3-nitrotyrosine and Barrett-Esophagus

The high concentration of nitric oxide (NO) around the gastro-esophageal junction (GEJ) might play an important role in the development of Barrett's esophagus (BE), a precursor of Barrett's adenocarcimona. Although previous studies revealed that the expression of caudal-type homeobox 2 (CDX2), an important marker of BE, might be induced through Epidermal Growth Factor Receptor (EGFR), the roles of NO in this signal transduction remain unclear.. First, we investigated the expressions of EGFR, CDX2 and nitrotyrosine by immunohistochemical study for BE and squamous epithelium of human specimens. Second, we studied the effect of peroxynitrite, peroxynitrite stimulator, SIN-1, or NO donor, NOC7, on the expression of phosphorylated EGFR and CDX2 in KYSE30, an EGFR-rich human esophageal squamous cell carcinoma cell-line. Specific inhibitors for EGFR, AG1478 and small interfering RNA for EGFR (EGFR-siRNA) were employed to elucidate the role of EGFR in the induction of CDX2.. The immunohistochemical study revealed that the expressions of EGFR, CDX2 and nitrotyrosine in BE were stronger than those in squamous epithelium with positive correlations. Exposure to peroxynitrite, SIN-1 or NOC7 induced EGFR phosphorylation and CDX2 expression in dose- and time-dependent manners. Both EGFR phosphorylation and CDX2 induction were significantly diminished by AG 1478 and EGFR-siRNA.. We revealed for the first time that extrinsic NO might directly induce CDX2 expression through EGFR phosphorylation. We suggested that NO had an important role in the development of BE from squamous epithelium around GEJ.

Topics: Barrett Esophagus; Carcinoma, Squamous Cell; CDX2 Transcription Factor; Cell Line, Tumor; Epithelium; ErbB Receptors; Esophagogastric Junction; Homeodomain Proteins; Humans; Immunohistochemistry; Metaplasia; Nitric Oxide; Phosphorylation; Tyrosine

The molecular and cellular mechanisms linking chronic inflammation and gastrointestinal malignancy are not known with certainty.. To investigate changes in potential causative factors during progression of esophagus cancer in a population living in high-risk area in Iran.. Formalin-fixed, paraffin-embedded esophageal specimens (n=87) from patients with gastroesophageal reflux disease (GERD), Barrett's metaplasia, adenocarcinoma (ADC) and squamous cells carcinoma (SCC) were collected based on their pathological diagnosis.. Immunohistochemical (IHC) technique was used to study tissue accumulation of P53, P21, cyclooxygenase-2 (COX-2), glutathione S-transferase-P (GST-Pi) and nitrotyrosine (NT) in patients and controls.. P53 expression was not detected in esophageal tissues from normal and GERD samples, whereas it was found positive in Barrett's, ADC, and SCC samples. P21 positive sample was relatively higher in ADC patients as compared to that in SCC (ADC: 52.6%; SCC: 25%). GST-Pi expression was equally accumulated in all the samples. NT was predominantly expressed in ADC (72.7%). COX-2 expression was significantly higher in Barrett's (60.0%) and ADC (66.6%) as compared to that in GERD, SCC and normal. These data were further confirmed by detecting the scores of immunostainings in all the positive samples.. The pathological changes in ADC and SCC samples which were associated with increasing frequency of NT and COX-2 provides further evidence for involvement of these inflammatory factors in progression of esophagus cancer.

Topics: Adenocarcinoma; Adult; Aged; Aged, 80 and over; Barrett Esophagus; Biomarkers, Tumor; Carcinoma, Squamous Cell; Case-Control Studies; Cyclin-Dependent Kinase Inhibitor p21; Cyclooxygenase 2; Disease Progression; Esophageal Neoplasms; Esophagus; Female; Gastroesophageal Reflux; Glutathione S-Transferase pi; Humans; Immunohistochemistry; Iran; Male; Middle Aged; Precancerous Conditions; Tumor Suppressor Protein p53; Tyrosine; Young Adult

