Mechanisms Of Chemotherapy Resistance Research Articles

The Contribution of the Novel CLTC-VMP1 Fusion Gene to Autophagy Regulation and Energy Metabolism in Cisplatin-Resistant Osteosarcoma.

Osteosarcoma (OS) is a highly malignant tumor, and chemotherapy resistance is a major challenge in the treatment of this disease. This study aims to explore the role of the CLTC-VMP1 gene fusion in the mechanism of chemotherapy resistance in OS and investigate its molecular mechanisms in mediating energy metabolism reprogramming by regulating autophagy and apoptosis balance. Using single-cell transcriptome analysis, the heterogeneity of OS cells and their correlation with resistance to platinum drugs were revealed. Cisplatin-resistant cell lines were established in human OS cell lines for subsequent experiments. Based on transcriptomic analysis, the importance of VMP1 in chemotherapy resistance was confirmed. Lentiviral vectors overexpressing or interfering with VMP1 were used, and it was observed that inhibiting VMP1 could reverse cisplatin resistance, promote cell apoptosis, and inhibit autophagy, as well as mitochondrial respiration and glycolysis. Furthermore, the presence of CLTC-VMP1 gene fusion was validated, and its ability to regulate autophagy and apoptosis balance, promote mitochondrial respiration, and glycolysis was demonstrated. Mouse model experiments further confirmed the promoting effect of CLTC-VMP1 on tumor growth and chemotherapy resistance. In summary, the CLTC-VMP1 gene fusion mediates energy metabolism reprogramming by regulating autophagy and apoptosis balance, which promotes chemotherapy resistance in OS.

MiRNAs: Potential as Biomarkers and Therapeutic Targets for Cancer

Background MicroRNAs (miRNAs) are pivotal regulators of gene ex-pression, playing a significant role in various human and canine disorders.Dysregulation of miRNA expression is a hallmark of most malignancies.Objective This review aims to analyze the importance of miRNAs in cancer research, focusing on their potential as diagnostic and prognostic biomarkers. Additionally, the study explores the therapeutic possibilities of miRNA-based therapies and the role of miRNAs in revealing mechanisms of resistance to conventional chemotherapy.Results The study underscores the diverse roles of miRNAs in cancer research. miRNAs hold promise as diagnostic and prognostic indicators,offering significant clinical insights. Furthermore, miRNA-based therapies show potential in. improving patient outcomes by providing tailored ap- proaches to cancer treatment. Understanding miRNA production and reg-ulation in cancer can elucidate mechanisms of chemotherapy resistance, paving the way for more effective cancer therapies.Conclusion miRNAs hold immense promise for revolutionizing cancer management through liquid biopsies. Their ability to facilitate early detec-tion, monitor disease progression, and guide personalized therapies offers a powerful tool in the fight against cancer. As research progresses, we can anticipate a future where liquid biopsies powered by miRNAs become a cornerstone of effective cancer care, leading to improved patient outcomes and a brighter future for cancer management.

Injectable Hydrogel-Encapsulating Pickering Emulsion for Overcoming Lenvatinib-Resistant Hepatocellular Carcinoma via Cuproptosis Induction and Stemness Inhibition.

Lenvatinib resistance (LenR) presents a significant challenge in hepatocellular carcinoma (HCC) treatment, leading to high cancer-related mortality rates globally. Unlike traditional chemotherapy resistance mechanisms, LenR in HCC is primarily driven by increased cancer cell stemness. Disulfiram, (DSF), functioning as a Cu ionophore, can coordinate with Cu2+ to overcome LenR in HCC by inhibiting cancer cell stemness and cuproptosis. However, DSF faces challenges due to its poor water solubility, while copper ions present issues related to systemic toxicity during widespread use. To address this, DSF and CuO nanoparticles (NPs) were co-encapsulated to form an oil-in-water Pickering emulsion (DSF@CuO), effectively elevating DSF and copper ion concentrations within the tumor microenvironment (TME). DSF@CuO was then combined with sodium alginate (SA) to form a DSF@CuO-SA solution, which gelatinizes in situ with Ca2+ in the TME to form a DSF@CuO Gel, enhancing Pickering emulsion stability and sustaining DSF and copper ion release. A DSF@CuO Gel exhibits enhanced stability and therapeutic efficacy compared to conventional administration methods. It effectively induces mitochondrial dysfunction and cuproptosis in LenR HCC cells by downregulating DLAT, LIAS, and CDKN2A, while upregulating FDX1. Furthermore, it suppresses cancer stemness pathways through activation of the JNK/p38 MAPK pathway and inhibition of the NF-κB and NOTCH signaling pathways. These findings suggest that DSF@CuO Gels are a promising therapeutic strategy for treating LenR HCC. In vivo and in vitro LenR HCC models demonstrated significant therapeutic efficacy. In conclusion, this novel approach underscores DSF@CuO Gel's potential to overcome LenR in HCC, offering a novel approach to address this clinical challenge.

