated for 4 hours with either hSFRP2 mAb (10uM,) or IgG control (10uM) (n=6). Apoptosis was detected with Promokine Apoptosis/Necrosis/Healthy cells kit. Cells were imaged using the EVOS FLc and counted using Imagej software. Differences between treated and control were compared with two-tailed T-test. hSFRP2 mAb treatment of mice with metastatic TNBC. PY8119 and E0771 TNBC murine cells (5 × 105/100 μL) were injected iv into 6–8-week-old C57BL/6 female mice. The next day the mice were treated with IgG1 control 8 mg/kg iv or hSFRP2 mAb 8 mg/kg iv every 3 days. After four weeks, the lungs were resected, and surface metastases were counted. Differences between treated and control were compared with Poisson distributions. FFPE sections of lungs were stained with ApopTag kit. Three metastases per lung were counted at 20 X, and the difference between IgG1 and hSFRP2 mAb groups compared with two-tailed T-test. Results: SFRP2 protein is present in human TNBC. Out of 88 cores, 83 cores (94%) were positive, 4 cores (4.5%) were minimally positive, and 1 core (1.1%) was negative for SFRP2. Development of a doxorubicin (dox)-resistant cell line and induction of apoptosis with hSFRP2 mAb treatment in vitro. The number of apoptotic cells in IgG1 control-treated MDA-MB-231 cells was 11.5 ± 3.7, and 76.6 ± 5.0 for hSFRP2 mAb-treated tumors (p< 0.001, n=9). The mean number of apoptotic MDA-MB-231 dox-resistant cells in IgG1 control was 16.7 ± 6.0, and 68.4 ± 6.4 for hSFRP2 mAb-treated tumors, (p< 0.001, n=9). hSFRP2 mAb inhibits the growth of metastatic TNBC in vivo and increases apoptosis. For E0771, the number of surface metastases was 8.9 ±2.8 in the IgG1 control group and 4.9 ± 1.1 in the hSFRP2 mAb treated group (p< 0.05, n=15). The number of apoptotic cells/HPF was 9.8 ± 1.8 for the IgG1 control group and 21.0 ± 4.6 for the hSFRP2 mAb group (n=15, p< .01). For Py8119 tumors there were 6.4 ± 1.0 metastases in the IgG1 control group and 3.6 ± 0.9 in the hSFRP2 mAb group (p< 0.05, n=11). The number of apoptotic cells/HPF was 6 ± 1.8 for the IgG1 control group and 14 ±1.3 for the hSFRP2 mAb group (n=10, p< 0.001). Conclusions: SFRP2 protein is abundantly expressed in human TNBC. A humanized monoclonal antibody to SFRP2 reduces TNBC lung metastases growth in two in vivo models and increases tumor apoptosis. TNBC resistant to doxorubicin remains sensitive to apoptosis induced by the hSFRP2 mAb. Citation Format: Lillian Hsu, Patrick Nasarre, Julie Siegel, Eleanor Hilliard, Rupak Mukherjee, Nancy Klauber-Demore. A Humanized Monoclonal Antibody to Secreted Frizzled-Related Protein 2 Inhibits TNBC Lung Metastases [abstract]. In: Proceedings of the 2023 San Antonio Breast Cancer Symposium; 2023 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2024;84(9 Suppl):Abstract nr PO5-18-07.

