Expressions and significance of estrogen receptor and adaptor protein p66Shc in colon cancer

Background: Estrogen and estrogen receptor (ER) are considered to play important roles in the tumorigenesis and progression of colon cancer, however, the mechanism of ER in colon caner is still unclear. Adaptor protein p66Shc is upregulated by steroid hormones in hormone-sensitive cancer cells, which is correlated with the steroid hormone-stimulated cell proliferation. Aims: To investigate the expressions and significance of ER and p66Shc in colon cancer. Methods: Protein expressions of ER and p66Shc in 65 paraffin-embedded colon cancer tissue and the corresponding adjacent non-cancerous tissue were detected by immunohistochemistry. Correlation of p66Shc protein expression with the clinicopathological characteristics of colon cancer was analyzed. Results: Expressions of ER and p66Shc protein were located in nucleus and cytoplasm, respectively. Positivity rates of both ER and p66Shc protein were significantly higher in colon cancer tissue than in adjacent non-cancerous tissue (ER: 47.7% vs. 0%, P<0.01; p66Shc: 49.2% vs. 0%, P<0.01). Moreover, positive correlation was found between ER and p66Shc protein expressions (r=0.43, P<0.05). Expression of p66Shc protein had no correlation with gender, age, primary tumor location, tumor size, gross type, depth of tumor invasion, lymph node metastasis and AJCC stage, however, it was significantly correlated with histological grading of colon cancer (well differentiated: 22.2%, moderately differentiated: 47.7%, poorly differentiated: 75.0%, P=0.046). Conclusions: Colon cancer might be an estrogen-sensitive malignancy. Estrogen and ER might cooperate with p66Shc to play a role in the tumorigenesis and progression of colon cancer.