APE1 Asp148Glu gene polymorphism and bladder cancer risk: a meta-analysis.

Published data regarding the association between the apurinic/apyrimidinic endonuclease 1 (APE1) Asp148Glu polymorphism and bladder cancer risk showed inconclusive results. This meta-analysis of literatures was performed to draw a more precise estimation of the relationship. We systematically searched PubMed, Embase, Elsevier and Springer for relevant articles with a time limit of Jan. 2012. The strength of association between APE1 Asp148Glu polymorphism and bladder cancer risk was assessed by odds ratio (OR) with the corresponding 95 % confidence interval (95 % CI) using the software STATA(version10.0).A total of 11 case-control studies including 4,292 cases and 4,761 controls based on the search criteria were included for analysis. Overall, for GG versus TT, the pooled OR was 0.952 (95 % CI = 0.778-1.166), for the the G allele carriers (TG + GG) versus homozygote TT, the pooled OR was 0.984 (95 % CI = 0.897-1.078). In the stratified analysis by ethnicity, significantly risks were not found among Asians for GG versus TT (OR = 0.469; 95 % CI = 0.162-1.357) nor (TG + GG) versus TT (OR = 0.921, 95 % CI = 0.742-1.143). Similarly, for non-Asians, significantly risks were also not found for GG versus TT (OR = 0.992; 95 % CI = 0.861-1.144) nor (TG + GG) versus TT (OR = 1.010, 95 % CI = 0.897-1.137). This meta-analysis suggested that the APE1 T1349G (Asp148Glu) polymorphism was not associated with bladder cancer risk among Asians nor non-Asians.

Investigation of transcriptional gene silencing and mechanism induced by shRNAs targeted to RUNX3 in vitro.

AIM: To investigate transcriptional gene silencing induced by short hairpin RNAs (shRNAs) that target gene prompter regions of RUNX3 gene, and whether shRNAs homologous to DNA sequences may serve as initiators for methylation. METHODS: According to the principle of RNAi design, pSilencer3.1-H1-shRNA/RUNX3 expression vector was constructed, The recombinant plasmid shRNA was transfected into human stomach carcinoma cell line SGC7901 with Lipofectamine 2000. Then, the positive cell clones were screened by G418. The mRNA and protein expression level of RUNX3 in the stable transfected cell line SGC7901 were determined by RT-PCR, Western blotting and immunocytochemistry. Characteristics of the cell lines including SGC7901, pSilencer3.1-H1/SGC7901 and pSilencer3.1-H1-shRNA/RUNX3/SGC7901 were analyzed with growth curves, clone formation rate and cell-cycle distribution. The activated level of RUNX3 was examined after treatment with the different density of 5'-aza-2'-deoxycytidine (5-Aza-CdR) by using semi-quantitative RT-PCR and Western blotting. RESULTS: In the cell line SGC7901 transfected with pSilencer3.1-H1-shRNA/RUNX3, mRNA and protein expression of the RUNX3 gene was lost identified by RT-PCR, Western blotting and immunocytochemistry assay. The growth of pSilencer3.1-H1-shRNA/ RUNX3/SGC7901 cells without expression of RUNX3 was the fastest (P < 0.05), its rate of clone formation was the highest (P < 0.01), and the cell distribution in G(0)/G(1) and S/M phases was lowest and highest, respectively (P < 0.05), compared with that of the transfected pSilencer3.1-H1 and non-transfected cells. Through RT-PCR and Western blot assay, inactivated RUNX3 could not be reactivated by 5-Aza-CdR. CONCLUSION: We found that, although shRNAs targeted to gene prompter regions of RUNX3 could effectively induce transcriptional repression with chromatic changes characteristic of inaction promoters, this was independent of DNA methylation, and the presence of RNA-dependent transcriptional silencing showed that RNA-directed DNA methylation might be an existing gene regulatory mechanism relative to the methylated in humans.

Anti-proliferative and pro-apoptotic effect of carvacrol on human hepatocellular carcinoma cell line HepG-2.

Carvacrol is one of the members of monoterpene phenol and is present in the volatile oils of Thymus vulgaris, Carum copticum, origanum and oregano. It is a safe food additive commonly used in our daily life, and few studies have indicated that carvacrol has anti-hepatocarcinogenic activities. The rationale of the study was to examine whether carvacrol affects apoptosis of human hepatoma HepG2 cells. In this study, we showed that carvacrol inhibited HepG2 cell growth by inducing apoptosis as evidenced by Hoechst 33258 stain and Flow cytometric (FCM) analysis. Incubation of HepG2 cells with carvacrol for 24 h induced apoptosis by the activation of caspase-3, cleavage of PARP and decreased Bcl-2 gene expression. These results demonstrated that a significant fraction of carvacrol treated cells died by an apoptotic pathway in HepG2 cells. Moreover, carvacrol selectively altered the phosphorylation state of members of the MAPK superfamily, decreasing phosphorylation of ERK1/2 significantly in a dose-dependent manner, and activated phosphorylation of p38 but not affecting JNK MAPK phosphorylation. These results suggest that carvacrol may induce apoptosis by direct activation of the mitochondrial pathway, and the mitogen-activated protein kinase pathway may play an important role in the antitumor effect of carvacrol. These results have identified, for the first time, the biological activity of carvacrol in HepG2 cells and should lead to further development of carvacrol for liver disease therapy.