Updates in cancer research: insights from the AACR 100th Annual Meeting

microRNA-199a is able to reverse cisplatin resistance in human ovarian cancer cells through the inhibition of mammalian target of rapamycin

microRNAs (miRNAs/miRs) may have a crucial function in tumor metastasis through the regulation of a plethora of signaling pathways. Increasing evidence has shown that miR-199a is important in regulating the tumor metastasis of ovarian cancer, although the precise biological function of miR-199a is unclear at present. In the current study, it was observed that the expression levels of miR-199a were higher in OV2008 cells compared with C13* cells. However, lower levels of mammalian target of rapamycin (mTOR) protein were detected by western blotting in the OV2008 cells compared with the C13* cells. The miR-199a levels were increased in the C13* cells using miR-199a mimics and the mTOR levels were observed to decrease. This may have resulted in a reversal of cisplatin resistance in the C13* cells. To test this hypothesis, the Renilla luciferase reporter gene system was used to analyze the mTOR levels. The results indicated that the expression levels of mTOR were significantly blocked by the increased miR-199a levels. When the miR-199a inhibitor was applied to decrease the miR-199a levels, it was observed that the mTOR expression levels were increased, while cisplatin-induced apoptosis was decreased in the OV2008 cells. The study concludes that miR-199a is able to reverse cisplatin resistance in human ovarian cancer cells through the inhibition of mTOR and that mTOR may be the target of miR-199a during this process.

MicroRNAs: potential biomarkers for cancer diagnosis, prognosis and targets for therapy

MicroRNAs have a revolutionary impact on cancer research over recent years. They emerge as important players in tumorigenesis, leading to a paradigm shift in oncology. The widespread and comprehensive use of microRNA microarrays has enabled the identification of a number of microRNAs as potential biomarkers for cancer. It is encouraging to report that microRNAs have remarkable stability in both formalin-fixed tissue and blood. Many microRNAs have been identified to act as oncogenes, tumor suppressors, or even modulators of cancer stem cells and metastasis. Some studies not only reported the identified microRNA biomarkers, but also deciphered their target genes and the underlying mechanisms. The rapid discovery of many microRNA targets and their relevant pathways has contributed to the development of microRNA-based therapeutics, but the developing progress of antisense or siRNA drugs has been hampered by stability, specificity and delivery problems. This review summarizes the most significant and latest findings of original researches on microRNAs involvement in cancer, focusing on the potential of cancer-related microRNAs as biomarkers for diagnosis, prognosis and targets for therapy.