Bortezomib pre-treatment prolongs interferon-alpha-induced STAT1 phosphorylation in melanoma cells
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Bortezomib is a proteasome inhibitor that can synergize with interferon-alpha (IFN-α) to induce apoptosis in melanoma cells in vitro and inhibit tumor growth in vivo. We hypothesized that proteasome inhibition may be an effective means to sensitize melanoma cells to the direct effects of IFN-α. Pre-treatment of human melanoma cells with bortezomib led to significantly increased transcription of interferon-stimulated genes as determined by real-time PCR. Flow cytometric and immunoblot analyses indicated that the enhanced direct actions of IFN-α on melanoma cells were the result of prolonged phosphorylation of STAT1 (P-STAT1) on both the Tyrosine701 and Serine727 residues. In contrast, the enhanced IFN-α-induced P-STAT1 was not observed in peripheral blood mononuclear cells that were pre-treated with bortezomib. These data suggest that proteasome inhibition represents a mechanism to enhance the direct effects of IFN-α on melanoma cells thereby complementing its immunostimulatory properties.
KeywordsBortezomib Proteasome inhibition Interferon STAT1 Melanoma
- 1.American Cancer Society (2007) Cancer facts and figures for 2006. American Cancer Society, AtlantaGoogle Scholar
- 6.Moschos SJ, Edington HD, Land SR et al (2006) Neoadjuvant treatment of regional stage IIIB melanoma with high-dose interferon alfa-2b induces objective tumor regression in association with modulation of tumor infiltrating host cellular immune responses. J Clin Oncol 24(19):3164–3171PubMedCrossRefGoogle Scholar