Differential diagnosis of chronic pancreatitis and pancreatic cancer in brush cytology specimens

Discrimination between chronic pancreatitis and pancreatic carcinoma can be complicated, particularly in brush cytology specimens. Previous studies have shown that the oxygen insensitivity of the histochemical reaction to detect glucose-6-phosphate dehydrogenase activity based on neotetrazolium reduction can be used for discriminating malignant cells from nonmalignant cells. In the present study, we investigated the value of the assay for differential diagnosis between the two pancreatic diseases. Oxygen insensitivity in ductal epithelial cells in normal human pancreas, chronic pancreatitis, and pancreatic carcinoma was determined by quantitative image analysis in sections of biopsies and in brush cytology preparations. In sections, the reaction in the absence of oxygen was a proper reflection of glucose-6-phosphate dehydrogenase activity, whereas in the presence of oxygen only malignant cells showed a significant reaction. Of 39 brush cytology specimens, diagnosis of all 11 cases of pancreatitis and 28 cases of cancer with the oxygen insensitivity test were in agreement with independent measures of chronic pancreatitis and cancer. The oxygen insensitivity test is a simple and valuable tool in addition to conventional pathology for differential diagnosis between pancreatitis and pancreatic cancer, both in biopsies and in brush cytology specimens.     

High c-myc protein expression in benign colorectal lesions correlates with the degree of dysplasia.

Sections of normal colon (n = 14), hyperplastic polyps (n = 31) ulcerative colitis (n = 97) and tubular adenomas (n = 40) were examined by immunohistochemistry for the expression of the c-myc proto-oncogene product in order to assess its potential diagnostic value in predicting the malignant potential of these lesions. We compared the degree of epithelial abnormality in these colorectal specimens with the extent of immunoperoxidase staining for c-myc oncoprotein, we found that high c-myc protein expression correlated with the degree of epithelial alteration in ulcerative colitis and tubular adenoma groups. Weakly positive staining was found in 10 out of 14 normal colon samples and 28 out of 31 hyperplastic polyps. High tissue expression of c-myc protein, when combined with histologic dysplasia, may prove to be an additional factor in the evaluation of malignant potential in ulcerative colitis specimens and adenomas.     

Activation of c-Ki-ras in human gastrointestinal dysplasias determined by direct sequencing of polymerase chain reaction products

Activation of c-Ki-ras by point mutation within exon 1 was studied in 33 specimens of dysplastic gastrointestinal lesions or of cancers presumed to arise from dysplasia. Samples were obtained from patients with underlying ulcerative colitis or Barrett's esophagus, two diseases associated with dysplasia and increased rates of colonic or esophageal adenocarcinoma, respectively. Genomic DNA was amplified using primers bounding this exon in the polymerase chain reaction. Polymerase chain reaction products were analyzed by direct dideoxy sequencing. Three point mutations in codon 13 of c-Ki-ras were found, all in colonic specimens (two high-grade dysplasias and one adenocarcinoma arising in ulcerative colitis). No point mutations were observed in the second exon of c-Ki-ras or in and around codons 12, 13, and 61 of c-N-ras and C-Ha-ras in a partial sampling of the specimens. These data indicate that ras family protooncogene activation is an uncommon event at this level of malignant progression in these disease states. Carcinogenesis in ulcerative colitis and Barrett's esophagus may proceed via different pathways than in sporadic colon cancer, perhaps involving loss or inactivation of suppressor genes.     