Abstract PO5-27-09: Pharmacological eIF4E inhibition suppresses anti-tumor activity in ER+ breast cancer

Abstract Elevated levels of eukaryotic initiation factor 4E (eIF4E) are found in a broad range of cancers, including breast, and have been associated with aggressive, drug resistant tumors. Furthermore, elevated eIF4E activity is sufficient to cause transformation in various cancers, while inhibition suppresses tumor growth. eIF4E, the main regulator and rate limiting factor of protein synthesis, is the downstream integrator of several important oncogenic signaling pathways (PI3K/AKT/mTOR, Ras/Raf/MEK, and Myc). Activation of eIF4E results in increased protein levels of key proliferation and metabolism proteins such as Cyclin D1 (CCND1) and Ornithine Decarboxylase 1 (ODC1), as well as an overall increase in cellular synthesis machinery, causing cellular growth and proliferation. Here, we describe the development and characterization of novel, potent, and selective eIF4E inhibitors. Compounds from this chemical series have nanomolar activity in multiple biochemical and biophysical m7G cap-competition assays as well as potent inhibition of translation in cellular and biochemical assays. In cells, these compounds rapidly and reversibly decrease protein levels of several oncogenes, including CCND1, leading to a G1 cell cycle arrest. We demonstrate that eIF4E inhibitors cause growth inhibition in a variety of breast cancer cell lines, including ER+ breast cancer. These inhibitors also inhibit growth of breast cancer lines with acquired resistance to Palbociclib with the same potency as the parental cell lines. Additionally, eIF4E inhibition shows an increased sensitivity in resistant cell lines when combined with standard of care (SOC), including Palbociclib. Select analogs from the series demonstrate favorable ADMET/PK properties with good oral bioavailability and low safety risk. Lastly, these compounds have demonstrated near complete tumor growth inhibition in non-breast cancer in vivo models. Ongoing experiments will address in vivo efficacy in ER+ breast cancer in both monotherapy and in combination with SOC. Citation Format: Matthew Friedersdorf, Devon Blake, Sarah Thompson, Krista Marran, Jessica Sorrentino. Pharmacological eIF4E inhibition suppresses anti-tumor activity in ER+ breast cancer [abstract]. In: Proceedings of the 2023 San Antonio Breast Cancer Symposium; 2023 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2024;84(9 Suppl):Abstract nr PO5-27-09.

Abstract PO4-08-01: Methylsterol monooxygenase 1 (MSMO1) modulates endoplasmic reticulum stress through cholesterol metabolic reprogramming to alter chemotherapy sensitivity in breast cancer