Multi‐omics molecular phenotyping reveals the potential mechanisms of chemotherapy response and resistance in small cell lung cancer

Multi‐omics molecular phenotyping reveals the potential mechanisms of chemotherapy response and resistance in small cell lung cancer

Cancer associated fibroblast secreted miR-432-5p targets CHAC1 to inhibit ferroptosis and promote acquired chemoresistance in prostate cancer.

Prostate cancer (PCa) ranks as the sixth most serious male malignant disease globally. While docetaxel (DTX) chemotherapy is the standard treatment for advanced PCa patients with distant metastasis, some individuals exhibit insensitivity or resistance to DTX. Cancer-associated fibroblasts (CAFs) play a pivotal role as stromal cells within the tumor microenvironment, influencing tumor development, progression, and drug resistance through exosomes. Ferroptosis, a novel form of programmed cell death, is characterized by intracellular iron accumulation that triggers lipid peroxidation, ultimately leading to cell demise. To delve into the potential mechanisms of chemotherapy resistance in prostate cancer, our research delved into the impact of CAF-derived exosomes on ferroptosis. Our findings revealed that CAF exosomes hindered the buildup of lipid reactive oxygen species (ROS) in prostate cancer cells induced by erastin, as well as mitigated erastin-induced mitochondrial damage, thereby impeding iron-induced cell death in prostate cancer cells. Furthermore, miR-432-5p was identified to diminish glutathione (GSH) consumption by targeting CHAC1, consequently inhibiting ferroptosis in prostate cancer cells. Our study found that miR-432-5p, originating from cancer-associated fibroblast (CAF) exosomes, suppresses ferroptosis by targeting CHAC1, thereby increasing resistance to docetaxel (DTX) in PCa. This research introduces a novel approach to address resistance to DTX.

Impact of Doxorubicin and Docetaxel on Immune Checkpoint Expression in Colorectal Cancer: Insights into Chemotherapy Resistance Mechanisms

Impact of Doxorubicin and Docetaxel on Immune Checkpoint Expression in Colorectal Cancer: Insights into Chemotherapy Resistance Mechanisms