Histochemical characterization of focal hepatic lesions induced by single diethylnitrosamine treatment in infant mice

Focal hepatocellular lesions, induced in our infant mouse system (15-day-old B6C3F1 mice) by a single carcinogenic dose of diethylnitrosamine (2.5 or 5.0 micrograms/g body weight), were characterized histochemically using toluidine blue, periodic acid-Schiff, glycogen phosphorylase, glycogen synthetase, glucose-6-phosphatase, glucose-6-phosphate dehydrogenase, glyceraldehyde-3-phosphate dehydrogenase, ATPase, gamma-glutamyl transpeptidase, and acid phosphatase. Animals were killed 5, 12, 18, and 24 weeks following diethylnitrosamine treatment. The first focal lesions were observed in mice killed at 12 weeks. All foci showed patchy cytoplasmic basophilia and a slight decrease in the glycogen content. The early foci (12 weeks) showed no change in the levels of glycogen phosphorylase and glycogen synthetase, a strong reduction of glucose-6-phosphatase, and a high increase in glucose-6-phosphate dehydrogenase. In addition, 56% of foci in males and 86% of foci in females showed a slight rise in glyceraldehyde-3-phosphate dehydrogenase, and 12% of foci in males and 17% of foci in females had a lower acid phosphatase. The level of cytoplasmic ATPase was slightly decreased in 22% of foci. By 24 weeks, a decrease in the activity of cytoplasmic ATPase was observed in 84 and 100% of foci in males and females, respectively. The increase in the membrane ATPase was observed in 65% of foci in males and 7% of foci in females. By that time, the decrease in acid phosphatase was observed in 78% of foci in males and 37% of foci in females. The gamma-glutamyl transpeptidase failed to show any increase in its activity, indicating that this enzyme was not a "marker" of the hepatocellular lesions developing under the experimental conditions. Strong decrease in glucose-6-phosphatase in association with a manifest increase in glucose-6-phosphate dehydrogenase and glyceraldehyde-3-phosphate dehydrogenase activities indicated a shift from gluconeogenesis to glycolysis. Since this metabolic shift occurred concurrently with an increase in the labeling indices and focal size, it appears that these changes act in concert, representing expression of the acquired functional and replicating potential of the focal cell population.     

Evaluation of a test for abnormal rectal mucus for early detection of colon cancer.

This report describes the evaluation of a chemical test for T-antigen in rectal mucus as a screening test for colon cancer. The test, called the Mucus Strip Test, detects the disaccharide residue sialic acid-free beta-D-Gal(1-->3)-D-GalNAc or T-antigen, which accumulates in mucus from malignant cells and colonic mucosa adjacent to cancer but not in normal mucosa. Participants were an unselected case series of 660 persons undergoing colonoscopy, excluding those with ulcerative colitis, polyposis, Crohn's disease, or nonspecific inflammatory bowel disease. In the first study (n = 608) rectal mucus was collected after preparation of the bowel for colonoscopy; in the second study (n = 52) a modified protocol was used to collect mucus approximately 2 weeks before colonoscopy and again following preparation for the procedure. Mucus Strip Test results were compared to the diagnosis received after colonoscopy, which was classified as cancer, adenomatous polyp(s), and others (normal). Analyses were also stratified by previous history of large intestinal disease, classified as previous cancer; previous diagnosis of adenomatous polyp(s); or others. In the first study, T-antigen was detected in approximately 30% of mucus samples, and test results were independent of both diagnosis at colonoscopy and previous medical history. In the second study, T-antigen was detected in 85% of samples collected before and 96% of samples collected after preparation for colonoscopy, but test results were again independent of diagnosis and medical history.(ABSTRACT TRUNCATED AT 250 WORDS)     

Potential role of lipid peroxidation derived DNA damage in human colon carcinogenesis: studies on exocyclic base adducts as stable oxidative stress markers

