Differential activation of ornithine decarboxylase and tyrosine kinase in the rectal mucosa of patients with hyperplastic and adenomatous polyps

Arginase activity in carcinoma of the gallbladder: a pilot study

Carcinoma of the gallbladder is the third most common cancer of the gastrointestinal tract. Recent studies have shown increased arginase activity in various malignancies. The main aim of this study was to evaluate whether arginase activity increases in carcinoma of the gallbladder. The arginase activity was evaluated in serum and gallbladder tissue in 22 patients with histologically proven carcinoma of the gallbladder and 20 patients with cholecystitis using spectrophotometry and western blot assay. The Student's t-test, analysis of variance, and Student-Newman-Keuls test were used for comparison of data and for statistical significance. The mean tissue arginase and serum arginase activity (118.64+/-17.45 and 15.91+/-1.91, respectively) in cases of carcinoma of the gallbladder were significantly higher in comparison with cholecystitis (86.37+/-4.45 and 12.73+/-0.72, respectively). Subgroup analysis showed stage III gallbladder carcinoma had the maximum tissue arginase activity (142.00+/-21.68 U/g of tissue) followed by stage II (124.15+/-19.88) and stage I (108.46+/-6.73). This significant rise in mean tissue arginase and serum arginase activity in patients with gallbladder cancer probably supports an association between arginase activity and the malignancy.

Trophic effects of glicentin on rat small-intestinal mucosa in vivo and in vitro

To define the role of glicentin the active site of enteroglucagon, we evaluated the trophic effects of recombinant rat glicentin on rat small intestine and IEC-6 cells. In vivo, a significant increase was observed in jejunal wet weight, protein content, DNA content, and alkaline phosphatase activity after the subcutaneous administration of 100 micrograms/kg per day of glicentin for 2 weeks. In the ileum, however, there were no significant differences between the control versus glicentin groups in any of these parameters. Ornithine decarboxylase (ODC) activity 3.5 h after an intraperitoneal injection of glicentin was increased in the jejunal mucosa, but not in the ileal mucosa. In vitro, glicentin, at a dose of more than 100 ng/ml, significantly increased both tritium-thymidine incorporation and the number of IEC-6 cells. These findings indicate that glicentin exerts direct trophic effects on the rat small-intestinal mucosa and on the rat small-intestinal cell line, IEC-6, and that this peptide appears to be an active site of enteroglucagon.

Biochemical tests in diseases of the intestinal tract: their contributions to diagnosis, management, and understanding the pathophysiology of specific disease states

Biochemical testing plays a major role in the complete evaluation of patients with suspected or established intestinal disease. We have classified these tests according to the medium in which they are performed: breath tests, including isotopic and nonisotopic tests, fecal tests, urine tests, serum tests, tissue tests, and other tests. The principles of various tests are outlined, and the role of each test in the evaluation of particular gastrointestinal disorders is discussed.

Arginase activity determination. A marker of large bowel mucosa proliferation

Arginase activity of the intestinal mucosa was tested as a proliferative marker in the adenoma-carcinoma sequence. The enzyme activity was determined by an end-point colorimetric method with L-arginine as substrate. Arginase activity was evaluated in 430 biopsy samples of large bowel mucosa, polyps and cancer tissue. The activities (U/g protein, mean +/- SE; n) were: normal mucosa 83.2 +/- 7.3; 25, adenomas 199.4 +/- 19.1; 40, carcinomas 1269.7 +/- 174.9; 40, inflammatory bowel disease 1210.7 +/- 247.1; 34. The arginase activity differs significantly in the adenoma-carcinoma sequence according to the Duncan's test (p < 0.05).

