Immunohistochemical analysis of the nm23 gene products in testicular seminoma

Loss of heterozygosity of selected tumor suppressor genes in human testicular germ cell tumors

Human testicular germ cell tumors (TGCTs) are histologically heterogenous neoplasms with a variable malignant potential. Two main groups of germ cell tumors occur in men: seminomas and nonseminomas. In the present study, a set of four tumor suppressor genes was investigated in testicular cancers. CDH1, APC, p53, and nm23-H1 genes were tested for loss of heterozygosity (LOH). Thirty-eight testicular germ cell tumors (17 seminomas and 21 nonseminomas) were analyzed by PCR using restriction fragment length polymorphism or the dinucleotide/tetranucleotide repeat polymorphism method. An allelic loss of p53 at exon 4 was detected in five nonseminomas, whereas LOH of p53 at intron 6 occurred in one of the seminoma and two of the nonseminoma samples. Allelic losses of the APC gene were present in three seminomas and one nonseminoma, whereas one seminoma and three nonseminomas showed LOH of CDH1. The analysis of allelic losses showed no common structural genetic alterations in tumor tissues, although a different pattern of LOH was observed between the two main histological groups of TGCTs.

Semiquantitative immunoblot analysis of nm23-H1 and -H2 isoforms in adenocarcinomas of the lung: prognostic significance

Total amounts of nm23 protein and relative levels of H1 and H2 isoforms were studied in 27 fresh-frozen samples of pulmonary adenocarcinoma and adjacent non-neoplastic tissues that were obtained at surgery. Semiquantitative immunoblotting with a monoclonal antibody (Pan-242) against nm23 protein demonstrated both isoforms, recognized as 20.5 kDa for H1 and 18.5 kDa for H2, to be present in all cases. Both H1 and H2 levels in neoplastic tissues were higher than in the corresponding non-neoplastic samples. Expression of H2 was usually greater than of H1. The H2/H1 ratio varied from 1.9 to 14.1 (mean value 5.2) in non-neoplastic tissues and 1.0-5.9 (mean value 2.5) in neoplastic tissues, although this ratio did not correlate with any prognostic factor like tumor size, nodal status or distant metastasis (TNM tumor stage). H1 and H2 levels were significantly lower (mean values 4.3 and 2.4) in well-differentiated than in moderately and poorly differentiated adenocarcinomas (8.3 and 3.0) (P < 0.03 and P < 0.05, respectively). These data indicate that H1 and H2 isoform levels correlate with histological differentiation, but not the metastatic potential or stage of pulmonary adenocarcinoma.

nm23-H1 protein immunoreactivity in intraepithelial neoplasia and invasive squamous cell carcinoma of the uterine cervix

Differences in the immunohistochemical expression of the 17 kDa protein encoded by the human nm23-H1 gene were studied in premalignant lesions and invasive squamous cell carcinoma (SCC) (N = 8) of the cervix using routine streptavidin-biotin immunohistochemistry and a polyclonal antibody to the nm23-H1 protein. The premalignant lesions were koilocytic atypia due to wart virus infection (N = 5), low-grade cervical intraepithelial neoplasia (CIN) (N = 7) and high-grade CIN (N = 7). The carcinomas were either moderately (N = 3) or poorly differentiated (N = 5). The non-neoplastic controls were normal squamous epithelium from cases with uterine prolapse (N = 7) and normal squamous epithelium not affected by the infective or neoplastic areas of some of the cases with wart virus infection (N = 2) and carcinoma (N = 2). Moderate to strong cytoplasmic and, occasionally, nuclear immunostaining for the nm23-H1 protein was seen in all cells above the basal layer of the normal squamous epithelium. However, most of the cervical SCC show a relative reduction in nm23-H1 immunoreactivity (7/8 cases; 88%). This difference in nm23-H1 expression was statistically significant (P = 0.0006; Chi-squared test with continuity correction). All of the cases with wart virus infection (N = 5; 100%) displayed moderately strong nm23-H1 immunostaining throughout the squamous epithelium except for the basal layer where no staining was observed. The cases that had low-grade squamous dysplasia of the cervix (CIN I-II) (N = 7; 100%) also displayed moderate to strong nm23-H1 immunoreactivity in the epithelium except for the basal layer (CIN I) or the lower two-thirds of the epithelium (CIN II). nm23-H1 Immunoreactivity was either absent or was significantly reduced in all of the high-grade CIN (CIN III) cases (N = 7; 100%) in which only the non-dysplastic superficial third of the squamous epithelium displayed nm23-H1 immunolabeling. The difference in nm23-H1 expression between low-grade and high-grade CIN cases was statistically significant (P = 0.0013; Chi-squared test with continuity correction). Similarly, the difference between low-grade CIN and SCC cases in the expression of nm23-H1 was also significant (P = 0.0041; Chi-squared test with continuity correction). However, no statistically significant difference in nm23-H1 immunoreactivity was found between cases of high-grade CIN and SCC. In conclusion, nm23-H1 protein immunoreactivity is reduced in high-grade CIN and cervical SCC but not in low-grade CIN. These findings suggest that reduced expression of the protein may be important early in the sequential development of cervical squamous neoplasia.