alpha-D-mannosidase activity in histiocytosis X.

A histochemical study of enzymatic activities was undertaken in five cases of histiocytosis X (two localized bone forms, two generalized forms, and one involving mainly the skin), each of which revealed characteristic structural features at the optical and ultrastructural levels. A confirmation was made of the original assumption of high acid alpha-D-mannosidase activity, i.e. activity described in human Langerhans intraepidermal cells (Elleder, 1975). In the control group of tumors, with the exception of urticaria pigmentosa, enzyme activity was either at trace level or altogether absent. Acid alpha-D-mannosidase activity therefore appears to be the first biochemical feature common to both histiocytosis X and the Langerhans cells. The significance of the finding for the present theory of the histogenesis of the above tumors is discussed.     

17 Beta-hydroxysteroid dehydrogenase in human breast cancer: analysis of kinetic and clinical parameters

In this study, we assessed the rate of estradiol degradation via the 17 beta-hydroxysteroid dehydrogenase (HSD) enzyme in breast tumors from postmenopausal women. We initially studied the effects of time, level of enzyme activity, amount of tissue assayed, and substrate concentration on the linearity of conversion of estradiol to estrone in breast tumor homogenates. The reaction was demonstrated to be linear when less than 15% conversion of estradiol to estrone occurred over 30 min with homogenates produced from 2.5 mg of tissue. Detailed kinetic experiments demonstrated the presence of two classes of enzyme activity, one with high affinity and the other with low affinity. In 83% of the tumors examined, the high affinity form was present and had a median Km of 0.62 microM and Vmax of 82 nmol/g protein/h. In 29 tumors, HSD activity could be precisely quantified and correlated with clinical parameters. No statistically significant correlation of enzyme activity with estrogen receptor (r2 = 0.06) or progesterone receptor (r2 = 0.006) or with patient age could be detected (r2 = 0.001). In 12 additional tumors, activity exceeded 15% conversion of estradiol to estrone at 30 min and precise quantitation was not possible. The average content of progesterone receptor was similar for these 12 tumors as for the 19 with lower HSD activity. However, estrogen receptor content and patient age were lower in the group with high HSD activity. The finding of a high affinity form of HSD in this study provides support for the biological importance of this enzyme in breast cancer tissues.     

Cancer-associated serum galactosyltransferase activity. Demonstration in an animal model system.

Two different lines of solid tumors were produced in outbred hamsters by subcutaneous injection of polyoma transformed BHK cells. Growth of the tumors correlated with the appearance in serum of an electrophoretically distinct peak of galactosyltransferase: NeuAc-, Gal-free fetuin acceptor activity on polyacrylamide gels. This slow moving peak of enzyme activity (GT-HH) was detected before solid tumors could be grossly observed and the amount of activity in this peak was also found to be linearly related with growth of the tumor. GT-IIH was not detectable in control animals and separated from a faster migrating major area of serum galactosyltransferase activity (GT-IH) found in sera of both control and tumor-bearing hamsters. These two activities were shown to maintain their respective mobilities on re-electrophoresis. Solubilized enzyme derived from excised tumors demonstrated an electrophoretic mobility on polyacrylamide gels identical to that for GT-IIH present in serum from tumor-bearing animals. In contrast, enzyme activity solubilized from livers of both control or tumor-bearing hamsters showed a mobility similar to that of the faster moving serum galactosyltransferase enzyme activity, i.e. GT-IH. In addition, medium derived from nonconfluent BHKpy cells in tissue culture contained galactosyltransferase activity which co-electrophoresed with the slower migrating characteristics of galactosyltransferase activities derived from serum (control and tumor-bearing), solid tumors, liver and BHKpy cells in tissue culture were compared. All kinetic properties were similar with the exception that the Km UDP-galactose of GT-IIH (1.0 X 10(-5) M) was half that of GT-IH (2.0 X 10(-5) M).     

Steroid sulfatase and sulfuryl transferase activities in human brain tumors

Neuroactive steroids (dehydroepiandrosterone, pregnenolone) and their sulfates act as modulators of glutamate and γ-aminobutyrate type A receptors in the brain The physiological ratio of these neuromodulators is maintained by two enzymes present in the brain, namely, steroid sulfatase (STS) and steroid sulfuryl transferase (SULT).

Following previous determination of their activities in monkey brains, their activities were evaluated in human brain tumors. Radioimmunoassay and GC-MS were used for determination of products. Both enzyme activities were measured in the 55 most frequent human brain tumors (glioblastomas, pituitary adenomas, meningiomas, astrocytomas).

