Effect of 5′tiRNA-Val-CAC on proliferation and its pathological significance in colorectal cancer

Objective To investigate the expression of 5′tiRNA-Val-CAC in colorectal cancer (CRC), its clinicopathological significance and its effect on tumor growth and proliferation.

Methods The expression profile of tRNA derived small RNA (TDSR) was analyzed and the expression level of 5′tiRNA-Val-CAC was detected by quantitative real-time reverse transcriptase-polymerase chain reaction (qRT-PCR). RNA in situ hybridization (RISH) was used to detect the positive expression of 5′tiRNA-Val-CAC in CRC tissues and normal adjacent tissues of 82 CRC patients. The correlation between the positive expression and clinicopathological features of patients was statistically analyzed. CCK-8 experiment and cell cloning plate experiment were used to observe the effect of 5′tiRNA-Val-CAC on the growth and proliferation of colorectal cancer cells.

Results qRT-PCR results showed that the expression level of 5′tiRNA-Val-CAC in CRC tissues was significantly higher than that in adjacent normal colorectal tissues(t=9.111, P=0.012); the expression levels of 5′tiRNA-Val-CAC in CRC cell lines SW620 and HCT116 were higher than those in normal intestinal epithelial cells (HIEC), the difference was statistically significant (t=11.475, 7.158, P=0.008, 0.019). RISH experimental results showed that positive rate of 5′tiRNA-Val-CAC expression in CRC tissues was 82.93%(68/82), and was 7.32%(6/82) in adjacent normal tissues, which showed a significant differences(χ²=31.444, P < 0.001). Highly positive expression of 5′tiRNA-Val-CAC was correlated with tumor size(χ²=6.924, P < 0.05) and tumor differentiation(χ²=25.030, P < 0.05), but had no correlations with gender, age, lesion location, depth of invasion, lymph node metastasis and TNM stage (P>0.05). CCK-8 experiment and cell cloning plate experiment showed that the proliferation activity of overexpressed 5′tiRNA-Val-CAC colorectal cancer cells and the number of cell clones increased, while proliferation activity of CRC cells knockdown of 5′tiRNA-Val-CAC expression and the number of cell clones decreased compared with the control group(P < 0.05).

Conclusion 5′tiRNA-Val-CAC that is highly expressed in CRC tissues can promote the proliferation and growth of CRC cells and affect the progression and prognosis of CRC. 5′tiRNA-Val-CAC may be a molecular marker of CRC proliferation and can be used as an index for diagnosis and prognosis of CRC.