Abstract Background Endoplasmic reticulum stress (ER stress) is a process in which cells activate unfolded protein response and other signaling pathways in response to misfolded and unfolded protein aggregation and calcium ion balance disturbance in the endoplasmic reticulum cavity. Depending on the intensity of endoplasmic reticulum stress, it can not only induce chaperone expression to play a protective effect, but also induce apoptosis independently. Metabolic reprogramming is one of the characteristics of tumor, which refers to the metabolic changes that cells make in response to various stimuli. Here, we demonstrate that methylsterol monooxygenase 1 (MSMO1) regulates cellular cholesterol metabolism and influences breast cancer susceptibility to chemotherapy by regulating the relative intracellular T-MAS content. Methods RNA-seq was performed on core needle biopsy samples from 26 patients receiving neoadjuvant chemotherapy for breast cancer to screen for genes that may influence neoadjuvant chemotherapy sensitivity. Cell proliferation, CCK8 assay and apoptosis assay were performed for MSMO1 phenotype study. Transmission electron microscopy (TEM) was conducted to visualize the structure of endoplasmic reticulum. Western Blot was used to detect the activation level of the unfolded protein response pathway. The relative content of sterols in MSMO1 knockdown cells was detected by targeted lipid mass spectrometry. AO/PI staining of breast cancer organoids was performed to verify the effect of MSMO1 metabolic substrate T-MAS on chemotherapy drug sensitivity. Results RNA-seq of core needle biopsy samples from breast cancer patients receiving neoadjuvant chemotherapy suggested that MSMO1 was highly expressed in non-pCR patients, and clinical survival data suggested that MSMO1 was associated with poor prognosis in patients with all types of breast cancer, suggesting that MSMO1 might be related to chemotherapy sensitivity of breast cancer. Phenotypic experiments revealed that MSMO1 regulates chemotherapy sensitivity of breast cancer both in vivo and in vitro. Ectopic overexpression of MSMO1 promoted cancer cell resistance to chemotherapy. To uncover the underlying mechanisms, RNA-seq of MSMO1 knock-down cells were carried out and identified that MSMO1 was associated with ER stress. TEM and western blot assay indicated that downregulation of MSMO1 expression leads to endoplasmic reticulum swelling and activation of the unfolded protein response. Considering that MSMO1 is a cholesterol metabolizing enzyme, targeted lipids mass spectrometry was performed to detect the changes in the contents of various intermediate metabolites in the cholesterol pathway, which indicated that the relative content of T-MAS, a metabolic substrate of MSMO1, was significantly up-regulated in MSMO1 knockdown cells. Then, in order to verify whether this metabolite can independently regulate ER stress, breast cancer cells were given T-MAS externally, and TEM and Western Blot analysis indicated that T-MAS could induce ER stress and activate the unfolded protein response independently. Apoptosis assay and AO/PI staining of breast cancer organoids revealed that T-MAS can improve the sensitivity of breast cancer to chemotherapy drugs. Conclusion In summary, these results shed light on the role of MSMO1 in cholesterol metabolism reprogramming, which adjust the endoplasmic reticulum stress state of cells by changing the relative content of intracellular T-MAS, and thereby influencing the sensitivity of breast cancer chemotherapy. As an intermediate metabolite of cholesterol metabolism, T-MAS has potential clinical application value of chemotherapy sensitization. Citation Format: Hengyu Ren, Liren Wangxu, Yayun Chi, Jiong Wu. Methylsterol monooxygenase 1 (MSMO1) modulates endoplasmic reticulum stress through cholesterol metabolic reprogramming to alter chemotherapy sensitivity in breast cancer [abstract]. In: Proceedings of the 2023 San Antonio Breast Cancer Symposium; 2023 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2024;84(9 Suppl):Abstract nr PO4-08-01.

Polyphyllin I ameliorates gefitinib resistance and inhibits the VEGF/VEGFR2/p38 pathway by targeting HIF-1a in lung adenocarcinoma

BackgroundLung adenocarcinoma (LUAD) is the most common pathological type of lung cancer. Epidermal growth factor receptor tyrosine kinase inhibitors (EGFR-TKIs) have been administered as the first-line therapy for patients with EGFR mutations in LUAD, but it is almost inevitable that resistance to EGFR-TKIs therapy eventually arises. Polyphyllin I (PPI), derived from Paris polyphylla rhizomes, has been shown to have potent anti-cancer properties in a range of human cancer types including LUAD. However, the role of PPI in gefitinib resistance and the underlying mechanism remain elusive. PurposeTo evaluate the antitumor impacts of PPI on gefitinib resistance cells and investigate its molecular mechanism. MethodsCCK-8, wound healing, transwell assay, and xenograft model were performed to determine the anti-cancer effects of PPI as well as its ability to overcome gefitinib resistance. Immunoblotting, co-immunoprecipitation, phospho-RTK antibody array, qRT-PCR, and immunofluorescence were utilized to explore the mechanism by which PPI overrides gefitinib resistance. ResultsPPI inhibited cell survival, growth, and migration/invasion in both gefitinib-sensitive (PC9) and -resistant (PC9/GR) LUAD cells (IC50 at 2.0 μM). Significantly, treatment with PPI at 1.0 μM resensitized the resistant cells to gefitinib. Moreover, cell-derived xenograft experiments revealed that the combination of PPI and gefitinib overcame gefitinib resistance. The phospho-RTK array and immunoblotting analyses showed PPI significant inhibition of the VEGFR/p38 pathway. In addition, molecular docking suggested the interaction between PPI and HIF-1α. Mechanistically, PPI reduced the protein expression of HIF-1α in both normoxia and hypoxia conditions by triggering HIF-1α degradation. Moreover, HIF-1α protein but not mRNA level was elevated in gefitinib-resistant LUAD. We further demonstrated that PPI considerably facilitated the binding of HIF-1α to VHL. ConclusionsWe present a novel discovery demonstrating that PPI effectively counteracts gefitinib resistance in LUAD by modulating the VEGF/VEGFR/p38 pathway. Mechanistic investigations unveil that PPI facilitates the formation of the HIF-1α /VHL complex, leading to the degradation of HIF-1α and subsequent inhibition of angiogenesis. These findings uncover a previously unidentified mechanism governing HIF-1α expression in reaction to PPI, providing a promising method for therapeutic interventions targeting EGFR-TKI resistance in LUAD.

