Key role for activin B in cellular transformation after loss of the von Hippel-Lindau tumor suppressor.

The von Hippel-Lindau tumor suppressor gene (VHL) is mutated in clear cell renal cell carcinomas (RCC), leading to the activation of hypoxia-inducible factor (HIF)-mediated gene transcription. Several VHL/HIF targets, such as glycolysis, angiogenesis, cell growth, and chemotaxis of tumor cells, have been implicated in the transformed phenotype of RCC-regulating properties. Here, we show that VHL suppresses key features of cell transformation through downregulation of the HIF-dependent expression of activin B, a member of the transforming growth factor beta superfamily. Activin B expression is repressed by restoration of VHL in VHL-deficient RCC cells and upregulated by hypoxia. RCC tumor samples show increased expression of activin B compared to that in the normal kidney. VHL increases cell adhesion to the extracellular matrix, promotes cell flattening, and reduces invasiveness. These effects are completely phenocopied by RNA interference-mediated knockdown of activin B and reverted by treatment with recombinant activin B. Finally, knockdown of activin B reduces tumor growth of RCC cells in nude mice. Our data indicate that activin B is a key mediator of VHL/HIF-induced transformation in RCC.

Polymorphisms of human androgen receptor (hAR) gene in prostate cancer cell lines PC-EW and PC-OR.

BACKGROUND: Prostate cancer is the leading tumor of the male in Western societies. Genetic alterations of the androgen receptor gene are known in the advanced metastatic disease. In this study, the androgen receptor gene was tested in two human prostate cancer cell lines, the androgen-sensitive PC-EW and the androgen-independent PC-OR. MATERIALS AND METHODS: Genomic DNA was isolated from two cell lines from metastatic prostate adenocarcinoma in heterotransplanted male athymic nude (nu/nu) Balb/c mice. Mutation screening was performed by sequencing of exons 1-8 of the human androgen receptor gene. RESULTS: Despite two polymorphisms found in the transactivation domain of hAR exon 1, no point mutations were detected in the hAR gene of both cell lines. CONCLUSION: Point mutations of hAR are not necessary for metastatic prostate cancer, while alterations in the solyglutamine and polyglycine repeat region in exon 1 of the MR gene are more often found. These repeats are two of many genetic influences that contribute to the overall risk of developing prostate cancer.

Polymorphisms in the human progesterone receptor (PGR) gene of two human prostate adenocarcinoma cell lines.

BACKGROUND: The incidence and mortality rate of prostate cancer has been steadily increasing in most countries worldwide. A potential implication of the progesterone receptor has been reported in prostatic carcinogenesis. In this study, an allele of human progesterone receptor gene (PROGINS), which was demonstrated to be associated with an increased risk of sporadic ovarian cancer, was tested in two human prostate cancer cell lines, PC-EW and PC-OR. MATERIALS AND METHODS: Genomic DNA was isolated from the cell lines in athymic nude mice. The polymorphisms in exon 4 and exon 5 and the insertion in intron G (PROGINS) were identified by sequencing and gel electrophoresis. RESULTS: The PROGINS allele and the polymorphisms in exon 4 and exon 5 were found heterozygous in the PC-OR cell line but not in the PC-EW cell line. CONCLUSION: We described the polymorphisms of exon 4, exon 5 and PROGINS in prostate cancer. Mutation screening of the PGR gene may provide information for risk assessment of developing prostate cancer.

Heterogeneity in prostate cancer: prostate specific antigen (PSA) and DNA cytophotometry.

BACKGROUND: The heterogeneity in prostate cancer is the reason for the difficult diagnosis and prognosis of this tumor. In this study, we looked for a correlation between prostate specific antigen (PSA), tumor staging and DNA cytophotometry. MATERIALS AND METHODS: Twenty-two prostates (pT1-T4) from patients with prostate cancer, who underwent radical prostatectomy, were examined. Preoperative PSA and postoperative DNA image cytometry, after 2-8 needle biopsies out of each organ, were evaluated. RESULTS: The prostate cancer tissues showed, in DNA stemline-interpretation according to Fu, in homogenous diploid tumors an average PSA level of 3.8 ng/ml, and, in homogenous aneuploid tumors, a level of 14.0 ng/ml. Tumors with heterogeneous DNA patterns with a majority of aneuploidy had an average PSA level of 85.6 ng/ml, and heterogeneous tissues with a majority of diploidy a level of 10.9 ng/ml. CONCLUSION: Only the stemline-interpretation of Fu after DNA cytophotometry is efficient for diagnosis of prostate cancer, and allows prognostic statements of the disease.

Clinical aspects for the use of DNA image cytometry in detection of bladder cancer: a valuable tool?

The employment of DNA flow or image cytometry for oncological diagnostic procedures is favored because of its high correlation to tumor biological behavior. Prognostic statements and therapeutic strategies therefore are based on the high validity of DNA cytometric measurements. Using 151 bladder washings from patients suspected of bladder cancer for this study, we examined the clinical value of various common methods of DNA single cell (SCI) and stemline interpretations (SLI). Comparing the specificity and sensitivity of DNA image cytometry in detection of bladder tumors, we found 81 and 52%, respectively, for SCI of Boecking, 84 and 45% for SLI of Boecking, 61 and 58% for SLI of Fu, and 82 and 40% for conventional stemline interpretation. To improve diagnostic and prognostic validity of DNA image cytometry, we designed our own method of interpretation. In consequence, we identified six single DNA parameters out of all recorded measurements that correlated most to histopathological grading (G1-G3). Creating reference values at random and rating by points, we used a cytometric grading system for ranking. In detection of bladder cancer specificity and sensitivity ultimately arrived at almost 70% in application of our method. Thus, by this study, we were able to show that sensitivity of DNA examination can be increased by combining various DNA parameters. Apart from our own scheme, the discrepancy in interpretation of DNA image cytometry does not allow us to recommend this procedure as the only diagnostic in detection of bladder cancer. However, in regard to prognostic statements, particularly tumor biological behavior, DNA image cytometry appears to be useful.