Sensitivity Of Breast Cancer Cells Research Articles

Palmatine, a Bioactive Protoberberine Alkaloid Isolated from Berberis cretica, Inhibits the Growth of Human Estrogen Receptor-Positive Breast Cancer Cells and Acts Synergistically and Additively with Doxorubicin.

Palmatine (PLT) is a natural isoquinoline alkaloid that belongs to the class of protoberberines and exhibits a wide spectrum of pharmacological and biological properties, including anti-cancer activity. The aim of our study was to isolate PLT from the roots of Berberis cretica and investigate its cytotoxic and anti-proliferative effects in vitro alone and in combination with doxorubicine (DOX) using human ER+/HER2− breast cancer cell lines. The alkaloid was purified by column chromatography filled with silica gel NP and Sephadex LH-20 resin developed in the mixture of methanol: water (50:50 v/v) that provided high-purity alkaloid for bioactivity studies. The purity of the alkaloid was confirmed by high resolution mass measurement and MS/MS fragmentation analysis in the HPLC-ESI-QTOF-MS/MS-based analysis. It was found that PLT treatment inhibited the viability and proliferation of breast cancer cells in a dose-dependent manner as demonstrated by MTT and BrdU assays. PLT showed a quite similar growth inhibition on breast cancer cells with IC50 values ranging from 5.126 to 5.805 µg/mL. In contrast, growth of normal human breast epithelial cells was not affected by PLT. The growth inhibitory activity of PLT was related to the induction of apoptosis, as determined by Annexin V/PI staining. Moreover, PLT sensitized breast cancer cells to DOX. Isobolographic analysis revealed synergistic and additive interactions between studied agents. Our studies suggest that PLT can be a potential candidate agent for preventing and treating breast cancer.

Molecular and Clinical Significance of Stanniocalcin-1 Expression in Breast Cancer Through Promotion of Homologous Recombination-Mediated DNA Damage Repair.

Stanniocalcin-1 (STC1) is a glycoprotein hormone whose abnormal expression has been reported to be associated with a variety of tumors, but its function in breast cancer is not well understood. Through modulation of STC1 expression in different breast cancer cell lines, our study found that STC1 could promote the proliferation and growth of breast cancer cells and promote metastasis. Furthermore, STC1 reduced apoptosis induction by irradiation. We also found that STC1 could promote a homologous recombination-mediated DNA damage repair by recruiting BRCA1 to sites of damage. Moreover, STC1 silencing sensitized breast cancer cells to treatment with irradiation (IR), olaparib, or cisplatin in vitro. In clinical settings, the serum concentration of STC1 was higher in breast cancer patients than in healthy women, as detected by enzyme-linked immunosorbent assay (ELISA). In addition, immunohistochemical staining of breast cancer specimens showed that a high expression of STC1 was negatively correlated with recurrence-free survival in breast cancer, indicating that STC1 expression could be used as a predictive marker for a poor prognosis in breast cancer. All these findings indicate that STC1 promotes breast cancer tumorigenesis and that breast cancers with a high level of STC1 are more resistant to treatment, probably through homologous recombination (HR) promotion. Furthermore, combining STC1 inhibition and DNA damage-inducing drugs may be a novel approach to improve the survival of patients with STC1-expressing breast cancer.

USP37 regulates DNA damage response through stabilizing and deubiquitinating BLM.

The human RecQ helicase BLM is involved in the DNA damage response, DNA metabolism, and genetic stability. Loss of function mutations in BLM cause the genetic instability/cancer predisposition syndrome Bloom syndrome. However, the molecular mechanism underlying the regulation of BLM in cancers remains largely elusive. Here, we demonstrate that the deubiquitinating enzyme USP37 interacts with BLM and that USP37 deubiquitinates and stabilizes BLM, thereby sustaining the DNA damage response (DDR). Mechanistically, DNA double-strand breaks (DSB) promotes ATM phosphorylation of USP37 and enhances the binding between USP37 and BLM. Moreover, knockdown of USP37 increases BLM polyubiquitination, accelerates its proteolysis, and impairs its function in DNA damage response. This leads to enhanced DNA damage and sensitizes breast cancer cells to DNA-damaging agents in both cell culture and in vivo mouse models. Collectively, our results establish a novel molecular mechanism for the USP37–BLM axis in regulating DSB repair with an important role in chemotherapy and radiotherapy response in human cancers.

