Chemosensitivity Of Triple-negative Breast Cancer Research Articles

Abstract 7198: A small molecule Notch1 inhibitor (ASR490) restores chemosensitivity in triple-negative breast cancer

Abstract Metastatic triple-negative Breast cancer (mTNBC) is an aggressive and often a chemo resistant disease for which no effective druggable target has yet been identified. We and others reported that the aberrant expression of neurogenic locus Notch homolog protein 1 (Notch1) serves as a molecular signature for TNBC. Hence, we postulated that pharmacologically targeting Notch1 in conjunction with a standard chemotherapeutic agent (Doxorubicin: DXR) may completely eradicate TNBC growth and overcome systemic and debilitating toxicity. Hence, this study aims to elucidate the role of our recently discovered notch1 inhibitor ASR490 and its ability to chemosensitize TNBC without significant systemic toxicity. In our results, pretreatment of 1/10 th of the inhibitory concentration of ASR490 combined with 1/10 th or 1/20th of DXR significantly inhibited the growth of TNBC cells (MDA-MB-231 and BT549). Notably, DXR treatment induced Notch1 activation which led to chemoresistance in TNBC; however, co-treatment with the Notch1 inhibitor ASR490, led to the downregulation of Notch1 activation and eradication of the cell viability and clonogenicity of the TNBC cells. Further, molecular analysis suggested that pretreatment of 1/10th of ASR490 facilitates DXR-mediated sensitivity, by inhibiting the DNA repair pathway and upregulating (cleaved) caspase 3, (cleaved) caspase-9 and poly (ADP-Ribose) polymerase (PARP)-mediated apoptosis. Similarly, the combination effectively blocked the epithelial and mesenchymal transition (EMT) regulators and suppressed metastatic properties of MDA-MB231 and BT-549 cells. Moreover, combining ASR490(1/10th) and DXR (1/20th) significantly eradicated xenotransplanted TNBC tumors compared to ASR490 or DXR alone. In addition to being effective at inhibiting tumor growth, the significantly lower dose requirements of DXR and ASR490 in combination makes it a highly safe therapeutic modality. These findings suggest that aberrant activation of Notch1 is responsible for TNBC chemoresistance and concomitantly inhibiting Notch1 activation is an effective therapeutic strategy to restore chemosensitivity in TNBC. Citation Format: Neha Tyagi, Balaji Chandrasekaran, Ashish Tyagi, Balpreet Singh, Megha Chandran, Amandeep Singh, Arun Sharma, Chendil Damodaran. A small molecule Notch1 inhibitor (ASR490) restores chemosensitivity in triple-negative breast cancer [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 7198.

SIRT3 Expression Predicts Overall Survival and Neoadjuvant Chemosensitivity in Triple-Negative Breast Cancer.

The Sirtuin (SIRT) family consists of seven evolutionary conserved NAD-dependent deacetylases that play important roles in various cancers, including breast cancer (BC). SIRTs expression has been reported to have prognostic value in BC, but these studies used limited sample size and yielded inconsistent conclusions. This study evaluated the association of SIRT3 and other SIRT family members with survival and neoadjuvant chemotherapy outcomes. BC patients' data was obtained from the TCGA-BRCA, METABRIC and GEO databases, comprising 4336 samples. SIRTs expression and overall survival (OS) were analyzed using Kaplan-Meier analysis and Cox proportional hazards regression. SIRT3 expression levels were compared between pathologic complete response (pCR) and non-pCR groups after neoadjuvant chemotherapy in triple-negative breast cancer (TNBC). Protein-protein interaction networks were constructed using the STRING database. Gene set enrichment analysis (GSEA) was performed to explore potential functions of SIRT3. Through systematic analysis of SIRTs expression and OS of BC using three independent cohorts: TCGA-BRCA, METABRIC and GSE16446, we found that high SIRT3 expression was significantly associated with worse OS in TNBC in the TCGA-BRCA cohort, which was validated in the METABRIC and GSE16446 cohorts. SIRT3 expression was correlated with BC subtypes and American Joint Committee on Cancer (AJCC) T stage, but not with age-at-diagnosis, race, or tumor stage. Moreover, TNBC patients with higher SIRT3 expression had lower pCR rates after neoadjuvant chemotherapy (p = 6.40e-03) and SIRT3 expression was significantly lower in the pCR group than in the non-pCR group in TNBC (p = 4.2e-03). GSEA indicated that SIRT3 was involved in drug-related pathways such as oxidative phosphorylation, metabolism of xenobiotics by cytochrome P450, and drug metabolism. Our study suggests that SIRT3 is a potential biomarker for both OS and neoadjuvant chemosensitivity in TNBC. It may also assist in selecting suitable candidates and treatment options for TNBC patients.

