BACKGROUND: The transcription factor POU2F1 regulates the expression levels of microRNAs in neoplasia. However, the miR-29b1/a cluster modulated by POU2F1 in gastric cancer (GC) remains unknown. METHODS: Gene expression in GC cells was evaluated using reverse-transcription polymerase chain reaction (PCR), western blotting, immunohistochemistry, and RNA in situ hybridization. Co-immunoprecipitation was performed to evaluate protein interactions. Transwell migration and invasion assays were performed to investigate the biological behavior of GC cells. MiR-29b1/a cluster promoter analysis and luciferase activity assay for the 3'-UTR study were performed in GC cells. In vivo tumor metastasis was evaluated in nude mice. RESULTS: POU2F1 is overexpressed in GC cell lines and binds to the miR-29b1/a cluster promoter. POU2F1 is upregulated, whereas mature miR-29b-3p and miR-29a-3p are downregulated in GC tissues. POU2F1 promotes GC metastasis by inhibiting miR-29b-3p or miR-29a-3p expression in vitro and in vivo . Furthermore, PIK3R1 and/or PIK3R3 are direct targets of miR-29b-3p and/or miR-29a-3p , and the ectopic expression of PIK3R1 or PIK3R3 reverses the suppressive effect of mature miR-29b-3p and/or miR-29a-3p on GC cell metastasis and invasion. Additionally, the interaction of PIK3R1 with PIK3R3 promotes migration and invasion, and miR-29b-3p , miR-29a-3p , PIK3R1 , and PIK3R3 regulate migration and invasion via the phosphatidylinositol 3-kinase/protein kinase B/mammalian target of rapamycin (PI3K/Akt/mTOR) pathway in GC cells. In addition, POU2F1 , PIK3R1 , and PIK3R3 expression levels negatively correlated with miR-29b-3p and miR-29a-3p expression levels in GC tissue samples. CONCLUSIONS The POU2F1 - miR-29b-3p / miR-29a-3p-PIK3R1 / PIK3R1 signaling axis regulates tumor progression and may be a promising therapeutic target for GC.
MicroRNAs/metabolism* ; Humans ; Stomach Neoplasms/pathology* ; Cell Line, Tumor ; Cell Movement/physiology* ; Phosphatidylinositol 3-Kinases/metabolism* ; Animals ; Mice ; Octamer Transcription Factor-1/metabolism* ; Mice, Nude ; Class Ia Phosphatidylinositol 3-Kinase/metabolism* ; Neoplasm Invasiveness ; Gene Expression Regulation, Neoplastic/genetics* ; Male ; Immunohistochemistry ; Female

Objective To evaluate the use of diffusion-weighted imaging(DWI)for early detection of tumor response to Angiostatin-Endostatin(Statin-AE)fusion gene therapy in a rat C6 glioma model.Methods Fifty male wistar rats with C6 tumor cells implanted into the striatum were examined by a 3.0T MR scanner,then the rats beating tmors were divided into two groups,treatment group and control group.Rats in the treatment group received 107 plaque forming unit(pfu)recombinant herps simplex viral (R-HSV)mediated Statin-AE fusion gene therapy on day 7,and then the tumors were conformed on MRI.Conventional MR and DWI examination were acquired on 1,2,3 weeks after implantation with a 5-inch surface coil.Two(1 w),eight(2 w)and all the residual rats(3 w)of each group were sacrificed to perform the histopathological examination after each MBI examination.Pretreatment and post treatment tumor volulnes and apparent diffusion coefficient(ADC)values were calculated.Rank sum test and t test were employed for statistical analysis.Results On MRI,43 rats demonstrated tumors on day 7 with a successful rate of 86%,On week 2,the tumor volumes of the controh and treatment group were 90.6 and 91.64 mm3,with no significant difference(Z=-0.14,P＞0.05).On week 3,the tumor volumes of the controls and treatment group were 156.64 and 29.64 mm3,and a significant difference was observed(Z=-3.45,P＜0.01).On week 2.the ADC values of the tumor centers of the treatment group and the control group were (1.20±0.25)×10-3 and(0.99±0.08)×10-3 mm2/s,and the values of the tumor peripheral parts of the two groups were(1.00±0.25)×10-3 and(0.83±0.12)×10-3mm2/s,the ADC values of both tumor centers and peripheral parts of the treatment group were significantly higher than those of the control group (t=-0.82 and-0.46,P＜0.05).On week 3,the ADC values of the tumor centers of the treatment group and the control group were(0.92±0.21)× 10-3 and(0.99±0.09)×10-3mm2/s,and the values of the tumor peripheral parts of the two groups were(0.81±0.19)×10-3 and(0.78±0.11)×10-3 mm2/a,there were no statisfical difference between the two groups(t=0.82,and-0.46,P＜0.05).HE stained slices showed more prominent tumor interstifial edenla.swelling and death of tumor cells in the treated rats than the controls.Conclusions Combination of conventional MRI and DWI can be powerful to monitor tumor progression and therapy effecL Conventional MRI showed that the therapy slow the tumor progression in size while DWI demonstrated the tumor response even earlier than size change.DWI has potential use forthe detection of early response to antiangiogenic gene therapy.