The Expression And Significance Of E2F-1, PCNA, MDM2 And P53 In Esophageal Squamous Cell Carcinoma In Henan Linzhou City

Background and ObjectivesEsophageal carcinoma is a common malignant tumor of digestive system. It seriously endangers people's health. To study the pathogenesis of esophageal carcinoma will be of great help for clinical diagnosis and therapy.The study of epidemiology and etiology confirmed that the environment, age, gender, occupation, race, genetic factors and dietary habits had close relation with the incidence of esophageal carcinoma. In most cases, esophageal carcinoma has the invasion and metastasis before to be diagnosed. The incidence and development of tumors are a process involving multi-factors and multi-steps, which are associated with expression of oncogenes and tumor suppressor genes, abnormality of cell cycle regulation. E2F-1 is an important member of the transcription factors (E2Fs) family. Through regulations of cell proliferation, transcription and apoptosis, it can make the cell from G1 phase to S phase. It is closely related to apoptosis, proliferation and growth of tumor cells. Proliferating cell nuclear antigen (PCNA) plays an important role in cell cycle. The DNA synthesis and expression of PCNA represents cell proliferation. PCNA is a good index to reflect the proliferation of tumor cells. MDM2 gene is an oncogene. P53 gene is an important tumor suppressor gene. MDM2 and p53 regulates the cell cycle and participates in the incidence and development of most tumors.In this study, immunohistochemical assay was used to detect the expression of E2F-1, PCNA, MDM2 and p53 in esophageal squamous cell carcinoma in Henan Linzhou City, which is the highest incidence area in China. We investigate the correlation of the expressions with the clinical significance, which will provide basis theory for the clinical diagnosis and therapy.Materials and methods1 Specimen:Forty-nine cases of esophageal squamous cell carcinoma specimens were collected from August 2008 to March 2009. The normal esophageal tissue was chosed as control group, which was far away from the tumor more than 5cm. All the specimens were fixed by 10% formalin and paraffin-embedded. In 49 cases of esophageal squamous cell carcinoma,27 were male and 22 were female, aged between 46 to 87 years. The average age was 60.40±8.60. According to the International Union Against Cancer pathological standards, stageⅠwere 5 cases, stageⅡwere 31 cases and stageⅢwere 13 cases. High degree of differentiation was found in 10 cases, middle degree of differentiation 26 cases and low degree of differentiation 13 cases. Lymph node metastasis was found in 19 cases, no lymph node metastasis 30 cases. All patients had no pre-operation radiotherapy and chemotherapy.2 Research methods:In each specimen, six 4μm thick serial sections were made. Four were prepared for immunohistochemical assay (SP), one for HE staining and one for backup. The immunohistochemistry procedures were carried out according to kit instructions.3 The results of immunohistochemistry:The positive signal is claybank or sepia particles. The immuohistochemistry signals of E2F1, PCNA, MDM2 and p53 were located in the cell nucleus. In each slide,10 fields of high power resolution were randomly selected and in each field, we counted 100 cells. In these cells, the positive percentage was calculated.It is regarded as positive expression if the percentage of positive cells is more than 15% and regarded as negative expression if the percentage of positive cells is less than 15%. 4 Statistic analysis:All of the data were analyzed by SPSS13.0 statistical software. We compared the positive rate between two groups byχ2 test. The correlations between groups were analyzed by Pearson correlation analysis. The significance level was defined as a=0.05.Results1 The expression of E2F-1:The positive rate of E2F-1 in normal esophageal tissue was 8.16%, and in esophageal squamous cell carcinoma tissue was 51.02%. There was a statistical difference. The positive rates of E2F1 in esophageal squamous cell carcinoma tissue with lymph node metastasis or not were 78.95% and 33.33%. The positive rates of E2F-1 in high-middle and low differentiated carcinoma tissue were 38.89% and 84.62%. The