Biochemical changes in premalignant intestines

The immunological properties of thymidine kinase from a variety of human tumors suggest that the form of the tumor enzyme resembles that found in the placenta and in the nondividing colonic flat mucosa. To examine the placenta-like characteristics of tumor thymidine kinase, the jejunum and colon from rats ranging in age from fetal to old and from animals treated with dimethylhydrazine (DMH), an intestinal carcinogen, have been studied. In normal jejunum, thymidine kinase activity decreased rapidly with age. Both the activity and the response to phospholipase C and to mercaptans in DMH-induced tumors resembled that of fetal gut, while those in abnormal appearing DMH-treated jejunum were intermediate between normal control of the same age and tumor. Similar but less pronounced changes were seen in the colon. In the jejunum, the level of another enzyme normally associated with rapid cell division, ornithine decarboxylase, was found to be over 100 times that of the liver, colon, and stomach. Treatment of the animals with acetylaminofluorene and with DMH resulted in elevated levels of the enzyme in liver and in colon, respectively, but had little effect on this enzyme in other tissues. The data presented indicate that there were premalignant changes in the levels of both of these enzymes in target tissues of animals treated with carcinogens.

[Concentration of free glutamine and glutaminase activity in the gastric mucosa of patients with precancerous diseases and cancer of the stomach]

Free glutamine content and phosphate-dependent glutaminase activity were studied in the biopsy specimens from the tissue of ulcer, polyps, carcinoma and the surrounding gastric mucosa of patients with precancerous diseases and carcinoma of the stomach. The glutamine content in carcinoma was not significantly different from that in the normal gastric mucosa. The glutamine level in the gastric mucosa remote from the tumour was considerably higher than normal. In case of polyposis of the stomach glutamine was present in the polyps and absent in the remote gastric mucosa. A marked glutaminase activity was revealed in the carcinoma of the stomach, but its level did not differ from the normal or in the case of precancerous diseases.

Biochemical changes in preneoplastic rodent intestines

Two enzymes were examined as potential indicators of early precancerous changes. Ornithine decarboxylase, an enzyme normally associated with rapid cell division, is low in the rapidly dividing, cancer-susceptible colon. The level of this enzyme was also very high in the nondividing cells of the small intestines. Administration of an intestinal carcinogen, dimethylhydrazine, led to a large increase in colonic ornithine decarboxylase but did not affect the enzyme in liver. A liver carcinogen, acetylaminofluorene, induced manyfold increases in ornithine decarboxylase of the liver but not of the colon. Studies of thymidine kinase of the gut showed that this enzyme changed quantitatively and qualitatively throughout the life of the animal, from fetal rat to newborn and adult. The tumor enzyme has many fetal-like properties. Long-term treatment with dimethylhydrazine led to changes in thymidine kinase reminiscent of the fetal enzyme. Short-term treatment caused sharp increases in the thymidine kinase of nondividing cells of the jejunum and the proximal end of the colon; similar changes in the distal end of the colon were slower in appearing and less pronounced.

Sequential phenotypic changes in hyperplastic areas during hepatocarcinogenesis in the rat

Sequential phenotypic changes in hyperplastic areas of rat liver during N-2-fluorenylacetamide feeding were studied by enzyme and immunohistochemical methods combined with radioautography. Hyperplastic area showed a marked deficiency of beta-glucuronidase and serine dehydratase during their developing phase, the 6th through the 9th experimental weeks, and were fairly specifically labeled by injections of tritiated thymidine after partial hepatectomy performed at the 9th week. A sequential observation on these labeled hyperplastic areas revealed a considerable elevation of the levels of these marker enzymes in the majority of the labeled areas in 3 to 18 weeks after labeling. On the other hand, there was a small group of hyperplastic areas in which the enzyme deficiency persisted during the observation period. This type of lesion was generally larger than those showing enzymic maturation. Labeled cells were not detectable either in distinct hyperplastic nodules at late phase or in carcinomas. The metabolic regulation in the cells comprising hyperplastic areas was studied by checking the induction and repression of serine dehydratase after dietary stimuli. Serine dehydratase was not inducible in hyperplastic areas during the developing phase or in areas with persistent enzyme deficiency, but it was clearly induced and repressed in areas where there was an elevation of the endogenous enzyme level. The areas of hyperplasia with persistent enzyme deficiency and growth appeared to be more important than the ones of phenotypic maturation in relation to the later development of carcinoma. The phenotypic maturation in hyperplastic areas might represent reversion of altered cells towards normalcy from the condition related with neoplastic transformation.

