In vivo spin trapping of nitric oxide from animal tumors.

Spin trapping/electron paramagnetic resonance (EPR) spectroscopy allows specific detection of nitric oxide (NO) generation, in vivo. However, in order to detect an EPR signal in living organism, usually a stimulation of immune system with LPS is used to achieve higher than physiological NO levels. Here, we report non-invasive spin trapping of NO in tumors of non-treated, living animals. EPR spectroscopy was performed at S-band to detect NO in Cloudman S91 melanoma tumors growing in the tail of living, syngeneic hosts-DBA/2 mice. Iron (II) N-(dithiocarboxy)sarcosine Fe2+(DTCS)(2) was used as the spin trap. The results were confirmed by X-band ex vivo study. A characteristic three-line spectrum of NO-Fe(DTCS)(2) (A(N)=13 G) was observed (n=4, out of total n=6) in non-treated tumors and in tumors of animals treated with l-arginine. Substrate availability did not limit the detection of NO by spin trapping. Half-life time of the NO-Fe(DTCS)(2) in tumor tissue was about 60 min. The feasibility of non-invasive spin trapping/EPR spectroscopic detection of NO generated in tumor tissue in living animals, without additional activation of the immune system, was demonstrated for the first time.     

Comparison of Iloprost, Cicaprost and prostacyclin effects on cyclic AMP metabolism in intact platelets.

We have compared the effects of prostacyclin (PGI2) and its stable analogs, Iloprost and Cicaprost, on cyclic AMP metabolism in intact platelets. All three compounds show similar but not identical patterns of prostaglandin concentration-dependent cyclic AMP formation. All three compounds apparently stimulate and inhibit cyclic AMP formation with different concentration dependencies, indicating the presence of distinct stimulatory and inhibitory receptors. Differences in response can be accounted for by slight differences in affinity of stimulatory and inhibitory receptors for the prostaglandins, by the fact that Iloprost contains almost 50% of a relatively inactive isomer, and by the fact that PGI2 is labile in aqueous solution, with a half-life on the order of a few minutes. We conclude 1) stimulation and inhibition of adenylate cyclase is not due to separate effects of 16S- and 16R-stereoisomers of Iloprost because similar patterns were obtained with a single isomeric form of Cicaprost and with authentic PGI2; 2) prostaglandin induced inhibition of adenylate cyclase is readily reversible because inhibition disappears when PGI2 concentration decays below saturation of the inhibitory receptor; 3) the potency of prostaglandins in stimulating platelet adenylate cyclase must be viewed in terms of their effects on both stimulatory and inhibitory receptors.     

Recent results in animal models of pancreatic carcinoma: histogenesis of tumors.

Animal models of carcinoma of the pancreas provide new information regarding the pathways for histogenesis of the tumors. Four models, induced by chemical carcinogens or transgenic methods, are reviewed briefly from this perspective. Recent reports indicate that carcinomas with a ductal phenotype can arise from transformed acinar cells in rodents. A transgenic mouse model provides evidence that anaplastic carcinomas and islet cell tumors may arise from primitive cells that express the elastase gene, yet retain the potential to differentiate as islet cells. In a nitrosamine-induced hamster model, ductal carcinomas appear to arise directly from ductal cells. Carcinomas in this model contained mutations in the c-K-ras oncogene that are similar to those reported in about 75 percent of human pancreatic carcinomas, whereas acinar cell carcinomas of rats lacked this mutation. The histologic type of a carcinoma may reflect the cell of origin, but this statement is not always true. Therefore, classification of tumors on the basis of phenotype rather than on the presumed cell of origin is recommended. Among the animal models, the carcinomas in hamster pancreas rank as most similar to human pancreatic ductal adenocarcinomas in regard to the phenotype of the tumors and the prevalence of the c-K-ras mutation.     

Cyclic nucleotides of human and animal glial tumors

Studies on the level of cyclic nucleotides (cAMP and cGMP) in human and animal glial tumours showed that the content of both nucleotides, especially that of cAMP, decreases in all the tumours. The cAMP/cGMP ratio also drops down. Concurrently it appears to be the most consistent parameter of nucleotide metabolism both in brain tissue and in human or animal glial tumours. The growing tumour affects cAMP and cGMP metabolism not only in the involved but also in the other hemisphere. No principal differences between human and animal tumours have been revealed in the content of cyclic nucleotides and its variation in tumour tissue.     

PolyIC GE11 polyplex inhibits EGFR-overexpressing tumors

Phage display has identified the dodecapeptide YHWYGYTPQNVI (GE11) as a ligand that binds to the epidermal growth factor receptor (EGFR) but does not activate the receptor. Here, we compare the EGFR binding affinities of GE11, EGF, and their polyethyleneimine-polyethyleneglycol (PEI-PEG) conjugates. We found that although GE11 by itself does not exhibit measurable affinity to the EGFR, tethering it to PEI-PEG increases its affinity markedly, and complex formation with polyinosine/cytosine (polyIC) further enhances the affinity to the submicromolar range. PolyIC/PPGE11 has a similar strong antitumor effect against EGFR overexpressing tumors in vitro and in vivo, as polyIC/polyethyleneimine-polyetheleneglycol-EGF (polyIC/PP-EGF). Absence of EGFR activation, as previously shown by us and easier production of GE11 and GE11 conjugates, confer polyIC/PPGE11 a significant advantage over similar EGF-based polyplexes as a potential therapy of EGFR overexpressing tumors.     

