Kinetics of changes in the crypts of the jejunal mucosa of dimethylhydrazine-treated rats

When symmetrical 1,2 dimethylhydrazine was administered to rats by weekly s.c. injection, 37% of the animals had developed small intestinal carcinomas after 21-27 weeks. These lesions were largely localized to duodenum and upper jejunum. At the same time there was a diffuse crypt hyperplasia in the jejunum which affected all the treated animals, not just those with neoplasms. This marked hyperplasia was preceded by a modest sustained crypt elongation which was seen soon after DMH injections began. In these hyperplastic jejunal crypts the absolute size of the proliferative compartment was increased, but the growth fraction calculated from labelling studies appeared to fall, probably by reduction in relative size of the proliferating population within the proliferative compartment. No convincing alteration in actual cell-cycle time was observed in the abnormal crypts. There was a slight (25%) increase in cell-production rate in the abnormal crypts.     

Cell proliferation of colonic neoplasms in dimethylhydrazine-treated rats.

We have measured mitotic indices and 3H-thymidine-labelling indices for the colonic epithelial tumours induced in rats by the administration of dimethyl-hydrazine (DMH). The fraction-of-labelled-mitoses (FLM) technique has been used to estimate the duration of the cell-cycle phases. In general, mitotic and labelling indices in the tumours are similar to those in the proliferation zone of the normal crypt epithelium; lesions considered to be least well differentiated on histological grounds appear to have the lowest mean labelling index. Benign tumours and the different types of malignant tumours have mean cell-cycle times about half those of the normal mucosa.     

Folate deficiency enhances the development of colonic neoplasia in dimethylhydrazine-treated rats.

In patients with ulcerative colitis, epidemiological work has suggested an association between low folate status and an increased risk of colonic neoplasia. The aim of the present study was to determine if experimental folate deficiency increases the likelihood of developing neoplasia in rats treated with the carcinogen dimethylhydrazine. Weanling male Sprague-Dawley rats were fed with an amino acid-defined diet containing either 8 or 0 mg/kg folic acid. After 5 weeks of defined diet, weekly s.c. injections of dimethylhydrazine (20 mg/kg) were administered to both groups. Serum, whole blood, liver, and colonic folate concentrations at the time of sacrifice were significantly lower in folate-depleted animals (P less than 0.001). There were significant differences in the incidence of colonic neoplasia between the two groups after 20 weeks of dimethylhydrazine exposure: folate-deficient rats had a greater incidence of dysplasia (6 of 7 versus 2 of 7 animals; P less than 0.05) and carcinoma (6 of 7 versus 1 of 7 animals; P less than 0.01). Furthermore, a significantly greater proportion of folate-replete rats than folate-deficient rats were free of neoplastic lesions (5 of 7 versus 0 of 7 animals; P less than 0.05). These results suggest that, in this animal model, folate deficiency increases the risk of malignancy when there is an underlying predisposition to colorectal cancer.     

Immunoglobulin-producing cells in the "transitional" mucosa adjacent to adenocarcinomas of the human large bowel.

Quantification of IgA-, IgM-and IgG-producing immunocytes was performed in a defined mucosal tissue unit adjacent to 16 adenocarcinomas of the large bowel, and compared with data for control units from 15 histologically normal specimens. The thickness of the “transitional” mucosa adjacent to the tumours was markedly increased. Thus, the average cancer-associated unit showed a 2.6-fold increase in height and its number of immunoglobulin-producing cells was raised 2.8 times. The numerical increase for IgA cells was 2.1, for IgM cells 5.1, and for IgG cells 13.0; the percentage proportions of these cell classes were changed from 91:6:3.6 to 71:12:17. Only very rare IgD-and IgE-producing cells were seen. The immunocyte density in 6-μm-thick sections (cell number/mm² of lamina propria) was 823, 136 and 201 for the IgA, IgM and IgG class, respectively, compared to the normal figures of 1,186, 73 and 49. The density of IgG and IgM cells was thus significantly increased and that of IgA cells decreased in the lamina propria of the “transitional” mucosa. The intra-individual scatter of all variables, including mucosal height, was large in the “transitional” mucosa, but the variables became normalized approximately 1 cm from the tumour. The excessive rise in the local production of IgG, with no concomitant increase in the density of IgA cells, indicates that there are local stimulatory factors bypassing the secretory IgA immune system. Further studies are needed to show if this local immune response reflects production of tumour-specific antibodies or is merely due to increased penetrability for antigens from the gut lumen passing through the tumour lesion.     

