Function And Molecular Mechanism Of Skeletal Proteins MYH9 And Palladin In The Development Of Lung Cancer

Lung cancer is one of the diseases with the highest mortality rate,its prevention and control mechanism has been widely concerned.Lung cancer,as one of the malignant tumors in the world,has been listed as the focus of cancer prevention and treatment.Due to its high specificity and mild side effects,targeted therapy has gradually attracted people's attention.However,the presence of cancer stem cells has gradually reduced or even nullified the efficacy of many existing targeted drugs,making targeted therapy face great challenges.Therefore,the identification for new therapeutic targets for lung cancer and its stem cells can bring more breakthroughs for clinical treatment.Skeletal proteins have important biological characteristics and functions.In-depth study of skeleton related proteins can provide new strategies for the prevention and treatment of tumors.In the previous study,the team found that the skeleton proteins MYH9 and Palladin are highly expressed in lung cancer,suggesting that these two proteins may have some association with the progression of the malignant phenotype of lung cancer.Subsequently,we used lung cancer cells,clinical pathological specimens and animal models to conduct in-depth studies on the two proteins through in vivo and in vitro biological function experiments,hoping to find new therapeutic targets for lung cancer.In the study of MYH9,immunohistochemical experiment results showed that MYH9 was highly expressed in clinical samples of non-small cell lung cancer and the expression of MYH9 in the cell membrane and nucleus were specific for cancer tissue,and the expression of MYH9 in different parts was positively correlated with poor clinical prognosis of patients.Multivariate linear regression also found that MYH9 can be used as an independent factor in the prognosis evaluation of patients with non-small cell lung cancer.Chi-square test results show that MYH9 is significantly associated with the patient's survival and prognosis,as well as the patient's gender and clinical stage.Subsequent in vitro and in vivo experiments showed that after overexpression of MYH9,the proliferation of lung cancer cells in vitro and in vivo,migration and invasion,self-renewal ability and drug resistance were significantly enhanced,and the expression of some marker proteins related to cell phenotype was also observed and corresponding changes have taken place,and in the low-expression cell line of MYH9,these malignant features of lung cancer cells are attenuated.Therapeutic experiments with the MYH9 inhibitor blebbistatin have also shown that blebbistatin can inhibit the growth of lung cancer cells in vivo.Through further mechanism studies,MYH9 can activate the mTOR signaling pathway.The sphere-forming culture experiments performed on lung cancer cells with the specific inhibitor of mTOR protein Rapamycin and GSK3?/? inhibitor(CHIR-99021)further confirmed that MYH9 functions in vitro by activating the mTOR signaling pathway.In the study of Palladin,immunohistochemistry results showed that Palladin is highly expressed in clinical samples of non-small cell lung cancer and its expression in the cell membrane is specific for cancer tissues,but only Palladin s cytoplasm expression and the clinical prognosis of patients were positively correlated,Multivariate linear regression found that Palladin could not be used as an independent index to judge the survival prognosis of patients with non-small cell lung cancer.The results of chi-square test indicated that Palladin was significantly correlated with gender of patients in addition to survival and prognosis of patients.The biological function experiments showed that after the expression of Palladin was up-regulated,the malignant characteristics(in vitro and in vivo proliferation ability,migration and invasion ability,self-renewal ability and drug resistance)of lung cancer cells were significantly enhanced,and the expression of some marker proteins related to cell phenotype was also observed and corresponding changes have taken place,and in the cell line of Palladin knockdown,changes in lung cancer cell capacity and changes in marker protein expression were reversed.Through further research on molecular mechanisms,Palladin can activate the classical Wnt signaling pathway.Experiments with Wnt-C59,a specific inhibitor of p-catenin,further confirmed that Palladin can activate the Wnt/p-catenin signaling pathway.Finally,we studied the combined effect of MYH9 and Palladin,and the results showed that the proliferation,migration,invasion,drug resistance and self-renewal ability of both MYH9 and Palladin knocked down lung cancer cells were weaker than those knocked down by MYH9 or Palladin alone.In conclusion,as oncogenes,MYH9 and Palladin can evaluate the survival prognosis of patients with non-small cell lung cancer,promote the development of malignant phenotype of lung cancer cells and may be new therapeutic targets for lung cancer and lung cancer stem cells.The combination of MYH9 and Palladin has a greater impact on lung cancer cells than their individual effects,providing new insights into multi-target combination therapy for cancer.