Carcinogenesis of Helicobacter pylori.
Helicobacter infection is the leading cause of gastric cancer worldwide. Infection with this ubiquitous bacterium incites a chronic active immune response that persists for the life of the host, in the absence of antibiotic-induced eradication. It is the combination of bacterial factors, environmental insults, and the host immune response that drives the initiation and progression of mucosal atrophy, metaplasia, and dysplasia toward gastric cancer. Although it may seem intuitively obvious that removing the offending organism would negate the cancer risk, this approach is neither feasible (half of the world harbors this infection) nor is it straightforward. Most patients are infected in childhood, and present with various degrees of mucosal damage before any therapy. This review outlines the histologic progression of human Helicobacter infection from the early stages of inflammation through the development of metaplasia, dysplasia, and, finally, cancer. The effects of dietary and bacterial eradication therapy on disease progression and lesion reversibility are reviewed within the context of population studies and compared between study designs and populations tested. Eradication studies in the mouse model of infection prevents the formation of gastric cancer, and allows regression of established lesions, providing a useful model to study interaction between bacterium, environment, and host, without the difficulties inherent in human population studies. Recent advances in identifying the bone marrow-derived stem cell as the cell of origin of Helicobacter-induced gastric cancer in the murine model are discussed and interpreted in the context of human disease, and implications for future treatment are discussed.
Correa
Pelayo
P
Division of Gastroenterology, Hepatology and Nutrition, Vanderbilt University Medical Center, Nashville, Tennessee, USA.
Houghton
Jeanmarie
J
D000818:Animals; D000900:Anti-Bacterial Agents / Q000494:pharmacology / Q000627:therapeutic use; D016588:Anticarcinogenic Agents / Q000494:pharmacology / Q000627:therapeutic use; D000975:Antioxidants / Q000494:pharmacology / Q000627:therapeutic use; D001854:Bone Marrow Cells / Q000382:microbiology / Q000473:pathology; D002454:Cell Differentiation; D049109:Cell Proliferation; D002471:Cell Transformation, Neoplastic / Q000187:drug effects / Q000378:metabolism / Q000473:pathology*; D004195:Disease Models, Animal; D018450:Disease Progression; D005753:Gastric Mucosa / Q000187:drug effects / Q000378:metabolism / Q000382:microbiology* / Q000473:pathology; D016481:Helicobacter Infections / Q000150:complications* / Q000188:drug therapy / Q000378:metabolism / Q000382:microbiology / Q000473:pathology; D016480:Helicobacter pylori; D006801:Humans; D051379:Mice; D008810:Mice, Inbred C57BL; D014411:Neoplastic Stem Cells / Q000382:microbiology / Q000473:pathology; D011230:Precancerous Conditions / Q000378:metabolism / Q000382:microbiology* / Q000473:pathology / Q000517:prevention & control; D015398:Signal Transduction; D013274:Stomach Neoplasms / Q000378:metabolism / Q000382:microbiology* / Q000473:pathology / Q000517:prevention & control
D000900:Anti-Bacterial Agents; D016588:Anticarcinogenic Agents; D000975:Antioxidants