Molecular pathways to colorectal cancer involve multiple genetic changes that may be caused by overproduction of reactive oxygen species in cancer-related genes. Our aim was to investigate, whether besides direct oxidative DNA damage, reactive oxygen and nitrogen species induce lipid peroxidation (LPO) that could yield etheno-DNA adducts via trans-4-hydroxy-2-nonenal, a major aldehyde generated by LPO, in colon tissue. We analyzed the etheno-DNA adducts by a highly specific, ultrasensitive method involving immunoaffinity chromatography coupled with 32P-postlabelling [Carcinogenesis 16 (1995) 613] in affected colon epithelium from ulcerative colitis, Crohn's disease and familial adenomatous polyposis (FAP) and compared them with asymptomatic colon tissue. In all these cancer prone colon tissues, the formation of markedly enhanced etheno adduct levels was demonstrated for the first time. Etheno-DNA adducts are promutagenic and cause genomic instability that could drive the inflamed colonic epithelia to malignancy. Etheno-DNA adducts appear promising biomarkers for (i) quantifying increased DNA damage in early stages of colon carcinogenesis and for (ii) verifying the efficacy of new antioxidants (e.g. [Lancet Oncol. 1 (2000) 107]) and chemopreventive agents in lowering oxidative stress and related cancer risk.     

Correlative histochemistry of some enzymes of carbohydrate metabolism in preneoplastic and neoplastic lesions in the rat liver

The livers from a total of 51 Sprague-Dawley rats treated withdifferent doses of N-nitrosomorpholine (80–120 mg/l inthe drinking water) for up to 14 weeks together with the liversof 28 control animals were histochemically investigated at thecessation of carcinogenic insult and at varying periods thereafterfor their glycogen content, basophilia and activities of variousenzymes of carbohydrate metabolism: glycogen synthetase, glycogenphosphorylase, glucose-6-phosphatase, glyceraldehyde-3-phosphatedehydrogenase and glucose-6-phosphate dehydrogenase. The enzymaticpatterns of normal tissue, preneoplastic and neoplastic lesionswere characterized and compared with reference to the morphologicallydefined stages of tumor development in the liver. The earlyappearing glycogen storing areas, localized in the peripheraland intermediate lobular regions, did not show significant changesin the histochemically demonstrable activities of the enzymestested. After cessation of the carcinogen treatment the morepronounced glycogen storage foci which developed within theaforementioned regions of the liver acinus usually showed areduction in the activities of phosphorylase and glcose-6-phosphatasewhile the activity of glucose-6-phosphate dehydrogenase, a keyenzyme for the pentose phosphate pathway, was increased. Themixed cell foci, neoplastic nodules and tumors which emergedat later stages were characterized by a progressive shift awayfrom glycogen metabolism towards glycolysis and the pentosephosphate pathway, as indicated by an increase in glyceraldehyde-3-phosphatedehydrogenase and glucose-6-phosphate dehydrogenase activities.These changes in enzyme pattern are supportive of a developmentalsequence leading from glycogen storage foci through mixed cellfoci and neoplastic nodules to hepatocellular carcinomas.     

Prolonged chronic inflammation progresses to dysplasia in a novel rat model of colitis-associated colon cancer

Inflammatory bowel disease (IBD) is a gastrointestinal disorder of unknown etiology or cure. One complication of IBD is an increased risk for development of colon cancer. The aims of this study were to use a previously established rat model of colitis to develop a new model of colitis-associated colon cancer and ascertain the involvement of three cancer-related genes: K-ras, adenomatous polyposis coli (APC), and p53. Four groups of rats were used: reactivated 1,2-dimethylhydrazine [DMH; trinitrobenzene sulfonic acid (TNBS) was used to induce colitis followed by a weekly s.c. dose of DMH], prolonged reactivation (inflammation was induced with TNBS, then maintained twice a week), saline-DMH (animals received saline instead of TNBS followed by a weekly dose of DMH), and normal (received no treatment). Animals were sacrificed at 5, 10, or 15 weeks, and colon samples were taken for pathologic analysis and gene mutation detection. No dysplasia was found in the normal group. The highest incidences of dysplasia were as follows: prolonged reactivation group at 5 weeks (60%), reactivated DMH group at 10 weeks (83%), and saline-DMH group at 15 weeks (67%). Carcinoma was found in both the prolonged reactivation and saline-DMH groups. No mutations were found in the K-ras oncogene; however 62% of the APC samples (exon 15 at nucleotide 2778) and 76% of p53 (exon 6 at nucleotide 1327) showed substitutions. The prolonged reactivation group may be considered a new model of colitis-associated colon cancer, offering the potential to study cancer prevention strategies for patients with IBD.     