Abstract 306: The role of exosomal UBE2R2 in colorectal cancer drug resistance

Abstract Background: Ctherapy resistance has been a major barrier against successful theratment. Exosome (EV), an important intercellular communication mediator, participates in a highly and complex network that drug resistance of cancer cells. EV has been reported to be able to transfer drug resistance from drug-resistant tumor cells to adjacent drug-sensitive cells. We identified a novel target, UBE2R2, based on our previous exosome proteomics analysis of resistant colorectal cancer cell lines. The main goal of this study is to validate the underlying mechanisms leading to chemotherapy resistance. Methods: We isolated EV from drug resistant cancer cell lines including coloractal cancer cell lines (HCT116-OXAR, DLD-1 OXA-R, DLD-1-OXA-R/SN38) its parental cell lines (HCT116, DLD-1) using the ExoLutE isolation kits based on a combination of multiple isolation techniques. Based on the existing data (proteomic analysis), we conducted experiments to elucidate the functions and mechanisms involved in cancer resistance of the identified UBE2R2. Cell viability assay and invasion asaay were performed to assess the effects of EVs drived from drug resistance colorectal cells on oxaliplatin and irinotecan resistance. In addition, cells transfected with siControl and siUBE2R2 were treated with oxaliplatin to access the relative UBE2R2 drug resistance effect. To explore the related mechanisms, we performed real time PCR and western blot to identify the UBE2R2-SMYD3-P53 pathway, and FACS analysis to confirm apoptosis. Additionally, TMA samples were utilized to confirm resistance according to patient stage, and UBE2R2 expression was validated by immunohistological methods. Results: UBE2R2, which is involved in ubiquitination, was most prominently expressed in resistant cell lines compared to controls in our previous proteomic analysis. Based on these results, we found that cell lines treated with exosomes which were derived from resistant cell lines showed lower sensitivity to the drug. Notably, treatment of resistant cell lines with siUBE2R2 resulted in increased sensitivity, confirming the involvement of UBE2R2 in resistance. As a possible mechanism in which UBE2R2 may be involved, western analysis targeting the SMYD-P53 mechanism showed that the combination of UBE2R2-SMYD3-p53 promoted the ubiquitination and degradation of p53. Analyzed using TMA patient samples, we found that the expression of UBE2R2 increased towards more advenced stage. Conclusion: Our results suggest a novel mechanism of chemotherapy resistance may be associated with UBE2R2. Exosome (including UBE2R2) which was drived from drug resistance cells may induce oxaliplatin and irinotecan resistance in parental colorectal cells via regulation of SMYD3-UBE2R2-P53 signaling pathway, which will be useful for investigating a potential clinical target in prediction drug resistance. Citation Format: Chi Hoon Maeng, Minji Choi. The role of exosomal UBE2R2 in colorectal cancer drug resistance [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 306.

Abstract 2019: Primary cancer associated fibroblasts increase the chemoresistance of triple negative breast cancer cells by mitochondria metabolic upregulation

Abstract Breast cancers (BCs) are the most prevalent cancers occurring in women. Tumor reoccurrence attributed to chemotherapy resistance remains a main challenge in fighting disease relapse. Cancer associated fibroblasts (CAFs) are the most prominent component of the tumor microenvironment (TME) and have already been implicated in therapy resistances. Although the exact molecular mechanisms behind this resistance remain unclear. In this regard, we recently identified 4 CAF populations (S1-S4) in ovarian and BCs, and showed that only CAF-S1 promote immunotherapy resistance as well as metastasis. Based on these observations, we are now investigating the impact of CAF-S1 on the chemotherapy response of BCs. To study the interactions between CAF-S1 and BC cells, we developed a tumor on chip (ToC) device, mimicking the TME in 3D. Using ToC live imaging, we show that primary CAF-S1 mediate a chemoprotective effect over luminal and triple negative BC (TNBC) cells by significantly decreasing their apoptosis rate as early as 10h after Doxorubicin and 40h after Paclitaxel treatment. Interestingly, CAF-S1 display a highly heterogenous response to Doxorubicin, allowing the classification into chemo-sensitive and -resistant CAF-S1. Regardless of premature CAF-S1 cell death, the chemoprotective effect over BC cells is maintained for at least 3 days. This indicates a crucial CAF-S1 - cancer cell cross talk at early timepoints. Additionally, by applying machine learning algorithms on live imaging videos, we demonstrate that physical proximity of CAF-S1 to BC cells immediately after treatment initiation correlates with BC cell survival, even after several days of treatment. This again implies cancer cell priming by CAF-S1 as a possible mechanism of chemotherapy resistance. To investigate this molecular interplay further, we performed scRNA-seq of ToC extracted and treatment naïve CAF-S1 and TNBC cells as well as bulk RNA-seq of patient derived TNBC tumors before/after chemotherapy treatment. We identify mitochondrial metabolic pathways to be upregulated in TNBC cells after CAF-S1 co-culture inside ToC devices and in TNBC cells of chemo-resistant patients enriched in CAF-S1 at baseline. We are now validating the impact of target gene knock downs on the survival of TNBC cells in CAF-S1 co-cultures after chemotherapy treatment on chip. Overall, these results provide insights into molecular mechanisms by which CAF-S1 promote chemotherapy resistance of breast cancers. Citation Format: Isabella Hofer, Arianna Mencattini, Yann Kieffer, Eugenio Martinelli, Maria Carla Parrini, Fatima Mechta-Grigoriou. Primary cancer associated fibroblasts increase the chemoresistance of triple negative breast cancer cells by mitochondria metabolic upregulation [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 2019.

