Abstract 5500: Ormeloxifene modulates beta-catenin/TCF pathway in colon cancer.

Abstract

Abstract BACKGROUND: Colorectal cancer is the leading cause of cancer-related death and the third most commonly diagnosed cancer in both males and females in the US. While the overall rates of colon cancer have been steadily falling in the past decade, the rates of colon cancer continue to increase in the under-50 age group. Therefore, developing newer strategies for the prevention and treatment of colon cancer is urgently needed. Aberrant β-catenin signaling has been detected in over 90% of colon cancer and is a central signaling pathway leading to the development of colon cancer. Mutations in components of this pathway lead to the accumulation of β-catenin in the nucleus where it functions as a co-transcription factor to transcribe proto-oncogenes. Therefore, strategies to regulate this specific signaling pathway can be developed as a novel therapeutic modality for the treatment of colon cancer. Ormeloxifene is a synthetic non-steroidal selective estrogen receptor modulator that has been widely used as an oral contraceptive and has demonstrated promising results in the inhibition of breast cancer. Herein, we have investigated the effect of ormeloxifene on colon cancer cell growth and its effect on β-catenin transcriptional activity. MATERIALS AND METHODS: SW480, SW620 colon cancer cells were used to investigate the effect of ormeloxifene (5-20 μM) on various cellular characteristics, including cell proliferation, clonogenic potential, motility and aggregation using standard procedures. β-catenin/T cell factor (TCF) transcription activity was measured by luciferase reporter assays using reporter constructs Topflash or Fopflash and pRL-TK (Renilla luciferase) and with Dual-Glo reagent. The expression and subcellular localization of proteins was determined by immunoblotting and confocal microscopy. RESULTS: Ormeloxifene demonstrated a concentration dependent (5-20 μM) inhibition of cell proliferation in the colon cells. In addition, ormeloxifene very effectively suppressed growth of colon cancer cells in both anchorage dependent and anchorage independent colony formation assays. Furthermore, ormeloxifene effectively inhibited cellular motility of colon cancer cells. Repression of these cellular phenotypes was correlated with attenuation of β-catenin/TCF4 transcriptional activity and the modulation of subcellular localization of β-catenin. Western blot analyses revealed reduction of TCF4 levels upon ormeloxifene treatment. CONCLUSION: Our findings suggest that ormeloxifene effectively inhibits tumorigenic characteristics of colon cancer cells via attenuating the β-catenin/TCF4 signaling pathway. It may therefore be a novel therapeutic modality for the prevention, treatment and management of colon cancer. Citation Format: Vasudha Sundram, Rishi Kumar Gara, Man Mohan Singh, Subhash C. Chauhan, Meena Jaggi. Ormeloxifene modulates beta-catenin/TCF pathway in colon cancer. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 5500. doi:10.1158/1538-7445.AM2013-5500