| Objective Intestinal type gastric cancer is the most common type of gastric cancer.Relevant data show that compared with other types of gastric cancer,the prognosis of intestinal type gastric cancer is better than other types of gastric cancer.Although the clinical research on intestinal gastric cancer has made some progress,the mechanism of the occurrence and development of intestinal type gastric cancer is still unclear.In this study,we detected the expression of lactate dehydrogenase A(LDH-A)in intestinal type gastric cancer tissues,and analyzed the relationship between LDH-A expression and clinicopathological characteristics of intestinal type gastric cancer,and explored the effect of knockdown of LDH-A on invasion and metastasis of intestinal type gastric cancer cells in vitro,and initially revealed the function and mechanism of LDH-A in epithelial mesenchymal transition(EMT)of intestinal type gastric cancer Early diagnosis and follow-up treatment of cancer provide theoretical basis and reference.Methods A total of 371 cases of primary intestinal type gastric cancer were collected from2011 to 2015.Cell lines included Human intestinal type gastric cancer cell line SGC7901 and Human immortalized gastric epithelial cell line GES.After the materials were collected,tissue samples and experimental cell lines were detected and analyzed by the following methods:1.Immunohistochemistry(IHC)and Western blot were used to detect the expression of LDH-A in intestinal type gastric cancer tissues and SGC7901 cells.2.The relationship between the expression of LDH-A and clinical features of gastric cancer was analyzed.3.The expression of LDH-A was knocked down in SGC7901 cell line in vitro,and the invasion and migration of intestinal type gastric cancer cell line were observed by Transwell cell invasion test.4.RT-PCR was used to detect the expression of E-cadherin,vimentin,fibronectin and Ncadherin in EMT,and to explore the effect of LDH-A knockdown on EMT.5.The expression of ZEB2 in SGC7901 cells with low LDH-A expression was detected by RT-PCR and Western blot.6.IHC staining was used to detect the expression of ZEB2 in intestinal type gastric cancer,and the correlation between the expression of LDH-A and ZEB2 was analyzed.7.To analyze the effect of ZEB2 expression on the prognosis of intestinal type gastric cancer,and to verify the effect of LDH-A / ZEB2 co expression on the clinical prognosis of intestinal type gastric cancer.Results 1.Compared with adjacent noncancerous tissues(paracancerous tissues),the positive rate of LDH-A protein expression in intestinal type gastric cancer was up-regulated(330.5 ± 40.2)%(P < 0.001).High expression of LDH-A was detected in 193 of 371 cases of intestinal type gastric cancer(52.0%),48 cases of 371 cases of adjacent tissues(12.9%),the difference was statistically significant(P < 0.001).Meanwhile,the expression of LDH-A in SGC7901 cell line and ges cell line showed that the expression level of LDH-A in SGC7901 cell line was significantly higher than that in ges cell line(81.7 ± 30.0)%(P < 0.001).2.The expression of LDH-A was positively correlated with tumor size(P = 0.033),depth of invasion(P < 0.001)and lymph node metastasis(P < 0.001),but not with age,gender,primary lesion location,distant metastasis and differentiation degree(P > 0.05).3.The invasion and migration ability of SGC7901 cells decreased by(46.63 ± 10.21)%and(52.48 ± 5.14)%,respectively,compared with those of SGC7901 cells without LDH-A knockdown(P < 0.001).4.In LDH-A knockdown SGC7901 cells,the expression of E-cadherin gene was upregulated(145.1 ± 6.7)%,the difference was statistically significant(P < 0.001);the expression of vimentin was down-regulated(52.3 ± 4.4)%(P < 0.001),but N-cadherin and fibronectin were not significantly changed(P > 0.05).It is suggested that LDH-A can affect cell invasion and migration by regulating EMT in vitro.5.In the LDH-A knockdown SGC7901 cells,the m RNA expression of ZEB2 was down regulated(58.1 ± 6.2)%,which was significantly different from that in the non knockdown group(P < 0.001),but the expression levels of snail and ZEB1 did not change significantly.Western blot also confirmed that in the LDH-A knockdown SGC7901 cell line,in addition to EMT related markers E-cadherin and vimentin,the expression level of ZEB2 protein was down regulated(68.5 ± 7.1)%,the difference was statistically significant(P < 0.05).It is suggested that LDH-A may promote EMT process by up regulating ZEB2 expression,thus affecting cell invasion and migration.6.Compared with the adjacent tissues,the expression of ZEB2 protein in intestinal type gastric cancer was significantly up-regulated(240.3 ± 30.4)%(P < 0.001).In 371 cases of intestinal type gastric cancer,207 cases(55.8%)were detected high expression of ZEB2,and only 45 cases(12.1%)were detected in adjacent tissue samples;the difference was statistically significant(P < 0.001).Correlation analysis showed that high expression of LDH-A accounted for 43.3% of ZEB2 negative tumors and 58.9% of ZEB2 positive tumors.There was a significant positive correlation between LDH-A and ZEB2 expression(P = 0.003).7.Univariate survival analysis showed that the survival rate of patients with high expression of ZEB2 was significantly lower than that of patients with low expression of ZEB2;similarly,the survival rate of patients with high expression of LDH-A was significantly lower than that of patients with low expression of LDH-A;the 5-year survival rate of LDH-A(+)/ZEB2(+)group was only 16.1%,significantly lower than that of other groups(68%;66%;55%),the difference was statistically significant(P < 0.05).In addition,according to multivariate survival analysis,ZEB2 expression was an independent prognostic factor for intestinal gastric cancer(P < 0.001).Tumor size(P = 0.001),depth of invasion(P = 0.017),regional lymph node involvement(P = 0.015)and distant metastasis(P = 0.002)were also independent prognostic factors.Conclusion 1.The expression of LDH-A was up-regulated in intestinal type gastric cancer tissues and cells,and its high expression was closely related to tumor size,invasion depth and lymph node metastasis.2.LDH-A promotes the invasion and migration of intestinal type gastric cancer cells by up regulating ZEB2 expression and thus promoting EMT. |
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