The treatment of cancer cells obtained by blocking cellular metabolism has received a lot of attention recently. Previous studies have demonstrated that Kras mutation-mediated abnormal glucose metabolism would lead to an aberrant cell proliferation in human pancreatic ductal adenocarcinoma (PDAC) cells. Previous literature has suggested that consumption of fish oil is associated with lower risk of pancreatic cancer. In this study, we investigated the anti-cancer effects of docosahexaenoic acid (DHA) in human PDAC cells in vitro and in vivo. Omega-3 polyunsaturated fatty acids (PUFAs) such as DHA and eicosapentaenoic acid (EPA) significantly inhibited the proliferation of human PDAC cells. The actions of DHA were evaluated through an induction of cell cycle arrest at G1 phase and noticed a decreased expression of cyclin A, cyclin E and cyclin B proteins in HPAF-II cells. Moreover, it was found that co-treatment of DHA and gemcitabine (GEM) effectively induced oxidative stress and cell death in HPAF-II cells. Interestingly, DHA leads to an increased oxidative glutathione /reduced glutathione (GSSG/GSH) ratio and induced cell apoptosis in HPAF-II cells. The findings in the study showed that supplementation of GSH or N-Acetyl Cysteine (NAC) could reverse DHA-mediated cell death in HPAF-II cells. Additionally, DHA significantly increased cellular level of cysteine, cellular NADP/NADPH ratio and the expression of cystathionase (CTH) and SLCA11/xCT antiporter proteins in HPAF-II cells. The action of DHA was, in part, associated with the inactivation of STAT3 cascade in HPAF-II cells. Treatment with xCT inhibitors, such as erastin or sulfasalazine (SSZ), inhibited the cell survival ability in DHA-treated HPAF-II cells. DHA also inhibited nucleotide synthesis in HPAF-II cells. It was demonstrated in a mouse-xenograft model that consumption of fish oil significantly inhibited the growth of pancreatic adenocarcinoma and decreased cellular nucleotide level in tumor tissues. Furthermore, fish oil consumption induced an increment of GSSG/GSH ratio, an upregulation of xCT and CTH proteins in tumor tissues. In conclusion, DHA significantly inhibited survival of PDAC cells both in vitro and in vivo through its recently identified novel mode of action, including an increment in the ratio of GSSG/GSH and NADP/NADPH respectively, and promoting reduction in the levels of nucleotide synthesis.

Studies suggest that a low level of circulating human endothelial progenitor cells (EPCs) is a risk factor for ischemic injury and coronary artery disease (CAD). Consumption of S-allylcysteine (SAC) is known to prevent CAD. However, the protective effects of SAC on the ischemic injury are not yet clear. In this study, we examined whether SAC could improve blood flow recovery in ischemic tissues through EPC-mediated neovasculogenesis. The results demonstrate that SAC significantly enhances the neovasculogenesis of EPCs in vitro. The molecular mechanisms for SAC enhancement of neovasculogenesis include the activation of Akt/endothelial nitric oxide synthase signaling cascades. SAC increased the expression of c-kit, β-catenin, cyclin D1, and Cyclin-dependent kinase 4 (CDK4) proteins in EPCs. Daily intake of SAC at dosages of 0.2 and 2 mg/kg body weight significantly enhanced c-kit protein levels in vivo. We conclude that dietary consumption of SAC improves blood flow recovery and prevents ischemic injury by inducing neovasculogenesis in experimental models.

Human pancreatic ductal adenocarcinoma (PDAC) is a deadly cancer type with a very high mortality rate. Inflammatory cytokine such as tumor necrosis factor- alpha (TNF-α) plays a pivotal role in the progression of PDAC. Recently, suppression of cell invasion by preventive agents has received considerable attention in the prevention of metastatic tumors. Several clinical studies suggested that natural forms or analogues of fat-soluble vitamins such as vitamin A and vitamin D can work as anti-cancer agents to inhibit the development of cancer. In this study, our results demonstrated that co-treatment of 13-cis retinoic acid (13-cis RA) and 1,25-dihydroxyvitamin D3 (1,25-VD3) significantly inhibited TNF-α mediated cell invasion in PDAC in vitro. Cotreatment of 13-cis RA and 1,25-VD3 also inhibited TNF-α mediated expression of matrix metalloproteinase-9 (MMP-9) protein through blocking c-Jun N-terminal kinase (JNK) and nuclear factor kappa B (NF-κB) signaling pathways. Our results demonstrated that treatment of TNF-α lead to a decreased expression of tissue inhibitor of metalloproteinase- 3 (TIMP-3) protein and an induction of MMP-9 protein and cell invasion through an upregulation of microRNA-221 (miR-221) in human PDAC cells. Moreover, treatment of SP600125 (a specific inhibitor of JNK pathway) or cotreatment of 13-cis RA and 1,25-VD3 significantly induced a decreased expression of miR-221 and an increased expression of TIMP-3 protein. These results suggest that 13-cis RA and 1,25-VD3 significantly suppress TNF-α mediated cell invasion and therefore potentially act as preventive agents against PDAC.