Arginine metabolic pathways involved in the modulation of tumor-induced angiogenesis by macrophages.

Neovascularization, an essential step for tumor progression and metastasis development, can be modulated by the presence of macrophages (Mps) in the tumor microenvironment. The ability of Mps to regulate the angiogenicity of the LMM3 tumor cell line was studied. Peritoneal Mps from LMM3 tumor-bearing mice (TMps) potentiate in vivo LMM3 angiogenicity. These results were confirmed by CD31 immunoblotting assays. The activity of TMps depended on nitric oxide synthase (NOS) and arginase (A) activity. By immunoblotting we evidenced that AI and AII isoforms were up-regulated in TMps while the inducible and neuronal NOS isoforms were highly expressed in normal Mps. TMps might positively modulate tumor growth by stimulating angiogenic cascade mainly through polyamine synthesis.

Treatment strategies for early-stage chronic lymphocytic leukemia: can interferon-inducible MxA protein and tumor necrosis factor play a role as predictive markers for response to interferon therapy?

The potential benefit of interferon (IFN)-alpha therapy in early-stage B cell chronic lymphocytic leukemia (B-CLL) patients is still under discussion, and no assays are available to distinguish potential responders from nonresponders. Herein we analyzed the usefulness of serum tumor necrosis factor (TNF, a cytokine released by CLL cells) and MxA protein (an intracellular marker for biologic activity of endogenous IFN) concentrations as predictive measurements for evolution and response to IFN therapy in early-stage CLL patients. TNF levels and MxA expression were determined at diagnosis in 21 CLL patients. A statistically significant correlation was found between low TNF levels and MxA expression and between high TNF levels and no measurable MxA expression. The patients were then randomized to receive IFN-alpha or no therapy and were evaluated for response and evolution. When response to IFN-alpha therapy was considered, it became apparent that early-stage CLL patients with higher TNF levels and no measurable MxA expression were more likely to benefit from IFN therapy, whereas those patients with lower TNF levels and MxA expression could be considered CLL candidates for longer survival without therapy. More patients have to be tested to strengthen the value of MxA expression and TNF concentrations for subsequent response to IFN-alpha therapy.

Hydrogen peroxide is involved in lymphocyte activation mechanisms to induce angiogenesis.

T-lymphocytes from tumour-bearing mice are able to trigger the angiogenic cascade. Since it is known that tumour growth produces reactive oxygen species (ROS), the aim of this study was to evaluate the role of hydrogen peroxide (H2O2) on the activation of lymphocytes and their induction of this vascular response. Studies on lymphocytes, stimulated in vitro by ROS to induce angiogenesis, showed that only the enzyme catalase (CAT) could block the activation. The incubation of normal lymphocytes with H2O2 stimulated these cells to induce angiogenesis. The administration of H2O2 or an oxidative stress-producing drug (doxorubicin) to normal mice activated in vivo angiogenesis. In tumour-bearing mice, high levels of lipid peroxidation products were observed in the spleen, but not in the liver or kidney. Moreover, when the ROS scavenger enzyme activities (superoxide dismutase (SDM) and CAT) were determined, we observed low CAT activity in normal spleens, reflected in a high SDM/CAT ratio, when compared to liver or kidney values. We also showed an increasing value of the SDM/CAT ratio with tumour growth. These results strongly suggest that H2O2 could be involved in the mechanisms of lymphocyte activation and their induction of angiogenesis during tumour growth.

Polyamines prevent DFMO-mediated inhibition of angiogenesis.

Tumor growth mainly depend on formation of new blood vessels. DFMO (alpha-difluoromethylornithine), an inhibitor of polyamine biosynthesis, inhibits tumor growth in many animal tumors. Our investigation was to evaluate the requirement of polyamines for induction of angiogenesis by tumor cells and spleen lymphocytes from tumor-bearing mice. In this regard, we have added DFMO to cell cultures. The neovascular response induced either by tumor cells or spleen lymphocytes was completely abrogated. This inhibition could be reversed by the addition of exogenous putrescine. These findings suggest that the effect of DFMO on angiogenesis is, in part, mediated by the inhibition of polyamine biosynthesis.

Heparin receptors in two murine mammary adenocarcinomas with different metastatic ability: relationship with growth inhibition.

