ABSTRACT
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.
ABSTRACT
@#[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.
ABSTRACT
As a nuclear transcription repressor,the functions of TGIF are complicated,not only represses target genes expression directly,but also takes part in the regulation of multiple important cellular signaling pathways,which are associated with the differentiation of cells and tissues,inflammation,metabolism and tumors.In past few years,more and more studies on the role of TGIF in tumors suggest TGIF may be a new therapy target in the diagnosis and treatment of tumours.This article mainly reviews the research progress of TGIF in some signaling pathways like TGF-β,MAPK,PI3K/AKT,and tumours like hepatocellular carcinoma,lung carcinoma and urinary tract urothelial carcinoma.
ABSTRACT
TGF-beta1 is well known to induce Ig germ-line alpha (GLalpha) transcription and subsequent IgA isotype class switching recombination (CSR). Homeodomain protein TG-interacting factor (TGIF) and E3-ubiquitin ligases TGIF interacting ubiquitin ligase 1 (Tiul1) are implicated in the negative regulation of TGF-beta signaling. In the present study, we investigated the roles of Tiul1 and TGIF in TGFbeta1-induced IgA CSR. We found that over-expression of Tiul1 decreased TGFbeta1-induced GLalpha promoter activity and strengthened the inhibitory effect of Smad7 on the promoter activity. Likewise, overexpression of TGIF also diminished GLalpha promoter activity and further strengthened the inhibitory effect of Tiul1, suggesting that Tiul1 and TGIF can down-regulate TGFbeta1-induced GLalpha expression. In parallel, overexpression of Tiul1 decreased the expression of endogenous IgA CSR-predicitive transcripts (GLT(alpha), PST(alpha), and CT(alpha)) and TGFbeta1-induced IgA secretion, but not GLT(gamma3) and IgG3 secretion. Here, over-expressed TGIF further strengthened the inhibitory effect of Tiul1. These results suggest that Tiul1 and TGIF act as negatively regulators in TGFbeta1-induced IgA isotype expression.
Subject(s)
Down-Regulation , Immunoglobulin A , Immunoglobulin Class Switching , Immunoglobulin G , Ligases , Recombination, Genetic , Transforming Growth Factor beta , Transforming Growth Factor beta1 , UbiquitinABSTRACT
Objective To investigate the effect of TGIF on apoptosis of TGF-?-induced gastric canceer cell.Methods After TGIF was stably transfected into gastric cancer cell line BGC823,apoptosis was examined with flow cytometry,and the expressions of TGIF,caspase8 and caspase9 were analyzed with Western blot.Results The apoptosis rate of BGC823 cells with the treatment of TGF-? obviously increased,and was accompanied by activation of caspase9 but not caspase8.Moreover,compared with controls,pcDNA3.1-TGIF-transfected BGC823 cells significantly decreased the sensitivity of TGF-?-induced apoptosis.Conclusions TGF-? induced the apoptosis of gastric cancer cell BGC823 via caspase9 pathway;furthermore,TGIF could inhibit TGF-?-induced apoptosis.