Mutations of p53 in morphologically non-neoplastic mucosa of long-standing ulcerative colitis.

Two cases of ulcerative colitis (UC)-associated carcinoma or dysplasia and morphologically non-neoplastic mucosa with p53 protein overexpression (MNNM-p53OE) were selected. DNA was extracted from the paraffin blocks of these lesions and exons 5 - 8 of the p53 gene were analyzed by PCR and direct sequencing. In addition, mutations in K-ras codon 12 were analyzed by PCR-RFLP methods. MNNM-p53OE was located surrounding and adjoining a coexisting carcinoma and / or dysplasia. A p53 mutation was detected in 12 / 22 (54.5%) MNNM-p53OE samples, 4 / 8 (50%) dysplasia samples and 8 / 8 (100%) carcinoma samples. The p53 mutations detected in MNNM-p53OE were identical to those demonstrated in the adjoining carcinoma and / or dysplasia. No K-ras codon 12 mutation was detected in any of the samples. These results indicate that MNNM-p53OE may share an identical clonal linkage with a coexisting carcinoma and / or dysplasia, and may be an initial and submorphological form of UC-associated neoplasia. Recognition of MNNM-p53OE in biopsy specimens may help to identify patients with UC at risk of developing colorectal carcinoma.     

Epithelial cell kinetics in the remaining colorectal mucosa after surgery for cancer of the large bowel

We used microautoradiography in order to evaluate cell replication of the remaining colorectal mucosa in 20 patients previously operated on for cancer of the large bowel. The results were compared to those of 24 controls without neoplasms or other relevant colorectal disease. Samples of colorectal mucosa were taken during endoscopy. At histological examination each labeled intestinal hemicrypt was divided into 5 longitudinal compartments, from the base to the surface, and S-phase cells in each compartment were counted. Total labeling index (LI, ratio of labeled to total cells x 100) and labeling index per crypt compartment were similar in surgical patients and in controls. In contrast, both total LI and labeling index in the upper portions of the crypt (compartments 3, 4, and 5) were significantly higher in the 9 patients who showed recurrence of polyps than in those (n = 11) without recurrence. The LI in compartments 4 and 5 (the "high crypt region") was 4.37 +/- 0.95 (SEM) in patients with recurrence versus 0.88 +/- 0.21 (P less than 0.001) in patients with negative endoscopy finding and 1.47 +/- 0.22 in controls. Moreover, the fifth compartment was labeled in 8 of 9 individuals in whom polyps recurred but in only 2 of 11 patients without recurrence and 3 of 24 controls. In conclusion, after resection for large bowel cancer colonic epithelial cell proliferation tends to become more quiescent and similar to that of controls. However, in the subgroup of patients in whom polyps reappear, the colorectal mucosa maintains a hyperproliferative state with an expansion of the replicative zone to the most superficial portions of the crypt. These findings support the sequence adenoma-carcinoma and suggest that the evaluation of cell proliferation might be useful in the identification of subjects at increased risk for multiple tumors of the large bowel.     

Leiomyosarcoma of the small and large bowel.

