Biomolecular study and conjugation of two para-aminobenzoic acid derivatives with serum proteins: drug binding efficacy and protein structural analysis.

Two aminobenzoic acid derivatives DAB-0 and DAB-1 showed distinct biological properties on murine bladder cancer (BCa) cell line MB49-I. In contrast to DAB-1, DAB-0 does not possess any anti-inflammatory activity and is less toxic. Furthermore, DAB-0 does not interfere with INFγ-induced STAT1 activation and TNFα-induced IκB phosphorylation, while DAB-1 does. In order to rationalize these results, the binding efficacy of DAB-0 and DAB-1 with serum proteins such a human serum albumin (HSA), bovine serum albumin (BSA) and beta-lactoglobulin (ß-LG) was investigated in aqueous solution at physiological pH. Multiple spectroscopic methods and thermodynamic analysis were used to determine the binding efficacy of DAB-0 and DAB-1 with serum proteins. Drug-protein conjugation was observed via through ionic contacts. DAB-1 forms stronger adducts than DAB-0, while ß-LG shows more affinity with the order of stability ß-LG > BSA > HSA. The stronger complexation of DAB-1 with serum proteins might account for its biological potential and transport in the blood. The binding efficacy ranged from 40 to 60%. Major alterations of protein secondary structures were detected upon drug complexation. Serum proteins are capable of delivering DAB-1 in vitro.Communicated by Ramaswamy H. Sarma.

The natural flavonoid silybin improves the response to Photodynamic Therapy of bladder cancer cells.

Photodynamic Therapy (PDT) is an anticancer treatment based on photosensitisation of malignant cells. The precursor of the photosensitiser Protoporphyrin IX, 5-aminolevulinic acid (ALA), has been used for PDT of bladder cancer. Silybin is a flavonoid extracted from Silybum marianum, and it has been reported to increase the efficacy of several anticancer treatments. In the present work, we evaluated the cytotoxicity of the combination of ALA-PDT and silybin in the T24 and MB49 bladder cancer cell lines. MB49 cells were more sensitive to PDT damage, which was correlated with a higher Protoporphyrin IX production from ALA. Employing lethal light doses 50% (LD50) and 75% (LD75) and additional silybin treatment, there was a further increase of toxicity driven by PDT in both cell lines. Using the Chou-Talalay model for drug combination derived from the mass-action law principle, it was possible to identify the effect of the combination as synergic when using LD75, whilst the use of LD50 led to an additive effect on MB49 cells. On the other hand, the drug combination turned out to be nearly additive on T24 cells. Apoptotic cell death is involved both in silybin and PDT cytotoxicity in the MB49 line but there is no apparent correlation with the additive or synergic effect observed on cell viability. On the other hand, we found an enhancement of the PDT-driven impairment of cell migration on both cell lines as a consequence of silybin treatment. Overall, our results suggest that the combination of silybin and ALA-PDT would increase PDT outcome, leading to additive or synergistic effects and possibly impairing the occurrence of metastases.

Heparin increases the adhesion of murine mammary adenocarcinoma cells (LM3). Correlation with the presence of heparin receptors on cell surface.

Mastocytosis is a common feature around solid tumors. Due to mast cell (MC) degranulation, heparin and other chemical mediators are released to surrounding tissues. The aim of this paper is to investigate the role of heparin and chemically modified heparins, on a murine mammary adenocarcinoma cell line adhesion properties, and the relationship with the presence of heparin binding sites in tumor cells. We show that heparin increases tumor cell adhesion in a dose-dependent manner. When the number of heparin binding sites was regulated, by culturing the cells with different FCS concentration for 24 hours, a correlation between binding capacity and heparin effect on cell adhesion was observed. The increment on cell adhesion by heparin was lower on cells with less heparin binding sites. Moreover, only heparin and a chemically modified heparin (partially N-desulfated N-acetylated), which bound to heparin-receptor, retained the ability to stimulate cell adhesion, while other modified heparins lost both effects. The increase in cell adhesion was observed on plastic dishes, albumin, as well as on fibronectin pre-coated ones suggesting that heparin effect is substratum independent. Our results show a direct relation between heparin binding to specific cell receptors and increase in cell attachment.

Heparan sulfate, heparin, and heparinase activity detection on polyacrylamide gel electrophoresis using the fluorochrome tris(2,2'-bipyridine) ruthenium (II).