Abstract 5852: Tumor gene expression patterns affecting response to BCl-2 inhibitor venetoclax in acute myeloid leukemia

Abstract Background: Venetoclax (VEN), a B-cell lymphoma-2 (BCL-2) inhibitor, is an important drug in acute myeloid leukemia (AML) treatment regimens. However, resistance to VEN-based therapy is a common challenge in AML management. Some factors contributing to resistance include dysregulation of BCL-2 family proteins, mutations in the TP53 gene, activating kinase mutations, and oxidative phosphorylation activity. Despite these insights, other mechanisms of resistance remain elusive. We aim to analyze tumor gene expression patterns associated with treatment response in patients who received VEN-based therapy. Methods: Molecular and clinical data of the patients were obtained as part of the Oncology Research Information Exchange Network (ORIEN) Avatar dataset. RNA-Seq data from diagnostic Bone Marrow were processed to remove batch effects, and differential expression analysis was performed using DESeq2, while correcting for age at sample collection and sex of patients. Results: We included 16 individuals treated with VEN-based therapy. Median age at the time of specimen collection was 65 years (interquartile range, 58-69), 9 (56%) male, 11 (69%) had active disease despite treatment with VEN. VEN-based therapy was used as 1st line, 2nd line, 3rd line, 4th line or more in 3, 4, 4, 2, and 3 patients, respectively. We found a total of 332 genes differentially expressed (fdr<0.05 and abs(log2FoldChange)>2.0) among patients having no evidence of active disease and those with no active disease at the time of last contact. Among those genes, we found HOXA7 and PRAME of particular interest. HOXA7 has been previously implicated in Bromodomain and Extraterminal Domain Inhibitors (BETi) inhibitor resistance in AML. This makes HOXA7 a potentially universal mechanism of chemotherapy resistance in AML. PRAME has been associated with leukemia cell survival, and its knockdown has been shown to induce apoptosis in K562 cells, which is only expressed in AML cells but not in normal hematopoietic cells. Pathway analysis found that the top two enriched pathways for the differentially expressed genes were MET activates PTK2 signaling (R-HSA-8874081) and Metabolism of Angiotensinogen to Angiotensins(R-HSA-2022377). Conclusions: This study highlights some molecular mechanisms that give rise to AML resistance to VEN. Our results indicate that HOXA7 may potentially be a universal mechanism of chemotherapy resistance not limited to VEN-based therapy. Similarly, pathways enriched in resistant cells could be targeted to prevent or treat resistance to VEN-based therapy. These and other findings may help us identify resistance mechanisms in all AML cases vs those specific to VEN-based therapy, allowing the development of treatment strategies based on treatment mechanism. Also, analysis of these mechanisms can aid therapeutic decision-making and the development of effective treatment strategies to improve outcomes in AML. Citation Format: Juan Antonio Raygoza Garay, Seongseok Yun, Afaf Osman, Reshma Ramlal, David Feith, Michelle Churchman, Prajwal Dhakal. Tumor gene expression patterns affecting response to BCl-2 inhibitor venetoclax in acute myeloid leukemia [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 5852.

Potential tools for predicting response to chemotherapy in OC: Assessment of immune dysbiosis, participant’s self-rated health and microbial dynamics

