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In this study, we investigated immunohistochemically the expression of mdm-2 protein in 93 surgically resected bronchogenic carcinomas. The findings were correlated with p53 protein detection status and clinicopathologic data (histologic type, differentiation grade of the lesions, lymph node metastases, and smoking history of the patients). Thirty of the 93 immunohistochemically examined specimens were subjected to Northern blot and differential polymerase chain reaction analysis to look into the mechanism of mdm-2 overexpression. Finally, we studied the concordance between p53 immunohistochemical positivity and p53 gene alterations as assessed by the single-strand conformation polymorphism technique. Seventy-three (78%) and 67 (72%) of 93 carcinomas showed nuclear immunoreactivity for mdm-2 and p53 proteins, respectively. We observed a high degree of concordance (75%) between p53 mutations and p53 immunolabelling, which was even higher in the specimens with p53 positively in more than 50% of the cells (90%). Despite the high percentage of mdm-2 and p53 expression, the two molecules were simultaneously detected in 50 (54%) of 93 cases. Forty-two (84%) of the 50 cases were accompanied by p53 mobility shifts, which indicated mutations. Interestingly, statistical analysis revealed an almost significant correlation between the carcinomas with mdm-2/p53 coexpression and lymph node disease (P = 0.058), which indicated a possible "gain of function" phenotype. In addition, absence of reactivity for both proteins was statistically more frequent in the patients without lymph node disease (P = 0.006). The mdm-2-positive/p53-negative immunohistochemical profile was more often seen in adenocarcinomas (P = 0.003), especially in well-differentiated ones (P = 0.02), than in other histologic types of lung cancer, which suggested a p53-independent pathway of mdm-2 overexpression. Molecular analysis showed that mdm-2 overexpression was a consequence of increased transcription rather than of mdm-2 gene amplification. The smoking history of the patients was strongly related to p53 (P = 10(-4)) even in the group of adenocarcinomas (P = 0.012). No correlation was observed between cigarette consumption and mdm-2 immunoreactivity.

In this study, the expression of epidermal growth factor receptor (EGFr) and c-erb-B-2 was evaluated in 35 formalin-fixed, paraffin-embedded cases of transitional cell carcinomas of the urinary bladder (TCCs). EGFr and c-erb-B-2 expression was assessed with immunohistochemistry, and molecular analysis of the respective genes was performed with the differential polymerase chain reaction. The results were statistically analyzed in relationship to histologic grade, stage, and clinical outcome. Strong cytoplasmic expression of the EGFr using the polyclonal antibody Ab-4 was found in three (25%) Grade 2 and eight (67%) Grade 3 TCCs (P < 0.01). Two Grade 2 (17%) and 11 (92%) Grade 3 TCCs strongly expressed the anti-c-erb-B-2 Ab-3 antibody. None of Ta/T1 TCCs cases showed strong expression against EGFr, in contrast to c-erb-B-2 where two cases (18%) were found to express an intense immunosignal. Eleven (85%) T2/T3 cases showed strong positivity either against EGFr or c-erb-B-2 (P < 0.001). Eleven patients died within 12 months after the diagnosis, and all of them showed strong expression of EGFr and c-erb-B-2. Amplification of EGFr and c-erb-B-2 genes was identified in one (3%) and four (11%) TCCs cases, respectively. All patients with amplified genes died within 12 months from the date of diagnosis. Our results indicate that simultaneous expression of EGFr and c-erb-B-2 occurs in TCCs, is related to the histologic grade and the stage of the disease, and denotes aggressive biologic behavior.

The p53 locus on the short arm of chromosome 17 at 17p13.1 was examined for small genomic deletions and mutations in 23 formalin-fixed, paraffin-embedded cases of special types of breast carcinoma (six medullary, seven apocrine, five differentiated tubular, and five papillary). p53 mutations in the evolutionarily conserved exons 5-9 were detected in 11 cases (four apocrine, two papillary, two medullary, and three differentiated tubular), using the novel non-radioactive PCR-based Hydrolink mutation detection enhancement (MDE) method, and confirmed by direct sequencing of the PCR products. Missense mutations causing amino acid substitutions were evenly distributed among exons. One case of apocrine carcinoma showed a polymorphism at codon 213 (CGA-->CGG). Twelve out of 23 cases were found to express a strong nuclear signal against CM-1 and DO-7, two anti-p53-specific antibodies. Small genomic deletions in the vicinity of the p53 locus were detected in 11 tumours (three papillary, three differentiated tubular, two medullary, and three apocrine carcinomas), using the multiplex PCR method. No statistical correlation was found between deletions at 17p13.1 and p53 mutations (P < 0.5). In addition, p53 mutations and immunoexpression correlated with the c-erbB-2 gene product, an oncogenic protein that has been implicated in cell cycle control (P < 0.001). Our findings suggest that genomic alterations of the p53 gene are quite common events associated with special types of breast carcinoma, particularly of the apocrine subtype, but the prognostic value is unlikely to be of clinical importance.