Binding of heparin to primary cultured cells of two murine mammary adenocarcinomas with low (M3) and high (MM3) lung, metastatic capacity was determined. Heparin binding was rapid, specific and saturable. MM3 cells grown for 24 h in fetal calf serum (FCS)-free medium exhibited a higher number of binding sites for 3H-heparin [(11 +/- 1) x 10(5) sites per cell than M3 cells [(6.9 +/- 0.6) x 10(5) sites per cell]. However, when M3 cells were grown in the presence of 2% FCS, they showed less heparin binding sites [(3.5 +/- 0.4) x 10(5) sites per cell]. In contrast, dissociation constants were very similar for MM3 and M3 cells grown with or without FCS (Kd = 2-4 x 10(-9) M). Furthermore, heparin inhibited MM3 and M3 cell growth both in the absence or presence of FCS. Competition studies showed that chemically modified heparins lacking antiproliferative effect (O-desulfated; O/N-desulfated N-acetylated and N-desulfated heparins) were not able to inhibit 3H-heparin binding. N-desulfated N-acetylated heparin, which had partial antiproliferative effect, partially inhibited 3H-heparin binding, while heparin with a high antiproliferative activity inhibited more than 90% 3H-heparin binding. The antiproliferative effect of heparin and chemically modified heparins seems to be related to their binding ability to the cell membrane.

Characterization of a fibroblastoid mammary carcinoma cell line (LM2) originated from a mouse adenocarcinoma.

We established and characterized a new mammary tumor cell line, LM2, derived from M2 mammary adenocarcinoma which spontaneously appeared in a BALB/c female mouse. The LM2 cell line has been maintained in culture for more than 40 passages and grows as poorly differentiated elongated cells. Ultrastructural and immunocytochemistry analysis revealed characteristic features of adenocarcinoma. Cytogenetic studies showed that LM2 cells are fundamentally hypotetraploid. They express metalloproteinases (MMP) and show high levels of plasminogen activator type urokinase (uPA). They were sensitive to nitric oxide (NO)-mediated cytotoxicity when NO derived from an exogenous donor. In vivo, although LM2 cells were able to grow in the lungs, they could not metastasize to the same target organ from s.c. primary tumors. The LM2 mouse mammary adenocarcinoma cell line is a suitable model to examine different aspects of tumor biology, in particular those related to the different pathways involved in the metastatic cascade and in the cytotoxicity mediated by NO.

The antioxidant enzymatic blood profile in Alzheimer's and vascular diseases. Their association and a possible assay to differentiate demented subjects and controls.

A study of several elements of the antioxidative system: Cu-Zn superoxide dismutase (SOD), catalase (CAT), glutathione system (GLU), chemiluminescence (CHE), and antioxidant capacity (AOX), was conducted in 20 demented probable Alzheimer's (DAT), and 15 vascular demented (VD) patients, 19 control (C) subjects, and 11 relatives (F) of one DAT patient. A significant association was found between the variables of the antioxidant system, measured in blood samples, and the neurological pathologies VD and DAT: Kruskal-Wallis test; p = 0.0006 (p = 0.014 when the analysis did not include SOD). This demonstrated that VD and DAT diseases are accompanied by oxidative disorders. The VD and DAT diseases are differentially distinguishable by changes in blood profiles. A graphical method for classification, the Principal Components Analysis (PCA), distinguished between demented and non-demented subjects on the basis of their laboratory variables. A numerical method, Discriminant Functions (DF), constructed to separate the clinical groups on the basis of the same variables, obtained relatively high percentages of success: 92% of demented were detected against healthy subjects; of the latter 82% have been correctly identified as non-demented. Discrimination between VD and DAT patients was achieved for 100% of VD and 86% of DAT patients. DF were similarly successful in detecting the healthy condition of DAT relatives. Possible different mechanisms involved in H2O2 elimination in DAT and VD patients are proposed, where CAT is the responsible enzyme of this reaction in DAT patients, while in VD this function would be achieved mainly through the action of GLU. It seems that SOD levels are stable, at least, within one year. Variations appear to be linked with clinical changes.

Soluble factors from the target organ enhance tumor cell angiogenesis: role of laminin SIKVAV sequence.

The ability of tumor cells to respond to microenvironmental factors present in the target organ determines in part the successful development of a metastasis. In a previous work it was demonstrated that the conditioned medium (CM) from lungs of normal mice stimulates in vitro migration, proliferation and uPA activity of cells from a murine mammary adenocarcinoma moderately metastatic to lung. This CM also enhanced local and metastatic tumor growth. Here, we show that lung CM enhanced neovascularization when inoculated together with LM3 tumor cells into the skin of syngeneic mice. A similar tumor-induced angiogenesis response was obtained when lung CM was injected systemically. Western blot analysis of lung CM revealed the presence of some laminin fragments containing the sequence SIKVAV. To determine whether those molecules were responsible for the observed angiogenic effects, the CM was depleted of the peptides containing the SIKVAV sequence. We observed that the SIKVAV-depleted lung CM lost its ability to induce an enhancement of the tumor neovascular response. Our results suggest a role for the target organ in facilitating the neovascularization of tumor cells, probably through the participation of active peptides derived from the proteolytic degradation of the basement membrane component laminin.

[Free radicals of oxygen and superoxide dismutase. Biological and medical aspects]. / Radicales libres de oxígeno y superóxido dismutasas. Aspectos biológicos y médicos.