Transfection of macrophage inflammatory protein 1 alpha into B16 F10 melanoma cells inhibits growth of pulmonary metastases but not subcutaneous tumors

Macrophage inflammatory protein 1 alpha (MIP-1 alpha), a CC chemokine, is a chemoattractant for T cells and immature dendritic cells. Plasmacytoma cells expressing MIP-1 alpha generate a cytotoxic T cell response without affecting tumor growth. To understand this discrepancy, we compared a local tumor model with a metastatic one using MIP-1 alpha-transfected B16 F10 melanoma cells. Clonal idiosyncrasies were controlled by selecting three lipotransfected tumor clones and two pcDNA vector transfected control clones with equivalent in vitro proliferative capacities. No significant differences were seen between the MIP-1 alpha-producing and control melanoma cells after s.c. injection in the hind leg. All animals had a leg diameter of 10 cm in 18.5-21.5 days. However, after i.v. injection the number of pulmonary foci was significantly reduced in the MIP-1 alpha-producing clones. Injection of 10(6) control transfected cells resulted in a median of 98.5 tumor foci in 2 wk, whereas the injection of the MIP-1 alpha-producing clones resulted in 89.5, 26.5, and 0 foci. The number of metastatic foci was inversely proportional to the amount of MIP-1 alpha produced by the clone in vitro. Flow cytometry showed a significant increase in CD8(+) cells in lungs of mice with MIP-1 alpha-transfected tumors 3 days after injection. This increase was not maintained 10 days later despite continued production of MIP-1 alpha. The protection offered by transfection with MIP-1 alpha was significantly impaired in beta(2)-microglobulin(-/-) mice. Our findings suggest that MIP-1 alpha is effective in preventing the initiation of metastasis, but not at sustaining an effective antitumor response.     

A morphometric comparison of subcellular structures between primary breast tumors and their nodal metastases.

A morphometric study of subcellular structures in human primary breast tumors (of the ductal infiltrating type) and their synchronous lymph node metastases was carried out using planimetry and stereology. Each primary neoplasm was compared separately with its axillary metastatic growth in order to detect differences in the quantitative estimates of their subcellular components. A set of 24 morphometric parameters was used to quantitatively describe each neoplastic cell profile. Although some subcellular parameters showed significant differences between the cells of a primary tumor and its metastases, no parameter was found to be consistently altered in all cases. No consistent increase or decrease in the values of the affected parameters was observed in the metastases. More than being due to the expression of a biologically variant (more-or-less differentiated) metastatic phenotype, the differences in stereologic parameters detected in metastatic cells appear to reflect the existence of different functional states of the same cell type.     

Immunochemical identification of beta2-globulin in metastases of ovarian tumors

Antisera were obtained upon immunization of rabbits with the extracts obtained from metastatic tissues of primary ovarian carcinoma into the omentum. Eight antigens were found, which were termed "ovarian-metastatic antigens" (OMA). OMA 1-7 showed cross-reactions with the antigens of one of the normal organs of the adult man: kidneys, spleen, brain. OMA-8 was not identified in the internal organ tissues of the adults and fetuses. Using immunodiffusion method, OMA-8 was revealed in the tissues of metastases of primary ovarian cancer into the omentum in 55% of cases (3-180 mg/l), in 50% of cases it was detected in primary ovarian carcinomas (3-50 mg/l) and in mature placenta (38-40 weeks) (6-12 mg/l). OMA-8 was detected in the chorion (8-20 weeks) and in the amniotic fluid at all periods at the maximum sensitivity of immunodiffusion method (1-2 mg/l). OMA-8 is a beta 2-globulin of protein nature with NW 35 kD, containing alpha- and beta-subunits with MW 18 and 19.5 kD. No carbohydrates, lipids and ferrum were determined in OMA-8. Its physico-chemical and antigenic properties differ from those of the described carcinoembryonic and placental proteins.     

