Modulation of apoptosis, cell cycle, and MAPK pathways in human SEG-1 esophageal cells by a cranberry extract.

B102

Over the past 20 years, esophageal adenocarcinoma (EAC) has increased dramatically in the western world and is currently the seventh most common cause of cancer mortality among US males. Diagnosis often occurs late in the course of EAC pathogenesis contributing to the poor overall five-year survival rate of 14.9%. Esophageal cancer is the third most deadly malignancy supporting the crucial need for improved preventative and treatment strategies. The basis for the increase in EAC remains to be fully elucidated, but has been linked to gastroesophageal reflux disease (GERD), a high fat diet, obesity, and a limited number of dietary factors. Recently, cranberry extracts have been shown have chemopreventive potential when evaluated in breast, colon and prostate cancer cell lines. In addition, preliminary work in our lab showed that a cranberry extract inhibited cell proliferation and induced G1 cell cycle arrest in EAC cells. The purpose of this study was to investigate the potential mechanisms associated with chemoprevention by cranberry proanthocyanidins (PAC) in SEG-1 esophageal adenocarcinoma cells. SEG-1 cells were treated either with 50 μg/ml of PAC or vehicle (veh) and global gene expression arrays were employed to explore potential mechanisms of chemoprotection. RNA was isolated from PAC or veh treated SEG-1 cells six hours post-treatment. Total RNA was extracted, cDNA generated, transcribed into cRNA, and hybridized to Affymetrix human U133 2.0 plus oligonucleotide microarrays to detect PAC-induced changes in gene expression. WEDGE++ analysis was conducted to determine significant differentially expressed genes by treatment. Next, EASE analysis was conducted to identify key biological themes altered following PAC treatment. Microarray findings and real-time PCR validation supported that PAC treatment upregulated the apoptotic genes BAK1, BID, BCL2L1, DFFA, TNFRSF10A, TP73, TRADD and PAC down regulated APAF1, BAG4, FAS, and TRAF2. PAC treatment of SEG-1 cells predominately down regulated cell cycle pathway markers including PCNA, Ki67, CHEK1, CDCs, and multiple Cyclins. In addition, PAC treatment significantly down regulated genes involved in MAPK signaling, a pathway recently reported to be activated by acid and bile exposure, as occurs with GERD. Since aberrant signaling has been implicated in carcinogenesis, other cellular pathways modulated by PAC will be further investigated, including WNT, TGF-Beta, and Insulin signaling. Our results support that cranberry PAC's significantly alter multiple processes associated with esophageal cancer progression and further studies are warranted to assess the cancer inhibitory potential of this extract in vivo.