The antimetastatic drug NAMI-A potentiates the phenylephrine-induced contraction of aortic smooth muscle cells and induces a transient increase in systolic blood pressure.

The ruthenium-based drug imidazolium trans-imidazoledimethylsulphoxidetetrachlorido ruthenate (NAMI-A) is a novel antitumour drug under clinical evaluation. In this study, NAMI-A is tested on aortic rings in vitro and on the systolic blood pressure in vivo with the aim of evaluating its effects on smooth muscle cells and, more in general, on the vascular system. Pre-incubation of aortic rings with 10 µM NAMI-A for 10 min potentiates the contraction induced by phenylephrine (PE). The reduction of the B max value of [(3)H]-prazosin bound to NAMI-A-treated aortic rings and the ability of NAMI-A to displace [(3)H]-prazosin and [(3)H]-IP3 binding by 25 and 42%, respectively, suggest the involvement of α1-adrenoceptor in mediating the effects on smooth muscle cells. NAMI-A also decreases the number of maximal sites of [(3)H]-prazosin bound to kidney membrane preparation from 34 to 24 fmol/mg proteins. A single i.p. dose (105 mg/kg) or a repeated treatment for 6 consecutive days (17 mg/kg/day) in Wistar rats increases the systolic blood pressure, respectively, 1 h and 3 days after treatment, and the responsiveness of rat aortic rings to PE. Atomic absorption spectroscopy confirms the presence of ruthenium in the aortic rings excised from the treated rats. These findings suggest monitoring the cardiovascular parameters when the drug is used in humans for treating cancer patients, particularly if the drug is associated with chemicals that are potentially active at the cardiovascular level.

Infrared microspectroscopy of live cells in microfluidic devices (MD-IRMS): toward a powerful label-free cell-based assay.

Until nowadays most infrared microspectroscopy (IRMS) experiments on biological specimens (i.e., tissues or cells) have been routinely carried out on fixed or dried samples in order to circumvent water absorption problems. In this paper, we demonstrate the possibility to widen the range of in-vitro IRMS experiments to vibrational analysis of live cellular samples, thanks to the development of novel biocompatible IR-visible transparent microfluidic devices (MD). In order to highlight the biological relevance of IRMS in MD (MD-IRMS), we performed a systematic exploration of the biochemical alterations induced by different fixation protocols, ethanol 70% and formaldehyde solution 4%, as well as air-drying on U937 leukemic monocytes by comparing their IR vibrational features with the live U937 counterpart. Both fixation and air-drying procedures affected lipid composition and order as well as protein structure at a different extent while they both induced structural alterations in nucleic acids. Therefore, only IRMS of live cells can provide reliable information on both DNA and RNA structure and on their cellular dynamic. In summary, we show that MD-IRMS of live cells is feasible, reliable, and biologically relevant to be recognized as a label-free cell-based assay.

Bacillus cereus cell and spore properties as influenced by the micro-structure of the medium.

AIM: To investigate the effect of different growth conditions on Bacillus cereus cell and spore properties. METHODS AND RESULTS: Bacillus cereus was grown on agar plates with different surface water conditions (wet and dry) or viscosity. Cell populations displayed different types of behaviour, and heterogeneity was manifested in cell motility and dimension. Spore populations were heterogeneous regarding their properties, namely size and thermal resistance. The smallest spores were produced from flagellated cells, which also displayed jet-motility, growing on the wettest agar. Cytometric analysis also revealed within the smallest spores a sub-population labelled by propidium iodide (PI), indicating that spore populations were partly damaged. Nonmotile cells grown on diffusion-limiting media were elongated and produced the least thermal-resistant spores. CONCLUSIONS: The micro-structural properties of the media were found to influence cell and spore properties. Abundant surface water enabled flagellar motility and resulted in a heterogeneous cell and spore population, the latter including small and damaged spores. High viscosity gave rise to filamentous cells and more heat-sensitive spores. SIGNIFICANCE AND IMPACT OF THE STUDY: This study provides useful information on conditions resulting in heterogeneous populations of damaged and heat-sensitive spores.

Isolation of a murine metastatic cell line and preliminary test of sensitivity to the anti-metastasis agent NAMI-A.

