A novel doxorubicin-mitomycin C co-encapsulated nanoparticle formulation exhibits anti-cancer synergy in multidrug resistant human breast cancer cells

Abstract

Anthracycline-containing treatment regimens are currently the most widely employed regimens for the management of breast cancer. These drug combinations are often designed based on non-cross resistance and minimal overlapping toxicity rather than drug synergism. Moreover, aggressive doses are normally used in chemotherapy to achieve a greater therapeutic benefit at the cost of more acute and long-term toxic effects. To increase chemotherapeutic efficacy while decreasing toxic effects, rational design of drug synergy-based regimens is needed. Our previous work showed a synergistic effect of doxorubicin (DOX) and mitomycin C (MMC) on murine breast cancer cells in vitro and improved efficacy and reduced systemic toxicity of DOX-loaded solid polymer-lipid hybrid nanoparticles (PLN) in animal models of breast cancer. Herein we have demonstrated true anticancer synergy of concurrently applied DOX and MMC, and have rationally designed PLN to effectively deliver this combination to multidrug resistant (MDR) MDA435/LCC6 human breast cancer cells. DOX-MMC co-loaded PLN were effective in killing MDR cells at 20-30-fold lower doses than the free drugs. This synergistic cell killing was correlated with enhanced induction of DNA double strand breaks that preceded apoptosis. Importantly, co-encapsulation of dual agents into a nanoparticle formulation was much more effective than concurrent application of single agent-containing PLN, demonstrating the requirement of simultaneous uptake of both drugs by the same cells to enhance the drug synergy. The rationally designed combination chemotherapeutic PLN can overcome multidrug resistance at a significantly lower dose than free drugs, exhibiting the potential to enhance chemotherapy and reduce the therapeutic limitations imposed by systemic toxicity.

A calorimetric investigation of doxorubicin–polymer bead interactions

“…To overcome this 30 problem several delivery strategies have been developed such as solid lipid nanoparticles and nanoliposomal 31 delivery systems, for example Doxil ® (Natarajan et al, 2014). Ion-exchange microspheres and, in particular, drug-eluting beads, have become the system of choice for drug delivery (Liu et al, 2001;Shuhendler et al, 2010). For 33 over a decade transarterial chemoembolisation using drug eluting beads (DEBs) has been a treatment option for 34 primary and secondary liver cancers.…”

Strategies for optimizing polymer-lipid hybrid nanoparticle-mediated drug delivery

“…[1,3] Since then, various PLN formulations have been developed to encapsulate a single anticancer drug, [4] or co-encapsulate a drug with a chemosensitizer, [1,3] a drug with a P-glycoprotein (P-gp) inhibitor, [5] or dual anticancer drugs of synergy. [6] PLN formulations have also been developed to deliver biologics for gene therapy and immunotherapy, including siRNA [7] or siRNA with an anticancer drug. [8] PLN formulations have been shown to circumvent efflux transporter-mediated multidrug resistance (MDR) in cancer cells [1,4,6,9] and increase antitumor efficacy while reducing systemic toxicity of the anticancer drugs.…”

“…[6] PLN formulations have also been developed to deliver biologics for gene therapy and immunotherapy, including siRNA [7] or siRNA with an anticancer drug. [8] PLN formulations have been shown to circumvent efflux transporter-mediated multidrug resistance (MDR) in cancer cells [1,4,6,9] and increase antitumor efficacy while reducing systemic toxicity of the anticancer drugs. [10,11] It was found that the PLN facilitated drug uptake and retention in P-gp overexpressing cancer cells, provided effective intracellular drug release, transported the drug (e.g.…”

“…doxorubicin) to the nuclei where drug target (i.e. DNA) is located, [4,6,10] and enabled spatiotemporal co-delivery and local bioavailability of anticancer drugs in solid tumor and cancer cells. [12] Owing to these unique properties and more desired drug release kinetics than clinically used liposomal doxorubicin (Doxil®/Caelyx®) which has a long release half-life of 118 hours, a PLN formulation with co-encapsulated synergistic anticancer drugs, that is, doxorubicin and mitomycine C, outperformed Doxil®/Caelyx® in MDR cancer cells and in preclinical tumor models.…”

“…endogenous fatty acids). Up to date, reported PLN formulations can be divided into two major categories as schematically illustrated in Figure 1: type A -monolithic matrix PLN, where polymer and drug(s) are homogeneously distributed in the solid lipid matrix, [1,[3][4][5][6][9][10][11][12] and type Bcore-shell PLN, where drug-containing polymer core is covered by a single layer of phospholipid. [7,8,13] The latter is sometimes called lipid-polymer hybrid nanoparticles (LPN) in literature.…”