CD24 Expression Is Increased in 5-Fluorouracil-Treated Esophageal Adenocarcinoma Cells.

The cancer stem cell (CSC) model suggests that there are subsets of cells within a tumor with increased proliferation and self-renewal capacity, which play a key role in therapeutic resistance. The importance of cyclooxygenase-2 (COX-2) in carcinogenesis has been previously established and the use of COX-2 inhibitors as celecoxib has been shown to exert antitumor effects. The present study investigated whether treatment of esophageal adenocarcinoma (EAC) cells with 5-fluorouracil (5-FU) or the growth of tumor spheres increased the proportion of CSCs and also if treatment with celecoxib was able to reduce the putative CSC markers in this tumor. OE19 and OE33 EAC cells surviving 5-FU exposure exhibited an increase in CSC markers CD24 and ABCG2 and also an increased resistance to apoptosis. EAC cell lines had the capacity to form multiple spheres displaying typical CSC functionalities such as self-renewal and increased CD24 levels. In addition, after the induction of differentiation, cancer cells reached levels of CD24 similar to those observed in the parental cells. Treatment with celecoxib alone or in combination with 5-FU also resulted in a reduction of CD24 expression. Moreover, celecoxib inhibited the growth of tumor spheres. These findings showing a reduction in CSC markers induced by celecoxib suggest that the COX-2 inhibitor might be a candidate for combined chemotherapy in the treatment of EAC. However, additional clinical and experimental studies are needed.

Proton Pump Inhibitors Display Antitumor Effects in Barrett's Adenocarcinoma Cells.

Recent evidence has reported that proton pump inhibitors (PPIs) can exert antineoplastic effects through the disruption of pH homeostasis by inhibiting vacuolar ATPase (H+-VATPase), a proton pump overexpressed in several tumor cells, but this aspect has not been deeply investigated in EAC yet. In the present study, the expression of H+-VATPase was assessed through the metaplasia-dysplasia-adenocarcinoma sequence in Barrett's esophagus (BE) and the antineoplastic effects of PPIs and cellular mechanisms involved were evaluated in vitro. H+-VATPase expression was assessed by immunohistochemistry in paraffined-embedded samples or by immunofluorescence in cultured BE and EAC cell lines. Cells were treated with different concentrations of PPIs and parameters of citotoxicity, oxidative stress, and autophagy were evaluated. H+-VATPase expression was found in all biopsies and cell lines evaluated, showing differences in the location of the pump between the cell lines. Esomeprazole inhibited proliferation and cell invasion and induced apoptosis of EAC cells. Production of reactive oxygen species (ROS) seemed to be involved in the cytotoxic effects observed since the addition of N-acetylcysteine significantly reduced esomeprazole-induced apoptosis in EAC cells. Esomeprazole also reduced intracellular pH of tumor cells, whereas only disturbed the mitochondrial membrane potential in OE33 cells. Esomeprazole induced autophagy in both EAC cells, but also triggered a blockade in autophagic flux in the metastatic cell line. These data provide in vitro evidence supporting the potential use of PPIs as novel antineoplastic drugs for EAC and also shed some light on the mechanisms that trigger PPIs cytotoxic effects, which differ upon the cell line evaluated.

Molecular pathogenesis of gastric cancer.

Gastric carcinogenesis is a complex and multifactorial process, in which infection with Helicobacter pylori plays a major role. Additionally, environmental factors as well as genetic susceptibility factors are significant players in gastric cancer (GC) etiology. Gastric cancer development results from the accumulation of multiple genetic and epigenetic changes during the lifetime of the cancer patient that will activate oncogenic and/or inactivate tumor-suppressor pathways. Numerous studies published last year provided new insights into the molecular phenotypes of GC, which will be the main focus of this review. This article also reviews the recent findings on GC tumor-suppressor genes, including putative novel genes. The understanding of the basic mechanisms that underlie gastric carcinogenesis will be of utmost importance for developing strategies of screening, early detection, and treatment of the disease, as most GC patients present with late-stage disease and have poor overall survival.

Relevance of IL-1 and TNF gene polymorphisms on interleukin-1beta and tumor necrosis factor-alpha gastric mucosal production.

We aimed to evaluate the influence of Helicobacter pylori infection and IL-1/TNF gene polymorphisms on interleukin (IL)-1beta and tumor necrosis factor (TNF)-alpha gastric mucosal production. IL-1beta and TNF-alpha levels in homogenized biopsy specimens taken from the antrum and corpus of 81 patients were measured by enzyme-linked immunosorbent assay. Genomic DNA was typed for the IL1B-511, IL1B+3954, variable number of tandem repeat (VNTR) IL1RN, TNFA-308, TNFA-238, LTA NcoI, and LTA Bsi gene polymorphisms by polymerase chain reaction, restriction fragment length polymorphism, and TaqMan assays. H. pylori infection and CagA/VacA antibody status were determined by Western blot. IL-1beta and TNF-alpha protein levels were significantly higher in the gastric antrum of patients infected with H. pylori compared with uninfected patients [9.54 (5.07-16.28) vs. 4.55 (3.69-8.28) pg IL-1beta/mg protein, p = 0.004, and 1.5 (0.7-2.71) vs. 0.63 (0.3-1.26) pg TNF-alpha/mg protein, p = 0.001]. Among H. pylori-infected individuals, carriers of the IL1RN*2 allele had significantly higher antrum mucosal IL-1beta levels than noncarriers [15.97 (9.59-26.6) vs. 10.08 (7.72-13.33), p = 0.008]. No association between gastric mucosal TNF-alpha levels and genotypes of the TNFA and LTA gene polymorphisms was reported. Our results indicate that the VNTR polymorphism of the IL1RN gene influences IL-1beta gastric mucosal production in patients infected with H. pylori.

Lack of association of IL-12 p40 gene polymorphism with peptic ulcer disease.

Interleukin 12 (IL-12) is a proinflammatory cytokine composed by two chains, p40 and p35, that plays a key role in the promotion of a Th1 immune response in the gastrointestinal mucosa. An enhanced expression of IL-12 mRNA in gastric mucosa has been reported in individuals infected by Helicobacter pylori. The aim of our study was to assess whether a functional polymorphism located at position 1188 (A-->C) of the IL-12 p40 (IL12B) gene is associated with the susceptibility and clinical features of peptic ulcer disease. Genotyping of 184 unrelated white Spanish patients with peptic ulcer and 107 healthy controls was performed by polymerase chain reaction and restriction fragment length polymorphism. Helicobacter pylori status and nonsteroidal antiinflammatory drugs use were studied in patients and controls. There were no significant differences in carriage, genotype, and allele frequencies of the IL-12 p40 gene polymorphism between patients with peptic ulcer and controls. Moreover, no differences were found with respect to the localization of the ulcer, Helicobacter pylori status, nonsteroidal antiinflammatory drug use, age, sex, bleeding episodes, and family history of peptic ulcer. Our data reveal that the IL12B 1188 (A-->C) gene polymorphism is not involved in defining the genetic basis of the susceptibility to and final outcome of peptic ulcer disease.