Interplay Between the Immunohistochemical Expression of P53 and the Proliferation Index in the Keratinocyte Tumors of the Skin

P53 is important for cell cycle regulation, and its overexpression is seen in malignant tumors. We examined correlation between p53 expression and cell proliferation, and its role in the pathogenesis of keratinocyte skin tumors. We used biopsies from patients with squamous cell carcinoma, actinic keratosis and keratoacanthoma. We examined crosssections stained with HE and using anti-cytokeratin, antip53 and anti-Ki67 antibodies.

Expression of p53 is found in 87, 85% of SCC, in 83. 3% of AK and 13. 4% KA. The high index of p53 expression was higher in SCC and AK compared to KA. We also observed a positive correlation between the expression of p53 and localization of the tumors. The largest proportion of subjects with AK and SCC has a high index of p53 expression on photoexposed region. We also observed that p53 expression correlates with age whereby in AK p53 expression increases with age. The high index of proliferation is most frequent in SCC and KA. Also at AK we found a strong correlation between a moderate proliferation index and tumor localization in photoexposed region. Between the proliferation index and p53 expression we observed a significant positive correlation only in SCC.

Proliferation index and the expression of p53 are useful for the differentiation of precursor keratinocyte lesions and skin carcinoma. High p53 expression has been associated with the aging and significantly correlates with the exposure to UV radiation in SCC and AK. High expression of p53 in AK and SCC supports the importance of this oncoprotein in carcinogenesis of the skin.