Gastrointestinal carcinoma-associated antigen detected by a monoclonal antibody in dysplasia and adenocarcinoma associated with chronic ulcerative colitis

Colorectal tissue specimens from 13 patients with chronic ulcerative colitis, of whom all had epithelial dysplasia and 2 had adenocarcinoma, were tested for the presence of gastrointestinal carcinoma-associated antigen (GICA), using an immunoperoxidase technique with a monoclonal antibody (MAb) against this antigen. GICA was present in the formaldehyde-fixed and paraffin-embedded sections of dysplastic and cancer tissue but absent from normal or hyperplastic epithelium. However, the pattern and extent of staining with the antibody did not correlate with the degree of dysplasia, i.e., "mild" dysplasia was often positive, and "severe" dysplasia was sometimes negative. Changes classified as "indefinite for dysplasia but probably negative" were variable in their expression of GICA. The adenocarcinomas were selectively labelled within cell clusters. In contrast, ulcerative colitis (UC) patients with severe inflammatory changes but with no detectable dysplasia were negative for GICA. GICA could be eluted from paraffin blocks of dysplastic tissue and biochemically characterized as a glycolipid. The detection of this antigen might be a useful complement to morphological examination in discriminating between precancerous and benign epithelial lesions of the colon.     

Urokinase-type plasminogen activator in colorectal carcinomas and adenomatous polyps: quantitative expression of active and proenzyme

Total urokinase-type plasminogen activator (u-PA) content (proenzyme plus active enzyme) was significantly higher in 20 colorectal carcinomas and in 27 adenomatous polyps than in metaplastic polyps and autologous normal mucosa. u-PA content was also markedly increased in adenomatous polyps and autologous colonic mucosa removed from familial polyposis coli patients. Using a new monoclonal antibody technique to distinguish the proenzyme of u-PA from the active enzyme, we found that 70% of the u-PA in polyp and cancer tissue was present in the proenzyme form compared to 47% in normal colonic mucosa. For colon cancers, there was a significant correlation between their stage of invasiveness and the levels of proenzyme. No correlation was observed between the u-PA content of adenomatous polyps and their size or degree of dysplasia. Study of the u-PA content of the colonic mucosa may offer a useful biochemical correlate of epithelial cell transformation in the colon.     

Inducible heat shock protein 70 prevents multifocal flat dysplastic lesions and invasive tumors in an inflammatory model of colon cancer

Background: Heat shock protein 70 (Hsp70) regulates proteinbiosynthesis and refolding of denatured proteins. Since Hsp70participates in recovery from stress injury, we examined theeffect of Hsp70 genetic deletion in the azoxymethane (AOM)/dextransulfate sodium (DSS) model of inflammation and colon cancer.Methods: Hsp70 mutant mice (Hsp70.1^–/–/70.3^–/–)and wild-type (WT) littermates received AOM and three cyclesof DSS and were killed 24 weeks later. Tumors were graded forhistology and immunostained for p53, adenomatous polyposis coli,β-catenin, cyclooxygenase-2 (Cox-2) and inducible nitricoxide synthase (iNOS) and sequenced for p53 mutations. Results:Elevated adenomas developed in 4/10 WT mice with no dysplasiain adjacent mucosa. In contrast, 7/8 Hsp70 knock out (KO) micedeveloped chronic mucosal inflammation and multifocal areasof flat dysplasia and 4/8 progressed to invasive carcinomasarising in a background of flat dysplastic mucosa. These differencesin the incidence of flat dysplasia and invasive cancers weresignificant (P < 0.05). Nuclear p53 was stronger in Hsp70KO tumors compared with WT tumors, and sequencing confirmedp53 mutations in 2/5 tumors from Hsp70^–/– versus0/5 in WT mice. In Hsp70 WT tumors, β-catenin was predominantlynuclear, compared with membranous β-catenin in Hsp70^–/–tumors, suggesting that Hsp70 regulates β-catenin in colonictumorigenesis. Cox-2 and iNOS levels were increased in tumorsfrom Hsp70^–/– mice compared with Hsp70 WT tumors.Conclusions: Hsp70-deleted mice treated with AOM/DSS developflat invasive colonic tumors that mimic many histological andmolecular features of ulcerative colitis colon cancer. Thismodel will be useful to dissect the role of Hsp70 in inflammatorybowel disease colon cancer. Abbreviations: AOM, azoxymethane; Apc, adenomatous polyposis coli; Cox-2, cyclooxygenase-2; DSS, dextran sulfate sodium; Hsp70, heat shock protein 70; IBD, inflammatory bowel disease; IL, interleukin; iNOS, inducible nitric oxide synthase; PCR, polymerase chain reaction; UC, ulcerative colitis; WT, wild-type     