Significant differences were found in STS activity among investigated types of tumors except the pair of pituitary adenomas-glioblastomas, while significant differences were found in SULT activity among investigated types of tumors.

Spontaneous tendency to form clusters was revealed when both enzyme activities were taken as coordinates. Clustering indicated an individual metabolic behavior of glioblastomas and 72.7% of pituitary adenomas. Astrocytomas, meningiomas and remaining 27.3% pituitary adenomas showed similarities in both enzymes’ activities. Differences in STS and SULT activity did not depend on the sex or age of subjects.     

Metabolism of [4-14C]estradiol by 7,12-dimethylbenz(a)anthracene-induced mammary tumor peroxidase

The peroxidase and estradiol-metabolizing activities of mammary tumors induced by 7,12-dimethylbenz(a)anthracene were determined in fresh and stored tissue. In both cases, a wide variation in peroxidase activity was observed in 47 different tumors tested. The properties of the enzyme found in the tumors were similar to those of lactoperoxidase. It is suggested that the amount of peroxidase present might reflect the ability of tumor cells to differentiate in response to hormonal stimulation and be indicative of the degree of tumor progression.     

Biochemical alterations in 7,12-dimethylbenz[a]anthracene-induced mammary tumors from rats subjected to caloric restriction

Caloric restriction reduces the incidence and progression of a broad spectrum of neoplastic diseases, yet little is known about the biochemical and molecular mechanisms involved. Profiles of enzyme activities of importance in cellular energy utilization were examined in 7,12-dimethylbenz[a]anthracene-induced (DMBA) mammary adenocarcinomas from rats fed ad libitum or calorically restricted diets. The diets provided equal nutrients except for fewer carbohydrate-derived calories; graded caloric restriction was 10, 20, 30 and 40%. The specific activities of hexokinase, pyruvate kinase, lactate dehydrogenase, glucose-6-phosphate dehydrogenase, malic enzyme and fructose-1,6-bisphosphatase were all elevated to varying degrees in both large palpable and small, non-palpable tumors from calorically restricted hosts compared to activities in tumors from ad libitum-fed rats. Phosphofructokinase activity was increased in palpable tumors from calorically restricted hosts but markedly reduced in non-palpable tumors. These results suggest adaptive or compensatory alterations in tumor enzyme profiles in response to the altered nutritional state of the host.     

Glucose-6-phosphatase as a marker for tumors of liver and kidney origin

Glucose-6-phosphatase is primarily a liver and kidney enzyme. This enzyme was studied in various tumors, however, glucose-6-phosphatase activity was found only in tumors of liver, kidney, or adrenal origin. Glucose-6-phosphatase activity was useful in identifying the tissue origin of extrarenal Wilms'. Metastatic tumors within the liver or kidney that originated from other tissues did not have glucose-6-phosphatase activity. Therefore, it is suggested that glucose-6-phosphatase can be used as a specific enzyme marker for tumors of liver and kidney origin.     

Lipid composition of the membranes from cells of two rat tumors and its relationship to tumor thermosensitivity

A plasma membrane-rich fraction has been separated from liver cells and cells of two solid rat tumors. D23 hepatoma and MC7 sarcoma. On the basis of marker enzyme activity the membranes separating at the 31-41% interface on the discontinuous sucrose gradient were enriched 15- to 19-fold. No significant differences in the phospholipid (PL) composition of the three membrane fractions were observed. The PL fatty acid (FA) composition showed that the percentage of unsaturated FA in all three membranes was between 43 and 48%. However, the oleic acid:PUFA ratio was much greater from tumor membranes. Membrane cholesterol was also significantly lower for cells from both tumors compared with liver cells. The DPH fluorescence polarization of the membrane fractions showed that the membranes from cells of both tumors are significantly less ordered than those of liver at all temperatures measured (4-50 degrees C). The Mg2+ ATPase activity of the plasma membranes is inactivated by hyperthermia treatments. The enzyme from liver cells was more thermostable (LT50 = 53.86 degrees C) than that from cells of either D23 (LT50 = 47.51 degrees C) or MC7 (LT50 = 46.34 degrees C) tumors.     