Nitric oxide (NO) has been implicated as a potential causative factor for endogenous p53 mutations in gastrointestinal malignancy. To investigate the role of NO in esophageal adenocarcinoma (EADC), we studied patterns of p53 mutations, expression of inducible nitric oxide synthase (iNOS) and the tissue accumulation of nitrotyrosine (NTS), a stable reaction product of NO and a marker for cellular protein damage, in human premalignant and malignant esophageal epithelia. Tissues were obtained from patients with gastroesophageal reflux disease (GERD)-induced esophagitis (n = 76), Barrett's esophagus (BE; n = 119) and primary EADC (n = 54). DNA sequencing was used to characterize p53 mutations, RT-PCR to study iNOS mRNA expression, and immunohistochemistry to study NTS. Relative to self-matched normal epithelia, a progressive increase in iNOS mRNA expression was seen in GERD (30%; 23/76), BE (48%; 57/119), and EADC (63%; 34/54) tissues (P < 0.001). Among patients with EADC, elevated levels of NTS immunoreactivity were more frequent in tumors with p53 mutations (11/21; 52%) compared with tumors with wild-type p53 (9/33; 27%; P = 0.063), and specifically in tumors with p53 mutations at CpG dinucleotides (10/12; 83%) compared with non-CpG p53 mutations (1/9; 11%; P = 0.008). The increasing frequency of iNOS (mRNA) overexpression in GERD, BE and EADC supports the hypothesis that an active inflammatory process, most likely a consequence of GERD, underlies molecular progression to EADC. The highly significant association between NTS, reflecting chronic NO-induced cellular protein damage, and endogenous p53 mutations at CpG dinucleotides, provides further evidence for a molecular link between chronic inflammation and esophageal malignancy.

Topics: Adenocarcinoma; Adolescent; Adult; Aged; Aged, 80 and over; Barrett Esophagus; Chronic Disease; Esophageal Neoplasms; Female; Genes, p53; Humans; Inflammation Mediators; Male; Middle Aged; Nitric Oxide; Nitric Oxide Synthase Type II; Point Mutation; Tumor Suppressor Protein p53; Tyrosine

Experimental studies suggest that free radicals are involved in acid and pepsin-induced damage of esophageal mucosa. The profile and balance between free radicals and antioxidant systems in human esophagitis are unknown.. Superoxide anion and its powerful oxidant reaction with nitric oxide (peroxynitrite) generation were determined in esophageal mucosal biopsies from 101 patients with different gastro-esophageal reflux diseases and 28 controls. Activity of both superoxide dismutase (SOD) and catalase, and reduced glutathione (GSH) levels, were also assessed. Expression of Cu, ZnSOD, MnSOD and tyrosine-nitrated MnSOD were analyzed by Western blot and/or immunohistochemistry.. The highest levels of superoxide anion generation were found in patients with severe lesions of esophagitis. Peroxynitrite generation was intense in Barrett's biopsies, weaker in esophagitis and absent/weak in normal mucosa. Expression of Cu, ZnSOD and MnSOD isoforms were present in normal mucosa and increased according to the severity of the lesion, reaching the highest level in Barrett's esophagus. However, SOD mucosal activity significantly decreased in patients with esophagitis and Barrett's esophagus, which was, at least in part, due to nitration of its tyrosine residues. Catalase activity and GSH levels were significantly increased in mucosal specimens from patients with esophagitis and/or Barrett's esophagus.. A decrease in SOD antioxidant activity leading to increased mucosal levels of superoxide anion and peroxynitrite radicals may contribute to the development of esophageal damage and Barrett's esophagus in patients with gastroesophageal reflux. Administration of SOD may be a therapeutic target in the treatment of patients with esophagitis and Barrett's esophagus.

Topics: Adult; Aged; Aged, 80 and over; Barrett Esophagus; Esophagitis; Female; Free Radicals; Gastroesophageal Reflux; Glutathione; Humans; Male; Middle Aged; Oxidoreductases; Reactive Oxygen Species; Superoxide Dismutase; Tyrosine