Histochemical profile of mouse hepatocellular adenomas and carcinomas induced by a single dose of diethylnitrosamine.

In continuation of earlier studies on murine neoplastic liver lesions, we characterized by histochemical methods the phenotype of hepatocellular adenomas and carcinomas induced by single injections of diethylnitrosamine (1.25, 2.5, or 5.0 micrograms/g of body weight) in 15-day-old C57BL/6 x male C3H F1 mice. The hepatocellular adenomas were composed predominantly of basophilic cells but stored excessive amounts of fat and glycogen in large portions of the tumors. Irrespective of the carcinogenic dose, the adenomas showed a consistent histochemical pattern. Glycogen synthase and phosphorylase were highly active in the hepatocytes that stored glycogen. In cells poor in, or free of, this polysaccharide, these enzymes were only moderately active or even inactive. In glycogen-storing parts of the adenomas, the activity of adenylate cyclase was reduced compared with normal liver parenchyma, but in fat-storing portions it was elevated. In a few adenomas, uniform increase in adenylate cyclase activity could be encountered. The levels of ATPase, acid phosphatase, and glucose-6-phosphatase were either increased or decreased. Glucose-6-phosphate dehydrogenase and glyceraldehyde-3-phosphate dehydrogenase showed an increased activity in all adenomas compared with preneoplastic foci, which in turn exhibited a higher glucose-6-phosphate dehydrogenase and glyceraldehyde-3-phosphate dehydrogenase activity than the surrounding parenchyma or the liver of untreated controls. The hepatocellular carcinomas showed remarkable histochemical changes compared with adenomas. The levels of fat and glycogen and the activities of glycogen synthase, phosphorylase, and in most cases also that of glucose-6-phosphate dehydrogenase, were reduced significantly. In contrast, adenylate cyclase, glucose-6-phosphatase, glyceraldehyde-3-phosphate dehydrogenase, and also alkaline phosphatase showed a striking elevation in developing carcinomas. Similar, although more pronounced, histochemical changes were seen in the advanced hepatocellular carcinomas. These observations indicated that progression from adenomas to hepatocellular carcinomas was associated with a change in the activity of several enzymes involved in cell membrane function, glycogen metabolism, the oxidative pentose phosphate pathway, and glycolysis.     

Expression of LeY and extended LeY blood group-related antigens in human malignant, premalignant, and nonmalignant colonic tissues