We have isolated a new cell line (metGM) obtained from the spontaneous lung metastases of the mouse MCa mammary carcinoma. MetGM is a stable cell line which, after one year from its isolation, grows in vitro in suspension, forming cell aggregates, with cells that show irregular blabbing borders, active protein synthesis and convoluted nuclei and which have the capacity of invading matrigel membranes on which they give rise to a network of branching colonies. The preliminary study of the effects of the anti-metastasis ruthenium complex NAMI-A on metGM showed no direct cytotoxicity, with a mild reduction of cell proliferation, independent of the concentration of the ruthenium complex and not evident before 24 hours from treatment. A 10% DNA fragmentation was also measured on metGM cells 24 hours after challenge for 1 hour with 10(-5)M NAMI-A, suggesting that this compound is probably capable of apoptosis in a metastasis-derived cell line. Besides these effects on a limited percent of the cell population, NAMI-A changed the shape of the metGM cells and these alterations might account for the non-cytotoxic anti-metastatic properties of this innovative ruthenium complex. Thus MetGM appears to be a novel cell line suitable for the in vitro study of compounds endowed with anti-metastatic properties and for the development of new drugs with this activity.

Influence of agar content on the growth parameters of Bacillus cereus.

Factors governing Bacillus cereus colony growth on agar media as modified by the agar content (1-7%, w/v) were studied. Agar had a significant effect on the radial growth rate which diminished as the agar content increased. Cell density in colonies (colony density) was found to decrease during the incubation time, with lower values occurring in the presence of 1% agar. Size and DNA content of the cells grown on 1 and 7% agar were similar. An increasing proportion of cell population growing on 7% agar produced spores during the 24-h incubation period. It was shown that 'water condition' on the agar surface could be associated with colony density, with 7% agar media presenting the thinnest nominal thickness of the liquid film. On the other hand, the partial drying phenomena of the agar media which occur during preparation and incubation, could not account for the observed differences in colony growth.

In vitro growth of TS/A adenocarcinoma and of the gene transfected TS/A-IL4 line on biological substrates.

The growth capacity and adaptation of TS/A and TS/A-IL4 lines on laminin, fibronectin, collagens I and IV and matrigel compared to plastics were studied by flow cytometry. On plastic plates, TS/A-IL4 grows in vitro more slowly than the TS/A line and shows a more differentiated phenotype. TS/A-IL4 cells loose the capacity to bind lymphocytes and peroxidase positive cells obtained from mice implanted with the same tumour. The ratio between fibroblast- and epithelial-like cells of TS/A adenocarcinoma is subjected to marked modifications depending on the substrate on which the two cell lines are grown. IL4 release per cell unit is increased by collagen I as is the number of CD54 positive cells, suggesting that, at least in part, the in vivo rejection of TS/A-IL4 tumor might be ascribed to the stimulatory effect of the tissue on the IL4 release by tumor cells. The overall result is that gene modified TS/A-IL4 line shows marked changes of behaviour, most of them depending on the substrate on which tumor cells are growing.

In vitro down regulation of ICAM-1 and E-cadherin and in vivo reduction of lung metastases of TS/A adenocarcinoma by a lysozyme derivative.

The aim of the present investigation was to examine the effects of the lysozyme derivative mPEG-lyso (hen egg-white lysozyme coupled with polyoxyethylenglycol), on TS/A adenocarcinoma cell line in vivo and in vitro. mPEG-lyso reduces the number of ICAM-1+ and E-cadherin+ cells of TS/A adenocarcinoma cell line in vitro, and causes a marked decrease of spontaneous lung metastases in vivo. In both cases, mPEG-lyso reduces the number of tumour cells in sythesis and pre-mitotic phases. In connection with the reduction of cells expressing adhesion molecules, mPEG-lyso reduces the number of infiltrating leukocytes in the primary tumour in vivo and reduces the binding capacity of splenocytes to tumour cells in vitro. These data stress, for the first time, that the in vivo control of mPEG-lyso on lung metastasis formation of solid metastasising tumours may be due to a combination of effects on tumour cells in addition to those on host's immune system.

Paracrine effects of IL-4 transfection on TS/A adenocarcinoma cells mediate reduced in vivo growth.