Kinetics of induction and growth of enzyme-deficient islands involved in hepatocarcinogenesis

A single application of various hepatocarcinogens to rats results in the formation of islands of enzyme-deficient liver cells, which are mainly irreversible and very probably represent the first cellular stage involved in the process of liver cancer formation. Comparison of the island-size distributions obtained for different carcinogens indicated that proliferation is a common property of islands that is independent of the inducing carcinogen and does not need any further presence of carcinogen or other stimulating factors. Toxic doses resulted in all cases in an enhanced island size. The number of islands induced by a single dose of carcinogen was enhanced by a prior partial hepatectomy only in the case of the dialkylnitrosamines, dimethylnitrosamine, and diethylnitrosamine. Dose-response relationships measured with diethylnitrosamine, the carcinogen with the lowest toxicity as compared with the carcinogenic action, indicated that island formation is due to a one-hit process, i.e., that one specific alteration in the target cell is responsible for the precancerous transformation. These kinetics and the low probability of transformation might indicate that the crucial hit is scored at the genetic level. The irreversible action of carcinogen (memory effect) and the influence of time on cancer formation (time effect) are discussed in terms of induction and proliferation of irreversible cell populations serving as precursor of the cancer cell. The number of specific alterations (hits) involved in the development of the malignant cancer cell is also briefly discussed.

Transfer RNA methylase activity and capacity during aflatoxin B1-induced hepatocellular carcinogenesis

Transfer RNA methylase (tRNA methylase) activity and capacity were monitored in whole-rat-liver preparations during the induction of hepatocellular carcinomas by an 8-week aflatoxin B1 dosing regimen that produced minimal toxic effects. Significant phases of elevated tRNA methylase capacity occurred at 6 to 9 weeks (20%) and 24 to 29 weeks (40%). No significant change in tRNA methylase activity was noted over the course of the 55-week experiment. Higher aflatoxin B1 doses, producing acute toxic liver damage, resulted in elevated tRNA methylase activity (50%) and capacity (30%) at least as early as 1 week after dosing. Experiments with individual nodular lesions excised from livers of rats continuously fed a diet containing 2 ppm aflatoxin B1 demonstrated similarly elevated tRNA methylase activities and capacities in hyperplastic (preneoplastic)nodules, with and without histological evidence of carcinoma.

Early changes of glandular stomach in Wistar rats ingesting N-methyl-N'-nitro-N-nitrosoguanidine (MNNG): with special reference to light microscopic, electron microscopic, and enzyme histochemical study of the regenerating epithelium induced by MNNG

Early mucosal changes of the glandular stomach in Wistar rats ingesting N-methyl-N'-nitro-N-nitrosoguanidine were studied. Special attention was paid to clarifying the localization and chronological relationship between the expected regenerative changes and the succeeding carcinoma. For this purpose, drinking water of MNNG at a low concentration was given to the inbred Wistar rats which were sacrificed every second week during the first 35 weeks. In the 5th week, localized erosions appeared, which were constantly observed through about the 20th week. These changes were always located near the midpoint of the lesser curvature. Epithelial cells, which were found there, were studied with light and electron microscope, and with enzyme histochemistry. It has been observed that these cells corresponded with the so-called immature cells in the normal gastric epithelium and also with the regenerating epithelial cells, which were obtained from the vicinity of mechanically induced ulcer of the stomach. From about the 20th week 2 cases showing ectopic gland, 4 adenomatous changes, 2 early carcinomas, and 5 invasive carcinomas were found. All these lesions were located on the lesser curvature, near its midpoint, i.e. exactly the same area where regularly the erosions were observed.