The LeY determinant, a difucosylated type 2 blood group-related antigen, is a positional isomer of the Leb blood group antigen and a fucosylated derivative of the LeX antigen. The LeX antigen behaves like an oncodevelopmental tumor-associated antigen in human colon cancer, and extended polyfucosyl LeX antigens are more specific for colon cancer tissues than are simple, monofucosyl LeX antigens. The present investigation compared the expression of simple and extended LeY antigens in a variety of malignant and nonmalignant human colonic tissues to gain insight into the normal distribution and cancer-associated expression of these antigens. Monoclonal antibody AH-6, which recognizes the LeY epitope irrespective of its carrier carbohydrate chain, stained the majority of specimens regardless of malignant potential or location within the colon. In contrast, CC-1 and CC-2 monoclonal antibodies, which recognize extended LeY structures, and KH-1, which is specific to trifucosyl LeY, preferentially stained malignant colonic tissues and rarely stained normal colonic mucosae. Mucosa immediately adjacent to cancer usually stained with AH-6 but not with KH-1, CC-1, or CC-2. Extended or trifucosyl LeY antigen expression was limited exclusively to premalignant (adenomatous) polyps and was invariably absent from nonpremalignant (hyperplastic) polyps. Moreover, among adenomatous polyps, extended LeY antigen expression tended to correlate with three parameters of malignant potential: larger polyp size; villous histology, and severe dysplasia. AH-6 failed to distinguish between hyperplastic and adenomatous polyps. In second-trimester fetal colonic mucosa, AH-6 bound to both proximal and distal segments whereas KH-1, CC-1, and CC-2 bound only to proximal segments. We conclude that in human colon, the LeY hapten is an oncodevelopmental cancer-associated antigen and extended LeY antigens are highly specific markers for malignancy and premalignancy.     

Ulcerative colitis and familial polyposis oncologic transformation to colon carcinoma: Changes in carcinoembryonic antigen release

During cell proliferation, several “factors” are released into the microenvironment, or culture medium. The experiments described sought and examined agents that may cause or support malignant cell transformation. The response of colon cells from patients with ulcerative colitis (UC), familial polyposis coli (FPC) and colon carcinoma (CCC) to these agents was monitored by carcinoembryonic antigens (CEA) released into the medium during cell proliferation in a serum-free hormone-defined (SFHDM) medium, oncogenicity in athymic mice and colonigenicity, i.e. the ability of the cells to form colonies in soft agar. When cultured on the extracellular matrix (EM), i.e. footprints from colon carcinoma cells (short term or established cell lines), and in SFDHM, colon cells from patients with UC and FPC showed significant (P = 0.001) increases in all the three parameters.Analyses indicated that EM from cultures of [³⁵S]methionine-labelled normal epithelial colon cells (NCE) differed from those left by UCC, FPC and CCC cell cultures. EM from NCE cell cultures did not contain [³⁵S]methionine-labelled glycoproteins resistant to collagenase action which were not fragments of fibronectin, and which were present in EM from CCC cells. It is concluded that the extracellular matrix from malignant colon cells contains agents that support colon cell oncogenic transformation.     

Relative value of oestrogen receptor assay, lactoferrin content, and glucose-6-phosphate dehydrogenase activity as prognostic indicators in primary breast cancer

Oestrogen receptor content, lactoferrin, hexokinase, and glucose-6-phosphate dehydrogenase levels were measured in cytosol from 25 primary breast cancers and 3 fibroadenomas. Both hexokinase and glucose-6-phosphate dehydrogenase activity were higher in malignant tissue as compared to benign breast lesions. Oestrogen receptor concentration and lactoferrin content failed to predict the development of metastatic disease, while glucose-6-phosphate dehydrogenase activity was significantly higher in cytosol from those tumours which subsequently metastasized compared to those which remained localized.     

Phenotypic instability in focal and nodular lesions induced in a short term system in the rat liver

