BACKGROUND: A family member of Cyclin Dependent Kinase (CDK) inhibitors named P27kip1 has key position in cell cycle regulation, leading to arrest of cell proliferation. It enables a repair process of DNA damage through inhibition of different CDKs and therefore control the cell cycle by balancing the activity of CDKs. Changes in P27kip1expression which can be shown by (immunohistochemistry) can alter the normal progression of the cell cycle and its reduced expression has been shown in some tumors. Cyclin D1 also indirectly promotes cell proliferation by sequestering p21 and P27kip1, leading to the activation of CDK2. The present study aims at investigating the expression of P27kip1 and cyclin D1 proteins in selected benign lesions (pleomorphic adenoma, warthin’s tumor) and mucoepidermoid carcinoma and their possible correlation with clinicopathologic features.
PATIENTS AND METHODS: Clinicopathological features of 50 patients (30 MEC-10 PA, 10 warthin’s tumors), including age, sex and tumor size were obtained from medical records in the period 2009-2013, from files of pathology department, faculty of medicine- Benha University and Egyptian national cancer institute (NCI). Cases of MEC graded into 18 low grade, 12 intermediate and high grade. Stages (16 cases of stage I,II and 14 cases of stage III, and IV). Immunohistochemical staining with P27kip1 and cyclin D1 was performed for each specimen.
RESULTS: This study revealed: Highly statistical significant difference in P27kip1 expression between PA, warthin’s tumor & MEC. Inverse statistical significant correlation between P27kip1 expression and tumor stage. High inverse statistical significant correlation between P27kip1 expression and tumor grade. Inverse correlation between P27kip1 expression and age, tumor size and nodal status but with no statistical significance. High statistical significant correlation between cyclin D1 expression and tumor size, nodal status, stage, tumor grade and P27 expression. Insignificant difference in cyclin D1 expression between PA, warthin’s tumor and MEC. Significant difference in cyclin D1 expression between males and females.
CONCLUSION: In summary, our results provide evidence that reduced expression of P27kip1 may be involved in initiation, clinical progression and poor prognosis of MEC patients. Also, our findings indicate that cyclin D1 overexpression may play a pivotal role in the biological behavior of MEC and may provide a strong prognostic implication
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