OBJECTIVETo investigate the prognostic value of lymphatic vascular invasion (LVI) for stage I( gastric cancer patients after radical gastrectomy.

METHODSClinicopathological and intact follow-up data of 469 stage I( gastric cancer patients who underwent radical gastrectomy with R0 resection and were pathologically proven as gastric adenocarcinoma without other malignancy at the Department of Digestive Surgery, The First Affiliated Hospital, The Fourth Military Medical University between February 2009 and December 2012 were retrospectively collected. Chi square test was used to examine the relationship between LVI and clinicopathological data; Log-rank test was used for survival analysis; Cox proportional hazards model was used for univariate and multivariate analysis to explore the prognostic influence of LVI on stage I( gastric cancer patients.

RESULTSA total of 469 patients were enrolled, including 360 male (76.8%) and 109 female patients (23.2%). Median age was 58(25-82) years. There were 114 T1a cases (24.3%), 195 T1b cases (41.6%), and 160 T2 cases (34.1%). There were 439 (93.6%) cases without lymph node metastasis and 30 cases with lymph node metastasis. Presence of LVI was found in 52 patients (11.1%). LVI was closely associated with tumor grade, depth of invasion and status of lymph node metastasis (all P<0.05), rather than gender, age, tumor location and tumor diameter (all P>0.05). LVI detection rate was higher in poorly differentiated and undifferentiated group (14.3%, 32/223) than that in moderately and well differentiated group (8.1%, 20/246) (χ=4.590, P=0.032). LVI detection rate was higher in T2 (14.4%, 23/160) and T1b (13.3%, 26/195) group than that in T1a group (2.6%,3/114)(χ=11.020, P=0.004). LVI detection rate was higher in patients with lymph node metastasis (30.0%, 9/30) compared to those without lymph node metastasis (9.8%, 43/439) (χ=11.629, P=0.001). Median follow-up time was 63(3-74) months. There were totally 46 deaths (9.8%). The 5-year overall survival rate was 90.2%. The 5-year overall survival rate was 82.7% in patients with LVI and 91.1% without LVI, which was significantly different (P=0.039). Univariate analysis showed that age (P=0.012), AJCC T stage (8th edition) (P=0.011), and LVI (P=0.043) were closely associated with the prognosis of gastric cancer patients, while gender, tumor location, tumor diameter, tumor grade, lymph node metastasis or postoperative chemotherapy were not associated to the prognosis (all P>0.05). Multivariate analysis revealed that only age(HR=2.038, 95%CI:1.126 to 3.686, P=0.019) and advanced T stage (T1b: HR=1.427, 95%CI:0.554 to 3.678; T2: HR=2.926, 95%CI:1.199 to 7.140; P=0.017) were independent prognostic factors of stage I( gastric cancer patients (both P<0.05).

CONCLUSIONSLVI is not an independent prognostic factor of stage I( gastric cancer patients. In clinical practice, we should consider adjuvant chemotherapy prudently for stage I( gastric cancer patients with LVI.

Objective: To investigate the expression of Formin-2（FMN2）protein in gastric cancer tissues and its correlation to clinicopathological features of gastric cancer patients, as well to explore its effect on the proliferation of gastric adenocarcinoma AGS cells. Methods: 84 cases of gastric adenocarcinoma tissues and corresponding para-cancerous tissues were surgically collected from patients treated in the First Affiliated Hospital of Air Force Military Medical University from September 2015 to September 2017. The expression of FMN2 in gastric adenocarcinoma tissues was detected by immunohistochemical staining and analyzed with RNA-Seq data-sets GEPIA. The relationship between FMN2 protein expression in gastric adenocarcinoma tissues and its clinicopathological features was also explored. MTT assay was used to detect the effect of FMN2 onAGS cell proliferation activity, and Western blotting was used to detect the effect of FMN2 on the expression of apoptosis-related protein caspase-3 in AGS cells. Results: The expression level of FMN2 in gastric adenocarcinoma tissues was significantly lower than that in matched adjacent tissues and the expression level of FMN2 was closely related to the TNM stage and differentiation of gastric adenocarcinoma (all P<0.05). Compared toAGS control group, the proliferation activity of AGS/FMN2 was significantly decreased and the expression of apoptosis-related gene Caspase-3 was markedly increased (all P<0.05). Conclusion: The expression of FMN2 was significantly decreased in gastric adenocarcinoma tissues and its low expression is closely related to the degree of tumor differentiation and clinical TNM stage. Moreover, FMN2 over-expression significantly decreased the proliferation of AGS cells. FMN2 may function as independent risk factor for the prognosis of gastric adenocarcinoma, which may provide new ideas for the treatment of gastric adenocarcinoma.

Objective: To investigate the expression of histone methyltransferase G9a in gastric cancer tissues and its correlation to prognosis, and to observe the effect of G9a inhibitor on the proliferation and apoptosis of gastric cancer cells. Methods: The expression level of G9a in gastric cancer tissues and its correlation to prognosis were analyzed by using the Kaplan-Meier Plotter and Oncomine database. Human gastric cancer cell line SGC-7901 and MKN-45 were selected as study subject. The expression level of G9a protein was detected by Western blotting. The morphological change of gastric cancer cells after the treatment of G9a inhibitor BIX01294 was observed. CCK-8 proliferation experiment and plate colony formation assay were used to examine the proliferation ability and clone formation rate of gastric cancer cells. The changes of cell apoptosis were detected by Annexin-V staining. Results: G9a was highly expressed in gastric cancer tissues (P<0.01), and the high expression of G9a was positively correlated with poor prognosis of gastric cancer patients (P<0.01). After the treatment of BIX01294, the morphology of gastric cancer cells was changed, the volume of gastric cancer cells reduced, the intercellular connections disappeared, and even the apoptotic manifestations appeared, such as the shrinking,, becoming round and cast-off etc. BIX01294 could significantly inhibit the proliferation and colony formation but promote the apoptosis of gastric cancer cells (all P<0.05). Conclusion: Histone methyltransferase G9a was highly expressed in gastric cancer tissues, and its high expression level was positively correlated with poor prognosis. The proliferation of gastric cancer cells was obviously inhibited while the apoptosis was significantly promoted after inhibiting G9a expression.