Inhibition of angiogenesis by anthracyclines and titanocene dichloride.

The anthracycline antibiotics, daunorubicin, doxorubicin, and epirubicin, which are widely used for treatment of malignancies, have been evaluated for their effect on angiogenesis in relation to the inhibition of collagenase type IV reported previously. In the chick chorioallantoic membrane (CAM) system of angiogenesis, anthracyclines inhibited vascular density at doses of 5-20 micrograms/disc as well as collagenous protein biosynthesis, which is a reliable index of angiogenesis. Similarly, all three anthracyclines inhibited tube formation in the in vitro system of angiogenesis using human umbilical vein endothelial cells (HUVECs) plated on Matrigel. The inhibition was dose-dependent and caused 50% inhibition at concentrations of 2.5-15 micrograms/mL. At concentrations of anthracyclines which prevented tube formation and angiogenesis, there were no cytotoxic effects, as evidenced by methylene blue uptake, and the growth of these endothelial cells was not inhibited. The experimental antitumor agent titanocene dichloride inhibited collagenase type IV from Walker 256 carcinosarcoma with IC50 approximately 0.2 mM. Titanocene also prevented angiogenesis in the CAM and tube formation by HUVECs on Matrigel at concentrations that were without effect on growth or cytotoxicity of endothelial cells or Walker 256 cells in culture. The antiangiogenic effect of the aforementioned antitumor agents at therapeutically attainable concentrations may explain, at least in part, their antitumor properties because angiogenesis is an essential process for tumor growth and metastasis. The antiangiogenic effect is, however, unrelated to metalloproteinase inhibition because higher concentrations are required for that effect than for inhibition of angiogenesis.

Suppression of angiogenesis by the antitumor agent titanocene dichloride.

Titanocene dichloride, which is an active antitumor agent against solid but not blood-borne tumors, suppresses angiogenesis and inhibits biosynthesis of collagenous proteins in the in vivo system of the chorioallantoic membrane of the chick embryo. The agent does not affect total protein biosynthesis in the same system. At non-toxic dose regimens titanocene dichloride retards the growth of Walker 256 carcinosarcoma transplants in rats and reduces the number of seeded implants in the mesenteric bed. At concentrations which suppress angiogenesis and inhibit biosynthesis of collagenous proteins, the agent does not affect the viability of Walker 256 carcinosarcoma cells, or the attachment and proliferation of human A549 lung adenocarcinoma or human umbilical vein endothelial cells in culture. It appears that the antitumor activity of titanocene dichloride may be attributed, at least in part, to its ability to suppress angiogenesis.

Basement membrane biosynthesis as a target for developing inhibitors of angiogenesis with anti-tumor properties.

Basement membrane (BM) exerts profound influence on endothelial cell (EC) behavior. In addition BM is a structural element of blood vessels; in fact at some point of their formation blood vessels are bare EC tubes lined with the BM produced by these EC. We thought, therefore, that a quantitative relationship must exist between the rate of BM synthesis and angiogenesis, and that interfering with BM synthesis must have an effect on angiogenesis. This was found experimentally in the chick chorioallantoic membrane (CAM) system. It was shown that the rate of BM collagen biosynthesis can serve as a biochemical index of angiogenesis and that inhibitors of BM synthesis prevent angiogenesis. GPA 1734 (8,9-dihydroxy-70-methyl-benzo(b)quinolizinium bromide), which inhibits proline and lysine hydroxylations in type IV collagen formation, suppresses angiogenesis in the CAM. Similarly, D609 (tricyclodecan-9-yl-xanthate), which inhibits BM synthesis by an as yet unknown mechanism, also prevents angiogenesis. Structurally related analogs of GPA 1734 and D609 that have no effect on BM biosynthesis are also without effect on angiogenesis. The aforementioned inhibitors of angiogenesis GPA 1734 and D609 have a dose-dependent inhibitory effect on tumor growth in rats bearing Walker 256 carcinosarcoma, without any obvious toxic effects. This effect is probably related to angiosuppression, since structurally related analogs that do not inhibit angiogenesis are without antitumor properties. Also GPA 1734 and D609 have no direct cytotoxic effects on Walker 256 cells in vitro. These results suggest that a search for agents that are specific inhibitors of BM synthesis may provide novel angiosuppressors with potential application in tumor chemotherapy.(ABSTRACT TRUNCATED AT 250 WORDS)

Endothelial injury causes degradation of adjacent basement membranes and promotes their invasion by A549 carcinoma cells.