Oxygen free radicals (OFR) are very reactive and unstable metabolites capable of altering important biomolecules including proteins, lipids and nucleic acids. OFR are regulated by enzymes such as superoxide dismutases (SOD), catalase, glutation peroxidase and by molecules such as vitamins E, A, C, and K, selenio, cystein and other compounds. Increased OFR levels due to an overproduction of these metabolites or to a failure in the control system, induce cellular and tissue injuries that could lead to diseases such as atherosclerosis, arthritis, fibrosis, lung and heart injuries, neurological disorders and cancer. In this article we consider the use of SOD as therapeutic agents both in human and experimental models. We also refer to the administration of SOD as a protective factor against secondary injuries during radiotherapy and to the determination of SOD as a tumor marker.

[Nervous cells transplantation in neurodegenerative diseases]. / Trasplante de células nerviosas en enfermedades neurodegenerativas.

This article is a bibliographic review concerning the scientific advances in nervous tissue transplantation in experimental animals and in humans as applied to neurodegenerative diseases, particularly Parkinson's disease. Data show the possibility that the transplantation of nervous tissue may alleviate the typical symptoms of some of these diseases. Since the first trials in 1890, there has been a remarkable progress in this field, encouraging the idea that nervous tissue transplantation may be considered in clinical practice.

[Olfactory mucosa: a continuous source of neurons]. / La mucosa olfatoria: una fuente permanente de neuronas.

Experimental transplantation of embryonic nervous cells in the central nervous system demonstrates that these precursor cells can be used to repair damaged cells in neurodegenerative diseases. However, the use of cells from embryos is still controversial and alternative ethically accepted sources are needed to overcome the inherent problems. Several sources have been proposed such as bone marrow cells, olfactory bulb cells and astrocytes. We suggest the use of neuronal precursor cells from the nasal olfactory mucosa as an alternative source for transplantation therapy, since these peripheric cells exhibit stem cell characteristics.

Mast cell kinetics during tumor growth.

The behavior of mast cells was studied during tumor growth. Sarcoma 13, and normal syngeneic kidney, as control, were implanted subcutaneously in BALBc mice. The number of mast cells in the hypodermis and peritumoral tissue increased 3-fold, 20 days after implantation. In the peritumoral tissue, mast cell degranulation increased together with tumor growth, while in the dermis and hypodermis, it first decreased and only became evident on day 20. Mitosis and mast cell degranulation, more conspicuous in tissues near the tumor, seem to indicate the existence of tumoral factors which spread slowly from the tumor to distant zones. The role of mast cells in peritumoral tissues will be evaluated in the near future.

Influence of mast cells on two murine mammary adenocarcinomas.

A high content of mast cells (MC) is considered characteristic of neoplasias. Some researchers postulate MC as enhancers of tumor development, others as inhibitors. The purpose of this study was to evaluate the ability of peritoneal cavity MC to modulate the in vivo and in vitro growth of two murine mammary adenocarcinomas with low (M3) and high (MM3) metastatic capacity. MC from the peritoneal cavity of normal (NMC) or tumor-bearing mice (TMC) were used. TMC, which by histochemical methods appeared degranulated, were not able to modify the tumorigenicity of both tumors. NMC, in contrast, decreased M3 tumor incidence and cell proliferation in vitro and increased the latency period of only MM3 tumors. No changes in the number of spontaneous lung metastases could be seen in experiments carried out either with NMC or TMC. We conclude that NMC, which are rich in chemical mediators, can modulate some of the first steps of tumor development. Once tumor-mediated degranulation occurs, MC become unable to regulate it.

Angiogenic activity by spleen cell supernatants from tumor-bearing and tumor-resected mice.

Supernatants of cultured spleen cells (SCS) from small tumor-bearing mice (STBM) and large tumor-bearing mice (LTBM) are able to enhance tumor growth as well as accelerate tumor takes in vivo when inoculated 24 h before tumor implant. After tumor resection enhancing activity disappears at a rate depending on the size of the resected tumor. Spleen cells from tumor-bearing mice also evoke a complex vascular response, lymphocyte-induced angiogenesis (LIA) elicited via the release of lymphokines from activated T cells. As angiogenic factors promote tumor development we investigated if SCS from tumor-bearing and tumor-resected mice contain factors capable of evoking a LIA response. Angiogenic activity was detected by SCS of small and large tumor-bearing mice as well as in large tumor-resected mice. On the other hand, SCS from small tumor-resected mice are not able to evoke an angiogenic response. Possibly, the large antigenic burden in LTRM stimulate the immune system in a different way than in STRM. We can suggest that the different behavior of spleen cells after small and large tumor removal can be explained by quantitative or qualitative changes in the spleen subpopulations.