Peptide-Doxorubicin Conjugates for Mitigating Cardiotoxicity and Overcoming Drug Resistance in Cancer - PROJECT SUMMARY Doxorubicin (DOX) is an FDA-approved anthracycline chemotherapy drug that is utilized for the treatment of a range of cancers, such as breast, lung, ovarian, gastric, and thyroid. However, the clinical application of DOX has demonstrated multidrug resistance and unfavorable pharmacokinetic qualities, such as low bioavailability, rapid distribution, and excretion. Thus, a higher dose of DOX is required for chemotherapy. However, it is well documented that higher cumulative doses of DOX lead to dose-dependent cardiotoxicity, nephrotoxicity, and extravasation. Despite extensive research on targeted therapy systems, the safe, effective, and exclusive delivery of DOX to target cells remains elusive. The long-term objective of this proposal is to harness the potential of cyclic- and hybrid cyclic-linear peptide-DOX conjugates to address DOX cardiotoxicity and combat drug resistance in cancer cells. Our preliminary data demonstrate the efficacy and low toxicity of peptide-DOX conjugates (PDCs) against Dox-resistant and cardiac cells, respectively. We hypothesize that optimized PDCs can effectively target and overcome DOX-resistant cancer cells while reducing cardiotoxicity, thus enhancing therapeutic efficacy. We will pursue two Specific Aims to test this hypothesis. In Aim 1, we will investigate the differential mechanism of cardiotoxicity mitigation and overcoming DOX-resistant cancer cells by five PDCs, [W(RW)4K]βA-DOX, [R5K]W7-βA-DOX, [W(RW)8K]βA-DOX, [(WR)4C]-S-S-DOX, and [R5W4]K- RRWWRLWRRLWRβA-DOX. Three primary mechanisms underpinning the cardiotoxic effects of DOX include (i) generation of reactive oxygen species (ROS) leading to membrane damage, (ii) apoptosis in cardiomyocytes, and (iii) modulation of intracellular calcium release. We will elucidate the mechanisms that differentiate their cytotoxic effects on cancer cells versus cardiomyocytes. We will also evaluate the mechanism of activity of PDCs using DOX-resistant cells that have overexpression of membrane efflux proteins. We will monitor the internalization and intracellular trafficking of the PDCs and released DOX, and their interactions with membrane efflux protein (e.g., P-gp) in the heart, DOX-resistant, and cancer cells. Aim 2 is focused on the in vivo evaluation of three functionalized PDCs for DOX delivery to cancer xenograft models and the evaluation of cardiotoxicity. These studies will involve inducing tumors in immunodeficient mice using both naïve and resistant cells. We will evaluate the distribution, tumor-suppressive efficacy, cardiotoxicity, and safety profile of three functionalized PDCs with PEG and folic acid or RGD. The outcomes of this project will contribute to our understanding of how peptide structure affects both cardiotoxicity and the mitigation of DOX resistance and could greatly improve the effectiveness and safety of DOX for cancer treatment. This project closely aligns with the missions of the National Heart, Lung, and Blood Institute (NHLBI) and National Cancer Institute (NCI), as well as the NIH REAP (R15) FOA. It enables undergraduate and graduate students to participate in valuable research, enriches our institution's research milieu, and advances translational research in cardiovascular and cancer fields.
