The Mechanism For Girdin Promoting Tumorigenesis And Chemoresistance In LUAD By Interacting With PKM2

Objective:Lung cancer is the second malignant tumor in terms of incidence and occupies the top mortality worldwide^[1].Lung adenocarcinoma（LUAD）accounts for about 40%of all lung cancer cases,with the characteristic of developing rapidly and metastasizing easily.Patients diagnosed with LUAD are always at late stage,eventually causing poor survival.Girdin is an actin-binding protein^[3].Its roles and mechanisms have been widely studied in transplanted tumor mouse model,but has not been reported in spontaneous tumorigenesis models.In this study,we aim to investigate the role of Girdin in tumorigenesis and chemoresistance.It’s the first for Girdin to be explored in autochthonous mouse model,which has great value to know the bological functions of Girdin in vivo.And classifying the specific mechanism of Girdin in chemoresistance is vital for patients suffered from LUAD to reducing drug resistance when they are treated with chemotherapy.Methods:1.Kras ^LSL-G12D/+;Rosa26^{LSL-Cas9-td Tomato}（KCT）mice were treated via nasal inhalation of Lenti-sg RNAs/Cre to explore the effect of Girdin deletion on autochthonous lung cancer;2.The relevance of Girdin expression and the prognosis of LUAD was analyzed through bioinformatics analysis and immunohistochemistry;Cell proliferation assay was performed by deleting Girdin;3.In metabolomics,Girdin regulated TCA cycle.PKM2 was found as an interacting protein of Girdin by tandem mass spectrometry.4.Girdin regulated the Warburg Effect by reducing PKM2 activity was found through western blot and detection of kinase and metabolites.Results:1.Girdin knockout inhibits LUAD autochthonous tumorigenesis.2.High expression of Girdin is associated with poor survival;and Girdin depletion suppresses cell proliferation in LUAD.3.Girdin interacts with PKM2 and regulates its phosphorylation and activity by inhibiting PDGFRβto modulate the Warburg effect in LUAD.4.Girdin ablation inhibits apoptosis induced by pemetrexed,eventually leading to chemoresistance.Conclusions:Girdin interacts with PKM2 and inhibits its activity to modulate Warburg Effect,leading to chemoresistance in clinical.