[New findings on viral etiology on the so-called Yoshida's ascites sarcoma].
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The antitumor activity and enzymology of 2'-deoxy-3', 5'-bis-O-(4-methoxyphenoxycarbonyl)-5-fluoro-3-(4-n-Propoxybenz oyl uridine (FF-707) were examined. It was found that stability in small intestine homogenate of FF-707 was higher than that of FF-705 [2'-deoxy-3', 5'-O-diacetyl-5-fluoro-3-(3 methylbenzoyl) uridine]. Reduction of the tumor weight was greater in mice bearing sarcoma-180 and rats bearing Yoshida sarcoma treated with the oral administration of FF-707 than that FF-705. The relationship between the antitumor activity and the inhibition of thymidylate synthase after the oral administration of FF-707 was examined. The extent of the inhibition of thymidylate synthase seemed to be parallel to that of the inhibition of the tumor growth.
In order to acquire a fundamental knowledge for the development of better tumor-scanning agents, the in vivo incorporation pattern of three 14C-labeled D-amino acids, alanine, leucine, and tryptophan, into the tumor cells and organs of animals bearing Ehrlich mouse tumor, sarcoma-180, leukemia L-1210, or Yoshida sarcoma was investigated, and compared with that of the corresponding L-forms. The radioactivity of D-amino acids tested was most highly found in tumor cells and pancreas, and the activity in tumor cells was several times higher than that of L-forms. A large portion of the radioactivity of D-forms was found in trichloroacetic acid-soluble fraction of the cells, whereas that of L-forms was mostly in protein fraction, except L-alanine. Although the mechanisms whereby the radioactivity of D-amino acids was concentrated more than that of L-forms in the tumor cells have not yet been clearly elucidated, it was concluded that gamma-emitter-labeled D-amino acids themselves or their derivatives might be useful as tumor-detecting radiopharmaceuticals.
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To evaluate the accuracy of in vivo estimates of protein synthesis and breakdown, measurements of plasma and tissue leucine kinetics were made in rat tumor tissues at different conditions of growth by use of constant intravenous infusion of [14C]leucine. These measurements were made in Yoshida sarcoma tumors on days 10 and 13 after implantation, with and without tumor necrosis factor (TNF) infusion and on day 10 in Walker-256 carcinosarcoma. Expressed as micromoles of leucine per gram tissue, tumor protein breakdown increased (P less than 0.01) from 0.32 +/- 0.02 to 0.52 +/- 0.09 (SE) mumol/h, with progress of the Yoshida sarcoma tumor between days 10 and 13 after implantation. Similarly, TNF increased tumor proteolysis on day 10 (0.43 +/- 0.03 mumol.h-1.g-1, P less than 0.05 vs. day 10 control) but not on day 13 after implantation of the Yoshida tumor. Estimates of growth derived from the difference between protein synthesis and breakdown rates were not statistically different from those based on actual tumor volume changes in both tumor models. However, estimates of "whole body" protein metabolism (plasma leucine flux) were not affected either by tumor aging or by treatment with TNF. This study shows that in vivo estimates of tissue protein metabolism based on our [14C]leucine constant infusion model closely reflect the growth characteristic of that tissue. A cytotoxic perfusion-independent effect for intravenous TNF on growing tumor tissue is demonstrable as increased protein breakdown. Furthermore, the commonly used concept of whole body protein metabolism, derived solely from tracer dilution in plasma, is an oversimplification.
1-(2-Chloroethyl)-3-isobutyl-3-(beta-maltosyl)-1-nitrosourea (TA-077) was hydrolyzed to its glucosyl metabolite TA-G by homogenates of guinea pig organs, rabbit VX-2 carcinoma and rat Yoshida sarcoma. The rate of TA-G formation by the kidney was the highest among the tissues examined and that by the diluted blood was undetectably low, reflecting their maltase activities. TA-077 was also hydrolyzed by suspensions of Yoshida sarcoma, AH130 hepatoma, L1210 leukemia, P388 leukemia and DBLA-10/C leukemia cells. The rate of TA-G formation was increased 10 fold by homogenizing the tumor cells. TA-G was taken up by the tumor cells much more efficiently than TA-077, explaining the higher sensitivities of the cultured tumor cells to TA-G than to TA-077. However, neither the maltase activity nor the membrane permeability to the drugs was a factor influential enough to explain the differences in drug sensitivity among the tumor cell lines.
