MicroRNA-497-5p Functions as a Modulator of Apoptosis by Regulating Metadherin in Ovarian Cancer

Abstract

Ovarian cancer (OC) has a high mortality rate among women worldwide. However, even with the advances in detection and therapeutics, the number of cases is increasing worldwide. Increasingly, microRNAs (miRNAs), including miR-497-5p, have been implicated in the progression of many cancers, but the role of miR-497-5p in OC remains unknown. The purpose of this study was to investigate the underlying molecular mechanism of miR-497-5p in OC. Herein, we find that miR-497-5p is down-regulated in OC tissues, and overexpression of miR-497-5p enhances apoptosis in OC cells. The increased apoptosis was correlated with enhanced expression of apoptosis-related proteins. MiR-497-5p directly bound the 3'-untranslated region of metadherin (MTDH), leading to the reduction of MTDH in mRNA and protein levels. Moreover, MTDH knockout promoted the apoptosis of OC cells. Taken together, we conclude that miR-497-5p contributes to cell apoptosis in OC by regulating MTDH.

Keywords: MTDH; apoptosis; miR-497-5p; ovarian cancer.

Figure 1.

miR-497-5p expression was down-regulated in OC tissues. miR-497-5p expression was detected by qRT-PCR in 12 paired OC tissues and paired non-tumorous tissues. *p < 0.05 vs. non-tumorous tissues.

Figure 2.

Apoptosis effects of miR-497-5p overexpression in SKOV-3 and TOV-112D cells. (A) Relative levels of miR-497-5p in SKOV-3 and TOV-112D cells were determined by qRT-PCR after miR-497-5p overexpression. (B, C) miR-497-5p overexpression significantly increased apoptosis in SKOV-3 and TOV-112D cells. (D, E) Western blot showing increased apoptotic proteins (cleaved PARP and caspase-3) in both in SKOV-3 and TOV-112D cells overexpressing miR-497-5p. *p < 0.05 vs. untransfected cells; ^p < 0.05 vs. miR-NC; n = 3.

Figure 3.

MTDH expression was up-regulated in OC tissues. MTDH mRNA levels were detected by qRT-PCR in 12 paired OC tissues and paired non-tumorous tissues. *p < 0.05 vs. non-tumorous tissues.

Figure 4.

MTDH is a target of miR-497-5p. (A) 3’-UTR luciferase reporter assays. SKOV-3 and TOV-112D cells were co-transfected with miR-497-5p or miR-NC and MTDH 3’-UTR luciferase reporter construct. Firefly luciferase activity was normalized to Renilla luciferase activity. (B) Relative level of MTDH mRNA in SKOV-3 and TOV-112D cells was determined by qRT-PCR after miR-497-5p overexpression. (C) MTDH protein expression in SKOV-3 and TOV-112D cells was determined by western blotting after miR-497-5p overexpression. *p < 0.05 vs. untransfected cells; ^p < 0.05 vs. miR-NC; n = 3.

Figure 5.

Apoptosis effects of MTDH knockout in SKOV-3 and TOV-112D cells. (A) Relative levels of MTDH mRNA in SKOV-3 and TOV-112D cells were determined by qRT-PCR after MTDH knockout. (B) MTDH protein expression in SKOV-3 and TOV-112D cells was determined by western blotting after MTDH knockout. (C) (D) MTDH knockout overexpression significantly increased apoptosis in SKOV-3 and TOV-112D cells. (E) Western blot showing increased apoptotic proteins (cleaved PARP and caspase-3) in both in SKOV-3 and TOV-112D cells after knockout. *p < 0.05 vs. untransfected cells; ^p < 0.05 vs. miR-NC; n = 3.