Synergistic apoptotic effect of miR-183-5p and Polo-Like kinase 1 inhibitor NMS-P937 in breast cancer cells

MicroRNAs (miRNAs) are small noncoding RNAs that act as endogenous regulatory molecules targeting specific mRNAs for translational repression. Studies of breast cancer genomics indicate that breast cancer subtypes are distinguished and regulated by specific sets of miRNAs which affect activities such as tumor initiation, progression, and even drug response. Polo-like Kinase 1 (PLK1) is widely considered to be a proto-oncogene due to its increased expression in multiple tumor types, as well as its crucial role in regulating mitosis. Pharmacological inhibition of PLK1 can reduce tumor volume and induce tumor cell death in solid and hematologic malignancies. This prompted us to investigate how PLK1 inhibition with the target-specific inhibitor NMS-P937 would impact breast cancer cells, and how miRNAs may influence the overall response of these cells to this inhibition. We found that miR-183-5p targets PLK1 gene, effectively reducing its protein expression. Such miRNA-driven regulation of PLK1 expression sensitizes breast cancer cells to NMS-P937, resulting in synergistically increased apoptosis. We also show that the miRNA-regulated reduction of PLK1 influences the expression of apoptosis-related key proteins and possibly inducing further indirect PLK1 downmodulation through a DNMT1-p53 axis. These results suggest a potential biologically significant link between the expression of miR-183-5p and the efficacy of PLK1-specific inhibitors in breast cancer cells. Our work further elucidates how miR-183-5p regulates PLK1 gene while also enhancing NMS-P937 effect in breast cancer. Future studies assessing the role of miR-183-5p as a novel biomarker for anti-PLK1 chemotherapy agents are warranted.

Co-expression and prognosis analyses of GLUT1\u20134 and RB1 in breast cancer

BackgroundCurrent treatment methods for patients with triple-negative breast cancer (TNBC) are very limited, and the prognosis of TNBC is relatively poor. It has been reported that glucose transporter 1 (GLUT1) is overexpressed in breast cancer cells; however, its association with the prognosis is mostly unclear. Moreover, retinoblastoma gene 1 (RB1) might be used as a biomarker for the sensitivity of breast cancer cells to GLUT1 inhibitors, which brought us to the hypothesis that there might be a close correlation between the expression of GLUT1–4 and the expression of RB1.MethodsIn this study, we systematically analyzed the co-expression of GLUT1–4 and the influence of GLUT1–4 gene expression on the prognosis of breast cancer using data mining methods. We also explored possible relationships between GLUT1–4 and RB1 expression in breast cancer tissues. We used public databases such as ONCOMINE, GEPIA, LinkedOmics, and COEXPEDIA.ResultsAccording to the results, the mRNA expression of SLC2A1 was significantly higher in breast cancer, while the expression levels of SLC2A2–4 were downregulated. The results also indicate that GLUT1 expression does not have significant influence on the overall survival of patients with breast cancer. The mRNA expression of SLC2A1 and RB1 is significantly correlated, which means that tissues with high RB1 mRNA expression might have relatively higher mRNA expression of SLC2A1; however, further study analyzing their roles in the expression regulation pathways with human samples is needed to verify the hypothesis.ConclusionsThe mRNA expression of SLC2A1 was significantly higher in breast cancer. The overall survival of breast cancer patients wasn’t significantly correlated with GLUT1–4 expression. The mRNA expression of SLC2A1 and RB1 is significantly correlated according to the analysis conducted in LinkedOmics. It provides reference for future possible individualized treatment of TNBC using GLUT1 inhibitors, especially in patients with higher mRNA expression of RB1. Further study analyzing the roles of these two genes in the regulation pathways is needed.

Chromosomal instability sensitizes patient breast tumors to multipolar divisions induced by paclitaxel.

