Experimental Tumors In Mice Research Articles

O-047 - Effects of Japanese Kampo medicine on experimental tumors In mice and its antitumor mechanism.

O-047 - Effects of Japanese Kampo medicine on experimental tumors In mice and its antitumor mechanism.

Computer classification of experimental brain tumors in mice

The purpose of this study was to develop a mathematical model which would be easy to use and which could provide an objective classification of experimental brain tumors. 250 brain tumors (glioblastomas, astrocytomas, astroblastomas, oligodendrogliomas, ependymomas, fibrosarcomas and giant cell sarcomas), induced in mice, were studied. In every case the same 50 histological characteristics were analyzed. For astroblastomas, oligodendrogliomas and ependymomas the diagnosis given by the neuropathologist and that given by the computer corresponded in 100% of the cases. However, some fibrosarcomas and giant cell sarcomas were not grouped in the same diagnostic category by the computer as that assigned by the neuropathologist. Thus an overall efficiency of 94.35% was obtained. This simple and efficient system of classification allows for further statistical analyses and makes it possible to correlate the results presented by different authors, thus providing for unity in all those works concerned with experimental neurooncology.

Depletion of tumour versus normal tissue glutathione by buthionine sulfoximine.

We have investigated in detail the effects of buthionine sulfoximine (BSO), a selective glutathione (GSH) depleting agent, on the GSH contents of a number of normal tissues and three experimental tumours in mice. Significant variations in the rate and degree of GSH depletion and recovery were observed among the normal tissues. Following a dose of 2.5 mmol kg-1 BSO, GSH nadirs were reached by approximately 5 h for the liver and kidney, 8 h for the lung and bone marrow, 12 h for red blood cells (RBCs) and by 24 h for the heart. The degree of depletion was greatest for the kidney (80%), liver (74%) and bone marrow (83%), intermediate for the heart (54%) and lung (40%), and least for RBCs (13%). Recovery of GSH content was fastest for the liver followed in descending order by the kidney, the lung, the bone marrow, RBCs and the heart. In contrast, the rate and extent of GSH depletion and recovery showed considerably less variation among the 3 murine tumours. In the tumours GSH nadirs were reached by 10-12 h. The extent of depletion was about 55-65%. Recovery of GSH levels in the tumours required 48 h or more, a longer period than required by the liver, kidney and lung but shorter than that needed for the bone marrow, heart and RBCs. Attempts to preferentially deplete tumour GSH by exploiting the differences in recovery rates between normal tissues and tumours were only partially successful. Multiple BSO dosing at 16 h intervals allowed the liver to recover between doses, but the recovery in the kidney, lung and bone marrow was only partial and no recovery was seen in the heart. Finally, dose-depletion relationship investigations showed that, with the exception of the lungs, GSH depletion could be achieved in tumours with doses of BSO lower than those required for normal tissues.

The theory of photodynamic therapy dosimetry: consequences of photo-destruction of sensitizer.

Photodynamic dose is defined as the area under the curve of sensitizer level plotted as a function of light dose. This is a photochemical definition of dose. We will show that this definition is useful in predicting photobiological response. The photodestruction of sensitizer during photodynamic therapy is shown to result in an upper limit on the photodynamic dose which can be delivered by an unlimited light dose. This limit results in the opportunity to make total photodynamic dose uniform to considerable depths (one to two centimeters). The existence of thresholds for permanent tissue damage allows protection of normal tissue from the large light doses required to achieve this limiting dose deep in the tissue. Higher sensitizer levels in the tumor permit tumor destruction while the normal tissues are protected. A clinical trial to determine the proper level of injected dose necessary for these results is required. This theory of photodynamic therapy (PDT) dosimetry is tested in the DBA-SMT experimental mouse tumor system. Combinations of drug and light which are not reciprocal but are nearly equal by this theory are shown to give equivalent tumor control at seven days post treatment. Reciprocal combinations of drug and light fail to give equivalent results when they ae selected using the theory to choose a combination where reciprocity should fail.

Protease Inhibitors in Processed Plant Foods

Plants contain a wide variety of protein protease inhibitors. However, most is known about the serine protease (trypsin and chymotrypsin) inhibitors found in legumes, particularly soybeans. These inhibitors in unheated legume protein (a) impair the protein's nutritional quality, (b) induce pancreatic hyper-trophy in some but not all experimental animals, (c) enhance the action of chemical pancreatic carcinogens in Wistar rats but not hamsters or mice, (d) are reported to be carcinogenic to the pancreas of Wistar rats and (e) inhibit certain experimental tumors in rats, mice and hamsters. The physiological significance of the low residual protease inhibitor levels in commercially processed plant proteins and human foods prepared from such proteins remains to be resolved. Plant proteins prepared for human consumption, however, contain low levels of pro-tease inhibitor activity which are of no nutritional concern in animals or humans.

