tiazofurin and Lung-Neoplasms

We investigated the effect of Tiazofurin (TR-2-beta-D-furanosylthiazole-4-carbamide) on tumour cell invasion using metastatic 3LL-HH murine lung carcinoma and HT168-M1 human melanoma as experimental models. TR pretreatment of 3LL-HH cells, in a dose range of 15-60 microM, caused inhibition of cell proliferation, adhesion to plastic and extracellular matrix proteins. The TR-induced altered matrix interactions of 3LL-HH cells were reflected in decreased migration through matrix-covered filters. Analysis of the expression of certain invasion markers indicated that TR suppressed the expression of alpha v beta 3 integrin and MMP2 metalloproteinase. Biochemical studies indicated that 24 h 60 microM TR treatment of 3LL-HH cells inhibited glycosylation of a wide range of glycoproteins with the most pronounced effect on proteoglycans. TR pretreatment of 3LL-HH tumour cells resulted in the loss of lung colonisation potential in vivo. Furthermore, in vivo TR treatment inhibited the formation of liver metastases of 3LL-HH murine carcinoma. TR treatment also induced inhibition of integrin and MMP2 expression, migration and liver colonisation of the human melanoma HT168-M1 cell line. Since the TR concentration which inhibited various cellular functions was much lower for cell adhesion and lung colonisation than for cell proliferation, we suggest that the predominant effect of TR is the inhibition of metastasis in these model systems. We also suggest that both the effect of TR on tumour cell proliferation and on extracellular matrix interaction contribute to its remarkable antimetastatic potential in vivo.

Topics: Amino Acid Sequence; Animals; Antimetabolites, Antineoplastic; Cell Adhesion; Cell Movement; Dose-Response Relationship, Drug; Flow Cytometry; Glycoconjugates; Humans; Liver Neoplasms; Lung Neoplasms; Mice; Mice, Inbred C57BL; Molecular Sequence Data; Neoplasm Invasiveness; Neoplasm Transplantation; Neoplasms; Ribavirin; Tumor Cells, Cultured

Since taxol (NSC 125975) and tiazofurin (NSC 286193) attack at two different sites in microtubular synthetic processes, we tested the rationale that the two drugs might be synergistic in human ovarian (OVCAR-5), pancreatic (PANC-1) and lung carcinoma (H-125) cells and in rat hepatoma 3924A cells. In human OVCAR-5, PANC-1, H-125 and rat 3924A cells, for taxol the anti-proliferative IC50 was 0.05, 0.06, 0.03 and 0.04 microM, respectively; for tiazofurin IC50 = 8.3, 2.3, 1.8 and 6.9 microM. Thus, the concentrations for taxol required for IC50 for inhibiting cell proliferation were 166-, 38-, 60- and 173-fold lower than those for tiazofurin. Taxol and tiazofurin proved synergistic in all four cell lines tested. The synergism of taxol with tiazofurin should have implications in the clinical treatment of human solid tumors with particular relevance to ovarian, pancreatic, lung and hepatocellular carcinomas.

Topics: Animals; Antineoplastic Agents; Antineoplastic Agents, Phytogenic; Carcinoma; Carcinoma, Adenosquamous; Cell Division; Drug Screening Assays, Antitumor; Drug Synergism; Female; Guanosine Diphosphate; Guanosine Triphosphate; Humans; Liver Neoplasms, Experimental; Lung Neoplasms; Ovarian Neoplasms; Paclitaxel; Pancreatic Neoplasms; Rats; Ribavirin; Spindle Apparatus; Tumor Cells, Cultured

The authors studied the metastasis-inhibiting effect of various dosages of tiazofurin in mice inoculated with a low (LLT) and a highly (LLT-HH) metastatic variant of the Lewis lung carcinoma. The tumor cells were inoculated intravenously (lung colony assay), intramuscularly (muscle-lung metastasis model), and intrasplenically (spleen-liver metastasis model), respectively. In the lung colony assay the tiazofurin proved to be curative. In the muscle-lung and the spleen-liver model the tiazofurin treatment, started after the removal of the parent tumor, drastically decreased the number of metastases in both model systems and brought about a significant prolongation of the survival time in the spleen-liver model. Authors suggest that tiazofurin as one of the most promising candidates for metastasis prevention and inhibition in human beings, too.