As a part of our studies on the chemical, biochemical and pharmacological characteristics of the newly synthesized antioxidants, nitroxide derivatives, we designed a novel nitroxide, named Tempicol-2. Its capacity to act as antioxidant of potential pharmacological application was tested in three model systems: xanthine/xanthine oxidase, iron- and ascorbate Fenton reaction(s) and gamma-radiolysis. The antioxidant properties of Tempicol-2 as a function of concentration were compared with those previously characterized nitroxide derivatives Tempace and Rutoxyl which we had synthesized. The possibility of one-electron reduction of the novel substance by ascorbic acid was also examined and compared. The ability of Tempicol-2 to act as anticancer agent in vivo was also investigated in pharmacologic tests. The administration of Tempicol-2 to rats bearing 3 day-old Yoshida Sarcoma (promotion phase) led to both growth inhibition and the induction of apoptotic cells(s) death, comparable to the effects of Tempace and Rutoxyl under the same experimental conditions. Our results confirmed the suggested involvement of free radicals in the pathogenesis of model. Yoshida Sarcoma, thus indicating that anticancer activity of the investigated nitroxides may indirectly involve an antioxidant mechanism. The results reported here are encouraging as we find a limited correlation between the molecular redox properties, structure of nitroxides and their antitumor action. Tempicol-2, similarly to Tempace and Rutoxyl, is a promising antioxidant which can induce apoptosis, thus providing the basis for further investigations of the concentration and phase-dependent effects and the exact mechanisms of nitroxide(s) apoptotic action using cell line(s) model.
The blood supply in the central portions of solid Yoshida sarcoma tumors is poor, but these portions contain viable cells capable of tumor growth when transplanted into new hosts. Attempts were made to increase penetration into these portions in rats by an injection of prostaglandin E1 together with lissamine green dye (used as a marker of drug penetration). The lissamine green dye defined the regions which could not readily be reached by blood-borne substances. Next, mitomycin C in place of lissamine green was administered together with prostaglandin E1. The growth of Yoshida sarcoma cells transplanted subcutaneously was suppressed significantly in the rats given mitomycin C with prostaglandin E1 compared with that in the rats given mitomycin C alone. The effect was greater when prostaglandin E1 was administered by an intraarterial route than by an intravenous route (P less than 0.01). Five patients with hepatic metastases from colorectal carcinoma were treated with a one-shot infusion of mitomycin C together with prostaglandin E1. Two patients showed objective evidence of improvement.
Ten new Pt (II) complexes were synthesized and tested as potential antitumor drugs in vitro on KB human tumour cell line, and in vivo against four experimental tumour systems (P388, L1210, ADJ/PC6A and Yoshida sarcoma). The complexes contained two primary amine ligands (cyclopentylamine) with bidentate leaving ligands consisting of nitro-, dinitro- and sulfo-derivatives of phthalic and isophthalic anions. Various complexes showed a good cytostatic effect in vitro with ID50 from 0.29 and 0.99 mcg/ml. The Pt(cpa)2 (5-sulfo-IPA) appeared to be the most effective compound against P388 and L1210 (T/C% 310 and 250 respectively after three 50 mg/Kg i.p. injections) as well as against ADJ/PC6A (ID90 2.8 mg/kg after a single i.p. injection) and Yoshida sarcoma (T/C% 17.5 after a single 50 mg/kg i.p. injection), but the phthalic acid nitro-derivatives were also quite effective. As far as antileukemic effect was concerned, there was a fairly good correlation between the results in vitro and in vivo. Relationships between antitumour activity and pi electronic charge localization on O- atoms of leaving ligands (M.O. Huckel's Calculations) are also discussed.
Transplantation of Yoshida sarcoma (solid type) and Zajdela ascites hepatoma tumors in rats induces a biphasic change in the concentration of the following five acute-phase proteins: alpha-1-acid glycoprotein; alpha-1-antitrypsin; haptoglobin; hemopexin; and ceruloplasmin. These proteins and other plasma proteins were quantitated by two-dimensional immunoelectrophoresis relative to normal serum concentrations. The elevation of most of these acute-phase proteins was greater in the second phase, during which serum levels increased continuously as the tumor burden increased until the animals died. The increase in haptoglobin concentration during the second phase was much higher in rats bearing Yoshida sarcoma than in rats bearing Zajdela tumors. Rats receiving irradiated tumor cells showed neither tumor growth nor second-phase protein changes. Significant increases in uptake of 3H-amino acids by isolated perfused livers of tumor-bearing rats provided evidence for an increase in the hepatic synthesis rates of the acute-phase proteins. Removal of the solid tumor resulted in a gradual decrease of acute-phase protein concentrations with concomitant increase in serum albumin concentration. These alterations in serum acute-phase proteins during tumor growth and after removal of the tumor may make their use attractive as biological markers of the response of the tumor-bearing animal to its tumor.