Role of metabolism in effects of diflubenzuron on growth of B16 melanomas in mice.

The insect growth regulator diflubenzuron (DFB), which also inhibits growth of experimental tumors in mice, was studied to determine the influence of in vivo microsomal metabolism on its antitumor activity. DFB inhibits chitin synthesis and growth of imaginal epidermis in insects and suppresses melanogenesis and uptake of nucleosides in mouse melanoma cells, but the means of cell growth regulation and the role of metabolism of DFB in such regulation have not been established. Five daily injections of DFB (total of 4000 mg/kg) into C57BL/6 mice with B16 melanomas induced an acute 11-20% decrease in tumor volume and a 2-3 day increase in the initial tumor volume doubling time (Td), but at mid-treatment tumors regained maximum (control-like) rate of volume increase. Tumors in mice conditioned with a mixed function oxidase inhibitor (CoCl2) and treated with DFB did not decrease in mean volume, but their rate of volume increase was reduced by about 75% and the Td was increased by 4.2 days. In contrast, induction of mixed function oxidase with 3-methylcholanthrene (3-MC) or beta-napthaflavone (B-NF) enhanced the effects of DFB by a factor of 1.5 to 2.0. Therefore, aromatic hydroxylation of DFB may be required for tumor growth regulation. Three metabolites of DFB--two hydroxylated forms and a scission product, 4-chlorophenylurea (CPU), were also tested for tumor growth regulation. CPU was ineffective; a form oxidized at the 3 carbon of the phenyl ring (3-OH-DFB) was only marginally effective; but the 2-carbon form (2-OH-DFB) induced a 24% decrease in mean tumor volume and a 2.4 day increase in Td. Pretreatment with 3-MC and treatment with 2-OH-DFB also resulted in a 24% decrease in tumor volume and a 2.2 day increase in Td, but also reduced tumor volume increase to 20% between the 5th and 10th days after the initial 2-OH-DFB injection, compared to a 125% increase without 3-MC. Further, 3-MC pretreatment caused the otherwise marginally effective 3-OH-DFB to become almost as effective as 2-OH-DFB. These data support our previous report that DFB alters tumor growth and show that mixed function oxidase enhances effects of DFB, 2-OH-DFB and 3-OH-DFB.

Development and some characteristics of a P388 leukemia strain resistant to 1, 2 : 5, 6-dianhydrogalactitol

Repeated intraperitoneal treatment of standard P388 mouse leukemia with dianhydrogalactitol (DAG) resulted in the development of a P388/DAG experimental mouse tumor which was resistant to the drug. Resistance was stable without DAG treatment throughout 80 passages. P388/DAG shows cross-resistance to alkylating agents such as nitrogen-mustard, cyclophosphamide and diacetyl-DAG but not to selected antimetabolites and tubulin binders and exhibits reduced sensitivity to nitrosoureas. Resistance to DAG could not be overcome by the administration of maximally tolerated dose of DAG to tumor bearing mice. The resistant tumor is one chromosome short and shows a 13-fold increase of cells possessing a submetacentric marker chromosome.

Porphyrin photosensitization and phototherapy.

Porphyrin photosensitization and phototherapy.

Activity of safracins A and B, heterocyclic quinone antibiotics, on experimental tumors in mice.

Safracins A and B, new antibiotics produced by Pseudomonas fluorescens A2-2, were tested for antitumor activity against mouse tumors. Structurally, these antibiotics belong to the saframycin family of antibiotics, and safracin B is 21-hydroxysafracin A. They showed antitumor activity against L1210 and P388 leukemias and B16 melanoma. The toxic and effective doses of safracin B were much lower than those of safracin A. Safracin B also prolonged the life span of tumor-bearing mice to a greater extent than safracin A. These results indicate that the alpha-carbinolamine structure plays an important role in the antitumor action of this type of antibiotic. Both safracins were, however, ineffective when their administration route differed from that used for inoculating tumor cells.

Recovery from potentially lethal damage after X-irradiation in three experimental tumors in mice.

