Activation of clinically used anthracyclines by the formaldehyde-releasing prodrug pivaloyloxymethyl butyrate

Abstract

The anthracycline group of compounds is extensively used in current cancer chemotherapy regimens and is classified as topoisomerase II inhibitor. However, previous work has shown that doxorubicin can be activated to form DNA adducts in the presence of formaldehyde-releasing prodrugs and that this leads to apoptosis independently of topoisomerase II -mediated damage. To determine which anthracyclines would be useful in combination with formaldehyde-releasing prodrugs, a series of clinically relevant anthracyclines (doxorubicin, daunorubicin, idarubicin, and epirubicin) were examined for their capacity to form DNA adducts in MCF7 and MCF7/Dx (P-glycoprotein overexpressing) cells in the presence of the formaldehydereleasing drug pivaloyloxymethyl butyrate (AN-9). All anthracyclines, with the exception of epirubicin, efficiently yielded adducts in both sensitive and resistant cell lines, and levels of adducts were similar in mitochondrial and nuclear genomes. Idarubicin was the most active compound in both sensitive and resistant cell lines, whereas adducts formed by doxorubicin and daunorubicin were consistently lower in the resistant compared with sensitive cells. The adducts formed by doxorubicin, daunorubicin, and idarubicin showed the same DNA sequence specificity in sensitive and resistant cells as assessed by L-exonuclease -based sequencing of A-satellite DNA extracted from drug-treated cells. Growth inhibition assays were used to show that doxorubicin, daunorubicin, and idarubicin were all synergistic in combination with AN-9, whereas the combination of epirubicin with AN-9 was additive. Although apoptosis assays indicated a greater than additive effect for epirubicin/AN-9 combinations, this effect was much more pronounced for doxorubicin/AN-9 combinations.

Formaldehyde-Activated Pixantrone Is a Monofunctional DNA Alkylator That Binds Selectively to CpG and CpA Doublets

“…Much evidence has recently accumulated to suggest that the generation of a covalent linkage with DNA is an important and pertinent cytotoxic event of the anthracyclines (Skladanowski and Konopa, 1994a,b;Cutts et al, 2001Cutts et al, , 2007Swift et al, 2006). Mitoxantrone can also induce adducts in cancer cells; however, drug doses far in excess of growth inhibitory concentrations were required to generate these lesions, suggesting that this mechanism of action is biologically irrelevant (Parker et al, 2004).…”

Conformational diversity of anthracycline anticancer antibiotics: A density functional theory calculation

“…EPI, the axial hydroxyl at C4 0 of the daunosamine of DOX being epimerized to an equatorial hydroxyl, is less cardiotoxic than the original DOX [24]. The lesser cardiotoxicity and lesser anticancer activity of EPI are supposed to be direct results of the fact that the equatorial hydroxyl does not allow for stabilization by the mono-oxazolidine formation with free formaldehyde [26]. DNR, the hydroxyacetyl at C9 of DOX is substituted by an acetyl, is more effective in treatment of acute lymphoblastic or myeloblastic leukemias, while DOX is more effective in treatment of solid tumors and has wider spectrum of effectiveness than DNR [27,28].…”

Analysis of covalent ellipticine- and doxorubicin-derived adducts in DNA of neuroblastoma cells by the ³²P-postlabeling technique

“…3F). Because the nuclease P1 version of the 32 P-postlabeling method might have limitations for detecting some of DNA adducts 35 , we also used other versions of the 32 P-postlabeling method such as the standard procedure 28 , this procedure under the ATP-deficient conditions 30 and the version utilizing of extraction of adducts into nbutanol 35 to analyze doxorubicin-derived DNA adducts (Fig. 3D-G).…”

“…Using 14 C-labeled doxorubicin, doxorubicin-DNA adduct formation has been detected in several cancer cells 17,20,21,25 . Moreover, accelerator mass spectrometry has recently also been shown suitable for detecting the covalent 14 C-labeled doxorubicin-DNA adducts in cancer cells exposed to this drug [26][27][28] . Utilizing the 14 C-labeled doxorubicin has, however, limitations for use in human treatment.…”