Degradation of intact basement membranes by human and murine tumor enzymes

Homogenates from malignant tumors, obtained from surgery specimens or from transplants of Walker 256 carcinosarcoma in rats, contained an enzyme activity capable of degrading intact 3H-acetylated basement membranes from bovine lens. The enzyme activity from murine tumor was purified about 7500-fold by (NH4)2SO4 fractionation, ion exchange and gel chromatography. The apparent molecular weight of the purified enzyme was approximately 50,000. The rate of degradation of 3H-labelled basement membrane by the murine tumor enzyme was reduced by addition of excess type IV collagen, but not of excess type I, type III or type V collagen. These results suggested specificity of this enzyme for type IV collagen. Inhibitors of serine proteinases, thiol proteinases and soybean trypsin inhibitor were without effect on the enzyme activity. Chelators such as 1,10-phenanthroline or EDTA reduced the activity to control levels, indicating that the enzyme activity was due to a metalloproteinase. Chromatographic and electrophoretic separation of the enzymatic products from 3H-labelled basement membrane and type IV collagen indicated that the enzyme activity was due to a type IV collagenase. The use of basement membrane in the native physiological state as a substrate for the study of basement membrane-degrading activity by homogenates of solid malignant tumors offers an in vitro model for the investigation of the metastatic potential of these tumors.     

Quantitative immunoassay of human deoxycytidine kinase in malignant cells.

Deoxycytidine kinase (dCK) is necessary for the activity of several nucleosides used for the chemotherapy of cancer and AIDS. However, the measurement of dCK catalytic activity in crude cell extracts may be imprecise, due to the presence of phosphatases and nucleotidases that degrade the enzyme products. We describe a simple immunoassay for dCK that can measure accurately as little as 5 ng enzyme protein in crude tissue extracts. The assay enabled us to show (i) that mutant cells deficient in dCK activity lack immunoreactive dCK protein, (ii) that dCK catalytic activity and immunoreactivity correlate closely in human tumors, and (iii) that immunoreactive dCK is particularly high in lymphocytes and lymphoid malignancies, although certain solid tumors may also contain the enzyme. The immunoassay of dCK could prove useful in the selection and monitoring of patients who are being treated with nucleosides that are activated by this enzyme.     

Properties of guanylate cyclase from rat kidney cortex and transplantable kidney tumors.

The subcellular distribution and properties of guanylate cyclase was examined in preparations of normal rat renal cortex and Morris renal tumors MK2 and MK3. In normal kidney cortex about two-thirds of guanylate cyclase activity of homogenates was found in soluble fractions. With renal tumors the homogenate activity was less and the enzyme was equally divided between particulate and soluble fractions. The particulate enzyme in kidney cortex and tumors was associated with all particulate fractions. Triton X-100 increased the activity of all preparations. All preparations preferred Mn2+ as the sole cation. The stimulatory effects of Ca2+ on soluble enzyme and inhibitory effects on particulate activity were similar with preparations of renal cortex and tumors. ATP inhibited all preparations. Soluble and particulate guanylate cyclases from renal cortex were activated several-fold with 1 mM NaN3. Preparations of tumor enzymes did not respond to NaN3. Thus, compared to normal renal cortex the subcellular distribution of guanylate cyclase and some of its properties are altered in preparations of renal tumors.     

In vivo regulation of human leukocyte 3-hydroxy-3-methylglutaryl coenzyme A reductase: increased enzyme protein concentration and catalytic efficiency in human leukemia and lymphoma.

The activity of microsomal HMG-CoA reductase in freshly isolated leukocytes from patients with a variety of hematologic malignancies was significantly increased (up to 20-fold) when compared to enzyme activity in leukocytes from normal subjects (average 10.3 +/- 0.8 pmol/min per mg). Increased enzyme activity was not due to nonspecific leukocyte stimulation or to the presence of a malignancy, since normal enzyme activity was observed in subjects with either viral illnesses or solid tumors. Increased HMG-CoA reductase activity accompanying hematologic malignancy could also not be attributed to alterations in enzyme-substrate kinetic parameters (Km), or to alterations in the phosphorylation state or thiol-disulfide status of the enzyme, nor was it correlated with differences in serum lipid or lipoprotein concentrations. The increase (3.6-fold) in HMG-CoA reductase activity in leukocytes from patients with preleukemia was due entirely to a rise in enzyme catalytic efficiency (specific activity), whereas the increase (4.3-fold) observed in leukocytes from patients with overt leukemia or non-Hodgkin's lymphoma was due to a concomitant increase in both enzyme catalytic efficiency (2.5-fold) and enzyme protein concentration (1.6-fold). Similar increases in HMG-CoA reductase activity and catalytic efficiency were also noted for both transformed, nonmalignant, and malignant cultured leukocytes, suggesting that increased enzyme catalytic efficiency is not a nonspecific consequence of physiological changes occurring in response to the malignancy but may be an integral aspect of the malignant phenotype. HMG-CoA reductase protein concentrations, however, were not elevated in either transformed, nonmalignant, or malignant cultured leukocytes, suggesting that increases in enzyme protein levels may be secondary to other physiological changes that occur during the development of overt leukemia. Taken together, these observations suggest that an increase in the activity of HMG-CoA reductase, the rate-controlling enzyme in cholesterol synthesis, is a common occurrence in human hematologic malignancies and that a biphasic elevation of enzyme activity may exist in malignant leukocytes, such that changes in catalytic activity may occur early in tumorigenesis and may be followed by secondary changes in enzyme levels.     

