Altered distribution of beta-catenin, and its binding proteins E-cadherin and APC, in ulcerative colitis-related colorectal cancers.

The beta-catenin pathway plays a central role in transcriptional signaling and cell-cell interactions in colonic epithelium. Alterations of the expression of beta-catenin, and its binding partners E-cadherin and the adenomatous polyposis coli protein (APC), are frequent events in sporadic colorectal cancer. Ulcerative colitis (UC)-related cancers originate in a field of chronic inflammation and therefore may have different alterations in the beta-catenin pathway than sporadic cancers. To test this hypothesis, expression and subcellular localization of beta-catenin, E-cadherin, and APC were detected by immunohistochemistry in paraffin sections from 33 UC-related and 42 sporadic colorectal cancers. Although beta-catenin and E-cadherin expression were predominantly limited to the lateral cell membrane in normal colonic epithelium, both tumor groups showed an overall shift from membranous to cytoplasmic expression for these proteins. An increase in nuclear localization of beta-catenin and a decrease in cytoplasmic APC expression also were seen in both cancer groups compared with normal epithelium. Abnormal beta-catenin expression was more closely linked to E-cadherin alterations in UC-related cancers than in sporadic cancers. In contrast, abnormal beta-catenin expression was more closely linked to APC alterations in sporadic cancers than in UC-related cancers. These data suggest that alterations of the beta-catenin pathway are important in both UC-related and sporadic colorectal cancers. However, differences in the expression patterns of beta-catenin, E-cadherin, and APC between UC-related and sporadic colorectal cancers suggest that the specific alterations in this pathway may differ in these two cancer groups.

Chromosomal alterations in ulcerative colitis-related and sporadic colorectal cancers by comparative genomic hybridization.

Both ulcerative colitis (UC)-related and sporadic colorectal cancers are thought to evolve through a multistep process of genomic instability, accumulation of genomic alterations, and clonal expansion. This process may involve different genomic changes in UC-related cancers than in sporadic cancers because of the origin of UC-related cancers in an inflammatory field. This study was designed to define the specific genomic events occurring in UC-related cancers. Comparative genomic hybridization (CGH) was performed on 32 UC-related and 42 stage-matched sporadic colorectal cancers. The mean number of chromosomal alterations per case was similar in the UC-related and sporadic tumor groups (8.6 in UC, 8.1 in sporadic). The 2 tumor groups shared many chromosomal alterations: losses on 18q (78% UC v69% sporadic), 8p (53% v50%), 17p (44% v57%), and gains on 8q (63% v45%), 20q (44% UC v67%), and 13q (44% UC v38%). However, differences in the frequency and timing of specific alterations were observed. Chromosome 5q was lost in 56% of UC-related but in only 26% of sporadic cancers. Alterations of chromosome 8 were associated with stage progression in UC-related, but not in sporadic cancers. In contrast, 18q loss was associated with stage progression in sporadic cancers only. Thus, differences in the frequency and timing of individual chromosomal alterations suggest that genetic progression in these 2 tumor groups may follow multiple pathways.

Genomic instability is an early event during the progression pathway of ulcerative-colitis-related neoplasia.

Ulcerative colitis (UC) is a chronic inflammatory disease of the colon associated with a high risk of colorectal cancer. This increased cancer risk is thought to result from the cellular damage induced by the inflammatory field. The aim of this study was to determine the pattern and time course of genomic instability occurring in UC-related neoplasia. Sites of cancer, dysplasia, and nondysplasia from 14 UC colectomy cases containing cancer were analyzed for chromosomal alterations by comparative genomic hybridization (CGH) and for microsatellite instability using a series of 10 microsatellite markers. Clonal chromosomal alterations were present in 85% of cancer sites, 86% of dysplasia sites, and 36% of nondysplasia sites. Losses of chromosome 18 or 18q and chromosome 5 or 5q were common in cancer and dysplasia and were occasionally detected in nondysplasia. High-level microsatellite instability was detected in the cancer and dysplasia of two cases. Samples that demonstrated high-level microsatellite instability were unlikely to have chromosomal alterations demonstrable by CGH. These studies suggest that the predominant type of genomic instability in UC-related neoplasia is associated with chromosomal alterations and that this type of genomic instability frequently occurs before the development of histologically defined dysplasia.

Rapid development of severe copper deficiency in a patient with Crohn's disease receiving parenteral nutrition.

