Mechanism of the enhancing effects of miR-93 on resistance of breast cancer MCF-7 cells to adriamycin

Radiation prevents tumor progression by inhibiting the miR‑93‑5p/EphA4/NF‑κB pathway in triple‑negative breast cancer

Breast cancer (BC) is the most common type of cancer in women. Triple‑negative BC (TNBC) constitutes 10‑15% of all BC cases and is associated with a poor prognosis. It has previously been reported that microRNA (miR)‑93‑5p is dysregulated in plasma exosomes from patients with BC and that miR‑93‑5p improves radiosensitivity in BC cells. The present study identified EphA4 as a potential target gene of miR‑93‑5p and investigated the pathway related to miR‑93‑5p in TNBC. Cell transfection and nude mouse experiments were performed to verify the role of the miR‑93‑5p/EphA4/NF‑κB pathway. Moreover, miR‑93‑5p, EphA4 and NF‑κB were detected in clinical patients. The results revealed that EphA4 and NF‑κB were downregulated in the miR‑93‑5p overexpression group. By contrast, EphA4 and NF‑κB expression levels were not significantly altered in the miR‑93‑5p overexpression + radiation group compared with those in the radiation group. Furthermore, overexpression of miR‑93‑5p with concomitant radiation therapy significantly decreased the growth of TNBC tumors in vivo. In conclusion, the present study revealed that miR‑93‑5p targeted EphA4 in TNBC through the NF‑κB pathway. However, radiation therapy prevented tumor progression by inhibiting the miR‑93‑5p/EphA4/NF‑κB pathway. Therefore, it would be interesting to elucidate the role of miR‑93‑5p in clinical research.

MiR-93 suppresses tumorigenesis and enhances chemosensitivity of breast cancer via dual targeting E2F1 and CCND1

Chemoresistance of tumors often leads to treatment failure in clinical practice, which underscores pivotal needs to uncover novel therapeutic strategies. Accumulating evidences show that microRNAs (miRNAs) are widely involved in carcinogenesis, but their function on chemoresistance remains largely unexplored. In this study, we found that miR-93-5p (miR-93) significantly inhibited cell proliferation, induced G1/S cell cycle arrest and increased chemosensitivity to paclitaxel (PTX) in vitro and in vivo. Moreover, two well-established oncogenes, E2F1 and CCND1, were identified as dual targets of miR-93. Knockdown of E2F1 and CCND1 reduced cell proliferation and PTX-sensitivity, whereas overexpression of them had the opposite effect. More importantly, overexpression of E2F1 and CCND1 antagonized miR-93-mediated cell cycle arrest and apoptosis. Further mechanistic study revealed that miR-93 exhibited its inhibitory role by directly targeting E2F1 and CCND1 to inactivate pRB/E2F1 pathway and AKT phosphorylation. Taken together, our findings suggested that miR-93 greatly improved chemosensitivity and potentially served as a novel therapeutic target for breast cancer treatment.

Flaming the fight against cancer cells: the role of microRNA-93

There have been attempts to develop novel anti-tumor drugs in cancer therapy. Although satisfying results have been observed at a consequence of application of chemotherapeutic agents, the cancer cells are capable of making resistance into these agents. This has forced scientists into genetic manipulation as genetic alterations are responsible for generation of a high number of cancer cells. MicroRNAs (miRs) are endogenous, short non-coding RNAs that affect target genes at the post-transcriptional level. Increasing evidence reveals the potential role of miRs in regulation of biological processes including angiogenesis, metabolism, cell proliferation, cell division, and cell differentiation. Abnormal expression of miRs is associated with development of a number of pathologic events, particularly cancer. MiR-93 plays a significant role in both physiological and pathological mechanisms. At the present review, we show how this miR dually affects the proliferation and invasion of cancer cells. Besides, we elucidate the oncogenesis or oncosuppressor function of miR-93.

miRNA expression changes during the course of neoadjuvant bevacizumab and chemotherapy treatment in breast cancer

One of the hallmarks of cancer is sustained angiogenesis. Favorable results have been reported in some breast cancer (BC) patients receiving antiangiogenic therapy with bevacizumab (Bev) in combination with chemotherapy, and further knowledge on how Bev can be optimally combined with conventional treatment to increase efficacy is strongly needed. In this randomized, neoadjuvant phase II clinical trial, 132 patients with HER2-negative, nonmetastatic BC were treated with Bev in combination with sequential chemotherapy. Biopsies were sampled before treatment, after 12 weeks with anthracycline and after taxane therapy at week 25. MicroRNA (miRNA) expression profiling was performed on biopsies from each time point. Altogether, 241 biopsies were analyzed with the aim of identifying miRNA-based biomarkers of response to therapy. Results from the miRNA analyses were reported for the ER-positive cohort, which were previously demonstrated to benefit from antiangiogenic therapy in this study. For both treatment arms of this cohort, significantly different expression was observed for 217 miRNAs between objective responding and nonresponding patients before treatment initiation. These miRNAs have been linked to regulation of epithelial-mesenchymal transition, metastasis, and tumor growth, among other processes. Bev in combination with chemotherapy resulted in similar miRNA changes to chemotherapy alone. However, the deregulation of miRNA expression occurred earlier in the Bev arm. In both arms, tumor suppressor miRNAs were found upregulated after treatment, while oncogenic miRNAs were downregulated in the Bev arm. Patients responding to Bev showed a strong correlation between deregulated miRNAs and decreased proliferation score during the course of treatment, with downregulation of miR-4465 as the strongest indicator of reduced proliferation. Integrative analyses at miRNA-, gene-, and protein expression further indicated a longitudinal decrease in proliferation. Altogether, the results indicate that proliferation might represent a predictive factor for increased Bev sensitivity, which may aid in the identification of patients who could potentially benefit from Bev.