1. ¹Istituto di Anatomia Patologica, Università Cattolica del Sacro Cuore, Rome, Italy
2. ²Centro di Ricerche Oncologiche 'Giovanni XXIII'—Istituto di Patologia Generale, Università Cattolica del Sacro Cuore, Rome, Italy
3. ³Dipartimento Misto di Anatomia Patologica e di Medicina Legale, Sezione di Anatomia Patologica, University of Modena and Reggio Emilia, Modena, Italy

Correspondence: Dr A Sgambato, MD, PhD, Istituto di Patologia Generale—Centro di Ricerche Oncologiche 'Giovanni XXIII', Università Cattolica del Sacro Cuore, Largo Francesco Vito 1, Rome 00168, Italy. E-mail: asgambato@rm.unicatt.it

^*Current address: Department of Medical Genetics, University of Antwerp, Campus Drie Eiken, Universiteitsplein 1, Antwerp B-2610, Belgium.

Received 22 June 2005; Revised 10 October 2005; Accepted 16 October 2005; Published online 10 February 2006.

Abstract

Vulvar cancer represents an important medical problem worldwide whose incidence is increasing at an alarming rate in young females. Several factors have been linked to vulvar cancer development, but its exact pathogenesis remains to be determined. Vulvar tumorigenesis proceeds through intermediate dysplastic lesions, known as vulvar intraepithelial neoplasias, frequently associated with non-neoplastic epithelial disorders of the vulva, such as lichen sclerosus and squamous cell hyperplasia. In this study, the expression of the CDK inhibitor p27^Kip1 and the extent of endogenous oxidative DNA damage were evaluated in vulvar specimens, including normal tissues, lichen sclerosus, squamous cell hyperplasia, vulvar intraepithelial neoplasias and invasive squamous cell carcinomas. We found that p27^Kip1 was constantly expressed in normal vulvar epithelium cells while a progressive significant reduction in the percentage of p27^Kip1-positive cells was observed in vulvar intraepithelial neoplasias (77%) and in invasive carcinomas (64%). Mean percentage of positive cells in invasive carcinomas, but not in vulvar intraepithelial neoplasias, was also significantly lower than squamous cell hyperplasia lesions (78%) while lichen sclerosus displayed a percentage of positive cells (45%) significantly lower than both vulvar intraepithelial neoplasias and invasive carcinomas. 8-hydroxydeoxyguanosine (8-OHdG) is considered a sensitive biomarker for oxidative stress. We observed a progressive significant increase in the levels of 8-OHdG and in the percentage of positive cells from normal vulvar epithelium to vulvar intraepithelial neoplasias (25%) and to invasive carcinomas (64%). Squamous cell hyperplasia displayed an intermediate percentage of positive cells comparable to vulvar intraepithelial neoplasias 2 but significantly higher than vulvar intraepithelial neoplasias 1 and lower than invasive carcinomas. Lichen sclerosus staining was significantly lower than carcinomas but higher than vulvar intraepithelial neoplasias and squamous cell hyperplasia. These results demonstrate that expression of p27^Kip1 is downregulated while oxidative DNA damage increases from early non-neoplastic epithelial alterations through vulvar intraepithelial neoplasias to invasive vulvar carcinomas. Thus, both parameters might play an important role in the development of this cancer and their study might contribute to our understanding of human vulvar carcinogenesis.