Potentially lethal damage repair or recovery (PLDR) after X-irradiation was examined in three experimental murine tumors, EMT6 sarcoma, SCCVII carcinoma and RIF1 sarcoma, by an in vivo-in vitro assay. All tumors were transplanted subcutaneously (SC) and, in the case of EMT6, also intradermally (id), in the thighs of syngeneic mice. Apparent PLDR was observed at high dose levels in the id and sc EMT6 sarcomas and in the sc SCCVII carcinoma, but not in the sc RIF1 sarcoma. In both id EMT6 and SCCVII tumors, PLDR appeared to be complete within 9 hr after X-irradiation. Dose-modifying factors due to PLDR evaluated at the surviving fraction of 0.01 were 1.34, 1.15, 1.24 and 0.97 for id EMT6, sc EMT6, SCCVII and RIF1 tumors, respectively. The amount of PLDR correlated inversely with the velocity of tumor growth in vivo, suggesting that slowly growing tumors might be proficient in PLDR. Although PLDR in id EMT6 and SCCVII tumors was evident in the dose range above 15 Gy, the capacity to recovery from PLD became smaller at lower doses; in SCCVII tumors, this phenomenon was negligible below 7.5 Gy. PLDR did not seem to be a major factor influencing the radiocurability of these murine tumors, especially at low dose levels.

Depletion of glutathione in vivo as a method of improving the therapeutic ratio of misonidazole and SR 2508

Depletion of intracellular glutathione (GSH) can enhance misonidazole (MISO) radiosensitizing efficacy both in vivo and in vitro. However, such treatments may also enhance the systemic toxicity in animals. The purpose of the present study was to test various ways of depleting GSH levels in a variety of experimental mouse tumors, to measure the improvement in the efficacy of MISO and its less toxic analog SR 2508 by this depletion, and to determine the effect of daily GSH depletion on the toxicity of MISO and SR 2508. GSH levels were measured daily for 5 days in tumors, livers and brains of mice injected daily with buthionine sulfoximine (BSO), with or without diethylmaleate (DEM). To investigate tumor variability we studied 5 different tumors: EMT-6, RIF-1, KHT, SCC VII, and B16 melanoma. The efficacy of MISO and SR 2508 was evaluated using the KHT and SCC VII tumors either by the regrowth delay assay or by the in vivo/in vitro clonogenic assay. The drug toxicity was evaluated by weight loss and by death. Daily doses of 3 mmole/kg BSO depleted tumor levels of GSH to 20 to 40% of controls by 6 hr after each injection. Injection of DEM (300 mg/kg) 6 hr after BSO further enhanced the depletion. Administration of MISO or SR 2508 at the time of maximum GSH depletion enhanced the MISO efficacy by factors of 2.5 to 8 for depletion to 8% of controls by BSO + DEM, but no enhancement of SR 2508 was seen with tumors at 20% GSH levels achieved with BSO alone in the preliminary experiment. The chronic toxicity of MISO was enhanced not at all or by a factor of up to 2 for BSO and BSO + DEM respectively. Further studies are needed before it can be concluded that GSH depletion by BSO alone may be a useful adjunct to the clinical use of radiosensitizers.

Isolation and antitumor activity of cyclic hexapeptides isolated from Rubiae radix.

The details of the isolation and antitumor activity of cyclic hexapeptides (RA-VII, RA-V, RA-IV and RA-III) isolated from Rubia cordifolia are reported. Studies on a spectrum of experimental tumors in mice revealed that the peptides exhibited significant activity against leukemias and ascites tumors, P-388, L1210, B-16 melanoma and solid tumors, colon 38, Lewis lung carcinoma and Ehrlich carcinoma. RA-V had an especially potent effect on MM2 mammary carcinoma in mice. The effective dose range of RA-IV against P-388 leukemia was different from those of the other cyclic hexapeptides.

The combination of 5-fluorouracil with misonidazole in patients with advanced colorectal cancer

Misonidazole (MISO) has produced differential enhancement of tumor cell killing with a range of cytotoxic drugs including 5-fluorouracil (FU) in experimental mouse tumors and human xenografts. Since concomitant enhancement of normal tissue damage has been observed, a Phase I study of MISO and FU has been undertaken in patients with advanced colorectal cancer. Mild nausea and vomiting occurred more frequently after MISO and FU compared with FU alone; however, the incidence of leucopenia was similar with both treatments. No patient receiving the MISO/FU combination developed central nervous system toxicity or peripheral neuropathy. Twenty-four hour plasma nitroimidazole kinetics were analyzed and were not modified by the concomitant administration of the cytotoxic drug. Thus, in this preliminary study FU has been safely combined with MISO without significant modification of plasma nitroimidazole pharmacokinetics. Tumor regression was documented in 2 9 (22%) patients receiving more than 2 courses of MISO/FU. A Phase II study is proposed to investigate tumor response.

Effect of crocetin on experimental skin tumors in hairless mice.

Crocetin seems to have a small effect in slowing the development of skin tumors induced in hairless mice by the application of dimethyl-benz-a-anthracene and croton oil. No definite effect is shown on preventing the development of tumors induced by UV-B radiation.

Antitumor activity of 13-methyl-berberrubine derivatives.

