The antitumour activity of alkylating agents is not correlated with the levels of glutathione, glutathione transferase and O6-alkylguanine-DNA-alkyltransferase of human tumour xenografts. EORTC SPG and PAMM Groups.

Twenty-three human xenografts, including five colon, five gastric, nine lung (three small cell lung cancer) and four breast carcinomas, were investigated for their sensitivity to nitrosoureas, dacarbazine (DTIC), cyclophosphamide (CTX) and cisplatin (DDP). In 12 cases, at least one of the drugs produced complete or partial remission, in 2, a minor regression was observed and in the other 9, treatment was ineffective. The level of sensitivity to each drug, using a score from 1 to 5, was correlated to three biochemical parameters reported to be involved in resistance to alkylating agents: glutathione (GSH), glutathione transferase (GST) and O6-alkylguanine-DNA-alkyltransferase (AGT).

Characterization of cyclin B1 expression in human cancer cell lines by a new three-parameter BrdUrd/cyclin B1/DNA analysis.

Flow cytometric cyclin expression/DNA content analysis, now commonly used, provides useful information on the mechanisms regulating cell cycle progression. However, this biparametric analysis does not make a clear-cut distinction between G1 and S-early or between S-late and G2M phase cells. This paper proposes a new three-parameter flow cytometric method with which to determine cyclin B1 levels in single cells in different cell cycle phases by coupling bromodeoxyuridine (BrdUrd) immunodetection and DNA content.

Treatment with inhibitors of polyamine biosynthesis, which selectively lower intracellular spermine, does not affect the activity of alkylating agents but antagonizes the cytotoxicity of DNA topoisomerase II inhibitors.

Inhibitors of ornithine decarboxylase (ODC), such as alpha-difluoromethylornithine (DFMO), may influence the cytotoxicity of anti-tumour agents that interact with DNA. Intracellular levels of putrescine and spermidine were markedly reduced by ODC inhibitors while the level of spermine, which is the main polyamine in nuclei, was unchanged. By combining a novel inhibitor of ODC, such as (2R, 5R)-6-heptyne-2,5-diamine (MDL 72.

Comparison of cell-cycle phase perturbations induced by the DNA-minor-groove alkylator tallimustine and by melphalan in the SW626 cell line.

Tallimustine or N-deformyl-N-[4-N-N,N-bis(2-chloroethylamino)benzoyl], a distamycin-A derivative (FCE 24517), is a novel anti-cancer agent which alkylates N3 adenine in the minor groove of DNA. The cell-cycle phase perturbations induced by the drug were investigated and compared with those caused by melphalan (L-PAM) in SW626 human ovarian-cancer cells. By coupling bromodeoxyuridine (BUdR) immunoreaction with biparametric flow-cytometric (FCM) analysis, we investigated the cell-cycle phase perturbation induced by tallimustine or L-PAM, considering separately the cells which, during the 1-hr treatment, were in the S phase or in G1-G2/M phases of the cell cycle.

Intracellular glutathione heterogeneity in L1210 murine leukemia sublines made resistant to DNA-interacting anti-neoplastic agents.

Intracellular glutathione (GSH) content was measured by flow cytometry using monochlorobimane (mBCl) and by the enzymatic assay in a set of 6 sublines of murine L1210 leukemia cells made resistant to DNA-interacting agents having distinct mechanisms of action: L-phenylalanine mustard (L-PAM), 1,3-bis(2-chloroethyl)-I-nitrosourea (BCNU), cisplatin (DDP), N-deformyl-N-(4-N,N-bis(2-chloroethylamino) benzoyl) distamycin A (FCE 24517), doxorubicin (DX) and 3'-deamino-3' (2-methoxy-4-morpholinyl)-doxorubicin (FCE 23762). A significant correlation was demonstrated between the mean intracellular mBCl fluorescence values measured by flow cytometry and levels of GSH measured by the classical enzymatic assay, despite the possible influence of glutathione-S-transferases and of other thiols on the mBCl fluorescence. Although less specific, the flow cytometric method is more informative than the enzymatic assay, allowing detection of fluorescence distributions, which we proved to be characteristic of each subline.