Metadherin inhibits chemosensitivity of triple-negative breast cancer to paclitaxel via activation of AKT/GSK-3β signaling pathway.

Triple-negative breast cancer (TNBC) has an aggressive clinical course, and paclitaxel (PTX)-based chemotherapy remains the main therapeutic drug. Metadherin (MTDH) acts as an oncogene that regulates proliferation, invasion, metastasis, and chemoresistance. This study aimed to investigate whether TNBC chemosensitivity to PTX was related to the MTDH/AKT/glycogen synthase kinase-3beta (GSK-3β) pathway. Clinical baseline characteristics and immunohistochemistry (IHC) were used to evaluate the expression and prognosis of MTDH and AKT (protein kinase B, PKB) in TNBC patient samples. MTDH shRNA, MTDH overexpression vector, MK-2206, and PTX intervention were used in cell models and mouse tumor-bearing models. Afterwards, mRNA and protein levels were assessed using quantitative real-time polymerase chain reaction and Western blot. Evaluate the level of tumor cell apoptosis and cell cycle using flow cytometry. Cell viability was detected using Cell Count Kit 8. The invivo imaging system is used to analyze the growth of tumors. We found that higher expression of MTDH or AKT resulted in poorer disease-free survival and a lower Miller-Payne grade. MTDH promotes cell proliferation and increases p-AKT and p-GSK-3β expression in TNBC cells. Notably, suppression of AKT terminated MTDH overexpression-induced cell proliferation and apoptosis. MTDH knockdown or the AKT inhibitor MK2206 reduced the p-AKT and p-GSK-3β ratio, reduced cell viability and proliferation, increased cell apoptosis, and increased chemosensitivity to PTX. Invivo, xenograft tumors of an MTDH knockdown+MK2206 group treated with PTX were the smallest compared to other groups. In short, MTDH inhibits TNBC chemosensitivity to PTX by activating the AKT/GSK-3β signaling pathway.

KLHL29-mediated DDX3X degradation promotes chemosensitivity by abrogating cell cycle checkpoint in triple-negative breast cancer

Triple-negative breast cancer (TNBC) is a heterogeneous breast cancer subtype and accounts for approximately 15–20% of breast cancer cases. In this study, we identified KLHL29, which is an understudied member of the Kelch-like gene family, as a crucial tumor suppressor that regulates chemosensitivity in TNBC. KLHL29 expression was significantly downregulated in breast cancer tissues compared with adjacent normal tissues, and low levels of KLHL29 were associated with unfavorable prognoses. Ectopic KLHL29 suppressed, while depleting KLHL29 promoted, the growth, proliferation, migration, and invasion of TNBC. Mechanistically, KLHL29 recruited the CUL3 E3-ligase to the RNA-binding protein DDX3X, leading to the proteasomal degradation of the latter. This downregulation of DDX3X resulted in the destabilization of CCND1 mRNA and the consequent cell cycle arrest at G0/G1 phase. Remarkably, the DDX3X inhibitor RK33 combined with platinum-based chemotherapy can synergistically suppress TNBC that usually expresses low levels of KLHL29 and high levels of DDX3X using cancer cell-derived xenograft and patient-derived organoids models. Altogether, we uncovered the potential role for the KLHL29-DDX3X signaling cascade in the regulation of TNBC progression, thus providing a promising combination strategy for overcoming TNBC chemoresistance.

Development of Gene Expression-Based Random Forest Model for Predicting Neoadjuvant Chemotherapy Response in Triple-Negative Breast Cancer.