[Acid phosphatase activity in breast dysplasias and in carcinomas of the breast]

The histochemical reactions of acid phosphatase were studied in tissues deriving from normal breasts, from mammary dysplasia, and from breast carcinoma. Acid phosphatase was demonstrated in all cases with more intense activity in breast carcinoma where activity was particularly accentuated in the stroma. In benign tumours and fibroadenosis, phosphatase was prevalently localized in the periductal cells and within the ducts. Exceptions were the cases of fibroadenosis with acute or chronic collateral inflammation where phosphatase granules were located in the stroma also, even though they were always quantitatively inferior to the corresponding localization of cases of breast carcinomas.

Multiple molecular forms of glucose-6-phosphate dehydrogenase in normal, preneoplastic, and neoplastic mammary tissues of mice

Multiple molecular forms of glucose-6-phosphate dehydrogenase (G6PD) in normal, preneoplastic, and neoplastic mammary tissues were separated by polyacrylamide gel electrophoresis and identified by specific straining for enzyme activity. Mammary tissue from lactating BALB/c mice showed considerable amounts (up to 50%) of a slower-migrating G6PD species, G6PD-III, which was essentially absent from glands of pregnant mice, preneoplastic nodules, and mammary carcinomas. All tissues possessed a faster-migrating species, G6PD-II, which accounted for up to 85% of the total G6PD in the glands of pregnant mice. A third species, G6PD-I, migrating more rapidly than G6PD-II, was found in both abnormal tissues (preneoplastic and neoplastic) and accounted for up to 35% of the total enzymatic activity. G6PD-I was present in moderate amounts (less than 15%) in glands from pregnant mice and was essentially absent from the lactating gland (approximately 5%). The addition of dithiothreitol did not alter the measurable G6PD activity but did increase the relative activity of G6PD-II or G6PD-I, as judged by the intensity of the bands on the gels. Mild oxidation (stirring overnight at 4 degrees in air) resulted in a loss of G6PD activity, but preparations had greater amounts of G6PD-III; presence of dithiothreitol during aeration partially prevented loss of G6PD activity and largely prvented the appearance of G6PD-III. Molecular-weight estimations with preparations from lactating mice yielded a value of 118,000 for G6PD-II and 260,000 for G6PD-III, suggesting a monomer and dimer, respectively. The addition of nicotinamide adenine dinucleotide phosphate stabilized G6PD activity by preventing heat inactivation at 47 degrees; nicotinamide adenine dinucleotide phosphate did not alter the pattern of species present. The data from heat inactivation studies suggest that G6PD-III (dimer) was the more stable species. The addition of nicotinamide adenine dinucleotide phosphate to samples after oxidation in the absence of dithiothreitol (about 70% loss of activity) resulted in no change in patterns and in recovery of full G6PD activity during heating at 47 degrees. A potential relationship between glutathione reductase activity and the pattern of G6PD species observed in the various tissues is noted.

The steroid alcohol and estrogen sulfotransferases in rodent and human mammary tumors

Rodent and human mammary tumor systems were investigated to relate the steroid alcohol and estrogen sulfotransferase activities to the hormoanl dependency of the tumor as determined by estrogen receptor content. Unlike the normal mammary gland or the hyperplastic alveolar nodule, rodent mammary neoplasms displayed significant levels of these two sulfotransferases. In the hormone-independent mouse tumors produced from out-growth lines D1, D2, and D8, high dehydroepiandrosterone sulfotransferase activity was characteristic of the rapidity with which hyperplastic alveolar nodules developed into a neoplasms (V-max = 52.8 versus 1.8 fmoles/min/mg protein) while estrone sulfotransferase activity was either not detectable or low (V-max = 5.5 fmoles). After oophorectomy of mice bearing slowly developing tumors, both sulfotransferases in the nonregressing neoplasms showed marked increases in activity (V-max dehydroepiandrosterone = 30.0 fmoles; V-max estrone = 18.5 fmoles). Strain differences not the estrogen receptor content of hormone-dependent rat mammary tumors. In Wistar-Lewis rats the steroid alcohol sulfotransferase activity was at least 35 times higher than in the Sprague-Dawley strain. As was observed in the mouse mammary tumor, Sprague-Dawley rat neoplasms that grew in the absence of ovarian hormones contained significantly greater levels of the steroid alcohol sulfotransferase. Possible correlaion between presence of the steroid alcohol sulfotransferase and the estrogen receptor protein was observed in a limited number of human breast carcinomas.

