Engineering 3-alkyltriazenes to block bcr-abl kinase: a novel strategy for the therapy of advanced bcr-abl expressing leukemias

Molecular Analysis of the Superior Efficacy of a Dual Epidermal Growth Factor Receptor (EGFR)-DNA-Targeting Combi-Molecule in Comparison with Its Putative Prodrugs 6-Mono-Alkylamino- and 6,6-Dialkylaminoquinazoline in a Human Osteosarcoma Xenograft Model

Background: ZR2002 is a dual EGFR-DNA-targeting combi-molecule that carries a chloroethyl group at the six-position of the quinazoline ring designed to alkylate DNA. Despite its good pharmacokinetics, ZR2002 is metabolized in vivo into dechlorinated metabolites, losing the DNA-alkylating function required to damage DNA. To increase the DNA damage activity in tumor cells in vivo, we compared ZR2002 with two of its 6-N,N-disubstituted analogs: "JS61", with a nitrogen mustard function at the six-position of the quinazoline ring, and "JS84", with an N-methyl group. Methods: Tumor xenografts were performed with the human Saos-2 osteosarcoma cell line expressing EGFR. Mice were treated with ZR2002, JS84 or JS61, and the tumor burden was measured with a caliper and CT/PET imaging. Drug metabolism was analyzed with LC-MS. EGFR and ɣ-H2AX phosphorylation were quantified via Western blot analysis and immunohistochemistry. Results: In vivo analysis showed that significant tumor growth inhibition was only achieved when ZR2002 was administered in its naked form. The metabolic dealkylation of JS61 and JS84 did not release sufficient concentrations of ZR2002 for the intratumoral inhibition of P-EGFR or enhanced levels of P-H2AX. Conclusions: The results in toto suggest that intratumoral concentrations of intact ZR2002 are correlated with the highest inhibition of P-EGFR and induction of DNA damage in vivo. ZR2002 may well represent a good drug candidate for the treatment of EGFR-expressing osteosarcoma.

Assessment of the biological potential of diaryltriazene-derived triazene compounds

In the present study, novel, 1,3-diaryltriazene-derived triazene compounds were synthesized and tested. Triazenes are versatile and belong to a group of alkylating agents with interesting physicochemical properties and proven biological activities. This study describes the synthesis, molecular and crystalline structure, biological activity evaluation, and antifungal and antimicrobial potentials of 1,3-bis(X-methoxy-Y-nitrophenyl)triazenes [X = 2 and 5; Y = 4 and 5]. The antimicrobial and antifungal activities of the compounds were tested by evaluating the sensitivity of bacteria (American Type Culture Collection, ATCC) and clinical isolates to their solutions using standardized microbiological assays, cytotoxicity evaluation, and ecotoxicity tests. The antimicrobial potentials of triazenes were determined according to their minimum inhibitory concentrations (MICs); these compounds were active against gram-positive and gram-negative bacteria, with low MIC values. The most surprising result was obtained for T3 having the effective MIC of 9.937 µg/mL and antifungal activity against Candida albicans ATCC 90028, C. parapsilosis ATCC 22019, and C. tropicallis IC. To the best of our knowledge, this study is the first to report promising activities of triazene compounds against yeast and filamentous fungi. The results showed the potential utility of triazenes as agents affecting selected resistant bacterial and fungal strains.

Anticancer Triazenes: from Bioprecursors to Hybrid Molecules

Triazenes are a very useful and diverse class of compounds that have been studied for their potential in the treatment of many tumors including brain tumor, leukemia and melanoma. Novel compounds of this class continue to be developed as either anticancer compounds or even with other therapeutic applications. This review focused on several types of triazenes from the simplest ones like 1,3-dialkyl-3-acyltriazenes to the more complex ones like combi-triazenes with an emphasis on how triazenes have been developed as effective antitumor agents.