USP3 inhibition is Active Against Chemo-resistant Hepatocellular Carcinoma Anchorage-independent Growth via Suppressing Wnt/β-catenin.

USPs are a family of enzymes that regulate protein degradation, and their dysregulation has been implicated in the development and progression of cancer. This study aimed to determine whether ubiquitin-specific proteases 3 (USP3) could be a potential target for therapy in hepatocellular carcinoma (HCC), particularly in resistant HCC. This study systematically investigated the role of USP3 in HCC, with a focus on chemo-resistant HCC cells. The level of USP3 from clinical samples was measured using an ELISA assay. Cell proliferation, apoptosis, migration, and anchorage-independent colony formation assays were performed. Transfection was performed to knock down USP3 expression and measure β-catenin activity, and real-time PCR was used to measure levels of MYC and CYCLIN D1 genes. USP3 protein was upregulated in HCC tissues, but its upregulation was not associated with clinicopathology. USP3 knockdown had a similar inhibitory effect on growth in both sensitive and resistant HCC cells, did not affect migration, and induced apoptosis in sensitive but not resistant HCC cells. Furthermore, USP3 knockdown was more effective in suppressing anchorage-independent colony formation in chemoresistant HCC cells compared to their chemo-sensitive counterparts. Pearson correlation coefficient analysis revealed a strong positive correlation between USP3 and CTNNB1, and consistently, USP3 knockdown reduced the levels and activities of β-catenin in HCC cells. Using a Wnt activator (lithium) in rescue studies significantly reversed the inhibitory effects of USP3 knockdown. The findings suggest that inhibiting USP3 is an effective strategy against cancer stem cells and chemo-resistant HCC cells.

Three-in-one DNA nanowheels for simultaneous tumor regression and drug resistance prevention in breast cancer model

Herein, we proposed novel three-in-one DNA nanowheels with simultaneous chemo and gene therapy to treat tumor, especially to prevent simultaneous drug resistance, which could be disassembled via a cascaded hybridization reactions triggered by the highly expressed microRNA in cancer cells for smart and efficient cancer therapy. Typically, with breast cancer as a model, microRNA 21 could trigger the self-disassembly of DNA nanowheel 1 via hybridization with a specially designed oligonucleotide (anti-microRNA 21) in DNA nanowheel 1, releasing another special oligonucleotide (Contact sequence) to trigger the self-disassembly of DNA nanowheel 2 with releasing of a special oligonucleotide (anti-Contact sequence) to trigger the self-disassembly of DNA nanowheel 1 cyclically, and thus the cascaded hybridization reactions with three-in-one anti-cancer functions could be generated based on three main therapeutic effects via releasing doxorubicin to inhibit macromolecular biosynthesis, antisense oligonucleotide of microRNA 21 to activate the apoptotic cell pathway and antisense oligonucleotide of MDR1 to prevent the drug resistance respectively. As expected, the proposed method showed improved therapeutic efficacy on the cancer cells with about 80% apoptosis ratio, especially on the drug resistant cancer cells with about 75% apoptosis ratio, compared with that in the conventional anti-cancer systems of about 70% on cancer cells and below 40% on drug resistant cancer cells, respectively. Most importantly, this strategy opened the door for generation of complex functional DNA-based structures for target triggering drugs releasing system combining with chemo- and gene-therapy to generate tumor regression and prevent drug resistance with an optimized therapeutic efficacy, providing a new avenue for efficient cancer treatment, especially drug resistant cancers.

