In a search for molecular markers of progression in prostate cancer by means of di erential display, we have identi®ed a new gene, which we have designated PTOV1. Semiquantitative RT ± PCR has established that nine out of 11 tumors overexpress PTOV1 at levels signi®cantly higher than benign prostatic hyperplasia or normal prostate tissue. The human PTOV1 protein consists almost entirely of two repeated blocks of homology of 151 and 147 amino acids, joined by a short linker peptide, and is encoded by a 12-exon gene localized in chromosome 19q13.3. A Drosophila melanogaster PTOV1 homolog also contains two tandemly arranged PTOV blocks. A second gene, PTOV2, was identi®ed in humans and Drosophila, coding for proteins with a single PTOV homology block and unrelated amino-and carboxyl-terminal extensions. A 1.8-Kb PTOV1 transcript was detected abundantly in normal human brain, heart, skeletal muscle, kidney and liver, and at low levels in normal prostate. Immunocytochemical analysis and expression of chimeric GFP-PTOV1 proteins in cultured cells showed a predominantly perinuclear localization of PTOV1. In normal prostate tissue and in prostate adenomas, PTOV1 was undetectable or expressed at low levels, whereas nine out of 11 prostate adenocarcinomas showed a strong immunoreactivity, with a focal distribution in areas of carcinoma and prostatic intraepithelial neoplasia. Therefore, PTOV1 is a previously unknown gene, overexpressed in early and late stages of prostate cancer. The PTOV homology block represents a new class of conserved sequence blocks present in human, rodent and¯y proteins. Oncogene (2001) 20, 1455 ± 1464.

PTOV1 is a mitogenic protein that shuttles between the nucleus and the cytoplasm in a cell cycle-dependent manner. It consists of two homologous domains arranged in tandem that constitute a new class of protein modules. We show here that PTOV1 interacts with the lipid raft protein flotillin-1, with which it copurifies in detergent-insoluble floating fractions. Flotillin-1 colocalized with PTOV1 not only at the plasma membrane but, unexpectedly, also in the nucleus, as demonstrated by immunocytochemistry and subcellular fractionation of endogenous and exogenous flotillin-1. Flotillin-1 entered the nucleus concomitant with PTOV1, shortly before the initiation of the S phase. Protein levels of PTOV1 and flotillin-1 oscillated during the cell cycle, with a peak in S. Depletion of PTOV1 significantly inhibited nuclear localization of flotillin-1, whereas depletion of flotillin-1 did not affect nuclear localization of PTOV1. Depletion of either protein markedly inhibited cell proliferation under basal conditions. Overexpression of PTOV1 or flotillin-1 strongly induced proliferation, which required their localization to the nucleus, and was dependent on the reciprocal protein. These observations suggest that PTOV1 assists flotillin-1 in its translocation to the nucleus and that both proteins are required for cell proliferation.PTOV1 was identified as a novel gene and protein during a differential display screening for gene expression in prostate cancer (4). PTOV1 is overexpressed in 71% of prostate carcinomas and in 80% of samples with prostate intraepithelial neoplasia, while it its barely detectable in normal prostate epithelium (34). In an independent study, PTOV1 was also found to be one of the genes most discriminant between normal and carcinomatous prostate (44). This gene codes for a protein that consists of two highly related sequence blocks arranged in tandem that are conserved in humans, rodents, and flies (4). The PTOV domain does not resemble any other protein motif described so far. A PTOV domain is also present in another protein, PTOV2 (4), later identified as ARC92, a component of transcriptional coregulator multisubunit complexes (28). Recently, PTOV2/ARC92, renamed as ACID-1, has been identified as a critical protein of Mediator complexes for the recruitment of activators to the basal transcriptional machinery (26). We have used yeast two-hybrid screenings to search for interaction partners of PTOV1, yielding a specific interaction with the lipid raft-associated protein flotillin-1 (5). Lipid rafts are specialized membrane microdomains enriched in glycosphingolipids, cholesterol, and glycosylphosphatidylinositol-anchored proteins (36). It is now believed that lipid rafts represent a central feature of cellular organization crucial for membrane trafficking events and for specific signaling cascades (36). Ubiquitous markers of lipid rafts are proteins of the Reggie/flotillin family (36, 38). Reggie-1 and Reggie-2, whose human orthologues are flotillin-2 and flotillin-1, respectively, were originally ide...

Prostate adenocarcinoma is the second most prevalent cancer among males in Western countries, with an incidence that increases in direct proportion with age. A large body of evidence indicates that activation of the pathways regulated by androgen receptor plays a central role in the development and malignant progression of prostate cancer.

BACKGROUND. Anemia occurs as a comorbidity in from 80% to 85% of patients with myelodysplastic syndromes (MDS): It causes fatigue, increases transfusion needs, and reduces quality of life. Darbepoetin a (DA) is an erythropoiesis-stimulating protein (ESP) that is more highly glycosylated and has a longer half-life relative to recombinant human erythropoietin (rHuEPO), thus, allowing less frequent administration, increased convenience, and better compliance.METHODS. This retrospective analysis included 81 patients with MDS who were enrolled at 9 Spanish centers and who received once-weekly, subcutaneous DA (75-300 mg) for 16 weeks. RESULTS.Fifty-five percent of all patients (38 of 69 evaluable patients) achieved responses; 30.4% of were major responses, and 24.6% were minor responses; 64.7% of rHuEPO-naive patients and 45.7% rHuEPO-treated patients responded; and 43.2% had received previous rHuEPO. Most responses (65.8%) occurred at or before Week 8. The median age at diagnosis was 70 years (range, 38-87 years), the median age at the initiation of DA treatment was 75 years (range, 39-91 years), and 56.8% of patients were women. The median time from last ESP dose to DA initiation was 16.8 weeks (range, 0.0-159.0 weeks; <1 week in 53.1% of patients).According to the French-American-British classification system (n ¼ 81 patients), 39.5% had refractory anemia (RA), 46.9% had RA with ringed sideroblasts, 9.9% had RA with excess blasts (RAEB), 1.2% had RAEB in transformation, and 2.5% had chronic myelomonocytic leukemia. According to the International Prognostic Scoring System (n ¼ 47 patients), 55.3% of patients were in the low-risk group, and 36.2% of patients were in the intermediate-1-risk group. The median baseline hemoglobin level was 8.9 g/dL (range, 8.4-9.1 g/dL). The Starting DA dose was 75 mg per week in 3.7% of patients, 150 mg per week in 65.4% of patients, and 300 mg per week in 29.6% of patients (the dose was increased in 18.5% of patients and reduced in 9.9% of patients; median time to dose adjustment, 8 weeks). Five patients received granulocyte colony-stimulating factors. No DA-related adverse reactions occurred. CONCLUSIONS.In the current study, 55% of evaluable patients with MDS safely achieved an erythroid response.

Some human hormone-refractory prostate cancers have mutations in a critical regulatory domain of the HIF-1alpha protein. We believe that these mutations might enable expression of this protein under inappropriate conditions and contribute to the development of therapeutic resistance by the cancer cells. This hypothesis is currently being tested.