RESUMO
Cholangiocarcinoma (CCA) is a highly invasive type of cancer with insidious onset and high mortality. Polypyrimidine tract-binding protein 1 (PTBP1) is highly over-expressed in various types of tumor tissues, which contributes to cancer progression. But the role of PTBP1 in CCA has not been explored yet. In this study, we aim to investigate the function of PTBP1 in CCA. Therefore, we used publicly available data from the cancer genome atlas (TCGA) to evaluate the dysregulation of PTBP1 in CCA. The results showed that the PTBP1 is significantly up-regulated in CCA tissues compared to the matched non-tumor tissues (P < 0. 05). We assessed the effects of PTBP1 on the growth of CCA cell lines RBE and HuH28 by performing CCK-8 and plate colony formation assays. The results showed that overexpression of PTBP1 significantly promoted the growth (P < 0. 01) of CCA cells, whereas knockdown of PTBP1 exhibited opposite effects. Transwell and Invasion assays revealed that overexpression of PTBP1 significantly promotes the migration and invasion of CCA cells (P < 0. 001), whereas knockdown of PTBP1 exhibited opposite effects (P < 0. 001). The RNA sequencing (RNA-seq) analysis in PTBP1-depleted cells showed that the up-regulated genes are significantly enriched in p53 signaling pathway, while the down-regulated genes are represented by cholesterol metabolism, Rho GTPase and TGF-β pathways. Then, the alternative splicing analysis revealed that inhibition of PTBP1 led to series of aberrant alternative splicing events, including several cancer-associated ones, such as splicing events within the TGF-β regulator TGIF1 and the p53 activity-correlated gene GNAS. These results indicate that PTBP1 promotes the progression of CCA likely by regulating the transcriptome alternative splicing to influence multiple cancer-associated signaling pathways.
RESUMO
@#[Abstract] Objective: To explore the effect of circ_0001429 on proliferation and apoptosis of bladder cancer cells by regulating miR-139-5p/TGF-interacting factor 1（TGIF1）axis. Methods: The expression of circ_0001429 in bladder cancer cell lines SW780, T24, 5637 and human bladder epithelial SV-HUC-1 cells were detected by RT-qPCR. Targeted regulatory relationship between circ_0001429 and miR-139-5p as well as miR-139-5p and TGIF1 was measured by Dual luciferase reporter gene assay. T24 cells were divided into NC group, sh-circ_0001429 group, miR-139-5p mimics group, sh-TGIF1 group, pcDNA-circ_0001429+sh-TGIF1 group, miR-139-5p mimics+pcDNA-TGIF1 group and sh-circ_0001429+miR-139-5p inhibitor group. Western blotting was used to detect the expression level of TGIF1 in each group. CCK-8 method, Transwell experiment and Flow cytometry were used to detect the effects of circ_ 0001429, miR-139-5p and TGIF1 on proliferation, invasion, migration and apoptosis of T24 cells, respectively. Results: Circ_0001429 was highly expressed in three bladder cancer cell lines (P<0.01). Knockdown of circ_0001429 significantly inhibited proliferation, invasion and migration of T24 cells while promoted the level of cell apoptosis (P<0.05 or P<0.01). The results of Dual luciferase reporter gene assayconfirmedthatthereisatargetingrelationshipbetweencirc_0001429andmiR-139-5p as well as between miR-139-5p and TGIF1. Overexpression of miR-139-5p significantly inhibited the proliferation, invasion and migration of T24 cells while promoted the level of cell apoptosis (all P<0.01). Recovery experiments further confirmed that the competitive binding of circ_0001429 and TGIF1 to miR-139-5p promoted the proliferation, invasion and migration of T24 cells while inhibited the level of cell apoptosis (all P<0.01). Conclusion: Circ_0001429 promotes proliferation, invasion and migration and inhibits apoptosis of bladder cancer T24 cells by competing with TGIF1 to bind to miR-139-5p.