Topics: Animals; Antineoplastic Agents; Drug Screening Assays, Antitumor; Lung Neoplasms; Mice; Models, Biological; Neoplasm Metastasis; Ribavirin; Ribonucleosides; Tumor Cells, Cultured

Fourteen evaluable patients with small cell bronchogenic carcinoma received tiazofurin, an inhibitor of inosine monophosphate dehydrogenase, that progressed after one combination chemotherapy. No objective remission was observed at the dosage of 800 mg/m2 for 5 consecutive days. Toxicity was moderate.

Topics: Adult; Aged; Antineoplastic Agents; Carcinoma, Bronchogenic; Carcinoma, Small Cell; Drug Evaluation; Female; Humans; Lung Neoplasms; Male; Middle Aged; Ribavirin; Ribonucleosides

Lewis lung carcinoma (LLC) induces a range of hemopoietic alterations in its murine host including progressive anemia, thrombocytopenia, splenomegaly, neutrophilia, and marrow and splenic myeloid hyperplasia. Concentrations of both pluripotent and committed marrow hemopoietic progenitors is increased and the cycling fraction of granulocyte-macrophage progenitors is accelerated. We have developed a way to study whether these hemopoietic effects become long-term consequences of cancer, using LLC-bearing mice with advanced tumor treated with the antineoplastic agent tiazofurin, 2-beta-D-ribofuranosyl-thiazole-4-carboxyamide, NSC 286193 (TZ). LLC mice were treated with a single dose of TZ either 150, 300, or 600 mg/kg, intraperitoneally on day 6 posttumor implant when lung metastases are present and all hemopoietic effects of the tumor are recognizable. Even a single dose of 150 mg/kg of TZ produced a significant survival advantage, and 600 mg/kg resulted in 30% of the animals remaining disease free during a 5-month follow-up. A 6-week treatment schedule was devised, administering TZ intraperitoneally, 600 mg/kg, weekly beginning on day 6. In this group, median survival was not reached after 9 months of follow-up. The only evidence of myelotoxicity produced by intermittent administration of TZ was a mild anemia which was fully reversible 2 weeks after discontinuance of the drug. No difference in white blood cell count, differential count, or platelet count was detected in tumor bearers and controls treated with TZ. Both pluripotent and committed marrow hemopoietic precursors remained unchanged in TZ-LLC, TZ-controls and untreated controls throughout treatment and 2 weeks thereafter. This study demonstrates that TZ-cured LLC mice are suitable to explore late hemopoietic effects of cancer.

Topics: Animals; Antineoplastic Agents; Bone Marrow; Hematopoietic Stem Cells; Hematopoietic System; Lung Neoplasms; Male; Mice; Mice, Inbred C57BL; Neoplasms, Experimental; Ribavirin; Ribonucleosides

An established in vitro cell line (LLTC), originally derived from the Lewis lung carcinoma (LL), was found to have lost sensitivity to the C-nucleoside antitumor agent tiazofurin (NSC-286193; 2-beta-D-ribofuranosylthiazole-4-carboxamide) both in vitro and in vivo. A new in vitro cell line (LLAK) was derived from LL and compared to LLTC in its growth properties and sensitivity to tiazofurin. LLAK resembled the in vivo tumor in having both a high S-phase fraction and a high rate of cell death at high cell density. In continuous drug exposure growth inhibition assays, the concentration of tiazofurin required to reduce the number of cells in a culture by 50% with respect to control cultures was 0.51 microM for LLAK, 2.6 microM for LLTC, and greater than 10 microM for a range of human cancer cell lines. In cytotoxicity assays involving a 2-hour drug exposure followed by clonogenic assay, tiazofurin was more toxic to LLAK cells than to LLTC cells or L1210 murine leukemia cells, consistent with its high in vivo activity against LL. MM-96 human melanoma cells were highly resistant. Flow cytometry studies indicated that tiazofurin selectively depleted the LLAK cell population of S- and G2-phase cells. In one experiment involving 16 consecutive in vitro passages of LLAK in the absence of tiazofurin, a new line emerged that was resistant to tiazofurin in the clonogenic assay. The results demonstrate the spontaneous emergence of resistance from a tiazofurin-sensitive cell line. If similar processes occur during adaptation of human tumor cells to culture, this may explain the finding of low activity of tiazofurin toward a range of human tumor cell lines.