Simple SummaryOnly 20–50% of patients with triple negative breast cancer achieve a pathological complete response from neoadjuvant chemotherapy, a strong indicator of patient survival. Therefore, there is an urgent need for a reliable predictive model of the patient’s pathological complete response prior to actual treatment. The purpose of this study was to develop such a model based on random forest recursive feature elimination and to benchmark the performance of the proposed model against existing predictive models. Our study suggests that an 86-gene-based random forest model associated to DNA repair and cell cycle mechanisms can provide reliable predictions of neoadjuvant chemotherapy response in patients with triple negative breast cancer.Neoadjuvant chemotherapy (NAC) response is an important indicator of patient survival in triple negative breast cancer (TNBC), but predicting chemosensitivity remains a challenge in clinical practice. We developed an 86-gene-based random forest (RF) classifier capable of predicting neoadjuvant chemotherapy response (pathological Complete Response (pCR) or Residual Disease (RD)) in TNBC patients. The performance of pCR classification of the proposed model was evaluated by Receiver Operating Characteristic (ROC) curve and Precision Recall (PR) curve. The AUROC and AUPRC of the proposed model on the test set were 0.891 and 0.829, respectively. At a predefined specificity (>90%), the proposed model shows a superior sensitivity compared to the best performing reported NAC response prediction model (69.2% vs. 36.9%). Moreover, the predicted pCR status by the model well explains the distance recurrence free survival (DRFS) of TNBC patients. In addition, the pCR probabilities of the proposed model using the expression profiles of the CCLE TNBC cell lines show a high Spearman rank correlation with cyclophosphamide sensitivity in the TNBC cell lines (SRCC , p-value ). Associations between the 86 genes and DNA repair/cell cycle mechanisms were provided through function enrichment analysis. Our study suggests that the random forest-based prediction model provides a reliable prediction of the clinical response to neoadjuvant chemotherapy and may explain chemosensitivity in TNBC.

Targeting Thymidylate Synthase Enhances the Chemosensitivity of Triple-Negative Breast Cancer Towards 5-FU-Based Combinatorial Therapy.

BackgroundThe ongoing treatment modalities for breast cancer (BC) primarily rely on the expression status of ER, PR and HER-2 receptors in BC tissues. Our strategy of chemosensitization provides new insights to counter chemoresistance, a major obstacle that limits the benefits of chemotherapy of mammary cancers.MethodsBy utilizing a murine breast cancer model employing NSG mice bearing orthotopic triple-negative breast cancer (TNBC) xenografts, we have evaluated the ability of phytochemical curcumin in chemosensitizing BC to 5-Fluorouracil (5-FU) chemotherapy and the differential modulations of cellular events in response to this strategy, independent of their receptor status.ResultsA significant synergistic antitumor potential was observed in the murine model with a sub-optimal dose treatment of 5-FU plus curcumin, as evaluated by a reduction in the tumor-related parameters. We authenticated the pivotal role of thymidylate synthase (TS) in regulating the 5-FU–curcumin synergism using the TNBC pre-clinical model. Our study also confirmed the pharmacological safety of this chemotherapeutic plus phytoactive combination using acute and chronic toxicity studies in Swiss albino mice. Subsequently, the molecular docking analysis of curcumin binding to TS demonstrated the affinity of curcumin towards the cofactor-binding site of TS, rather than the substrate-binding site, where 5-FU binds. Our concomitant in vivo and in silico evidence substantiates the superior therapeutic index of this combination.ConclusionThis is the first-ever pre-clinical study portraying TS as the critical target of combinatorial therapy for mammary carcinomas and therefore we recommend its clinical validation, especially in TNBC patients, who currently have limited therapeutic options.

Highly penetrating nanobubble polymer enhances LINC00511-siRNA delivery for improving the chemosensitivity of triple-negative breast cancer.

Ultrasound-mediated nanobubble destruction (UMND), which can utilize the physical energy of ultrasound irradiation to improve the transfer efficiency to target cells is becoming one of the most promising carriers for gene delivery. The purpose of this study was to establish cell-penetrating peptide (CPP)-loaded nanobubbles (CNBs) connected with long intergenic nonprotein coding RNA 00511-small interfering RNA (LINC00511-siRNA) and evaluate its feasibility for improving the chemosensitivity of triple-negative breast cancer in vitro. First, fluorescence imaging confirmed the loading of siLINC00511 on CNBs, and the CNBs-siLINC00511 were characterized by the Zetasizer Nano ZS90 analyzer and transmission electron microscopy. Next, cell counting kit 8 assay was used to detect the inhibitory activity of cisplatin on the proliferation of MDA-MB-231 cells, and the 50% inhibition concentration value before and after transfer was calculated. Finally, the silencing effect of siLINC00511 was evaluated in vitro using an apoptosis assay, transwell assay, real time-PCR and western blotting. UMND combined with CNBs could effectively transfer the siRNA to MDA-MB-231 cells, thus evidently reducing the expression of LINC00511. Furthermore, inhibitory activity of cisplatin on MDA-MB-231 cells was enhanced after downregulation of LINC00511 expression. Downregulation of LINC00511 alters expression of cell cycle-related (CDK 6) and apoptosis-related (Bcl-2 and Bax) proteins in MDA-MB-231 cells. These results suggested that siRNA-CNBs may be an ideal vector for the treatment of tumors, with high efficiency RNA interference under the combined action of UMND. It may provide a new therapeutic method for triple negative breast cancer.