Paclitaxel (Taxol) is a cornerstone of cancer treatment. However, its mechanism of cytotoxicity is incompletely understood and not all patients benefit from treatment. We show that patients with breast cancer did not accumulate sufficient intratumoral paclitaxel to induce mitotic arrest in tumor cells. Instead, clinically relevant concentrations induced multipolar mitotic spindle formation. However, the extent of early multipolarity did not predict patient response. Whereas multipolar divisions frequently led to cell death, multipolar spindles focused into bipolar spindles before division at variable frequency, and maintaining multipolarity throughout mitosis was critical to induce the high rates of chromosomal instability necessary for paclitaxel to elicit cell death. Increasing multipolar divisions in paclitaxel resulted in improved cytotoxicity. Conversely, decreasing paclitaxel-induced multipolar divisions reduced paclitaxel efficacy. Moreover, we found that preexisting chromosomal instability sensitized breast cancer cells to paclitaxel. Both genetic and pharmacological methods of inducing chromosomal instability were sufficient to increase paclitaxel efficacy. In patients, the amount of pretreatment chromosomal instability directly correlated with taxane response in metastatic breast cancer such that patients with a higher rate of preexisting chromosomal instability showed improved response to taxanes. Together, these results support the use of baseline rates of chromosomal instability as a predictive biomarker for paclitaxel response. Furthermore, they suggest that agents that increase chromosomal instability or maintain multipolar spindles throughout mitosis will improve the clinical utility of paclitaxel.

Transcription factor KLF2 enhances the sensitivity of breast cancer cells to cisplatin by suppressing kinase WEE1

ABSTRACT Cisplatin is an effective chemotherapeutic agent in facilitating the inhibition of proliferation, migration, and invasion in cancerous cells. However, the detailed mechanism of the regulation by cisplatin of human breast cancer cells is still unclear. This study aimed to investigate the mechanism of kruppel-like factor 2 (KLF2) transcription factor in cisplatin therapy for breast cancer. RT-qPCR was performed to quantify the expression of KLF2 and WEE1 in clinical tissue samples from breast cancer patients and in MDA-MB-231 cells. ChIP assay and dual-luciferase reporter assay were used to analyze the potential-binding sites of KLF2 and WEE1 promoter. Gain- or loss-of-function approaches were used to manipulate KLF2 and WEE1 in cisplatin-treated MDA-MB-231 cells, and the mechanism of KLF2 in breast cancer was evaluated both via CCK-8 assay, flow cytometry, Transwell assay, and Western blot. Further validation of the KLF2 was performed on nude mouse models. Breast cancer tissues and cells showed a relative decline of KLF2 expression and abundant WEE1 expression. Cisplatin inhibited the proliferation, migration, and invasion of MDA-MB-231 cells. Overexpression of KLF2 enhanced the inhibitory effect of cisplatin on the malignant characteristics of MDA-MB-231 cells in vitro. KLF2 targeted WEE1 and negatively regulated its expression, thus enhancing the sensitivity to cisplatin of breast cancer cells as well as tumor-bearing mice. Overall, these results suggest that KLF2 can potentially inhibit WEE1 expression and sensitize breast cancer cells to cisplatin, thus presenting a promising adjunct treatment.

Docetaxel-loaded PLGA nanoparticles to increase pharmacological sensitivity in MDA-MB-231 and MCF-7 breast cancer cells.

This study aimed to develop docetaxel (DTX) loaded poly(lactic-co-glycolic acid) (PLGA) nanoparticles (DTX-NPs) and to evaluate the different pharmacological sensitivity of NPs to MCF-7 and MDA-MB-231 breast cancer cells. NPs containing DTX or coumarin-6 were prepared by the nanoprecipitation method using PLGA as a polymer and d-α-tocopherol polyethylene glycol 1000 succinate (TPGS) as a surfactant. The physicochemical properties of NPs were characterized. In vitro anticancer effect and cellular uptake were evaluated in breast cancer cells. The particle size and zeta potential of the DTX-NPs were 160.5 ± 3.0 nm and –26.7 ± 0.46 mV, respectively. The encapsulation efficiency and drug loading were 81.3 ± 1.85% and 10.6 ± 0.24%, respectively. The in vitro release of DTX from the DTX-NPs was sustained at pH 7.4 containing 0.5% Tween 80. The viability of MDA-MB-231 and MCF-7 cells with DTX-NPs was 37.5 ± 0.5% and 30.3 ± 1.13%, respectively. The IC50 values of DTX-NPs were 3.92- and 6.75-fold lower than that of DTX for MDA-MB-231 cells and MCF-7 cells, respectively. The cellular uptake of coumarin-6-loaded PLGA-NPs in MCF-7 cells was significantly higher than that in MDA-MB-231 cells. The pharmacological sensitivity in breast cancer cells was higher on MCF-7 cells than on MDA-MB-231 cells. In conclusion, we successfully developed DTX-NPs that showed a great potential for the controlled release of DTX. DTX-NPs are an effective formulation for improving anticancer effect in breast cancer cells.

