Expression of cell-cycle regulators p53, p27, and p21 in mucoepidermoid and adenoid cystic carcinomas of the minor salivary glands

Abstract

Expression of cell-cycle regulators p53, p27, and p21 in mucoepidermoid and adenoid cystic carcinomas of the minor salivary glands Iman M. TalaatBackground The orderly progression of cells through different phases of the cell cycle is orchestrated by various molecules and proteins. p53 plays a crucial role in stress response and tumor suppression. It is a unique cellular processor that integrates signals from various pathways in order to coordinate cell proliferation, differentiation, and apoptosis. p21 WAF1/CIP1 and p27 have key positions in cellcycle regulations, leading to arrest of cell proliferation. They enable a repair process of DNA damage. In several human tumors, a loss of these proteins is associated with poor clinical outcome. Despite recent progress in molecular medicine, there is still a paucity of data on the involvement of cell-cycle regulatory proteins in the pathogenesis of salivary gland tumors.Aim The present work was performed to assess the immunohistochemical expression of p53, p27, and p21 in 15 patients with mucoepidermoid carcinomas (MECs) and adenoid cystic carcinomas (ACCs) of the minor salivary glands and their possible correlation with histopathologic grading.Results The present study included eight patients with ACC and seven patients with MEC. Most of the ACC patients (62.5%) showed positive reaction for p53, whereas only 25% were immunoreactive to p21. Among the seven examined MEC patients, the overall expression of p53 was detected only in those with high-grade tumors. With respect to p21, a moderate reaction was detected in a patient with low-grade MEC. In contrast, immunoreactivity to the p27 protein was detected only in low-grade tumors.Conclusion The cell-cycle regulatory protein p53 was highly expressed in high-grade neoplasms, whereas the reverse was noticed in the case of p27. These findings have a strong prognostic impact. p21 overexpression may be a useful prognostic marker when evaluated in conjunction with p53 status.