Abstract 2544: Combination of anti-cancer small molecule tolfenamic acid and curcumin effectively inhibits colon cancer cell growth

Abstract

Abstract Tolfenamic acid (TA) is small molecule and non-steroidal anti-inflammatory drug which is known to inhibit human cancer cells and mouse tumor growth in some cancer models. TA is known to target the transcription factor, specificity protein1 (Sp1), that mediates the expression of several genes associated with cancer, including survivin, a key member of the inhibitor of apoptosis proteins (IAP) family. Curcumin is an aromatic constituent of the plant curcuma longa (turmeric) which is extensively studied in some malignancies including breast, pancreatic and colon cancers. Even though curcumin shows a broad spectrum of anti-cancer activity in pre-clinical studies, its clinical application is greatly affected by its low bioavailability. Hence, several strategies to improve the therapeutic response of curcumin are being pursued, including the synthesis of curcumin analogs and using curcumin in combination with other small molecules or drugs to increase bioavailability. In this study, using a colon cancer model, the therapeutic efficacy of curcumin and a curcumin analog EF31 in combination with an anti-cancer small molecule TA was evaluated. Colon cancer cell lines HCT116, HT29, and SW620 were treated with TA, curcumin, or EF31 and cell viability was measured at 24, 48, and 72 hours post-treatment. All agents showed a steady and consistent decrease in cell viability, following a clear dose and time-dependent response. Combination of TA with curcumin or EF31 showed higher growth inhibition compared to single agent treatment. Analysis of apoptosis was carried out to determine the mode of growth inhibition, using flow cytometry (JC-1 staining) Western blot analysis (poly-ADP ribose polymerase [PARP] cleavage), and caspase3/7 activity. Results demonstrated a significant increase in the apoptotic fraction (JC-1 staining) following combination treatment, when compared to individual effect. This was accompanied by the activation of caspases (caspase 3/7) and the PARP cleavage. Western blot results also revealed that combination treatment of TA with curcumin or EF31 significantly decreased expression of Sp1, Nuclear Factor-kappa light chain enhancer of B cells (NF-kB), and survivin, and modulated the expression of proteins associated with the cell cycle. These pre-clinical results demonstrate that the anti-cancer small molecule, tolfenamic acid, may enhance the therapeutic efficacy of curcumin or curcumin analogs in colon cancer. Mechanistic studies to delineate the pathways involved in combination treatment are under investigation. Citation Format: Umesh T. Sankpal, Ganji Purnachandra Nagaraju, Myrna Hurtado, Sriharika R. Gottipolu, Bassel El-Rayes, Mamoru Shoji, Christopher G. Jordan, Riyaz Basha. Combination of anti-cancer small molecule tolfenamic acid and curcumin effectively inhibits colon cancer cell growth. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 2544. doi:10.1158/1538-7445.AM2015-2544