Altered polyamine biosynthesis with aging after massive proximal small bowel resection in rat

We examined the effect of aging on polyamine biosynthesis in the small intestine. Two groups of male Wistar rats (young; 10-week-old, n = 40; old; 24-month-old, n = 40) underwent either a jejunal transection and reanastomosis or 90% proximal small bowel resection. The rats were sacrificed on the 1st, 2nd, 4th, and 7th postoperative day (POD). The mucosa was submitted for histological examination, weighed, and assayed for protein, DNA, RNA, and polyamine content. Ornithine decarboxylase (ODC) activity was measured and ODC mRNA in the mucosa was determined by Northern blot analysis. Compared with the values for wet weight and protein content in old rats, young rats showed significantly higher values for wet weight on the 1st and 2nd POD, and for protein content on the 1st POD, but there were no differences between young and old rats after the 4th POD. The values for ODC activity and ODC mRNA were significantly lower in old rats than in young rats on the 1st POD, but there were no differences between young and old rats after the 2nd POD. The value for putrescine in old rats was significantly lower on the 2nd POD, but was significantly higher on the 4th POD than that in young rats. The present study showed that, in old rats, the residual intestine after small bowel resection preserved sufficient adaptive capacity, but that the adaptive response was decreased. The findings in this study also suggest that a decrease in ODC mRNA expression is involved in the decreased adaptive response that occurs with aging.

Abnormal cell proliferation and p52/p35-CSK expression in the colons of aging rats

In rodents and in humans, aging is associated with increased gastrointestinal epithelial cell proliferation and an expanded crypt proliferative compartment similar to that seen in the preneoplastic bowel. We have compared the distribution of a series of cytoskeletal antigens that are modified when colonic cancer cells differentiate in vitro in the colon of young (4-7 month) and aging (22-26 month) Fischer 344 rats. Two such proteins, p52 and p35, (that are increased in cultured senescent cells) differ in their position in the crypt axis and subcellular localization between young and aging rats. In young rats, immunoreactive p52 protein is present solely near the colonic crypt surface epithelium but in aging rats p52 expressing cells are found deeper in crypts. The intracellular localization of p35 also differs markedly in young and aging animals. The distribution of these proteins appears to be a reproducible biomarker of aging. Antigenic changes similar to those observed in aging colons also are seen in crypt cells of patients with ulcerative colitis and in the flat colonic mucosa of patients with adenomatous polyps and colon cancer. The combination of proliferative and differentiation changes suggest that the flat mucosa of the colon of aging rats has preneoplastic features.

Ornithine decarboxylase as a marker for premalignancy in the stomach

Assessment of mucosal ornithine decarboxylase (ODC) activity in the human large bowel may be of value as a marker of potential malignant risk. Its value as a marker of premalignancy in the upper gastrointestinal tract is less clear. Using a [14C]-ornithine bioassay, gastric mucosal ODC activity was measured in 32 normal subjects and 22 patients with confirmed gastric cancer. These results were compared with 47 patients at increased risk of upper gastrointestinal malignancy, (32 patients with partial gastric resection, 15 patients with familial adenomatous polyposis). Median ODC activity in normal subjects was 371 pmol/mg protein/h, (interquartile range (IQR), 230-617). There was no variation with age or sex and no relation to Helicobacter pylori status. Normal subjects had significantly lower ODC activity than patients with a gastric resection or confirmed gastric cancer, but similar to patients with familial adenomatous polyposis. Furthermore, no difference in activity was identified between patients with a gastric resection and established gastric cancer. ODC activity was, however, significantly increased in areas of gastric atrophy or intestinal metaplasia, regardless of the clinical group from which the samples were obtained. It is concluded that measurement of mucosal ODC activity does not provide additional predictive information of malignant risk in the stomach and investigation of other potential biomarkers of malignancy is warranted.

