Role of activation-induced cell death in pathogenesis of patients with chronic hepatitis B

AIM: To study and compare the difference of activationinduced cell death (AICD) in peripheral blood T-lymphocytes (PBL-Ts) from patients with chronic hepatitis B (CHB) and the normal people in vitro, and to explore the role of AICD in chronic hepatitis B virus (HBV) infection and the pathogenesis of CHB.METHODS: Twenty-five patients and fourteen healthy people were selected for isolation of PBL-Ts. During cultivation, antiCD3 mAb, PMA and ionomycin were used for AICD of PBL-Ts.AICD ratio of PBL-Ts was detected with TdT-mediated dUTP nick end labeling and assessed by flow cytometry.RESULTS: When induced with anti-CD3, PMA and ionomycin in vitro, AICD ratio of PBL-Ts from CHB patients was significantly higher than that from healthy control (17.24±1.21VS. 6.63±1.00, P＜0.01) and that from CHB patients without induction (17.24±1.21 VS. 9.88±1.36, P＜0.0L). There was a similar AICD ratio of PBL-Ts between induction group and without induction group, but no difference was found before and after induction in healthy control. The density of INF-γ in culture media of induction groups of CHB was lower than that of other groups (P＜0.01). There was no difference between these groups in density of IL-10 (P＞0.05).CONCLUSION: When induced during cultivation in vitro,PBL-Ts from CHB have AICD very commonly. This phenomenon has a potentially important relation with pathogenesis of CHB and chronicity of HBV infection.

Expression of tumor related genes NGX6,NAG-7,BRD7 in gastric and colorectal cancer

AIM: NGX6, NAG-7 and BRD7 genes are tumor related genes, which have been newly cloned by positional candidate cloning strategy. This study was designed to investigate the expression levels of NGX6, NAG-7 and BRD7 genes in human gastric and colorectal cancer tissues, and their corresponding normal tissues, and to investigate whether these genes play a role in the pathogenesis of gastric and colorectal cancers.METHODS: Reverse transcription-polymerase chain reaction (RT-PCR), dot hybridization and Northern blot analysis were used to compare the expression levels of NGX6, NAG-7 and BRD7 genes in 34 gastric cancer tissues and 34 colorectal cancer tissues with their corresponding normal tissues of the same patients, respectively.RESULTS: Among the 34 colorectal cancer specimens and the 34 gastric cancer specimens, the expression of NGX6 in 25 colorectal cancer tissues was absent or very weak (73.5 %) by RT-PCR analysis. The down-regulation rate of NGX6 in colorectal cancer tissues was significantly higher than that in corresponding normal tissues (26.5 %,9/34)(P＜0.005). Moreover, the down-regulation of NGX6 was significantly correlated with lymph node and/or distance metastases. Patients with lymph node and/or distance metastasis had much higher down-regulation rate of NGX6 than patients without metastases (93.8 % vs 55.6 %, P＜0.05).However no correlation was found between the expression of NGX6 and pathologic type of colorectal cancer in this study, and also the expression of NGX6 did not display any difference between gastric cancer and corresponding normal tissues (58.8 % vs 70.6 %, P＞0.25). Dot hybridization and Northern blot analysis confirmed the results of RT-PCR.Furthermore, NAG-7 and BRD7 mRNA was not up- or downregulated in gastric and colorectal cancers compared with their corresponding normal tissues in our study.CONCLUSION: The down-regulation of NGX6 may be closely associated with tumorigenesis and metastasis of colorectal carcinoma. However, it may not contribute to the development and progression of gastric carcinoma. In addition, the expression levels of NAG-7, and BRD7 did not alter in gastric and colorectal cancers. This seems to suggest that NAG-7and BRD7 genes may not play a role in gastric and colorectal carcinogenesis.

A novel HBV antisense RNA gene delivery system targeting hepatocellular carcinoma

AIM: To construct a novel HBV antisense RNA delivery system targeting hapatocellular carcinoma and study its inhibitory effect in vitro and in vivo.METHODS: GE7,a 16-peptide specific to EGFR, and HA20,a homologue of N-terminus of haemagglutinin of influenza viral envelope protein, were synthesized and conjugated with polylysin. The above conjugates were organized into the pEBAF-as-preS2, a hepatocarcinoma specific HBV antisense expression vector, to construct a novel HBV antisense RNA delivery system, named AFP-enhancing 4-element complex. Hepatocelluar carcinoma HepG2.2.15 cells was used to assay the in vitro inhibition of the complex on HBV. Expression of HBV antigen was assayed by ELISA. BALB/c nude mice bearing HepG2.2.15 cells were injected with AFP-enhancing 4-element complex. The expression of HBV antisense RNA was examined by RT-PCR and the size of tumor in nude mice were measured.RESULTS: The AFP-enhancing 4-element complex was constructed and DNA was completely trapped at the slot with no DNA migration when the ratio of polypeptide to plasmid was 1:1.The expression of HBsAg and HBeAg of HepG2.2.15 cells was greatly decreased after being transfected by AFP-enhancing 4-element complex. The inhibitory rates were 33.4 % and 58.5 % respectively. RTPCR showed HBV antisense RNA expressed specifically in liver tumor cells of tumor-bearing nude mice. After 4injections of AFP-enhancing 4-element complex containing 0.2 μg DNA, the diameter of the tumor was 0.995 cm±0.35,which was significantly smaller than that of the control groups (2.215 cm±0.25, P＜0.05).CONCLUSION: AFP-enhancing 4-element complex could deliver HBV antisense RNA targeting on hepatocarcinoma and inhibit both HBV and liver tumor cells in vitro and in vivo.

Expression of tumor related gene NAG6 in gastric cancer and restriction fragment length polymorphism analysis

AIM: NAG6 gene is a novel tumor related gene identified recently. This study was designed to examine the expression of this gene in gastric cancer and corresponding normal tissues, and to investigate its role in the occurrence and development of gastric cancer, also to study if the genetic structure of NAG6 was altered in gastric cancer.METHODS: Reverse transcription-polymerase chain reaction (RT-PCR), Northern blot analysis and dot hybridization were used to compare the expression level of NAG6 gene in 42 cases of gastric cancer tissues with their corresponding normal tissues of the same patients respectively. In addition,restriction fragment length polymorphism (RFLP) analysis was adopted to study if the genetic structure of NAG6 was altered in gastric carcinomas.RESULTS: The expression of NAG6 in 57.1% gastric cancer tissues (25/42) was absent by RT-PCR analysis. The down-regulation rate of NAG6 in gastric cancer tissues was significantly higher than that in corresponding normal tissues(P<0.01). However no correlation between the down-regulation of NAG6 and lymph-node and/or distance metastasis was found in this study (P>0.05). Dot hybridization confirmed the results of RT-PCR. Furthermore,the results of EcoRI RFLP analysis of NAG6 gene demonstrated that 3 of 7 cases of gastric cancer showed loss of 5 kb fragment in comparison with their corresponding normal tissues.CONCLUSION: NAG6 gene is significantly down regulated in gastric cancer. The loss of genetic materials may be the cause of down-regulation of NAG6 expression. This seems to suggest that NAG6 may represent a candidate of putative tumor suppressor gene at 7q31-32 loci associated with gastric carcinoma. The down-regulation of this gene may play a role in occurrence and development of this disease, however it may not be associated with lymph node and/or distance metastasis.