TGF-β-Induced TMEPAI Promotes Epithelial–Mesenchymal Transition in Doxorubicin-Treated Triple-Negative Breast Cancer Cells via SMAD3 and PI3K/AKT Pathway Alteration

IntroductionEpithelial–mesenchymal transition (EMT) and overexpression of drug efflux transporters have been reported to cause doxorubicin resistance. Our previous study indicated that TMEPAI (transmembrane prostate androgen-induced protein) attenuated doxorubicin sensitivity in triple-negative breast cancer cells. However, how TMEPAI contributes to doxorubicin resistance in TNBC remains unclear. Thus, the present study aimed to elucidate the mechanism of TMEPAI in doxorubicin resistance in triple-negative breast cancer cells.MethodsWe used BT549, triple-negative cells wild type (WT), and BT549 TMEPAI knock-out. Both cells were treated with TGF-β 2 ng/mL for 24 hours, followed by TGF-β 2 ng/mL and doxorubicin 12.9 nM for another 24 hours. Afterward, the cells were harvested and counted. Cells were further lysed and used for RT-PCR and Western blot analysis. We determined the expression levels of proliferation, apoptosis, EMT markers, and drug efflux transporters. Additionally, we investigated the expressions of PI3K as well as SMAD3 and AKT phosphorylation.ResultsTNBC cells were shown to be less sensitive to doxorubicin in the presence of TMEPAI. TMEPAI was shown to alleviate the mRNA expressions of apoptosis markers: Bax, Bcl2, Caspase-3, and Caspase-9. Our results indicated that the presence of TMEPAI greatly amplifies EMT and increases drug efflux transporter expressions after doxorubicin treatment. Furthermore, our findings demonstrated that TMEPAI reduced the action of doxorubicin in inhibiting SMAD3 phosphorylation. TMEPAI was also shown to modify the effect of doxorubicin by reducing PI3K expressions and Akt phosphorylation in triple-negative breast cancer cells.ConclusionOur findings indicate that TMEPAI promotes EMT and drug efflux transporters at least in part by shifting doxorubicin action from SMAD3 phosphorylation reduction to PI3K/AKT inhibition in triple-negative breast cancer cells.

EMP3 negatively modulates breast cancer cell DNA replication, DNA damage repair, and stem-like properties

Enhanced DNA damage repair capacity attenuates cell killing of DNA-damaging chemotherapeutic agents. In silico analysis showed that epithelial membrane protein 3 (EMP3) is associated with favorable survival, and negatively regulates cell cycle S-phase. Consistently, loss and gain of function studies demonstrated that EMP3 inhibits breast cancer cell S-phage entry, DNA replication, DNA damage repair, and stem-like properties. Moreover, EMP3 blocks Akt-mTOR signaling activation and induces autophagy. EMP3 negatively modulates BRCA1 and RAD51 expression, indicating EMP3 suppresses homologous recombination repair of DNA double-strand breaks. Accordingly, EMP3 sensitizes breast cancer cells to the DNA-damaging drug Adriamycin. EMP3 downregulates YTHDC1, a RNA-binding protein involved in m6a modification, which at least in part mediates the effects of EMP3 on breast cancer cells. Taken together, these data indicate that EMP3 is a putative tumor suppressor in breast cancer, and EMP3 downregulation may be responsible for breast cancer chemoresistance.

