Approximately 15% of colorectal cancers exhibit instability of short nucleotide repeat regions, microsatellites. These tumors display a unique clinicopathologic profile and the microsatellite instability status is increasingly used to guide clinical management as it is known to predict better prognosis as well as resistance to certain chemotherapeutics. A panel of five repeats determined by the National Cancer Institute, the Bethesda panel, is currently the standard for determining the microsatellite instability status in colorectal cancer. Recently, a quasimonomorphic mononucleotide repeat 16T/U at the 3' untranslated region of the Ewing sarcoma breakpoint region 1 gene was reported to show perfect sensitivity and specificity in detecting mismatch repair deficient colorectal, endometrial, and gastric cancers in two independent populations. To confirm this finding, we replicated the analysis in 213 microsatellite unstable colorectal cancers from two independent populations, 148 microsatellite stable colorectal cancers, and the respective normal samples by PCR and fragment analysis. The repeat showed nearly perfect sensitivity for microsatellite unstable colorectal cancer as it was altered in 212 of the 213 microsatellite unstable (99.5%) and none of the microsatellite stable colorectal tumors. This repeat thus represents the first potential single marker for detecting microsatellite instability.
No decade has seen as great advances as the 1970's in the understanding of cancer and in treatment results. The discovery of the role of oncogens, of some viruses, carcinogenic chemicals, and life-style in carcinogenesis and the increased cure rates in childhood tumors, leukemias, lymphomas, and breast and testicular carcinomas are some examples. The National Cancer Act must be credited for these advances to an appreciable degree.
The expression of the 17 beta-hydroxysteroid dehydrogenase (17-HSD) gene in a series of human breast cancer cell lines was studied by Northern blot hybridization with a cDNA probe and by a time-resolved immunofluorometric assay using polyclonal antibodies against the enzyme protein. The 17-HSD enzyme protein concentration was measured in the 800 x g cell extract. A high concentration was measured in the BT-20 cell line, corresponding to one-fourth of the average concentration in placental tissue. Western blot analysis indicated that the antigen corresponded to a single Mr 35,000 band. In 2 other cell lines (MDA-MB-361 and T-47D), the 17-HSD protein concentration was much lower, but still measurable, whereas in the remaining 5 cell lines (HBL-100, MCF-7, MDA-MB-231, MDA-MB-468, and ZR-75-1) it was below the detection limit of the assay. Treatment of the cells for 5 days with the synthetic progestin, ORG2058, resulted in an increase of the 17-HSD protein concentration only in the T-47D cell line. By Northern blot analysis, a low level of 2.3-kilobase mRNA transcripts was detected in all 8 cell lines. In addition, a 1.3-kilobase 17-HSD mRNA was present in the samples from the 3 cell lines containing measurable amounts of 17-HSD protein in the cell extract, and the band intensities were proportional to the amount of protein measured with the immunofluorometric assay. Only in the T-47D cell line did progestin treatment correspond to an increased amount of the 17-HSD 1.3-kilobase mRNA. These results suggest that the 1.3-kilobase mRNA for 17-HSD is the form most closely associated with protein expression and is also the only form responding to the progestin induction of the 17-HSD gene.
Uncertainty exists whether the 4154delA mutation of the BRCA1 gene detected in unrelated individuals from Latvia, Poland and Russia is a founder mutation with a common ancestral origin. To trace back this problem we analysed the mutation-associated haplotype of the BRCA1 intragenic SNPs as well as intragenic and nearby STR markers in mutation carriers from the aforementioned populations. The mutation-associated SNP alleles were found to be "T-A-A-A-A-G" for six intragenic SNPs of the BRCA1 gene (IVS8-58delT, 3232A/G, 3667A/G, IVS16-68A/G, IVS16-92A/G, IVS18+66G/A, respectively). The alleles 195, 154, 210 and 181 were found to be associated with the 4154delA mutation for STR markers D17S1325, D17S855, D17S1328 and D17S1320, correspondingly. Further analysis of markers in the 4154delA mutation carriers from all three populations allows us to assert that all analysed mutation carriers share a common ancestry.
Human epidermal growth factor receptor 2 expression in osteosarcoma and its relationship to prognosis have been the subject of several conflicting reports, most of them relying on immunohistochemical studies. Because the urgent need of prognostic markers and effective new treatment options for osteosarcoma patients, we evaluated the role of human epidermal growth factor receptor 2 in 2 well-characterized sets of pretherapeutic osteosarcoma samples (46 paraffin-embedded and 46 fresh-frozen biopsy samples) using immunohistochemistry with 2 different antibodies [DAKO A0485 (Glostrup, Denmark) and Novocastra CB11 (Newcastle, UK)] as well as fluorescence in situ hybridization, real-time polymerase chain reaction, and SNP array analyses and correlated our findings with clinicopathological parameters. However, our study failed to detect unequivocal evidence of human epidermal growth factor receptor 2 gene amplification or overexpression of human epidermal growth factor receptor 2 messenger RNA or protein in any of the investigated tumors. Only in a small subset of samples, a moderate increase in messenger RNA levels (13.6%) or focal membranous immunoreactivity (8.7%; A0485) was detected but did not correlate with survival or response to chemotherapy. Cytoplasmic staining was identified more frequently (63%; CB11) but again did not show any association with clinicopathological parameters. In conclusion, our study does not support a role for human epidermal growth factor receptor 2 as a prognostic marker in osteosarcoma.
We investigated aberrant p53 expression in 81 cases of cervical intra-epithelial neoplasias (CIN) using a polyclonal antibody CM-1. The presence of human papillomavirus (HPV) DNA was evaluated by in situ and dot blot hybridization. Significant (more than 1% of cells positive) p53 positivity was found in three cases (4%) of which only one contained HPV DNA. In an additional nine cases, occasional p53 staining was found in basal epithelial cells, frequently associated with epithelial hyperplasia and increased subepithelial inflammation. The results show that aberrant p53 expression is an infrequent finding in CIN lesions. It can be seen in lesions both with and without HPV infection. Most importantly, there was no p53 expression in most cases of HPV-negative CIN, suggesting that p53 inactivation is not an obligatory step in the development of cervical dysplasia. However, our findings do not exclude the possibility that p53 mutations can occur later in the course of cervical carcinogenesis.
Mutations of the tumor-suppressor gene p53 are common in epithelial tumors. Clonal mutations of p53 have been found in cervical and vulvar carcinomas negative for human papillomavirus (HPV), though at least in cervical cancer HPV infection and p53 mutations are not mutually exclusive. We have previously shown that about 40% of male genital warts and bowenoid papulosis lesions exhibit immunohistochemically detectable aberrant p53 protein, irrespective of the presence of HPV DNA. We studied p53 mutations in exons 4-8 with SSCP and sequencing in 13 male patients with 1 to 3 therapy-resistant genital warts or intra-epithelial neoplasias each and in 4 patients with penile squamous cell carcinoma. Thus, 13 genital warts, 6 bowenoid papulosis, 1 Queyrat's erythroplasia and 1 carcinoma in situ were studied. p53 protein was detected immunohistochemically, and HPV status was analyzed with DNA in situ hybridization and amplification of HPV-specific DNA. There was no correlation between p53 protein expression and HPV status. No mutations in exons 5-8 of the p53 gene were found in any of the lesions, and furthermore, no exon 4 mutations were found in lesions positive in p53 immunohistochemistry. In conclusion, overexpression of p53 does not indicate a p53 mutation in male genital warts, pre-malignant lesions or malignant squamous cell carcinomas. Our study thus suggests that p53 mutations are not important, or at least not early, events in male genital carcinogenesis.