The paper shows the ability of the fluorochrome tris(2,2'-bipyridine) ruthenium (II) (Rubipy) to detect heparan sulfate, heparin, and heparinase activity of M3 murine mammary adenocarcinoma cells as well as bacterial heparinases I, II, and III in native polyacrylamide gel electrophoresis (PAGE). The technique is based on the electrophoretic mobility of high molecular weight heparins and subsequent staining with Rubipy (50 micrograms/mL). The minimum content of heparin detected by fluorescence in a UV transilluminator was 25-50 ng. The number of Rubipy molecules bound to heparin, determined in relationship to the number of disaccharide units (DU), showed that two to six heparin disaccharide units are bound by each fluorochrome molecule. Scatchard plot analysis showed one Rubipy-binding site (Kd = (8.56 +/- 2.97) x 10(-5) M). Heparinase activity was determined by densitometric analysis of the fluorescence intensity of the heparin-containing band of the gel. While heparinase I (EC 4.2.2.7.) degraded heparin and, to a lower degree, partially N-desulfated N-acetylated heparin (N-des N-Ac), heparinase II (no EC number) could efficiently degrade heparan sulfate (HS) and partially N-des N-Ac heparin. Finally, heparinase III (EC 4.2.2.8.) degraded HS almost exclusively. Only heparin and N-des N-Ac heparin were substrates for M3 tumor cell heparinases. We describe a qualitative, sensitive and simple method to detect heparinase activity and determine its substrate specificity using Rubipy fluorescence with heparin and heparan sulfate in multiple biological samples tested in parallel.

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.

Cathepsin B levels in urine from bladder cancer patients.

There is accumulating evidence that cysteine proteinase activity plays an important role in cancer cell invasion and metastasis. Previously we demonstrated that cathepsin B (CB) plasma activity is increased in patients with transitional bladder cancer (TCC). In this work we have attempted to determine whether urine CB protein levels could be used as tumor marker in bladder cancer patients. Urine CB levels were evaluated employing a dot blot method, in 30 patients with TCC, 21 patients successfully treated from TCC without evidence of disease at the moment of urine collection (NED) and in 30 healthy volunteers. The median value (Md) of the control group was 3.8 microg CB/ml. Significantly higher urine CB values (Md: 5.9 microg/ml) were found in the TCC group. A high CB value was also found in the NED group (5.0 microg/ml). Urine CB values over the 5.2 microg/ml (cut-off point) were observed in 63% of TCC patients, 48% of NED and 8% of the control group. Only 4% NED patients had CB values over 13.0 microg/ml while 33% of TCC patients surpassed this value. Thus, urine CB might be a potential marker for transitional bladder cancer diagnosis.

Human papillomavirus (HPV) DNA in penile carcinomas in Argentina: analysis of primary tumors and lymph nodes.

Among sexually transmitted diseases, infection by human papillomavirus (HPV) has become one of the most important. On the other hand, though epidemiological data show that some HPV types are closely associated with cervical cancer, few reports have been found with reference to penile carcinoma because of its rare occurrence. The aim of this study was to investigate the relationship between HPV infection and penile cancer in Argentina. A retrospective study was carried out on 38 white men with penile squamous-cell carcinoma. Sixty-five archival fixed biopsies taken from 34 primary penile tumors, 25 nodal metastases, 1 skin "satellite" metastasis and 5 histologically normal lymph nodes were used as specimens. HPV detection and typing were carried out by the polymerase chain reaction (PCR) using generic primers, combined with single-stranded conformational polymorphism (SSCP) analysis. HPV DNA was found in 71% patients, corresponding 81% of them to "high risk" types, with predominance of HPV 18. Both primary tumors and metastases showed concordance of HPV occurrence and type in both lesions. In 3 patients, HPV 16 was detected not only in primary tumors and metastases, but also in histologically normal lymph nodes. Our data indicate that most penile carcinomas in Argentine patients are etiologically related to HPV, especially to "high risk" genital types. The agreement in HPV detection between primary tumors and metastases suggests a potential viral role in tumor progression. HPV detection in otherwise histologically normal lymph nodes might be useful as early marker of a metastatic process.

A synthetic, nitrogenated antimetastatic and anti-angiogenic compound with low toxicity in vivo.

The design of more effective therapies for metastatic disease involves development of new compounds able to specifically block the malignant process. We demonstrated previously that a new synthetic nitrogenated compound 3'-1-chloroethyl-2,3-dihydro-1H-imidazo-(2, 1-i)-purine-4-ium-7-yl-3'-deoxy-1',5', 6'-tri-O-(methylsulfonyl)-muco-inositol chloride (DIC) had an anti-proliferative activity on tumor cells in vitro. In the present work we demonstrate that DIC induces apoptosis on the LM3 murine mammary adenocarcinoma cell line in vitro and has anti-angiogenic activity in vivo. We also evaluated toxicity, biodistribution and anti-neoplastic properties of DIC in vivo. Toxicity studies allowed us to establish the LD50 (750 mg/kg body weight). Administration of 250 mg/kg/day (LD10) for 6 days did not cause overt toxic effects. Biodistribution assays revealed that DIC was rapidly eliminated (60% at t=10 min), although it accumulated in tumor tissue at higher concentrations than in other tissues. Daily s.c. treatment with DIC (LD10) for 24 days significantly reduced the number of spontaneous lung metastases. These results suggest that DIC has the ability of impairing the metastatic development by inhibiting angiogenesis and inducing apoptosis on tumor cells.