From 1950 through 1974, a total of 108 cases of primary intestinal leiomyosarcoma were seen at the Mayo Clinic. Most of these uncommon tumors occurred in the fifth and sixth decades of life, and more of them in men than in women (2.6:1). There were 73% in the small bowel, 25% in the large bowel, and 2% in the anus. Gastrointestinal bleeding and pain were the two most common signs at presentation, and they led to surgical exploration in all cases where they appeared. By the time surgery was performed, only 48% of the tumors could be resected with hope of cure. Within that group of cases, 50% of the patients survived 5 years, but only 35% survived 10 years, late recurrence being common. The histologic grade of the tumor affected survival to erroneous early optimism in prognosis.     

Modifying effects of a flavonoid morin on azoxymethane-induced large bowel tumorigenesis in rats.

The modifying effect of dietary exposure to a flavonoid morin during the initiation and post-initiation phases of azoxymethane (AOM)-initiated colorectal carcinogenesis was investigated in male F344 rats. A total of 55 animals were initiated with AOM by weekly s. c. injections of 15 mg/kg body wt for 3 weeks to induce colorectal neoplasms. Rats were fed a diet containing 500 p.p.m. morin for 5 ('initiation feeding') or 28 ('post-initiation feeding') weeks. Other groups contained rats treated with morin alone (500 p.p.m. in diet) and untreated rats. At the end of the study (32 weeks), the incidence of adenocarcinoma in the large intestine of rats initiated with AOM together with (43%) or followed by (29%) a diet containing morin was smaller than that of rats given AOM alone (75%). A significant difference was found between 'post-initiation feeding' and untreated groups (P = 0.023). Although both 'initiation feeding' and 'post-initiation feeding' of morin reduced polyamine levels in colorectal mucosa and blood, 'post-initiation feeding' of morin significantly decreased the proliferating cell nuclear antigen-positive index in aberrant crypt foci. 'Post-initiation feeding' of morin significantly elevated glutathione S-transferase and quinone reductase activities in the liver and large bowel, but 'initiation feeding' caused a significant elevation of these enzymes activities only in the large bowel. These results indicate that morin could exert a weak chemopreventive effect on large bowel tumorigenesis induced by AOM when fed during the post-initiation phase.     

Adenocarcinoma of the large bowel

Pathological features of 656 consecutive large bowel adenocarcinomas resected at the Middlesex Hospital in the 10-year period 1951-61 have been studied, comparing right and left colon and rectum.     

p53 mutations in the non-neoplastic mucosa of the human stomach showing intestinal metaplasia

In order to ascertain whether genetic alterations occur during the early stages of gastric carcinogenesis, abnormal accumulation of p53 protein and mutation of its gene in stomach tissue showing intestinal metaplasia were investigated using immunohistochemistry and polymerase chain reaction-single strand conformation polymorphism (PCR-SSCP) analysis. Immunohistochemistry detected 19 foci showing nuclear accumulation of p53 protein in non-neoplastic gastric mucosa in a total of 756 sections (477 of which contained intestinal metaplasia) from 16 resected stomachs containing gastric adenocarcinomas. Of these 19 p53-positive foci, 17 were diagnosed histologically as incomplete-type intestinal metaplasia and 2 as pseudopyloric glands in the regenerative mucosa. Furthermore, 14 such foci were detected in 6 patients with multiple gastric cancers. No correlation between high-iron diamine (HID)-positive sulfomucin production and p53-positive glands was observed. The DNAs were extracted selectively from these p53-positive metaplastic glands and examined for p53 mutations by PCR-SSCP analysis followed by direct sequencing. In only 10 lesions could exons 5 to 8 be investigated completely, and of these, 4 were shown to possess p53 mutations, which were on exon 5 in 3 cases and on exon 7 in 1 case. These results indicate that irreversible genetic changes had already occurred in morphologically non-neoplastic gastric mucosa with intestinal metaplasia, and are consistent with the hypothesis that intestinal metaplasia, especially the incomplete type, may contain precursor lesions of gastric cancer. © 1996 Wiley-Liss, Inc.     

