Studies on the Expression of P16^INK4A mRNA in Cervical Dysplasias

ABSTRACT

Cervical cancer is caused by a persistent infection with high-risk human papillomavirus (hr-HPV). Accurate grading of premalignant precursor lesions, referred to as cervical intraepithelial neoplasia (CIN) is important for clinical management of patients. A promising candidate marker to identify high-grade CIN lesions is the cellular protein p16^INK4a, an indirect indicator of cell cycle dysregulation commonly expressed in cervical dysplasias and carcinomas associated with hr-HPV. Like other cell cycle regulatory proteins, the diagnostic role of p16^INK4A is still under consideration.

The aim of the current study was to investigate the expression of p16^INK4A mRNA by a quantitative reverse transcriptase PCR (qRT-PCR) in cervical specimens and evaluate the correlation between the p16^INK4A expression levels and the grade of CIN as well as hr-HPV genotypes. The qRT-PCR assay for the detection of p16^INK4A mRNA was developed and optimized. As an internal control, integrin gene was selected. The levels of p16^INK4A mRNA were investigated in 567 cervical specimens collected from women with confirmed cytological and/or histological diagnosis. The correlation between the p16^ink4A mRNA expression level and the grade of cervical cytological/histological alterations was statistically evaluated. The highest p16^ink4A mRNA expression level was observed in patients with high-grade cervical dysplasia. The lowest mRNA expression level was detected in cervical specimens collected from woman with normal Pap smears. To investigate the correlation between the levels of p16^ink4A mRNA and the particular HPV genotype the multiplex PCR was employed that alowed detection of 16 hr-HPV genotypes. The correlation analysis revealed that the oncogenic potential of HPV but not a particular HPV genotype is associated with the increased levels of p16^ink4A mRNA in cervical specimens.

Keywords:

• cervical dysplasia
• human papillomavirus
• p16^INK4A
• quantitative PCR