BACKGROUND Colorectal cancer (CRC) is the second most common malignancy in the world. However, its mortality rate can be reduced if diagnosed early. P33ING1b is a tumor suppressor protein, which plays a role in growth control and apoptosis. Suppression of p33(ING1b) is associated with the loss of cellular growth control. However, p33 (ING1b) expression in CRC and its correlations with clinicopathological factors have been less studied. The aim of this study was to examine p33(ING1b) expression in patients with CRC and evaluate its potential correlations with clinicopathological factors. METHODS P33(ING1b) protein expression was examined in 70 cases of CRC tissue samples and their corresponding neighboring normal tissues by immunhistochemistry. Moreover, p33(ING1b) expression in CRC and its correlations with clinicopathological variables including patients' sex and age, tumor type, location, stage, and differentiation grade were examined. RESULTS P33(ING1b) expression was significantly lower in tumor samples compared with the normal adjacent samples (p<0.002). CONCLUSION Low expression of P33(ING1b) in patients with colorectal cancer, may be an important molecular event in the pathogenesis of colorectal cancer. Our data suggest that reduced expression of p33(ING1b) may be contribute to tumor genesis and accompanied by the loss of cellular growth control. In fact cell growth is out of control in lower expression of P33 and dysfunctional program cell death. P33 expression might explain the etiology of CRC for reducing the expression of tumor suppressor proteins.
Keywords: Clinicopathological factors; Colorectal Cancer; Immunhistochemistry.