PRKCQ inhibition enhances chemosensitivity of triple-negative breast cancer by regulating Bim

BackgroundProtein kinase C theta, (PRKCQ/PKCθ) is a serine/threonine kinase that is highly expressed in a subset of triple-negative breast cancers (TNBC) and promotes their growth, anoikis resistance, epithelial-mesenchymal transition (EMT), and invasion. Here, we show that PRKCQ regulates the sensitivity of TNBC cells to apoptosis triggered by standard-of-care chemotherapy by regulating levels of pro-apoptotic Bim.MethodsTo determine the effects of PRKCQ expression on chemotherapy-induced apoptosis, shRNA and cDNA vectors were used to modulate the PRKCQ expression in MCF-10A breast epithelial cells or triple-negative breast cancer cells (MDA-MB231Luc, HCC1806). A novel PRKCQ small-molecule inhibitor, 17k, was used to inhibit kinase activity. Viability and apoptosis of cells treated with PRKCQ cDNA/shRNA/inhibitor +/-chemotherapy were measured. Expression levels of Bcl2 family members were assessed.ResultsEnhanced expression of PRKCQ is sufficient to suppress apoptosis triggered by paclitaxel or doxorubicin treatment. Downregulation of PRKCQ also enhanced the apoptosis of chemotherapy-treated TNBC cells. Regulation of chemotherapy sensitivity by PRKCQ mechanistically occurs via regulation of levels of Bim, a pro-apoptotic Bcl2 family member; suppression of Bim prevents the enhanced apoptosis observed with combined PRKCQ downregulation and chemotherapy treatment. Regulation of Bim and chemotherapy sensitivity is significantly dependent on PRKCQ kinase activity; overexpression of a catalytically inactive PRKCQ does not suppress Bim or chemotherapy-associated apoptosis. Furthermore, PRKCQ kinase inhibitor treatment suppressed growth, increased anoikis and Bim expression, and enhanced apoptosis of chemotherapy-treated TNBC cells, phenocopying the effects of PRKCQ downregulation.ConclusionsThese studies support PRKCQ inhibition as an attractive therapeutic strategy and complement to chemotherapy to inhibit the growth and survival of TNBC cells.

Dual TGF-β and AURKA targeting enhances chemosensitivity in triple-negative breast cancer.

e13106 Background: Chemotherapy resistance remains a significant barrier in the effective treatment of patients with triple negative breast cancer (TNBC). TGF-β signaling is a well characterized oncogenic pathway in TNBC that promotes chemoresistance by inducing epithelial to mesenchymal transition (EMT) and tumor stemness. Aurora-A kinase (AURKA) is a serine/threonine kinase responsible for chromosomal stability during mitosis. Significantly, aberrant expression of AURKA induces breast cancer progression. We hypothesized that aberrant activation of TGF-β and AURKA signaling pathways contributes to chemoresistance in TNBC by promoting EMT and tumor stemness and that dual-targeting of these oncoproteins will enhance chemosensitivity. Methods: RNA-Seq data were analyzed from patient derived xenografts (PDx) established from patients with Stage I-III TNBC who received pre-operative taxane and anthracycline based chemotherapy. Chemoresistance was defined as an RCB score of 1-3, and chemosensitivity was defined as an RCB score of 0. Unique TNBC cell lines developed from brain metastasis PDxs (TNBC M14, TNBC M25) were treated in vitro with 10nM docetaxel (DTX), 50nM LY2157299 (TGF-β inhibitor) and 50nM MLN8237 (AURKA inhibitor). EMT reprogramming was determined by measuring the expression of vimentin, ALDH activity and mammosphere growth. Apoptotic cells following drug treatment were labeled with Red Annexin-V marker and monitored in real time using the IncuCyte instrument. Results: RNA-Seq revealed that there was no baseline difference in expression of AURKA between chemoresistant and chemosensitive TNBC PDxs. However, there was a 2.7-fold increase in AURKA expression in the post-treatment PDx models compared to pre-treatment PDx models. In vitro treatment of the M14 and M25 cell lines with DTX demonstrated no significant increase in apoptotic cells compared to control, whereas treatment with the combination of DTX, LY2157299 and MLN8237 resulted in a two-fold increase in apoptosis compared to treatment with DTX alone (p = 0.0068 M14, p = 0.003 M25). Dual-targeting with LY2157299 and MLN8237 reduced the expression of vimentin and ALDH activity. Conclusions: TGF-β and AURKA play a central role inducing EMT and a stem-cell-like phenotype in TNBC that confers chemoresistance. AURKA is up-regulated after exposure to chemotherapy in chemoresistant TNBC PDx models. LY2157299 and MLN8237 reduce TNBC stemness in M14 and M25 cell lines and enhance DTX chemosensitivity. Dual-targeting of TGF-β and AURKA is a potentially promising approach in chemoresistant TNBC.

