SIRPG Plays A Role In Acquired Resistance To Gefitinib In Non-small Cell Lung Cancer

Research Background and Objectives: Lung cancer is one of the malignant tumors with the highest incidence and mortality rates in the world,with a 5-year survival rate of only 16.8%.In 2015,there were 733,000 new cases and 610,000 deaths from lung cancer in China,with both incidence and mortality rates ranking first among all malignant tumors.Non-small cell lung cancer(NSCLC)accounts for about 85% of all pathological types of lung cancer,with about 70% of patients diagnosed at an advanced stage and having lost the opportunity for surgical treatment.Currently,Epidermal Growth Factor ReceptorTyrosine Kinase Inhibitor(EGFR-TKI)gefitinib is a first-line treatment for NSCLC patients with EGFR sensitive mutations,with significant clinical efficacy.However,the development of acquired resistance is inevitable and its mechanism has not been fully elucidated.The target protein encoded by the molecular studied in this research,SIRPG,is a member of the signal-regulatory protein(SIRP)family and also belongs to the immunoglobulin superfamily.SIRP family members are receptor-type transmembrane glycoproteins that are known to be involved in the negative regulation of receptor tyrosine kinase-coupled signal transduction.Signal-regulatory protein γ(SIRPγ)is a member of three closely related families of cell surface receptors,and is involved in the regulation of immune/inflammatory responses.However,the mechanism of its role in tumor resistance is not clear.This project aims to study the mechanism of the impact of knocking down SIRPG on gefitinib acquired resistance in NSCLC.Research Methods: In this study,PC9 and PC9 GR cells were purchased from the Shanghai Institute of Cell Biology,and their drug resistance was tested using CCK8.Transcriptional profiling was performed on PC9 and PC9 GR cells,and target gene SIRPG was screened through bioinformatics analysis and CCK8 and q RT-PCR.Then,by constructing a SIRPG knockdown lentivirus vector and stably transfecting PC9 and PC9 GR cells,a series of cellular biology experiments were carried out to verify the in vivo impact of this gene on acquired resistance of NSCLC to gefitinib.To investigate the role of SIRPG in vitro in NSCLC acquired resistance to gefitinib,a subcutaneous tumor model was established in nude mice,and the proliferation and apoptosis of the tumor were detected by immunohistochemistry and TUNEL experiments.Finally,q RT-PCR and Western blot were used to detect changes in the expression of key proteins in related pathways to reveal the molecular mechanism of SIRPG in NSCLC acquired resistance to gefitinib.Research Results: 1.CCK8 testing of PC9 and PC9 GR cell viability showed that PC9 GR resistance was stable and met experimental requirements.2.Throug transcriptional profiling,bioinformatics analysis,q RT-PCR,and Western blot verification,target gene SIRPG was screened.3.After SIRPG knockdown by lentivirus infection in PC9 and PC9 GR cells,cell growth was inhibited,the cell cycle was blocked in the G1/S phase,and cell apoptosis was induced.4.In the nude mouse subcutaneous tumor model,knocking down SIRPG could inhibit tumor growth and promote tumor apoptosis,with consistent results in in vivo and in vitro experiments.5.q RT-PCR and Western blot experiments showed that after knocking down SIRPG,the protein expression levels of P53,PTEN,and TNF-α increased,while the protein expression levels of CCNB1 and CCND1 decreased.Research Conclusion: SIRPG plays an important role in the occurrence and development of acquired resistance to gefitinib in NSCLC cells and may serve as a potential intervention target for the treatment of NSCLC resistance.