Epithelial ovarian cancer (OC) is the deadliest female reproductive cancer; an estimated 13,270 women will die from OC in 2023. Platinum-based chemotherapy resistance mechanisms contribute to poor OC 5-year survival rates. Peripheral inflammation is linked to various disease states and we previously identified unique peritoneal microbial features predictive of OC. We hypothesized that unique peripheral immune profiles and peritoneal microbial features may be predictive of disease-free interval (time to recurrence) and response to chemotherapy in participants with OC. We also investigated self-rated health (SRH) scores in the context of peripheral inflammation as a potential screening tool for OC. Blood and peritoneal fluid were collected from participants with OC or a benign adnexal mass (BPM). Lymphocyte populations were analyzed using Fluorescence Activated Cell Sorting, serum cytokine levels were analyzed using the Human Th17 Magnetic Bead Panel assay and peritoneal fluid microbial features were analyzed using Next Generation Sequencing (NGS). Participants completed a standardized questionnaire on self-rated physical and emotional health. Participants were classified into three chemotherapy response categories: platinum-refractory, platinum-resistant or platinum-sensitive. A significant positive correlation was found between elevated inflammatory status on the day of surgery and longer disease-free interval. SRH measures did not correlate with immune status in participants with OC or a BPM. We identified a correlation between peritoneal microbial features and chemotherapy response. We conclude that immune dysbiosis may be useful in predicting OC recurrence. The immune findings reported here set the framework for additional studies utilizing immune profiles to predict platinum-based chemotherapy responsiveness in OC.

Upregulation of PD-L1, VISTA, and CTLA-4 Gene Expression in a Melanoma Cell Line Following Chemotherapy: An In Vitro Study

Background: Melanoma, an aggressive form of skin cancer, has garnered substantial research attention due to its rising incidence and limited treatment efficacy. Tumor cells often become more aggressive post-chemotherapy, evading innate and adaptive immune responses, leading to recurrence and metastasis. Identifying mechanisms of chemotherapy resistance is crucial to reduce mortality rates. Negative immune pathways such as cytotoxic T-lymphocyte-associated protein 4 (CTLA-4), programmed death-ligand 1 (PD-L1), and V-domain Ig suppressor of T cell activation (VISTA) hinder immune responses to cancer. This study aimed to uncover the dynamic alterations in the expression patterns of key immune checkpoints VISTA, PD-L1, and CTLA-4 in melanoma cancer cell line. Methods: In this study, the A-375 melanoma cancer cell line was cultivated using conventional cell culture techniques. The IC50 (half-maximal inhibitory concentration) and efficacy assessment of chemotherapy drugs, docetaxel and doxorubicin, were determined using the MTT test. After treatment, an analysis of the expression of PD-L1, CTLA-4, and VISTA genes in the A-375 cell line was performed using quantitative reverse transcription-polymerase chain reaction (qRT-PCR). One-way analysis of variance (ANOVA) was used for statistical analysis. All experiments were conducted in triplicate, with significance set at P<0.05. Statistical significance is denoted as follows: *P<0.05, **P<0.01, ***P<0.001, and ****P<0.0001. Results: Significant upregulation of VISTA expression was observed in both ADO and ADC groups. CTLA-4 expression increased significantly in the ADC group, while no significant change was observed in the ADO group. PD-L1 expression was significantly higher in both ADO and ADC groups compared to the control group. Conclusion: These compelling findings underscore the profound impact of chemotherapeutic agents on the heightened expression of immune checkpoint genes, shedding light on the potential modulation of crucial pathways associated with immune response regulation.

Insights into molecular mechanisms of chemotherapy resistance in cancer

Cancer heterogeneity poses a significant hurdle to the successful treatment of the disease, and is being influenced by genetic inheritance, cellular and tissue biology, disease development, and response to therapy. While chemotherapeutic drugs have demonstrated effectiveness, their efficacy is impeded by challenges such as presence of resilient cancer stem cells, absence of specific biomarkers, and development of drug resistance. Often chemotherapy leads to a myriad of epigenetic, transcriptional and post-transcriptional alterations in gene expression as well as changes in protein expression, thereby leading to massive metabolic reprogramming. This review seeks to provide a detailed account of various transcriptional regulations, proteomic changes, and metabolic reprogramming in various cancer models in response to three primary chemotherapeutic interventions, docetaxel, carboplatin, and doxorubicin. Discussing the molecular targets of some of these regulatory events and highlighting their contribution in sensitivity to chemotherapy will provide insights into drug resistance mechanisms and uncover novel perspectives in cancer treatment.

Understanding the mechanisms of antimicrobial resistance and potential therapeutic approaches against the Gram-negative pathogen Acinetobacter baumannii.

