title: Adenovirus-mediated FKHRL1/TM sensitizes melanoma cells to apoptosis induced by temozolomide.
abstract: Melanoma exhibits variable resistance to the alkylating agent temozolomide (TMZ). We evaluated the potential of adenovirus expressing forkhead human transcription factor like 1 triple mutant (Ad-FKHRL1/TM) to sensitize melanoma cells to TMZ. Four melanoma cell lines were treated with Ad-FKHRL1/TM and TMZ, alone or in combination. Apoptosis was assessed by activation and inhibition of caspase pathway, nuclei fragmentation, and annexin V staining. The potential therapeutic efficacy of Ad-FKHRL1/TM with TMZ was also assessed in a mouse melanoma xenograft model. Combination therapy of Ad-FKHRL1/TM and TMZ resulted in greater cell killing (<20% cell viability) compared to single therapy and controls (p<0.05). Combination indices of Ad-FKHRL1/TM and TMZ therapy indicated significant (p<0.05) synergistic killing effect. Greater apoptosis induction was found in cells treated with Ad-FKHRL1/TM and TMZ than Ad-FKHRL1/TM or TMZ-treated cells alone. Treatment with temozolomide enhanced adenovirus transgene expression in a cell type-dependent manner. In an in vivo model, combination therapy of Ad-FKHRL1/TM with TMZ results in greater tumor growth reduction in comparison with single treatments. We suggest that Ad-FKHRL1/TM is a promising vector to sensitize melanoma cells to TMZ, and that a combination of both approaches would be effective in the clinical setting.
authors.affiliation: University of Louisville, Surgery, Louisville, Kentucky, United States ; michael.egger@louisville.edu.
authors.forename: Michael
authors.initials: M
authors.lastname: Egger
authors.forename: Lacey
authors.initials: L
authors.lastname: McNally
authors.forename: Jonathan
authors.initials: J
authors.lastname: Nitz
authors.forename: Kelly M
authors.initials: KM
authors.lastname: McMasters
authors.forename: Jorge G
authors.initials: JG
authors.lastname: Gomez-Gutierrez