Topics: Animals; Cell Line; Clone Cells; Colony-Forming Units Assay; Drug Resistance; Flow Cytometry; Humans; Lung Neoplasms; Mice; Mice, Inbred C57BL; Ribavirin; Ribonucleosides; Tumor Stem Cell Assay

The antitumor activity of the antineoplastic agent, tiazofurin (2-beta-D-ribofuranosylthiazole-4-carboxamide), has previously been shown to require intracellular anabolism of the drug to a nicotinamide adenine dinucleotide (NAD) analog (2-beta-D-ribofuranosylthiazole-4-carboxamide adenine dinucleotide or "tiazofurin adenine dinucleotide"), which then acts as a potent inhibitor of the target enzyme inosine monophosphate (IMP) dehydrogenase. Inhibition of the latter enzyme in turn brings about a profound depletion of intracellular guanosine nucleotides essential for tumor cell growth and replication. In the present study, the cytotoxicity and metabolism of tiazofurin have been examined in six human lung cancer cell lines. At the pharmacologically attainable drug concentration of 100 microM, colony survival was less than 1.5% in three cell lines ("sensitive"), while survival in the remaining three was greater than 50% ("resistant"). The metabolism of tritiated tiazofurin was examined at concentrations ranging from 0.5 to 100 microM following both brief (6 h) and protracted (14 d) exposures. The sensitive lines accumulated concentrations of tiazofurin adenine dinucleotide that were approximately 10 times those achieved by the resistant lines at both time points. We also observed tendencies for the sensitive cell lines to exhibit: (a) higher specific activities of NAD pyrophosphorylase, the enzyme required for the synthesis of tiazofurin adenine dinucleotide, (b) significantly lower levels of a phosphodiesterase which degrades the latter dinucleotide, (c) greater inhibition of the target enzyme IMP dehydrogenase, and (d) greater depressions of guanosine nucleotide pools after drug treatment. By contrast, the basal levels of IMP dehydrogenase and purine nucleotides in these six lines did not correlate in any obvious way with their responsiveness or resistance. The accumulation and monophosphorylation of parent drug were also not prognostic variables. These studies thus suggest that the extent of accumulation of tiazofurin adenine dinucleotide, as regulated by its synthetic and degradative enzyme activities, is the single most predictive determinant of the responsiveness of cultured human lung tumor cells to tiazofurin.

Topics: Adenine Nucleotides; Antineoplastic Agents; Cell Line; Cells, Cultured; Cytotoxicity Tests, Immunologic; Humans; IMP Dehydrogenase; Lung Neoplasms; Purine Nucleotides; Pyrimidine Nucleotides; Ribavirin; Ribonucleosides; Sepharose; Tumor Stem Cell Assay

