Petra H. Nass

Duodenal reflux produces hyperproliferative epithelial esophagitis—A possible precursor to esophageal adenocarcinoma in the rat

Esophageal reflux of duodenal contents converts a rat nitrosamine esophageal cancer model from squamous cell carcinoma to adenocarcinoma. Further, there was a tendency for male rats to have a higher incidence of cancer than female rats. However, chemical castration with the gonadotropin-releasing hormone analog leuprolide did not protect male or female animals from developing cancer. We have identified an early (6-week) hyperproliferative epithelial cell reaction to duodenal reflux. We carried out experiments to assess the specificity of duodenal reflux in producing the hyperproliferative epithelial precursor lesion. Animals underwent specific surgical procedures to produce esophageal reflux of pure duodenal contents, mixed gastroduodenal, or bland intestinal contents. A hyperproliferative mucosal esophagitis developed in the group with duodenal reflux but not in the other groups. Mucosal thickness in the duodenal reflux group reached seven times that of normal mucosa at 6 weeks. These results suggest that esophageal reflux of duodenal contents plays an important role in the pathogenicity of proliferative esophagitis and the potential development of esophageal adenocarcinoma.

Acidic fibroblast growth factor overexpression partially protects 3T3 fibroblasts from apoptosis induced by synthetic retinoid CD437

Retinoids are proapoptotic compounds with therapeutic potential for treating cancer. We evaluated the apoptotic effect of the novel retinoid CD437, and particularly its relationship to Akt and acidic fibroblast growth factor (aFGF). We hypothesized that the novel synthetic retinoid CD437 would exert its apoptotic effect by reducing the activity of Akt. We further hypothesized that aFGF would protect against CD437 apoptosis by preserving the activity of Akt. Initially we demonstrated that CD437 produces apoptotic cell death in NIHxa03T3 fibroblasts, and that this effect is attenuated in fibroblasts transfected to express aFGF. Next we assessed Akt activity and showed that phospho-Akt is significantly reduced in 3T3 cells exposed to CD437. We showed that this effect is less pronounced in aFGF transfected 3T3 cells. Furthermore, we observed that the addition of exogenous aFGF to 3T3 cells significantly increases Akt phosphorylation. These findings tend to confirm our hypothesis that reduction in Akt activation is a mechanism involved in the apoptotic effect of the retinoid CD437, and that preservation of Akt phosphorylation occurs in response to aFGF and appears to explain the partially protective effect of aFGF for 3T3 cells vis a vis CD437.

Novel nuclear shuttle peptide to increase transfection efficiency in esophageal mucosal cells

The major barrier to successful transfection appears to be passage of the DNA plasmid from the cytoplasm into the cell nucleus. The M9 nuclear localization peptide, a fragment of the naturally occurring heterogeneous nuclear ribonucleoprotein A1, which serves to shuttle messenger RNA across the nuclear membrane, has been proposed as a tool for enhancing transfection efficiency. We tested three different reporter plasmids to assess the ability of M9 to improve transfection efficiency in esophageal mucosal cells. The effect of M9 on the intracellular movement of plasmid was also assessed using fluorescent microscopy to trace rhodamine-labeled plasmid. The M9 nuclear shuttle peptide consistently increased the transfection efficiency. When transfection was carried out with specific plasmids, β-galactosidase enzyme activity, keratinocyte growth factor-1 growth factor levels, and the number of transfected cells expressing growth factor peptides were progressively increased with increasing M9 to plasmid ratios. Fluorescent microscopy demonstrated that the M9 shuttle allowed rhodamine-tagged plasmid to gain access to the nucleus, while it was located exclusively in the cytoplasm without the peptide. The M9 shuttle peptide increases transfection efficiency in esophageal mucosal cells, and therefore may have a useful role in gene therapy applications involving the esophagus.

Use and attitudes towards complementary and alternative medicine therapies among patients at a gastroenterology and hepatology clinic compared to a healthy population

Use and attitudes towards complementary and alternative medicine therapies among patients at a gastroenterology and hepatology clinic compared to a healthy population

Phytoestrogens inhibit cell proliferation and induce apoptosis in esophageal adenocarcinoma cell lines expressing the androgen receptor

cell number, we evaluated cell proliferation by assessing PCNA expression. PEG did not alter PCNA levels. However, PEG treatment resulted in a dose-dependent induction in apoptosis, with 50 mM PEG increasing the apoptosis rate to 84-+3 % (r 2 = 0.78). This data was duplicated using another human colon cancer cell line, CaCo-2. Finally, to investigate potential mechanism(s) of apoptosis, we assessed par-4 expression, a pro-apoptotic protein recently implicated in NSAID-induced apoptosis (Zhang and DuBois Gastroenterology 2000;118:1012-17). Treatment with 50 mM PEG dramatically induced par-4 expression to 17-fold over vehicle (p<O.0001). CONCLUSIONS: We demonstrate, for the first time, that PEG decreased cell number in colon cancer cell line. This occurred apparently through induction of apoptosis rather than alteration of proliferation, potentially by inducing the pro-apoptotic protein, par-4. These findings further support the role of PEG as a chemopreventive agent.