Development and characteristics of a human cell assay for screening agents for melanoma prevention.
ABSTRACT This paper describes the development and initial evaluation of a human cell assay to identify potentially efficacious agents for preventing melanoma. Four human cell lines were used: normal melanocytes, a radial growth-phase-like melanoma cell line (WM3211), a vertical growth-phase-like melanoma cell line (Lu1205), and 83-2c, a cell strain cloned from metastatic melanoma. Four endpoints were evaluated in ultraviolet B-treated cells: annexin V, human leukocyte antigen-DR; E-cadherin, and N-cadherin. Annexin V was induced by nimesulide, 4-hydroxyphenylretinamide, and difluoromethylornithine in ultraviolet-B-treated radial growth-phase-like melanoma cells. None of the agents inhibited human leukocyte antigen-DR expression in ultraviolet-B-treated radial growth-phase-like melanoma cells, the only cells that strongly expressed human leukocyte antigen-DR. E-cadherin was overexpressed only in radial growth-phase-like melanoma cells relative to melanocytes, and ultraviolet B exposure dramatically reduced this expression. E-cadherin was only induced by difluoromethylornithine in ultraviolet-B-treated radial growth-phase-like melanoma cells. N-cadherin was over- expressed in all melanoma cell lines relative to melanocytes. In this study, all candidate preventive agents inhibited N-cadherin in ultraviolet B-treated radial growth-phase-like melanoma cells. Four agents inhibited N-cadherin in ultraviolet B-treated vertical growth-phase-like melanoma cells. The mean ratios of N-cadherin to E-cadherin levels and specific endpoint responses for both the radial growth-phase-like melanoma and vertical growth-phase-like melanoma cells were used to rank the agents. Agents were evaluated at clinically relevant concentrations. The rankings were difluoromethylornithine>4-hydroxyphenylretinamide>nimesulide>9-cis-retinoic acid>polyphenon E. Diphenylhydramine, D-mannitol, and nordihydroguaiaretic acid were inactive. The results of these initial studies suggest that ultraviolet-B-treated radial growth-phase-like melanoma cells are the most responsive to chemopreventive agents, and may be the cell line of choice for screening melanoma prevention agents.
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ABSTRACT: Based on large cardiovascular clinical trials of lipid lowering agents that showed a considerable decrease in incidence of primary melanomas in the active agent arm, we have carried out a randomized, double-blind clinical trial examining the impact of lovastatin on various biomarkers of melanoma pathogenesis. Subjects with at least two clinically atypical nevi, were randomized to receive oral lovastatin or placebo for a six month period. Clinical, histopathologic, and molecular biomarkers were evaluated for change in the two groups. 80 subjects were randomized, evaluable, and included in the analyses. Lovastatin showed no benefit in comparison to placebo in the primary endpoint of decreasing the level of histopathologic atypia, nor in any of the secondary endpoints of decreasing clinical atypia, impact on nevus number, nor in showing significant changes in any of the molecular biomarkers. There were no significant differences in adverse event profiles for lovastatin compared to placebo. The lovastatin arm did show a significant and considerable decrease in total serum cholesterol and serum LDL levels compared to placebo, an expected result. This finding bolsters confidence in subject compliance. Given the results of this trial, it is concluded that if lovastatin were to lower the incidence of melanoma, it would appear not to be doing so by reversing atypia of precursor atypical nevi over the six month time frame studied. Further research into the pathogenesis of melanoma and in other potential chemopreventive agents is needed. NCT00462280 FUNDING: NCI NO-1 CN-35160.Cancer Prevention Research 03/2014; · 4.89 Impact Factor
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ABSTRACT: The BRAFV600E mutation is common in human melanoma. This mutation enhances IkappaB kinase (IKK)/nuclear factor-kappaB (NF-kappaB) and extracellular signal-regulated kinase/activator protein signaling cascades. In this study, we evaluated the efficacy of targeting either B-Raf or IKKbeta in combination with the DNA alkylating agent temozolomide for treatment of advanced metastatic melanoma. Xenografts of Hs294T human metastatic melanoma cells exhibiting the BRAFV600E mutation were treated with inhibitors of IKKbeta (BMS-345541), B-Raf (BAY 54-9085), and/or temozolomide. Drug response was mechanistically analyzed in vitro and in vivo. In this study, we determined that the antitumor activity of all three drugs depends on inhibition of NF-kappaB. BMS-345541 inhibits IKKbeta-mediated phosphorylation of IkappaBalpha and thus blocks the nuclear localization of NF-kappaB, whereas BAY 54-9085 inhibits activation of NF-kappaB through a mechanism that does not involve stabilization of IkappaBalpha. Moreover, BMS-345541, but not BAY 54-9085, activates the death pathways of p53 and c-Jun-NH2-kinase, contributing to the killing of melanoma cells. Temozolomide inhibits both NF-kappaB and extracellular signal-regulated kinase activity, conferring effective in vivo antitumor activity. Thus, temozolomide, but not BAY 54-9085, has a synergistic in vivo antitumor effect with BMS-345541. We conclude that the efficacy of antimelanoma therapy depends on inhibition of expression of antiapoptotic genes transcriptionally regulated by NF-kappaB. In contrast, drug targeting of the extracellular signal-regulated kinase/mitogen-activated protein kinase pathway alone in melanoma cells is ineffective for melanoma therapy in cases where NF-kappaB is not also targeted.Molecular Cancer Therapeutics 04/2009; 8(3):636-47. · 6.11 Impact Factor
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ABSTRACT: Dietary factors influence carcinogenesis in a variety of tissues. The consumption of fruits and vegetables is associated with a decreased risk of several types of epithelial malignancies. In addition, there are interrelationships between diet, environmental factors, and genetics that can affect cancer risk. Potential chemopreventive agents against cancer development can be found among nutritive and/or nonnutritive compounds in inedible and edible plants. To identify potential cancer chemopreventive agents, scientists are evaluating hundreds of phytochemicals for the prevention of cancer. This short review article describes in vitro and in vivo assays reported to identify potential cancer preventive compounds from plants.Scholarly Research Exchange 01/2009; 2009.