Abstract B67: In vitro and in vivo inhibitory effects of cranberry proanthocyanidins against esophageal adenocarcinoma

Abstract

Abstract This study investigated the cancer inhibitory potential of a proanthocyanidin rich cranberry extract utilizing a panel of authenticated human esophageal adenocarcinoma cell lines (EAC), a nude mouse xenograft model, and the rat esophagogastrodoudenal anastomosis (EGDA) model of EAC. PACs effects on cell morphology, global gene expression, phase of cell cycle, and cell death induction via apoptosis, autophagy, and necrosis were evaluated. Methods included RapidDiff and MDC staining, Annexin/PI and BrdU staining with flow cytometric evaluation, transmission electron microscopy (TEM), protein evaluation utilizing standard Western blot techniques, and validation of global gene expression changes by real-time PCR. PAC treatment [50-100µg/ml] of EAC cancer cell lines resulted in significant increases in apoptosis, autophagy and necrosis. Differential cell death induction was noted based upon the cell lines resistance to a bile/acid cocktail mimicking acid exposure in humans as well as the status of the apoptotic and autophagic machinery of the select cell line. PACs cell death inducing capacity correlated with altered MAPKinase signaling as evidenced by activation of P-p38 and P-JNK and inhibition of P-ERK1/2. PAC treatment induced other proapoptotic markers including cleaved PARP, BAK1, BAX, and cytochrome C, but in a cell line dependent manner. Mild increases in Beclin-1 were noted following PAC treatment, as were significant increases in LC3II, a marker of autophagasome formation which occurs during autophagy induction. Results were confirmed by TEM and MDC staining. PAC induced cell cycle arrest at the G2/M transition, increased the percent of cells in G1, caused an S-phase delay and increased P21 levels in all three cell lines. PAC administration significantly inhibited the growth of OE19 xenografts via modulation of cell cycle and MAPK signaling pathways. Oral gavage of PAC [250µg/mouse] six times a week to nude mice resulted in a 67% decrease in OE19 tumor volume, increased cytochrome C protein levels and decreased levels of P-ERK1/2, cyclin A, PCNA, and CD31 in PAC treated tumors compared to vehicle treated tumors. Lastly, a four week pilot study was performed to evaluate the safety of daily administration of PAC in the rodent EGDA model. PAC appeared well tolerated given the average daily dose of 450µg/rat/day as evidenced by normal body weight and food consumption, serology profiles and histopathology of the major organs. Further long-term studies are planned to more fully access the chemopreventive potential of PAC against esophageal adenocarcinoma and premalignancy utilizing the clinically relevant rat EGDA surgical model. Citation Information: Cancer Prev Res 2010;3(12 Suppl):B67.