Differential nitric oxide release and sensitivity to injury in different murine mammary tumor cell lines.

The purpose of this study was to determine whether nitric oxide (NO) production by different mammary tumor cell lines correlated with their sensitivity to NO mediated injury. Three mammary tumor cell lines LM2, LM3 and LMM3 syngeneic to BALB/c mice were cultured in vitro with IFNgamma + LPS. Different levels of NO production among the three lines were detected in culture supernatants. The only tumor cell line which did not produce NO (LM2) showed the highest sensitivity to SNP-derived NO cytotoxicity (87%), while LM3 and LMM3 which both produced higher levels of NO than LM2, showed lower cytotoxicity by SNP (39% and 22% respectively). Spleen cells (SC) from M2 tumor bearing mice (TBM) were able to lyse LM2 cells by NO-dependent mechanisms. SC from M3-TBM exerted cytotoxicity against LM3 cells mainly by NO-independent mechanisms. Thus, we postulate an inverse correlation between NO production and NO mediated cytotoxicity in the three mammary tumor cell lines. It is possible that tumor cells producing NO develop mechanisms to resist NO injury.

Insight into the profibrinolytic activity of heparin: effects on the activation of plasminogen mediated by urokinase.

The aim of this work was to clarify the role of urokinase-type plasminogen activator (uPA) on the profibrinolytic activity of heparin, chemically modified heparins [partially: N-desulfated (N-des), N-desulfated N-acetylated (N-des N-ac), O-desulfated (O-des), O/N-desulfated N-acetylated (O/N-des N-ac)] and heparan sulfate. Binding competition assays of plasminogen and uPA to heparin-sepharose demonstrated that heparin bound to both enzymes. Moreover, in the presence of increasing amounts of heparin, plasminogen activation mediated by uPA occurred as a bell-shaped curve, suggesting the formation of a ternary complex. In contrast, all chemically-modified heparins lacked this cofactor activity, although N-des and heparan sulfate partially retained the uPA binding capacity, and O-des partially bound to both plasminogen and uPA. Plasmatic euglobulins from mice treated with heparin, as well as with modified heparins with uPA binding capacity, presented a 2-fold enhancement of 47 kDa lytic band, as assessed by zymographic analysis. Western blotting analysis anti-uPA (47 kDa) showed that the enhanced uPA activity correlated with a true increase in uPA protein levels. These results suggest that the profibrinolytic activity of heparin mediated by uPA could be caused by an increase in uPA protein levels rather than by a cofactor activity mediated by a formation of ternary complexes.

Varying patterns of expression of insulin-like growth factors I and II and their receptors in murine mammary adenocarcinomas of different metastasizing ability.

We studied the expression of insulin-like growth factors I (IGF-I) and II (IGF-II) and their receptors (IGF-R) in 2 related murine mammary adenocarcinoma in vivo lines, M3 and MM3, with different metastasizing ability. We further investigated the effects of IGFs on the secretion of a key enzyme in the metastatic cascade, the urokinase-type plasminogen activator (uPA) in M3 and MM3 cells. M3 is a spontaneous mammary tumor originated in BALB/c mice, with a 40% incidence of lung metastases. MM3 variant, obtained by successive s.c. implants of M3 lung metastases into syngeneic mice, shows a 95% incidence of lung metastases. Similar levels of expression of IGF-I protein were found in M3 and MM3 tumors, whereas IGF-II expression was 4-fold higher im MM3. RNAse protection assays showed similar levels of IGF-I mRNA in M3 and MM3 tumors and revealed a 4-fold increase in IGF-II transcripts in MM3 tumors compared with M3. Authentic IGF-I and II messages were also found in primary cultures of M3 and MM3 cells. IGF-I mRNA levels were similar in both cultures and, as described for solid tumors a 5-fold increase in IGF-II message was detected in MM3 cells. The presence of type I and mannose-6-phosphate (Man-6P)/type II IGF-R was demonstrated in both M3 and MM3 tumors. A 2-fold increase of type I IGF-R was detected in MM3 tumors compared with M3. Man-6P/type II IGF-R levels were 2-fold lower in MM3 tumors than in M3. As observed in tumor membranes, type I IGF-R concentrations were higher and Man-6P/type II IGF-R lower in cultures of MM3 epithelial cells compared with MM3 cells. In addition, we found that IGF-I enhanced secreted uPA activity in both M3 and MM3 cells while IGF-II only stimulated uPA secretion in MM3 cells.

