Aberrance Of Fragile Histidine Triad Gene In Patients With Lung Cancer

The incidence of malignant tumor is increasing and the onset age is tending to be younger along with the changes of environment and life-tyle of human being. Lung cancer is a common malignant tumor, the increasing of lung cancer is in the first place. Tumorgenesis of lung cancer is related to multiple gene abnormalities, such as p53, ras, c-fos, c-jun, et al. In 1996,Ohta discovered a new gene-FHIT(fragile histidine triad FHIT)by exon- capture technique. Abnormal FHIT has usually been found in various epithelial cancers. It was reported that this genewas closely associated with the environmental carcinogen. FHIT gene is a focus for the study of environmental carcinogen acted upon.Human FHIT gene, a member of the HIT gene family, spans about 500Kb. It encodes 1.1Kb mRNA, including 10 exons, and exon 5 to 9 is encoding domain of HIT.FHIT gene is located at 3p142, it overlaps with FRA3B,which is the most common fragile site in human chromosome. Fhit protein is consisted of 147 amino acids weighted 16.8Kb. The core of Fhit shows similarity to diadenosine 5',5 -p1,-p4-tetraphosphate(AP4A)hydrolase from the fission yeast Schizosaecharomycespombe. The Fhit from humans is classified as an dinucleoside 5 -5 -p'-p3-triphos-phate(AP3A)hydrolase, it plays a role in cell differentiation and apoptosis by the ratio of AP3A/AP4A. It was reported that Fhit could strengthen cell s endurance to carcinogens:FHIT gene differs from the classical suppressor gene, abnormalities at transcript level were deletion of one or several exohs, sometimes were insertions, but up to now, point mutation has not been found. In this study, DNA fragment of FHIT was analyzed by using PCR-SSCP andDNA sequencing. The purpose of this study is to provide useful information for mutation in plasm DNA and prewarning of lung cancer. MethodsGenomic DNA was isolated from lung cancer tissues, no-tumorous lung tissues, and benign. Specific primers of FHIT gene exon 5 were designed by using DNAClub and OMIGA software. Polymerase Chain Reaction was used to amplify the target gene PCR-SSCP and silver staining were used to find abnormalities. The positive samples were sequenced by dideoxy method with DNAs sequencer. ResultsAmong 6 of 21 lung squamous cell carcinoma, one of 6 lung adenocarcinomas expressed aberrant FHIT gene. The others were normal. There was significant difference between the group of tumors and the group of non-tumor (p<0.05). There were no significant differences among the different histological types.Seqencing analysis of the altered sample showed that two base pairs were detected to be different from the sequence of GeneBank in two samples. (G inserted after position 188,T toC in position 227). Conclusions1. Aberration of FHIT gene in DNA was associated with lung cancer, it may not be associated with the patient's histological types.2. Mutation in introns of FHIT gene may be one of the reasons altering RNA splicing.