Liver Cancer Prevention, Early Diagnosis And The Pathogenesis Of Three Related Issues

This paper contains three sections. The molecular mechanism of HCCcarcinogenesis and metastasis were studied on perspectives of prevention, diagnosisand basic medical research. The first part focuses on the escapism of vaccine in theHBV prevention of Qidong Area, it analyses several possible reasons and points outthat the point mutation of "a" epitope in HBV S gene is one of the main reasons. Also,it indicates the importance of elimination mutations in vaccine prevention. The secondpart examines the mutation occurs to 249 codon of 7th exon in P53 which isdisseminated in different patients suffering from liver diseases. Besides, it points outthat the molecular marker could be a new diagnostic marker for verifying liver cancerin early phase. The third part investigate the basic function of RTN4B and RTN4C,which are abnormally expressed in HCC( Human Hepatocellular Carcinoma). Itreveals that the RTN4B protein , not only could be a molecular marker for HCCpathological diagnosis, but also could act as a linkage in a new pathway which isrelated to hepatocarcinogenesis. 1. Hepatitis B virus (HBV) infection is the main factor, which induceshepatocellular carcinoma (HCC) in Qidong high-risk area. To prevent HBV infectionis the most important strategy to inhibit the HCC carcinogenesis. A large project wasperformed in Qidong area to protect newborn babies from the HBV infection that80,000 children born between 1984 and 1990 were vaccinated. After three times offollow up studies, 15 screened children were found to have symptoms of illnessshowing persistent elevating of serum glutamic-pyruvic transaminase (ALT). The ALTlevels of 5 vaccinees with negative hepatitis B surface antigen (HBsAg) weresignificantly higher than those of 10 vaccinees with positive HBsAg. We collectedblood samples from 15 screened vaccinees, and isolated HBV genome DNA fromthese sera. Primers were designed and the HBsAg coding sequences were cloned.Sequencing results showed that compared with HBV wild type, the HBsAg "a"epitope coding sequences of 5 vaccinees with negative HBsAg were found to havedifferent point mutations at nucleotide position 530,540,544,558,560,561,587(numbered from the EcoRI site of HBV genome) that resulted in amino acidsubstitutions at 126,129,135,136,145 from the start of HBsAg. We found that of the 7point mutations, 6 were detected in the coding sequences of the first loop structure in"a" epitope, and 1 was detected in the coding sequence of the second loop structure. 4amino acid substitutions were occurred in "a" epitope at corresponding position 11复旦大学博士学位论文 前言126,129,135,136, and only 1 amino acid substitution was found at amino acid position145, which is the most popular mutant (glycine → arginine). The structure of doubleloop conformation in "a" epitope was conservative, and important for HBVantigenicity. These changes in a double loop conformation would escapeneutralization by vaccine-induced antibody. 2. One of the characteristics of hepatocellular carcinoma (HCC) in Qidong areais the selective mutation resulting in a serine substitution at codon 249 of the p53gene, and it has been identified as a "hotspot" mutation in heptocellular carcinomasoccurring in populations exposed to aflatoxin and with high prevalence of hepatitis Bvirus carriers. We evaluated in this paper whether this "hotspot" mutation could bedetected in cell-free DNA circulating in plasma of patients with hepatocellularcarcinoma and cirrhosis in Qidong, China, and tried to illustrate the significance ofthe detection of this molecular biomarker. We collected blood samples from 25 hepatocellular carcinoma patients, 20cirrhotic patients and 30 healthy controls in Qidong area .DNA was extracted andpurified from 200μl of plasma from each sample. The 249Ser p53 mutatio...