Isidore Wodinsky

Transport and Phosphorylation as Factors in the Antitumor Action of Cytosine Arabinoside

Survival of mice bearing different transplantable leukemias and treated with cytosine arabinoside was compared with uptake and subsequent phosphorylation of the drug in vitro. Capacity for nucleotide formation was correlated with response and is apparently an important determinant of drug sensitivity. Drug uptake, although apparently mediated, was similar in all cell lines.

Spleen colony studies of leukemia L1210. VI. Quantitation of the surviving population of frozen-thawed L1210 cells using the spleen colony assay.

Summary The spleen colony assay showed that the percentage of viable L1210 cells frozen to −15°C and thawed was similar to that for nonfrozen leukemic cells as estimated by colonyforming units (CFU). At temperatures between −15 and −60°C, the CFU decreased exponentially, demonstrating cellular injury during the freezing or thawing process. The surviving CFU fraction at −60°C was 10% of the nonfrozen controls, and further reduction of the temperature to 195°C resulted in no further increase of cell destruction.

Viability of fifty-five neoplasms after storage in liquid nitrogen.

Abstract Fifty-five neoplasms of mice, rats, and hamsters and of human cell origin have been stored at liquid nitrogen temperature for periods up to 1 year after slow freezing with a Canalco controlled temperature unit. Fifty-three of these tumors have remained viable, and only the Ridgeway osteogenic sarcoma and the 3,4,9,10 dibenzpyrene-induced fibrosarcoma in the random-bred mouse became nonviable. Trypan blue dye exclusion tests on ascites tumors showed an apparent survival of 40 to 95% of the cells after storage, without, however, producing any significant changes in mean survival times when implanted into new hosts. Continuous animal passage revealed changes within 6 months in virulence (increase or decrease in mean survival times) of the Gardner lymphosarcoma, P815 mast cell leukemia, and 70429 plasma cell leukemia, whereas lines from the tumor bank did not demonstrate these changes. Chemotherapeutic tests of 23 neoplasms after storage for 1 year in liquid nitrogen demonstrated that freezing and storage did not affect the sensitivity (or resistance) of these neoplasms to the standard agents tested.

Accumulation of two alkylating agents, nitrogen mustard and busulfan, by murine leukemia cells in vitro.

Abstract The accumulation of two alkylating agents by murine leukemia cells in vitro was studied. Nitrogen mustard (HN 2 ) and busulfan rapidly penetrated cells; cell-medium drug distribution ratios of one were established within 3 min at 0° over a wide range of external drug levels. Accumulation of busulfan was not much affected by raising the incubation temperature. NH 2 binding was, however, a remarkably temperature-sensitive process. At10 −5 M levels, busulfan and HN 2 partly inhibited cellular incorporation of precursors into nucleic acids in vitro . When cell types differing widely in sensitivity to these alkylating agents were tested, no differences in capacity for drug accumulation or in subsequent inhibition of nucleic acid synthesis could be found.

Combination chemotherapy against B 16 melanoma: bleomycin/vinblastine, bleomycin/cis‐diamminedichloroplatinum, 5‐fluorouracil/BCNU and 5‐fluorouracil/methyl‐CCNU

Four antitumor drug combinations which are currently in clinical use were evaluated experimentally using the murine B16 melanoma model. Bleomycin plus vinblastine produced an increase in life span over either of the two agents alone against both intraperitoneal and subcutaneous B16. This combination also resulted in a large number of long‐term survivors. Bleomycin plus cis‐platinum produced slight enhancement against subcutaneous B16, but showed no advantage against intraperitoneal B16. The combination of 5‐fluorouracil plus methyl‐CCNU significantly increased survival time against the intraperitoneal tumor, and produced long‐term survivors as well. The combination of 5‐fluorouracil plus BCNU was not more effective than BCNU or 5‐fluorouracil alone. These data were compared with the degree of success reported from the clinics against a variety of solid human neoplasms. Cancer 42:1711–1719, 1978.