Modulation of alkaline phosphatases in LoVo, a human colon carcinoma cell line

LoVo, a continuous cell line derived from a human colon carcinoma produces two alkaline phosphatases: the heat-labile, L-homoarginine-insensitive, intestinal form, characteristic of its tissue of origin and the heat-stable, term-placental form, ectopically produced by a variety of tumors. Under basal conditions the activity levels of both enzymes are similar. Hyperosmolality and sodium butyrate induce increased levels of activity of the two alkaline phosphatases in a disparate fashion; whereas hyperosmolality augments the activity of both to the same extent, the effect of butyrate is more pronounced on the activity of the intestinal enzyme. When the two inducers are combined, induction of term-placental alkaline phosphatase is additive and that of the intestinal enzyme is synergistic. The effect of hyperosmolality is blocked by cycloheximide, and induction by sodium butyrate is inhibited by thymidine, cordycepin and cycloheximide. The known alkaline phosphatase inducer, prednisolone, has no effect on the enzymes of LoVo cells. Our results suggest that in these tumor cells the activity levels of the closely homologous term-placental and intestinal alkaline phosphatases appear to be independently controlled.     

immunocytochemical localization of urokinase-type plasminogen activator in lewis lung carcinoma

The invasively growing and metasizing Lewis lung carcinoma consistently contained urokinase-type plasminogen activator (u-PA) enzyme activity. When investigated immunocytochemically with antibodies against u-PA, different parts of individual tumors showed a pronounced heterogeneity in staining intensity. Strong staining was found in areas with invasive growth and degradation of surrounding normal tissue, while other areas were completely devoid of staining. Immunoreactivity occurred both with a perinuclear cytoplasmic localization in tumor cells and associated with apparently extracellular material. SDS PAGE of tumor extracts, under both reducing and nonreducing conditions, followed by immunoblotting, showed only one immunocytochemically stainable band with an electrophoretic mobility corresponding to that of purified proenzyme to u-PA, while no two-chain u-PA was detected. This indicates that the major part of the activator in Lewis lung carcinoma is present as one-chain pro-u-PA.     

Modification of the effects of hyperthermia and neutron radiation on the activity of acid phosphatase in CaNT tumors.

Acid phosphatase activity was measured in implanted murine CaNT tumors of varying volumes. There is a clear monotonically increasing relation between acid phosphatase activity and tumor volume. Also the tumors were subjected to either induced artificial hypoxia or hyperthermia (41.0 degrees C) alone, or combined with neutron irradiation (3.8 Gy). Changes in the activity of this enzyme following radiation damage could reflect tissue damage associated with metabolic disturbances. The effect on enzyme activity after sequential hyperthermia and neutron irradiation is not synergistic, as is shown in the quantitative experimental data. This implies that the mechanisms of heat damage differ from that of neutron beam damage, as reflected by acid phosphatase activity. The CaNT tumor was also shown to be thermosensitive after administration of mitoxantrone. Finally, the role of exogenous ATP was shown to provide heat protection by modification of those thermal effects resulting in the activity of acid phosphatase. The augmentation of this hydrolytic enzyme probably represents initial metabolic damage in the tumor after different modalities of radiation alone, or combined with mitoxantrone and exogenous ATP.     

Reduced fructosamine-3-kinase activity and its mRNA in human distal colorectal carcinoma

Fructosamine-3-Kinase (FN3K) is an enzyme phosphorilating fructoselysine (FL) residues on glycated proteins, resulting in the production of protein-bound FL-3-phosphate. The pathological role of the non-enzymatic modification of proteins by reducing sugars has become increasingly evident in various types of disorders, including the cancer. In this study, our aim was to study FN3K enzyme activity, as well as its mRNA in human colorectal cancer (CRC). Thirty consecutive CRC patients undergoing surgery of the colon were enrolled in the study. FN3K enzymatic activity and gene expression were analyzed using a radiometric assay and quantitative RT-PCR, respectively. FN3K is a functionally active enzyme in human colon tissue, without significant differences between normal mucosa and cancer. The mean level of FN3K mRNA was significantly lower in cancer than in the corresponding normal colorectal mucosa The colorectal tumors located on the left side showed lower levels of both enzymatic activity and mRNA FN3K than tumors located in the right side of colon. This paper is the first studying FN3K enzyme activity in human CRC, showing a significant relationship between enzymatic activity, its mRNA and tumor side.     