Experiments in vivo have demonstrated that endothelial cell injury promotes the local arrest of circulating, intravascular cancer cells and the subsequent formation of metastatic tumors. The experiments described here were performed to test the hypothesis that injury of the endothelium also causes damage to the adjacent vascular basement membrane, which in turn facilitates the passage of cancer cells across the vessel wall. Confluent monolayers of bovine pulmonary artery endothelial cells were incubated with 3H-2-deoxyglucose or 3H-proline to label the endothelial cells or the basement membrane, respectively. After adding H2O2 to these cultures, damage of the endothelium and basement membrane was detected by release of the isotopes into the culture medium. The kinetics and magnitude of basement membrane degradation correlated with the damage to the endothelial cells. Evidence for involvement of endothelial proteases in basement membrane injury included identification of a 63-kD gelatinase in the culture medium, inhibition of injury by protease inhibitors and the inability of H2O2 to cause 3H-proline release when applied directly to basement membranes. Scanning electron microscopy demonstrated that a greater number of A549 lung adenocarcinoma cells attached to the basement membrane and endothelium at points of endothelial retraction. However, this was not due to an increase in the adhesive properties of the basement membrane. The media from injured endothelial cultures stimulated the motility of A549 cells in a Boyden chamber assay. Furthermore, in a 24-hour invasion assay, a greater number of A549 cells migrated through injured basement membranes than through control membranes. We conclude that endothelial cell injury can cause enzymatic damage to the underlying basement membrane and postulate that this can facilitate the transvascular passage of cancer cells in vivo.

Effect of divalent metal ions on collagenase from Clostridium histolyticum.

The collagenase from Clostridium histolyticum (EC 3.4.24.3) degrades type IV collagen with Km 32 nM, indicating a high affinity for this substrate. Ferrous and ferric ions can inhibit Clostridium collagenase. Inhibition by Fe++ was of the mixed, non-competitive type, with Ki 90 microM. The inhibitory effect of Fe++ may be due to Zn++ displacement from the intrinsic functional center of this metalloprotease, since in the presence of excess amounts of Zn++ enzyme activity is retained. This inhibitory effect of Fe++ may be common for all types of collagenases, since this ion can also inhibit type IV collagenase purified from Walker 256 carcinoma, with IC50 80 microM. Cu++ can only partially inhibit Clostridium collagenase, while other divalent metal ions such as Cd++, Co++, Hg++, Mg++, Ni++ or Zn++ are devoid of any inhibitory effect on the enzyme.

Basement membrane collagen-degrading activity from a malignant tumor is inhibited by anthracycline antibiotics.

Type IV collagenase activity was previously identified and purified to 7500-fold in homogenates from murine Walker 256 carcinoma, using acetylated [3H]-type IV collagen as a substrate. Anthracycline antibiotics daunorubicin, doxorubicin and epirubicin exhibited a non-competitive, reversible inhibition with Ki 92, 49 and 40 microM, respectively. This inhibitory effect, at therapeutically attainable concentrations of the forementioned antineoplastic drugs, may contribute, at least in part, to their antimetastatic properties. The anthracycline derivatives: 4-demethoxydaunorubicin, 4'-iododoxorubicin and 4-demethoxy-3'-deamino-3'-hydroxyepirubicin were without inhibitory effects at comparable concentrations. Other antineoplastic agents, such as belomycin, carmustine, cisplatine, etoposide, methotrexate, mitotane and teniposide did not exhibit any inhibitory effect at concentrations up to 1.0 mM.

Antitumor effect of GPA1734 in rat Walker 256 carcinoma.