BRCA1 Promoter Hypermethylation is Associated with Good Prognosis and Chemosensitivity in Triple-Negative Breast Cancer.

The aberrant hypermethylation of BRCA1 promoter CpG islands induces the decreased expression of BRCA1 (Breast Cancer 1) protein. It can be detected in sporadic breast cancer without BRCA1 pathogenic variants, particularly in triple-negative breast cancers (TNBC). We investigated BRCA1 hypermethylation status (by methylation-specific polymerase chain reaction (MS-PCR) and MassARRAY® assays), and BRCA1 protein expression using immunohistochemistry (IHC), and their clinicopathological significance in 248 chemotherapy-naïve TNBC samples. Fifty-five tumors (22%) exhibited BRCA1 promoter hypermethylation, with a high concordance rate between MS-PCR and MassARRAY® results. Promoter hypermethylation was associated with reduced IHC BRCA1 protein expression (p = 0.005), and expression of Programmed death-ligand 1 protein (PD-L1) by tumor and immune cells (p = 0.03 and 0.011, respectively). A trend was found between promoter hypermethylation and basal marker staining (p = 0.058), and between BRCA1 expression and a basal-like phenotype. In multivariate analysis, relapse-free survival was significantly associated with N stage, adjuvant chemotherapy, and histological subtype. Overall survival was significantly associated with T and N stage, histology, and adjuvant chemotherapy. In addition, patients with tumors harboring BRCA1 promoter hypermethylation derived the most benefit from adjuvant chemotherapy. In conclusion, BRCA1 promoter hypermethylation is associated with TNBC sensitivity to adjuvant chemotherapy, basal-like features and PD-L1 expression. BRCA1 IHC expression is not a good surrogate marker for promoter hypermethylation and is not independently associated with prognosis. Association between promoter hypermethylation and sensitivity to Poly(ADP-ribose) polymerase PARP inhibitors needs to be evaluated in a specific series of patients.

MicroRNA-5195-3p enhances the chemosensitivity of triple-negative breast cancer to paclitaxel by downregulating EIF4A2

BackgroundChemotherapy based on paclitaxel (PTX) is the standard treatment for a range of cancers, including triple-negative breast cancer (TNBC), but the increasing development of resistance has reduced/has negatively impacted its clinical utility. A previous study demonstrated that miR-5195-3p could suppress lung cancer cell growth. This study was designed to investigate whether miR-5195-3p attenuates chemoresistance to PTX by regulating target genes in TNBC cells.MethodsThe study used both PTX-resistant tumor tissues and PTX-resistant TNBC cell lines. The expression of miR-5195-3p was determined using quantitative real-time PCR. Cell viability, cell cycle distribution and apoptosis were analyzed using CCK-8 and flow cytometry assays. The target genes of miR-5195-3p were predicted with bioinformatics analysis and confirmed using the luciferase reporter assay.ResultsMiR-5195-3p expression was lower in PTX-resistant tumor tissues and PTX-resistant TNBC cell lines. Upregulation of miR-5195-3p enhanced the sensitivity of PTX-resistant TNBC cells to PTX treatment. EIF4A2 was confirmed as a potential target of miR-5195-3p. EIF4A2 knockdown imitated the effects of miR-5195-3p on chemosensitivity, while restoration of EIF4A2 rescued them.ConclusionThese data demonstrate that miR-5195-3p might be a potential therapeutic target to reverse chemoresistance in TNBC through its targeting of EIF4A2.

LncRNA AWPPH and miRNA-21 regulates cancer cell proliferation and chemosensitivity in triple-negative breast cancer by interacting with each other.

Long-non-coding RNAs (lncRNA) AWPPH promotes the progression of liver and bladder cancer, indicating its oncogenic role. The current study aimed to explore the involvement of AWPPH in triple-negative breast cancer (TNBC). In the current study, we found that plasma levels of lncRNA AWPPH and microRNA-21 (miRNA-21) were upregulated in patients with TNBC than in healthy controls, and the upregulation of plasma lncRNA AWPPH and miRNA-21 distinguished early-stage patients with TNBC from healthy controls. Plasma levels of lncRNA AWPPH and miRNA-21 were significantly and positively correlated in both patients with TNBC and healthy controls. LncRNA AWPPH and miRNA-21 overexpression led to promoted cancer cells proliferation and improved cancer cell viability under carboplatin treatment, while lncRNA AWPPH small interfering RNA (siRNA) silencing played an opposite role. In addition, miRNA-21 overexpression attenuated the effects of lncRNA AWPPH siRNA silencing on of cancer cell behaviors. LncRNA AWPPH overexpression led to upregulated miRNA-21 in TNBC cells, while miRNA-21 overexpression also led to significantly upregulated lncRNA AWPPH expression. Therefore, lncRNA AWPPH and miRNA-21 may regulate cancer cell proliferation and chemosensitivity in TNBC by interacting with each other.

