Expressions and localization of cyclin D1 and cyclin-dependent kinase inhibitor P27Kip1 in gliomas and meningiomas

Various studies have shown contradicting results in p27 and cyclin D1 protein expression and the association with brain tumors. This study was thus performed to address new information of both markers' expression in gliomas and meningiomas cases, among Malaysian brain tumors patients. For these purposes, 24 meningiomas and 23 gliomas were analyzed by immunohistochemistry and immunogold electron microscopy analyses to determine both protein expression and localization, respectively. From the results, we observed high expression level of p27 in all types of tumors including low and high grades of gliomas, and meningiomas. Our findings revealed that p27 was overexpressed in all cases including meningiomas (82.6%), low grades gliomas (80%) and high grades gliomas (84.6%). We subsequently found high level of cyclin D1 expression in meningiomas (70.8%), equal expression of cyclin D1 in low grades of gliomas, and the expression showed to decrease in higher malignancy of the cancer (76.9% as low expressors). Immunogold staining showed that p27 and cyclin D1 confined in nuclear and cytoplasm in both cancer types independently of survival of the patients (p27 miclocalization in meningiomas, p=0.6299; gliomas, p=0.2233 and cyclin D1 miclocalization in meningiomas, p=0.5627; gliomas, p=0.8230). Our results showed that elevation of p27 level did not inhibit proliferation of cancer cells. Via immunogold staining using electron microscopy technique, we have detected mislocalization of the p27 protein in cytoplasm of both meningiomas and gliomas cases which might cause the inactivation of the p27 protein.