The biochemical mechanism of the synergy of 5-fluorouracil (FUra) and cisplatin (CDDP) was studied using transplantable tumors in rodents in vivo. The reduced folate 5,10-methylenetetrahydrofolate (CH2FH4) and its precursor tetrahydrofolate (FH4) are essential cofactors for the formation of a tight ternary complex of thymidylate synthase (TS) and 5-fluoro-2'-deoxyuridine-5'-monophosphate (FdUMP) derived from FUra. Intraperitoneal administration of CDDP (5 mg/kg) inhibited the incorporation of exogenous L-methionine into ascitic tumor cells and increased the levels of CH2FH4 and FH4 in ascitic Yoshida sarcoma and P-388 cells transplanted into rats and mice to levels about 2-3 times those measured in cells from animals that were not treated with CDDP. Preincubation with 10(-6) M FUra in Hanks' medium inhibited [6-3H]-2'-deoxyuridine incorporation into DNA of tumor cells from CDDP-treated rats 3 times more than that into cells from untreated rats, indicating that the inhibition of TS by FdUMP derived from FUra was enhanced in the presence of CH2FH4. Intraperitoneal administration of CDDP on day 1 and continuous infusion of FUra from day 1 to day 6 had synergistic effects in inhibiting tumor growth in Yoshida sarcoma-bearing rats. Oral administration of UFT, a combined form of 1 M tegafur and 4 M uracil, for 7 consecutive days beginning at 24 h after tumor implantation and a single i.p. injection of CDDP on day 1 had a significantly greater effect than did either agent alone. These results suggest that CDDP significantly enhances FUra cytotoxicity by inhibiting intracellular L-methionine metabolism and consequently increasing the reduced folate pool in mammalian tumor models in vivo.
Little information is available on proteolytic pathways responsible for muscle wasting in cancer cachexia. Experiments were carried out in young rats to demonstrate whether a small (< 0.3% body weight) tumor may activate the lysosomal, Ca(2+)-dependent, and/or ATP-ubiquitin-dependent proteolytic pathway(s) in skeletal muscle. Five days after tumor implantation, protein mass of extensor digitorum longus and tibialis anterior muscles close to a Yoshida sarcoma was significantly reduced compared to the contralateral muscles. According to in vitro measurements, protein loss totally resulted from increased proteolysis and not from depressed protein synthesis. Inhibitors of lysosomal and Ca(2+)-dependent proteases did not attenuate increased rates of proteolysis in the atrophying extensor digitorum longus. Accordingly, cathepsin B and B+L activities, and mRNA levels for cathepsin B were unchanged. By contrast, ATP depletion almost totally suppressed the increased protein breakdown. Furthermore, mRNA levels for ubiquitin, 14 kDa ubiquitin carrier protein E2, and the C8 or C9 proteasome subunits increased in the atrophying muscles. Similar adaptations occurred in the muscles from cachectic animals 12 days after tumor implantation. These data strongly suggest that the activation of the ATP-ubiquitin-dependent proteolytic pathway is mainly responsible for muscle atrophy in Yoshida sarcoma-bearing rats.
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The cell growth inhibitory effects of prostaglandin D2 (PGD2) were examined on cultured and implanted malignant tumor cell lines. The results were as follows. 1) PGD2 showed significant cytotoxicity against Sarcoma-180, Ehrlich cancer, Yoshida sarcoma and KATO-III in culture. The cytotoxicity of PGD2 against KATO-III was the lowest. 2) PGD2 at a dose of 40 micrograms/mouse/day was intraperitoneally injected into ddY mice for 10 days starting on the first day after an intraperitoneal implant of 2 X 10(5) Sarcoma-180 cells. As a result, the duration of survival was significantly prolonged. However, intravenous injection was less effective than intraperitoneal injection. 3) Addition of Forskolin to the cultured KATO-III cells with PGD2 resulted in a significant increase of cyclic AMP (cAMP) levels. However, the growth inhibition of PGD2 was independent of elevated levels of cAMP. 4) DNA histograms using flow cytometry showed PGD2 blocked significantly G2 + M phase DNA synthesis in the cultured Sarcoma-180 cells, and S phase DNA synthesis in KATO-III cells was significantly blocked with PGD2 at a concentration of 100 micrograms/ml. The results indicate that PGD2 possesses an antitumor effect on 4 malignant tumor cell lines. Furthermore, it seems that the antitumor mechanism of PGD2 is due to the inhibition of DNA synthesis rather than the action through cAMP-receptor, and the blockade to cell cycle progression is dependent on kinds of tumor cell lines.