Role and mechanism of circular RNA protein arginine methyltransferase 5 in proliferation, migration of colorectal cancer cells

Abstract

Objective To evaluate the role of circular RNA protein arginine methyltransferase 5 (circPRMT5) in the genesis and progression of colorectal cancer. Methods From January 2013 to December 2017, 96 patients with colorectal cancer who underwent radical resection in Department of General Surgery, Jiading District Central Hospital Affiliated to Shanghai Medical College of Health were collected. The expression of circPRMT5 in colorectal cancer tissues was examined by real-time polymerase chain reaction (RT-PCR). The correlation between circPRMT5 expression level and age, gender, tumor size, tumor location, pathological differentiation, TNM stage, lymph node metastasis of patients with colorectal cancer was analyzed. The SW620 and LOVO cells were divided into control group, circPRMT5-lenti group and circPRMT5-shRNA-lenti group according to different interventions. The effects of circPRMT5 expression level on viability, apoptosis, mitochondrial membrane potential and migration of SW620 and LOVO cells were detected. The influence of circPRMT5 expression level on E-cadherin, Slug, N-cadherin and vimentin was determined by Western blotting method. The potential target miRNA of circPRMT5 was predicted by Starbase V2.0. Student′s t test, analysis of variance and chi-square test were performed for statistical analysis. Results The results of RT-PCR showed that the expression of circPRMT5 in colorectal cancer tissues was higher than that of adjacent cancer tissues (2.167±0.345 vs. 1.103±0.144), and the difference was statistically significant (t=26.847, P<0.01). The circPRMT5 expression level was positively correlated with tumor size, TNM stage, lymph node metastasis and distant metastasis (χ2=6.010, 10.971, 5.321 and 6.272, all P<0.05). The upregulation of circPRMT5 expression could promote proliferation and migration of SW620 and LOVO cells. The circPRMT5 downregulation could inhibit cell proliferation, induce apoptosis and decrease mitochondrial membrane potential. The results of Western blotting indicated that, compared with those of control group, the expression of Slug, N-cadherin and vimentin increased in circPRMT5-lenti group (1.023±0.038 vs. 2.105±0.042, 1.051±0.309 vs. 2.277±0.111, 1.055±0.040 vs. 2.002±0.537, respectively), however the expression of E-cadherin decreased (2.074±0.214 vs. 0.627±0.023), and the differences were statistically significant (t=31.817, 22.065, 14.536 and 9.148, all P<0.01). Compared with the control group, the expression of Slug, N-cadherin and vimentin decreased in circPRMT5-shRNA-lenti group (1.023±0.038 vs. 0.585±0.023, 1.051±0.309 vs. 0.616±0.043, 1.055±0.040 vs. 0.537±0.022), while the expression of E-cadherin increased (2.074±0.214 vs. 2.756±0.148), and the differences were statistically significant (t=-13.795, -14.252, -11.794 and -13.116, all P<0.05). A total of 21 miRNAs might have potential binding sites with circPRMT5 predicted by Starbase V2.0 software. The expression of miRNA4735-3p, miRNA202-3p, miRNA326, let-7i-5p and miRNA4500 was negatively correlated with circPRMT5 expression in both SW620 and LOVO cells confirmed by RT-PCR. Conclusion CircPRMT5 is an important oncogenic gene in the genesis and progress of colorectal cancer, and may have certain potential application prospect in the research and development for colorectal cancer. Key words: Colorectal neoplasms; circPRMT5; Epithelial-mesenchymal transition