Oncogenic circDHTKD1 promotes tumor growth and metastasis of oral squamous cell carcinoma in vitro and in vivo via upregulating miR-326-mediated GAB1

Circular RNAs (circRNAs) have been extensively elucidated with regard to their significant implications in oral squamous cell carcinoma (OSCC). This study performed the functional investigation of circRNA dehydrogenase E1 and transketolase domain containing 1 (circDHTKD1) in OSCC. RNA expression levels of different molecules were measured via quantitative real-time polymerase chain reaction (qRT-PCR). Cellular behaviors were detected by 3-(4, 5-dimethylthiazol-2-y1)-2,5-diphenyl tetrazolium bromide (MTT) for cell viability, colony formation assay for clonal capacity, flow cytometry for cell apoptosis, wound healing assay for migration, and transwell assay for migration/invasion. Western blot was used for analyzing protein expression. RNA pull-down and dual-luciferase reporter assays were applied to assess the binding between targets. A xenograft tumor model was established in nude mice for in vivo experiments. Our expression analysis revealed that circDHTKD1 was upregulated in OSCC tissues and cells. circDHTKD1 knockdown was shown to impede OSCC cell growth and metastasis but motivate apoptosis. Additionally, circDHTKD1 served as a microRNA-326 (miR-326) sponge and the function of circDHTKD1 was achieved by sponging miR-326 in OSCC cells. Also, miR-326 inhibited OSCC development via targeting GRB2-associated-binding protein 1 (GAB1). circDHTKD1 could sponge miR-326 to alter GAB1 expression. Furthermore, circDHTKD1 contributed to OSCC progression in vivo via the miR-326/GAB1 axis. These data disclosed a specific circDHTKD1/miR-326/GAB1 signal axis in governing the malignant progression of OSCC, showing the considerable possibility of circDHTKD1 as a predictive and therapeutic target for clinical diagnosis and treatment of OSCC.

Expression of GAB1 in ER-positive breast cancer and its effect on MCF-7 cells’ metastasis / 西安交通大学学报(医学版)

【Objective】 To evaluate the expression of GAB1 in ER-positive breast cancer and its effect on MCF-7 cells’ metastasis. 【Methods】 The expression of GAB1 in ER-positive breast cancer tissues was detected by immunohistochemistry. We analyzed the relationship of GAB1 expression with the patients’ clinicopathological features and prognosis. The invasion and metastasis abilities of MCF-7 cells after silencing GAB1 expression were observed by Transwell assay. The effect of GAB1 expression on the EMT of breast cancer cells was analyzed by Western blotting. 【Results】 Immunohistochemical staining showed that GAB1 expression had significant correlation with lymph node metastasis(P=0.014) and stage(P=0.011). Transwell results showed that shGAB1 significantly inhibited the migration and invasion of human breast cancer MCF-7 cells. Western blotting results showed that shGAB1 significantly increased E-cadherin expression and decreased Vimentin expression. Kaplan-Meier analysis revealed that ER-positive breast cancer patients with high GAB1 expression tumors had a significantly worse relapse-free survival rate than those with low GAB1 expression tumors(P<0.001). Multivariate analysis showed that stage and GAB1 expression were independent predictors of survival. 【Conclusion】 GAB1 is highly expressed in ER-positive breast cancer. ShGAB1 expression can inhibit the migration, invasion and EMT of breast cancer cells. GAB1 might be used as one of the valuable markers for prognosis in patients with ER-positive breast cancer.

Effect of silencing Gab1 expression on cholangiocarcinoma cell line HUCCA-1 and its correlation with PI3K/Akt pathway / 天津医药

Objective To explore the functionalternation of human cholangiocarcinoma cell line HUCCA-1 by silenc?ing Gab1 expression;to detect its effect on PI3KCA and Akt1 expression at protein and mRNA levels and to explore the role of Gab1,PI3KCA and Akt1 expressions in the malignant behavior of cholangiocarcinoma. Methods Gab1 siRNA was trans? fected into cholangiocarcinoma cell line HUCCA-1. Proliferation, apoptosis, migration/invasion of cells were examined by MTT, flow cytometry and Transwell assay respectively after transfection. PI3KCA and Akt1 expressions were detected by Western blotting and qPCR. Results Transfection efficiency was satisfactory and reaches 65%~70%;PI3KCA and Akt1 expressions were down-regulated at both protein and mRNA levels upon silencing of Gab1. Meanwhile, proliferations of HUCCA-1 cells were inhibited (P<0.01);apoptosis rate increases(P<0.05);and migration and invasion were both inhibit?ed upon Gab1 silencing(P<0.05). Conclusion The proliferation, migration and invasion are all inhibited while apoptosis is attenuated after Gab1 was down-regulated by Gab1 siRNA transfection. PI3KCA and Akt1 expressions are up-regulated with down-regulation of Gab1. Therefore, Gab1 may enhance the maglinant behavior of cholangiocarcinoma cells through up-regulating PI3KCA and Akt1 expression and it can be used as a candidate for cholangiocarcinoma therapy.