The expression of p16 is not correlated with HPV status in CINI

Expression of geminin, p16, and Ki67 in cervical intraepithelial neoplasm and normal tissues

Geminin is a protein involved in cell cycle progression. We aimed to evaluate the diagnostic value of geminin expression in cervical intraepithelial neoplasm (CIN).The expression of geminin, p16, and Ki67 was examined in 95 samples, including CIN1 (n = 45), CIN2/3 (n = 40), and normal cervical tissues (n = 10) by immunohistochemistry. The correlation between geminin or p16 expression and human papillomavirus (HPV) status was also evaluated.Geminin expression was negative in all normal tissues and expressed in 13.3% of CIN1 and 90.0% of CIN2/3. P16 expression was demonstrated in 24.4% of CIN1 and 87.5% of CIN2/3. The corresponding Ki67 expression was 35.6% and 95.0%. The specificity of geminin for differentiating between CIN1 and CIN2/3 was 86.7%, while for p16 and Ki67 the corresponding values were 75.6% and 64.4%. The sensitivity of geminin, p16, and Ki67 was 90.0%, 87.5%, and 95.0%, respectively. The positive predictive value (PPV) and accuracy of geminin were higher than p16 and Ki67. In addition, geminin expression showed a weak correlation with HPV status, but there was no association between p16 expression and HPV status.These results suggested that geminin had a high degree of sensitivity and specificity in determining CIN2/3. In addition to p16 and Ki67, geminin might be used as a new biomarker to distinguish between CIN1 and CIN2/3.

Diagnostic utility of p16INK4a: a reappraisal of its use in cervical biopsies

p16(INK4a), an indirect marker of cell cycle dysregulation, is commonly expressed in cervical dysplasias and carcinomas associated with high risk human papillomavirus (HR-HPV) infections. Although p16(INK4a) immunohistology is routinely used as a cost effective surrogate marker, many of the published articles are confusing and contradictory. The discrepancies can be ascribed to a multitude of factors operating at the molecular, technical and interpretative levels. In the first place, our simplistic model of viral mediated oncogenesis is speculative and fails to account for all the known biomolecular changes. Unresolved technical issues include the variables of tissue fixation, antibody dilution, antibody isotype and clone, and the sensitivity of the particular detection method. Within any controlled staining method, strong diffuse or 'block' immunoreactivity in squamous cells may be found in moderate/severe dysplasia (CIN 2/3) and invasive squamous carcinoma. In contrast, focal or multifocal reactivity in squamous cells may be artefactual, related to low risk or HR-HPV. p16(INK4a) is less reliable when dealing with glandular lesions since considerable overlap exists between reactive and dysplastic lesions. In addition not all glandular dysplasias/carcinomas are HR-HPV related, nor are all p16(INK4a) immunoreactive lesions associated with HR-HPV. We conclude that p16(INK4a) immunoperoxidase shows greater specificity than sensitivity for squamous lesions; in comparison, glandular dysplasias/carcinomas show reduced specificity and sensitivity. Like all cell cycle regulatory proteins, the future diagnostic role of p16(INK4a) is limited. The ideal diagnostic molecular test for cervical dysplasias will detect a HR-HPV related product after, but not before, cell transformation and will reliably predict those cases yet to experience disease progression.