The Protein Stability Regulation Of EGFR Mediated By Hedgehog/PTCH1 Signaling And Its Function In NSCLC

Background:Lung cancer is one of the most common malignant tumors in the world.It is also the most common cancer with the highest morbidity and mortality in China.Non-small cell lung cancer(NSCLC)is an important type of lung cancer,mainly including lung squamous cell carcinoma and lung adenocarcinoma.The epidermal growth factor receptor(EGFR)encoded by ErbB-1 gene plays a very important role in the occurrence and development of NSCLC:EGFR mutation can be detected in 40%of lung adenocarcinoma specimen,EGFR gene amplification and increased expression were found in 30%of lung squamous cell carcinoma specimen,suggesting that EGFR may be one of the key driver genes of lung cancer.Hedgehog(Hh)signaling pathway is an important signaling pathway regulating the organism development,and Hh signaling disorder is closely related to the occurrence and development of various tumors and drug resistance.It has been reported that Hh signal and EGFR signal pathway have a synergistic effect on the development of tumor.Animal experiments and clinical trials have found that Hh signal inhibitor combined with EGFR inhibitor can effectively inhibit tumor growth,indicating that Hh signal and EGFR signal have synergistic effect and interactive regulation,but the detailed molecular mechanism remains to be studied.Objective:Our study will start with the regulation of Hh/PTCH1 signal on the stability and activity of EGFR protein,explore the regulation mechanism of Hh signal and EGFR signal at the receptor aspect,and establish a new Hh/PTCH1/EGFR signal axis.1.Clarify the regulatory effect of Hh/PTCH1 signal on EGFR protein stability and activity;2.Explore the mechanism of Hh/PTCH1 regulating the stability and activity of EGFR protein;3.Discuss the physiological significance of Hh/PTCH1/EGFR signaling axis in non-small cell lung cancer.Methods:1.PTCH1 was overexpressed in 293T cells to observe its role in the expression of EGFR/HER2 protein,detect the mRNA level of EGFR/HER2,and verify whether it is regulated by transcription.Cells were treated with proteasome inhibitor or lysosome inhibitor to study the EGFR/HER2 degradation pathway.Exogenous Shh and EGF stimulated cells to detect the effect of PTCH on the stability and activity of EGFR protein.2.The interaction between PTCH and EGFR/HER2 and the EGFR ubiquitination were detected by immunoprecipitation,and the EGFR segmented plasmid was constructed to study the interaction mechanism between PTCH and EGFR.3.PTCH overexpression in lung adenocarcinoma cells,and observe the expression of EGFR/HER2 protein,and the expression of EGFR and PTCH were detected in clinical tissue specimen of lung squamous cell carcinoma.Results:1.PTCH 1 can interact with EGFR/HER2,and Hh ligand can induce PTCH1 to regulate the stability and activity of EGFR/HER2 protein.2.PTCH1 mediates ubiquitination of EGFR and promotes lysosomal degradation of EGFR;3.The co-effect of Shh and PTCH1 in lung cancer cells can promote the degradation of EGFR,and the expression of EGFR and PTCH1 is opposite in lung cancer tissue specimen.Conclusion:PTCH 1 interacts with EGFR/HER2.In the presence of Hh ligands,PTCH1 mediates ubiquitination of EGFR and promotes lysosomal degradation of EGFR/HER2.This process may play an important role in non-small cell lung cancer cells.