Long non‑coding RNA Linc‑pint mediates the progression of colorectal cancer by regulating miRNA‑21

Objective To investigate the biological function and molecular mechanism of long non-coding RNA Linc‑pint in colorectal cancer.

Methods Quantitative real‑time quantitative （qRT‑PCR） was performed to detect the expression level of Linc‑pint in 31 pairs of colorectal cancer tumor and adjacent normal tissues； correlation between the expression level of Linc‑pint and the clinicopathological characteristics was analyzed by the chi‑square test. Kaplan-Meier survival analysis was used to assess the relationship between Linc‑pint expression level and the prognosis of patients. Cox regression model was used to analyze the relationship between clinicopathological characteristics and the prognosis of patients. Expression level of Linc‑pint were detected by qRT‑PCR in 5 common colorectal cancer cell lines. Effect of Linc‑pint on cell proliferation， invasion and migration was measured by cell counting kit‑8 assay， Transwell assay and harvested xenografts from nude mice. qRT‑PCR was performed to detect the expression level of Linc‑pint's target gene micro RNA（miR）‑21 in 31 pairs of colorectal cancer tumor tissues and adjacent normal tissues. Pearson correlation coefficient was used to assess the correlation between Linc‑pint and miR‑21. qRT‑PCR was used to detect the expression of overexpression of Linc‑pint on miR‑21 in colorectal cancer cells.

Results Expression level of Linc‑pint in normal tissues （3.95±1.16） was significantly higher than that in colorectal cancer tissues （2.74±0.95） （t=6.17， P<0.05）. Overall survival rate of patients with high expression of Linc‑pint was 62.5%， which was significantly higher than that of patients with low expression of Linc‑pint （34.3%， P<0.05）. The proliferation， invasion and migration of CRC cells were inhibited after overexpression of Linc‑pint. In colorectal cancer tumor and adjacent normal tissues， Linc‑pint and miR‑21 showed opposite expression in tumor tissues and were negatively correlated （r=-0.288 and -0.908， both P<0.05）.

Conclusion Linc‑pint acts as a tumor suppressor by down‑regulating the expression level of miR‑21 to inhibit the proliferation， invasion and migration of colorectal cancer.