Effects Of GDF15 On The Bone Metastases Of Non-small Cell Lung Cancer And Its Mechanism

BackgroundLung cancer ranks first in annual incidence and deaths among Chinese population.The pathological type is mainly non-small cell lung cancer(NSCLC),with a high degree of malignancy and often metastasis to bone in the late stage.As a member of the TGF-? superfamily,growth differentiation factor 15(GDF15)has been verified to be involved in many types of malignancies and numerous pathological processes in the body.However,the role of this gene in lung cancer remains controversial.It plays different roles in different stages of tumors and tumors of different pathological types,sometimes even to the contrary,and its function in bone metastases of NSCLC is seldomly reported.In order to clarify the facts,this study will use a series of in vitro and in vivo experiments in NSCLC to validate and explore its role in bone metastases preliminary.PurposeApplied the whole-genome sequencing techniques,we screened the genes related to NSCLC and its bone metastases.Through the experiments in vivo and in vitro,the cell model was used to observe the proliferation,migration,invasion and apoptosis of non-small cell lung cancer A549.With the employment of animal models,we explore GDF15's role in bone metastases of NSCLC.The purposes of above experiments are to find a new target for the prevention and treatment of lung cancer and bone metastases,meanwhile,to provide the theoretical basis for it.Methods1)Using the database of lung cancer bone metastases and lung cancer patients established by our department,two groups of patients with lung adenocarcinoma were selected,which were bone-metastases group and non-bone metastases respectively.The DNA of two groups lung cancer specimens were extracted and then sent to the company to conduct whole-genome sequencing.The differences between the two groups of SNPs were screened in lung cancer database and metastases-related database for further screening,and further screening of genes related to bone metastases of lung cancer through gene database and literature;2)A549 cell line with high expression of GDF15 was constructed by plasmid transfection.The cell biological function was observed by MTT assay,colony-forming assay,transwell based methods and apoptosis assay;3)A549 cell line with high expression of GDF15 was established by lentivirus infection.The metastatic tumor model of NOD/SCID mice was established by tail vein injection;4)By observing the growth of lung tumors in two groups of mice,we deduced the relationship between GDF15 and tumor development in vivo;5)The effect of GDF15 on bone metastases of A549 cells was evaluated by X-ray examination and luciferase assay;6)Preliminary exploration of GDF15 in lung cancer and its bone metastases-related pathways.Results1)By whole-genome sequencing technique,combined with lung cancer database and metastases related database,240 differential genes were screened out.With further research of gene datebase such as Genecards,NCBI,cBioPortal and Pubmed,GDF15 was found that may be associated with lung cancer and its bone metastases;2)In cell experiments,GDF15 can significantly inhibit the proliferation,migration and invasion of A549 cells and promote apoptosis;3)Successful construction of A549-GDF15 and A549-NC cell lines,construction of lung cancer bone metastases mouse model,were applied to follow-up experiments;4)GDF15 inhibits the growth of A549 cells in vivo too;5)GDF15 inhibits the formation of bone metastases in A549 cells in NOD/SCID mice;6)GDF15 may inhibit the growth of lung cancer and bone metastases through Smad pathways.ConclusionsGDF15 is one of the candidate molecules that may be related to bone metastases of lung cancer,which is screened from the tissue samples of patients with bone metastases of lung cancer through whole-genome sequencing from the genomics level.In this experiment,we found that GDF15 can effectively inhibit the proliferation,migration and invasion of human lung adenocarcinoma A549 cells in vitro and promote apoptosis.In vivo,GDF15 can inhibit the formation of bone metastases in mice,and the number of its lung tumors is smaller and the weight is lighter.This is consistent with the results of in vitro experiments on the inhibition of tumor cells: GDF15 can inhibit the growth,migration and bone metastases of NSCLC cells and may play this role through Smad pathway.This discovery of lung cancer and bone metastases of its clinical prevention and treatment can provide a new target and theoretical basis.