Expression and implication of p63,p53 and PCNA in lung cancers

Objectives To study the expression of p63,a new member of p53 family,and p53,PCNA in 4 types of lung cancers and to gain an insight into their biological significance in carcinogenesis of lung neoplasms.Methods One hundred and eighty-three formalin-fixed,paraffin-embedded specimens of lung cancers and 30 matched surrounding tissue specimens as control were examined for p63,p53 and PCNA protein expression by immunohistochemistry using tissue microarray.Results In lung squamous cell carcinoma(SCC),adenocarcinoma(AC),bronchioloalveolar carcinoma(BAC) and small cell lung carcinoma(SCLC),the positivity of p63 was 82.1% (55/67),8.8%(7/80),4.2%(1/24) and 0(0/12);The positivity of p53 was 67.2%(45/67),44.8%(39/80),54.2%(13/24) and 41.7%(5/12) respectively.Its positivity in SCC was significantly higher than that in the other types(P0.05)and there was no significant difference between other types.PCNA was negative in 3.8%(7/183) of lung cancers,weakly positive in 31.1%(57/183),positive in 37.3%(69/183)and strongly positive in 27.3%(50/183).PCNA positivity in SCLC was significantly lower than that in other types(P0.05).Statistical results showed that the p63 positivity in SCC was significantly higher than that in the other three types(P0.01),but there was no correlation with the expression of p53,PCNA and clinicopathological characteristics,although the expression of p53 and PCNA was correlated with differentiation.Conclusion The results suggest that p63 plays a great role in carcinogenesis of lung SCC,and may help to distinguish squamous cell carcinomas from other three types of lung neoplasms in diagnostic pathology.