adrenomedullin and Stomach-Neoplasms

Mast cells are prominent components of solid tumors and exhibit distinct phenotypes in different tumor microenvironments. However, their precise mechanism of communication in gastric cancer remains largely unclear. Here, we found that patients with GC showed a significantly higher mast cell infiltration in tumors. Mast cell levels increased with tumor progression and independently predicted reduced overall survival. Tumor-derived adrenomedullin (ADM) induced mast cell degranulation via PI3K-AKT signaling pathway, which effectively promoted the proliferation and inhibited the apoptosis of GC cells in vitro and contributed to the growth and progression of GC tumors in vivo, and the effect could be reversed by blocking interleukin (IL)-17A production from these mast cells. Our results illuminate a novel protumorigenic role and associated mechanism of mast cells in GC, and also provide functional evidence for these mast cells to prevent, and to treat this immunopathogenesis feature of GC.

Topics: Adrenomedullin; Animals; Apoptosis; Cell Line, Tumor; Cell Proliferation; Disease Progression; Exocytosis; Female; Humans; Interleukin-17; Mast Cells; Mice; Mice, Inbred NOD; Mice, SCID; Phosphatidylinositol 3-Kinases; Proto-Oncogene Proteins c-akt; Signal Transduction; Stomach; Stomach Neoplasms; Tumor Microenvironment

Adrenomedullin (ADM), initially identified in human pheochromocytoma, participates in a wide range of physiological and pathological processes, including vasorelaxation, angiogenesis and apoptosis. Recent studies have reported that ADM protected tumor cells against apoptotic cell death via the upregulation of Bcl-2 or the activation of the phosphatidylinositol 3-kinase/Akt pathway. Several studies have also provided evidence that ADM is involved in tumor initiation and progression. However, this has not been shown in gastrointestinal tumors. To investigate the role of ADM in gastrointestinal tumor progression, we determined the expression levels of ADM in 72 cases of stomach cancer and 84 cases of colon cancer and determined whether there was an association between the ADM expression levels and pathological parameters or clinical survival rates. We found that the expression levels of ADM were significantly higher in colon cancers than in matching normal mucosal tissues. In addition, the expression levels of ADM in colon cancers were correlated with cancer stage and clinical survival rate. However, we did not find any significant correlations between ADM expression levels and clinical or pathological parameters in stomach cancers. Taken together, our data strongly suggest that ADM is involved in the progression of colon cancer.

Topics: Adenocarcinoma; Adrenomedullin; Colonic Neoplasms; Humans; Immunohistochemistry; Kaplan-Meier Estimate; Neoplasm Staging; Stomach Neoplasms

Many surface epithelial cells express adrenomedullin, a multifunctional peptide found in a wide number of body and cell systems. Recently, we and others have proposed that adrenomedullin has an important novel role in host defense. This peptide has many properties in common with other cationic antimicrobial peptides, including the human beta-defensins. Upon exposure of human gastric epithelial cells to viable cells of invasive or noninvasive strains of Helicobacter pylori, Escherichia coli, Salmonella enterica, or Streptococcus bovis, a significant increase in adrenomedullin secretion from these cells was demonstrated. Adrenomedullin gene expression was also increased in response to these microorganisms. Similar observations were noted when these cells were incubated with proinflammatory cytokines such as interleukin 1 alpha (IL-1 alpha), IL-6, tumor necrosis factor alpha and lipopolysaccharide. In cultured cells and an animal infection model, increased adrenomedullin peptide and gene expression was demonstrated when exposed to E. coli or Mycobacterium paratuberculosis, respectively. The data suggest there is a strong association between epithelial infection, inflammation, and adrenomedullin expression, which may have clinical relevance. The regulation of adrenomedullin expression may have therapeutic applications, such as improving or enhancing mucosal immunity.

Topics: Adenocarcinoma; Adrenomedullin; Epithelial Cells; Escherichia coli; Gastric Mucosa; Gene Expression Regulation; Helicobacter pylori; Humans; Infections; Inflammation; Interleukin-1; Interleukin-6; Lipopolysaccharides; Mycobacterium avium subsp. paratuberculosis; Peptides; Salmonella enterica; Stomach Neoplasms; Streptococcus bovis; Tumor Cells, Cultured; Tumor Necrosis Factor-alpha