MicroRNA-331 inhibits development of gastric cancer through targeting musashi1

Abstract

Background: The molecular mechanisms involved in microRNAs (miRNAs) have been extensively investigated in gastric cancer (GC). However, how miR-331 regulates GC pathogenesis remains unknown.

Aim: To illuminate the effect of miR-331 on cell metastasis and tumor growth in GC.

Methods: The qRT-PCR, CCK8, Transwell, cell adhesion, Western blot, luciferase reporter and xenograft tumor formation assays were applied to explore the regulatory mechanism of miR-331 in GC.

Results: Downregulation of miR-331 associated with poor prognosis was detected in GC. Functionally, miR-331 suppressed cell proliferation, metastasis and tumor growth in GC. Further, miR-331 was verified to directly target musashi1 (MSI1). In addition, miR-331 inversely regulated MSI1 expression in GC tissues. Furthermore, upregulation of MSI1 weakened the inhibitory effect of miR-331 in GC.

Conclusion: miR-331 inhibited development of GC through targeting MSI1, which may be used as an indicator for the prediction and prognosis of GC.

Keywords: Gastric cancer; Metastasis; MicroRNA-331; Musashi1; Tumor growth.

Figure 1

Downregulation of miR-331 associated with prognosis was detected in gastric cancer. A: The mRNA expression of miR-331 was examined in gafstric cancer (GC) tissues. B: MiR-331 expression was determined in MKN-45, MGC-803, SGC-7901, and GES1 cells. C and D: Low miR-331expression was correlated with shorter DFS and OS time in GC patients. ^aP < 0.05, ^bP < 0.01.

Figure 2

MiR-331 inhibited gastric cancer cell viability in vitro and vivo. A: MiR-331 mRNA expressions was determined in MKN-45 cells with miR-331 mimic or inhibitor. B: Cell proliferation was regulated by miR-331 mimic or inhibitor in MKN-45 cells. C: Photographs of gastric cancer (GC) tumors in miR-NC (n = 5) or miR-331 mimics (n = 5) group. Ten mice were used for xenograft tumor formation assay. Here are five of the results. D: In nude mice with miR-NC or miR-331 mimics, GC tumor volume was measured every week. E: Ki-67-stained sections of transplanted tumors in miR-NC or miR-331 mimics group. ^aP < 0.05, ^bP < 0.01.

Figure 3

MiR-331 inhibited cell metastasis in gastric cancer. A-C: MKN-45 cell migration and invasion were regulated by miR-331 mimic or inhibitor. D: MiR-331 regulated expressions of E-cadherin, N-cadherin and Vimentin in MKN-45 cells. ^aP < 0.05, ^bP < 0.01.

Figure 4

MiR-331 directly targets musashi1. A: There are binding sites between musashi1 (MSI1) with miR-331. B: Luciferase reporter assay (C, D) MSI1 expression regulated by miR-331 mimics or inhibitor was observed in MKN-45 cells. ^aP < 0.05, ^bP < 0.01.

Figure 5

Musashi1 upregulation weakened miR-331 inhibitory effect in gastric cancer. A: Musashi1 (MSI1) expression was detected in gastric cancer (GC) tissues. B: MiR-331 negatively regulated MSI1 expression in GC tissues. C and D: The mRNA and protein MSI1 expressions were detected in MKN-45 cells containing MSI1 vector and miR-331 mimic. E: Cell proliferation was identified in MKN-45 cells containing MSI1 vector and miR-331 mimic. F: Protein expressions of E-cadherin, N-cadherin and Vimentin in MKN-45 cells with MSI1 vector and miR-331 mimic (G) Cell migration and invasion were identified in MKN-45 cells containing MSI1 vector and miR-331 mimic. ^bP < 0.01.