Complement inhibitor CSMD1 modulates epidermal growth factor receptor oncogenic signaling and sensitizes breast cancer cells to chemotherapy

BackgroundHuman CUB and Sushi multiple domains 1 (CSMD1) is a large membrane-bound tumor suppressor in breast cancer. The current study aimed to elucidate the molecular mechanism underlying the effect of CSMD1 in highly invasive triple negative breast cancer (TNBC).MethodsWe examined the antitumor action of CSMD1 in three TNBC cell lines overexpressing CSMD1, MDA-MB-231, BT-20 and MDA-MB-486, in vitro using scanning electron microscopy, proteome array, qRT-PCR, immunoblotting, proximity ligation assay, ELISA, co-immunoprecipitation, immunofluorescence, tumorsphere formation assays and flow cytometric analysis. The mRNA expression pattern and clinical relevance of CSMD1 were evaluated in 3520 breast cancers from a modern population-based cohort.ResultsCSMD1-expressing cells had distinct morphology, with reduced deposition of extracellular matrix components. We found altered expression of several cancer-related molecules, as well as diminished expression of signaling receptors including Epidermal Growth Factor Receptor (EGFR), in CSMD1-expressing cells compared to control cells. A direct interaction of CSMD1 and EGFR was identified, with the EGF-EGFR induced signaling cascade impeded in the presence of CSMD1. Accordingly, we detected increased ubiquitination levels of EGFR upon activation in CSMD1-expressing cells, as well as increased degradation kinetics and chemosensitivity. Accordingly, CSMD1 expression rendered tumorspheres pretreated with gefitinib more sensitive to chemotherapy. In addition, higher mRNA levels of CSMD1 tend to be associated with better outcome of triple negative breast cancer patients treated with chemotherapy.ConclusionsOur results indicate that CSMD1 cross-talks with the EGFR endosomal trafficking cascade in a way that renders highly invasive breast cancer cells sensitive to chemotherapy. Our study unravels one possible underlying molecular mechanism of CSMD1 tumor suppressor function and may provide novel avenues for design of better treatment.

Emodin-loaded polymer-lipid hybrid nanoparticles enhance the sensitivity of breast cancer to doxorubicin by inhibiting epithelial\u2013mesenchymal transition

BackgroundThe role of epithelial–mesenchymal transition (EMT) involved in breast cancer metastasis and chemoresistance has been increasingly recognized. However, it is necessary to search for more effective strategies to inhibit EMT thereby increase the sensitivity of breast cancer cells to chemotherapy drugs. Emodin has a potential in overcoming tumor drug resistance and restraining the development of EMT, but the poor internalization into breast cancer cells limited the application.ResultsMCF-7/ADR cells have more EMT characteristics than MCF-7 cell. EMT in MCF-7/ADR cells promotes the development of drug resistance via apoptosis resistance and facilitating the expression of P-gp. The anti-cancer effect of DOX enhanced by the decreasing of drug resistance protein P-gp and apoptosis-related proteins after EMT inhibited in MCF-7/ADR cells. E-PLNs increase the cellular uptake of EMO and restore DOX sensitivity in MCF-7/ADR cells by inhibiting EMT.ConclusionE-PLNs inhibit EMT to enhance the sensitivity of breast cancer to DOX. The combination of E-PLNs and DOX can improve the efficacy of DOX in the treatment of breast cancer, which provides a new method to prevent or delay clinical drug resistance.

CHFR-mediated degradation of RNF126 confers sensitivity to PARP inhibitors in triple-negative breast cancer cells

Ring-finger protein 126 (RNF126), an E3 ubiquitin ligase, plays crucial roles in various biological processes, including cell proliferation, DNA damage repair, and intracellular vesicle trafficking. Whether RNF126 is modulated by posttranslational modifications is poorly understood. Here, we show that PARP1 interacts with and poly(ADP)ribosylates RNF126, which then recruits the PAR-binding E3 ubiquitin ligase CHFR to promote ubiquitination and degradation of RNF126. Moreover, RNF126 is required for the activation of ATR-Chk1 signaling induced by either irradiation (IR) or a PARP inhibitor (PARPi), and depletion of RNF126 increases the sensitivity of triple-negative breast cancer (TNBC) cells to PARPi treatment. Our findings suggest that PARPi-mediated upregulation of RNF126 protein stability contributes to TNBC cell resistance to PARPi. Therefore, targeting the E3 ubiquitin ligase RNF126 may be a novel treatment for overcoming the resistance of TNBC cells to PARPi in clinical trials.