Prostatic fluid lactic dehydrogenase isoenzyme patterns of prostatic cancer and hyperplasia

LDH isoenzyme patterns were determined in prostatic fluid from 286 patients with a prostate gland judged to be normal, the site of benign hyperplasia on clinical evidence or the site of benign hyperplasia or carcinoma on the basis of histologic evidence. Fluid from 12 of 15 patients (80 per cent) with carcinoma representing all stages and grades of disease showed an LDH-V/I ratio of more than 3. This ratio was exceeded in only 6 of 57 (11.8 per cent) and 14 of 97 (14.4 per cent) patients in whom the diagnosis of benign prostatic hyperplasia without evidence of infection was established histologically or clinically, respectively. An LDH-V/I ratio exceeding 3 was seen commonly in patients with a diagnosis of benign prostatic hyperplasia with a recent history suggesting infection and more than 10 WBCs per high power field on microscopic examination of the prostatic fluid. These observations suggest that an LDH-V/I ratio exceeding 3 in the prostatic fluid in the absence of a history of infection and more than 10 WBCs per high power field on microscopic examination should be regarded as an indication of a high risk of the presence or development of a malignancy of the prostate. The results obtained also support the concept that, in the presence of malignancy, expressed prostatic fluid provides an adequate sample of cells with altered metabolism.

The regulation of serine dehydratase and glucose-6-phosphatase in hyperplastic nodules of rat liver during diethylnitrosamine and N-2-fluorenylacetamide feeding

Changes in the levels of serine dehydratase and glucose-6-phosphatase induced by dietary stimuli or starvation in hyperplastic nodules of rat liver during diethylnitrosamine or N-2-fluorenylacetamide feeding were studied by immuno- and enzyme histochemical methods. The study was performed during carcinogenesis through a combined method of enzyme histochemistry and radioautography. Serine dehydratase was observed diffusely in the cytoplasm of the original hepatocytes in the periportal zone and was induced markedly during diethynitrosamine feeding but only slightly during N-2-fluorenylacetamide feeding. The enzyme was deficient and not inducible in hyperplastic nodules during their developing phase. Later during the feeding period, however, there was an elevation of the level of serine dehydratase and its inducibility with time in the majority of the nodules. A good correlation was observed between serine dehydratase and glucose-6-phosphatase in their elevated levels and response to enviornmental stimuli. There was a minor group of hyperplastic nodules in which the deficiencies of these enzymes persisted and enzyme induction was not observed. A greater number of hyperplastic nodules with persistent enzyme deficiency was seen during diethylnitrosamine carcinogenesis. These results provide further information about the changing biological nature of hyperplastic nodules with respect to their metabolic adaptability and enzyme levels during hepatocarcinogenesis.

Cell proliferation and subcellular localization of alkaline phosphatase activity in rat liver parenchyma during azo dye carcinogenesis

A combined method of phosphatase histochemistry and (3H)thymidine radioautography was devised to study the subcellular localization of alkaline phosphatase (AP) activiity with changing pattern of cell proliferation in precancerous livers of rats fed dimethylaminoazobenzene. After 50 hr of continuous infusion of (3H)thymidine into the rats, labeled liver tissue were fixed in glutaraldehyde. Sections were incubated for AP activity in a lead citrate medium (pH 9.4) with beta-glycerophosphate as substrate. Light and electron microscopic examinations of radioautographs revealed that focal groups of 3H-labeled hepatocytes within hyperplastic nodules were coincident to hyperbasophilic foci and distinguishable from the surrounding parenchyma, which was sparsely labeled. Proliferative hepatocytes in the foci exhibited enzyme reaction product indicative of AP activity along the entire surface membranes. The surface AP tography was in contrast to that of the surrounding hyperplastic parencyma, in which regenerative hepatocytes showed a normal localization of AP activity at the bile canalicular membranes. The L-phenylalanine-sensitive snd heat-resistant activity of hyperbasophilic hepatocytes was different from that of normal hepatocytes. The surface enzyme differentiation was accompanied by a decrease of cytoplasmic AP. Golgi elements apparently function in the mobilization of AP into the surface membranes. The phenomena of AP alterations might be related to the abnormal control of cell proliferation and cytodifferentiation leading to malignant growth.

