The Study Of Ras Gene Mutation And Expression Of Farnesyltransferase In Primary Liver Cancer

Objective:350thousand people are detected annually in the China to suffer from the PLC (the primary liver cancer) which is a very malignant one. According to a survey conducted by China, the annual death rate of liver cancer in China is roughly10-150/10,000, ranking the third after stomach cancer and oesophagus cancer. The PLC is the chiefly death reason of hepatocirrhosis. It is familiar disease also in the world.320thousand people are die in the China becase of the PLC. At present, the incidence of PLC and its death rate are increasingly high and has become a very serious international health problem. Early diagnose and treatment are important to improve survival rate. But, diagnose way is lower in sensitivity and differential. At present, the AFP albumen is the only diagnostic guideline in serology about the PLC. It is not enough in sensitivity and differential. The pathogeny and mechanism of the PLC is not clarify absolutely. The PLC is a higher death rate' malignant tumor. The chemic and radiative treatment can not achieve the requir of treatment. The diagnose and treatment of gene in the PLC have wider foreground.Tumors are caused by various genetic alterations, including the inactivation of tumor suppressor gene and activation of Proto-oncogenes, etc., and developing as those genetic alterations accumulate. The ras gene mutation widely occurs in solid tumors of human being. It has already found that ras gene mutation occurs in colon cancer, galactophore cancer, bladder caner and stomach cancer, and relates to the staging as well as infiltration and metastasis of some tumors. Research shows that the ras gene can mutate in about30%tumors of human being, in which high expression of ras protein, and the mutated ras protein can cause and develop tumors by promoting cell multiplication and restraining withering of cells. In this research, HotStarTaq PCR was adopted to examine the expression of ras gene in PLC tissues and normal tissues beside the tumor, and the ras gene mutation was analyzed through the method of PCR direct sequencing, in order to find out what role played by ras gene mutation in forming and developing PLC.The famesytransferase (FTase), a heterodimer enzyme in cytoplasm, consists of two subunits, alpha and beta, of which the molecular weight were around48kD and46kD, respectively. It has been confirmed that FTase plays direct roles in cell proliferation, and overexpression of FTase results in altered cell growth and transformation. Further research shows that growth factors of proper quantity, such as insulin-like growth factors-1, platelet derived growth factors, and fibroblast growth factors, can obviously increase the integration of DNA over expressed by FTase and the multiplication of cells. If NIH3T3which is over expressed by FTase is inoculated into nude mouse, then tumors can be caused, but these tumors are different from those tumors which are caused by inoculating cells over expressed by ras into nude mouse; that is to way, FTase plays a direct role in developing and transforming of cells and the development of tumors. Based on the research discussed above, it can be concluded that the fact, that FTase are more active in tumour tissue, indicates the activity of FTase may be the symbol of tumors which may occure; therefore, it might become an index in diagnosis of tumors.Over the past decade, FTase has emerged as a significant target for anti-cancer therapies and become hotspot of anti-cancer research (4). Though inhibitors of the protein famesyltransferase (FTIs) have been developed for cancer chemotherapy, the exactly mechanism remains unknown.This research is to find the relationship between H-ras, N-ras, K-ras gene mutation and primary liver cancer, and what role it plays in developing primary liver cancer. To investigate the Expression of farnesyltransferase(FTase) in primary liver cancer and the role of the development of primary liver cancer.Methods:The cancer tissues are obtained from central part of the carcinomas in32patients who received cancer resection from March,2008to March,2009.20samples. All samples were obtained immediately when tumors were resected, and deep-frozen in-80℃liquid nitrogen. All cancer and normal tissues have been verified by pathological examination. The age of the32patients, including23males and9females in this research is between22and73(57.9±13.4). HBsAg was positive in27and negative in5. Liver cirrhosis was detected in17cases.12patients belonged to Edmondson grade Ⅰ or Ⅱ, and the remaining20patients to Edmondson grade Ⅲ or Ⅳ.14patients belonged to TNM staging Ⅰ or Ⅱ, and18to TNM staging Ⅲ or Ⅳ. According to the operative records and postoperative pathologic data,18patients with cancer emboli, intrahepatic dissemination (satellite foci or multiple nodules) and/or lymph node metastasis were classified as the high tendency to metastatic recurrence group, and the other14patients without emboli, dissemination and/or metastasis belonged to the low tendency to metastatic recurrence group. A total of28patients were followed up for16-30months after the operation, during which time, metastasis or recurrence was found in19patients.The expression of H-ras, N-ras, K-ras gene in primary liver cancer tissues and normal tissues beside the cancer was examined by adopting HotStarTaq, and H-ras, N-ras, K-ras gene mutation was analyzed by PCR direct sequencing method. The Expression of farnesyltransferase were detected by real-time fluorescent quantitative polymerase chain reaction (FQ-PCR) in32cases primary liver cancer and beside nomal liver tissues.Results:The expression of H-ras, N-ras, K-ras gene was detected in primary liver cancer tissues of32patients and their normal tissues beside the caner. After the order of PCR result of32samples of primary liver cancer was examined, H-ras gene in17samples mutated (17/32,53.1%);40condon in14samples mutated from A to G;62condon mutated from G to A in3sample, while no mutation was found in K-ras,N-ras gene and normal tissues beside the cancer. The expression of FTase mRNA in primary liver cancer is significantly higher than that in normal hepatic tissues(P<0.001). The expression of FTase is as high as87.5%. The positive rate for FTase mRNA in high-tendency to metastatic recurrence group was obviously higher than that in low-tendency to metastatic recurrence group (P=0.02). The positive rate for FTase mRNA in patients with metastatic recurrence during postoperative follow-up was also significantly higher than that in those without metastatic recurrence (P=0.01). Conclusions:Abnormal expression of H-ras, N-ras, K-ras gene indicates the alteration of molecule in early stage of liver cancer. It is of possibility that H-ras gene mutation causes primary liver cancer. The level of FTase mRNA expression in primary liver cancer is much higher than that in normal tissues. The FTase may play an important role in the genesis and development of primary liver cancer. This indicates the FTase may directly join in development of primary liver cancer. The FTase plays a direct role in developing and transforming of cells and the development of tumors. Based on the research discussed above, it can be concluded that the fact, that FTase are more active in tumour tissue, indicates the activity of FTase may be the symbol of tumors which may occure; therefore, it might become an index in diagnosis of tumors. FTase may play an important role in the genesis and development of PLC and may be one of the reliable markers for the metastatic activity gained by the liver tumor cells and could be used clinically in predicting metastatic recurrence of PLC. FTase overexpression might provide a potential and valuable index to predict clinically postoperative metastatic recurrence.