Interaction of SerpinB5 and MAFbx in gastric cancer cell and its action site / 中华胃肠外科杂志

<p><b>OBJECTIVE</b>To explore the interaction between SerpinB5 and MAFbx in gastric cancer cell and to identify the interaction sites.</p><p><b>METHODS</b>The interaction between SerpinB5 and MAFbx was screened and validated by yeast two-hybrid screening and co-immunoprecipitation. The expression of MAFbx was analyzed after SerpinB5 expression being modified by RNA interference and pGBKT7-SerpinB5 transfection. The impact of SerpinB5 on the expression of MAFbx was studied in gastric cancer cell line SUN-16. A model of MAFbx was constructed by homology modeling. The related residues for interaction were analyzed by Autodock4.0.</p><p><b>RESULTS</b>The interaction between SerpinB5 and MAFbx was validated. The expression of MAFbx changed along with SerpinB5 expression. Amino acids including PRO261, ASN361, and LYS362 were key residue in the interaction of SerpinB5 and MAFbx.</p><p><b>CONCLUSION</b>SerpinB5 interacts with MAFbx in gastric cancer cell. Amino acids including PRO261, ASN361, and LYS362 are potential binding sites.</p>

Screening and identification of genes associated with multi-drug resistance in colonic cancer / 中华胃肠外科杂志

<p><b>OBJECTIVE</b>To identify novel multi-drug resistance-related genes, and to explore the mechanisms of multi-drug resistance.</p><p><b>METHODS</b>Multi-drug resistant cell line Lovo/5-FU was established by incubation with increasing dose of 5-FU. The sensitivity to 5-FU and cis-diaminodichloroplatinum (CDDP) was measured by MTT assay. Two dimensional electrophoresis plus mass spectrum(2-DE/MS) was used to identify the differentially expressed protein between Lovo and Lovo/5-FU. The identified protein was then verified by Western blot analysis.</p><p><b>RESULTS</b>The IC50 concentrations of Lovo/5-FU to 5-FU and CDDP were increased by 31 and 3 times, compared with Lovo (both P<0.01). 2DE-MS showed that CAP-G and RhoGDI2 were up-regulated, whereas 6-PGL, DCI, Prdx-6 and Maspin were down-regulated in Lovo/5-FU. Western blot analysis confirmed that the expression levels of RhoGDI2 and CAP-G in Lovo/5-FU were increased by 6.14 and 2.98 fold respectively (both P<0.01), whereas Maspin was decreased to 5.2% of Lovo(P<0.01).</p><p><b>CONCLUSIONS</b>Multi-gene and multi-pathway are involved in the development of multi-drug resistance of colorectal cancer cells. CAP-G, RhoGDI2 and Maspin are potential multi-drug resistant genes.</p>

Demethylation of the gamma-synuclein gene CpG island in colorectal cancer and its clinical significance / 中华胃肠外科杂志

<p><b>OBJECTIVE</b>To explore the relationship between gamma-synuclein gene expression and CpG island demethylation in colorectal cancer(CRC), and the relationship between the demethylation and clinicopathological factors of CRC.</p><p><b>METHODS</b>The expression of gamma-synuclein mRNA was examined in 30 pairs of tumor tissues and tumor-matched non-neoplastic adjacent tissues(NNAT) by RT-PCR. CRC cell lines including COLO205, LoVo, and SW480 were used and treated with a demethylating agent, 5-aza-2'-deoxycytidine(5-aza-C). Before and after the treatment, the expression of gamma-synuclein mRNA in the cells was determined by RT-PCR, and bisulfite sequencing PCR was also used to analyze methylation status of CpG island. The methylation status of gamma-synuclein was then examined in 67 CRC samples and 30 NNAT samples by nested methylation-specific PCR (NMSP) and real time methylation-specific PCR(real-time MSP). The relationship between the demethylation of gamma-synuclein in CRC and clinicopathological factors was analyzed.</p><p><b>RESULTS</b>The mean gamma-synuclein mRNA expression was 0.66+/-0.34 in CRC samples, which was much higher than 0.45+/-0.26 in NNAT samples(P=0.011). 5-aza-C could induce expression and demethylation of gamma-synuclein in COLO205, LoVo and SW480 cells. gamma-Synuclein gene was demethylated in 80.0%(24/30) of the CRC samples and 50.0%(15/30) of the NNAT samples. The demethylated status of gamma-synuclein was much higher in CRC samples than that in NNAT samples(P=0.030), and was significantly correlated with clinical stage, lymph node involvement, and distant metastasis of CRC(P<0.05).</p><p><b>CONCLUSION</b>The upregulation of gamma-synuclein expression in CRC is primarily attributed to the demethylation of CpG island, which may be used as a marker for prognosis.</p>

Silencing invariant chains of dendritic cells enhances anti-tumor immunity using small-interfering RNA / 中华医学杂志(英文版)

<p><b>BACKGROUND</b>Genetic modification of dendritic cells (DCs) has been used as an effective approach to enhance anti-tumor immunity. RNA interference (RNAi), which can cause the degradation of any RNA in a sequence-specific manner, is a post-transcriptional gene silencing mechanism. In this study, small-interfering RNA (siRNA) specific for the Ii gene was transfected into DCs, and the anti-tumor immunity of Ii-silenced DCs was assessed.</p><p><b>METHODS</b>The silencing effect of siRNA was evaluated by Western blotting and real-time PCR analyses. In vitro cytotoxic activity of T cells was evaluated using a Cytotox 96(®) non-radioactive cytotoxicity assay kit. The time to tumor onset and the tumor volumes were used as reliable indices to assess the anti-tumor immunity in vivo. To further examine the mechanisms underlying the anti-tumor immunity, flow cytometry analysis was used.</p><p><b>RESULTS</b>The Ii expression of DCs was significantly reduced after Ii siRNA transfection. Significant in vitro anti-tumor ability was exhibited when DCs were co-transfected with Ii siRNA plus endogenous tumor antigen (P < 0.05). Furthermore, tumor growth was greatly inhibited when mice were immunized with DCs transfected with Ii siRNA plus tumor antigen prior to or subsequent to tumor implantation. Flow cytometry analysis in vitro and in vivo indicated that both CD4(+) and CD8(+) T cells were significantly activated in the Ii siRNA group (P < 0.05).</p><p><b>CONCLUSION</b>Silencing of the Ii gene of DCs may offer a potential approach to enhance DC-based anti-tumor immunity.</p>