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An autoradiographic study of the binding of 3-H-chlorambucil to cells of a drug-sensitive and drug-resistant strain of the Yoshida ascites sarcoma.

The binding of chlorambucil to drug-sensitive and drug-resistant. Yoshida sarcoma cells has been investigated by an autoradiographic technique. The cells were treated with the drug at various concentrations both in vitro and in vivo. Using both light and electron microscope techniques, and by counting grains on various areas of the cell, the following conclusions were reached. (1) At all drug concentrations there was general cytoplasmic and nuclear uptake by both cell lines. There was no evidence of a specific localization in one site only or for specific exclusion of any one site. (2) At high dose levels (equivalent to 2 mM) the binding was approximately equal in both cell lines, although a few damaged cells bound much greater amounts of drug. (3) At low dose levels (equivalent to 3 mu-M) there was a higher uptake by the nucleus of the sensitive cells compared with the nucleus of the resistant cells; the cytoplasmic binding was similar.

Animals↗

Selective targeting of magnetic albumin microspheres containing low-dose doxorubicin: total remission in Yoshida sarcoma-bearing rats.

Magnetically responsive albumin microspheres containing doxorubicin hydrochloride were selectively localized in Yoshida sarcoma tumors. Tumors were implanted subcutaneously in the tail of Holtzman rats and allowed to grow to at least 200 mm2 size before initiation of experimental treatment. Drug-bearing microspheres at a dose level of either 0.5 or 2.5 mg/kg were infused proximal to the tumor via the ventral caudal artery. A bipolar permanent magnet was placed adjacent to the tumor during the infusion to effect localization. Control animals were treated with free doxorubicin infused intra-arterially at 5.0 mg/kg or 0.5 mg/kg. In other test groups animals received placebo microspheres localized in the tumor via influence of the external magnetic field, or drug-containing microspheres were infused without utilization of the magnet to effect localization. Of the 22 animals receiving magnetically localized doxorubicin microspheres 17 had total histological remission of the tumor. The remaining animals demonstrated marked tumor regression representing as much as 500-600 mm2 decrease in tumor size. While no deaths or metastases occurred in the groups receiving localized drug, animals treated with free doxorubicin, placebo microspheres or non-localized doxorubicin microspheres exhibited a significant increase in tumor size with metastases and subsequent death in 90-100% of the animals. No significant differences were noted in tumor regression/remission data between the 0.5 and 2.5 mg/kg dose levels of magnetically localized doxorubicin spheres. These results represent a significant advance in targeted chemotherapy in that 77% of the animals in the magnetically localized doxorubicin microsphere treatment groups exhibited total remission after only one regimen of drug therapy.

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Further studies on the cytochemistry of the standardized silver staining of interphase nucleoli in smear preparations of Yoshida ascitic sarcoma cells in rats.

Silver staining procedure for the selective demonstration of nucleolar silver stained granules (SSG) and for the simultaneous demonstration of SSG and nucleolar silver stained matrix (SSM) were studied in smears of rat Yoshida sarcoma cells. The successful results of these procedures depend mainly on the quality of silver nitrate and formaldehyde. However, both chemicals can be easily standardized and stabilized disregarding their origin and batch. In standardized procedures (one-step procedure for the selective demonstration of SSG and two-steps procedure for the simultaneous demonstration of SSG and SSM) the silver is apparently bound to acidic groups of proteins of SSG and SSM. The proteins of SSG and SSM seem to be different but both belong to the group of acidic non-histone proteins. According to the results of digestion experiments a possibility also exists that the acidic proteins of SSG may be associated with DNA. The identification of SSG visualized by described standardized procedures was determined not only by cytochemical extraction tests but also by biological experiments. The latter demonstrated that the number of SSG in Yoshida sarcoma cells decreases after treatment of experimental animals with actinomycin D and therefore depends on the state of the nucleolar RNA synthesis.

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Some effects of chlorambucil on nuclear protein phosphorylation in the Yoshida ascites sarcoma.

The ability of nuclei, isolated from Yoshida ascites sarcoma cells, to phosphorylate nuclear proteins in the presence of [gamma-32P]ATP has been investigated. Comparisons were made between a strain sensitive to the effects of the alkylating agent, chlorambucil, with a corresponding resistant strain both before and after drug-treatment of tumour-bearing animals. There was no gross quantitative differences between the drug-sensitive and-resistant untreated cells but treatment resulted in increased levels in the sensitive strain. Qualitative differences were seen before treatment in the phosphorylation pattern of the tris-saline-soluble nuclear sap fraction. The high molecular weight species in the fraction from sensitive cells showed phosphorylations which were absent, or present at very low levels, in the corresponding fraction from drug-resistant cells. Changes were observed in the tris-saline-soluble and non-histone protein fractions from drug-sensitive cells following treatment of tumour-bearing animals. Only minor alterations in patterns of phosphorylation were seen in fractions from drug-resistant cells.

