Anthracyclines are common chemotherapeutic agents used in many cancers which are refractory to other therapeutic alternatives. In triple negative breast cancer which is commonly observed in African-American women (AA) and tend to be more aggressive, carry worse prognoses and are harder to manage because they lack the molecular targets required for therapies, anthracyclines are some of the few therapeutic alternatives. Although effective, resistance to this agent usually arises and serious side-effects like the development of cardiomyopathy limits their use. To increase our knowledge of the pathways that protect cells from anthracyclines we carried out a genome-wide genetic screening in the eukaryotic model organism S. cerevisiae to identify gene defects that generate cells hypersensitive to doxorubicin. A total of 71 deletion strains displayed varying levels of sensitivity to anthracyclines. Among these, mutants of HOM6 confer significant increased sensitivity to doxorubicin. This effect appears to be due to the accumulation of the threonine intermediate L-aspartate-semialdehyde and can be abolished by the inactivation of a prior step, involving HOM3, which prevents the accumulation of the intermediate. In order to further characterize the synergism of aldehydes and doxorubicin, we have tested the effect of different aldehydes on the cytotoxicity of cells exposed to anthracyclines.
Our data show that treatment with formaldehyde (2 mM) reduced the survival of the wild type strain to 78%. However, in the presence of doxorubicin, formaldehyde reduced the viability of the strain by between 31 to 39-fold (with 10 µM doxorubicin) relative to doxorubicin and formaldehyde alone and by ∼110-fold relative to doxorubicin at 150 µM concentration.
Co-treatment with formaldehyde and doxorubicin of anthracycline-resistant strains siz1 and msh2 also shows increased toxicity. However, the synergistic effect is not as pronounced in these strains compared to the wild type. Among the aldehydes tested, formaldehyde was most effective. Glutaraldehyde and acetaldehyde displayed distinct effect on strains siz1, and ald5. The potential use of a combination of aldehydes and cytotoxic drugs could potentially lead to applications intended to enhance anthracycline-based therapy. This possibility will be discussed, as well as the targeting of aldehydes in relevant human pathways.
Research supported by NIH/NCRR RCMI grant #RR03020 at Florida A&M University.
Citation Format: Jana Sharrae Miles, Tryphon Mazu, Selina Darling-Reed, Hernan Flores-Rozas. Distinct effect of aldehydes in anthracycline cytotoxicity in S. cerevisiae. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 1785. doi:10.1158/1538-7445.AM2014-1785