MCM5 is a Novel Therapeutic Target for Glioblastoma.

MCM5 is a DNA licensing factor involved in cell proliferation and has been previously established as an excellent biomarker in a number of malignancies. Nevertheless, the role of MCM5 in GBM has not been fully clarified. The present study aimed to investigate the potential roles of MCM5 in the treatment of GBM and to elucidate its underlying mechanism, which is beneficial for developing new therapeutic strategies and predicting prognosis. Firstly, we obtained transcriptomic and proteomic data from the TCGA and CPTAC databases on glioma patients. Employing the DeSeq2 R package, we then identified genes with joint differential expression in GBM tissues subjected to chemotherapy. To develop a prognostic risk score model, we performed univariate and multivariate Cox regression analyses. In vitro knockdown and overexpression of MCM5 were used to further investigate the biological functions of GBM cells. Additionally, we also delved into the upstream regulation of MCM5, revealing associations with several transcription factors. Finally, we investigated differences in immune cell infiltration and drug sensitivity across diverse risk groups identified in the prognostic risk model. In this study, the chemotherapy-treated GBM samples exhibited consistent alterations in 46 upregulated and 94 downregulated genes at both the mRNA and protein levels. Notably, MCM5 emerged as a gene with prognostic significance as well as potential therapeutic relevance. In vitro experiments subsequently validated the role of increased MCM5 expression in promoting GBM cell proliferation and resistance to TMZ. Correlations with transcription factors such as CREB1, CTCF, NFYB, NRF1, PBX1, TEAD1, and USF1 were discovered during upstream regulatory analysis, enriching our understanding of MCM5 regulatory mechanisms. The study additionally delves into immune cell infiltration and drug sensitivity, providing valuable insights for personalized treatment approaches. This study identifies MCM5 as a key player in GBM, demonstrating its prognostic significance and potential therapeutic relevance by elucidating its role in promoting cell proliferation and resistance to chemotherapy.

Acquisition of Doxorubicin Resistance Induces Breast Cancer Cell Migration and Epithelial-Mesenchymal Transition that are Reversed by Shikonin-Metformin Synergy

Background: Drug resistance is a major challenge in cancer chemotherapy. Methods: By adopting an appropriately timed strategy, we generated MCF-7 cell sublines resistant to serial doses of doxorubicin (DOX). Our higher-dose sublines showed more stability in resistance and were, therefore, subjected to further analyses. We tested the consistency of drug resistance by comparing sublines with control groups for growth and migration capacities. Molecular analyses monitored expression changes, CD44/CD24 ratios, and DOX binding to key molecules. The reverting impact of shikonin (SHKN) and metformin (MTFN) on DOX resistance was examined. Results. The resistant sublines grew parallel to or even faster than WT MCF-7 cells and showed a larger and more rounded morphology. The consistency of their drug resistance and invasive potential was demonstrated over time using serial doses of DOX. Real-time PCR revealed upregulation of genes involved in cell growth and survival, drug resistance, migration/invasion, and epithelial-mesenchymal transition and, conversely, downregulation of pro-apoptotic, anti-chemoresistance, and tumor suppressor genes. SHKN-MTFN co-treated resistant cells showed significantly lower CD44/CD24 ratios, less aggressiveness, and reduced survival and migration rates but enhanced apoptosis. SHKN’s affinity to CYP1A and TOP2A demonstrated the importance of these interactions and the compounds’ capacity to compete with DOX. Conclusion: Acquisition of DOX resistance increases tumorigenic properties of cancer cells, whereas synergy between selective anti-tumorigenic compounds re-sensitizes resistant cells by reverting cellular pathways that favor or follow resistance. Our findings suggest that this reversal is supported by competing reactions that deprive DOX of binding to its target molecules.

