Promoting effect of PAX5-activated lncRNA UASR1 on growth of colorectal cancer by regulating the mTOR pathway.

OBJECTIVE: To study the expression of long non-coding ribonucleic acid (lncRNA) UNC5B antisense RNA 1 (UASR1) in colorectal cancer (CRC) and its biological functions, and to discuss the regulatory effect of the transcription factor on lncRNA UASR1. PATIENTS AND METHODS: The expressions of lncRNA UASR1 in the CRC tissues and cells were detected via quantitative Reverse Transcription-Polymerase Chain Reaction (qRT-PCR) assay. After the expression of lncRNA UASR1 was interfered, the change in the CRC cell proliferation ability was investigated through cell counting kit-8 (CCK-8) assay and colony formation assay. respectively. Changes in cell cycle distribution and apoptosis rate in CRC cells after transfection of small-interfering UASR1 (si-UASR1) were detected using flow cytometry. Potential transcription factors binding UASR1 promoter region were analyzed through bioinformatics. The change in the UASR1 expression was measured through the qRT-PCR assay after the paired box 5 (PAX5) expression was interfered. Following the interference in the expressions of PAX5 and UASR1, expression changes in the molecular markers of the mammalian target of rapamycin (mTOR) signaling pathway were detected via Western blotting assay. RESULTS: The qRT-PCR results indicated that the UASR1 expression was up-regulated in 39/45 CRC tissues, and it identically presented the up-regulated expression level in the CRC cells. After the UASR1 expression was interfered, the CRC cell proliferation ability was degraded according to the CCK-8 assay and colony formation assay. Based on the flow cytometry results, compared with the small-interfering-negative control (si-NC) group, the cell cycle was arrested in the G1/G0 phase in the siUASR1 group, and apoptosis rate increased. Bioinformatics and qRT-PCR results showed that the transcription factor PAX5 regulated the UASR1 expression. The Western blotting assay indicated that the expressions of the molecular markers of the mTOR signaling pathway were changed after the expressions of PAX5 and UASR1 were interfered. CONCLUSIONS: The transcription factor PAX5 promotes the expression of lncRNA UASR1 in CRC. The highly expressed UASR1 facilitates the malignant proliferation of CRC via the mTOR signaling pathway.