Correlates of vincristine resistance in four murine tumor cell lines

The mechanism(s) of cellular resistance to vincristine (VCR) are poorly understood. Four murine tumor cell lines with varying degrees of VCR resistance, as measured by prolonged survival of tumor-bearing mice following VCR treatment, were selected for study. These lines were P1534, P388, P388/VCR and L1210. Steady-state cellular VCR levels, bound intracellular VCR, displaceable intracellular VCR, influx velocities and efflux velocities following VCR preloading were all measured in vitro and correlated with augmentation of survival. Neither the influx velocity, efflux velocity nor the steady-state VCR level showed any apparent correlation with in vivo sensitivity. Moreover, the ratio of influx velocity to efflux velocity was highest in the most sensitive cell line (i.e. P1534) and lowest in the most resistant cell line (i.e. P388/VCR). Bound intracellular VCR correlated best with VCR sensitivity suggesting that high-affinity intracellular binding, presumably to tubulin (Ka congruent to 1 X 10(-7) M), is a critical determinant of VCR sensitivity.

Combined therapy with an aziridine derivative NSC 200724 (AB182) and radiation on an experimental leukemia

Abstract 0-[bis(2,3-dimethyl-l-aairidinyl)phosphinyl]-N-hydroxyurethane AB182, in combination with irradiation was investigated in the P388 lymphocytic leukemia system. Combined modality effectiveness appeared to be associated with radiation dose and tumor stage. Cytotoxicity studies indicated that the drug alone was cytotoxic and potentiated cell killing when it was used in combination with radiation.

Viability of forty-two neoplasms after long-term storage in liquid nitrogen at −195 °C

Forty-two neoplasms stored at −195 °C for periods up to 6 years have remained transplantable and lethal to their inoculated hosts. A bioassay which estimates the surviving cell population based on the cell kinetics of exponentially growing neoplasms in vivo demonstrated an initial loss of viable cells due to the freezing procedures and no further losses due to storage. The response of 14 drug-induced resistant neoplasms to chemotherapeutic agents has remained unaltered after long-term storage.

The strain specificity of transplantable neoplasms after freezing and storage in liquid nitrogen

Summary Seventeen tumors of lymphomatous origin were frozen and stored for 20 to 24 months in liquid nitrogen. Leukemia L1210/MTX and leukemia P388/38280 demonstrated an increase in histocompatibility crossing strain barriers. Lymphoma 2, L5178Y, P1081, P288/MTX, and P1534 CDF 1 grew in fewer strains when the cell inoculum was lowered. L1210, L1210/38280, P388, P388/57155, P388/VCR, AK, P329, Lymphoma 4, P815, and RCS remained strainspecific.

The effect of suramin-phthalanilide complexes on the chemotherapeutic activity and toxicity of 4′,4″-bis (1,4,5,6-tetrahydro-2-pyrimidinyl)terephthalanilide (NSC 57153)

Abstract Suramin forms water-insoluble complexes with 4′,4″- bis (1,4,5,6-tetrahydro-2-pyrimidinyl)terephthalanilide (NSC 57153). The mole ratio of Suramin-drug for maximum complex formation is 0·3:1 . Excess Suramin dissolves this precipitate whereas excess drug does not. The uptake of NSC 57153 by P815 mast cell leukemic cells in vitro is affected by the presence of Suramin. Excess moles of Suramin relative to drug inhibit uptake, whereas excess moles of drug enhance the uptake. Although Suramin administration has no effect on drug uptake by tumor cells in vivo and does not affect the antileukemic activity of NSC 57153, it does delay the onset of NSC 57153 toxicity in mice. Three drug components (lipid-bound, hydrophilic-bound, and “free” drug) are extracted from tumor cells and the ratio of the three drug components is not affected by the extracellular Suramin-drug ratios after the cells have been exposed to drug either in vitro or in vivo . Suramin lowers the concentration of NSC 57153 in both kidney and liver but not in muscle. The drug is extracted primarily as a lipid complex from all tissues, whether the animals have been treated with NSC 57153 or with Sumarin-NSC 57153 complexes.