YWHAB knockdown inhibits cell proliferation whilst promoting cell cycle arrest and apoptosis in colon cancer cells through PIK3R2.

Abstract

Colon cancer is one of the most common causes of cancer-associated mortality. Tyrosine 3-monooxygenase/tryptophan 5-monooxygenase activation protein β (YWHAB) has been reported to be aberrantly expressed in human colon cancer cells following alltrans retinoic acid treatment. PI3K regulatory subunit 2 (PIK3R2) has also been identified as a gene associated with colon cancer metastasis and tumor progression. The present study aimed to determine the role of YWHAB in colon cancer in addition to its detailed reaction mechanism. The expression levels of YWHAB and PIK3 'A0* R2 before or after transfection of YWHAB interference plasmids or PIK3R2 overexpression plasmids were examined by reverse transcription-quantitative PCR and western blotting. PI flow cytometry, Cell Counting Kit-8 and TUNEL assays were performed to measure the extent of cell cycle progression, proliferation and apoptosis. Additionally, the expression levels of G1-S cell-cycle transition regulator cyclin D1 and G1-checkpoint CDK inhibitor p21 and apoptosis marker proteins Bcl2 and Bax were assessed using western blotting. Subsequently, the Monarch Initiative database (https://monarchinitiative.org/) predicted the binding of YWHAB and PIK3R2, following which co-immunoprecipitation assay was utilized to assess their potential interaction. Furthermore, western blotting was performed to examine the expression levels of PI3K/AKT signaling pathway markers. It was revealed that YWHAB expression was upregulated in colon cancer cells compared with HIEC-6 human intestinal epithelial cells. Functionally, YWHAB depletion by transfection of YWHAB interference plasmids was demonstrated to suppress the proliferation of colon cancer cells whilst promoting cell cycle arrest at the G0/G1 phase and apoptosis, decreasing cyclin D1 and Bcl2 expression, and increasing p21 and Bax expression. Additionally, YWHAB was verified to bind to PIK3R2 and YWHAB knockdown decreased PIK3R2 expression. PIK3R2 overexpression by transfection of PIK3R2 overexpression plasmids reversed the effects of YWHAB knockdown on cell proliferation, cycle arrest, apoptosis, and apoptotic and cell cycle proteins in colon cancer cells. YWHAB knockdown reduced the levels of p-PI3K/PI3K and p-AKT/AKT and PIK3R2 overexpression also reversed the effects of YWHAB knockdown on the expression of PI3K/AKT signaling markers. In conclusion, these data suggest that YWHAB can activate the PI3K/AKT signaling pathway and participate in the malignant progression of colon cancer by targeting PIK3R2, which provides novel insights into the mechanism of colon cancer.