The Synergistic Effects of Celastrol in combination with Tamoxifen on Apoptosis and Autophagy in MCF-7 Cells.

Breast cancer is one of the most common cancers among females and is associated with high mortality and morbidity rates. Several studies have demonstrated that combination treatments with natural products and tamoxifen can improve the sensitivity and cytotoxicity of oestrogen-positive breast cancer cells in response to tamoxifen. Celastrol, a triterpene from traditional Chinese medicine, has been proven to exert significant anticancer effects on various cancers. Our study is aimed at exploring the interactive antitumour effects of celastrol combined with tamoxifen and the potential underlying anticancer mechanisms in MCF-7 cells. The results from MTT assays, isobolographic analyses, and clonogenic cell survival assays revealed that a combination of celastrol and tamoxifen exerted synergistic cytotoxic effects in MCF-7 cells. The results from Annexin V/PI staining and flow cytometry analysis suggested that celastrol enhanced tamoxifen-mediated apoptosis. In addition, exposure to a combination of celastrol and tamoxifen inhibited cell proliferation by causing G1 phase cell cycle arrest. Moreover, the distribution of LC3 was monitored by immunofluorescence, and the changes in the LC3II and P62 levels detected by western blot analysis suggested that celastrol in combination with tamoxifen triggered autophagy. Furthermore, the decrease in p-Akt and p-mTOR in MCF-7 cells, along with the increase in the autophagy marker proteins LC3II and P62, suggested that the Akt/mTOR pathway might be involved in the triggering of cell autophagy by the combination treatment. However, in an MCF-7-implanted nude mouse model, it was possible to detect significantly decreased tumour volumes and tumour weights and decreased p-Akt and p-mTOR protein expression in the celastrol+tamoxifen group. Therefore, our study provides the first evidence that celastrol combined with tamoxifen exerts synergistic anticancer effects by inducing apoptosis and autophagy in MCF-7 cells. Considering the urgent need for novel therapeutic strategies in anticancer therapy, this combinatorial approach is worthy of further investigation.

SLC1A5 co-expression with TALDO1 associates with endocrine therapy failure in estrogen receptor-positive breast cancer

PurposeIdentification of effective biomarkers for the benefit of endocrine treatment and understanding the molecular pathways that contribute to the development of resistance are of crucial importance to the management of luminal breast cancer. The amino acid transporter SLC1A5 has emerging importance as a prognostic marker and potential therapeutic target in various types of cancer. This study aims to investigate its role in luminal breast cancer as a potential predictive marker for endocrine treatment.MethodsSLC1A5 expression was assessed at the transcriptomic and proteomic levels in large, well-characterized cohorts of luminal breast cancer. The sensitivity to endocrine therapy after SLC1A5 knockdown was investigated in vitro, using MCF7 and MDA-MB-175 cell lines. Bioinformatic analyses were performed to study the interacting networks of SLC1A5 and to identify a key co-expressed gene with SLC1A5.ResultsHere, we showed that patients with tumors that highly expressed SLC1A5 associated with a high risk of relapse after endocrine treatment. In vitro, depletion of SLC1A5 increases the sensitivity of luminal breast cancer cells to tamoxifen. TALDO1 was identified as key co-expressed gene with SLC1A5, and in vitro knockdown of SLC1A5 showed reduction in TALDO1 expression. Indeed, TALDO1 was associated with poor clinical outcomes in patients who were subject to endocrine therapy.ConclusionThese findings suggest that metabolic alterations, particularly the interaction between the key amino acid transporter SLC1A5 and metabolic enzyme TALDO1, could affect the sensitivity of endocrine therapy. This study demonstrated the prognostic value of both SLC1A5 and TALDO1 as biomarkers in luminal breast cancer.

KMT2C is a potential biomarker of prognosis and chemotherapy sensitivity in breast cancer.

