Potential Use of Cetrimonium Bromide as an Apoptosis-Promoting Anticancer Agent for Head and Neck Cancer

Abstract

A potential therapeutic agent for human head and neck cancer (HNC), cetrimonium bromide (CTAB), was identified through a cell-based phenotype-driven high-throughput screen (HTS) of 2000 biologically active or clinically used compounds, followed by in vitro and in vivo characterization of its antitumor efficacy. The preliminary and secondary screens were performed on FaDu (hypopharyngeal squamous cancer) and GM05757 (primary normal fibroblasts), respectively. Potential hit compounds were further evaluated for their anticancer specificity and efficacy in combination with standard therapeutics on a panel of normal and cancer cell lines. Mechanism of action, in vivo antitumor efficacy, and potential lead compound optimizations were also investigated. In vitro, CTAB interacted additively with ␥ radiation and cisplatin, two standard HNC therapeutic agents.CTAB exhibited anticancer cytotoxicity against several HNC cell lines, with minimal effects on normal fibroblasts; a selectivity that exploits cancer-specific metabolic aberrations. The central mode of cytotoxicity was mitochondria-mediated apoptosis via inhibition of H ϩ -ATP synthase activity and mitochondrial membrane potential depolarization, which in turn was associated with reduced intracellular ATP levels, caspase activation, elevated sub-G 1 cell population, and chromatin condensation. In vivo, CTAB ablated tumor-forming capacity of FaDu cells and delayed growth of established tumors. Thus, using an HTS approach, CTAB was identified as a potential apoptogenic quaternary ammonium compound possessing in vitro and in vivo efficacy against HNC models.

Efficacy of Combining GMX1777 with Radiation Therapy for Human Head and Neck Carcinoma

“…After 24 h following seeding in six-well plates (3 × 10 5 per well), FaDu cells were treated with GMX1778 (10 nmol/L) ± radiation (4 Gy) 24 h later. Two days after radiation, cells were processed for cell cycle analysis as described previously (18). For determination of propidium iodide (PI) positivity, FaDu cells were harvested and washed with fluorescence-activated cell sorting buffer (0.5% bovine serum albumin-PBS) after treatment,…”

“…GM05757, a primary normal human fibroblast strain, was obtained from the Coriell Institute for Medical Research. C666-1 and FaDu cells were cultured as described previously (17,18). All cell lines were authenticated via microscopic morphology check and growth curve analysis.…”

“…Colony formation assays for FaDu cells were conducted as described previously (18). GMX1778 or vehicle control was added at the specified concentrations.…”

“…FaDu and C666-1 cells were seeded (0.5 × 10 6 per T-25 flask), allowed to incubate for 1 day, and treated with 10 nmol/L GMX1778. After 24 h for FaDu and 48 h for C666-1, cells were stained with Hoechst 33342 (Invitrogen) and visualized by fluorescence microscopy as described previously (18).…”

Cellular Uptake, Intracellular Trafficking and Biological Responses of Gold Nanoparticles

“…The CTAB molecules alone can penetrate into cells, target at and damage mitochondria, and finally induce apoptosis. 33 Furthermore, GNRs with different coatings, like CTAB, PSS and PDDAC molecules, were used to study the origin of toxicity. The other two types of GNRs exhibit less cytotoxicity than CTAB-coated ones (Fig.…”