Interleukin 6 (IL-6) is a pro-inflammatory cytokine that plays an important role in the progression of many types of cancers by regulating macrophage recruitment and differentiation, as well as modulating the activation of the JAK/Stat signal cascade, and inducing pro-angiogenic factors. Several studies have correlated a negative prognosis in cancer with a high level of IL-6 in patient serum. Triple (i.e. progesterone, human epidermal growth factor-2, and estrogen receptor) negative breast cancer has been reported to be highly aggressive and invasive. MDA-MB-231, a triple negative breast cancer cell line, expresses high basal levels of IL-6. Recently our laboratory demonstrated that phenylmethimazole (C10), a novel toll-like receptor inhibitor, diminishes basal expression of IL-6 in pancreatic cancer and melanoma cells as well as their growth and migration. Based on these observations, we sought to test the hypothesis that C10 inhibits IL-6 expression in MDA-MB-231 cells. Here we report that triple negative breast cancer cells express considerably higher levels of IL-6 than estrogen receptor positive breast cancer cells and that C10 significantly reduces IL-6 expression in the triple negative breast cancer cells. This inhibition was observed at both the RNA and protein level. Given the importance of IL-6 in cancer progression, and our finding that C10 attenuates IL-6 expression in the MDA-MB-231 cell line, this study suggests that C10 may have therapeutic potential for triple negative breast cancers. Additional studies are currently underway to further explore these hypotheses.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 1932. doi:1538-7445.AM2012-1932