Xanthohumol inhibits the neuroendocrine transcription factor achaete-scute complex-like 1, suppresses proliferation, and induces phosphorylated ERK1/2 in medullary thyroid cancer

BACKGROUND: Achaete-scute complex-like 1 (ASCL1) is a transcription factor important in the malignant development of medullary thyroid cancer (MTC). Activation of Raf-1 signaling is associated with ASCL1 suppression and growth inhibition. Xanthohumol, a natural compound, has recently been shown to have anticancer properties. We thus hypothesized that xanthohumol would suppress growth by activating Raf-1 signaling, thus altering the malignant phenotype of MTC. METHODS: Human MTC cells were treated with xanthohumol (0-30 mu mol/L) for up to 6 days. Proliferation was measured by a methylthiazolyldiphenyl-tetrazolium bromide (MTT) colorimetric assay. Western blot analysis was performed for ASCL1 and markers of Raf-1 pathway activation. RESULTS: Treatment of MTC cells with xanthohumol resulted in a close dependent inhibition of growth. Additionally, induction of phosphorylated ERK1/2 and a reduction of ASCL1 protein was noted. CONCLUSIONS: Xanthohumol is a potent Raf-1 activator in MTC cells. This compound suppresses MTC growth, alters the malignant phenotype, and warrants further preclinical study. (C) 2010 Elsevier Inc. All rights reserved.