MicroRNAs (miRNAs) are small non-coding RNAs with a length of about 19–25 nt, which can regulate various target genes and are thus involved in the regulation of a variety of biological and pathological processes, including the formation and development of cancer. Drug resistance in cancer chemotherapy is one of the main obstacles to curing this malignant disease. Statistical data indicate that over 90% of the mortality of patients with cancer is related to drug resistance. Drug resistance of cancer chemotherapy can be caused by many mechanisms, such as decreased antitumor drug uptake, modified drug targets, altered cell cycle checkpoints, or increased DNA damage repair, among others. In recent years, many studies have shown that miRNAs are involved in the drug resistance of tumor cells by targeting drug-resistance-related genes or influencing genes related to cell proliferation, cell cycle, and apoptosis. A single miRNA often targets a number of genes, and its regulatory effect is tissue-specific. In this review, we emphasize the miRNAs that are involved in the regulation of drug resistance among different cancers and probe the mechanisms of the deregulated expression of miRNAs. The molecular targets of miRNAs and their underlying signaling pathways are also explored comprehensively. A holistic understanding of the functions of miRNAs in drug resistance will help us develop better strategies to regulate them efficiently and will finally pave the way toward better translation of miRNAs into clinics, developing them into a promising approach in cancer therapy.

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The role and mechanisms of action of microRNAs in cancer drug resistance.

Motivation Molecule-based prediction of drug response is one major task of precision oncology. Recently, large-scale cancer genomic studies, such as The Cancer Genome Atlas (TCGA), provide the opportunity to evaluate the predictive utility of molecular data for clinical drug responses in multiple cancer types. Results Here, we first curated the drug treatment information from TCGA. Four chemotherapeutic drugs had more than 180 clinical response records. Then, we developed a computational framework to evaluate the molecule based predictions of clinical responses of the four drugs and to identify the corresponding molecular signatures. Results show that mRNA or miRNA expressions can predict drug responses significantly better than random classifiers in specific cancer types. A few signature genes are involved in drug response related pathways, such as DDB1 in DNA repair pathway and DLL4 in Notch signaling pathway. Finally, we applied the framework to predict responses across multiple cancer types and found that the prediction performances get improved for cisplatin based on miRNA expressions. Integrative analysis of clinical drug response data and molecular data offers opportunities for discovering predictive markers in cancer. This study provides a starting point to objectively evaluate the molecule-based predictions of clinical drug responses. Contact jgu@tsinghua.edu.cn Supplementary information Supplementary data are available at Bioinformatics online.

Evaluating the molecule-based prediction of clinical drug responses in cancer

Epithelial-to-Mesenchymal transition (EMT) is a physiological process that is vital throughout the human lifespan. In addition to contributing to the development of various tissues within the growing embryo, EMT is also responsible for wound healing and tissue regeneration later in adulthood. In this review, we highlight the importance of EMT in the development and normal functioning of the female reproductive organs (the ovaries and the uterus) and describe how dysregulation of EMT can lead to pathological conditions such as endometriosis, adenomyosis and carcinogenesis. We also summarize the current literature relating to EMT in the context of ovarian and endometrial carcinomas, with a particular focus on how molecular mechanisms and the tumor microenvironment can govern cancer cell plasticity, therapy resistance and metastasis.

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Epithelial-to-Mesenchymal Transition in the Female Reproductive Tract: From Normal Functioning to Disease Pathology

miRNA profile in ovarian cancer.

MicroRNAs in gynecological cancers: Small molecules with big implications

Epithelial ovarian cancer (EOC) is the leading cause of death from gynecologic malignancies. Platinum-based chemotherapy is the first-line treatment for the advanced ovarian cancer, but resistance to cisplatin remains a major obstacle to successful treatment. MicroRNAs (miRNAs) are a class of non-coding RNAs that play important roles in disease processes, including the development of drug resistance. In this study, we found miR-449a were significantly downregulated in the cisplatin-resistant ovarian cell lines SKOV3/DDP and A2780/DDP, compared with their sensitive parent line SKOV3 and A2780, respectively. The overexpression of miR-449a increased cisplatin sensitivity of SKOV3/DDP and A2780/DDP cells by inhibiting proliferation and promoting apoptosis. The luciferase assay confirmed that miR-449a functioned through suppressing NOTCH1 directly. Concordantly, BALB/c nude mice that were injected intraperitoneally with SKOV3/DDP cells transfected with miR-449a mimics exhibited enhanced cisplatin sensitivity in vivo. Taken together, these results suggest that the ectopic expression of miR-449a may be a promising therapeutic strategy for the management of cisplatin resistance in ovarian cancer.

Kaifeng Zhang

Papers

MicroRNA-449a reduces cell survival and enhances cisplatin-induced cytotoxicity via downregulation of NOTCH1 in ovarian cancer cells