Calmodulin inhibits entry of Bordetella pertussis adenylate cyclase into animal cells

Bordetella pertussis, the pathogen responsible for whooping cough, releases a soluble calmodulin-sensitive adenylate cyclase into its culture medium. Recently, Confer and Eaton [Confer, D., & Eaton, J. (1982) Science (Washington, D.C.) 217, 948-950], as well as Hanski and Farfel [Hanski, E., & Farfel, Z. (1985) J. Biol. Chem. 290, 5526-5536], have shown that crude extracts from B. pertussis containing adenylate cyclase activity cause elevations in intracellular cAMP when incubated with human neutrophils or lymphocytes. These investigators proposed that the bacterial enzyme enters animal cells and catalyzes the formation of cAMP from intracellular ATP. In this study, B. pertussis adenylate cyclase was purified to remove contaminating islet activating protein and examined for its effects on intracellular cAMP levels of human erythrocytes and N1E-115 mouse neuroblastoma cells. In both cases, the enzyme catalyzed the formation of intracellular cAMP. Addition of calmodulin to the adenylate cyclase preparations completely inhibited formation of intracellular cAMP catalyzed by the bacterial enzyme, indicating that cAMP was not synthesized extracellularly and then taken up by the cells. These experiments illustrate that the bacterial enzyme does enter animal cells and that the enzyme-calmodulin complex does not.     

Plasma membrane-associated cysteine proteinases in human and animal tumors

The ability of tumor cells to invade into and through normal tissue during the metastatic cascade has been attributed to tumor-associated degradative enzymes including proteinases of the metallo, serine and cysteine classes. Work from several laboratories has established that the cysteine proteinases cathepsins L and B are released from tumor cells, primarily as latent precursor forms. In addition, a cathepsin B-like cysteine proteinase has been shown to be associated with the plasma membrane fraction of several animal and human tumors. This form of the enzyme retains activity under physiologic (or pathologic) conditions including at neutral pH and in the presence of low Mr inhibitors. Since we have established that cathepsin B can degrade the basement membrane attachment glycoprotein laminin, we speculate that plasma membrane-associated cathepsin B may participate in focal dissolution of the basement membrane during tumor cell extravasation.     

A matter of the heart: myocardial metastases in neuroendocrine tumors

The aim of the present study was to evaluate frequency, clinical spectrum, and treatment of myocardial metastases in patients with histologically proven neuroendocrine tumors by analysis of our database and literature review. The literature on cardiac metastases in patients with neuroendocrine tumors published from 1973 to the present was reviewed for age, sex, primary tumor localization, metastases, symptoms, complications, treatment, diagnostic methods, and histology. Patient records from our institution were analyzed retrospectively for cardiac metastases detected by any diagnostic means and detailed patient histories are given. 4 patients with myocardial metastases could be identified in our database (n=550) while literature review identified 41 published cases. Mean age at initial diagnosis was 57.5 years (females=13, males=28), primary tumor localizations were foregut (n=7), midgut (n=28), hindgut (n=1), or unknown (n=3). Carcinoid syndrome was reported for 28 patients. Cardiac involvement was right-ventricular only (n=10), left-ventricular only (n=11), or biventricular (n=10). Diagnosis was obtained by echocardiography (n=21), CT/MRI (n=12) and other methods (n=9), or by autopsy (n=9). We describe visualization of cardiac metastases by (68)Ga-DOTATOC-PET/CT for the first time. Clinical presentation ranged from asymptomatic patients to cardiac arrest. Follow-up times ranged from <1 month up to 12 years. Clinicians treating patients with neuroendocrine tumors should be aware of the heart as a possible site of metastatic disease. Echocardiography and MRI are the methods of choice for follow-up, while PET/CT might contribute to earlier and more frequent detection. Management of cardiac metastases requires close cooperation between specialists of internal medicine, nuclear medicine, and cardiac surgery.     

Antimetabolic activity of L-ascorbic acid in human and animal tumors

1. The effect of high concentrations of L-ascorbic acid on the growth of some human and animal transformed and non-transformed cell lines has been investigated. Directly implemented into culture of transformed cell lines it decreased [3H]thymidine, [3H]uridine and [3H]leucine incorporation into cells. Vitamin C inhibited DNA synthesis by transformed cells 3-4 times more efficiently than by normal cells. 2. In vivo treatment of athymic nude mice bearing human mammary carcinoma with 500 mg/kg L-ascorbic acid for the first 15 days markedly inhibited the growth of tumor cells. 3. As determined by alkaline elution, both DNA strand breaks and DNA cross links were observed in mammary carcinoma cells treated with vitamin C. DNA-DNA and DNA-protein cross links in cells treated with L-ascorbic acid were revealed by the proteinase K assay. Removal of vitamin C caused an immediate onset of spontaneous repair of single or double stranded DNA breaks. If, however, vitamin was reintroduced into cell culture, this spontaneous repair was reversed. 4. Our results indicate an antimetabolic activity of L-ascorbic acid in human and animal transformed cells, probably due to lethal damages in DNA.     

An animal model for tumors of the large intestine]

Dimethylhydrazine (DMH) and its derivatives induced in many animal species tumors of the large intestine with a great specificity and reproductibility. Oour personal observations using rats BD IX injected weekly with DMH are summarized in this presentation. The induced tumors appear as invaded tumors already at the microscopic stade. Their growth is best described by a Gompertz function. The number of induced tumors increases with time as a non linear function. This model is very useful for the study of the biology of human tumors with a low development.