Comprehensive transcriptome analysis identifies novel molecular subtypes and subtype-specific RNAs of triple-negative breast cancer

Current Status of Long Non-Coding RNAs in Human Breast Cancer

Breast cancer represents a major health burden in Europe and North America, as recently published data report breast cancer as the second leading cause of cancer related death in women worldwide. Breast cancer is regarded as a highly heterogeneous disease in terms of clinical course and biological behavior and can be divided into several molecular subtypes, with different prognosis and treatment responses. The discovery of numerous non-coding RNAs has dramatically changed our understanding of cell biology, especially the pathophysiology of cancer. Long non-coding RNAs (lncRNAs) are non-protein-coding transcripts >200 nucleotides in length. Several studies have demonstrated their role as key regulators of gene expression, cell biology and carcinogenesis. Deregulated expression levels of lncRNAs have been observed in various types of cancers including breast cancer. lncRNAs are involved in cancer initiation, progression, and metastases. In this review, we summarize the recent literature to highlight the current status of this class of long non-coding lncRNAs in breast cancer.

Co-expression networks revealed potential core lncRNAs in the triple-negative breast cancer

Triple-negative breast cancer (TNBC) is an aggressive type of breast cancer with unfavorable outcome. It is urgent to explore novel biomarkers and potential therapeutic targets in this malignancy. Increasing knowledge of long noncoding RNAs (lncRNAs) significantly deepens our understanding of cancer biology. Here, we sequenced eight paired TNBC tumor tissues and non-cancerous tissues, and validated significantly differentially expressed lncRNAs. Gene ontology (GO) and pathway analysis were used to investigate the function of differentially expressed mRNAs. Further, potential core lncRNAs in TNBC were identified by co-expression networks. Kaplan-Meier analysis also indicated that breast cancer patients with lower expression level of rhabdomyosarcoma 2 associated transcript (RMST), one of the potential core lncRNAs, had worse overall survival. To the best of our knowledge, it was the first report that RMST was involved in breast cancer. Our research provided a rich resource to the research community for further investigating lncRNAs functions and identifying lncRNAs with diagnostic and therapeutic potentials in TNBC.

Birinapant (TL32711) Improves Responses to GEM/AZD7762 Combination Therapy in Triple-negative Breast Cancer Cell Lines

BACKGROUND

Triple-negative breast cancer (TNBC) is an aggressive form of breast cancer currently lacking targeted therapies. Our previous work demonstrated a therapeutic synergism with gemcitabine (GEM) and the CHK1 inhibitor (AZD7762) combination treatment in a TNBC cell line. We hypothesized that the response to this combination therapy would differ among heterogeneous TNBC patients and that addition of a SMAC mimetic (TL32711) could improve efficacy.

MATERIALS AND METHODS

Therapeutic responses to GEM, GEM/AZD7762, and GEM/AZD7762/TL32711 combinations were investigated by XTT assays and western blotting of cell cycle and apoptosis-related proteins in ten TNBC cell lines.

RESULTS

TNBC cell lines harboring low levels of endogenous CHK1, cIAP1 and cIAP2 were responsive to GEM alone, whereas cell lines demonstrating a minimal increase in phospho-S345 CHK1 after treatment were responsive to GEM/AZD7762 or GEM/AZD7762/TL32711 combination.

CONCLUSION

The response of TNBC cells to particular therapies varies and will require development of predictive biomarkers.