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Tumor remission in Yoshida sarcoma-bearing rts by selective targeting of magnetic albumin microspheres containing doxorubicin.

Magnetically responsive albumin microspheres containing doxorubicin and magnetite (Fe3O4) were selectively targeted to Yoshida sarcoma tumors in rats by utilizing an extracorporeal magnet. Tumor cells were inoculated subcutaneously in the tail of rats, and the tumors were allowed to grow to an average size of 9 X 45 mm prior to initiating treatment. Drug-bearing microspheres (0.5 mg of doxorubicin per kg of body weight) were infused proximal to the tumor through the ventral caudal artery while the tumor was exposed to an external magnetic field of 5500 Oe for 30 min. Control animals received free doxorubicin administered either intravenously (5 mg/kg) or infused intraarterially (5 and 0.5 mg/kg), drug-bearing microspheres infused intraarterially (0.5mg/kg), without the external magnet, or placebo microspheres with magnetic localization. Of the 12 animals treated with a single dose in the experimental group, 9 exhibited total remission of the tumor, representing a disappearance of tumors as large as 60 mm in length. Marked tumor regression was observed in the remaining three rats, and no deaths or metastases occurred in the experimental group. In contrast, significant increases in tumor size with widespread metastases occurred in all control groups and most rats died. These experiments indicate that targeting of oncolytic agents to solid neoplasms by magnetic microspheres may be a means of increasing the efficacy and decreasing the toxicity of antitumor agents.

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Antitumor effect of methionine-depleting total parenteral nutrition with doxorubicin administration on Yoshida sarcoma-bearing rats.

Methionine-depleting total parenteral nutrition (methionine-depleting TPN), which infuses an amino acid solution devoid of L-methionine and L-cysteine as the sole protein source, showed enhancement of the effect of several anti-cancer agents. In this study, the combined effect of the methionine-depleting TPN with the administration of doxorubicin was examined in Yoshida sarcoma (YS)-bearing rats with regard to effects on the primary tumor growth, the extension of metastasis, and the host animal's life span. In the first experiment, immediately after receiving methionine-depleting TPN for 8 days, the animals were killed. Pathologic findings evaluated tumor growth in the implanted site and extension of the metastasis. In the second experiment, the survival period was determined after animals received methionine-depleting TPN for 10 days, with subsequent oral feeding until they died naturally. Proliferation of YS was markedly suppressed. In particular, hematogenous metastasis, which is a characteristic of YS, was suppressed, and a longer survival period (42.7 +/- 15.6 days, mean +/- SD) was attained in rats in the group treated with the methionine-depleting TPN combined with the administration of doxorubicin.

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Anti-tumor effect of L-methionine-deprived total parenteral nutrition with 5-fluorouracil administration on Yoshida sarcoma-bearing rats.

L-methionine-deprived total parenteral nutrition (methionine-deprived TPN), infusing amino acid solution devoid of L-methionine and L-cysteine by the method of TPN as an only protein source, showed enhancement of the effect of several anti-cancer agents. In this study the combined effect of the methionine-deprived TPN with administration of 5-fluorouracil (5-FU) was examined in Yoshida Sarcoma (YS)-bearing rats, from aspects of effects on the tumor metastasis and the host animal's life span, in the following four groups treated with: methionine-deprived TPN with administration of 5-FU, methionine-deprived TPN without administration of 5-FU, L-methionine-contained TPN plus 5-FU, and L-methionine-contained TPN without 5-FU. In the first experiment, TPN was continued for 8 days in the four groups, and the anti-cancer effect of methionine-deprived TPN and administration of 5-FU based on both the growth of the primary tumor at the implanted site and the tumor metastasis was studied from the view point of pathologic findings of animals killed immediately after these treatments. In experiment 2 the survival period was examined after these treatments for 10 days with subsequent oral feeding until death. The results were as follows: proliferation of YS, transplanted subcutaneously, was markedly suppressed; particularly hematogenous metastasis, characteristic in YS, was prominently blunted then obtained an apparent longer survival period in rats treated with the methionine-deprived TPN with administration of 5-FU.

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Separation of cytidine diphosphate reductase from rat Yoshida ascites sarcoma.

CDP reductase was separated from the cytosol of rat Yoshida ascites sarcoma. The precipitate, which resulted from the acidification of the cytosol by acetic acid at pH 5.2, catalyzed specifically the reduction of CDP, whereas the concurrently resulted supernatant catalyzed those of UDP, ADP and GDP. The CDP reductase showed a single peak in the pattern of the enzyme activity in DEAE-cellulose and also in Sepharose 4B column chromatography with adequate recovery of the activity.

Animals↗

Origin of increased deoxycytidine excretion into urine of rats bearing Yoshida ascites sarcoma.