Prognostic value of IMP3 expression as a determinant of chemosensitivity in triple-negative breast cancer

Triple negative breast cancer (TNBC) has an aggressive phenotype and poor prognosis. Neoadjuvant chemotherapy (NAC) is often used to treat TNBC, but some patients are resistant to NAC. We postulated that a subpopulation of TNBC cells expressing IMP3, an oncofetal protein, could be resistant to NAC, contributing to the poor prognosis. We investigated immunohistochemical expression of IMP3 in 42 TNBC patients who underwent NAC in association with clinical outcomes. The patients were divided into IMP3 positive (+) (n=19) and negative (−) (n=23) groups. High Ki67 positivity was detected in 13 patients of the IMP3+group and 8 cases in the IMP3 – group (p=0.03). While 9 patients in the IMP3 – group (39%) were responders, the majority of the IMP3+patients (84.2%) were non-responders (p=0.01). In a Cox proportional hazard model, IMP3 expression was independently associated with poor NAC response and clinical outcomes (p=0.03 and 0.046, respectively). The IMP3+group showed a tendency toward shorter overall survival compared to the IMP3 – group with marginal significance (p=0.07). These findings suggest that IMP3+tumor cells contributed to the poor clinical outcomes by exerting a chemoresistance to NAC, and that IMP3 expression has prognostic value as a biomarker for chemosensitivity and overall survival in TNBC.

Predictors of Chemosensitivity in Triple Negative Breast Cancer: An Integrated Genomic Analysis.

BackgroundTriple negative breast cancer (TNBC) is a highly heterogeneous and aggressive disease, and although no effective targeted therapies are available to date, about one-third of patients with TNBC achieve pathologic complete response (pCR) from standard-of-care anthracycline/taxane (ACT) chemotherapy. The heterogeneity of these tumors, however, has hindered the discovery of effective biomarkers to identify such patients.Methods and FindingsWe performed whole exome sequencing on 29 TNBC cases from the MD Anderson Cancer Center (MDACC) selected because they had either pCR (n = 18) or extensive residual disease (n = 11) after neoadjuvant chemotherapy, with cases from The Cancer Genome Atlas (TCGA; n = 144) and METABRIC (n = 278) cohorts serving as validation cohorts. Our analysis revealed that mutations in the AR- and FOXA1-regulated networks, in which BRCA1 plays a key role, are associated with significantly higher sensitivity to ACT chemotherapy in the MDACC cohort (pCR rate of 94.1% compared to 16.6% in tumors without mutations in AR/FOXA1 pathway, adjusted p = 0.02) and significantly better survival outcome in the TCGA TNBC cohort (log-rank test, p = 0.05). Combined analysis of DNA sequencing, DNA methylation, and RNA sequencing identified tumors of a distinct BRCA-deficient (BRCA-D) TNBC subtype characterized by low levels of wild-type BRCA1/2 expression. Patients with functionally BRCA-D tumors had significantly better survival with standard-of-care chemotherapy than patients whose tumors were not BRCA-D (log-rank test, p = 0.021), and they had significantly higher mutation burden (p < 0.001) and presented clonal neoantigens that were associated with increased immune cell activity. A transcriptional signature of BRCA-D TNBC tumors was independently validated to be significantly associated with improved survival in the METABRIC dataset (log-rank test, p = 0.009). As a retrospective study, limitations include the small size and potential selection bias in the discovery cohort.ConclusionsThe comprehensive molecular analysis presented in this study directly links BRCA deficiency with increased clonal mutation burden and significantly enhanced chemosensitivity in TNBC and suggests that functional RNA-based BRCA deficiency needs to be further examined in TNBC.

