Search

Background & Aims TP53 mutations underlie Barrett’s esophagus (BE) progression to dysplasia and cancer. During BE progression, the ubiquitin ligase (E3) RNF128/GRAIL switches expression from isoform 2 (Iso2) to Iso1, stabilizing mutant p53. However, the ubiquitin-conjugating enzyme (E2) that partners with Iso1 to stabilize mutant p53 is unknown. Methods Single-cell RNA sequencing of paired normal esophagus and BE tissues identified candidate E2s, further investigated in expression data from BE to esophageal adenocarcinoma (EAC) progression samples. Biochemical and cellular studies helped clarify the role of RNF128-E2 on mutant p53 stability. Results The UBE2D family member 2D3 (UBCH5C) is the most abundant E2 in normal esophagus. However, during BE to EAC progression, loss of UBE2D3 copy number and reduced expression of RNF128 Iso2 were noted, 2 known p53 degraders. In contrast, expression of UBE2D1 (UBCH5A) and RNF128 Iso1 in dysplastic BE and EAC forms an inactive E2–E3 complex, stabilizing mutant p53. To destabilize mutant p53, we targeted RNF128 Iso1 either by mutating asparagine (N48, 59, and 101) residues to block glycosylation to facilitate β-TrCP1–mediated degradation or by mutating proline (P54 and 105) residues to restore p53 polyubiquitinating ability. In addition, either loss of UBCH5A catalytic activity, or disruption of the Iso1-UBCH5A interaction promoted Iso1 loss. Consequently, overexpression of either catalytically dead or Iso1-binding–deficient UBCH5A mutants destabilized Iso1 to degrade mutant p53, thus compromising the clonogenic survival of mutant p53-dependent BE cells. Conclusions Loss of RNF128 Iso2–UBCH5C and persistence of the Iso1–UBCH5A complex favors mutant p53 stability to promote BE cell survival. Therefore, targeting of Iso1-UBCH5A may provide a novel therapeutic strategy to prevent BE progression., Graphical abstract

Background and Aims Visceral hypersensitivity is common in patients with irritable bowel syndrome (IBS). We investigated whether inflammatory molecules, such as histamine and proteases, activate prostaglandin-endoperoxide synthase 2 (also called COX2) to increase the synthesis of prostaglandin E2 (PGE2) by mast cells, which activates the receptor PTGER2 (also called EP2) in the dorsal root ganglia to promote visceral hypersensitivity. Methods We used an enzyme-linked immunosorbent assay to measure levels of spontaneous release of molecules from mast cells in colonic mucosa from patients with IBS with diarrhea (IBS-D; 18 women and 5 men; aged 28–60 years), healthy individuals (controls, n = 24), mice, and rats. We measured visceromotor responses to colorectal distension in rodents after intracolonic administration of colon biopsy supernatants, histamine, PGE2, a small interfering RNA against EP2, or an agonist of F2R like trypsin receptor 1 (F2RL1, also called protease-activated receptor 2 [PAR2]). We investigated the role of COX2, produced by mast cells, in mediation of visceral hypersensitivity using mice with the Y385F substitution in Ptgs2 (Ptgs2Y385F mice), mast cell–deficient (W/WV) mice, and W/WV mice given injections of mast cells derived from wild-type or Ptgs2Y385F mice. Results Colon biopsies from patients with IBS-D had increased levels of PGE2, based on enzyme-linked immunosorbent assay, and COX2 messenger RNA and protein, compared with control biopsies. Immunohistochemistry showed that most of the COX2 was in mast cells. Intracolonic infusions of rats with IBS-D biopsy supernatants generated a 3- to 4-fold increase in visceromotor responses to colorectal distension; this was associated with significant increases in PGE2, histamine, and tryptase in the colonic mucosa. These increases were prevented by a mast cell stabilizer, COX2 inhibitor, or knockdown of EP2. Intracolonic administration of supernatants from biopsies of patients with IBS-D failed to induce visceral hypersensitivity or increase the level of PGE2 in W/WV and Ptgs2Y385F mice. Reconstitution of mast cells in W/WV mice restored the visceral hypersensitivity response. Conclusions Abnormal synthesis of PGE2 by colonic mast cells appears to induce visceral hypersensitivity in patients with IBS-D.