The in vitro/in vivo growth capacity and phenotype of TS/A and the IL4-transfected TS/A-IL4 cell lines were studied by cell cycle analysis, expression of ICAM-1/CD54, transferrin receptor/CD71 and E-cadherin and by histology of the primary tumors. TS/A-IL4, unlike the TS/A line, shows in vitro a marked increase in the fibroblastoid cell type and a decreased E-cadherin expression. Administration of conditioned medium containing IL4 obtained from the TS/A-IL4 cell line, stimulates CD54 expression in the TS/A cell line. TS/A-IL4 tumors grow more slowly in vivo and are ultimately rejected. These processes are accompanied by a marked increase in collagen and extracellular matrix proteins and increased recruitment and degranulation of mast cells. The paracrine effect of IL4, released by the transfected tumor cells, might be responsible for the reduced in vivo growth of the TS/A cell line in the presence of TS/A-IL4 cells.

Stimulation of GALT and activation of mesenteric lymph node lymphocytes by a modified lysozyme in CBA mice with MCa mammary carcinoma.

Lysozyme (hen egg-white lysozyme) and its derivative mPEG-lyso (lysozyme coupled with polyoxyethyleneglycol) were tested in CBA mice bearing MCa mammary carcinoma for their effects on intestinal mucosal immunity (GALT) and mesenteric lymph node lymphocytes (MLNL), after oral administration. Following a cycle of administration of 100 mg/kg/day lysozyme or 350 mg/kg/day mPEG-lyso for 9 consecutive days, GALT was analyzed by using optical histology, and mesenteric lymph node lymphocytes were studied by cytofluorimetric analysis of CD3, CD4 and CD8 antigens, and of DNA and RNA content following in vitro culture with concanavalin A. Both lysozymes significantly increase the number of lymphatic nodules on gut epithelium as determined by histological analysis of sections of small bowel. mPEG-lyso, unlike native lysozyme, gives protection from the decline of the blastogenic activity of MLNL observed at early stages of tumor growth, as shown by the increased nucleic acid content of these cells. On the same cells, both lysozyme and mPEG-lyso also seem to prevent the decline of CD4+ cells observed during tumor growth in control animals. These data confirm the effects of lysozyme on GALT and show that the new lysozyme derivative mPEG-lyso has effects on host immunity greater than those of the native molecule.

Antimetastatic action and lymphocyte activation by the modified lysozyme mPEG-Lyso in mice with MCa mammary carcinoma.

The effects of Lysozyme (hen egg-white lysozyme) and of its modified derivative mPEG-Lyso, (Lysozyme coupled with monomethoxypolyethylenglycol) were tested on CBA mice bearing MCa mammary carcinoma. mPEG-Lyso, given by the oral route at a dose comparable to 100 mg/kg/day of native Lysozyme, is at least as active as Lysozyme for the activation of lymphocytes obtained from different districts along the axis GALT-spleen. These effects were evidenced by measuring the in vitro response of lymphocytes of animals treated in vivo with ConA and LPS using the SRB test, and measuring the content of nucleic acids by cytofluorimetric analysis. Lymphocytes obtained from the mesenteric lymph nodes of animals treated with mPEG-Lyso, show a response to ConA and to LPS at early stages of treatment, when tumor growth reduces the response to controls. mPEG-Lyso, was also effective on lung metastasis formation. Considering that mPEG-Lyso,, compared to the native Lysozyme, completely lost its enzymatic action on Micrococcus lysodehycticus cell walls, this data suggest that the effects of lysozyme on immunity and on tumour growth are unrelated to the production of immunoactive peptidoglycans in the gut.

Cytofluorimetric analysis of gut-intraepithelial and mesenteric lymph node lymphocytes of tumour bearing mice fed with egg-white lysozyme.

The effects of the oral administration of 100 mg/kg/day egg-white lysozyme (EWL) on the expression of CD3, CD4, CD8 and CD25 antigens of lymphocytes harvested from IEL and mesenteric lymph nodes (MLNL) were tested in mice bearing MCa mammary carcinoma. Lysozyme, after oral administration, retains its enzymatic activity along the entire small bowel and almost 10% of the administered dose is recovered 1 hr after treatment in the middle of the jejunum. Correspondingly, the number of cells expressing the test antigens in MLNL is greater than in controls after a few days of treatment and is maintained high up to the end of treatment but returns to control values after treatment withdrawal; CD4:CD8 ratio is decreased by EWL in favour of CD8 positive cells. Treatment with EWL does not modify the ratio between CD4+ and CD8+ cells vs controls in IEL nor does it change the % of CD3 positive cells or the expression of IL-2 receptor at this level. These data support the existence of the induction of an immunity communication by EWL along the axis GALT-mesenteric lymph nodes which is in agreement with the reported effects of the oral administration of EWL on tumour growth in experimental systems and on host immunity in humans.

