MicroRNA-211 suppresses prostate cancer proliferation by targeting SPARC

Abstract

Dysregulation of microRNAs (miRNAs/miRs) is frequently associated with cancer progression. Altered expression of miR-211 has been observed in various types of human cancer; however, its expression and role in prostate cancer (PCa) remains unknown. In the present study, the expression of miR-211 in PCa cell lines and tissues was measured by reverse transcription-quantitative PCR (qPCR), revealing that miR-211 was downregulated in PCa cell lines and tissues. Further analysis revealed that low miR-211 was associated with the tumor stage and Gleason score. With the assistance of miR-211 mimics and inhibitor, it was also revealed that the overexpression of miR-211 could inhibit PCa cell proliferation in vitro. Conversely, downregulated miR-211 expression promotes PCa cell proliferation. In addition, the secreted protein acidic and rich in cysteine (SPARC) was identified as a target of miR-211 in the PCa cell lines, and SPARC expression was inversely associated with miR-211. In conclusion, it was demonstrated that the miR-211 expression was downregulated in PCa cell lines and tissues. Additionally, miR-211 could inhibit PCa cell proliferation partially by downregulating SPARC. Therefore, miR-211 may be a potential therapeutic target for PCa treatment in the future.

Keywords: microRNA-211; proliferation; prostate cancer; secreted protein acidic and rich in cysteine.

Figure 1.

miR-211 expression is downregulated in PCa cell lines and tissues. (A) reverse transcription-quantitative polymerase chain reaction analysis of miR-211 expression in 36 pairs of PCa tissues and their matched normal prostate tissues. The expression of miR-211 was normalized to U6 small nuclear RNA. (B) The expression of miR-211 in PCa tissues was significantly lower than in adjacent tissues. (C) Expression levels of miR-211 in the DU145 and PC-3 PCa cell lines compared with NHPE cells. **P<0.01 and ***P<0.001. miR-211, microRNA-211; PCa, prostate cancer; NHPE, normal human prostate epithelium.

Figure 2.

Upregulation of miR-211 inhibits cell proliferation. (A) CCK-8 assay revealed that the PCa cell lines DU145 and PC-3 had a significantly higher cell proliferation rate than NHPE cells. (B) Transfection with miR-211 mimics enhanced the expression of miR-211, whereas the miR-211 inhibitor repressed the expression of miR-211 in DU145 cells. (C) Transfection with miR-211 mimics enhanced the expression of miR-211 and miR-211 inhibitor can repress the expression of miR-211 in the PC-3 cells. (D) CCK-8 proliferation assay revealed that the overexpression of miR-211 significantly inhibited the growth rate of cells compared with that of the control in DU145 cells. Conversely, transfection with miR-211 inhibitor significantly promoted the proliferation of the DU145 cells. (E) CCK-8 proliferation assay revealed that the overexpression of miR-211 significantly inhibited the growth rate of cells compared with that of the control in PC-3 cells. Conversely, miR-211 inhibitor significantly promoted the proliferation of the PC-3 cells. *P<0.05, **P<0.01 and ***P<0.001 vs. control. miR-211, microRNA-211; PCa, prostate cancer; CCK-8, Cell Counting kit-8; NHPE, normal human prostate epithelium.

Figure 3.

miR-211 regulation of SPARC expression. (A) A computational algorithm revealed that the putative miR-211-binding sequence was in the 3′-UTR of SPARC. (B) RT-qPCR analysis of SPARC mRNA expression in PCa tissues and matched normal prostate tissues. (C) Western blot analysis of SPARC protein expression in PCa tissues and matched normal prostate tissues. (D) RT-qPCR analysis of SPARC expression in the DU145 cells transfected with miR-211 mimics or miR-211 inhibitor or negative control miRNA. The expression of SPARC was normalized to that of GAPDH. (E) RT-qPCR analysis of SPARC expression in the PC-3 cells transfected with miR-211 mimics or miR-211 inhibitor or negative control miRNA. GAPDH was also detected as a loading control. **P<0.01 and ***P<0.001. miR-211, microRNA-211; SPARC, secreted protein acidic and rich in cysteine; 3′-UTR, 3′-untranslated region; RT-qPCR, reverse transcription-quantitative polymerase chain reaction; PCa, prostate cancer.

Figure 4.

Effect of SPARC on cell proliferation. (A) RT-qPCR analysis of the mRNA level of SPARC in the PCa DU145 and PC-3 cell lines transfected with si-NC or si-SPARC. (B) CCK-8 proliferation assay revealed that knockdown of SPARC by si-SPARC significantly inhibited the proliferation of the DU145 cells compared to the negative control. (C) The CCK-8 proliferation assay revealed that knockdown of SPARC by si-SPARC significantly inhibited the proliferation of the PC-3 cells compared to the negative control. *P<0.05, **P<0.01 and ***P<0.001 vs. si-NC. si-SPARC, small interfering RNA targeted at secreted protein acidic and rich in cysteine; NC, negative control; PCa, prostate cancer; CCK-8, cell counting kit-8; OD, optical density.