A comparative morphologic, morphometric and enzyme histochemicalinvestigation of lesions induced by short-term application ofN-nitrosomorpholine (NNM) and subsequent so-called ‘selectionpressure’ was carried out in order to assess the characteristicsof the numbers of induced putative preneoplastic populationsand to cast light on reversibility associated with this model.The glycogen storage foci, mixed cell foci and neoplastic nodulesobserved after ‘selection pressure’ were in principlesimilar to those seen after stop experiments, although alterationsin morphology and enzyme phenotype of individual cells wereusually far more pronounced after short-term induction. It wasestablished that 75% of the lesions were no longer visible 11weeks after withdrawal of induction stimuli and that a largeproportion of these remaining demonstrated heterogeneity inmorphological and histochemical markers indicative of reversionto normal phenotype. After a further 10 weeks a slight increasein number of foci associated with decrease in size and enhancedhomogeneity in phenotypic markers was established. The behaviourof foci and nodules undergoing reversion was considered withrespect to changes in basophilia and glycogen storage and activityof the enzymes glucose-6-phosphate dehydrogenase, glucose-6-phosphatase,glyceraldehyde 3-phosphate dehydrogenase, glycogen phosphorylaseand synthase, acid phosphatase and -glutamyl transpeptidaseand correlated with location of altered cellular populationswithin the liver functional acinus.     

Colorectal cancer complicating ulcerative colitis: an institutional series.

Ulcerative colitis predisposes to colorectal cancer: the risk increases along with disease duration and extension. Also some subsets of patients are at increased risk, namely patients with early onset of colitis, and patients with primary sclerosing cholangitis. Cancer complicating ulcerative colitis affects evenly all the colon, and is not located more frequently in the rectum and in the sigmoid colon, as well as the sporadic counterpart. Multiple cancers and cancers associated with high grade dysplasia are not infrequent in ulcerative colitis; for this reason, and for controlling the colitis, the treatment of choice is total colectomy, with or without colostomy. The prognosis of cancer complicating ulcerative colitis is similar to the sporadic counterpart. The Authors present a colon cancers series as a complication of colitis occurred at Regina Elena Cancer Institute of Rome, Italy, over the period 1975-1998.     

Immunohistochemical demonstration of increased glucose-6-phosphate dehydrogenase in preneoplastic and neoplastic lesions induced by propylnitrosamines in F344 rats and Syrian hamsters

Changes in the level of expression of glucose-6-phosphate dehydrogenase (G6PD) within propyl nitrosamine-induced preneoplastic and neoplastic lesions in F344 rats and Syrian golden hamsters were investigated using an immunohistochemical approach. Previously demonstrated increases in G6PD activity in rat liver and hamster pancreatic foci of altered cells were revealed as being due to elevation in the quantity of enzyme protein, suggesting an underlying change in gene expression. Furthermore, strong positive binding of G6PD antibody in thyroid, lung, urinary bladder and kidney lesions indicated that increase in this enzyme protein might be a common marker for neoplastic alteration, regardless of organ. While the function of elevated G6PD may be related to growth requirements, the finding that preneoplastic lesions in some cases bind more strongly than more malignant populations suggests additional involvement of the enzyme in other biochemical pathway(s) relevant to tumorigenesis.     

Frequent loss of a p53 allele in carcinomas and their precursors in ulcerative colitis

Allelic deletions of the p53 gene previously were demonstrated by Southern hybridization to occur in high frequency in sporadic colon carcinomas and in a variety of other human tumors. We have examined the frequency of allelic loss of the p53 gene in carcinoma and dysplasia arising in patients with chronic ulcerative colitis who are heterozygous for the codon 72 polymorphism in exon 4 of the p53 gene. Cells derived from carcinoma and dysplasia specimens from 10 patients who were heterozygous at this locus were sorted by flow cytometry on the basis of DNA content. The p53 exon 4 region was amplified from diploid and aneuploid populations, via a polymerase chain reaction (PCR), and digested with BstUI. Three of three carcinomas, four of six dysplasias, and one patient who was indefinite for dysplasia demonstrated evidence of allelic loss of the p53 gene. Seven of ten cases of sporadic colon carcinoma, analyzed for comparative purposes, exhibited loss of a p53 allele. These results demonstrate that PCR analysis, followed by restriction endonuclease digestion of a polymorphic locus, can provide a rapid, definitive method for analyzing loss of heterozygosity in small numbers of cells from colonic mucosa. Such loss precedes cancer in ulcerative colitis and can be present in its earliest histologically identifiable precursor.