Enhanced expression of glutathione S-transferases in colorectal carcinoma compared to non-neoplastic mucosa

Ten paired samples of primary human colorectal carcinoma and adjacent non-neoplastic mucosa were analysed for total glutathione S-transferase (GST) activities as determined by 1-chloro-2,4-dinitrobenzene assays. These tissues were also investigated for the expression of acidic (pi), basic (alpha) and neutral (mu) GSTs using Western blotting procedures and immunohistochemical staining. For each of the paired samples examined the total GST activity was higher in tumour than in adjacent non-neoplastic mucosa. Western blotting, using an antibody against acidic GST also showed strong immunoreactivity in all the samples with more intense reactions in tumour compared to mucosa in nine out of the ten paired samples. Low levels of basic GST were also expressed in all samples of tumour and mucosa. Neutral GST was not detectable in two samples of tumour and corresponding mucosa, but low levels of expression were demonstrated in the remaining eight. Immunohistochemical staining for acidic GST showed a dark brown reaction in all tumour cells; in non-neoplastic mucosa there was positive immunoreactivity for epithelial cells situated deep within the crypts and a negative reaction for surface epithelial cells. Immunohistochemical staining for basic GST was negative except for one sample of tumour and two of mucosa. Neutral GST was expressed only in two samples of tumour and two samples of mucosa. We therefore conclude that there is enhanced expression of GSTs, acidic GST being the predominant form, in tumour compared to normal mucosa, in keeping with a role for GSTs in colonic carcinogenesis and acquired or innate drug resistance.     

Prognosis of stage II colon cancer by non-neoplastic mucosa gene expression profiling

We have assessed the possibility to build a prognosis predictor (PP), based on non-neoplastic mucosa microarray gene expression measures, for stage II colon cancer patients. Non-neoplastic colonic mucosa mRNA samples from 24 patients (10 with a metachronous metastasis, 14 with no recurrence) were profiled using the Affymetrix HGU133A GeneChip. Patients were repeatedly and randomly divided into 1000 training sets (TSs) of size 16 and validation sets (VS) of size 8. For each TS/VS split, a 70-gene PP, identified on the TS by selecting the 70 most differentially expressed genes and applying diagonal linear discriminant analysis, was used to predict the prognoses of VS patients. Mean prognosis prediction performances of the 70-gene PP were 81.8% for accuracy, 73.0% for sensitivity and 87.1% for specificity. Informative genes suggested branching signal-transduction pathways with possible extensive networks between individual pathways. They also included genes coding for proteins involved in immune surveillance. In conclusion, our study suggests that one can build an accurate PP for stage II colon cancer patients, based on non-neoplastic mucosa microarray gene expression measures.     

Pattern of cell kinetics in colorectal mucosa of patients with different types of adenomatous polyps of the large bowel

It is generally accepted that adenomatous polyps represent the natural precursor of many colorectal malignancies. The sequence, however, which leads from a normally appearing mucosa to cancer is complex and involves many steps, including a hyperproliferative mucosa with an upward expansion of the replicative compartment. The current study evaluates cell replication in normal colorectal mucosa of patients with adenomatous polyps of various types and relates the observed findings to the main clinical and morphologic features of adenomas. Forty-four patients with polyps and 27 controls entered the study. Samples of colorectal mucosa were taken at endoscopy and cell replication was evaluated with a standard autoradiographic procedure. Cell replication was expressed as labeling index (LI), in the whole crypt and in each of the five longitudinal compartments in which the crypts were divided. Total LI and LI per crypt compartment were significantly higher (P less than 0.02 and P less than 0.01, respectively) than in controls. There was no appreciable difference of LI values between patients with single or multiple, tubular or tubulovillous, small or large adenomas, but in all of these subgroups LI was significantly higher than in controls. In conclusion, in normally appearing colorectal mucosa of patients with adenomatous polyps there was a significant increase of cell replication and a marked upward expansion of the proliferative zone; these changes were more evident in the left colon and in the rectum. Finally, cell replication did not seem to be related to the number of polyps, to the most common histotypes, or to the pattern of recurrence.     

