Immunohistochemical evidence that culture in the high aspect rotating vessel can up-regulate hormone expression in growth dedifferentiated PHHI-derived islet cells.

Islet cells derived from patients with persistent hyperinsulinemic hypoglycemia of infancy (PHHI) have the ability to grow readily in simple culture media. However, as with primary islets and cell lines, they lose hormone expression upon growth. In this study, we have investigated the role of three-dimensional cell-to-cell contact in the reinitiation of hormone expression in growth dedifferentiated PHHI-derived cells. Two main methods of cell aggregation were studied; the promotion of pseudoislets through petri dish culture and the creation of cell aggregates in the microgravity environment of the high aspect ratio vessel (HARV). Immunohistochemical analysis and ELISA assay showed that petri dish culture did not re-establish endocrine expression in any of the five cultures tested. However, through HARV technology, we have demonstrated that it is possible to reactivate insulin, glucagon, somatostatin, and GAD expression in PHHI-derived cells that had previously stopped expressing these markers. These results indicate that the unique environment of the HARV can be conducive to the upregulation of endocrine expression of islet-derived cells and optimization of culture conditions may prove useful in the sphere of beta cell proliferation.

The rice bran constituent tricin potently inhibits cyclooxygenase enzymes and interferes with intestinal carcinogenesis in ApcMin mice.

While brown rice is a staple dietary constituent in Asia, rice consumed in the Western world is generally white, obtained from brown rice by removal of the bran. Rice bran contains the flavone tricin, which has been shown to inhibit colon cancer cell growth. We tested the hypothesis that tricin interferes with adenoma formation in the Apc(Min) mouse. Mice received tricin (0.2%) in their American Institute of Nutrition 93G diet throughout their postweaning life span (4-18 weeks). Consumption of tricin reduced numbers of intestinal adenomas by 33% (P < 0.05) compared with mice on control diet. We explored whether tricin may exert its effect via inhibition of cyclooxygenase (COX) enzymes. Its effect on COX activity was assessed in purified enzyme preparations in vitro and its ability to reduce prostaglandin E(2) (PGE(2)) levels in human colon-derived human colon epithelial cell (HCEC) and HCA-7 cells in vitro and in Apc(Min) mice in vivo. Tricin inhibited activity of purified COX-1 and COX-2 enzyme preparations with IC(50) values of approximately 1 micromol/L. At 5 micromol/L, it reduced PGE(2) production in HCEC or HCA-7 cells by 36% (P < 0.01) and 35% (P < 0.05), respectively. COX-2 expression was reduced by tricin weakly in HCEC and unaffected in HCA-7 cells. PGE(2) levels in the small intestinal mucosa and blood of Apc(Min) mice that had received tricin were reduced by 34% (P < 0.01) and 40% (P < 0.05), respectively, compared with control mice. The results suggest that tricin should be further evaluated as a putative colorectal cancer chemopreventive agent.

Phase I clinical trial of oral curcumin: biomarkers of systemic activity and compliance.

Curcumin, a polyphenolic antioxidant derived from a dietary spice, exhibits anticancer activity in rodents and in humans. Its efficacy appears to be related to induction of glutathione S-transferase enzymes, inhibition of prostaglandin E(2) (PGE(2)) production, or suppression of oxidative DNA adduct (M(1)G) formation. We designed a dose-escalation study to explore the pharmacology of curcumin in humans. Fifteen patients with advanced colorectal cancer refractory to standard chemotherapies consumed capsules compatible with curcumin doses between 0.45 and 3.6 g daily for up to 4 months. Levels of curcumin and its metabolites in plasma, urine, and feces were analyzed by high-pressure liquid chromatography and mass spectrometry. Three biomarkers of the potential activity of curcumin were translated from preclinical models and measured in patient blood leukocytes: glutathione S-transferase activity, levels of M(1)G, and PGE(2) production induced ex vivo. Dose-limiting toxicity was not observed. Curcumin and its glucuronide and sulfate metabolites were detected in plasma in the 10 nmol/L range and in urine. A daily dose of 3.6 g curcumin engendered 62% and 57% decreases in inducible PGE(2) production in blood samples taken 1 hour after dose on days 1 and 29, respectively, of treatment compared with levels observed immediately predose (P < 0.05). A daily oral dose of 3.6 g of curcumin is advocated for Phase II evaluation in the prevention or treatment of cancers outside the gastrointestinal tract. PGE(2) production in blood and target tissue may indicate biological activity. Levels of curcumin and its metabolites in the urine can be used to assess general compliance.