MicroRNA-335 Inhibits the Growth, Chemo-Sensitivity, and Metastasis of Human Breast Cancer Cells by Targeting MAP3K2

J BUON. Mar-Apr 2020;25(2):666-674.


Purpose: Molecular mechanism of breast cancer (BC) is relatively unknown and its metastasis is highly complicated. In this context, the characterization of miR-335 was undertaken in (BC).

Methods: qRT-PCR was carried out to analyze the expression of miR-335 in three different (BC) cell lines and normal epithelial breast cell line. Cell proliferation, survival, and viability of (BC) cells were estimated by MTT assay, clonogenic colony forming, and DAPI staining methods, respectively. Target identification of miR-335 was made through online bioinformatics and validated through the correlation of gene expression, western blotting experiments, and luciferase reporter assay. Cell migration and invasion were analyzed through transwell chamber assay.

Results: miR-335 is downregulated in (BC) cells and has inhibitory effect on cell growth, which was manifested as decline in cell survival and loss of cancer cell viability . Further, the chemo-sensitivity of (BC) cells to paclitaxel and doxorubicin was seen to be enhanced under miR-335 overexpression. miR-335 also inhibited the migration and invasion of cancer cells. MAP3K2 was shown to be the target gene of miR-335 and the silencing of MAP3K2 was seen to mimic the growth inhibitory effect of miR-335. The overexpression of MAP3K2 reversed the growth inhibition in miR-335 mimics-transfected BC cells.

Conclusion: miR-335 has growth inhibitory effect against BC and negatively regulates the cell migration and invasion along with enhancement of chemo-sensitivity of cancer cells.