title: Efficacy of different sequences of radio- and chemotherapy in experimental models of human melanoma.
abstract: Although combination chemotherapy and radiotherapy have become the standard of care in numerous tumors, the mechanisms of interaction are often still unclear. The purpose of this study was to analyze the efficacy of radiation treatment and cisplatin sequences and to investigate their mechanisms of interaction. Three melanoma cell lines were used to evaluate in vitro radiation-induced cytotoxicity before and after cisplatin treatment. Expression levels of a panel of genes were determined by real-time RT-PCR. Cytotoxic effect was evaluated by flow cytometry analysis and Comet assay. We also used normal human dermal fibroblasts (HUDE) to evaluate the cytotoxicity of the two treatments by clonogenic assay. Radiation and cisplatin used singly were not particularly effective in reducing proliferation in melanoma cells. Conversely, radiation treatment followed by cisplatin showed a strong synergistic interaction in all cell lines, with a ratio index ranging from 16 to >100. The synergistic effect was accompanied by apoptosis induction (up to 40%) and an increase in the percentage of comet-shaped nucleoids from 85% to 99%. In parallel, our results also showed that radiation treatment of HUDE fibroblasts followed by cisplatin only induced weak cytotoxicity. Our findings highlight the efficacy of the sequence radiation → cisplatin in reducing cell proliferation and in inducing apoptosis in melanoma cell lines. This sequence also modulated a network of proteins involved in DNA damage repair.
authors.affiliation: Biosciences Laboratory, Istituto Scientifico Romagnolo per lo Studio e la Cura dei Tumori (IRST) IRCCS, Meldola, Italy.
authors.forename: Chiara
authors.initials: C
authors.lastname: Arienti
authors.forename: Wainer
authors.initials: W
authors.lastname: Zoli
authors.forename: Sara
authors.initials: S
authors.lastname: Pignatta
authors.forename: Silvia
authors.initials: S
authors.lastname: Carloni
authors.forename: Giulia
authors.initials: G
authors.lastname: Paganelli
authors.forename: Paola
authors.initials: P
authors.lastname: Ulivi
authors.forename: Antonino
authors.initials: A
authors.lastname: Romeo
authors.forename: Enrico
authors.initials: E
authors.lastname: Menghi
authors.forename: Anna
authors.initials: A
authors.lastname: Sarnelli
authors.forename: Laura
authors.initials: L
authors.lastname: Medri
authors.forename: Rolando
authors.initials: R
authors.lastname: Polico
authors.forename: Rosella
authors.initials: R
authors.lastname: Silvestrini
authors.forename: Anna
authors.initials: A
authors.lastname: Tesei
mesh_terms: D000970:Antineoplastic Agents / Q000494:pharmacology* / Q000633:toxicity; D017209:Apoptosis / Q000187:drug effects / Q000528:radiation effects; D002453:Cell Cycle / Q000187:drug effects / Q000528:radiation effects; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects / Q000528:radiation effects; D002470:Cell Survival / Q000187:drug effects / Q000528:radiation effects; D059248:Chemoradiotherapy / Q000009:adverse effects / Q000379:methods*; D002945:Cisplatin / Q000494:pharmacology* / Q000633:toxicity; D020552:Comet Assay; D004249:DNA Damage; D004305:Dose-Response Relationship, Drug; D004307:Dose-Response Relationship, Radiation; D004334:Drug Administration Schedule; D005434:Flow Cytometry; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects / Q000528:radiation effects; D006801:Humans; D020128:Inhibitory Concentration 50; D008545:Melanoma / Q000235:genetics / Q000473:pathology*; D060888:Real-Time Polymerase Chain Reaction; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012878:Skin Neoplasms / Q000235:genetics / Q000473:pathology*; D013997:Time Factors
chemical_list: D000970:Antineoplastic Agents; D002945:Cisplatin