Iron-Based Thermally Regenerative Flow Battery Recharged by Distillation of Acetone

Thermo-electrochemical conversion systems can convert abundant low-grade heat into electricity. In particular, thermally regenerative flow batteries (TRFBs) have gained significant attention owing to their high power density compared to other thermo-electrochemical conversion systems. However, the variety of redox species is limited in previous studies. To provide an alternative option for the redox species, we newly propose using Fe, and investigate the performance of an Fe-based TRFB called the solvation difference flow battery (SDFB). In this study, the SDFB uses [Fe(CN)6]4−/3− as the redox species and can be recharged by the distillation of acetone. The maximum power density was 40 W m−2 and the thermal efficiency was estimated to be 0.20% at an average power density of 16 W m−2. In addition, we discuss the challenges for future improvements. The cell voltage should be enhanced by optimizing the electrolyte components, such as solvents and counterions. For the cell design, the cell resistance is reduced by improving the flow fields of the electrolytes to enhance the mass-transfer properties. Moreover, a membrane that satisfies both a high ion conductivity and low crossover rate of the solvents is required. This study provides new options for the redox species in TRFBs.

Phlorizin from Lithocarpus litseifolius [Hance] Chun ameliorates FFA-induced insulin resistance by regulating AMPK/PI3K/AKT signaling pathway

BackgroundInsulin resistance (IR) is the central pathophysiological feature in the pathogenesis of metabolic syndrome, obesity, type 2 diabetes mellitus (T2DM), hypertension, and dyslipidemia. As the main active ingredient in Lithocarpus litseifolius [Hance] Chun, previous studies have shown that phlorizin (PHZ) can reduce insulin resistance in the liver. However, the effect of phlorizin on attenuating hepatic insulin resistance has not been fully investigated, and whether this effect is related to AMPK remains unclear. PurposeThe present study aimed to further investigate the effect of phlorizin on attenuating insulin resistance and the potential action mechanism. MethodsFree fatty acids (FFA) were used to induce insulin resistance in HepG2 cells. The effects of phlorizin and FFA on cell viability were detected by MTT analysis. Glucose consumption, glycogen synthesis, intracellular malondialdehyde (MDA), superoxide dismutase (SOD), total cholesterol (TC), and triglyceride (TG) contents were quantified after phlorizin treatment. Glucose uptake and reactive oxygen species (ROS) levels in HepG2 cells were assayed by flow cytometry. Potential targets and signaling pathways for attenuating insulin resistance by phlorizin were predicted by network pharmacological analysis. Moreover, the expression levels of proteins related to the AMPK/PI3K/AKT signaling pathway were detected by western blot. ResultsInsulin resistance was successfully induced in HepG2 cells by co-treatment of 1 mM sodium oleate (OA) and 0.5 mM sodium palmitate (PA) for 24 h. Treatment with phlorizin promoted glucose consumption, glucose uptake, and glycogen synthesis and inhibited gluconeogenesis in IR-HepG2 cells. In addition, phlorizin inhibited oxidative stress and lipid accumulation in IR-HepG2 cells. Network pharmacological analysis showed that AKT1 was the active target of phlorizin, and the PI3K/AKT signaling pathway may be the potential action mechanism of phlorizin. Furthermore, western blot results showed that phlorizin ameliorated FFA-induced insulin resistance by activating the AMPK/PI3K/AKT signaling pathway. ConclusionPhlorizin inhibited oxidative stress and lipid accumulation in IR-HepG2 cells and ameliorated hepatic insulin resistance by activating the AMPK/PI3K/AKT signaling pathway. Our study proved that phlorizin played a role in alleviating hepatic insulin resistance by activating AMPK, which provided experimental evidence for the use of phlorizin as a potential drug to improve insulin resistance.

Gelsolin knockdown confers radiosensitivity to glioblastoma cells.

