The Study Of Wnt4/JNK1 Expression In Esophageal Squamous Cell Carcinoma

Objective and background: Esophageal cancer is one of the most common type of malignant tumor of digestive tract, that happens at esophagus with high rate of fatality. About 90% of esophageal cancer in China belongs to esophageal squamous cell carcinoma(ESCC). Epidemiology shows associations between the occurrence of ESCC and poor nutritional condition, bad eating habits, family-genetic risk factors and various causes of chronic inflammation. Along with the development of molecular biology, there is the understanding that the development of esophageal cancer is a comprehensive process of multiple factors, phases, genes and regulations, involving physiological and pathological responses including cell proliferation, apoptosis, differentiation, adhesion, movement, angiogenesis etc. and at the molecular level, the changes of expression of proto-oncogenes and tumor suppressor genes and various proteins. Wnt signaling pathway consisting a series of complex signaling pathways, involves cell-secreted Wnt signaling molecules, downstream signaling molecules within cells, which plays an important role in the regulation of target gene expression and cell behavior, and past study found that abnormal Wnt pathways exist in the esophageal cancer and other tumors. Wnt4, one of the Wnt proteins that can elicit non-canonical pathways such as the JNK pathway, can regulate epithelial cell differentiation, and its down-regulation is associated with epithelial-mesenchymal transition of human squamous cell carcinoma. JNK1, a important messenger in non-canonical WNT signaling pathway, mediates the apoptosis of tumor cells. Ki67, a known nuclear antigen of cell proliferation, has been widely used to detect the proliferation activity of tumor tissue. This experiment was focused to study the expression of Wnt4 and JNK1 of the non-canonical Wnt/JNK pathway in ESCC, and their relationship with clinical factors, in search of their role in the development of ESCC.Method: Collecting and sorting clinical data and specimens of ESCC tissue and adjacent tissue to carcinoma; Applying semi-quantitative PCR method to detect Wnt4 and JNK1 m RNA expression in ESCC and adjacent tissues; The methods ofimmunohistochemical staining were used to detect Wnt4 and JNK1 protein expression in ESCC and adjacent tissues; Analyzing the correlation between clinical data and examining results, and discussing the relationship between Wnt4/JNK1 signaling pathway and pathological TNM stage, degree of differentiation, lymph node metastasis, the infiltration depth of ESCC.Result:(1) Both Wnt4, JNK1 m RNA expression level in ESCC tissues was lower than that in normal tissue adjacent to carcinoma with statistically significant difference(P < 0.05); Wnt4 m RNA expression level in high differentiation ESCC group was significantly higher than that in mid-low differentiation group statistically(P < 0.05), while there was no statistical difference between groups divided respectively according to gender, age, lymph node metastasis, pathological TNM stage and infiltration depth(P > 0.05); JNK1 m RNA expression was higher in group without lymph node metastasis than in group with lymph node metastasis, higher in I-II staging group than in III-IV staging group, both with significant difference statistically(P < 0.05), while no statistical correlation was found between JNK1 m RNA and gender, age or infiltration depth(P > 0.05).(2) Expression level of Wnt4, JNK1 and Ki67 protein in ESCC tissue was statistically different respectively compared with that in normal tissue adjacent to esophageal cancer(P < 0.05). Wnt4, JNK1 expression in ESCC significantly reduced, while Ki67 expressed in ESCC increased obviously. Wnt4 in high differentiation group was significantly higher than that in mid-low differentiation group statistically. Respectively, no statistical correlation was found between Wnt4 protein expression and gender, age, pathological TNM stage, lymph node metastases or infiltrating depth(P > 0.05); JNK1 protein expression in ESCC without lymph node metastasis was higher than that in ESCC with lymph node metastasis, higher in I-II stage group than in III-IV stage group, both with statistical significance(P < 0.05), while no statistical relationship was found respectively between JNK1 protein expression and gender, age, infiltration depth(P > 0.05). Positive rate of Ki67 in high differentiation ESCC group is lower than that in the poorly differentiated group, lower in I-II staging group than in III-IV staging group, both with statistical significance, Ki67 positive rate wasnot related to gender, age or infiltration depth statistically(P > 0.05).(3) At protein expression level, Wnt4 in ESCC was positively and negative correlated respectively with JNK1 and Ki67(P < 0.05), Pearson value being 0.394 and 0.307. No correlation was found between JNK1 and Ki67 protein expression(P > 0.05).Conclusion:(1) Down-regulation of Wnt4/JNK1 m RNA and protein level was found in ESCC compared to that in normal esophageal tissue, suggesting its anticancer role in the occurrence and development of ESCC;(2) A trend of decrease in Wnt4 expression level was showed with the increase of malignant degree of ESCC, suggesting that reduced Wnt4 expression may associate with poor differentiation in ESCC.(3) JNK1 expression level decreased significantly with the presence of lymphatic metastasis and increasing p TNM stage, suggesting that reduced JNK1 expression may correlate with lymph node metastasis and high p TNM stage respectively.(4) Ki67 expression was up-regulated in ESCC, especially higher in ESCC with poorer differentiation and higher pathological TNM stage, suggesting that high Ki67 expression maybe relative with malignant progression of ESCC.(5) Protein expression of Wnt4 in ESCC may be positively correlated with that of JNK1 and negatively with that of Ki67, while no relationship was detected between protein expression of JNK1 and Ki67.