International Journal of Biological Sciences
Volume 9, Issue 4
Antineoplastic Agents--adverse effects; P-Glycoprotein--deficiency; Proto-Oncogene Proteins--deficiency
Background: Anthracyclines, such as doxorubicin (Adriamycin), are highly effective chemotherapeutic agents, but are well known to cause myocardial dysfunction and life-threatening congestive heart failure (CHF) in some patients.
Methods: To generate new hypotheses about its etiology, genome-wide transcript analysis was performed on whole blood RNA from women that received doxorubicin-based chemotherapy and either did, or did not develop CHF, as defined by ejection fractions (EF)≤40%. Women with non-ischemic cardiomyopathy unrelated to chemotherapy were compared to breast cancer patients prior to chemo with normal EF to identify heart failure-related transcripts in women not receiving chemotherapy. Byproducts of oxidative stress in plasma were measured in a subset of patients.
Results: The results indicate that patients treated with doxorubicin showed sustained elevations in oxidative byproducts in plasma. At the RNA level, women who exhibited low EFs after chemotherapy had 260 transcripts that differed >2-fold (pIn vitro studies confirmed that inhibition of MDR1 by verapamil in rat H9C2 cardiomyocytes increased their susceptibility to doxorubicin-induced toxicity.
Conclusions: It is proposed that chemo-induced cardiomyopathy may be due to a reduction in TCL1A levels, thereby causing increased apoptotic sensitivity, and leading to reduced cardiac MDR1 levels, causing higher cardiac levels of doxorubicin and intracellular free radicals. If so, screening for TCL1A and MDR1 SNPs or expression level in blood, might identify women at greatest risk of chemo-induced heart failure.
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McCaffrey, T.A., Tziros, C., Lewis, J., Katz, R., Siegel, R., Weglicki, W., Kramer, J., Mak, I.T., Toma, I., Chen, L., Benas, E., Lowitt, A., Rao, S., Witkin, L., Lian, Y., Lai, Y., Yang, Z., Fu, S.W. Genomic profiling reveals the potential role of TCL1A and MDR1 Deficiency in chemotherapy-induced cardiotoxicity. International Journal of Biological Sciences, 9(4), 350-360.