D-alpha-Hydroxyglutarate dehydrogenase of Rhodospirillum rubrum.

D-alpha-Hydroxyglutarate dehydrogenase of R. rubrum grown anaerobically in the light was partially purified and some properties were investigated. 1. The enzyme catalyze stoichiometrically the dehydrogenation reaction of D-alpha-hydroxyglutarate into alpha-oxoglutarate, coupled with the reduction of 2, 6-dichlorophenolindophenol. 2. Cytochrome c2, cytochrome c, and ferricyanide are effective as electron acceptors with the crude enzyme but not with the purified one, whereas NAD+ and NADP+ are completely ineffective. The enzyme is thought to play a role in the electron transport system of the organism. 3. D-alpha-Hydroxyglutarate is virtually the sole substrate for the enzyme. The apparent activity against L-alpha-hydroxyglutarate is presumed to be due to contamination of the L-isomer sample with the D-isomer. The enzyme shows barely detectable activity against both isomers of malate and virtually no activity against DL-lactate and glycolate. 4. Both isomers of malate and oxalate, which are presumably substrate analogues, inhibit the enzyme activity. 5. The enzyme is not an inducible enzyme but rather is a constitutive one for R. rubrum, unlike from the enzyme of Pseudomonas putida which is an inducible enzyme for the catabolism of lysine.     

The subcellular distribution and properties of aldehyde dehydrogenases in rat liver

1. Kinetic experiments suggested the possible existence of at least two different NAD(+)-dependent aldehyde dehydrogenases in rat liver. Distribution studies showed that one enzyme, designated enzyme I, was exclusively localized in the mitochondria and that another enzyme, designated enzyme II, was localized in both the mitochondria and the microsomal fraction. 2. A NADP(+)-dependent enzyme was also found in the mitochondria and the microsomal fraction and it is suggested that this enzyme is identical with enzyme II. 3. The K(m) for acetaldehyde was apparently less than 10mum for enzyme I and 0.9-1.7mm for enzyme II. The K(m) for NAD(+) was similar for both enzymes (20-30mum). The K(m) for NADP(+) was 2-3mm and for acetaldehyde 0.5-0.7mm for the NADP(+)-dependent activity. 4. The NAD(+)-dependent enzymes show pH optima between 9 and 10. The highest activity was found in pyrophosphate buffer for both enzymes. In phosphate buffer there was a striking difference in activity between the two enzymes. Compared with the activity in pyrophosphate buffer, the activity of enzyme II was uninfluenced, whereas the activity of enzyme I was very low. 5. The results are compared with those of earlier investigations on the distribution of aldehyde dehydrogenase and with the results from purified enzymes from different sources.     

Cytochemical distribution of beta-glucuronidase activity in experimental brain tumors and brain tissue in vivo and in vitro

Summary Activity of beta-glucuronidase in experimental brain tumors and in nervous tissue was studied. The activity of the enzyme was detected both in gliomas and sarcomas exhibiting a high degree of anaplasia and dysplasia. Reactive glia showed high enzymatic activity; whereas activity in normal nervous tissue was absent. In tissue culture the activity of beta-glucuronidase was observed mainly in astrocytes, and its intensity expressed the degree of cellular maturation and differentiation.The investigation was carried out under a grant from PL 480 US Public Health Service Program, Agreement 05-004-1.     

Cell density-dependent stimulation of glutamine synthetase activity in cultured mouse teratoma cells

A density dependent stimulation of glutamine synthetase (GS) activity has been observed in cultures of mouse teratoma cells. GS specific activity increased as cultures approached confluency to a level greater than 2-fold over the basal level found in sparse cultures. After confluency the GS specific activity returned to the basal level found in sparse cultures. The enzyme increase could not be attributed to age of cultures, medium or glutamine depletion, cell leakage of GS, or change in the amount of cellular protein. Dibutyryl cyclic AMP (db-cAMP) plus theophylline lowered GS specific activity both in cultured teratoma and in teratoma obtained from ascites grown tumors. The enzyme increase observed in cultured teratoma cells could be prevented by cycloheximide, and enhanced by hydrocortisone or actinomycin D.