Identification and evaluation of the role of endogenous tyrosine kinases in azoxymethane induction of proliferative processes in the colonic mucosa of rats

Although tyrosine kinases (Tyr-k) are known to play a role in regulating proliferation of normal, preneoplastic and neoplastic cells, little is known about the identity of different species of Tyr-k involved in this process. Utilizing a non-denaturing polyacrylamide gel electrophoresis system, in which the separated proteins from tissue extracts are assayed directly for Tyr-k, we attempted to identify the species of Tyr-k that may be involved in azoxymethane (AOM) induction of colonic mucosal ornithine decarboxylase (ODC) activity, an enzyme whose activity is known to rise in rapidly proliferating cells. We have observed that 5 days after a single injection of the colonic carcinogen AOM (20 mg/kg body wt) to 3-4-month old rats, a significant 230% rise in colonic mucosal proliferative activity (as evidenced by 5-bromo-2'-deoxyuridine (BrdU) immunoreactivity) was also accompanied by a 550% increase in ODC activity. This was also associated with a marked rise (140-240%) in the relative activity of Tyr-k of three mucosal proteins with MI of 165, 145 and 125 kDa. Since the molecular mass of one of the Tyr-k (165 kDa) corresponded to that of EGF-receptor (EGF-R), this led us to examine the role of EGF-R Tyr-k in AOM induction of colonic mucosal ODC. We observed that a 320% increase in mucosal ODC activity, 5 days after AOM injection, was accompanied by over 200% rise in Tyr-k activity of EGF-R. Daily injection of tyrphostin (300 micrograms/kg body wt.), a Tyr-k inhibitor with a higher specificity for EGF-R Tyr-k, significantly attenuated AOM-induced stimulation of both ODC and Tyr-k activity of EGF-R. Administration of AOM also stimulated the rate of synthesis and secretion of TGF-alpha in isolated colonocytes. In addition, the levels of TGF-alpha and its mRNA in the colonic mucosa were also found to be 100% and 250% higher, respectively, in AOM-treated rats when compared with the controls. We suggest that (a) activation of intrinsic Tyr-k of EGF-R is an important event in AOM induction of colonic mucosal proliferative processes, and (b) this activation is thought to be mediated by TGF-alpha through an autocrine mechanism.

Variable activity of protein tyrosine kinase in apparently normal thyroid glands

We examined protein tyrosine kinase (PTK) activity in apparently normal thyroid tissue (n = 22) obtained from patients undergoing thyroid surgery for papillary thyroid cancer or benign disease. The PTK activity in apparently normal thyroid tissue from patients with papillary thyroid cancer progressively was elevated in the cytosolic fraction compared with that from patients without cancer (p < 0.05). The cytosolic proportion of PTK activity was also significantly increased in the normal thyroid tissue of patients with cancer (62% vs. 51%, p < 0.05). These findings suggest that alterations in PTK activity may indicate apparently normal thyroid tissue at increased risk of developing malignancy.

Failure of rectal ornithine decarboxylase to identify adenomatous polyp status

Rectal mucosal ornithine decarboxylase (ODC) activity has been reported to distinguish between patients with and without adenomatous polyps (AP). In the present investigation, ODC activity has been measured in 28 patients with AP and 34 patients without AP. To assess the intraindividual variation in ODC activity, repeat biopsies were performed on 11 patients. In addition, the effect of postbiopsy sample handling was investigated by storage of samples on either dry or wet ice during transport to the laboratory. The mean rectal mucosal ODC activity in patients with AP was 196.0 +/- 195.5, whereas that in AP negative patients was 182.2 +/- 320.5. The rectal mucosal ODC activity in patients with colorectal cancer was 388.2 +/- 581. Repeat samples in individuals were generally within the same range as the original samples. The method of sample transport did not significantly affect the level of ODC measured in a particular biopsy. Because of high variability in rectal mucosal ODC activity within the population, there was wide overlap in ODC values between those patients with and without AP in an unselected general population. Thus, the measurement of flat rectal mucosal ODC activity is not a good predictor of the presence or absence of AP. Additional studies of the factors affecting mucosal ODC activity are necessary before the potential clinical utility of the method can be realized in the general population.