Integration of photothermal therapy and synergistic chemotherapy by a porphyrin self-assembled micelle confers chemosensitivity in triple-negative breast cancer

Triple-negative breast cancer is a malignant cancer type with a high risk of early recurrence and distant metastasis. Unlike other breast cancers, triple-negative breast cancer is lack of targetable receptors and, therefore, patients largely receive systemic chemotherapy. However, inevitable adverse effects and acquired drug resistance severely constrain the therapeutic outcome. Here we tailor-designed a porphyrin-based micelle that was self-assembled from a hybrid amphiphilic polymer comprising polyethylene glycol, poly (d, l-lactide-co-glycolide) and porphyrin. The bilayer micelles can be simultaneously loaded with two chemotherapeutic drugs with synergistic cytotoxicity and distinct physiochemical properties, forming a uniform and spherical nanostructure. The drug-loaded micelles showed a tendency to accumulate in the tumor and can be internalized by tumor cells for drug release in acidic organelles. Under near-infrared laser irradiation, high density of self-quenched porphyrins in the hydrophobic layer absorbed light efficiently and converted into an excited state, leading to the release of sufficient heat for photothermal therapy. The integration of localized photothermal effect and synergistic chemotherapy conferred great chemosensitivity to cancer cells and achieved tumor regression using about 1/10 of traditional drug dosage. As a result, chemotherapy-associated adverse effects were successfully avoided. Our present study established a novel porphyrin-based nanoplatform with photothermal activity and expanded drug loading capacity, providing new opportunities for challenging conventional chemotherapy and fighting against stubborn triple-negative breast cancer.

Filamin A (FLNA) modulates chemosensitivity to docetaxel in triple-negative breast cancer through the MAPK/ERK pathway.

A previous RNA interference (RNAi) screen identified filamin A (FLNA) as a potential biomarker to predict chemosensitivity in triple-negative breast cancer (TNBC). However, its ability to modulate chemosensitivity and the underlying mechanism has not been investigated. Genetic manipulation of FLNA expression has been performed in an immortalized noncancerous human mammary epithelial cell line and four TNBC cell lines to investigate its effect on chemosensitivity. Western blot analysis was performed to identify the potential signaling pathway involved. Xenograft mouse model was used to examine the in vivo role of FLNA in modulating chemosensitivity. Overexpression of FLNA conferred chemoresistance to docetaxel in noncancerous human mammary epithelial cells. Knockdown of FLNA sensitized four TNBC cell lines, MDA-MB-231, HCC38, Htb126, and HCC1937 to docetaxel which was reversed by reconstituted FLNA expression. Decreased FLNA expression correlated with decreased activation of ERK. Constitutive activation of ERK2 reversed siFLNA-induced chemosensitization. Inhibition of MEK1 recapitulates the effect of FLNA knockdown. MDA-MB-231 xenograft with FLNA knockdown showed enhanced response to docetaxel compared with control xenograft with increased apoptosis. FLNA can function as a modulator of chemosensitivity to docetaxel in TNBC cells through regulation of the MAPK/ERK pathway both in vitro and in vivo. FLNA may serve as a novel therapeutic target for improvement of chemotherapy efficacy in TNBC.

P2-3-1 - Tle3 is a Useful Surrogate Marker for Predicting Eribulin Chemo-Sensitivity in Triple-Negative Breast Cancer

Background: Eribulin mesylate (eribulin) is a microtubule dynamics inhibitor having an action mechanism that differs from taxane and vinca alkaloid. Eribulin does not have cross resistance due to an action mechanism that differs from other taxane drugs. Moreover, because it was effective against TNBC upon sub-analysis at phase III clinical trial 301, it is expected to become the key drug for chemotherapy against TNBC in the future. In this study, we investigated predictive factors regarding the therapeutic effect in eribulin chemotherapy using factors such as TLE3, beta-tubulin class III, GSTP1, etc. previously reported as being predictive factors of the therapeutic effect of taxane drugs.Methods: The subjects were 52 inoperable or metastasis / recurrent breast cancer cases that underwent chemotherapy using eribulin. The clinical benefit rate (CBR) was calculated regarding the efficacy thereof. Morphologies such as tissue-type, nucleus grade, etc. were compared by hematoxylin and eosin staining and the expression of ER, PR, HER2, Ki67, beta-tubulin class III, GSTP1, and TLE3 was compared by immunostaining regarding a needle biopsy specimen infiltrate prior to treatment.Results: The clinical effects were CBR 46.2 per cent. According to the intrinsic subtype classification: Luminal A: 16 cases: Luminal B: 12 cases: Luminal HER2: 2 cases: HER2 enriched: 3 cases: and TNBC: 19 cases. When the clinicopathological background and expression of each factor were investigated, TNBC was observed with significantly higher expression of TLE3 compared to non-TNBC; however, no significant difference was observed regarding other factors. Further, breast cancer patients with TLE3 expression had significantly higher CBR. Meanwhile, no significant difference was observed in beta-tubulin class III and GSTP1 expression.Conclusions: Our findings therefore suggest that TLE3 may be useful as a marker for predicting the therapeutic effect in eribulin chemotherapy for TNBC.

