Immunohistochemical Expression of Survivin and γ-H2AX in Vulvar Intraepithelial Neoplasia and Low-Stage Squamous Cell Carcinoma

Abstract

Survivin inhibits apoptosis and is involved in the regulation of cell cycle progression and in the mitotic spindle formation. It is overexpressed in many cancers. The histone γ-H2AX is a marker of activated DNA damage and is overexpressed in different cancers and their precursor lesions. It also forms early during apoptosis. Eighty-seven formalin-fixed, paraffin-embedded archival vulvar tissues originating from 55 preoperatively untreated patients were immunostained with antibodies to survivin and γ-H2AX to determine their expression in normal squamous vulvar epithelia (NE, n=25), lichen sclerosus (n=10), high-grade classic vulvar intraepithelial neoplasia (n=16), differentiated vulvar intraepithelial neoplasia (n=16), and vulvar invasive keratinizing squamous cell carcinoma (ISCC, n=20; FIGO Ib). Immunostaining for both factors was scored for moderate and strong intensities with regard to quantity. Statistical analysis was performed by the χ test and Fisher exact test. Nuclear surviving expression increased from NE and lichen scleros to high-grade classic vulvar intraepithelial neoplasia, differentiated vulvar intraepithelial neoplasia, and ISCC significantly (P=0.0001) and followed the distribution of immature squamous epithelial cells. Positive scores for γ-H2AX were found in nuclei of cells in all diagnostic cohorts, in any epithelial level with some accentuation in the upper layers, was seen in pycnotic nuclei in horn pearls of ISCC and apoptotic bodies, without relevant statistical distributions. Immunoscores did not differ between grade 1 and grades 2/3. Expression patterns were different for both factors, suggesting their involvement in different biologic mechanisms as an early event leading to resistance to apoptosis in vulvar carcinogenesis.