Inhibition of angiogenesis offers an alternative approach to cancer chemotherapy, since solid tumor growth has an absolute dependency on angiogenesis. We have previously shown that 8,9-dihydroxy-7-methyl-benzo [b]quinolizinium bromide (GPA1734) is a basement membrane synthesis inhibitor, and that this compound acts as an antiangiogenic agent in the chick chorioallantoic membrane. When a piece of 10 mg from a Walker 256 carcinoma was implanted into the peritoneal cavity of rats, tumor grew to about 15 g within nine days after transplant. Daily treatment of Walker 256 carcinoma bearing animals with GPA1734, at doses 10-100 mg/kg intraperitoneally, restrained tumor growth in a dose dependent manner. Macroscopic examination showed tumor cells growing in spherical masses 5-8 mm in diameter, indicative of absence of neovascularization. GPA1734 at 300 microM had no direct effect on Walker 256 carcinoma cell culture growth. The antitumor effect of this agent on Walker 256 carcinoma may be related to its antiangiogenic properties.

Basement membrane biosynthesis as a target to tumor therapy.

Tricyclodecan-9-yl-xanthate (D609) was identified as an agent that caused selective killing of tumor cells by an unknown mechanism of action. We report an inhibition by D609 of basement membrane collagen biosynthesis in the chick chorioallantoic membrane system in vitro. In the same system in vivo D609 inhibits angiogenesis. Also treatment of rats bearing Walker 256 carcinoma with D609 results in a dose-dependent antitumor effect. These results indicate that basement membrane synthesis may be a target for developing anti-angiogenic compounds with antitumor properties.

Angiogenesis is associated with collagenous protein synthesis and degradation in the chick chorioallantoic membrane.

Extracts of the chick embryo chorioallantoic membrane (CAM) obtained from 7-20 day old embryos, contained enzyme activity that could degrade type IV collagen. Peak enzyme activity was observed on days 8-10 of embryogenesis, which coincides with the stage of maximum angiogenesis. This activity decreased to lowest values at days 13-15 and increased thereafter up to day 20. Maximum rate of collagen biosynthesis in CAM was observed between days 7 and 10, with a drastic decrease at day 12, when vascular density has reached a plateau. The type IV collagen-degrading activity of CAM was of the metalloprotease type, since it was inhibited by 1,10-phenanthroline and EDTA but was also partially inhibited by serine and thiol protease inhibitors.

Mode of action of razoxane: inhibition of basement membrane collagen-degradation by a malignant tumor enzyme.

Razoxane is an antitumor agent structurally related to EDTA. Its cytotoxic mechanism of action has been shown to involve interference with cell division and reduction of the gross rate of DNA synthesis. In this study we present evidence that razoxane, at therapeutically attainable concentrations, inhibits type IV collagen and basement membrane degradation by an enzyme isolated from malignant tumors. This effect is attributed to the chelating properties of razoxane and may explain the antimetastatic properties, by means of stabilization of tumor blood vessels, which have been associated with the action of the antitumor drug.

Comparative evaluation of mitogenicity and basement-membrane-degrading activity of Pseudomonas aeruginosa slime glycolipoprotein and alginate.

Alginate from a heavily mucoid Pseudomonas aeruginosa strain and slime glycolipoprotein obtained from the revertant nonmucoid variant of the mucoid strain were tested for mitogenic activity on human peripheral lymphocytes and for degradation of 3H-labeled basement membranes of the anterior lens capsule of bovine eyes. Slime glycolipoprotein exerted mitogenic activity in concentrations from 50 to 200 micrograms/ml, whereas alginate was not mitogenic as shown by [3H]thymidine uptake. Alginate did not show any basement membrane degradation, whereas slime glycolipoprotein exhibited basement-membrane-degrading activity from 35 to 450 micrograms/ml in a dose-related manner. This activity was inhibited by metal chelators but not thiol protease inhibitors. The results suggest that alginate lacks the mitogenic and biodegrading activities of slime glycolipoprotein; these activities nevertheless need further investigation.

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.

Usefulness of serial determinations of myoglobin and creatine kinase in serum compared for assessment of acute myocardial infarction.