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.

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.

Growth inhibition in vitro of murine mammary adenocarcinoma cells by heparin and chemically modified heparins.

Heparin, a highly sulfated polysaccharide used as an antithrombotic and anticoagulant, inhibits proliferation of several cell types. We have investigated the effect of heparin and chemically modified heparins on the growth of a cell culture of a murine mammary adenocarcinoma (M3). We found that heparin inhibited the proliferation of M3 cells growing either with or without 2% fetal calf serum (FCS) in a dose-dependent and reversible fashion. Several heparins with different anticoagulant properties showed a similar antiproliferative effect. Histological assays showed that heparin was internalized and appeared in cytoplasmic vesicules. O-desulfated, O/N-desulfated N-acetylated and N-desulfated heparins lost their antiproliferative activity, while N-desulfated N-acetylated heparin significantly inhibited cell proliferation with or without FCS. The finding of an antiproliferative action of N-desulfated N-acetylated heparin which does not show anticoagulant activity suggests a possible therapeutic role for this compound as an antineoplastic drug.

Effect of host-organ environment on the in vivo and in vitro behavior of a murine mammary adenocarcinoma.

We investigated the role that organ environment may play in determining the homing of disseminated cells from a murine mammary adenocarcinoma moderately metastatic to lung (M3). Conditioned medium (CM) from normal lung was able to enhance both local and metastatic growth. It increased the number of lung colonies when inoculated together with tumor cells via intravenous or separately via intraperitoneal route. Several in vitro studies were performed in order to elucidate possible mechanisms. It was shown that lung CM stimulated the in vitro growth and the migration of M3 cells. Normal kidney and liver CM lacked all these capacities.

Action of nitrogenated and sulfonylated inositol derivatives upon the proliferation in vitro of normal mouse cells and tumor mouse cells.

Despite the major advances of cancer chemotherapy during the past 40 years, host toxicities and drug resistance justify the need to continue the search for new antineoplastic agents. In the present work, we have studied the effect of six synthetic drugs on the in vitro growth of two murine mammary adenocarcinomas (M3 and MM3), as well as on normal embryonic cells. AI, MIC and MPI are purines coupled to a sulfonylated inositol, while DIC and DEI have nitrogen mustard as substituent. Methylsulfonylmucoinositol was the common substituent. Our results indicated that only drugs substituted with nitrogen mustards had an antiproliferative effect. DEI was more effective on tumor cells than on normal cells.

[Modulation of angiogenesis induced by lymphocytes by extracellular matrix proteins]. / Modulación de la angiogénesis inducida por linfocitos por proteínas de la matriz extracelular.

The neovascularization is a known event in the de development of tumors. The progressive growth of solid tumors is strictly dependent on angiogenesis. Furthermore, shedding of tumor cells into the circulation is not observed in a prevascular phase of tumors. Therefore, the inhibition of angiogenesis could be a good target for cancer control. Lymphocytes from, tumor bearing-mice were capable of inducing neovascular response in the skin of syngeneic mice. This response was named syngeneic lymphocyte-induced angiogenesis (SLIA). This work was an attempt to study if two proteins present in extracellular matrix, collagen and fibronectin (FN), could modulate lymphocyte-induced angiogenesis. The angiogenic response induced by lymphocytes from S13 tumor bearing-nice in the skin of BAL/c mice was blocked by treatment with FN and Gly. Arg. Gly. Asp. peptide. On the contrary, collagen and Gly. Arg. Gly. Asp. Ser did not modify SLIA response.

Modulación de la angiogenesis inducida por linfocitos por proteinas de la matriz extracelular / Modulation of angiogenesis induced by lymphocytes by extracellular matrix proteins

La neovascularización es uno evento importante en el desarrollo y crecimiento tumoral. La liberación de células tumorales en la circulación no se observa en la fase avascular del crecimiento tumroal. Los linfocitos de ratones portadores de tumor son capaces de inducir una respuesta angiogénica cuando se inoculan intradérmicamente en la piel de animales singenéicos. Esta respuesta recibe el nombre de SLIA. En este trabajo se estudia proteínas presentes en la matriz extracelular, colágeno y fibronectina (FN) pueden modificar la respuesta antiogênica inducida por linfocitos de ratones portadores de tumor S13. El tratamiento de los linfocitos con FN o con el péptido Gly. Arg. Glyp. Asp. inhibió la angiogénesis. Por el contrario el colágeno y el péptido Gly. Arg. Gly. Asp. Ser no modificaron la respuesta neovascular inducida por los linfocitos de portadores de tumor