Radiotherapy (RT) is a cornerstone of the glioblastoma (GBM) treatment. However, the resistance of tumour cells to radiation results in early recurrence. The mechanisms underlying GBM radioresistance remain unclear. Screening for differentially expressed genes (DEGs) related to radiation might be a potential solution to this problem. RT-associated DEGs were screened based on the RNA sequencing of 15 paired primary and recurrent GBMs. The mRNA and protein expression of candidate genes were validated in RNA sequencing of The Chinese Genome Atlas (CGGA) dataset and 18 cases of GBM samples. The relationship between the candidate gene and radiation was confirmed in irradiated GBM cells. The association of candidate gene with clinical characteristics and survival was investigated in the CGGA and TCGA dataset. Biological function and pathway analysis were explored by gene ontology analysis. The association of the candidate gene with radiosensitivity was verified using cell counting Kit-8, comet, and colony formation assays invitro and subcutaneous tumour xenograft experiments invivo. Gelsolin (GSN) was selected for further study. GSN expression was significant elevated in recurrent GBM and up-regulated in irradiated GBM cell lines. High expression of GSN was enriched in malignant phenotype of glioma. Moreover, high expression of GSN was associated with poor prognosis. Further investigation demonstrated that GSN-knockdown (GSN-KD) combined with RT significantly inhibited cell proliferation and enhanced radiosensitivity invivo and invitro. Mechanistically, GSN-KD could lead to more serious DNA damage and promotes apoptosis after RT. Radiation induced up-regulated of GSN. GSN-KD could enhance the radiosensitivity of GBM.

A Novel Mechanism Underlying Apoptosis Resistance in Pulmonary Arterial Smooth Cuscle Cells (PASMCs)

RATIONALE: Pulmonary hypertension (PH) is characterized by pulmonary vascular remodeling, with PASMC hyperplasia and formation of vaso-occlusive lesions. New data show PASMCs isolated from robust animal models of PH are resistant to apoptosis, a feature which may propagate disease as abnormal PASMCs evade death. Apoptosis is a highly regulated pathway resulting in caspase-3 (casp3) activation and translocation to the nucleus, where cleavage of proteins results in cell death. In several cancers the membrane protein aquaporin 1 (AQP1) plays a role in apoptosis resistance, although the mechanism remains unknown. We showed AQP1 is expressed in PASMCs and increased in rat models of PH. Therefore, we hypothesized increased AQP1 contributes to apoptosis resistance in PASMCs. METHODS: The Sugen-hypoxia (SuHx) rat model of PH was used. Rats were injected with vascular endothelial growth factor receptor type 2 inhibitor Sugen-5416 and placed in 10% O2 for 3 wk, then returned to 21% O2 for 2 wk. Control animals received vehicle injection and were kept in 21% O2. Distal PASMCs were isolated via enzymatic digestion. AQP1 was depleted in SuHx PASMCs with small interfering RNA (siAQP1), with non-targeting siRNA as control. AQP1 was overexpressed in control PASMCs with adenoviral constructs containing wild type AQP1 (AdAQP1) or green fluorescent protein (control). Cells were treated with PBS or pro-apoptotic hydrogen peroxide (500 μM; 24 h). Apoptosis was measured by Hoechst staining. Caspase activity was measured via luminescent caspase-3/7 activity assay (Caspase-Glo® 3/7) in whole cell lysates and nuclear fractions. RESULTS: Depleting AQP1 via siAQP1 restored apoptosis susceptibility in SuHx PASMCs, and overexpressing AQP1 via AdAQP1 reduced susceptibility to apoptosis in control PASMCs. At baseline, there was no difference in casp3 activity between SuHx and control total cell lysates. However, casp3 activity was lower in SuHx nuclear fractions. Under stimulated conditions, SuHx PASMCs exhibited significantly less total and nuclear casp3 activity, with nuclear activity similar to levels observed in unstimulated controls. To explore an underlying mechanism for these findings, in silico analysis of AQP1 was performed revealing 3 potential casp3 cleavage sites, suggesting the possibility these proteins could interact. To investigate a potential protein-protein interaction, proximity-based biotinylation assays were performed in PASMCs using AdAQP1 (control) or AQP1 fused to biotin ligase. Cells were incubated with cell-permeable biotin (50 μM), lysed, and biotinylated proteins precipitated and immunoblotted for casp3 and other cytosolic proteins not expected to interact with AQP1. To confirm bidirectionality, similar biotinylation assays were performed using adenoviral constructs with wild-type (control) or biotin ligase-fused casp3 and immunoblotting for AQP1. Results showed a specific AQP1/casp3 interaction in PASMCs. Furthermore, the predominant form of casp3 interacting with AQP1 appears to be inactive (37kD). CONCLUSION: We speculate that increased AQP1 in SuHx PASMCs interacts with casp3 preventing its activation and/or nuclear translocation, conferring apoptosis resistance. Future studies further characterizing the interaction between AQP1 and casp3 could provide the basis for novel therapeutic targets focused on restoring PASMC apoptosis susceptibility. F32 HL165766-01, T32 HL007534, Bauernschmidt Fellowship. This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Targeting BIRC5 as a therapeutic approach to overcome ASXL1-associated decitabine resistance