Epigenetic regulation plays critical roles in cancer progression, and high-frequency mutations or expression variations in epigenetic regulators have been frequently observed in tumorigenesis, serving as biomarkers and targets for cancer therapy. Here, we aimed to explore the function of epigenetic regulators in breast cancer. The mutational landscape of epigenetic regulators in breast cancer samples was investigated based on datasets from the Cancer Genome Atlas. The Kaplan-Meier method was used for survival analysis. RNA sequencing (RNA-seq) in MCF-7 cells transfected with control siRNA or KMT2C siRNA was performed. Quantitative reverse transcription-PCR and chromatin immunoprecipitation were used to validate the RNA-seq results. Among the 450 epigenetic regulators, KMT2C was frequently mutated in breast cancer samples. The tumor mutational burden (TMB) was elevated in breast cancer samples with KMT2C mutations or low KMT2C mRNA levels compared to their counterparts with wild-type KMT2C or high KMT2C mRNA levels. Somatic mutation and low expression of KMT2C were independently correlated with the poor overall survival (OS) and disease-free survival (DFS) of the breast cancer samples, respectively. RNA-seq analysis combined with chromatin immunoprecipitation and qRT-PCR assays revealed that the depletion of KMT2C remarkably affected the expression of DNA damage repair-related genes. More importantly, the low expression of KMT2C was related to breast cancer cell sensitivity to chemotherapy and longer OS of breast cancer patients who underwent chemotherapy. We conclude that KMT2C could serve as a potential biomarker of prognosis and chemotherapy sensitivity by affecting the DNA damage repair-related genes of breast cancer.

A radiosensitizer, gallotannin-rich extract from Bouea macrophylla seeds, inhibits radiation-induced epithelial-mesenchymal transition in breast cancer cells

BackgroundRadioresistance can pose a significant obstacle to the effective treatment of breast cancers. Epithelial–mesenchymal transition (EMT) is a critical step in the acquisition of stem cell traits and radioresistance. Here, we investigated whether Maprang seed extract (MPSE), a gallotannin-rich extract of seed from Bouea macrophylla Griffith, could inhibit the radiation-induced EMT process and enhance the radiosensitivity of breast cancer cells.MethodsBreast cancer cells were pre-treated with MPSE before irradiation (IR), the radiosensitizing activity of MPSE was assessed using the colony formation assay. Radiation-induced EMT and stemness phenotype were identified using breast cancer stem cells (CSCs) marker (CD24−/low/CD44+) and mammosphere formation assay. Cell motility was determined via the wound healing assay and transwell migration. Radiation-induced cell death was assessed via the apoptosis assay and SA-β-galactosidase staining for cellular senescence. CSCs- and EMT-related genes were confirmed by real-time PCR (qPCR) and Western blotting.ResultsPre-treated with MPSE before irradiation could reduce the clonogenic activity and enhance radiosensitivity of breast cancer cell lines with sensitization enhancement ratios (SERs) of 2.33 and 1.35 for MCF7 and MDA-MB231cells, respectively. Pretreatment of breast cancer cells followed by IR resulted in an increased level of DNA damage maker (γ-H2A histone family member) and enhanced radiation-induced cell death. Irradiation induced EMT process, which displayed a significant EMT phenotype with a down-regulated epithelial marker E-cadherin and up-regulated mesenchymal marker vimentin in comparison with untreated breast cancer cells. Notably, we observed that pretreatment with MPSE attenuated the radiation-induced EMT process and decrease some stemness-like properties characterized by mammosphere formation and the CSC marker. Furthermore, pretreatment with MPSE attenuated the radiation-induced activation of the pro-survival pathway by decrease the expression of phosphorylation of ERK and AKT and sensitized breast cancer cells to radiation.ConclusionMPSE enhanced the radiosensitivity of breast cancer cells by enhancing IR-induced DNA damage and cell death, and attenuating the IR-induced EMT process and stemness phenotype via targeting survival pathways PI3K/AKT and MAPK in irradiated breast cancer cells. Our findings describe a novel strategy for increasing the efficacy of radiotherapy for breast cancer patients using a safer and low-cost natural product, MPSE.

