p16INK4A and MIB-1: An immunohistochemical expression in preneoplasia and neoplasia of the cervix

Aim: To evaluate the potential of p16INK4A and MIB-1 and to compare the expression and interrelationship of these markers in cervical preneoplasias and neoplasias. Materials and Methods: Immunohistochemical analysis of p16 and MIB-1 was performed in n = 63 tissue sections and by matching the corresponding Papanicolaou smears. Staining intensity for p16 was determined using the 0-3 grading system. For MIB-1, labelling indices (LI) were calculated and grading was performed using the I-III scoring system. Results: No positive staining of p16 was observed in the normal cervical epithelium. With increasing severity of cervical intraepithelial neoplasias (CIN), the p16 expression increased progressively. Significant up-regulation of p16 was observed in carcinoma cervix. MIB-1 LI was observed to increase with increasing grades of CIN, and significant overexpression of MIB-1 was observed in carcinoma cervix. Correlation between grades of p16 and that of MIB-1 among cervical neoplasias showed an increasing p16 expression with consistently increasing MIB-1 LI in the groups of increasing severity. Conclusion: This pattern of overexpression of p16 and MIB-1 demonstrate their use as a diagnostic marker for cervical neoplastic lesion. Therefore, p16 and MIB-1 markers in tissue sections can be used as an adjunct to definitively diagnose preneoplastic and neoplastic lesions in the cervix.