positive rates of E2F1 in esophageal squamous cell carcinoma tissue accompanied by fibrous membrane invasion and non fibrous membrane invasion were 70.00% and 37.93%. The positive rates of E2F-1 on different TNM stage (Ⅰ,ⅡandⅢ) of esophageal carcinoma was 20.00%,35.48% and 84.62% respectively. The positive rate of E2F-1 was uncorrelated with gender and age. The positive rate of E2F-1 was correlated with degree of differentiation, TNM stage, lymph node metastasis and depth of invasion (P<0.05).2 The expression of PCNA:The positive rate of PCNA in normal esophageal tissue was 8.16%, and in esophageal squamous cell carcinoma tissue was 69.39%. There was a statistical difference. The positive rates of PCNA in esophageal squamous cell carcinoma tissue with lymph node metastasis or not were 94.74% and 53.33%. The positive rates of PCNA in high-middle and low differentiated carcinoma tissue were 58.33% and 100.00%. The positive rates of PCNA in esophageal squamous cell carcinoma tissue accompanied by fibrous membrane invasion and non fibrous membrane invasion were 90.00% and 55.17%. The positive rates of PCNA on different TNM stage (Ⅰ,ⅡandⅢ) of esophageal carcinoma was 20.00%,67.74% and 92.31% respectively. The positive rate of PCNA was uncorrelated with gender and age. The positive rate of PCNA was correlated with degree of differentiation, TNM stage, lymph node metastasis and depth of invasion (P<0.05).3 The expression of MDM2:The positive rate of MDM2 in normal esophageal tissue was 22.45%, and in esophageal squamous cell carcinoma tissue was 55.10%. There was a statistical difference. The positive rates of MDM2 in esophageal squamous cell carcinoma tissue with lymph node metastasis or not were 84.21% and 36.67%. The positive rates of MDM2 in high-middle and low differentiated carcinoma tissue were 44.44% and 84.62%. The positive rates of MDM2 in esophageal squamous cell carcinoma tissue accompanied by fibrous membrane invasion and non fibrous membrane invasion were 75.00% and 41.38%. The positive rates of MDM2 on different TNM stage (Ⅰ,ⅡandⅢ) of esophageal carcinoma was 20.00%,45.16% and 92.31% respectively. The positive rate of MDM2 was uncorrelated with gender and age. The positive rate of MDM2 was correlated with degree of differentiation, TNM stage, lymph node metastasis and depth of invasion (P <0.05).4 The expression of p53:The positive rate of p53 in normal esophageal tissue was 12.24%, and in esophageal squamous cell carcinoma tissue was 61.22%. There was a statistical difference. The positive rates of p53 in esophageal squamous cell carcinoma tissue with lymph node metastasis or not were 84.21% and 46.67%. The positive rates of p53 in high-middle and low differentiated carcinoma tissue were 52.78% and 84.62%. The positive rates of p53 in esophageal squamous cell carcinoma tissue accompanied by fibrous membrane invasion and non fibrous membrane invasion were 80.00% and 48.28%. The positive rates of p53 on different TNM, stage (Ⅰ,ⅡandⅢ) of esophageal carcinoma was 0.00%,61.29% and 84.62% respectively. The positive rate of p53 was uncorrelated with gender and age. The positive rate of p53 was correlated with degree of differentiation, TNM stage, lymph node metastasis and depth of invasion (P<0.05). 5 Correlation analysis:The expression of PCNA had positive correlation with that of E2F-1, MDM2 and p53 in esophageal squamous cell carcinoma. The correlation coefficient was 0.308,0.424 and 0.355 respectively. The expression of E2F-1 had positive correlation with that of MDM2 in esophageal squamous cell carcinoma. The correlation coefficient was 0.455. There is no obvious correlation between E2F-1 and p53, and no obvious correlation between MDM2 and p53.Conclusions1 E2F-1, PCNA, MDM2 and p53 were overexpressed in esophageal squamous cell carcinoma. The results showed that they played an important role in the occurrence of esophageal squamous cell carcinoma.2 The expression of E2F-1, PCNA, MDM2 and p53 correlated with the aggression, TNM stage, degree of differentiation and lymph node metastasis of esophageal squamous cell carcinoma. They did not correlate with gender and age.3 E2F-1, PCNA, MDM2 and p53 had synergistic effect on the occurrence and development of esophageal squamous cell carcinoma.