Lysozyme stimulates lymphocyte response to ConA and IL-2 and potentiates 5-fluorouracil action on advanced carcinomas.

The oral administration of 100 mg/Kg/day of hen egg-white lysozyme (Lysozyme) for 8 consecutive days to mice bearing advanced MCa mammary carcinomas and treated with 5-fluorouracil (5-FU) increases the efficacy of 5-FU on primary tumor growth and on lung metastasis formation and particularly on the postsurgical survival time. These effects are accompanied by the correction of the reduced in vitro response to ConA of lymphocytes obtained from the spleen of the treated mice. In vitro, lysozyme is capable of inducing proliferative activity in a population of blast cells, obtained by a mixed population of mononuclear cells harvested from the spleen of healthy mice, and of evoking a marked proliferative effect to IL-2 in a condition in which, in lysozyme untreated lymphocytes, IL-2 is completely uneffective. These data stress the effects of lysozyme on host immunity following oral administration and moreover indicate the beneficial role of this peptide in conditions in which the increase of host responses can significantly contribute to the success of the treatment.

Effects of prolonged treatment with decarbazine on tumor metastatic potential in mice bearing Lewis lung carcinoma.

The effects of decarbazine on tumour growth and metastatic dissemination upon treatment protracted for 10 tumour transplant generations were examined in mice bearing Lewis lung carcinoma. Primary tumour growth is unaffected by the drug, independently from the duration of the treatment. In contrast, dacarbazine significantly inhibits the formation of lung metastasis. The proportion of mice with metastasis decreases for an increasing number of transplant generations of treatment, and after 10 transplant generations of treatment metastatic capacity is completely lost in immunocompetent mice. The reduction in metastatic potential is relatively stable, being retained for three successive transplant generations without treatment. The metastatic potential of treated tumours in immunosuppressed mice is substantially similar to that in immunocompetent hosts, indicating that chemical xenogenization of tumour cells does not occur as reported for transplantable mouse leukaemias. The results obtained using clonally selected tumour lines with different metastatic potential rule out the selection by dacarbazine of tumour cell sublines with reduced metastatic potential as the mechanism of the drug's action. Upon prolonged treatment, dacarbazine appears to cause a rather stable and dramatic loss in metastatic potential, not accompanied by resistance, which might be attributed to genotypic alteration(s) of tumour cells, and which might participate into the clinical effects of the drug.

Effects of ruthenium complexes on experimental tumors: irrelevance of cytotoxicity for metastasis inhibition.

A series of 18 ruthenium(III) complexes, structurally related to the selective antimetastatic drug Na[trans-RuCl4(DMSO)Im], and characterized by the presence of sulfoxide and nitrogen-donor ligands were tested on TLX5 lymphoma and some of them on MCa mammary carcinoma to evaluate the dependence of the degree of cytotoxicity and of antimetastatic activity on the chemical properties. In vitro cytotoxicity is present only at high concentrations (> 10(-4) M), depends upon lipophilicity and is markedly affected by the presence of 5% serum or plasma samples in the culture medium. The comparison of the effects on in vitro cytotoxicity with in vivo antitumor and antimetastatic action points out that these compounds reduce metastasis formation by a mechanism unrelated to a direct tumor cell cytotoxicity. If on one hand Na[trans-RuCl4(TMSO)Iq], the compound that shows the most potent in vitro cytotoxic effects, is the least effective against metastases, on the other Na[trans-RuCl4(DMSO)Im], the compound that better reduces metastasis formation, is rather devoid of cytotoxic effects on tumor cells kept in vitro. In particular, Na[trans-RuCl4(DMSO)Im] seems to distinguish between artificially induced metastases and spontaneous metastases and reduces only the former by a cytotoxic mechanism. Out of all the tested compounds, with the exception of Na[trans-RuCl4(DMSO)Ox], Na[trans-RuCl4(DMSO)Im] is confirmed to be the most selective antimetastatic agent of the group.

Efficacy of 5-FU Combined to Na[trans-RuCl(4)(DMSO)Im], A Novel Selective Antimetastatic Agent, on the Survival Time of Mice With P388 Leukemia, P388/DDP subline and MCa Mammary Carcinoma.

