title: Synergy between enzastaurin doxorubicin in inducing melanoma apoptosis.
abstract: Melanoma is resistant to most standard chemotherapeutics. We analysed the combined effect of doxorubicin and enzastaurin on cell death of four melanoma cell lines, namely G361, SK-MEL3, A375 and SAN. Enzastaurin IC50 was calculated by measure of growth inhibition with MTS assay and corresponded to 2 μM; the half maximal cytotoxicity of doxorubicin was obtained at 3 μM dose. Evaluation of combination index showed synergism (CI > 1) or additive effect (CI = 1) with all melanoma cell lines, with enzastaurin doses ≥0.6 μM and doxorubicin doses ≥1 μM. Combination of the two drugs resulted in increase in caspase 3 and 8 activation, in comparison with activation by single agents. Caspase 8 activation was impaired by TNFR-1 blocking. Our results show doxorubicin-stimulated production of TNFα, whereas enzastaurin-stimulated TNFR-1 expression on plasma membrane. The effect on TNFR-1 appeared to be mediated by PKCζ inhibition. Taken together, our findings suggest that enzastaurin increases doxorubicin-induced apoptosis of melanoma by a mechanism involving, at least in part, activation of the TNF-α signal.
authors.affiliation: Dipartimento di Medicina Molecolare e Biotecnologie Mediche, Federico II University, Napoli, Italy.
authors.forename: Simona
authors.initials: S
authors.lastname: Romano
authors.forename: Giovanna
authors.initials: G
authors.lastname: Nappo
authors.forename: Gaetano
authors.initials: G
authors.lastname: Calì
authors.forename: Samuel Y-S
authors.initials: SY
authors.lastname: Wang
authors.forename: Stefania
authors.initials: S
authors.lastname: Staibano
authors.forename: Anna
authors.initials: A
authors.lastname: D'Angelillo
authors.forename: Gennaro
authors.initials: G
authors.lastname: Ilardi
authors.forename: Antonio
authors.initials: A
authors.lastname: Sorrentino
authors.forename: Anna Laura
authors.initials: AL
authors.lastname: Di Pace
authors.forename: Maria
authors.initials: M
authors.lastname: Siano
authors.forename: Rita
authors.initials: R
authors.lastname: Bisogni
authors.forename: Maria Fiammetta
authors.initials: MF
authors.lastname: Romano
mesh_terms: D017209:Apoptosis / Q000187:drug effects*; D045744:Cell Line, Tumor; D004317:Doxorubicin / Q000494:pharmacology* / Q000627:therapeutic use; D004357:Drug Synergism; D020868:Gene Silencing / Q000187:drug effects; D006801:Humans; D007211:Indoles / Q000494:pharmacology* / Q000627:therapeutic use; D008545:Melanoma / Q000188:drug therapy / Q000201:enzymology / Q000473:pathology*; D010766:Phosphorylation / Q000187:drug effects; D011493:Protein Kinase C / Q000378:metabolism; D047888:Receptors, Tumor Necrosis Factor, Type I / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects; D013379:Substrate Specificity / Q000187:drug effects; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism; D000099221:Protein Kinase C zeta
chemical_list: D004317:Doxorubicin; D007211:Indoles; D011493:Protein Kinase C; D047888:Receptors, Tumor Necrosis Factor, Type I; D014409:Tumor Necrosis Factor-alpha; D000099221:Protein Kinase C zeta; C504878:enzastaurin
keywords: TNF-α; apoptosis; chemotherapy; melanoma