Inflammatory disease of the bowel: the risk of cancer

Development of mucinous adenocarcinoma in chronic Crohn's disease fistulae without luminal involvement

A patient with Crohn's disease who developed mucinous adenocarcinoma in chronic fistulae is reported. Malignancy may complicate chronic nonhealing Crohn's sinus tracts and fistulae, even with no mucosal involvement by carcinoma. Persistent non-remitting perianal induration and pain should alert the physician to the possibility of underlying malignancy. Prompt examination under anesthesia and biopsy or fine-needle aspiration may facilitate diagnosis and therapy of the carcinoma at an early stage.

Vitamin E protects mononuclear leucocyte DNA against damage mediated by phagocyte-derived oxidants

The protective effects of physiological concentrations (3-12.5 micrograms/ml) of vitamin E (VE, dl-alpha-tocopherol) on the formation of DNA single-strand breaks in mononuclear leukocytes (MNL) in close proximity to activated phagocytes have been investigated in vitro. Human neutrophils, activated by phorbol myristate acetate (PMA), induced DNA-strand breaks in neighbouring lymphocytes. Vitamin E caused dose-related protection of MNL DNA against phagocyte-mediated oxidative damage. This apparently novel protective activity of vitamin E is due primarily to the inhibitory effects of this agent on the generation of reactive oxidants by activated neutrophils and is apparently unrelated to the classical oxidant-scavenging properties of VE.

Hypochlorous acid potentiates hydrogen peroxide-mediated DNA-strand breaks in human mononuclear leucocytes

In this study the formation of DNA single-strand breaks in MNL in close proximity to activated phagocytes, or in contact with added H2O2 and/or HOCl, were evaluated. Neutrophils activated by phorbol myristate acetate (PMA), induced DNA-strand breaks in neighboring lymphocytes which increased after 1-2 h incubation in a repair medium. These DNA-strand breaks could be prevented by the addition of catalase or substitution of the neutrophils with cells from a patient with chronic granulomatous disease. Inclusion of the myeloperoxidase (MPO) inhibitor, sodium azide (NaN3), to the system was associated with less damage after 1-2 h incubation and a faster repair rate. Exposure of MNL to added reagent H2O2 (12-100 microM) was also accompanied by DNA damage. Addition of reagent HOCl (3-25 microM) did not induce any DNA-strand breaks. However, when combined with H2O2 (12.5 microM), HOCl increased H2O2-mediated DNA damage and compromised the repair process. Interactions between the phagocyte-derived reactive oxidants H2O2 and HOCl are probably involved in the etiology of inflammation-related cancer.

Inactivation of poly (ADP-ribose) polymerase by hypochlorous acid

The effects of the phagocyte-derived reactive oxidants hydrogen peroxide (H2O2) and hypochlorous acid (HOC1) on the activity of poly(ADP-ribose) polymerase (pADP RP), an enzyme involved in DNA repair, and on the induction and repair of DNA strand breaks in human mononuclear leukocytes (MNL) have been investigated in vitro. Exposure of MNL to reagent H2O2 was accompanied by DNA damage and activation of pADP RP. Addition of reagent HOCl (25 microM) was not associated with DNA strand breaks. However, when combined with 150 microM H2O2, HOCl potentiated H2O2-mediated DNA damage, and compromised the repair process. Furthermore, HOCl caused a dose-related decrease in the activity of pADP RP in both control and H2O2-exposed MNL. Interactions between the phagocyte-derived reactive oxidants H2O2 and HOCl are probably involved in the etiology of inflammation-related cancer.

Damage to the bases in DNA induced by stimulated human neutrophils

Leukocyte-induced DNA damage may partially account for the known association between chronic inflammation and malignancy. Since elucidation of the chemical nature of leukocyte-induced DNA damage may enhance our understanding of the mechanisms underlying leukocyte-induced DNA damage and the carcinogenesis associated with inflammation, the present study was undertaken to characterize the chemical modifications that occur in DNA exposed to stimulated human neutrophils. Calf thymus DNA was exposed to phorbol myristate acetate (PMA)-stimulated neutrophils in the presence or absence of exogenously added iron ions. DNA samples were subsequently hydrolyzed, derivatized and analyzed by gas chromatography-mass spectrometry with selected-ion monitoring. A variety of base modifications including cytosine glycol, thymine glycol, 4,6-diamino-5-formamidopyrimidine, 8-hydroxyadenine, 2,6-diamino-4-hydroxy-5-formamidopyrimidine, and 8-hydroxyguanine were identified. The yield of these various base products was increased by the addition of iron ions. Specifically, in the presence of physiologic quantities of iron ions, approximately 7 of every 1,000 DNA bases were modified. Addition of the superoxide anion scavenger, superoxide dismutase, the hydrogen peroxide scavenger, catalase, the hydroxyl scavenger, dimethylsulfoxide, or the iron chelator, deferoxamine, to DNA mixtures containing PMA, neutrophils, and iron ions, greatly decreased the yield of the damaged DNA base products. Our results indicate that stimulated human neutrophils can damage each of the four bases in DNA. It is likely that hydroxyl radical, generated via an iron catalyzed Haber-Weiss reaction, mediates neutrophil-induced DNA base damage, since: (a) the chemical structure of neutrophil-induced DNA base damage is consistent with a hydroxyl radical-mediated mechanism, (b) hydroxyl radical generated via ionizing radiation in aqueous solution produces DNA base modifications that are identical to neutrophil-induced DNA base modifications, (c) iron ions increase neutrophil-induced DNA base damage, and (d) iron chelators or scavengers of superoxide anion, hydrogen peroxide or hydroxyl radical decrease neutrophil-induced DNA base damage.

Anal carcinoma in patients with Crohn's disease

Three patients with Crohn's disease and carcinoma of the anus are reported and compared to a group of patients with anal cancer and no inflammatory bowel disease. The three patients with Crohn's disease were relatively young women with significant perianal disease. There were two squamous cell lesions and one cloacogenic tumor in this group. The relative incidence of anal cancer as a proportion of all colorectal cancer, in patients with Crohn's disease (14%) was found to be significantly higher than the incidence of anal cancer in patients without inflammatory bowel disease (1.4%). Possible reasons for the increased incidence of anal cancer in Crohn's disease mentioned were: an overall increase in malignancies in inflammatory bowel disease, the high incidence of perianal disease, and the chronic long-standing perianal inflammation present. All patients with Crohn's disease, especially if they have active perianal disease, should be observed for the occurrence of anal cancer.

Carcinoid tumour as a complication of ulcerative colitis

Patients with long-standing ulcerative colitis have an increased chance of developing a carcinoma of the colon, especially when the inflammatory process involves the entire colon, but no case of a carcinoid tumour of the colon occurring in a patient with ulcerative colitis has been reported.