The combinational treatment between the selective antimetastatic agent, sodium-trans-rutheniumtetrachloridedimethylsulfoxideimidazole, Na[trans-RuCl(4)(DMSO)Im], and the cytotoxic drug 5-fluorouracil (5-FU) on primary tumor growth and on the survival time of experimental tumors results in an effect significantly greater than that of each single agent used alone either with the solid metastasizing MCa mammary carcinoma of the CBA mouse or with the lymphocytic leukemia P388 and its platinum resistant P388/DDP subline. Thus the inorganic compound Na[trans-RuCl(4)(DMSO)Im], known for its potent and selective antimetastatic effects, positively interacts with the antitumor action of an organic anticancer agent such as 5-FU on both a solid metastasizing tumor and a tumor of lymphoproliferative type. In particular, the effects of the combinational treatment on the survival time of tumor bearing mice seem to be related to the selective antimetastatic activity of the ruthenium complex that joins the potent cytotoxicity of 5-FU for the tumor. Moreover, these data show that Na[trans-RuCl(4)(DMSO)Im] is almost as effective on the subline of P388 made resistant to cisplatin as it was on the parental line.

Antimetastatic action and toxicity on healthy tissues of Na[trans-RuCl4(DMSO)Im] in the mouse.

The ruthenium-dimethylsulfoxide complex Na(trans-RuCl4(DMSO)Im] was given i.v. to mice bearing MCa mammary carcinoma and its effects on tumor growth and on healthy host tissues were studied by macroscopic examination of primary tumor growth, by survival time, and by histological analysis using light microscopy and SEM. Either by means of vivo-vivo bioassays or by microscopic examination it appeared that the growth of lung tumors was markedly reduced, whereas the growth of the i.m. primary tumor was much less affected. These effects account for the prolongation of survival time and for the cure rate observed. The favourable effect on survival time was also influenced by the lack of significant cytotoxicity for normal tissues such as lung and kidney epithelia, muscle and liver cells, splenocytes and bone marrow. It thus appears that the selective interaction with tumor cells in the lungs cannot simply be attributed to a selectively higher localization of the compound at this site, nor to a modification of the histological structure of primary tumor. These results highlight the pharmacologic properties of this compound for the control of solid tumor metastases, an effect that was shown to be similarly exerted on advanced tumor metastases.

Water-Soluble Ruthenium(III)-Dimethyl Sulfoxide Complexes: Chemical Behaviour and Pharmaceutical Properties.

In this paper we report a review of the results obtained in the last few years by our group in the development of ruthenium(III) complexes characterized by the presence of sulfoxide ligands and endowed with antitumor properties. In particular, we will focus on ruthenates of general formula Na[trans-RuCl(4)(R(1)R(2)SO)(L)], where R(1)R(2)SO = dimethylsulfoxide (DMSO) or tetramethylenesulfoxide (TMSO) and L = nitrogen donor ligand. The chemical behavior of these complexes has been studied by means of spectroscopic techniques both in slightly acidic distilled water and in phosphate buffered solution at physiological pH. The influence of biological reductants on the chemical behavior is also described. The antitumor properties have been investigated on a number of experimental tumors. Out of the effects observed, notheworthy appears the capability of the tested ruthenates to control the metastatic dissemination of solid metastasizing tumors. The analysis of the antimetastatic action, made in particular on the MCa mammary carcinoma of CBA mouse, has demonstrated a therapeutic value for these complexes which are able to significantly prolong the survival time of the treated animals. The antimetastatic effect is not attributable to a specific cytotoxicity for metastatic tumor cells although in vitro experiments on pBR322 double stranded DNA has shown that the test ruthenates bind to the macromolecule, causing breaks corresponding to almost all bases, except than thymine, and are able to cause interstrand bonds, depending on the nature of the complex being tested, some of which results active as cisplatin itself.

Effects of L-(adamant-2-yl)glycyl-L-alanyl-d-isoglutamine on the antitumor action of cyclophosphamide, 5-fu, Cisplatin and dacarbazine on advanced carcinomas of the mouse.

