Characterization and mechanistic studies of a novel melanoma-targeting construct containing IκBa for specific inhibition of nuclear factor-κB activity.

Hong Zhou, Yuying Liu, Lawrence H. Cheung, Sehoon Kim, Weihe Zhang, Khalid A. Mohamedali, Preetha Anand, Walter N. Hittelman, Bharat B. Aggarwal, Michael G. Rosenblum

Research output: Contribution to journalArticle

Abstract

The transcription factor nuclear factor-κB (NF-κB) is a central mediator of growth and homeostasis for both normal and neoplastic cells. IκBα is the natural intracellular inhibitor of NF-κB and can effectively complex with and thereby inhibit the biologic activity and translocation of NF-κB to the nucleus. We designed a fusion protein designated IκBα/scFvMEL composing of human IκBα and the single-chain antibody scFvMEL, targets melanoma gp240 antigen. Cells treated with IκBα/scFvMEL before irradiation showed specifically inhibition of both constitutive and radiation-induced NF-κB activity on gp240 antigen-positive A375M cells. Pretreatment of A375M cells with IκBα/scFvMEL significantly sensitized melanoma cells to ionizing radiation assessed using a clonogenic survival assay. Mechanistic studies showed that IκBα/scFvMEL, when exogenously added to A375M cells, could be coimmunoprecipitated with the p65 subunit of NF-κB. IκBα/scFvMEL inhibited in a time and/or dose-dependent manner of tumor necrosis factor α- or radiation-induced NF-κB activity in vitro. IκBα/scFvMEL was also shown to specifically inhibit the translocation of the NF-κB p65 subunit to the cell nucleus and NF-κB-mediated gene transcription. Further, initial studies showed that mice bearing well-established A375M xenografts were treated (intravenously) with IκBα/scFvMEL and showed a significant suppression of tumor growth. We also observed a decrease in levels of Bcl-2 and Bcl-XL signaling events downstream of NF-κB in the tumor model. These studies demonstrate for the first time that tumor cell-targeted delivery of IκBα may be beneficial for the treatment of melanoma when combined with standard anticancer therapies such as radiation.

Original languageEnglish (US)
Pages (from-to)766-777
Number of pages12
JournalNeoplasia (New York, N.Y.)
Volume12
Issue number10
StatePublished - Jan 1 2010

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    Zhou, H., Liu, Y., Cheung, L. H., Kim, S., Zhang, W., Mohamedali, K. A., Anand, P., Hittelman, W. N., Aggarwal, B. B., & Rosenblum, M. G. (2010). Characterization and mechanistic studies of a novel melanoma-targeting construct containing IκBa for specific inhibition of nuclear factor-κB activity. Neoplasia (New York, N.Y.), 12(10), 766-777.