The antitumor activity of several 13-alkyl-berberrubine and newly synthesized ester derivatives, using experimental tumors (S-180, NF sarcoma, Ehrlich carcinoma and L-1210) in mice was tested. For chemotherapeutic evaluation, the therapeutic indices and ratios were determined. Our present findings confirmed that in berberrubine derivatives, the 9-demethyl structure was essential for the manifestation of antitumor activity and demonstrated tht ester derivatives also exhibit a remarkable antitumor activity, and the 13-methyl derivatives of both berberrubine and palmatrubine alkaloids showed high antitumor activity.

Evidence for chemical carcinogenesis by multistage process

A well-known two-phase method of inducing experimental skin tumors in mice involves application of a single dose of an "initiator" carcinogen, which probably triggers cell mutation, followed by repeated applications of a weak or totally noncarcinogenic "promoter." But now investigators at the Oak Ridge (Tenn) National Laboratory and Michigan State University, East Lansing, say there is more to the process than that—with perhaps three stages in the promotion phase alone— and that this information may shed light on some possible tumor promoters in humans, and how to inhibit them. Thomas J. Slaga, PhD, of the Oak Ridge facility, told an American Cancer Society seminar in Daytona Beach, Fla, that the first stage of the promotion phase seems to involve induction of primitive stem (embryonic phenotype) cells. This is followed by morphological and biochemical changes in the skin during the second stage, he said, and then by epidermal hyperplasia during what

Tween 80 increases plasma adriamycin concentrations in mice by an apparent reduction of plasma volume

Coadministration of Tween 80 enhances the activity of adriamycin against selected experimental tumors in mice. Although some investigators have suggested a direct effect of Tween 80 on tumor cells, we wished to determine whether altered plasma concentrations of adriamycin occurred which might account for the apparent therapeutic synergism. Male CDF 1 mice were treated i.p. with 6.7 mg/kg of adriamycin alone or combined with 5000 mg/kg of Tween 80 in physiologic saline. Fluorometric determination of adriamycin equivalents in plasma revealed significantly higher adriamycin concentrations 1 and 2 hr post treatment in mice that had received Tween 80. In three separate experiments, a significant, reversible increase in packed cell volume occurred in the peripheral blood of mice treated i.p. with Tween 80. This increase was maximal at 1–2 hr post treatment. The magnitude of the apparent plasma volume reduction accounted quantitatively for the increase in drug concentration.

A simple non-stressful method of heating experimental tumours in unanaesthetised mice

Describes a heating system for hyperthermia of experimental murine tumours. The aim of any heating technique is to achieve a uniform local rise in temperature throughout the tumour. The method described is a form of water heating where the temperature within the tumour rises because of conduction. The tumours treated were implanted subcutaneously on the backs of mice. The advantages of the method, which rapidly achieves uniform intratumour temperature distribution include technical simplicity, absence of stress and in particular the elimination of the need for anaesthetics. In over 400 experiments there has been no mortality as a result of the heating technique.

The disaggregation, separation and identification of cells from irradiated and unirradiated EMT6 mouse tumors

A mixture of enzymes has been used to disaggregate experimental mouse tumor #6 (EMT6) tumors grown in BALB/c mice. Cell yields of 5 × 10 7-10 8 dye-excluding cells per gram of tumor and in vitro clonogenicities of about 10% have been achieved. The STAPUT procedure, which differentiates cells primarily according to size by sedimentation at unit gravity, has been used to separate two main populations of cells, those which are host derived and those which are clonogenic in vitro and in vivo. The separated cells were 45% EMT6, 35% macrophages and 20% lymphocytes. The host cells may have some antitumor (EMT6) properties which can be assayed in vitro. The effects of in vivo radiation have been assayed in vitro. The size distributions of hypoxic tumor cells (those which survive 2000 tad of in vivo irradiation) was similar to well-oxygenated ones and this suggests that EMT6 tumor cells may not be severely hypoxic for long times.

Some ω-(2-amino-6-hydroxy-4-oxo-3,4-dihydro-5-pyrimidinyl) alkanoic acids, their derivatives and analogues

Condensation of 1,1,ω-alkanetricarboxylic acids triethyl esters XIV-XXI with guanidine gave ω-(2-amino-6-hydroxy-4-oxo-3,4-dihydro-5-pyrimidinyl) alkanoic acids I-IV, VI-VIII, XIII of which some were converted to derivatives (ethyl ester V, N-acyl derivatives XI and XII). Similarly, triester XVII gave by condensation with urea or thiourea the analogous 5-substituted derivatives of barbituric acid X, and thiobarbituric acid IX, respectively. The structures of selected compounds of this group (IV, V, IX-XI and XIII) were determined by spectral methods. Of interest, from the pharmacological point of view, has proved compound IV, which exhibited a significant antineoplastic effect on some experimental tumours in mice and rats, and enhanced the action of some current cytostatics.