1995 Volume 36 Issue 5 Pages 273-282
Immunohistochemical study on p53 overexpression was performed by pretreatment with microwave oven heating as antigen retrieval using anti-p53 monoclonal antibody (DO-7). The materials were forty-eight formalin-fixed, paraffin-embedded tissue sections of the resected human hepatocellular carcinomas (HCCs) during recent 15 months in my department.
Nuclear staining of p53 was positive in 12/48 (25.0%) by this microwave pretreatment, while none of them was stained without this pretreatment. The results of staining by this method were significantly correlated with those on fresh-frozen tissue sections stained by conventional method (p<0.0001).
The tumor sizes of all p53 overexpression cases with this method were more than 2cm in diameter. P53 was not overexpressed in massive type of HCCs, while positive rate of p53 overexpression was significantly higher in multinodular-fused type (p<0.05). Well-differentiated type of HCCs has no p53 overexpression, while moderately and poorly differentiated ones showed significantly higher positive rate of p53 overexpression (p<0.05). HCCs of positive HCV-Ab, vp and fc-inf factor showed higher positive rate of p53 overexpression comparing with those of negative ones. Aneuploid HCCs showed higher positive rate of p53 overexpression than diploid ones. And furthermore, positive rate of strong p53 overexpression was significantly higher in HCCs of PCNA Labeling Index (PCNA LI)≥40% than those of PCNA LI<40% (p<0.05).
Only a few cells were sporadically stained with p53 in 26 out of 36 cases of negative p53 overexpression group. In these 26 cases, immunohistochemical staining was performed with anti-LewisY (LeY) antibody (BM-1/JIMRO), which was a monoclonal antibody reactive to cells of apoptosis (programmd cell death) in the early stage of it. Then it was found that cells of positive cytoplasmic staining with BM-1/JIMRO were turned out to be identical or nearby to the cells of p53 overexpression in 22 cases (84.6%).
The results suggested that pretreatment of microwave oven heating in immunohistochemical staining of p53 was an effective antigen retrieval method in human HCC tissues and p53 overexpression shown by this method was seemed to be an useful marker of the biological malignant potentials of human HCCs. And more, p53 suggests to play a key role on induction of apoptosis in human HCCs.
