MicroRNA-107 promotes proliferation of gastric cancer cells by targeting cyclin dependent kinase 8.

BACKGROUND: The biological processes and molecular mechanisms underlying miR-107 remain unclear in gastric cancer(GC). In this study, we aimed to investigate the expression, biological functions and mechanisms of miR-107 in GC. METHODS: Quantitative real-time RT-PCR was used to test miR-107 expression. MTT and colony formation assays were conducted to explore the potential function of miR-107 in human GC cell line SGC7901. The target gene was determined by bioinformatic algorithms, dual luciferase reporter assay, RT-PCR and Western blot. RESULTS: Expression of miR-107 was significantly elevated in GC cell line than that in gastric epithelial cell line(p = 0.012). We found that miR-107 inhibitor transfection significantly decreased the proliferation of GC cell line, and clone formation rate of miR-107 inhibitor transfected group was significantly lower than that of control group. Luciferase assays using a reporter carrying a putative miR-107 target site in the 3'untranslated region (3'-UTR) of cyclin dependent kinase 8 (CDK8) revealed that miR-107 directly targets CDK8. The expression level of CDK8 mRNA and protein in miR-107 inhibitor transfected GC cell line was significantly decreased compared with control group. CONCLUSION: Our findings indicate that miR-107 is upregulated in GC and affects the proliferation of GC cells, partially through the regulation of CDK8. VIRTUAL SLIDES: The virtual slide(s) for this article can be found here: http://www.diagnosticpathology.diagnomx.eu/vs/13000_2014_164.

[NF-κb inhibitor PDTC enhances tumor necrosis factor α-induced apoptosis of gastric cancer cell SGC-7901].

OBJECTIVE: To investigate the effect of PDTC (inhibitor of NF-κb) on apoptosis of human gastric cancer cell line SGC-7901 induced by tumor necrosis factor α (TNF-α) and explore the related mechanisms. METHODS: After the treatment with different concentrations of PDTC, TNF-α or PDTC combined with TNF-α on gastric cancer cell line SGC-7901, the growth inhibition of SGC-7901 was measured by MTT assay. Hoechst was used to assess SGC-7901 cell apoptosis. The protein expressions of survivin and caspase-3 were detected by Western blot assay. RESULTS: The growth inhibition rate of SGC-7901 induced by PDTC (15, 30, 60, 100 µmol/L) was (12.14±0.91)%, (20.00±1.11)%, (37.63±1.01)% and (41.46±1.07)%. Different concentrations of PDTC all inhibited the growth of SGC-7901 significantly (all P<0.01), The growth inhibition rate of SGC-7901 induced by 25 mg/L TNF-α was (2.38±0.67)%, which could not significantly inhibit the growth of SGC-7901 [control (1.50±0.81)%], while TNF-α of 50, 100, 150 mg/L could inhibit the growth of SGC-7901 significantly [(4.53±0.85)%, (4.43±0.70)% and (4.74±1.07)%, all P<0.05]. PDTC (15 µmol/L) combined with TNF-α (25, 50, 100, 150 mg/L) significantly increased the cell growth inhibition rate compared with TNF-α alone or PDTC 15 µmol/L alone (all P<0.01). Hoechst assay showed that 100 mg/L TNF-α, 15 µmol/L PDTC and combination of above two all induced cell apoptosis (P<0.01), and the combination group had significantly higher percentage of cell apoptosis (P<0.01). Survivin protein was significantly down-regulated in combination group as compared with single TNF-α (100 mg/L) group, but was not significant down-regulated as compared with single PDTC (15 µmol/L) group. Caspase-3 protein expression was significantly increased in combination group as compared with other two groups. CONCLUSION: PDTC can enhance the cell apoptosis induced by TNF-α, which may be associated with the blocking of TNF-α-activated NF-κB signaling pathway by PDTC, the down-regulation of survivin expression, and up-regulation of caspase-3 expression.

[Study of inhibiting and killing effects of transgenic LIGHT human umbilical cord blood mesenchymal stem cells on stomach cancer].

OBJECTIVE: To study the inhibition and killing effect of transgenic LIGHT umbilical cord blood mesenchymal stem cells (UCBMSCs) on stomach carcinoma. METHODS: The LIGHT gene was recombined to construct the transfer plasmid pGC-FU-LIGHT by infusion technique. The 293T cells were co-transfected with the transfer plasmid pGC-FU-LIGHT, the construction plasmid Helper 1.0 and the envelope plasmid Helper 2.0 with the help of lipofectamine 2000 to produce lentiviral particles. Transgenic UCBMSCs(MSC-LIGHT) and empty carrier UCBMSCs (MSC) were obtained. Human gastric cancer cell SGC-7901 was injected into nude mice subcutaneously groin. The model of transplanted human gastric cancer cell SGC-7901 in nude mice was established. Tumorigenesis nude mice were separated into three groups randomly with 5 in each group: MSC-LIGHT group, MSC group, and NS group. Three groups of nude mice were injected around the tumor with MSC-LIGHT, MSC and NS every other day for 3 times. Four weeks later, the transplanted gastric cancer volume was measured. The expressions of LIGHT in the three groups were determined by RT-PCR and ELISA method. The necrosis area in the tumors was calculated under pathological examination. RESULTS: The average volume of transplanted tumor was(0.45±0.25) cm(3) in MSG-LIGHT group, (0.64±0.36) cm(3) in MSG group, and(1.21±0.79) cm(3) in NS group, and the difference was statistically significant(P<0.05). The LIGHT mRNA was 2.96±0.27, 1.23±0.47, and 0.73±0.10 respectively. The LIGHT protein was(167.89±2.31), (73.22±5.74), and (49.66±5.25) ng/L. The differences were all statistically significant among the three groups(both P<0.01). Pathological examination showed that the necrosis area was largest in MSC-LIGHT group. CONCLUSION: Transgenic UCBMSCs secret LIGHT in a paracrine manner, which has inhibition and killing effects on stomach carcinoma.