The glycolytic enzyme activity of the human cervix uteri

The activity of the following enzymes was studied in normal, precancerous, and malignant biopsies from the human cervix uteri: hexokinase (HK), phosphofructokinase (PFK), pyruvate-kinase (PK), lactate dehydrogenase (LDH), and glucose-6-phosphate dehydrogenase (G-6-PDH). In precancerous conditions, i.e., dysplasia and carcinoma in situ without any signs of invasive carcinoma, only PK showed moderate but significant activity increases. A rise in enzyme activity in biopsies histologically classified as carcinoma in situ was found to signal the presence of invasive carcinoma in other parts of the cervix. In invasive carcinomas of the cervix, all the enzymes studied showed a two- to four-fold increase (p less than 0.01) as compared to the normal cervix. The present study failed to reveal significant differences between enzyme activities in biopsies from patients in Stage I, II, and III; no correlation could be established between enzyme activity and prognosis.

Alkaline phosphatase activity in hyperplastic and neoplastic urinary bladder epithelium of mice fed 2-acetylaminofluorene

Studies were made on the urinary bladder of 66 BALB/c mice of both sexes; 21 were fed a normal diet and 45, a diet containing 100-500 parts per million (ppm) of 2-acetylaminofluorene (2-AAF). Bladder epithelial hyperplasia was noted in 22 of 24 mice given 2-AAF for 7 months and in 20 of 21 given 2-AAF for 19 months. Transitional cell carcinomas were in 12 of 21 mice given 2-AAF for 19 months and in all except the 9 females given the low dose (100 ppm). Special stains revealed marked alkaline phosphatase activity in the bladder epithelium of untreated controls and slightly to moderately reduced activity in the hyperplastic epithelium, particularly the lower layers, of mice given 2-AAF for 7 months. Activity was markedly reduced and confined largely to the upper layers in mice treated for 19 months. The transitional cell carcinomas showed no activity except focally in a few tumor masses in 11 of 12 mice with tumors. Alkaline phosphatase activity was usually slightly to moderately increased in the sub-epithelial stroma after 7 months' treatment with 2-AAF and markedly increased after 19 months. Loss of alkaline phosphatase activity in the bladder epithelium may be a preneoplastic change.

Studies of lactic dehydrogenase content in rectal mucosal biopsies

The total lactic dehydrogenase (LD) content and LD isoenzyme ratios were studied in homogenized rectal mucosa from 31 patients with established non-specific mucosal ulcerative colitis and from 16 normal subjects. The total LD content was found to be significantly increased in patients with active ulcerative colitis when compared with patients with inactive colitis or with normal subjects. There was a similar though not a significant increase in the slow moving isoenzymes of LD in samples of rectal mucosa from patients with active colitis. The LD isoenzyme pattern was in the normal range in two of the three patients with histological premalignant changes in rectal biopsy specimens. There was a statistically significant linear correlation between the total lactic dehydrogenase content of rectal mucosa and the carcino-embryonic antigen levels in whole serum. Both the total content and isoenzyme ratios of LD were increased in neoplastic tissue obtained from patients with carcinoma of the colon and with tissue from benign rectal polyps.

Control of glucose-metabolizing enzymes in preneoplastic rat liver

Studies of the transient changes in the maximum catalytic capacities of glucose-metabolizing enzymes in preneoplastic rat liver revealed significant decreases in the activities of only two enzymes, glucokinase and hexosediphosphatase. The activities of hexokinase, glucose-6-phosphate dehydrogenase, and phospho-gluconate dehydrogenase increased threefold and there was a significant elevation of liver enzymes in the serum after 45 days of carcinogen treatment.

Histochemical studies of papillary hyperplasia of the palate: enzyme histochemistry of papillary hyperplasia and normal palatal mucosa

Representative enzymes from four enzyme groups, which have been related to premalignant or malignant activity, were studied histochemically. Tissues from patients with papillary hyperplasia, normal denture-wearing patients, and normal non-denture-wearing patients were examined. No differences were noted in the distribution of the enzymes in the different tissues that could be related to premalignant or malignant change.