Clin Cancer Res
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We assessed the ability of cryptophycin 52 (LY355703), a novel antimicrotubule, to induce growth arrest and apoptosis in prostate cancer cell lines and investigated potential molecular mechanisms of death. LNCaP (androgen-dependent) and DU-145 (androgen-independent) cells accumulated in G(2)-M phase of the cell cycle and progressively acquired sub-G(0)-G(1) DNA content after 48 h of exposure to cryptophycin 52 (1-10 pM). Induction of apoptosis was confirmed by DNA ladder formation and detection of cytoplasmic nucleosomes. ⋯ A sustained increase in c-Jun NH(2)-terminal kinase phosphorylation was also observed, the levels of which strongly correlated with apoptosis. We conclude that apoptosis induced by cryptophycin 52 in prostate cancer cells is androgen status independent, cell type specific for caspase requirement, modulated by the bcl-2 family, linked to but not dependent on p53, and strongly correlated with c-Jun NH(2)-terminal kinase phosphorylation. Cryptophycin 52-induced apoptosis in prostate cancer cells is therefore associated with multiple cell line-specific alterations in apoptosis-associated proteins and pathways.
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Several studies to date have reported ovarian cancer risk due to inherited BRCA1 and BRCA2 mutations using familial data or population-based series of probands. Familial aggregation associated with both of these methods may result in a substantial ascertainment bias. To address this, we have used a case-control design that does not involve familial aggregation to estimate the lifetime penetrance of ovarian cancer due to BRCA1 and BRCA2 mutations. ⋯ The lifetime penetrances of BRCA1 mutations are lower than estimates obtained using familial data with multiple affected members but larger than estimates from some population-based proband series. The lifetime penetrance estimate of a BRCA2 mutation is in the range reported by some of the studies based on familial data. These results could have implications for clinical counseling, surgical interventions, and screening recommendations in women carrying these founder mutations.
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Osteosarcoma is an aggressive primary bone cancer characterized by expression of platelet-derived growth factor (PDGF) and its cognate receptor. Coexpression of the growth factor and receptor suggests their role in autocrine or paracrine growth mechanisms. It has been reported previously that STI571 has specific activity in inhibiting select tyrosine kinase receptors, including PDGF and c-Kit. Osteosarcomas express low levels of c-Kit but abundant levels of PDGF receptor (PDGFR). ⋯ Our data demonstrate that STI571 inhibits PDGF-mediated growth and leads to apoptosis of osteosarcoma cells in vitro by selective inhibition of the PDGFR tyrosine kinase. The effectiveness of STI571 in our studies suggests targeting of PDGFRs as a novel treatment for osteosarcoma.
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We recently demonstrated the strong anticancer efficacy of silibinin,an active constituent of a widely consumed dietary supplement milk thistle extract, against human prostate cancer cells in culture and nude mice xenografts. We also observed that pharmacologically achievable concentrations of silibinin in animal studies were in the range of 25-100 microM, depending on the dose regimen, which did not show any apparent toxicity to the animals. In this study, we assessed whether silibinin synergizes the therapeutic potential of the chemotherapeutic drug doxorubicin against prostate cancer, the effectiveness of which is limited because of high systemic toxicity. ⋯ These findings suggest a need for in vivo studies with this combination in preclinical prostate cancer models. Positive outcomes might be relevant for a clinical application in prostate cancer patients.
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Altered and deregulated cyclin-dependent kinase (cdk) activity is now believed to play a major role in the pathogenesis of head and neck squamous cell carcinomas (HNSCC), thus providing a suitable cellular target for therapeutic intervention. UCN-01 (7-hydroxy-staurosporine), a known protein kinase C and cdk modulator, demonstrates antiproliferative and antitumor properties in many experimental tumor models and may represent a potential candidate to test in HNSCC. In this study, UCN-01 displayed potent antiproliferative properties (IC50 of approximately 17-80 nM) in HNSCC cells. ⋯ Terminal deoxynucleotidyl transferase-mediated nick end labeling staining of xenograft samples revealed a higher incidence of apoptosis in treated tissues when compared with control. Additional tissue analysis demonstrated that elevated p27(KIP1) with minimal increase in p21(WAF1) and reduced cyclin D3 levels were readily detected in those animals treated with UCN-01, similar to those observed in HNSCC cells. Thus, UCN-01 exhibits both in vitro and in vivo antitumor properties in HNSCC models, and these effects are associated with a decrease in cyclin D3 and an increase in p27(KIP1) protein levels, thus providing appropriate surrogate markers to follow treatment efficacy in vivo and, therefore, a suitable drug candidate for treating HNSCC patients.