Experimental studies on the pathogenesis of the chronic radiation ulcer of the large bowel in rats

Following local irradiation of a 24 mm segment of the large bowel with 23 Gy, 90% of Wistar rats developed a chronic radiation ulcer leading to progressive large bowel obstruction within 8 weeks. The incidence and latency of the chronic radiation damage was markedly altered by local treatments after irradiation, especially those which modified the amount and texture of the feces. The results of these studies suggest that the primary radiation damage to the large bowel is to the microvasculature of the mucosal and submucosal stroma leading to progressive mucosal atrophy which thus becomes very vulnerable. The chronic radiation ulcer and the hypertrophic, cystic mucosa (which is the result of hyperregeneration of subclinical ulcers) are secondary to the interaction of the primary radiation damage to the vascular-connective tissue of the intestinal wall with mechanical and infectious damage to the chronically atrophic mucosa.     

Glycoconjugate with Ulex europaeus agglutinin-I-binding sites in normal mucosa, adenoma, and carcinoma of the human large bowel

Cancerous lesions and nonneoplastic mucosa of surgically extirpated specimens from 94 patients with colorectal carcinoma (of the right colon, 31 patients; of the left colon, 29 patients; and of the rectum, 34 patients) and endoscopically polypectomized specimens from 18 patients with rectal adenoma were examined with fluorescein isothiocyanate-conjugated or horse-radish peroxidase-conjugated Ulex europaeus agglutinin-I (UEA-I) specific to a certain terminal alpha-L-fucosyl residue in glycoconjugates. Of the 31 patients with right colon cancers, 22 showed positive UEA-I binding in the neoplastic cell apexes, apical luminal borders, and luminal secretions. The adjacent nonneoplastic mucosa of all 31 patients, however, demonstrated positive UEA-I binding in the goblet cell mucus. UEA-I binding was positive for 23 of the 29 left colon cancers and for 28 of the 34 rectal cancers, although UEA-I binding was not revealed in the adjacent nonneoplastic mucosa for most of the cases. Of the 18 rectal adenomas, 12 specimens showed positive UEA-I binding in the apical secretions of their adenoma cells. Marked regional differences of UEA-I binding in the nonneoplastic mucosae indicated that the constituents of glycoprotein with UEA-I binding sites in goblet cell mucus differed significantly between the human right and left large bowels. Positive UEA-I binding in many rectal cancerous and adenomatous lesions suggested that a neoplastic glycoprotein with alpha-L-fucosyl residue was produced or that the terminal carbohydrate structure of glycoprotein present in the nonneoplastic mucosa was altered to bind easily with UEA-I after the neoplastic transformation had occurred. A possible relation of this UEA-I binding to blood group H(O) substance is discussed.     

Adenomatous lesions of the large bowel: an autopsy survey.

A comprehensive autopsy survey of the large bowel showed that adenomas were very common lesions occurring in about one-half of the 518 cases studied. The great majority were small adenomatous polyps (tubular adenomas), 86.7% measuring less than 10 mm in diameter. Adenomas with a more complex tubulovillous pattern were larger with a mean diameter of 19.0 mm. There was no apparent incresae in mean size of adenomas with age. Nineteen clinically unsuspected cancers were discovered. Fourteen (8 in situ and 6 invasive) cancers had areas of residual benign adenoma. Five invasive cancers had no residual benign component. No in situ carcinomas or small (less than 10 mm) invasive cancers not containing residual adenoma were found. The results suggest that, although adenomas of the large bowel are very common, the vast majority are simple adenomatous polyps which do not undergo progressive growth and malignant change. Conversely, it appears that cancers may arise from benign adenomas which have the characteristics of large size and a more complex villous architecture.