A 32-year-old man with active Crohn's disease and recurrent small bowel strictures underwent abdominal surgery and was subsequently given total parenteral nutrition (TPN). Severe cholestasis developed and copper was removed from the TPN. Although serum ceruloplasmin levels were within normal limits, 8 weeks after copper removal, he developed pancytopenia. Serum copper levels were severely depressed. Bone marrow biopsy was consistent with copper deficiency; cytoplasmic vacuolization of both myeloid and erythroid precursors, megaloblastic erthropoiesis, and marked hypocellularity were observed. IV replacement with copper sulfate resulted in improvement in the patient's anemia, neutropenia, and thrombocytopenia, but the patient died suddenly from cardiac tamponade. Postmortem examination revealed fibrinous and hemorrhagic pericarditis. Despite the rare occurrence of overt copper deficiency, this case emphasizes the need to recognize copper deficiency as an important etiology of iron-resistant anemia in patients receiving TPN. Furthermore, the relative rapidity with which our patient developed pancytopenia suggests that, in view of the established recommendation that copper be removed from TPN in cholestatic conditions, serum copper levels must be measured periodically.

Chromosomal alterations in ulcerative colitis-related neoplastic progression.

BACKGROUND & AIMS: It is unclear whether genomic derangement precedes the histological development of dysplasia in ulcerative colitis (UC)-related neoplastic progression. The primary aim of this study was to determine if chromosomal alterations occur early in the progression pathway of UC-related neoplasia. METHODS: Fluorescence in situ hybridization (FISH) was performed on nuclei dissociated from sites of cancer, dysplasia, and UC-involved nondysplastic epithelium in five UC-related cancer colectomy specimens using a panel of pericentromeric probes. Comparative genomic hybridization (CGH) was used to detect clonal chromosomal losses and gains in DNA extracted from these sites. RESULTS: FISH analysis revealed significant and often dramatic alterations in chromosome copy number compared with controls in all biopsy specimens of cancer, dysplasia, and nondysplastic UC-involved epithelium. Clonal chromosomal losses and gains were detected by CGH in all but one analyzed site of dysplasia and cancer and in two of the five nondysplastic sites. FISH and CGH frequently detected the relative loss of chromosome 18. CONCLUSIONS: Chromosomal alterations may occur early in UC-related neoplastic progression and seem to precede the histological development of dysplasia. Relative loss of 18q may be important in the progression of UC-related neoplasia. The detection of chromosomal alterations as an intermediate end point may prove useful in identifying patients at high risk for the development of colorectal cancer.

Inflammatory bowel disease.

Patients with extensive ulcerative and Crohn's colitis represent a group at high risk for developing colorectal cancer. Two clear independent risk factors for developing colorectal cancer in patients with chronic colitis include duration and extent of disease. Cancers in chronic colitis do not develop from a colonoscopically recognizable adenomatous polyp similar to that in sporadic colon cancer, but instead arises from flat dysplastic epithelium that is typically not colonoscopically distinguishable from adjacent nondysplastic epithelium. All patients with extensive disease require active management of their increased cancer risk. Active management of cancer risk in chronic long-term colitis should not be presumed to be equivalent to colonoscopic surveillance. There is little data with which to reassure a patient regarding the efficacy of colonoscopic surveillance. A reasonable alternative to colonoscopic surveillance in patients with ulcerative colitis is the restorative proctocolectomy (ileoanal pull-through), which maintains continence and avoids a stoma and appliance. If colonoscopic surveillance is undertaken, a clear understanding of what the definition of a positive surveillance test, ie, when surgical action is taken, is pivotal to the success of the surveillance program. There are now ample data confirming that the finding of any unequivocal dysplasia (low- or high-grade) is associated with a high risk of coexistent or future colorectal cancer. Dysplasia confirmed by a second pathologist (preferably an experienced gastrointestinal pathologist) should prompt a recommendation for colectomy. Future cancer surveillance in chronic colitis will almost certainly involve some applied molecular genetic test.

Postnatal changes in receptor-mediated rabbit gastric smooth muscle relaxation.

