Objective To compare the diagnostic value of 3.0T and 1.5T magnetic resonance diffusion weighted imaging (DWI) in lymph node metastasis of gastric cancer. Methods Preoperative magnetic resonance examination was performed on 50 patients with gastric cancer by using Siemens 1.5T and 3.0T superconducting magnetic resonance imaging system, and the outcomes were compared with postoperative pathological results. The sensitivity, specificity and accuracy of the diagnosis in lymph node metastasis of gastric cancer were analyzed statistically. The apparent diffusion coefficient (ADC) values of lymph nodes were also evaluated for 1.5T and 3.0T magnetic resonance DWI. Results The sensitivity, specificity and accuracy of the diagnosis on lymph node metastasis of gastric cancer by 1.5T magnetic resonance DWI were 79.4 %, 81.4%and 80.0%, respectively, and the corresponding percentages of 3.0T magnetic resonance DWI were 84.6%, 79.7%and 83.1%. The accuracy rate of 3.0T magnetic resonance DWI was slightly higher than that of 1.5T in the diagnosis of lymph node metastasis of gastric cancer (χ2=5.451, P=0.020), but there were no significant differences in the sensitivity and specificity between the two groups (both P> 0.05). The accuracy rate of 1.5T magnetic resonance DWI in the diagnosis of lymph node metastasis of gastric cancer was less effective than that of the pathological diagnosis (χ2=7.410, P=0.007), but there was no significant difference between 3.0T magnetic resonance DWI and pathological diagnosis (χ2=2.450, P=0.120). The mean ADC values of metastatic and non-metastatic lymph nodes detected by 1.5T magnetic resonance DWI were (1.036 ±0.203) × 10-3 mm2/s and (1.476 ± 0.215) × 10-3 mm2/s (t= 6.813, P< 0.001), meanwhile, the corresponding values detected by 3.0T magnetic resonance DWI were (1.154 ± 0.183) × 10-3 mm2/s and (1.502 ± 0.264) × 10-3 mm2/s (t= 5.991, P< 0.001). The coincidence of the two methods for ADC value was favorable. Conclusions The diagnostic effect of 3.0T magnetic resonance DWI on lymph node metastasis of gastric cancer is better than that of 1.5T. ADC value provides a reliable imaging quantitative indicator for the determination of metastatic lymph nodes in gastric cancer, which plays a significant role in the clinical treatment options and prognosis of patients.

Objective To evaluate the expression of metastasis-associated lung adenocarcinoma transcript 1 (MALAT-1) in ovarian cancer cell lines, and to investigate the biological effects of down-regulated MALAT-1 on OVCAR3 cells.Methods qRT-PCR analysis was used to examine the expression level of MALAT-1 gene in ovarian cancer cells, including ES-2, A2780, SKOV3 and OVCAR3 cell lines.For functional research, four shRNA oligos specially targeting MALAT-1 and a empty vector were designed and constructed into pGPU6/GFP/Neo, then transfected into OVCAR3 cells.qRT-PCR was used to confirm the effective suppression of MALAT-1.Changes of proliferation and adhesion of cells were analyzed by CCK-8 and adhesion assays.Wound-healing, transwell migration and invasion assays were used to examine migration and invasion of MALAT-l-silencing cells in vitro.Results The expression of MALAT-1 gene in OVCAR3 cells was high, and qRT-PCR results confirmed successfully the knockdown of MALAT-1 after transient transfection.After successful suppression of MALAT-1, the proliferation, wound-healing and adhesion ability in vitro were inhibited to some degree.In transwell migration assay, the number of migration cells in MALAT-1-silencing group was 52.17±4.48, which is much less than that in the negative and control groups (286.50± 12.23 and 295.67±6.96, respectively).In invasion assay, the number of invasion cells passing the transwell membrane in MALAT-1-silencing group (37.33±2.40) was also decreased significantly, compared to that in the negative and control groups (239.00±15.72 and 222.67±20.85, P ＜ 0.05).Conclusions shRNA-mediated silence of MALAT-1 can effectively inhibit the proliferation, adhesion, migration and invasion abilities of ovarian cancer cell line OVCAR3 in vitro, indicating MALAT-1 is expected to be a target gene for the treatment of ovarian cancer.