Project description:PARP inhibitor and platinum based drugs such as cisplatin are promising therapies for triple negative breast cancer and exploit the deficiencies in BRCA1 or BRCA2, or homologous recombination repair defects. However, PARP inhibitor resistance is proven to be a major clinical problem. Acquired PARP inhibitor resistance has been linked with co-resistance to platinum-based drugs. To determine how acquired olaparib resistance affects cisplatin response and whether this is influenced by their BRCA1 status, we performed RNAseq transcriptome analysis of isogenic triple negative breast cancer models of olaparib resistance with normal and mutant BRCA1.
Project description:We report transcriptome profiling (RNA-seq) for SMARA4 knock-out to elucidate the association with cisplatin-resistance and SMARCA4 loss-of-function using triple negative breast cancer cell lines.
Project description:Fra-1 (FOSL1) is overexpressed in triple-negative breast cancer (TNBC). Fra-1 is a member of the activator protein 1 (AP-1) transcription factor complex, which plays crucial roles in tumor progression and treatment resistance. We have previously identified 118 proteins that interact with endogenous chromatin-bound Fra-1 in TNBC cells in a large screen, and these included PARP1(Poly (ADP-ribose) polymerase 1). PARP1 inhibitor olaparib is currently in clinical use for treatment of BRCA-mutated TNBC breast cancer. Here, we demonstrate that this interaction impacts the efficacy of olaparib treatment. We corroborate that PARP1 interacts with Fra-1, and we show that PARP1 downregulates Fra-1 and consequently reduces AP-1 transcriptional activity. Inhibition of PARP1, on the other hand, increases Fra-1 levels and enhances its transcriptional activity, which in turn can increase treatment resistance. However, by inhibiting Fra-1, we found that TNBC cells became sensitized to olaparib treatment. We compared Fra-1 chromatin binding sites with the Fra-1 and PARP1 regulated transcriptomes, and found that a large fraction of PARP1-regulated genes was dependent on Fra-1. We further show that PARP1 protein levels significantly correlate with Fra-1 in clinical breast cancer tumors, and we identify that high PARP1 expression is indicative of a poor clinical outcome in breast cancer patients overall, but not in basal-like tumors. In conclusion, by exploring the functionality of the Fra-1 and PARP1 interaction, we propose that targeting Fra-1 could serve as a therapeutic approach to improve olaparib treatment outcome for TNBC patients.
Project description:Breast cancers lacking receptors for estrogen, progesterone or HER2 on their cell surface are called triple-negative breast cancers (TNBCs). TNBCs account for ~15-20% of all invasive breast cancers and do not benefit from anti-hormonal or anti-HER2 treatments. Although patients with TNBC can initially respond to chemotherapy, they do have worse overall prognosis compared to other breast cancer subtypes. Unfortunately, TNBCs lack clear targetable ‘driver’ oncogenes. Thus, there is an unmet need for strategies to improve the therapeutic options for these patients. We used microarrays to assess differences in gene expression in triple-negative breast cancer cells in response to the platinum-based chemotherapeutic agent cisplatin. The purpose was to find drug induced changes in gene expression level that could differentiate cisplatin sensitive from cisplatin resistant TNBC cell lines.
Project description:Evidence suggests that BRCA1 mutation associated tumors have increased sensitivity to DNA damaging agents like cisplatin. Sporadic triple negative breast cancers (TNBC) have many phenotypic similarities to BRCA1 tumors and may have a similar sensitivity to cisplatin. We tested the efficacy of cisplatin monotherapy in 28 TNBC patients in a single arm neoadjuvant trial with outcome measured by pathologic treatment response quantified using the Miller-Payne scale. We used microarrays gene expression profiles to determine tumor subtype of each trial tumor sample and to test various expression signatures for association with pathologic response to cisplatin.
Project description:Evidence suggests that BRCA1 mutation associated tumors have increased sensitivity to DNA damaging agents like cisplatin. Sporadic triple negative breast cancers (TNBC) have many phenotypic similarities to BRCA1 tumors and may have a similar sensitivity to cisplatin. We tested the efficacy of cisplatin monotherapy in 28 TNBC patients in a single arm neoadjuvant trial with outcome measured by pathologic treatment response quantified using the Miller-Payne scale. We used microarrays gene expression profiles to determine tumor subtype of each trial tumor sample and to test various expression signatures for association with pathologic response to cisplatin. Pretreatment tumor samples from the clinical trial (N=24 with adequate tissue) were used for RNA extraction, linear amplification, biotin labeling and hybridization to Affymetrix U133 plus 2.0 arrays. A reference set of 51 primary breast tumors representing all subtypes of breast cancer were processed in a similar manner to include linear amplification, and hybridized to Affymetrix arrays.
Project description:TAB182 participates in DNA damage repair and radio-/chemosensitivity regulation in various tumors, but its role in tumorigenesis and therapeutic resistance in breast cancer remains unclear. In the current paper, we observed that triple-negative Breast Cancer (TNBC), a highly aggressive type of breast cancer, exhibits a lower expression of TAB182. TAB182 knockdown stimulates the proliferation, migration, and invasion of TNBC cells. Our study first obtained RNA-seq data to explore the cellular functions mediated by TAB182 at the genome level in TNBC cells. A transcriptome analysis and in vitro experiments enabled us to identify that TAB182 downregulation drives the enhanced properties of cancer stem-like cells (CSCs) in TNBC cells. Furthermore, TAB182 deletion contributes to the resistance of cells to olaparib or cisplatin, which can be rescued by silencing GLI2, a gene downstream of cancer stemness-related signaling pathways. Our results reveal a novel function of TAB182 as a potential negative regulator of cancer stem-like properties and drug sensitivity in TNBC cells, suggesting that TAB182 may be a tumor suppressor gene and is associated with increased therapeutic benefits for TNBC patients.