Globally, the emergence of anti-microbial resistance in pathogens has become a serious threat to human health and well-being. Infections caused by drug-resistant microorganisms in hospitals are associated with increased morbidity, mortality, and healthcare costs. Acinetobacter baumannii is a Gram-negative bacterium belonging to the ESKAPE group and is widely associated with nosocomial infections. It persists in hospitals and survives antibiotic treatment, prompting acute infections such as urinary tract infections, pneumonia, bacteremia, meningitis, and wound-related infections. An innovation void in drug discovery and the lack of new therapeutic measures against A. baumannii continue to afflict infection control against the rising drug-resistant cases. The emergence of drug-resistant A. baumannii strains has also led to the incessant collapse of newly discovered antibiotics. Therefore exploring novel strategies is requisite to give impetus to A. baumannii drug discovery. The present review discusses the bacterial research community's efforts in the field of A. baumannii, focusing on the strategies adapted to identify potent scaffolds and novel targets to bolster and diversify the chemical space available for drug discovery. Firstly, we have discussed existing chemotherapy and various anti-microbial resistance mechanisms in A. baumannii bacterial strains. Next, we elaborate on multidisciplinary approaches and strategies that may be the way forward to combat the current menace caused by the drug-resistant A. baumannii strains. The review highlights the recent advances in drug discovery, including combinational therapy, high-throughput screening, drug repurposing, nanotechnology, and anti-microbial peptides, which are imperative tools to fight bacterial pathogens in the future.

Transient receptor potential channels as predictive marker and potential indicator of chemoresistance in colon cancer.

Transient receptor potential (TRP) channels are strongly associated with colon cancer development and progression. This study leveraged a multivariate Cox regression model on publicly available datasets to construct a TRP channels-associated gene signature, with further validation of signature in real world samples from our hospital treated patient samples. Kaplan-Meier (K-M) survival analysis and receiver operating characteristic (ROC) curves were employed to evaluate this gene signature's predictive accuracy and robustness in both training and testing cohorts, respectively. Additionally, the study utilized the CIBERSORT algorithm and single-sample gene set enrichment analysis to explore the signature's immune infiltration landscape and underlying functional implications. The support vector machine algorithm was applied to evaluate the signature's potential in predicting chemotherapy outcomes. The findings unveiled a novel three TRP channels-related gene signature (MCOLN1, TRPM5, and TRPV4) in colon adenocarcinoma (COAD). The ROC and K-M survival curves in the training dataset (AUC = 0.761; p = 1.58e-05) and testing dataset (AUC = 0.699; p = 0.004) showed the signature's robust predictive capability for the overall survival of COAD patients. Analysis of the immune infiltration landscape associated with the signature revealed higher immune infiltration, especially an increased presence of M2 macrophages, in high-risk group patients compared to their low-risk counterparts. High-risk score patients also exhibited potential responsiveness to immune checkpoint inhibitor therapy, evident through increased CD86 and PD-1 expression profiles. Moreover, the TRPM5 gene within the signature was highly expressed in the chemoresistance group (p = 0.00095) and associated with poor prognosis (p = 0.036) in COAD patients, highlighting its role as a hub gene of chemoresistance. Ultimately, this signature emerged as an independent prognosis factor for COAD patients (p = 6.48e-06) and expression of model gene are validated by public data and real-world patients. Overall, this bioinformatics study provides valuable insights into the prognostic implications and potential chemotherapy resistance mechanisms associated with TRPs-related genes in colon cancer.

Glutaminase Upregulation As a Mechanism of Chemotherapy Resistance in High-Risk Leukemia

Many types of cancers are characterized by elevated glutamine consumption. Glutaminase is a therapeutic target to arrest cancer cell development. Ikaros (IKZF1) is a DNA-binding, zinc finger protein that functions as a transcriptional regulator and a tumor suppressor in leukemia. Ikaros activity is essential for normal hematopoiesis and immune development and is expressed at high levels in most hematopoietic cells. Deletion of IKZF1 leads to the downregulation and upregulation of many important genes and is a predictor of poor outcomes in leukemia. We hypothesize that upregulation of glutaminase in cancer cells with IKZF1 deletion may be a mechanism whereby high-risk leukemias convey chemotherapy resistance. Conversely, Ikaros may help keep healthy hematopoietic cells in-check by preventing over-expression of glutaminase. To test this hypothesis, we exposed two lines of B-ALL cells to the allosteric and selective glutaminase inhibitor BPTES. One cell line had IKZF1 intact (Nalm-6 scramble) and one had IKZF1 deleted via a CRISPR knockout (Nalm-6 IK KO). Treatments were done in triplicate with an exposure time of 72 hours. WST-1 viability assay was used to obtain an IC50 value for each cell line. Leukemia cells with IKZF1 knocked out had a two-fold higher IC50 than cells with IKZF1 intact. This indicates that IKZF1 deletion may convey chemotherapy resistance by upregulating glutaminase and implies that strategies targeting glutaminase may improve treatment outcomes in high-risk leukemia patients.

