Research On The Effect Of Glutamine Synthetase In Adipocytes Influencing The Metastasis Of Colon Cancer Cells

Background and ObjectiveMetastasis is one of the biological features of malignant tumors.There are three common ways of metastasis:lymphatic metastasis,hematogenous metastasis,implantation metastasis.The metabolism of sugar,fat,and amino acid can affect the metastasis of malignant tumors,acting as an important part in the progression of many cancers.The lates t research shows that,glutamine synthetase in adipocytes is able to restrain the metastasis of some malignant tumors,which would become a clinically potential intervention target to restrain the metastasis of cancers.A large number of studies indicate that,sugar and fat can provide essential substantial base for the growth of tumors.As another imperative nutrient in human body,amino acid has very vital function to regulate malignant phenotype of cancer.Glutamine is a common kind of amino acid of human beings,which distributes widely in every organ and tissue,having an indispensably physical role.Glutamine can not only be used to transport the free ammonium ion in the blood by cells,which is called detoxifying,but it can also act as a requisite substance in synthetizing some protein and nucleotide.Glutamine synthetase is the key enzyme regulating the synthesis of glutamine,which is able to catalyze glutamate and ammonium ion into glutamine.Adipocyte is one of the constituents consisting of tumor microenvironment,which has imperative endocrine functions to regulate the malignant phenotype of cancers.Some certain research shows that,tumor cells can take advantage of glutamine to meet their metabolism requirement.Meanwhile,tumor cells are able to regulate the synthesis of nucleotide,thus promoting the generation,progression and metastasis of cancer.However,it is not clear how the metabolism of glutamine in adipocytes influences the progression of malignant tumors.This study is designed to figure out how glutamine in adipocytes regulates hematogenous metastasis of colon cancer by conditional intervention on glutamine metabolism of adipocytes via transgenic GS.Certain cell experiments and xenograft samples are added to further verify our study.Methods1.PCR and Western blot were used to verify the successfully established adiponectin-glutamine synthetase-transgenic(short for Tg^GS)mice at the level of DNA and protein respectively.2.CT26 and MC38 colon cancer cells were separately treated with adipocyte conditional media of Tg^GSS mice and WT mice,CCK-8 assay was applied for the detection of the proliferation of the treated cells,flow cytometry was applied for the detection of the apoptosis of the treated cells,cell scratch assay and Transwell chamber test were applied for the detection of the migration of the treated cells.3.The hematogenous metastasis model was established by tail vein injection in Tg^GSS mice and WT mice separately,HE staining was applied for the detection of the migration and invasion capacity of the liver and lung xenografts.Results1.The Tg^GSS mice had been successfully established.Tg^GSS mice had a much higher level of GS protein expression in adipose tissue than WT mice?n=3,P<0.01?,and there was no difference of GS protein expression among any other important organs and tissues between Tg^GSS mice and WT mice?n=3,P>0.05?.2.CCK-8 assay showed that the two kinds of adipocyte conditional media had no effect on proliferation activity of CT26 and MC38 colon cells?n=5,P>0.05?,and the flow cytometry test illustrated that the two different adipocyte conditional media were barely able to affect the apoptosis rate of CT26 and MC38 colon cells?n=3,P>0.05?.Transwell chamber test and cell scratch assay showed that GS adipocyte conditional media could restrain the migration capacity of CT26 and MC38 colon cells?n=3,P<0.05?.3.There were less lung xenografts in Tg^GSS mice than WT mice?n=3,P<0.05?,and the livers of Tg^GSS mice were lighter than WT mice?n=3,P<0.05?.Conclusion1.Tg^GSS mice have a much higher level of GS protein expression in adipose tissue than WT mice.2.GS adipocyte conditional media have no obvious influence on the proliferation and apoptasis of colon cancer cells.However,GS adipocyte conditional media are able to restrain the migration of colon cancer cells.3.GS in adipocyte is capable of restraining the metastasis of colon cancer cells.