The potential of combi-molecules with DNA-damaging function as anticancer agents

DNA-damaging agents, such as methylating agents, chloroethylating agents and platinum-based agents, have been extensively used as anticancer drugs. However, the side effects, high toxicity, lack of selectivity and resistance severely limit their clinical applications. In recent years, a strategy combining a DNA-damaging agent with a bioactive molecule (e.g., enzyme inhibitors) or carrier (e.g., steroid hormone and DNA intercalators) to produce a new 'combi-molecule' with improved efficacy or selectivity has been attempted to overcome these drawbacks. The combi-molecule simultaneously acts on two targets and is expected to possess better potency than the parent compounds. Many studies have shown DNA-damaging combi-molecules exhibiting excellent anticancer activity in vitro and in vivo. This review focuses on the development of combi-molecules, which possess increased DNA-damaging potency, anticancer efficacy and tumor selectivity and reduced side reactions than the parent compounds. The future opportunities and challenges in the discovery of combi-molecules were also discussed.

Combi-targeting concept: an optimized single-molecule dual-targeting model for the treatment of chronic myelogenous leukemia

Blockade of Bcr-Abl by the inhibitor Imatinib has proven efficacious in the therapy of chronic myelogenous leukemia (CML). However resistance to the drug emerges at the advanced phases of the disease. Therefore, novel therapy models remained to be designed. We have developed a novel dual targeted agent termed "combi-molecule" designed to not only block Bcr-Abl but also damage DNA. ZRF1, the first optimized prototype of the approach, was "programmed" to degrade into another inhibitor ZRF0 plus a methyl diazonium species. It was approximately 2-fold stronger Abl tyrosine kinase inhibitor than Imatinib and a more potent DNA-damaging agent than Temodal. In the p53 wild-type Mo7p210 cells, the potency of ZRF1 was approximately 1,000-fold superior to that of the equieffective combinations of Imatinib plus Temodal. More importantly, its superior potency over Imatinib was more pronounced in Bcr-Abl-positive cells coexpressing wild-type p53. Studies to rationalize these results showed that, through its Bcr-Abl inhibitory function, it down-regulated p53. However, sufficient level of the latter protein was available for transactivating p21 and Bax, which are required for cell cycle arrest and apoptosis. The results suggest that, in p53 wild-type cells, apoptosis is induced not only through Bcr-Abl inhibition but also through the p53-controlled DNA-damaging pathway, leading to an additive effect that translates into enhanced cell death. The study conclusively showed that p53 is a major determinant for the cytotoxic advantages of the novel combi-molecular approach in CML, a disease in which 70% to 85% of all the cases express wild-type p53.

STI571 reduces NER activity in BCR/ABL-expressing cells

Nucleotide-excision repair (NER) is the most versatile mechanism of DNA repair, recognizing and dealing with a variety of helix-distorting lesions, such as the UV-induced photoproducts cyclobutane pyrimidine dimers (CPDs) and pyrimidine (6-4) photoproducts. We investigated the influence of an anticancer drug, STI571, on the efficacy of NER in removing UV-induced DNA damage. STI571 is used mostly in the treatment of chronic myeloid leukemia and inhibits activity of the BCR/ABL oncogenic tyrosine kinase, which is a hallmark of this disease. NER activity was examined in the BCR/ABL-expressing cell lines K562 and BV173 of myeloid and lymphoid origin, respectively, as well as in CCRF-CEM cells, which do not express BCR/ABL. A murine myeloid parental 32D cell line and its counterpart transfected with the BCR/ABL gene were also tested. NER activity was assessed in the cell extracts by use of an UV-irradiated plasmid as a substrate and by a modified single-cell gel electrophoresis (comet) assay on UV-treated nucleoids. Additionally, quantitative PCR was performed to evaluate the efficacy of the removal of UV-induced lesions from the p53 gene by intact cells. Results obtained from these experiments indicate that STI571 decreases the efficacy of NER in leukemic cells expressing BCR/ABL. Therefore, STI571 may overcome the drug resistance associated with increased DNA repair in BCR/ABL-positive leukemias.

Optimization of novel combi-molecules: Identification of balanced and mixed bcr-abl/DNA targeting properties

Steps toward the identification of combi-molecules with strong abl tyrosine kinase (TK) inhibitory property and significant DNA damaging potential are described. The optimized combi-molecule 13a was shown to induce approximately twofold stronger abl TK inhibitory activity than Gleevec and high levels of DNA damage in chronic myelogenous leukemic cells.