Metabolic classification suggests the GLUT1/ALDOB/G6PD axis as a therapeutic target in chemotherapy-resistant pancreatic cancer

Metabolic reprogramming is known as an emerging mechanism of chemotherapy resistance, but the metabolic signatures of pancreatic ductal adenocarcinomas (PDACs) remain unclear. Here, we characterize the metabolomic profile of PDAC organoids and classify them into glucomet-PDAC (high glucose metabolism levels) and lipomet-PDAC (high lipid metabolism levels). Glucomet-PDACs are more resistant to chemotherapy than lipomet-PDACs, and patients with glucomet-PDAC have a worse prognosis. Integrated analyses reveal that the GLUT1/aldolase B (ALDOB)/glucose-6-phosphate dehydrogenase (G6PD) axis induces chemotherapy resistance by remodeling glucose metabolism in glucomet-PDAC. Increased glycolytic flux, G6PD activity, and pyrimidine biosynthesis are identified in glucomet-PDAC with high GLUT1 and low ALDOB expression, and these phenotypes could be reversed by inhibiting GLUT1 expression or by increasing ALDOB expression. Pharmacological inhibition of GLUT1 or G6PD enhances the chemotherapy response of glucomet-PDAC. Our findings uncover potential metabolic heterogeneity related to differences in chemotherapy sensitivity in PDAC and develop a promising pharmacological strategy for patients with chemotherapy-resistant glucomet-PDAC through the combination of chemotherapy and GLUT1/ALDOB/G6PD axis inhibitors.

Identification of co-regulated genes associated with doxorubicin resistance in the MCF-7/ADR cancer cell line.

The molecular mechanism of chemotherapy resistance in breast cancer is not well understood. The identification of genes associated with chemoresistance is critical for a better understanding of the molecular processes driving resistance. This study used a co-expression network analysis of Adriamycin (or doxorubicin)-resistant MCF-7 (MCF-7/ADR) and its parent MCF-7 cell lines to explore the mechanisms of drug resistance in breast cancer. Genes associated with doxorubicin resistance were extracted from two microarray datasets (GSE24460 and GSE76540) obtained from the Gene Expression Omnibus (GEO) database using the GEO2R web tool. The candidate differentially expressed genes (DEGs) with the highest degree and/or betweenness in the co-expression network were selected for further analysis. The expression of major DEGs was validated experimentally using qRT-PCR. We identified twelve DEGs in MCF-7/ADR compared with its parent MCF-7 cell line, including 10 upregulated and 2 downregulated DEGs. Functional enrichment suggests a key role for RNA binding by IGF2BPs and epithelial-to-mesenchymal transition pathways in drug resistance in breast cancer. Our findings suggested that MMP1, VIM, CNN3, LDHB, NEFH, PLS3, AKAP12, TCEAL2, and ABCB1 genes play an important role in doxorubicin resistance and could be targeted for developing novel therapies by chemical synthesis approaches.

Targeting aldehyde dehydrogenase enzymes in combination with chemotherapy and immunotherapy: An approach to tackle resistance in cancer cells.

