| Gastric cancer is one of the most common malignancies in the world.East Asia,where China is located,has a particularly high incidence.The latest cancer data in China show that gastric cancer morbidity and mortality have both risen to the second place.The clinical symptoms and signs of early gastric cancer patients are not obvious,while the lack of specific sensitivity of the screening index,the majority of patients with initial diagnosis have been in the advanced phase and the cancer can not be resected.Relative to breast cancer,non-small cell lung cancer,and colorectal cancer,which have made great progress of treatment in recent years,chemotherapy and targeted treatment of advanced gastric cancer has little progress and the median overall survival is still maintained at 1 year or so.Therefore,the molecular mechanisms and clinical application of regulation of cell growth,differentiation,apoptosis,metastasis have been the current research hot spots in gastric cancer.Human epidermal growth factor receptor-2(HER2)is one of the members of the ErbB receptor tyrosine kinase family.At present,the cell surface HER2 protein overexpression,suggesting a high degree of malignancy,rapid progress,chemotherapy remission,radiotherapy and chemotherapy and endocrine therapy easy to produce resistance,so that the patients have shortened disease-free survival and overall survival.Because HER2 is located on the cell surface,it is an ideal target for anti-tumor therapy.Anti-HER2 targeted therapy has been encouraging in breast cancer research.In gastric cancer,HER2 overexpression accounts for about 3.7%to 20.2%of all patients with gastric cancer.In recent years,researching the role of HER2 in the development of gastric cancer,will help the development of new anti-tumor drugs.Malignant tumor cells can still increase glycolysis under aerobic conditions,and this metabolic change is called the Warburg effect.Lactate dehydrogenase A(LDHA)catalyzes the conversion of pyruvate to lactic acid as a key step in glycolysis.LDHA has been elevated in many types of cancer and is thought to be associated with tumor proliferation,growth,invasion and metastasis.Inhibition of LDHA can limit the energy supply in cancer cells,thereby reducing the potential for cancer cell metastasis and invasion.LDHA can be overexpressed in most gastric cancer,and many studies have suggested that LDHA is also a potential target for treatment in gastric cancer.Objectives:The aim of this study is to investigate the regulatory relationship between HER2 and LDHA,and to clarify the molecular mechanism and clinical significance of HER2 in regulating the progression of gastric cancer via LDHA.Methods:1.The clinical data of 179 cases of gastric cancer were analyzed statistically the correlation between HER2 and serum LDH,and the relationship with clinicopathological features.2.The correlation between HER2 and LDHA expression was analyzed by using 12 pairs of immunohistochemical specimens of gastric cancer with HER2 positive and negative expression.3.Three cell lines,HGC-27,SGC-7901 and NCI-N87,which were expressed by HER2,were used as the cell models of this study,and the correlation between HER2 and LDHA expression at cell level was analyzed by immunofluorescence imaging.4.The LDHA expression in HGC-27,SGC-7901 and NCI-N87 cells was interfered by siRNA,and the effects on the proliferation,invasion and migration of gastric cancer cells were detected.Western blotting,CCK8,scratch test,and Transwell were used.5.The activity of lactate dehydrogenase were detected by regulating the expression of HER2 and LDHA in cell models.6.Overexpression and interference of HER2 were performed to detect the expression of HIF-1 a and LDHA with Western blotting.Moreover,the expression of HER2,HIF-1 a and LDHA with Western blotting was detected in 7 pairs of fresh gastric cancer tissues and corresponding adjacent tissues.Results:1.The clinical data of 179 cases of gastric cancer were statistically analyzed.The positive rate of HER2 was 16.2%,the positive rate of HER2 in gastroesophageal junction was higher than that in gastric antrum but not statistically significant,which may be related to the sample size.The positive expression of HER2 was correlated with the degree of histological differentiation of gastric cancer(P=0.007).The positive expression of HER2 in gastric cancer was associated with elevated serum LDH(P=0.027).Elevated serum LDH was positively correlated with maximal diameter(P=0.035)and distant metastasis(P<0.001)of gastric cancer.2.The expression of LDHA was significantly correlated with HER2 in paraffinembedded histopathological gastric cancer specimens(P=0.0308).3.In HGC-27 SGC-7901 and NCI-N87 cell lines,the results of double immunofluorescence imaging showed that HER2 and LDHA were positively correlated at cell level.4.The migration of HGC-27 and SGC-7901 cells was observed by interfering with the expression of LDHA protein via siRNA.By using wound healing assay and transwell assay,it was confirmed that these two kinds of cell invasion,migration was significantly reduced(P<0.001).In the NCI-N87 cell strain,Transwell assay also confirmed that cell migration was also significantly reduced by silencing LDHA(P<0.001).5.Lactate dehydrogenase activity was increased after HER2 WT plasmid was transfected into HGC-27 and SGC-7901 cells(P<0.05),while it was decreased after transfection of LDHA-siRNA(P<0.05).The expression of LDHA in NCIN87 cells was inhibited by LDHA-siRNA,and the lactate dehydrogenase activity was also decreased(P<0.05).Moreover,the lactate dehydrogenase activity was significantly decreased by inhibition of HER2 expression via CP724714(P<0.001).6.HER2 WT and HER2-shRNA were used to regulat the expression of HER2 in HGC-27 and SGC-7901.The up or down regulated expression of HER2 could induce the similar up or down expression of HIF-1? and LDHA.The expression of HER2 protein in NCI-N87 cell line was observed by HER2-shRNA interference.It was found that low expression of HER2 could down-regulate HIF-1? and LDHA.The expression of HER2,HIF-la and LDHA in gastric cancer tissues was significantly higher than that in adjacent tissues,and they were similar overexpression in 5/7(71.4%)pairs of fresh gastric cancer tissues and corresponding adjacent normal tissues.We hypothesized that HER2 could play a certain role in gastric cancer through HIF-1?-LDHA signaling pathway and ultimately affect LDHA protein expression.Conclusions:In summary,in this study,we found that HER2 expression and serum LDH was closely related.There was high expression of LDHA in HER2 positive gastric cancer tissues and HER2-overexpressing gastric cancer cell lines.LDHA played an important role in the invasion and migration of gastric cancer cells.HER2 and LDHA could regulate lactate dehydrogenase activity.Regulating HER2 could cause more consistent expression of HIF-1? and LDHA.The results of this study provide new and important scientific evidence for elucidating the role of HER2-HIF-1?-LDHA signaling pathway in invasion and migration of gastric cancer.As key molecules in the regulation of gastric cancer by invasion and metastasis,they are possible to become potential targets for the treatment of gastric cancer or the prognostication biomarkers. |
PDF Full Text Request