Twenty-one patients with their first myocardial infarction underwent serial blood sampling every 2 h for determination of serum creatine kinase (CK) and myoglobin during the first 48-72 h after onset of pain. The first blood sample, obtained at a mean time of 4.4 h after infarct onset, invariably showed increased myoglobin (mean, 8.3-fold normal), whereas CK was often normal (mean, 1.6-fold normal). Peak myoglobin values occurred earlier than peak CK values (9.9 h vs 21.6 h, p less than 0.0005), but there was a significant correlation of peak values (myoglobin = 0.384CK - 0.264, r = 0.794, p less than 0.0005). The mean exponential disappearance rate (Kd) of CK was 0.00106 min-1 and of myoglobin was 0.00265 min-1 (p less than 0.0005). The disappearance of myoglobin was well described by a mono-exponential expression except in two patients. The total duration of the increase in myoglobin was significantly less than that of CK (34.7 h vs 74.4 h, p less than 0.0005).

Intravenous hyaluronidase therapy for myocardial infarction in man: double-blind trial to assess infarct size limitation.

Patients with their first myocardial infarction not initially complicated by severe atrioventricular block or power failure were given a skin test and then randomized to receive either hyaluronidase or placebo in double-blind fashion. Hyaluronidase, 500 IU/kg i.v., was given every 6 hours for 42 hours. Of the 48 eligible patients, 26 received hyaluronidase and 22 received placebo. The mean CK serum entry was 3140 +/- 2111 mIU/ml (mean +/- SD) in hyaluronidase patients and 3574 +/- 1476 mIU/ml in placebo patients (p less than 0.21). The mean infarct size was 54.6 +/- 35.8 CK gram-equivalents in the hyaluronidase patients and 64.0 +/- 31.1 CK gram-equivalents in the placebo patients (p less than 0.20). Among the 21 patients treated within 6 hours of the onset of infarction, the difference in infarct size was greater (p less than 0.15). There was no significant difference in the incidence of power failure, ventricular arrhythmias, recurrence of ischemic pain, infarct extension or mortality. No benefit of hyaluronidase was demonstrated in this study, which was designed to detect a 50% reduction of infarct size. However, to detect a 20% reduction in infarct size would require a much larger study population.

Radioimmunoassay for dog myoglobin.

A radioimmunoassay specific for dog myoglobin (MGB) has been developed. Antibody (Ab) to purified dog heart MGB was prepared in rabbits and the Ab was labelled with 125I using the chloramine-T procedure. The assay is conducted at room temperature with addition of second Ab at 24 hr, the forward reaction being 95% complete at this point and irreversible. The assay is free of matrix affects. The working range is 20 to 360 ng/ml. Coefficients of variation for within run replicates are 10.5% (low) and 4.4% (high), and for between run replicates are 13.8% (low) and 7.6% (high). Serial measurement of serum MGB in dogs undergoing experimental myocardial infarction indicates that appearance time, peak time, and disappearance rate are respectively, 1.1 hr, 7.7 hr and 0.0025 min-1 for MGB and 2.6 hr, 13.35 hr, and 0.0018 min-1 for CK.

Myocardial infarction size from serial CPK: variability of CPK serum entry ratio with size and model of infarction.

To study the variability of the fraction of CPK released from the infarcted heart which enters the serum (serum entry ratio, or SER) with size and model of infarction, nine dogs underwent homogeneous infarctions (LAD ligation) of varying sizes, and 10 dogs underwent scattered infarctions (left coronary embolization). In homogeneous infarcts there was an inverse linear relationship of SER to infarct size (IS) (SER = -0.8514% LV + 0.345, r = 0.98). No such relationship was found for scattered infarcts. CPK Kd (exponential disappearance constant for CPK) was not significantly different in homogeneous (-0.00178 min-1) vs scattered infarcts (-0.00195 min-1). Although similar IS was produced in each (homogeneous 19.9% LV, scattered 18.4% LV) cumulative CPK serum entry (CPKr) was much lower in homogeneous (4175 mlU/ml) vs scattered infarcts (7,296 mlU/ml). SER was also much lower in homogeneous (17.7%) vs scattered infarcts (29.0%) (P less than 0.025). Cumulative CPK plateau occurred significantly later in homogeneous (15.8 hours) vs scattered infarcts (11.7 hours) (P less than 0.01). Further corrections to the serial CPK equations for IS determination are indicated. The method may not be applicable in some infarct situations, e.g., scattered infarction.