Background & Aims Dysplasia is a premalignant condition in Barrett's esophagus that is difficult to detect on endoscopy because of its flat architecture and patchy distribution. Peptides are promising for use as novel molecular probes that identify cell surface targets unique to disease and can be fluorescence-labeled for detection. We aim to select and validate an affinity peptide that binds to esophageal dysplasia for future clinical studies. Methods Peptide selection was performed using phage display by removing nonspecific binders using Q-hTERT (intestinal metaplasia) cells and achieving specific binding against OE33 (esophageal adenocarcinoma) cells. Selective binding was confirmed on bound phage counts, enzyme-linked immunosorbent assay (ELISA), flow cytometry, competitive inhibition, and fluorescence microscopy. On stereomicroscopy, specific peptide binding to dysplasia on endoscopically resected specimens was assessed by rigorous registration of fluorescence intensity to histology in 1-mm intervals. Results The peptide sequence SNFYMPL was selected and showed preferential binding to target cells. Reduced binding was observed on competition with unlabeled peptide in a dose-dependent manner, an affinity of K d = 164 nmol/L was measured, and peptide binding to the surface of OE33 cells was validated on fluorescence microscopy. On esophageal specimens (n = 12), the fluorescence intensity (mean ± SEM) in 1-mm intervals classified histologically as squamous (n = 145), intestinal metaplasia (n = 83), dysplasia (n = 61), and gastric mucosa (n = 69) was 46.5±1.6, 62.3±5.8, 100.0±9.0, and 42.4 ± 3.0 arb units, respectively. Conclusions The peptide sequence SNFYMPL binds specifically to dysplasia in Barrett's esophagus and can be fluorescence labeled to target premalignant mucosa on imaging.

Background: Patients with irritable bowel syndrome (IBS) suffer from abdominal pain and associated constipation, diarrhea, and bloating. Some IBS patients (~35%) have visceral hypersensitivity to noxious experimental stimuli (e.g., colonic distension). We previously reported that colonic NMDA receptor signaling in IBS patients may be an underlying mechanism leading to visceral hypersensitivity that is reversed with Dextromethorphan (J Pain 2012;13:901-9). The current study was performed to determine if down regulation of in vivo NMDA receptor signaling via upregulation of miR-23a using miRNA mimics reverses visceral hypersensitivity in an IBS animal model. Methods: Male rats (n=12) received onehour water avoidance (WA) stress per day, for 10 consecutive days to induce visceral hypersensitivity as measured by colonic distension using a barostat. Intrathecal injection of miR-23a mimics (n=6 rats) or miRNA control (n=6 rats) was then performed and visceral hypersensitivity was measured 7 days later following injections. Following colonic barostat testing, all rats were sacrificed to measure colonic NMDA receptors and miR-23a expression using fluorescence in situ hybridization (FISH) using tyramide signal amplification (TSA) technology. Results: Rats treated with intrathecal injection of miR-23a mimics had decreased visceral hypersensitivity compared to rats that received intrathecal control miRNA (p

Diaz and colleagues have carefully studied the effects of omeprazole on the expression of cytochrome P-450 in primary cultures of human hepatocytes. When omeprazole was added to the culture medium in varying concentrations, there was an increase in P-450IA2 protein and mRNA concentrations, an increase in de novo synthesis of P-450IA2 protein, and an increase in microsomal catalytic activities characteristic of P-450IA2 (phenacetin deethylase and acetanilide hydroxylase). Omeprazole treatment also resulted in an increase in both enzymatic activity characteristic of P-450IA1 (ethoxyresorufin deethylase and benzpyrene hydroxylase) and concentration of P-450IA1 mRNA. In contrast, omeprazole appeared to have no significant effect on expression of other P-450s within the P-450II or P-450III families in the hepatocytes. To validate these in vitro observations, liver biopsy specimens were obtained from five patients before and after a 4-day course of pharmacological doses of omeprazole. In each patient, omeprazole treatment appeared to result in a two- to eightfold increase in P-450IA2 immunoreactive protein and P-450IA1 and P-450IA2 enzymatic activities. The authors conclude that omeprazole is an inducer of P-450IA2 and probably P-450IA1 in human liver. Induction of these enzymes could potentiate the bioactivation of carcinogens or the hepatotoxicity of some drugs such as acetaminophen.