Frequent p16INK4 (MTS1) gene inactivation in testicular germ cell tumors.

The molecular mechanisms responsible for the development of testicular germ cell tumors (GCTs) have not as yet been elucidated. The aim of the present study was to determine whether genetic alterations of p16INK4 (MTS1) and/or cyclin-dependent kinase 4 (CDK4) occur in the genesis of these tumors. We have analyzed these two genes in 29 testicular GCTs, seminomas, and nonseminomas. None of the tumors showed either p16INK4 or CDK4 mutations. Only 1 of the 29 GCTs displayed loss of heterozygosity of the p16INK4 gene. No homozygous deletions of p16INK4 were detected. Evidence of hypermethylation of p16INK4 exon 1, however, was demonstrated in 13 of the 26 (50%) GCTs analyzed. Tumor samples having exon 1 of p16INK4 methylated expressed significantly lower levels of p16INK4 mRNA, as analyzed by reverse transcriptase polymerase chain reaction. These results suggest that p16INK4 inactivation plays a role in the genesis of GCTs.

Simultaneous double immunoenzymatic labeling: a new procedure for the histopathologic routine.

We developed a new procedure for simultaneous immunohistoenzymatic double labeling that uses two mouse monoclonal antibodies of different isotypes or two antibodies from different species. The technique is a combination of the alkaline phosphatase-antialkaline phosphatase, avidin-biotin, and digoxigenin methods and uses horseradish peroxidase and alkaline-phosphatase detection systems. This standardized procedure can be carried out easily in the routine of a pathology laboratory and performed in parallel with single-antigen immunostaining, without the need for extra material or additional time for the laboratory technicians. This method can be applied to the detection of antigens localized in distinct cells or subcellular compartments and to the covisualization of different components from the same subcellular compartment.

[Value and limits of the determination of carcinoembryonic antigen (CEA) in postoperative evaluation of patients with colonic and rectal carcinomas]. / Utilité et limites du dosage de l'antigène carcinoembryonnaire (CEA) dans la surveillance postopératoire de malades atteints de carcinomes du côlon et du rectum

An attempt is made to define the usefulness and limitations of carcinoembryonic antigen (CEA) radioimmunoassay for evaluation of tumor resection and detection of tumor relapse in patients with large-bowel carcinoma. In 45 patients for whom complete tumor resection was reported, all but 5 showed a drop in CEA to normal values after surgery. The 5 patients whose CEA did not fall to below 5 ng/ml showed a subsequent rise in CEA level and later were all found to have a tumor relapse. The results indicate that an incomplete drop in circulating CEA level one month after surgery is a bad prognostic sign. Twenty-two of these patients were followed up by repeated CEA radioimmunoassay for several months after surgery; 8 showed a progressive increase in CEA levels preceding clinical diagnosis of tumor relapse by 2-10 months. The clinical history of these 8 patients is briefly described. The results demonstrate that relapses of colon and rectum carcinoma can be detected by increased CEA levels months before the appearance of any clinical evidence.

Detection of recurrence of large-bowel carcinoma by radioimmunoassay of circulating carcinoembryonic antigen (C.E.A.).

The usefulness and limitations of the carcinoembryonic antigen (C.E.A.) radioimmunoassay for the evaluation of tumour resection and for the detection of tumour relapse were studied in patients with large-bowel carcinoma. The level of plasma-C.E.A. was determined before any treatment in a group of 101 patients with histologically proven adenocarcinoma of the colon and rectum. 71% of all patients and 63% of cases with localised tumour (Dukes A and B) had a preoperative C.E.A. value of 5 ng. per ml. or higher. This limit was reached by only 1 of 90 apparently healthy, non-smoking blood-donors. Among 45 patients for whom a complete tumour resection was reported, all patients except 5 showed a drop of C.E.A. to normal values after surgery. The 5 patients whose C.E.A. did not fall to below 5 ng. per ml. showed a subsequent rise in C.E.A. level and were all found later to have a tumour relapse. The results indicate that an incomplete drop of circulating C.E.A. level one month after surgery has a bad prognostic significance. 22 of these patients were followed up by repeated C.E.A. radioimmunoassay for several months after surgery. 8 showed a progressive increase in C.E.A. levels preceding clinical diagnosis of tumour relapse by two to ten months. 6 other patients showed a moderate increase in C.E.A. levels, suggesting a tumour relapse not yet clinically detectable. The remaining 8 patients showed no increase in C.E.A. level above 5 ng. per ml. and no clinical symptoms of relapse. The results demonstrate that relapses of colon and rectum carcinoma can be detected by increased C.E.A. levels months before the appearance of any clinical evidence.