MiR-335-5p Inhibits Cell Proliferation, Migration and Invasion in Colorectal Cancer through Downregulating LDHB

Colorectal cancer (CRC) is a common malignancy which has a high mortality rate around the world. The advancement of new therapeutic strategies is crucial for the efficient treatment of CRC. Many miRNAs play a central role in the progression of cancer cells. There are still few studies on miR-335-5p and CRC. In this study, the potential of miR-335-5p in CRC development and progression was explored.

The expression level of miR-335-5p in CRC cell lines and tissues was detected by quantitative real-time polymerase chain reaction (qRT-PCR) assay. Cell counting kit-8 (CCK8) assay and colony formation assay were applied for evaluating the ability of cell proliferation. Wound healing assay and Transwell assay were applied for detecting cell migration and invasion ability. Moreover, dual luciferase reporter assay was performed to validate if lactic dehydrogenase B (LDHB) is a downstream target of miR-335-5p. Western blotting was used to estimate the expression of protein.

The expression of miR-335-5p was significantly low in CRC tissues and cells. To investigate the function of miR-335-5p in CRC, two CRC cell lines (HCT-116 and SW620) were selected for further experiments. After transfection with mimics and inhibitor to up-regulate or down-regulate miR-335-5p, it was found that overexpression of miR-335-5p obviously decreased cell proliferation and inhibited migration ability and invasion, while the knockdown of miR-335-5p could obtain the opposite results. Then it was validated in dual luciferase reporter assay that LDHB could be a potential directive target gene of miR-335-5p. Moreover, the rescue assay confirmed that miR-335-5p executed its function as a tumor suppressor gene through targeting LDHB in CRC.

To sum up, the present study demonstrated that miR-335-5p regulates cell proliferation, migration as well as invasion of CRC cells through down-regulating LDHB, and demonstrated that miR-335-5p/LDHB axis may be an underlying therapeutic strategy in CRC.