No abstract

Forty oral squamous cell carcinomas and 20 leukoplakias were examined for expression of p53 oncoprotein using an immunohistochemical technique with BP53-12 monoclonal antibody. Positive staining was found in 21/40 (52%) of the carcinomas and 2/20 (10%) of the leukoplakias. Furthermore, comparison of p53 expression with binding of PC 10 monoclonal antibody to proliferating cell nuclear antigen (PCNA) and degree of histological malignancy in terms of invasion and histological differentiation of carcinomas demonstrated a positive correlation in both cases.

The levels of estrogen receptors in human benign prostatic hypertrophy and in various pathological classifications of prostate carcinoma were assessed using immunohistochemical methods. All cases of benign hypertrophy showed elevated levels of estrogen receptor, while receptor-positive cells were detected in only 48% of carcinomas, indicating a negative correlation between receptor status and malignancy. Furthermore, the prognosis for effective endocrine therapy was poor in cases where tissues demonstrated low or negative receptor levels. In addition, the estrogen receptor status was compared to cell kinetic index such as proliferating cell nuclear antigen and argyrophilic staining of the nuclear organizer region.

Exons 1-3 of the p16/CDKN2 gene, exons 4-9 of the p53 gene and exons 1 and 2 of H-, K- and N-ras genes were screened for mutations by a combination of immunohistochemistry and single-strand conformational polymorphism (SSCP) analyses of polymerase chain reaction products from human surgical samples of both frank oral squamous cell carcinomas and premalignant lesions. The samples included 20 squamous cell carcinomas, 10 epithelial dysplasias and 10 epithelial hyperplasias. No identifiable gene mutations were detected in any of the dysplasias or hyperplasias, while 2 (10%) deletions and 2 (10%) mutations of p16/CDKN2, along with 5 (25%) p53 mutations were found in the advanced carcinomas, yielding characteristic p16/ CDKN2 and p53 changes. A mutation in the K-ras gene was found in single carcinoma and dysplastic samples. From the data, it can be argued that p16/CDKN2 and p53 mutations are relatively late occurrences in human oral tumorigenesis and that genetic alterations of the ras genes may not play a significant role in squamous neoplasia.

The nm23 gene products/nucleoside diphosphate (NDP) kinase expression in prostate carcinomas and benign hyperplasias was evaluated immunohistochemically. Monoclonal antibodies against nm23‐H1 and nm23‐H2 proteins were prepared using the corresponding proteins fused with glutathione S‐transferase as immunogens. Of the 80 cases of nonmetastatic prostate carcinoma examined, 74% (59/80) and 60% (48/80) were immunoreactive for nm23‐H1 or nm23‐H2 protein, respectively. Negative staining for nm23‐H1 occurred in 83% of metastatic lesions, while 34% were negative for nm23‐H2. All primary tumors corresponding to the metastases examined showed positive immunostaining for nm23‐H1, indicating an inverse relationship between expression of this protein and metastatic status. nm23‐H2 protein was detected in 83% of primary tumors and its expression appeared to he significantly correlated to the degree of histological differentiation. In contrast, all cases of benign prostatic hyperplasia showed elevated levels of both nm23‐H1 and nm23‐H2 expression. These data suggest that the nm23/NDP kinase may play a role in suppressing the expression of malignant potential in prostate carcinomas.