Antitumor activity of CTFB, a novel anticancer agent, is associated with the down-regulation of nuclear factor-κB expression and proteasome activation in head and neck squamous carcinoma cell lines

Abstract

This study aimed to characterize the antitumor activity of 5-Chloro-N-{2-[2-(4-chloro-phenyl)-3-methyl-butoxy]-5-trifluoromethyl-phenyl}-2-hydroxy-benzamide (CTFB), a novel anticancer agent, in head and neck cancer cell lines, FaDu, SCC-25 and cisplatin-resistant CAL-27. CTFB was generated as a result of an extensive medicinal chemistry effort on a lead compound series discovered in a high-throughput screen for inducers of apoptosis. All cell lines showed significant growth delay in response to CTFB treatment at a concentration of 1 Mmol/L with 17.16 F 2.08%, 10.92 F 1.22%, and 27.03 F 1.86% of cells surviving at 120 h in FaDu, CAL-27, and SCC-25, respectively. To define proteins involved in the mechanism of action of CTFB, we determined differences in the proteome profile of cell lines before and after treatment with CTFB using two-dimensional difference gel electrophoresis followed by computational image analysis and mass spectrometry. Eight proteins were found to be regulated by CTFB in all cell lines. All these proteins are involved in cytoskeleton formation and function and/or in cell cycle regulation. We showed that CTFB-induced cell growth delay was accompanied by cell cycle arrest at the G 0 -G 1 phase that was associated with the up-regulation of p21/ WAF1 and p27/Kip1 expression and the down-regulation of cyclin D1. Furthermore, we showed that activity of CTFB depended on the down-regulation of nuclear factor-KB (NF-KB) and NF-KB p65 phosphorylated at Ser 536 . The level of proteasome activity correlated with the response to CTFB treatment, and the down-regulation of NF-KB is accompanied by enhanced proteasome activity in all investigated head and neck cancer cell lines. In this report, we show that CTFB reveals multiple effects that lead to delayed cell growth. Our data suggest that this compound should be studied further in the treatment of head and neck cancer. [Mol Cancer Ther 2007;6(6):1898 -908]

NFκB mediates cisplatin resistance through histone modifications in head and neck squamous cell carcinoma (HNSCC)

“…2A_Ac.H3) [25,26]. Histone deacetylation is involved in enhanced histone–DNA interactions and chromatin condensation [27–29]. Interestingly, cisplatin had no effect on histone H3 levels in chemosensitive and control cells, as evidenced by the similarities to vehicle control.…”

“…We next wanted to determine whether NFκB plays a role in chromatin condensation given that NFκB was activated (nuclear accumulation) in chemoresistant HN13 cells and inactivated (cytoplasmic accumulation) in HN6 cells (chemosensitive). Numerous signaling proteins can activate NFκB, including TNF‐α, which triggers rapid degradation of IκBα that is mediated by TNFR1 and results in nuclear accumulation of NFκB [27,40] (Supplementary Fig. S3).…”

Rac1 as a potential therapeutic target for chemo-radioresistant head and neck squamous cell carcinomas (HNSCC)

“…Subcellular fractionation to obtain nuclear and cytoplasmic fractions was performed as previously described (Skvortsov et al , 2007). Briefly, 4 × 10 7 cells were lysed in the cytoplasmic extract buffer and then centrifuged at 200  g .…”

Intracellular signaling pathways regulating radioresistance of human prostate carcinoma cells

“…In order to enrich low abundant proteins and signaling complexes, subcellular fractionation was performed [17]. 2-D DIGE was performed as published previously [18]. Briefly, for sample preparation, cells were scraped and harvested by centrifuging at 47C for 5 min at 1006g.…”