The metabolism of deoxycytidine (dCyd) and dCyd nucleotides in Yoshida ascites sarcoma (YS) cells and the host rat liver was investigated with reference to the increased excretion of urinary dCyd. Incorporation of [14C]orotic acid into the livers of rats at the fifth day after the transplantation of YS cells, the time when the amount of excretion of dCyd in urine was near maximal, was 2 times higher than that into the normal rat livers. After the injection of [14C]orotic acid, the ratio of the specific radioactivity of cytidylate to uridylate moieties of the host liver RNA was measured and found to be higher than that of normal rat liver RNA and to be similar to that of YS cell RNA. When [14C]orotic acid was injected into rats followed by the transplantation of YS cells, the radioactivities present in the livers disappeared more rapidly than those in the control rat livers. The activities of pyrimidine de novo synthesis enzymes, such as cytidine triphosphate synthetase (EC 6.3.4.2) and cytidine diphosphate reductase (EC 1.17.4.1), in YS were higher than those in both rat ascites hepatoma AH 7974 and Walker 256 carcinosarcoma, the transplantations of which did not induce increased excretion of dCyd into urine of the hosts. The activities of dCyd kinase (EC 2.7.1.10) and dCyd deaminase (EC 3.5.4.5) in YS cells were lower than those in the other two tumors investigated. The activities of cytidine triphosphate synthetase and cytidine diphosphate reductase in the livers of YS-bearing rats were elevated compared with those in the livers of rat ascites hepatoma AH 7974- or Walker 256 carcinosarcoma-bearing rats and normal rats, while the activities of dCyd kinase, 5'-nucleotidase (EC 3.1.3.5), and dCyd deaminase were similar between normal rat livers and tumor-bearing rat livers. These results suggest that the increased excretion of urinary dCyd in YS-bearing rats could be caused by both the stimulation of the synthesis of dCyd nucleotides and the low activity of dCyd deaminase in YS cells as well as in the host liver.

Animals↗

The binding of [3H]chlorambucil to nuclear proteins of the Yoshida ascites sarcoma.

The binding of [3H]chlorambucil to nuclear proteins, extracted from Yoshida ascites sarcoma cells at 6 h and 24 h after administration of 3H-labelled drug to tumour-bearing animals, has been examined. Both covalent and non-covalent binding was detected. Considerably more drug was found associated with the proteins isolated from the tumour sensitive to the effects of the drug compared with similar proteins isolated from the tumour with an acquired resistance to the effects of alkylating agents. The two-fold difference in binding to total cell protein is attributed to a higher intranuclear protein binding in sensitive cells. In particular the soluble nuclear sap fraction from sensitive cells bound at least five times as much drug as the corresponding fraction from resistant cells. Low levels of binding to histones were demonstrated compared with that to the non-histone chromatin proteins. Binding to the nuclear sap and non-histone chromatin proteins was principally to high molecular weight protein species; these did not appear to represent aggregation products as scans of stained polyacrylamide gels of the extracted protein fractions were unaltered by the treatment of tumour-bearing animals with chlorambucil. Binding to the nuclear proteins from sensitive cells tended to persist over a 24-h period, whereas it was considerably reduced in resistant cells.

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Tumor-host metabolic relationships: total levels and chromatographic pattern of vitamin B12 in serum, liver and tumor of Yoshida sarcoma-bearing rats.

Total content of cobalamins was estimated by an isotopic dilution technique in serum and liver of Yoshida sarcoma-bearing rats and in a group of control rats. Total levels of vitamin B12 were also measured in neoplastic tissue. Hydroxycobalamin, adenosylcobalamin, cyanocobalamin and methylcobalamin, were estimated by a chromato-bioautographic technique in the above mentioned tissues and animals. We found no significant difference between control and tumor-bearing rats with respect to the total content of vitamin B12 in the different tissues. This suggests that vitamin B12 requirements of neoplastic cells do not significantly deplete host cobalamin stores. We have also found no significant differences in the values of the different cobalamin coenzyme forms between the two groups of animals. This suggests that there is not preferential uptake of any host cobalamin fraction by the neoplastic cells. The four coenzyme-forms of cobalamin have been detected in Yoshida sarcoma. Adenosylcobalamin and cyanocobalamin are the major components of the pool of cobalamins of the tissue.

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Cytochemical and immunocytochemical characterization of Yoshida ascites sarcoma cells.

Some cytochemical and immunocytochemical investigations were carried out on actively growing Yoshida ascites sarcoma cells. These cells displayed an intense granular alpha-naphthylacetate esterase (ANAE) staining while the alpha-naphthylbutyrate esterase (ANBE) reaction was in part fluoride-sensitive and marked particularly in the large-size malignant cells. Acid phosphatase as well as peroxidase activities were not detected. The lack of immunoreactive lysozyme and alpha 1-antitrypsin suggested a poor differentiation of the above-mentioned tumor cells, but fibronectin and S-100 protein where highly expressed, as in tumors arising from the mononuclear phagocyte system.

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