Abstract
Purpose
Temozolomide (TMZ), an oral alkylating agent with good penetration of the blood-brain barrier, has shown efficacy in the treatment of malignant brain tumors. Ribonucleotide reductase (RR), the rate-limiting enzyme of DNA synthesis, seems to be a complementary target for combination chemotherapy of brain tumors. Trimidox (TX) and didox (DX) are two recently synthesized specific inhibitors of RR. The combinations of TMZ with TX or DX as a basis for synergistic chemotherapy protocols were tested in this study.
Methods
The effects of the single drugs TMZ, DX, and TX, and the combinations TMZ/DX and TMZ/TX were evaluated in the human malignant glioma cell lines U87MG, T98G, LNZ308, and wt1119. In the latter, experiments were carried out in the presence or absence of wild-type p53 protein expressed under the control of a tetracycline-responsive transgene system. Cytotoxicity was evaluated by MTT assays. The isobologram and combination index (CI) method of Chou-Talalay were used to evaluate interactions between drugs.
Results
All drugs demonstrated cytotoxicity in brain tumor cells. Synergistic cytotoxic effects (CI<1) for TMZ and TX or DX at different dose levels were demonstrated in most of the examined cell lines. In some instances, however, drug combinations resulted in additive or even antagonistic effects. Toxicity of the single agents and synergy of the combinations did not correlate with wild-type p53 expression in the tumor cells.
Conclusion
The tumor toxicity of TMZ as a single agent may be modified by combinations with the novel RR inhibitors DX and TX, and is synergistically enhanced in most cases. Depending on the combination ratio, the doses for each drug for a given degree of effect in the combination may be drastically reduced.
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References
Alvino E, Pepponi R, Pagani E, Lacal PM, Nunziata C, Bonmassar E, D'Atri S (1999) O(6)-benzylguanine enhances the in vitro immunotoxic activity of temozolomide on natural or antigen-dependent immunity. J Pharmacol Exp Ther 291:1292
Bower M, Newlands ES, Bleehen NM, Brada M, Begnet RJH, Calvert H, Colquhoun I, Lewis P, Brampton MH (1997) Multicentre CRC phase II trial of temozolomide in recurrent or progressive high-grade glioma. Cancer Chemother Pharmacol 40:484
Burger PC, Green SB (1987) Patient age, histologic features and length of survival in patients with glioblastoma multiforme. Cancer 59:1617
Chang TT, Chou TC (2000) Rational approach to the clinical protocol design for drug combinations: a review. Acta Paediatr Taiwan 41:294–302
Chou TC (1991) The median-effect principle and the combination index for quantitation of synergism and antagonism. In: Chou TC, Rideout DC (eds) Synergism and antagonism in chemotherapy. Academic Press, New York, pp 61–102
Chou TC (1998) Drug combinations: from laboratory to practice. J Lab Clin Med 131:6
Chou TC, Hayball M (1996) CalcuSyn for Windows, multiple drug dose-effect analyzer and manual. Biosoft, Cambridge, UK
Chou TC, Talalay P (1984) Quantitative analysis of dose-effect relationships: the combined effects of multiple drugs or enzyme inhibitors. Adv Enzyme Regul 22:27
Chou TC, Motzer RJ, Tong Y, Bosl GJ (1994) Computerized quantitation of synergism and antagonism of taxol, topotecan and cisplatin against human teratocarcinoma cell growth: a rational approach to clinical protocol design. J Natl Cancer Inst 86:1517
Clark AS, Deans B, Stevens MF, Tisdale MJ, Wheelhouse RT, Denny BJ, Hartley JA (1995) Antitumor imidazotetrazines. Synthesis of novel imidazotetrazinones and related bicyclic heterocycles to probe the mode of action of the antitumor drug temozolomide. J Med Chem 38:1493–1504
