A CGA/EGFR/GATA2 positive feedback circuit confers chemoresistance in gastric cancer
Tianyu Cao, … , Robert J. Coffey, Xiaodi Zhao
Tianyu Cao, … , Robert J. Coffey, Xiaodi Zhao
Published March 15, 2022
Citation Information: J Clin Invest. 2022;132(6):e154074. https://doi.org/10.1172/JCI154074.
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Research Article Gastroenterology Oncology

A CGA/EGFR/GATA2 positive feedback circuit confers chemoresistance in gastric cancer

Abstract

De novo and acquired resistance are major impediments to the efficacy of conventional and targeted cancer therapy. In unselected gastric cancer (GC) patients with advanced disease, trials combining chemotherapy and an anti-EGFR monoclonal antibody have been largely unsuccessful. In an effort to identify biomarkers of resistance so as to better select patients for such trials, we screened the secretome of chemotherapy-treated human GC cell lines. We found that levels of CGA, the α-subunit of glycoprotein hormones, were markedly increased in the conditioned media of chemoresistant GC cells, and CGA immunoreactivity was enhanced in GC tissues that progressed on chemotherapy. CGA levels in plasma increased in GC patients who received chemotherapy, and this increase was correlated with reduced responsiveness to chemotherapy and poor survival. Mechanistically, secreted CGA was found to bind to EGFR and activate EGFR signaling, thereby conferring a survival advantage to GC cells. N-glycosylation of CGA at Asn52 and Asn78 is required for its stability, secretion, and interaction with EGFR. GATA2 was found to activate CGA transcription, whose increase, in turn, induced the expression and phosphorylation of GATA2 in an EGFR-dependent manner, forming a positive feedback circuit that was initiated by GATA2 autoregulation upon sublethal exposure to chemotherapy. Based on this circuit, combination strategies involving anti-EGFR therapies or targeting CGA with microRNAs (miR-708-3p and miR-761) restored chemotherapy sensitivity. These findings identify a clinically actionable CGA/EGFR/GATA2 circuit and highlight CGA as a predictive biomarker and therapeutic target in chemoresistant GC.

Authors

Tianyu Cao, Yuanyuan Lu, Qi Wang, Hongqiang Qin, Hongwei Li, Hao Guo, Minghui Ge, Sarah E. Glass, Bhuminder Singh, Wenyao Zhang, Jiaqiang Dong, Feng Du, Airong Qian, Ye Tian, Xin Wang, Cunxi Li, Kaichun Wu, Daiming Fan, Yongzhan Nie, Robert J. Coffey, Xiaodi Zhao

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Figure 7

miR-708-3p and miR-761 sensitize chemoresistant GC cells by targeting CGA.

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miR-708-3p and miR-761 sensitize chemoresistant GC cells by targeting CG...
(A) Diagram of screening for CGA-targeting miRNAs. Details can be found in Supplemental Table 9. (B) Expression of CGA-targeting miRNAs in SGC7901 and MDR cells. (C) Immunoblotting of CGA in MDR cells transfected with indicated miRNA mimics. (D) Top: Diagram of the predicted binding sites between indicated miRNAs and CGA 3′-UTR. Bottom: Luciferase activity derived from the CGA 3′-UTR reporter construct after cotransfection with indicated miRNA mimics. (E) Immunoblotting of CGA in CGA–/– SGC7901ADR cells transfected with indicated constructs and/or miRNA mimics. (F) Viability of CGA-WT and -KO SGC7901ADR cells transfected with indicated constructs and/or miRNA mimics and treated with chemotherapy. (G and H) Nude mice (n = 7–8) were implanted subcutaneously with SGC7901ADR cells. When the tumor size reached 100 mm3, mice received indicated treatment every 3 days (G; fluorouracil, 20 mg/kg, i.p. injection; miRNA prodrugs, 1 nmol/mouse intratumoral injection). Tumor volume and tumor weight were measured (H). Data are presented as mean ± SEM. *P < 0.05; **P < 0.01 by 1-way ANOVA followed by Dunnett’s multiple-comparison test (B, D, and F) or by 1-way or repeated-measures ANOVA with Bonferroni’s post hoc test (H).