Role And Molecular Mechanism Of S100A4 On Non-Small-Cell Lung Tumor Growth And Obesity

Lung cancer represents one of the most frequently malignant diseases over the world.The latest statistical results show that the mortality rate of lung cancer ranks the first among malignant tumors,while the incidence and mortality of lung cancer are still rising.According to the differences of histological types,lung cancer can be divided into two types,small-cell lung cancer(SCLC)and non-small-cell lung cancer(NSCLC).NSCLC accounts for more than 85%in lung cancer cases,with poor prognosis and low 5 year survival rate.Autophagy plays an important role in sustaining cellular homeostasis.In recent years,autophagy has been found to regulate a variety of physiological and pathological processes,including ontogenesis,cellular senescence,inflammation,immune response and tumor development in organisms.The abnormal autophagy activity in the body is closely related to the development of a variety of malignant tumors,including lung cancer.S100A4 is a calcium binding protein from S100 family,which is mainly expressed in fibroblasts,macrophages and some malignant tumor cells.Many studies have shown that S100A4 plays an important role in tumor invasion and metastasis.We have studied the role of S100A4 in tumorigenesis and development in our previous observations.It has been found that S100A4+ cells can promote the development of skin carcinoma by recruiting macrophages and promote the development of colon cancer by activating the nuclear factor-kappaB(NF-κB)signaling pathway in macrophages.However,it is not clear whether S100A4 can affect the progression of tumor by participating in autophagy regulation.There is a significant correlation between obesity and the development of a variety of tumors,but the relationship between obesity and lung cancer,especially non-small cell lung cancer,has not been well demonstrated.Based on the preliminary study of the role and molecular mechanism of S100A4 in non-small cell lung cancer,the role of S100A4 in obesity was further researched in this study,which provides the basis research for the next step while exploring the relationship between S100A4,lung cancer and obesity.The research in this paper is part of the complex biological system and is an important supplement to the research of the whole system theory.The first part of this study used the biological data obtained from clinical lung cancer specimens to analyze the correlation between S100A4 expression and the progression of lung cancer through Spearman’s correlation coefficient,which is an important statistical analysis method in clinical.Using S100A4 knockout mice,a transplanted tumor model was established and the differences between the normal group and the gene knockout group were analyzed by t test.Combined with analysing multiple groups of data from experiments of lung cancer cells in vitro through one-way analysis of variance method,we explored the role and molecular mechnism of S100A4 in the regulation of autophagy and the development of lung cancer.This study showed that S100A4 can inhibit autophagy and promote the development of non-small cell lung cancer through β-Catenin signaling in a S100A4 protein receptor-Receptor for Advanced Glycation End products(RAGE)dependent manner.In the second part of this study,we used S100A4 gene knockout mice and obese mice induced by high fat diet(HFD)as models and combined with in vitro experiments to study the role and molecular mechanism of S100A4 in obesity.We found that S100A4 could inhibit high fat induced obesity and inflammatory response by activating the Akt signaling pathway.The first part’s innovative and main work are as follows:1.Using clinical lung cancer specimens,we analyzed the correlation between S100A4 and progression of lung cancer.Through Spearman’s correlation coefficient,we found that the expression of S100A4 protein was significantly up-regulated in human lung adenocarcinoma tissues,and its expression was positively correlated with tumor size and tumor grade.2.In the transplanted lung tumor model,we studied the role of S100A4 in the development of lung cancer and its regulation function on autophagy.Through t test we found that the growth of transplanted tumor was significantly slower in S100A4 knockout mice.S100A4 can inhibit autophagy in tumor tissues and promote the growth of lung cancer by activating the β-Catenin pathway.3.In combination with in vitro experiments,we explored the molecular mechanism of S100A4 affecting autophagy and tumor development.Through one-way analysis of variance we found that both exogenous protein and intracellular overexpression of S100A4 can inhibit the autophagy induced by starvation and promote the proliferation of tumor cells;S100A4 inhibited autophagy by activating β-Catenin signaling pathway and thus promoted survival and proliferation of lung tumor cells.After the β-Catenin signaling pathway was blocked,the inhibition effect of S100A4 on autophagy in tumor cells was obviously diminished;The inhibitory effect of S100A4 on autophagy in tumor cells is RAGE receptor dependent;After blocking the RAGE receptor,both the inhibition effect of S100A4 on autophagy and the promoting role of S100A4 on proliferation of lung cancer cells A549 and LLC were abolished.The second part’s innovative and main work are as follows:1.S100A4 was expressed in adipose tissue stromal cells,t test revealed that S100A4 protein was decreased in high fat induced obesity model.2.S100A4 derived from mesenchymal cells in adipose tissue can inhibit HFD induced obesity.In t test,after the induction of high fat diet,the S100A4 knockout mice were more obese compared with the control group.The fat deposit in the liver and the inflammatory reaction of S100A4 knockout mice were increased while the contents of cholesterol and triglycerides in the serum of S100A4 knockout mice were increased significantly.3.Using the 3T3-L1 preadipocytes,after one-way analysis of variance,we found that the expression of inflammatory factors and adipogenic factors were downregulated by S100A4 through activating the intracellular insulin related pathway Akt after extracellular S100A4 protein stimulation as well as intracellular overexpression and knockdown of S100A4.To sum up,using a variety of mathematical statistics methods,this study found that S100A4 can inhibit autophagy and promote the progression of non-small cell lung cancer by means of β-Catenin signaling in a S100A4 protein receptor-RAGE dependent way.These findings revealed that S100A4 plays an important role in the progression of cancer and will also provide a new reference for the development of new tumor treatment drugs.In addition,S100A4 displayed a protective role in obesity,which was manifested by the inhibition of fatty formation and inflammation in the liver and adipocytes,suggesting that S100A4 can be applied to the development of therapeutic agents for obesity and metabolic syndrome(fatty liver,diabetes,etc.).