DcR3 Expression In HCC And Its Value In Suppressing Fas-induced Apoptosis And Chemotaxis

DcR3 (also known as TR6 and M68), a new member of the TNF receptor (TNFR) family, has been identified by Pitti et al in 1998. It maps to chromosome position 20ql3.3. DcR3 is a soluble decoy receptor for FasL,which lacks a transmembrance domain and is secreted into the extracellular space. DcR3 binds to the FasL and LIGHT, thereby neutralizing their proapoptotic action. It has been demonstrated that DcR3 frequently is overexpressed in malignant tumors arising from lung, gastrointestinal tract and et al. The DcR3 overexpression exists only in tumor tissues. Moreover, Pitti et al detected a high percentage of DcR3 gene amplifications in colon and lung carcinoma. Thus it has been postulated that Fas/FasL interactions might limit cancer growth and that cells expressing high levels of DcR3 are more likely to escape elimination via the Fas/FasL pathway. Apoptosis is known to be very important in tumor biogressiveness. A lot of strages for treatment of tumor are based on involving the mechanism of apoptosis. To treat tumor via inducing apoptosis is more and more improtant, and is going to be a powerful weapon which is used to conquer tumor by people.The function of DcR3 in immune evasion remind us, if the DcR3 expression can be suppressed in the level of gene or protein, then the treatment of tumor will be improved, moreover we can stop the information and recurrence of tumor. DcR3 is a soluble protein, thus detecting DcR3 protein level in blood may be a valuable diagnostic method for the tumor with positive DcR3 protein expression. We have already done one pilot investion for serum level of DcR3 protein in many kind of tumors. We find that the level of DcR3 protein in peripheral blood is significantly higher in patients with HCC than in healthy people. Compare with the healthy people, some patients with HCC have a 20-fold DcR3 protein level. But untilnow, there are no research on the DcR3 expression and genomic amplification in HCC, on the relationship between the DcR3 expression and apoptosis of HCC.In this study, the mRNA expression and genomic amplification of DcR3 in HCC were investigated , the values of DcR3 overexpression in suppressing FasL-induced apoptosis and chemotaxis was analyzed. This study is aimed at investigating the antiapoptosis mechanism of HCC. The result of this study will be a fundamental in treatment of HCC via the way inducing apoptosis.Part I: The overexpression and genomic amplification of DcR3 and its significance Objective:To study the mRNA expression and genomic amplification of DcR3 in HCC, toanalyze the mechanism of DcR3 overexpression.Methods: 48 cases of HCC, which has been proved by operation and pathology, is studied. Detecting the DcR3 mRNA in the cancer tissues and the normal tissues adjacent to the tumor with RT-PCR, quantifing the DcR3 gene amplification in the cancer tissues by quantitative genomic PCR, examining DcRJ protein expression in the tumor tissues of HCC by SABC immunohistochemistry (IHC).To analyze the relationship between the DcR3 mRNA expression and genomic amplification of HCC with statistic methods, to compare the difference of DcR3 expression and amplification in the HCC with different clinical and pathological feature.Results: DcR3 mRNA was detected in 29 cases out of total 48 case HCC, the ratio of positive expression is 60.4%(29/48). No positive mRNA expression was detected in 48 normal tissues adjacent to the tumor. DcR3 mRNA expression in HCC show a relationship with the size of mass, the clinical stage and the metastasis of the tumor(P<0.05)J but no relationship with the membrane of the tumor, cancer embolus, and the number of mass. The DcR3 gene amplification in 48 cases of HCC ranges from 0.18 to 3.86-fold. 7 of 48 cases HCC show significantly higher DcR3 gene amplification than the normal control tissues. Compare the DcR3 mRNA expression between the patients with <1.0 and >1.0 gene amplification fold, the difference show a statistic significance(P<0.01). The DcR3 gene amplification fold of the patients with positive mRNA expressio...