Modern cancer chemotherapy originated in the 1940s, and since then, many chemotherapeutic agents have been developed. However, most of these agents show limited response in patients due to innate and acquired resistance to therapy, which leads to the development of multi-drug resistance to different treatment modalities, leading to cancer recurrence and, eventually, patient death. One of the crucial players in inducing chemotherapy resistance is the aldehyde dehydrogenase (ALDH) enzyme. ALDH is overexpressed in chemotherapy-resistant cancer cells, which detoxifies the generated toxic aldehydes from chemotherapy, preventing the formation of reactive oxygen species and, thus, inhibiting the induction of oxidative stress and the stimulation of DNA damage and cell death. This review discusses the mechanisms of chemotherapy resistance in cancer cells promoted by ALDH. In addition, we provide detailed insight into the role of ALDH in cancer stemness, metastasis, metabolism, and cell death. Several studies investigated targeting ALDH in combination with other treatments as a potential therapeutic regimen to overcome resistance. We also highlight novel approaches in ALDH inhibition, including the potential synergistic employment of ALDH inhibitors in combination with chemotherapy or immunotherapy against different cancers, including head and neck, colorectal, breast, lung, and liver.

Abstract LB281: HIRA suppression is a mechanism of chemotherapy resistance in ovarian cancer

Abstract Ovarian cancer accounts for the fifth most common cause of cancer death among women, despite being relatively rare. This is in large because majority of cases are diagnosed at advanced stage and frequently recur after primary treatment. Despite numerous efforts to develop effective targeted therapies and immunotherapies for ovarian cancer the standard of care remains chemotherapies. We postulate that part of the problem is the paucity of preclinical research and clinical trials focused on dormant persister ovarian cancer cells that remain after chemotherapy treatments. Emerging evidence supports the idea that persister cancer cells undergo a period of dormancy following chemotherapy which enables their survival and drive late recurrence. Thus, there is dire need to understand the pathways that empower the establishment of dormancy following chemotherapies in ovarian cancer. Epigenetic reprogramming is notoriously known to enable cell fate transitions and the establishment of drug resistance. An important layer of epigenetic regulation frequently overlooked in cancer is the regulation of nucleosome composition via histone variants. Importantly, analysis of data from the human protein atlas revealed that histone H3.3 chaperone, Histone Regulator Protein A (HIRA) expression inversely correlated with poor prognosis, suggesting that HIRA suppression might play a role in the development of chemotherapy resistance. Here, we demonstrate that HIRA is a major regulator of cell fate transitions in ovarian cancer cells in response to chemotherapies. Our data indicates that HIRA levels are suppressed in response chemotherapies in cancer cells. Genetic suppression of HIRA in ovarian cancer cells triggered a non-poliferative state characterized by the induction of canonical dormancy markers (p27, an increase in p38 phosphorylation) and cell cycle arrest. Accordingly, HIRA suppression in these cancer cells renders them less sensitive to the standard of care chemotherapy agent paclitaxel. Together, our data demonstrates that HIRA levels play an important role in controlling cell fate decisions in ovarian cancer and regulate chemotherapy sensitivity. Citation Format: Maya Yasukawa, Stanislav Drapela, Didem Ilter, Mian M. Shahzad, Ana P. Gomes. HIRA suppression is a mechanism of chemotherapy resistance in ovarian cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 2 (Clinical Trials and Late-Breaking Research); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(8_Suppl):Abstract nr LB281.

Use of CRISPR-based screens to identify mechanisms of chemotherapy resistance.

Despite the development of new classes of targeted anti-cancer drugs, the curative treatment of metastatic solid tumors remains out of reach owing to the development of resistance to current chemotherapeutics. Although many mechanisms of drug resistance have been described, there is still a general lack of understanding of the many means by which cancer cells elude otherwise effective chemotherapy. The traditional strategy of isolating resistant clones in vitro, defining their mechanism of resistance, and testing to see whether these mechanisms play a role in clinical drug resistance is time-consuming and in many cases falls short of providing clinically relevant information. In this review, we summarize the use of CRISPR technology, including the promise and pitfalls, to generate libraries of cancer cells carrying sgRNAs that define novel mechanisms of resistance. The existing strategies using CRISPR knockout, activation, and inhibition screens, and combinations of these approaches are described. In addition, specialized approaches to identify more than one gene that may be contributing to resistance, as occurs in synthetic lethality, are described. Although these CRISPR-based approaches to cataloguing drug resistance genes in cancer cells are just beginning to be utilized, appropriately used they promise to accelerate understanding of drug resistance in cancer.