Abstract 4116: Grape seed extract impairs adipocyte-colorectal cancer cell interaction and decreases adipocyte-driven colon cancer stem colonosphere formation

Proceedings: AACR Annual Meeting 2014; April 5-9, 2014; San Diego, CA Colorectal cancer (CRC) is the 3rd leading malignancy with additional increased risks due to obesity, type II diabetes and/or inflammatory bowel disease. Whereas chemopreventive potential of a wide-range of agents against CRC has been studied, the major limitation of most of these studies is a lack of investigation of agent efficacy under obese conditions, which is associated with increased CRC risk, incidence and mortality. Given the global obesity epidemic, it is thus imperative that we discover and develop agents with efficacy against CRC under obese conditions. The role of adipocytes, which are the major players in obesity, on colon carcinogenesis is just beginning to unfold. Since colon lies in close anatomical vicinity of fat depots, it is now acknowledged that there is a bi-directional cross-talk between both cell types, leading to dramatic phenotypic /functional modifications in both adipocytes and CRC cells. Thus we hypothesize that an agent, such as grape seed extract (GSE), with both anti-obesogenic and anti-CRC activities, would be ideal to impair different facets of adipocyte-CRC interaction resulting in CRC chemoprevention under obese conditions. Indeed, we found that GSE pre-treatment of adipocytes (in co-culture under direct cell to cell or no contact models using a 3D matrigel culture system) decreases their growth promoting effects on CRC cells. In addition, adipocyte-conditioned media, collected after chronic and acute pre-treatment with GSE, significantly decreased the chemotactic properties of adipocytes towards CRC cell invasion. Next, we determined GSE effect on the self renewal capacity of the cancer stem cells (CSC) population by first isolating CD44+EpCAMhigh cells from the CRC cell lines, SW480, HT-29 and LoVo, and then subjecting them to sphere cluster formation assays. GSE significantly decreased: colonosphere formation by colon CSC, mRNA levels of various CSC regulatory molecules, and CSC-associated markers and transcription factors. We next examined the effect of human diabetic adipocytes without or with GSE pre-treatment in co-culture on growth kinetics of colonospheres. Compared to colon CSC alone, presence of adipocytes caused a significant increase in colonospheres formation; however, chronic or acute GSE pre-treatment of adipocytes significantly reduced the booster signals of adipocytes resulting in decreased colonosphere numbers which were comparable to those without adipocytes. Based on these notable biological effects, GSE is a strong candidate agent to be studied further for its potential use against CRC growth and progression under obese conditions. Successful outcomes from such studies would have significant clinical impact on rationalized use of GSE to control obesity-associated human CRC. Citation Format: Sushil Kumar, Dileep Kumar, Komal Raina, Rajesh Agarwal, Chapla Agarwal. Grape seed extract impairs adipocyte-colorectal cancer cell interaction and decreases adipocyte-driven colon cancer stem colonosphere formation. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 4116. doi:10.1158/1538-7445.AM2014-4116