A Targeted RNAi Screen of the Breast Cancer Genome Identifies KIF14 and TLN1 as Genes That Modulate Docetaxel Chemosensitivity in Triple-Negative Breast Cancer

To identify biomarkers within the breast cancer genome that may predict chemosensitivity in breast cancer. We conducted an RNA interference (RNAi) screen within the breast cancer genome for genes whose loss-of-function enhanced docetaxel chemosensitivity in an estrogen receptor-negative, progesterone receptor-negative, and Her2-negative (ER-, PR-, and Her2-, respectively) breast cancer cell line, MDA-MB-231. Top candidates were tested for their ability to modulate chemosensitivity in 8 breast cancer cell lines and to show in vivo chemosensitivity in a mouse xenograft model. From ranking chemosensitivity of 328 short hairpin RNA (shRNA) MDA-MB-231 cell lines (targeting 133 genes with known somatic mutations in breast cancer), we focused on the top two genes, kinesin family member 14 (KIF14) and talin 1 (TLN1). KIF14 and TLN1 loss-of-function significantly enhanced chemosensitivity in four triple-negative breast cancer (TNBC) cell lines (MDA-MB-231, HCC38, HCC1937, and Hs478T) but not in three hormone receptor-positive cell lines (MCF7, T47D, and HCC1428) or normal human mammary epithelial cells (HMEC). Decreased expression of KIF14, but not TLN1, also enhanced docetaxel sensitivity in a Her2-amplified breast cancer cell line, SUM190PT. Higher KIF14 and TLN1 expressions are found in TNBCs compared with the other clinical subtypes. Mammary fat pad xenografts of KIF14- and TLN1-deficient MDA-MB-231 cells revealed reduced tumor mass compared with control MDA-MB-231 cells after chemotherapy. KIF14 expression is also prognostic of relapse-free and overall survival in representative breast cancer expression arrays. KIF14 and TLN1 are modulators of response to docetaxel and potential therapeutic targets in TNBC.

E-cadherin and Ki67 are Predictive Markers for Chemosensitivity in Triple-negative Breast Cancer

E-cadherin and Ki67 are Predictive Markers for Chemosensitivity in Triple-negative Breast Cancer

Abstract 2708: E-cadherin expression might be a predictive marker for chemosensitivity in triple-negative breast cancer

Abstract Introduction: Triple-negative breast cancer (TNBC), a subtype of breast tumor with ER negative, PR negative, and HER2 negative, shows a poor prognosis because of a frequent recurrence. Chemotherapy is important for the treatment of recurrent TNBC, however no reliable parameter has been identified for chemo-sensitivity in TNBC. Although E-cadherin is one of markers for chemo-sensitivity in several types of carcinomas, not much of the correlation between E-cadherin expression and chemo-sensitivity is known in TNBC. The aim of this study was to evaluate the significance of E-cadherin in TNBC. Material and Methods: The subjects of this study were 574 patients with primary infiltrating breast ductal cancer. Adjuvant therapy was performed according to the guidelines of breast cancer by NCCN. ER and PR status were assessed by immunohistochemistry. HER2 status was assessed by either immunohistochemistry or fluorescent in situ hybridization. E-cadherin expression was immunohistochemically analyzed by ABC method. E-cadherin expression was semi-quantitatively analyzed according to the percentage of cells showing membrane positivity: 0-10%; 0, 10-30%; 1+, 30-70%; 2+, &amp;gt;70%; 3+. E-cadherin expression was considered positive when scores were ≥2+. Results: Among the 574 breast cancer cases, 123 (21.4%) revealed a triple-negative phenotype. Reduced levels of E-cadherin were observed in 238 (41.5%) of the 574 breast cancer cases. The cases with E-cadherin loss was frequent (90 of 123 cases) in TNBC. Eighty-nine cases of 123 TNBC cases were performed chemotherapy. In 89 TNBC cases with chemotherapy, the prognosis of E-cadherin-negative patients is significantly poor (p&amp;lt;0.01), in comparison with that of E-cadherin-positive patients, while a multiple analysis demonstrated that reduction of E-cadherin expression was not an independent prognostic factor. In contrast, no significant difference of prognosis between E-cadherin positive patients and negative patients was found in 34 TNBC cases without chemotherapy. Conclusion: E-cadherin might be a useful predictive marker for chemo-sensitivity in TNBC. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 2708.