Hypomethylating agents (HMAs) are widely employed in the treatment of myeloid malignancies. However, unresponsive or resistant to HMAs occurs in approximately 50 % of patients. ASXL1, one of the most commonly mutated genes across the full spectrum of myeloid malignancies, has been reported to predict a lower overall response rate to HMAs, suggesting an essential need to develop effective therapeutic strategies for the patients with HMA failure. Here, we investigated the impact of ASXL1 on cellular responsiveness to decitabine treatment. ASXL1 deficiency increased resistance to decitabine treatment in AML cell lines and mouse bone marrow cells. Transcriptome sequencing revealed significant alterations in genes regulating cell cycle, apoptosis, and histone modification in ASXL1 deficient cells that resistant to decitabine. BIRC5 was identified as a potential target for overcoming decitabine resistance in ASXL1 deficient cells. Furthermore, our experimental evidence demonstrated that the small-molecule inhibitor of BIRC5 (YM-155) synergistically sensitized ASXL1 deficient cells to decitabine treatment. This study sheds light on the molecular mechanisms underlying the ASXL1-associated HMA resistance and proposes a promising therapeutic strategy for improving treatment outcomes in affected individuals.

Optimizing the metallization process for high fill factor of n-type crystalline silicon TOPCon solar cells

The primary challenge in solar cell manufacture concerning the metallization process is the need to achieve a balance between the electrical and optical performance of the metal contacts as the contribute to shading and the series resistance (Rs) of solar cells. Addressing these challenges with the optimization of the metallization process is crucial for achieving a high fill factor (FF) in solar cells, as FF is a key parameter indicating the quality and efficiency of a solar cell. An impact of different snap-off, distances between mask and cells, of n-type TOPCon (Tunnel Oxide Passivated Contact) solar cells during the screen-printing process was conducted. This experiment employs testing and analysis to determine the most effective snap-off distance that minimizes the Rs variability, resulting in an overall enhancement in cell efficiency. The smaller snap-off distance can lead to better performance in n-TOPCon solar cells due to finer lines, uniform contacts, and lower Rs. The I-V characteristics of 1.4 mm are Jsc of 39.58 mA/cm2, Voc of 684.63 mV, FF of 80.54 %, and power conversion efficiency (PCE) of 21.83 %, respectively. In addition, dark I-V measurement is essential for diagnosing performance issues; we got shunt resistance (Rsh) of 4.97 x 106 Ω which is the highest value that indicates minimal Rs of 0.3 Ω. As a result, it is a potential strategy for n-TOPCon solar cell improvements.