Preliminary Study On The Effect Of Adipocytes On The Biological Behaviors Of Lung Adenocarcinoma A549 Cells In Tumor Microenvironment

Background and objectiveLung cancer is the most common cause of cancer-related deaths worldwide and is associated with more morbidity and mortality than other malignancies.The 5-year relative mortality rate in adenocarcinoma cases is very high,ranging from 51% to 99% due to the presence of metastasis at the time of diagnosis.Studies of relative risk factors and a deeper understanding of the pathogenesis of adenocarcinomas are important for prevention and improved targeted treatment.Adipocytes in the tumor microenvironment may provide the metabolic fuel or signal transduction through media and other means to promote a variety of malignant proliferation and invasion,of tumor cells,but their role in lung cancer progression is still unclear.The purpose of this study was to investigate the effect of adipocytes on lung cancer cell biology.Methods1.Induction of 3T3-L1 pre-adipocytes into mature adipocytes according to the classical "cocktail" method.2.Indirect co-culture model of Transwell was used to indirectly co-culture 3T3-L1 pre-adipocytes and mature adipocytes with A549 lung adenocarcinoma cells.3.The cell morphology was observed by microscopy and Oil Red O staining.4.MTT assay,colony formation assay were used to detect lung cancer cell proliferation.5.Wound-healing and Transwell methods were used to detect lung cancer cell migration and invasion ability.6.The protein expression of EMT in lung adenocarcinoma A549 was detected by Western Blot.7.The contents of triglyceride,free fatty acids in the cytoplasm of adipocytes,the content of triglyceride in cytoplasm,glucose uptake rate and lactate secretion rate of lung adenocarcinoma A549 cells were detected by colorimetric assay.Results:1.3T3-L1 pre-adipocytes were induced into mature adipocytes.After co-culture with mature adipocytes,and the proliferation and cloning ability were significantly enhanced(P<0.05).2.The morphology of lung adenocarcinoma A549 cells became more slender after co-culture with mature adipocytes,EMT-related protein E-cadherin levels decreased,vimentin levels increased.3.Mature adipocytes can significantly promote the lateral migration ability(P<0.05),longitudinal migration ability(*P <0.01)and invasion ability(P<0.01)of A549 cells.4.Mature adipocytes,which were indirectly co-cultivated with lung cancer cells for a prolonged period,exhibited a dramatic reduction in the number and size of lipid droplets.Meanwhile,we observed a significant reduction in adipocyte TG content following co-culture with lung cancer cells(P < 0.05).In addition,in the presence of lung cancer cells,adipocytes released significantly more free fatty acids than adipocytes cultured alone(P < 0.001).5.After co-cultured with mature adipocytes,the intracellular lipid of lung adenocarcinoma A549 cells were significantly accumulated(P <0.05),glucose uptake rate(P <0.05)and lactate production rate(P <0.01)increased significantly.ConclusionThese findings suggested that adipocytes in tumor microenvironment can promote the proliferation,migration and invasion of lung adenocarcinoma A549 cells,which may be related to metabolism.The present study highlight the potential for characterization of adipocyte–cancer cell interactions not only to provide a better understanding of the progression of lung cancer but also to identify avenues for the development of new therapeutic strategies.