The purpose of this investigation was to examine factors which regulate the reprogramming of gene expression in tumors responsible for resistance to tiazofurin. To study the resistance phenomenon drug-induced tumor lines were selected and examined for the mechanism of resistance. A comparison of the biochemical expression of resistance to tiazofurin in drug-induced resistant lines of hepatoma 3924A, leukemias L1210 and P388 revealed that the 3 lines expressed similar genetic alterations related to reduced TAD content, decreased NAD pyrophosphorylase activity and increased synthesis of guanylates from salvaging preformed guanine indicating that these 3 factors play an important role in the resistance to tiazofurin. Resistance was stable in the leukemia lines and did not require drug to maintain resistance. Hepatoma 3924A resistant line reverted to sensitive state in the absence of drug selection pressure. NAD pyrophosphorylase activity was substantially deleted in the tiazofurin resistant leukemia lines, but was only significantly decreased in the hepatoma resistant line. Extensive biochemical alterations including enhanced activity of IMP dehydrogenase, increased inosinate and guanylate pools, and reduced uptake of tiazofurin were found in the hepatoma line resistant to tiazofurin. To examine the applicability of these results to naturally sensitive and spontaneously resistant tumors, murine tumors were examined. In murine tumors, TAD accumulation, ratios of enzyme activities responsible for the synthesis and degradation of TAD, and the ratios of perturbation of inosinate and guanylate pools following tiazofurin challenge demonstrated significant correlation with the sensitive or resistant nature of the tumors. To extrapolate these observations to human tumor systems, cytotoxicity of tiazofurin and its metabolic effects were compared in 6 human lung cancer cell lines derived from cancer patients with small cell lung cancer (4 lines) and lung adenocarcinoma (2 lines). Cell lines exhibiting greater sensitivity to tiazofurin accumulated significantly larger amounts of TAD and showed significant reduction of guanylate pools following tiazofurin incubation. The activity of the enzyme responsible for the formation of TAD, NAD pyrophosphorylase, did not correlate with responsiveness to tiazofurin but the enzyme which hydrolyzes TAD, TADase, correlated positively with the status of resistance.(ABSTRACT TRUNCATED AT 400 WORDS)

Topics: Adenine Nucleotides; Animals; Antineoplastic Agents; Cell Line; Cell Survival; Drug Resistance; Guanine Nucleotides; Humans; Inosine Nucleotides; Leukemia L1210; Leukemia P388; Liver Neoplasms, Experimental; Lung Neoplasms; Mice; Nicotinamide-Nucleotide Adenylyltransferase; Rats; Ribavirin; Ribonucleosides

A detailed study of the inhibition of DR and TR in the SkLu-1 line of human lung adenocarcinoma has shown that TR significantly inhibits this tumor line, probably via inhibition of IMP dehydrogenase by the corresponding TAD analog of NAD. DR exhibited a similar degree of inhibition in this cell line. In a system devised to detect the inhibition of cloning efficiency of the SkLu cells, DR showed a 50% inhibition at 4 X 10(-3) M and TR at 1 X 10(-4) M. When DR and TR were used in combination, the ID50 was decreased to 3 X 10(-5) M. The study of DR in a number of human carcinoma cell lines revealed that de novo purine biosynthesis was significantly inhibited; however, in the SkLu-1 lung carcinoma cells this inhibition was not observed. The synergism observed in this cell line is presently viewed as potentially due to both agents acting on IMP dehydrogenase at different sites.

Topics: Adenocarcinoma; Antineoplastic Agents; Cell Division; Cell Line; Clone Cells; Drug Synergism; Formates; Guanosine; Humans; Lung Neoplasms; Purines; Ribavirin; Ribonucleosides

Treatment of 2,3,5-tri-O-benzoyl-beta-D-ribofuranosyl-1-carbonitrile with hydrogen selenide provided 2,5-anhydro-3,4,6-tri-O-benzoyl-D-allonselenoamide (3). Compound 3 was treated with ethyl bromopyruvate to provide ethyl 2-(2,3,5-tri-O-benzoyl-D-ribofuranosyl)selenazole-4-carboxylates, which after ammonolysis were converted to 2-beta-D-ribofuranosylselenazole-4-carboxamide (6) and its alpha-analogue 7, respectively. Acetylation of nucleoside 6 provided 2-(2,3,5-tri-O-acetyl-beta-D-ribofuranosyl)selenazole-4-carboxamide, and phosphorylation of 6 provided the corresponding 5'-phosphate 9. Compounds 6 and 9 were found to be cytotoxic toward P388 and L1210 cells in culture and effective against Lewis lung carcinoma in mice.

Topics: Animals; Antineoplastic Agents; Chemical Phenomena; Chemistry; Lung Neoplasms; Mice; Ribonucleosides; Selenium

Topics: Animals; Antineoplastic Agents; Carcinoma, Bronchogenic; Lung Neoplasms; Mice; Neoplasm Metastasis; Neoplasm Transplantation; Neoplasms, Experimental; Ribavirin; Ribonucleosides