Immunohistochemical Evaluation of Protein P16 Expression in Ovarian Germ Cell Tumors.

Ovarian germ cell tumors (OGCTs) constitute 10% of ovarian tumors in Egypt and mainly affect young females. Teratomas are the most common type.Most of teratomas is benign. However, it is liable for malignant transformation. Others are malignant including dysgerminoma, immature teratoma, yolk sac tumor,.etc and accounts 1-1.5% of cancers in young females. The pathogenesis of OGCTs is not clearly understood.

P16 is a member of cyclin-dependent kinase (CDK) inhibitors. It arrests the cell cycle in G1 phase, so it is known as a tumor suppressor protein.P16 immunohistochemical(IHC) expression has been widely investigated in different cancers. Its IHC expression is either absent or overexpressed. Overexpression of p16 is documented in Human Papilloma Virus related endocervical neoplasms and High grade squamous intraepithelial lesions of the vulvovaginal region.Absence of p16 expression is detected in multiple cancers such as Lung cancer, colorectal cancer and lymphoma.

P16 IHC expression in OGCTs is poorly investigated. One study suggests that absent p16 is involved in proliferation of malignant OGCTs via molecular assessment.Another study suggested that decrease P16 is involved in malignant transformation of Mature cystic teratoma to squamous cell carcinoma.However, Previous studies are still limited and recommended further studies to confirm its results.

As the role of altered P16 protein in OGCTs is not widely investigated, we hypothesized that abnormal P16 expression may be involved in its pathogenesis and germ stem cell proliferation.This will give more information about molecular pathways of germ stem cell proliferation to give a hope for CDK inhibitors as novel target therapies in the management of OGCTs.