Experimental Study On Treatment Of Human Gastric Cancer Cell With Combination Of Docetaxel And FHIT

【Background and Objective】Gastric cancer is one of the most frequent malignant tumors in human beings.In addition,the morbidity and mortality of gastric cancer is highest in China.Most cases are at midst or advanced stage until recieved a final diagnosis.The 5-year survival rate of gastric cancer is only about 20%-30%after a surgery operational therapy.Its prognosis has not been satisfactoried jet.These years,the therapy of gastric cancer has been developed greatly;however,its treating effect is very poor.Surgical resection can not get rid of all of cancer cells and has the potential possibility of recidivation and transferred.Therefore,gene therapy for gastric cancer is a very important adjunctive therapy method for surgery,radiotherapy and chemotherapy.Some factors,such as proto-oncogene activation,anti-oncogene inactivation and reparation gene mismatching,has been thought to take a key role for the process of tumorigenesis.To conquer cancer thoroughly,many studies about oncogene are being performed,therefore,proto-oncogene activation,anti-oncogene inactivation and reparation gene mismatching have been found.Fragile histidine triad(FHIT) gene, which is located in chromosomal region 3p14.2,has been cloned by Ohta et al in 1996. It spans not only the t(3:8)(p14.2;q24) translocation breakpoint found in familial renal cell carcinoma,but also the most common human fragile site,FRA3B.It is subordinated to histidine triad(HIT) protein superfamily.FHIT has been recently proposed as a tumor suppressor gene.Although there was some doubt about its antitumous effect,more and more studies have revealed that FHIT is an anti-oncogene. The mechanism of this anti-oncogene is not very clear.Several pathways may be associated with its anti-cancer effect.It is found that FHIT has a close correlation with cancers(such as gastric cancer) which are associated with environment carcinogenic agents,and its expression deletion and abnormality rate are high.FHIT has been transfected into tumour cells and expressed well,which can reverse some malignant phenotypes of the tumour cells.In addition,it can also induce tumor apoptosis,which can cure tumor or enhance the traditional therapy.FHIT has also been studied for its effect on chemistry drug sensitivity.As a stabilizer of microtubule,Docetaxel is important in the therapy of gastric cancer.The effective rate of late gastric cancer treated with Docetaxel is about 17%-24%.Based on the good activity of Docetaxel and the effect of FHIT in gastric cancer,we used two factors to treate the human gastric cancer cell line,MGC-803,which has a absence expression of FHIT.And to investigate the effect of exogenous FHIT on the apoptotis of gastric cancer cells induced by Docetaxel,which provide the rationale for the combined treatment of gene and chemical for gastric cancer.It's not reported in China.【Methods】At different concentrations(1.0,5.0,10,20,40μg/ml) and different time(24h,48h,72h),Methyl thiazolyl tetrazolium(MTT) assay was used to measure the inhibition ratio of gastric cancer cell MGC-803 treated by Docetaxel,and chose the best concentration and time.The recombination eukaryotic expression plasmid with exogenous FHIT was transfected into MGC-803 by liposome.Flow cytometry was employed to detect the apoptosis ratio of gastric cancer cell treated by FHIT and DOC. And the proteinum expression of cleaved-Caspase3 was measured by Western blot.【Results】1.Stable expression of FHIT protein in transfected MGC-803 cells was obtained.2.DOC had inhibitory effect,which is the most obviously at 20μg/mL and 48h, to gastric cancer cell.3.The apoptosis ratio in DOC combined with pRcCMV-FHIT group(65.54%) was significantly higher than that in control group(3.27%),pRcCMV group(3.55%), pRcCMV-FHIT group(13.94%),DOC group(44.13%),DOC and pRcCMV group (45.29%) respectively(P＜0.05).4.Cleaved-Caspase3proteinum expression in DOC+ pRcCMV-FHIT group was significantly higher than any other group.【Conclusions】FHIT expression and DOC could promote the apoptosis of gastric cancer cell synergistically,which may be a result of the up-regulation of Caspase3 proteinum expression induced by FHIT expression and DOC synergistically.