Integrin β6/Annexin A2 axis triggers autophagy to orchestrate hepatocellular carcinoma radioresistance

Abstract

Radiotherapy (RT) is one of the main therapies for hepatocellular carcinoma (HCC), but its effectiveness has been constrained due to the resistance effect of radiation. Thus, the factors involved in radioresistance are evaluated and the underlying molecular mechanisms are also done. In this present study, we identified Integrin β6 (ITGB6) as a potential radioresistant gene through an integrative analysis of transcriptomic profiles, proteome datasets and survival using HCC cases treated with IR. We show that ITGB6 functionally contributed to radioresistance by activating autophagy through a series of in vitro and in vivo methods, such as clonogenic assays, autophagy flux (LC3B-GFP-mCherry reporter) analysis and a subcutaneous transplantation model. Mechanically, ITGB6 binds to Annexin A2 (ANXA2) and enhanced its stability by competitively antagonizing proteasome mediated ANXA2 degradation, thereby promoting autophagy and radioresistance. Notably, HCC radioresistance was significantly improved by either blocking ITGB6 or autophagy, but the combination was more effective. Importantly, ITGB6/ANXA2 axis triggered autophagic program endowed HCC cells with radioresistant activity in a radiated patient-derived xenograft (PDX) model and hydrodynamic injection in liver-specific Itgb6-knockout mice, further supported by clinical evidence. Together, our data revealed that ITGB6 is a radioresistant gene stabilizing the autophagy regulatory protein ANXA2, providing insights into the biological and potentially clinical significance of ITGB6/ANXA2 axis in radiotherapy planning of HCC.