Protease-activated receptor 2 stabilizes Bcl-xL and regulates EGFR–targeted therapy response in colorectal cancer

• Published in: Cancer letters 2021-10, Vol.517, p.14-23
• Main Authors: Li, Weiwei, Ma, Yiming, He, Longmei, Li, Hongwei, Chu, Yi, Jiang, Zheng, Zhao, Xinhua, Nie, Yongzhan, Wang, Xishan, Wang, Hongying
• Format: Article
• Language: English
• Subjects: Animals; Antibodies; Apoptosis; Apoptosis - genetics; Bcl-2 protein; Bcl-x protein; bcl-X Protein - genetics; Bcl-xL; Caco-2 Cells; Carcinogenesis - genetics; Cell death; Cell Line; Cell Line, Tumor; Cell survival; Colorectal cancer; Colorectal carcinoma; Colorectal Neoplasms - genetics; EGFR; Epidermal growth factor receptors; ErbB Receptors - genetics; Gene silencing; HCT116 Cells; HEK293 Cells; HT29 Cells; Humans; Male; Medical prognosis; Mice; Mice, Inbred NOD; Mice, SCID; Microenvironments; Mutation - genetics; PAR2; Phosphatase; Phosphorylation; Phosphorylation - genetics; Plasmids; Proteasomes; Proteins; Receptor, PAR-2 - genetics; RING finger proteins; RNF152; Sensors; Signal Transduction - genetics; siRNA; Tumor Microenvironment - genetics; Tumorigenesis; Ubiquitin-protein ligase; Ubiquitin-Protein Ligases - genetics; Ubiquitination; Xenografts
• ISSN: 0304-3835; 1872-7980
• DOI: 10.1016/j.canlet.2021.05.040

The Bcl-2 homolog Bcl-xL is emerging as a key factor in tumorigenesis due to its prominent pro-survival and cell death-independent functions. However, the regulation of Bcl-xL by microenvironment and its implication in cancer therapy of colorectal carcinoma (CRC) are unclear. Here, we demonstrated that Bcl-xL expression was positively associated with protease-activated receptor 2 (PAR2) in CRC. Activation of PAR2 stabilized Bcl-xL protein in a proteasome-dependent manner, whereas E3 ligase RING finger protein 152 (RNF152) accelerated the ubiquitination and degradation of Bcl-xL. RNF152 silencing by specific siRNAs rescued the expression of Bcl-xL in PAR2-deficient cells. Moreover, RNF152 physically interacted with Bcl-xL, which was disturbed by PAR2 activation. Further studies with serial mutation of Bcl-xL revealed that phosphorylation of Bcl-xL at S145 reduced its binding affinity for RNF152 and stabilized Bcl-xL. Importantly, inhibition of PAR2 signaling by its gene silencing or specific chemical inhibitors increased apoptosis induced by different EGFR-targeted therapies. In patient-derived xenograft model, inhibition of PAR2 increased the response of CRC to different EGFR-targeted therapies. These results indicate that PAR2 stabilizes Bcl-xL by altering RNF152 signaling and that PAR2 inhibition sensitizes CRC to EGFR-targeted therapies in vivo. •E3 ligase RNF152 promotes Bcl-xL degradation via ubiquitin-proteasome pathway.•PAR2 activation induces Bcl-xL phosphorylation at S145 and stabilizes Bcl-xL through disturbing its interaction with RNF152.•Inhibition of PAR2 sensitizes colorectal cancer to different EGFR-targeted therapies in PDX model.