Exploiting off-target effects of estrogen deprivation to sensitize estrogen receptor negative breast cancer to immune killing

BackgroundThere are highly effective treatment strategies for estrogen receptor (ER)+, progesterone receptor (PR)+, and HER2+ breast cancers; however, there are limited targeted therapeutic strategies for the 10%–15% of women who...

Abstract 645: Network-based assessment of HDAC6 activity is highly predictive of pre-clinical and clinical responses to the HDAC6 inhibitor ricolinostat

Abstract Despite the anticancer activity of pan-histone deacetylase (HDAC) inhibitors, their clinical use has been limited due to toxicity. However, the development of more specific inhibitors that selectively inhibit individual HDACs is emerging as a novel and well-tolerated alternative. Here, we present the results of the first clinical trial evaluating the activity of ricolinostat (the leading HDAC6 inhibitor) in breast cancer (BC) patients. We have developed a computational network-based algorithm to evaluate the activity of the HDAC6 protein, based on the enrichment of its transcriptional targets in differentially expressed genes (HDAC6 score). Through preclinical in vitro and in vivo studies, we confirmed that the HDAC6 score can stratify the sensitivity of BC cells to ricolinostat treatment and may thus have value as a predictive biomarker. Moreover, analysis of ~3,000 primary human breast cancers showed that ~30% of them present high HDAC6 scores. Based on these results, we designed a phase Ib clinical trial to evaluate the activity of ricolinostat plus nab-paclitaxel in metastatic BC patients. Study results showed that the two agents can be safely combined, that clinical activity is identified specifically in patients with HR+/HER2- disease, and that the HDAC6 score was predictive of response. Expansion of our analysis to other tumor types identified multiple cohorts enriched in high HDAC6 score samples. These results suggest that the HDAC6 score may provide an effective, CLIA certified predictive biomarker of ricolinostat sensitivity in multiple human cancers. Citation Format: Qingfei Pan, Tizita Zeleke, Cody Chiuzan, Maika Onishi, Mariano Alvarez, Erin Honan, Min Yang, Pei Ling Chia, Partha Mukhopadhyay, Sean Kelly, Ruby Wu, Kathleen Fenn, Meghna Trivedi, Melissa Accordino, Katherine Crew, Dawn Hershman, Matthew Maurer, Simon Jones, Andrea Califano, Kevin Kalinsky, Jiyang Yu, Jose Silva. Network-based assessment of HDAC6 activity is highly predictive of pre-clinical and clinical responses to the HDAC6 inhibitor ricolinostat [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 645.

LncRNA NEAT1 promotes the Taxol resistance of breast cancer via sponging the miR-23a-3p-FOXA1 axis.

Breast cancer is the most prevalent malignancy among women worldwide. Paclitaxel (Taxol) is a widely applied chemotherapeutic agent against breast cancer. Although Taxol therapy has achieved improvements recently, development of chemoresistance of breast cancer patients is a major obstacle, leading to therapeutic failure. Long non-coding RNAs (lncRNAs) play pivotal roles in tumorigenesis and progresses of breast cancer. However, the biological roles and molecular targets of lncRNA NEAT1 in Taxol-resistant breast cancer remain unclear. Here, we report that NEAT1 is significantly upregulated in breast tumors and cell lines. In addition, silencing NEAT1 effectively sensitizes breast cancer cells to Taxol. Bioinformatical analysis and luciferase assay demonstrated that miR-23a-3p could be sponged and downregulated by NEAT1. We demonstrated that miR-23a-3p was downregulated and functioned as a tumor suppressor in breast cancer. Furthermore, in the established Taxol-resistant MDA-MB-231 breast cancer cell line, we detected significantly increased NEAT1 expression and downregulated miR-23a-3p expression. Importantly, FOXA1 was identified and validated as a direct target of miR-23a-3p in breast cancer cells. Rescue experiments demonstrated that the restoration of miR-23a-3p in NEAT1-overexpressing Taxol-resistant breast cancer cells successfully overcame the NEAT1-promoted Taxol resistance. Taken together, our results revealed the clinical roles and molecular mechanisms for the NEAT1-mediated chemoresistance, providing new insights into the development of non-coding RNA-based therapeutic strategies for enhancing the anti-cancer effects of traditional chemotherapeutic drugs.