Effects of miR-455 on PIK3R1 gene expression regulation and kidney cancer cell functions.

OBJECTIVE: Migration and proliferation of kidney cancer cells are critical factors affecting effective treatment. Abnormal gene expression exists during cancer pathogenesis. The study showed certain effects of PIK3R1 gene on migration and proliferation of kidney cancer cells, although a few studies have been performed regulatory mechanism of microRNA on PIK3R1 gene. Previous sequencing of PIK3R1 gene found the existence of mir-455 binding site. This study confirmed the regulation of PIK3R1 gene expression in kidney cancer cells of mir-455 by in vitro assay, and analyzed its effects on migration or proliferation of kidney cancer cells.

MATERIALS AND METHODS: mir-455 agonist and inhibitor sequences were designed and synthesized to transfect kidney cancer cell line CAKI-1, which were further divided into agonist, inhibitor, and control group. qRT-PCR was used to test expression of mir-455 and PIK3R1 at 12 h, 24 h and 48 h after transfection. PIK3R1 protein expression was measured by Western blot. MTT and cell scratch assay were employed to measure cell proliferation and migration potency.

RESULTS: 12 h after transfection with mir-455, no significant difference of the level of PIK3R1was found among the three groups (p>0.05). However, at 24 h and 48 h post-transfection, PIK3R1 expression in agonist group was significantly elevated, along with weakened cell proliferation or migration potency (p<0.05 with significant between-group comparison). By contrast, the level of PIK3R1 was statistically decreased in inhibitor group, in which cell proliferation and migration were enhanced (p<0.05).

CONCLUSIONS: In kidney carcinoma cell CAKI-1, mir-455 expression regulation can positively alter PIK3R1 gene expression. Over-expression of PIK3Ra gene could reduce the proliferation or migration potency of CAKI-1 cells.