The aims of this study were to identify mediators of relaxation in rabbit proximal gastric circular smooth muscle and to assess age-dependent changes in tissue response. Vasoactive intestinal peptide (VIP), adenosine, and norepinephrine induced tetrodotoxin-insensitive, concentration-dependent relaxation in bethanechol-precontracted (3 microM) gastric muscle strips from newborns and weanlings. Maximally effective concentrations of 10 microM VIP induced complete relaxation in newborns, but only 30% relaxation in weanlings (p < 0.01). Maximally effective concentrations of adenosine induced complete relaxation at both ages. Adenosine (ED50 3 microM) was more potent than adenosine triphosphate, indicating the presence of P1 purinergic receptors. In newborns norepinephrine induced complete relaxation (ED50 0.5 microM). The response to norepinephrine changed in age-dependent increments from relaxation in newborns to strong contraction in weanlings. In weanlings phentolamine inhibited norepinephrine-stimulated contraction, revealing persistent propranolol-sensitive relaxation. Tetrodotoxin and atropine had no effect on norepinephrine-stimulated contraction. In summary, in rabbit gastric circular smooth muscle: (1) VIP, adenosine, and norepinephrine induce relaxation; (2) VIP loses efficacy with age; (3) there is a beta-adrenergic receptor mediating relaxation in the newborn which persists, and (4) an alpha-adrenergic receptor mediating contraction emerges early in postnatal life. Age-dependent changes in response to VIP and norepinephrine may contribute to the postnatal maturation of the gastric motility.

Mechanisms of cAMP-mediated relaxation of distal circular muscle in rabbit colon.

Photolytic release of free adenosine 3',5'-cyclic monophosphate (cAMP) from its caged form was used to evaluate the physiological role of several proposed mechanisms of cAMP-mediated relaxation of circular smooth muscle in the distal rabbit colon. Photolysis of caged cAMP produced a rapid relaxation of bethanechol-contracted distal circular muscle strips that was dependent on ultraviolet exposure time. An increase in release of free cAMP, associated with increased ultraviolet exposure, was confirmed with high-performance liquid chromatography. Vanadate (an ATPase inhibitor) (3 mM) caused a 48% decrease in cAMP-mediated relaxation, while ouabain and a zero K+ bath solution failed to affect relaxation. cAMP-mediated relaxation of KCl-contracted strips was significantly less effective than that of bethanechol-contracted strips. Although this finding suggested that cAMP-mediated relaxation may involve K+ channel modulation, specific (glibenclamide, charybdotoxin) and nonspecific (TEA) K+ channel blockade failed to affect cAMP-mediated relaxation of bethanechol-contracted strips. The photolytic release of cAMP failed to relax Ca(2+)-contracted saponin skinned muscle strips. These studies suggest 1) modulation of Ca2+ pumps plays an important role in this model of relaxation of distal colonic circular muscle in the rabbit colon, 2) modulation of the Na+ pump or sarcolemmal K+ channels may not play an important physiological role in relaxation induced by a rapid rise in intracellular cAMP, and 3) cAMP does not seem to have a significant physiological effect on the Ca2+ sensitivity contractile apparatus.

Differences in the response of proximal and distal rabbit colonic muscle after electrical field stimulation.

Electrical field stimulation (EFS) was performed on rabbit proximal and distal circular colonic smooth muscle to study the mechanisms of neural control of the colon. Electrical pulses were applied with parallel silver plate electrodes to muscle that had been stretched to Lo. The proximal muscle demonstrated an on-contraction during EFS. In distal muscle, EFS initiated an on-relaxation, followed by an on-contraction and an off-contraction. The time delay for the on-contraction of distal muscle was longer by 2.5 +/- 0.5 s than was the delay in proximal muscle (p less than 0.02). The amplitudes of the on- and off-contraction were dependent on the frequency of the EFS. The on- and off-responses were completely inhibited by 3 x 10(-6) M tetrodotoxin. Atropine inhibited the distal on-contraction at all EFS frequencies and the proximal on-response at EFS frequencies less than 16 Hz. Atropine had a partial inhibitory effect on the distal off-response (approximately 30%). Bombesin and substance P were released during prolonged EFS. Desensitization of the distal colonic muscle to bombesin did not affect the distal off-contraction. However, desensitization of the tissue to substance P and exposure to substance P antagonists inhibited the distal off-contraction. These studies suggest that (a) acetylcholine mediates the on-contraction of the distal circular colonic muscle, and a major part of the on-contraction for the proximal muscle, and (b) substance P is responsible for the off-contraction of the distal muscle.