D'atri S, Tentori L, Lacal PM, Graziani G, Pagani E, Benincasa E, Zambruno G, Bonmassar E, Jiricny J (1998) Involvement of the mismatch repair system in temozolomide-induced apoptosis. Mol Pharmacol 54:334–341
Elford HL, Freese M, Passamani E, Morris HP (1970) Ribonucleotide reductase and cell proliferation. J Biol Chem 245:5228–5333
Fritzer-Szekeres M, Grusch M, Luxbacher C, Horvath S, Krupitza G, Elford HL, Szekeres T (2000) Trimidox, an inhibitor of ribonucleotide reductase, induces apoptosis and activates caspases in HL-60 promyelocytic leukemia cells. Exp Hematol 28:924–930
Fritzer-Szekeres M, Salamon A, Grusch M, Horvath Z, Hochtl T, Steinbrugger R, Jager W, Krupitza G, Elford HL, Szekeres T (2002) Trimidox, an inhibitor of ribonucleotide reductase, synergistically enhances the inhibition of colony formation by Ara-C in HL-60 human promyelocytic leukemia cells. Biochem Pharmacol 64:481–485
Goan YG, Zhou B, Hu E, Mi S, Yen Y (1999) Overexpression of ribonucleotide reductase as a mechanism of resistance to 2,2-difluorodeoxycytidine in the human KB cancer cell line. Cancer Res 59:4204–4207
Hirose Y, Berger MS, Pieper RO (2001) Abrogation of the Chk1-mediated G2 checkpoint pathway potentiates temozolomide-induced toxicity in a p53-independent manner in human glioblastoma cells. Cancer Res 61:5843–5849
Kleihues P, Burger PC, Scheithauer BW (1993) Histological typing of tumors of the central nervous system, 2nd edn. Springer, Berlin
Liu L, Markowitz S, Gerson SL (1996) Mismatch repair mutations override alkyltransferase in conferring resistance to temozolomide but not to 1,3-bis(2-chloroethyl)-nitrosourea. Cancer Res 56:5375–5379
Macdonald DR (2001) Temozolomide for recurrent high-grade glioma. Semin Oncol 4 [Suppl 13]:3–12
Rauko P, Romanova D, Miadakova E, Macakova K, Novotny L, Elford HL, Szekeres T (1997) DNA-protective activity of new ribonucleotide reductase inhibitors. Anticancer Res 17:3437–3440
Romanova D, Vachalkova A, Szekeres T, Elford HL, Novotny L (1997) The new inhibitors of ribonucleotide reductase—comparison of some physico-chemical properties. J Pharm Biomed Anal 15:951–956
Shugg D, Allen BJ, Blizzard L, Dwyer T, Roder D (1994) Brain cancer incidence, mortality and case survival: observations from two Australian cancer registries. Int J Cancer 59:765–770
Szekeres T, Vielnascher E, Novotny L, Vachalkova A, Fritzer M, Findenig D, Göbl R, Elford HL, Goldenberg H (1995) Iron binding capacity of Trimidox (3,4,5-trihydroxy-benzamidoxime), a new inhibitor of the enzyme ribonucleotide reductase. Eur J Clin Chem Clin Biochem 33:785–789
Takeda E, Weber G (1981) Role of ribonucleotide reductase in the expression of the neoplastic program. Life Sci 28:1007–1014
Tentori L, Graziani G, Gilbert S, Lacal PM, Bonmassar E, D'atri S (1995) Triazene compounds induce apoptosis in O-(6)-alkylguanine-DNA alkyltransferase deficient leukemia cell lines. Leukemia 9:1888–1895
Van Meir EG, Polverini PJ, Chazin VR, Su Huang HJ, De Tribolet N, Cavenee WK (1994) Release of an inhibitor of angiogenesis upon induction of wild type p53 expression in glioblastoma cells. Nat Genet 8:171–176
Acknowledgements
This study was supported in part by the German Research Council (DFG) (grant Ra 705/4-1, to N.G.R.), the State Ministry of Culture and Education of Saxony-Anhalt (grants 2794A/0087H to N.G.R. and 3225A/0020G to A.S.), and the Roggenbuck Foundation Hannover, Germany (to N.G.R.).
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Figul, M., Söling, A., Dong, H.J. et al. Combined effects of temozolomide and the ribonucleotide reductase inhibitors didox and trimidox in malignant brain tumor cells. Cancer Chemother Pharmacol 52, 41–46 (2003). https://doi.org/10.1007/s00280-003-0611-2
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DOI: https://doi.org/10.1007/s00280-003-0611-2