PURPOSE: Recent insights regarding the pathogenesis of malignant pleural mesothelioma (MPM) provide new opportunities for targeted molecular therapies for this highly lethal disease. The present study was undertaken to examine the effects of the histone deacetylase inhibitor, Depsipeptide (DP) FK228, in conjunction with the cyclin-dependent kinase inhibitor, Flavopiridol (FLA), in cultured MPM cells. EXPERIMENTAL DESIGN: Proliferation and apoptosis in drug-treated, virally transduced, or control cells were assessed by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide and Apo-bromodeoxyuridine techniques. Western blot and ELISA techniques were used to examine signal transduction and cell cycle-related protein levels in MPM cells exposed to DP and/or FLA in the presence or absence of calphostin, phorbol-12,13-dibutyrate, 5,6-dichloro-1-beta-D-ribofuranosyl-benzimidazole, or adenoviral p21 transduction. RESULTS: DP (1-50 ng/ml x 6 h) or FLA (100-200 nM x 72 h) alone, mediated low-level, dose-dependent growth inhibition in MPM cells. In contrast, sequential DP/FLA treatment mediated marked growth inhibition and apoptosis in these cell lines. The cytotoxic effects of DP/FLA were considerably less pronounced in cultured normal cells. The proapoptotic effects of DP/FLA treatment coincided with inhibition of DP-mediated induction of p21 by FLA. Overexpression of p21 by adenoviral gene transfer techniques rendered MPM cells refractory to the cytotoxic effects of this treatment regimen. In p21 reporter assays, promoter activation by DP was antagonized by FLA. The magnitude of inhibition of DP-mediated p21 induction by FLA exceeded that observed with the pTEFb antagonist 5,6-dichloro-1-beta-D-ribofuranosyl-benzimidazole. Calphostin C abrogated p21 induction mediated by DP and enhanced DP-mediated apoptosis in a manner comparable with FLA in MPM cells; in contrast, phorbol-12,13-dibutyrate blocked FLA-mediated inhibition of p21 induction by DP and markedly protected these cells from the apoptotic effects of sequential DP/FLA. CONCLUSIONS: FLA abrogates DP-mediated induction of p21 expression, in part, via inhibition of protein kinase C signaling and markedly potentiates the cytotoxic effects of DP in MPM cells.
PURPOSE: Recent insights regarding the pathogenesis of malignant pleural mesothelioma (MPM) provide new opportunities for targeted molecular therapies for this highly lethal disease. The present study was undertaken to examine the effects of the histone deacetylase inhibitor, Depsipeptide (DP) FK228, in conjunction with the cyclin-dependent kinase inhibitor, Flavopiridol (FLA), in cultured MPM cells. EXPERIMENTAL DESIGN: Proliferation and apoptosis in drug-treated, virally transduced, or control cells were assessed by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide and Apo-bromodeoxyuridine techniques. Western blot and ELISA techniques were used to examine signal transduction and cell cycle-related protein levels in MPM cells exposed to DP and/or FLA in the presence or absence of calphostin, phorbol-12,13-dibutyrate, 5,6-dichloro-1-beta-D-ribofuranosyl-benzimidazole, or adenoviral p21 transduction. RESULTS:DP (1-50 ng/ml x 6 h) or FLA (100-200 nM x 72 h) alone, mediated low-level, dose-dependent growth inhibition in MPM cells. In contrast, sequential DP/FLA treatment mediated marked growth inhibition and apoptosis in these cell lines. The cytotoxic effects of DP/FLA were considerably less pronounced in cultured normal cells. The proapoptotic effects of DP/FLA treatment coincided with inhibition of DP-mediated induction of p21 by FLA. Overexpression of p21 by adenoviral gene transfer techniques rendered MPM cells refractory to the cytotoxic effects of this treatment regimen. In p21 reporter assays, promoter activation by DP was antagonized by FLA. The magnitude of inhibition of DP-mediated p21 induction by FLA exceeded that observed with the pTEFb antagonist 5,6-dichloro-1-beta-D-ribofuranosyl-benzimidazole. Calphostin C abrogated p21 induction mediated by DP and enhanced DP-mediated apoptosis in a manner comparable with FLA in MPM cells; in contrast, phorbol-12,13-dibutyrate blocked FLA-mediated inhibition of p21 induction by DP and markedly protected these cells from the apoptotic effects of sequential DP/FLA. CONCLUSIONS:FLA abrogates DP-mediated induction of p21 expression, in part, via inhibition of protein kinase C signaling and markedly potentiates the cytotoxic effects of DP in MPM cells.
Authors: Susan E Bates; Zhirong Zhan; Kenneth Steadman; Tomasz Obrzut; Victoria Luchenko; Robin Frye; Robert W Robey; Maria Turner; Erin R Gardner; William D Figg; Seth M Steinberg; Alex Ling; Tito Fojo; Kin Wah To; Richard L Piekarz Journal: Br J Haematol Date: 2009-10-28 Impact factor: 6.998
Authors: Mahadev Rao; Scott M Atay; Vivek Shukla; Young Hong; Trevor Upham; R Taylor Ripley; Julie A Hong; Mary Zhang; Emily Reardon; Patricia Fetsch; Markku Miettinen; Xinmin Li; Cody J Peer; Tristan Sissung; William D Figg; Assunta De Rienzo; Raphael Bueno; David S Schrump Journal: Clin Cancer Res Date: 2015-10-12 Impact factor: 12.531
Authors: Beata Holkova; Jeffrey G Supko; Matthew M Ames; Joel M Reid; Geoffrey I Shapiro; Edward Brent Perkins; Viswanathan Ramakrishnan; Mary Beth Tombes; Connie Honeycutt; Renee M McGovern; Maciej Kmieciak; Ellen Shrader; Martha D Wellons; Heidi Sankala; Austin Doyle; John Wright; John D Roberts; Steven Grant Journal: Clin Cancer Res Date: 2013-03-20 Impact factor: 12.531