A new biological response modifier, L-(adamant-2-yl)glycyl-L-alanyl-D-isoglutamine hydrochloride (AdTP), recently synthesized and characterized for antitumor, antiviral and immunomodulating properties was studied in comparison to the peptidoglycan monomer (PGM) isolated from Brevibacterium divaricatum to test the effects of their use concomitant to that of anticancer cytotoxic drugs such as cyclophosphamide, 5-fluorouracil (5-FU), cisplatin and 4-(3,3-dimethyl-1-triazeno)-5-carboxamide (dacarbazine). The experiments, performed using both Lewis lung carcinoma and MCa mammary carcinoma of CBA mouse, indicated that: a) the cytotoxic drugs, used at the maximum tolerated doses, caused different degrees of reduction of the tumors; b) the same drugs reduced lung metastases with greater efficacy when treatments were applied at the early stages of metastasis formation; c) AdTP, similarly to PGM confirmed its ability to increase some immunological parameters of lymphocytes obtained from the spleens of the treated mice; d) AdTP increased the effects of 5-FU on lung metastases but failed to show any increase of life expectancy with any treatment performed. These data indicate that AdTP, although increasing some functional responses of lymphocytes in vitro, does not improve the therapeutic activity of cyclophosphamide, cisplatin, 5-FU and dacarbazine in the experimental models presently used.

Lysozyme induced recovery of the response to cona on mononuclear-cells harvested from mice bearing mca mammary-carcinoma.

The effects of lysozyme (hen egg-white lysozyme) on lymphocytes harvested from mice bearing MCa mammary carcinoma were tested at the daily dose of 100 mg/kg given orally for 10 consecutive days. With this experimental paradigm that consists of a significant reduction of lung metastasis formation, lysozyme was seen to be capable of stimulating the recovery of the response to ConA of mononuclear cells, reduced by tumor growth; this effect was particularly evident with splenocytes and GALT lymphocytes. The effects of lysozyme depended: (i) on the presence of plastic adherent cells, (ii) at least in in vitro experiments, on the amount of lysozyme used, being higher at the dose of 250 mug/ml of incubation mixture, and (iii) on the time of challenge with lysozyme. These effects were shown either by measuring the [H-3]-thymidine incorporation into DNA or by application of the sulphorhodamine test for protein synthesis. After in vivo treatment, lysozyme significantly modified the histological architecture of the mucosal immunity of the gut, by causing a significant reduction of the number of the lymphatic nodules placed immediately under the layer of epithelial cells of villi. At the same time no significant modification of Peyer's patches was noted. Together these data stress the role of lysozyme in the modulation of host immunity and, in particular, point out the relevance of the mucosal immunity of the gut as first target for lysozyme activity.

Effects of some ruthenium chelates on MCa mammary carcinoma and on TLX5 lymphoma in mice.

A group of four Ruthenium chelates of the mixed hard/soft N-S donor ligands 2-formylpyridine (4-H/4-phenyl)thiosemicarbazone has been studied in the experimental models of MCa mammary carcinoma and TLX5 lymphoma in the CBA mouse. Although all the four tested complexes, bis-[2-formylpyridine(4- phenyl)thiosemicarbazone]ruthenium(II)chloride]Ru(L1)(L1H)Cl, 1], [2-formylpyridine(4-phenyl)thiosemicarbazone]ruthenium(II)-mu- trichloro chloro(imidazole)ruthenium(III)monomethanolate [Ru2(L1)(imz)Cl4.CH3OH, 9]. [2-formylpyridine(4-phenyl)thiosemicarbazone]dichloroimidazoler uthenium(II) [Ru(L1H)(imz)Cl2,10] and bis[2- formylpyridinethiosemicarbazone]ruthenium(II) perchlorate, dihydrate [Ru(L)(LH)ClO4.2H2O, 16], reduced the formation of lung metastases at the same extent only compound 1 caused parallel inhibition of the growth of the primary tumor. The chemical nature of the tested compounds seems to determine the nature of the antitumor effects and the bis-chelates are found to be endowed with greater cytotoxic properties towards primary tumor than the monochelates. This opens up a very interesting point, whether it is the presence of two chelate rings around the Ruthenium(II)/(III) acceptor centre or the increase in the number of the soft (S) donor centers that generates greater cytotoxic properties in the corresponding ruthenium complexes. As far as the reduction of the metastasis formation is concerned, it appears that among the four Ruthenium chelates tested, it is possible to identify structures capable of controlling the spread of tumor to the lungs in the absence of significant cytotoxicity for tumor cells. This finding appears of importance in that it indicates the possibility of a specific mechanism of interaction with cells of the metastatic tumor. In this context it appears necessary to investigate other congeners of this "family" with more sulfur donor sites and particularly those with better water solubility.