Doxorubicin delivered by redox-responsive Hyaluronic Acid–Ibuprofen prodrug micelles for treatment of metastatic breast cancer

Highlights

• A HA-ibuprofen prodrug (HA-ss-BF) was prepared by incorporated ibuprofen (BF) into HA backbone through disulfide bonds.

• The HA-ss-BF prodrug could down-regulate COX-2 expression via on-demand BF release.

• The doxorubicin-loading HA-ss-BF prodrug micelles suppressed primary tumor growth and metastasis of breast cancer in vivo.

Abstract

During the process of cancer metastasis, various enzymes, cytokines, and factors were involved, and upregulated cyclooxygenase-2(COX-2) in tumor cells led to proliferation and invasion of various tumors. Many nonsteroidal anti-inflammatory drugs (NSAIDs) were used as an anticancer adjuvant in chemotherapy, such as ibuprofen (BF) and celecoxib. NSAIDs could effectively inhibit local inflammation and decreased COX-2 expression. However, most of them have serious toxicity issues due to their limit selectivity against cancer and poor water solubility. Thus hyaluronic acid-ibuprofen (HA-ss-BF), which was sensitive to the reducing environment, was prepared by binding ibuprofen (BF) to the hyaluronic acid backbone through a disulfide bond, and the HA-ss-BF polymer could self-assemble into micelles and serve as carriers to delivery doxorubicin. These redox-sensitive prodrug polymeric micelles hold multiple therapeutic advantages, including on-demand BF release and disassembling micelles responding to redox stimuli, as well as desirable cellular uptake and favorable biodistribution. These advantages indicated the redox-responsive hyaluronic acid-ibuprofen prodrug could be a promising delivery system for metastatic breast cancer treatment.

Introduction

In the complex process of cancer cell metastasis, various enzymes, pro-inflammatory cytokines and growth factors were involved (Kozłowski, Kozłowska, & Kocki, 2015; Su, Yang, Xu, Chen, & Yu, 2015). For example, overexpressing cyclooxygenase-2 in tumor cells induced proliferation and invasion of various tumors, leading to the inadequate survival rate of patients (Güler, Kaya, cSen, Nazli, & Güllüouglu, 2016; Sun, Zhang et al., 2017). Compared to cyclooxygenase-1 (COX-1), cyclooxygenase-2(COX-2) overexpressed in various tumors and catalyzed the secretion of excess prostaglandin E2, and excess prostaglandin E2 inhibited tumor cell apoptosis, activated angiogenesis, and promoted tumor cell invasiveness(Regulski et al., 2016; Yu, Lao, & Zheng, 2016). Thus, nonsteroidal anti-inflammatory drugs (NSAIDs) such as ibuprofen and naproxen were used as an anticancer adjuvant in chemotherapy, which not only reduced local inflammation but inhibited metastatic cancer associated with COX-2(Gulyas et al., 2018; Rescifina et al., 2019; Said-Elbahr, Nasr, Alhnan, Taha, & Sammour, 2016). However, most NSAIDs hold low solubility in water and led to gastrointestinal and cardiovascular side effects, which limited their farther use in anticancer treatments(Brune & Patrignani, 2015).

Since last decades, prodrug polymeric micelles (PMs) have been widely used as tumor-targeting nanoscale carriers, which can entrap anti-cancer drugs to improve their water solubility and bioavailability. Further, PMs can permeate selectively through more porous blood vasculature in solid tumors to enhance the intratumoral accumulation and thus the anti-cancer effects of the payload drugs(Biswas, Kumari, Lakhani, & Ghosh, 2016), moreover, the prodrug polymers could achieve co-delivery different drugs and achieve the synergistic effect(Ha, Zhao, Chen, Jiang, & Shi, 2018; Seetharaman, Kallar, Vijayan, Muthu, & Selvam, 2017; Sun, Liu et al., 2017). However, its lack of active tumor targeting and un-programmed release of drug at the desired site limited further use in clinical application (Sun, Liu et al., 2017; Yin et al., 2018; Zeng et al., 2017). For achieving controlled release, stimuli-responsive linkages between the drug and polymer backbone were incorporated into prodrug polymeric materials, such as enzymes, pH values, redox potentials, and oxidative stress triggered spatiotemporal payloads release(Wei, Gao, Li, & Serpe, 2017). For example, Zhang prepared pH-sensitive drug delivery carriers based on PEG-derivatized ibuprofen dually delivery anticancer agents and ibuprofen, which not only increased the solubility of ibuprofen and showed synergistic antitumor effect with doxorubicin(Zeng et al., 2017). However, different pathological sites may hold similar pH profiles and lack of active tumor targeting considerably restrict the further the use of pH sensitive-drug delivery system with ibuprofen(Abri Aghdam et al., 2019). Compared to un-specificity pH profile, it is reported that the glutathione (GSH) concentrations in the cytoplasm of tumor cell was about10^-4-10^-3 M, while in the extracellular compartment, the GSH concentrations were only 10^-6-10^-5 M(Ai et al., 2014). This spatial difference in GSH distribution triggered disulfide bonds preferentially cleaved in cancer cells, releasing the payload in the tumor cells(Jeong, Jeong, & Nah, 2019; B. Li et al., 2019; Luo et al., 2016; Q. Sun et al., 2018).

Hyaluronic acid (HA) is a well-known linear polysaccharide, consisting of β-1,4-D-glucuronic acid and β-1,3-N-acetyl-d-glucosamine. Due to characteristics of non-toxic, biodegradable, low-immunogenic, hyaluronic acid played important roles in improving tumor-targeting efficiency of nanoparticles(NPs), and more importantly, HA showed high affinity to CD44 receptors which were up-regulated in various cancer cells(Dosio, Arpicco, Stella, & Fattal, 2016). Thus HA was widely tailored to hydrophobic molecules or to nano-carriers(Wickens et al., 2017). For example, Wang prepared a novel liver-tumor-targeted self-assembled nanoparticle via conjugation glycyrrhetinic acid (GA) with the hydroxyl group of hyaluronic acid, which could target liver tumor cells in vitro and in vivo(Wang, Gu, Wang, Yang, & Mao, 2018).

Thus, in order to maximize the inhibition effect of metastatic breast cancer from ibuprofen with the minimized side effects, a hyaluronic acid-ibuprofen prodrug (HA-ss-BF) responsive to redox environments was synthesized by incorporated ibuprofen (BF) into HA backbone through disulfide bonds. And the HA-ss-BF polymer could self-assemble into micelles, and serving as carriers to payload Dox. We hypothesize that Dox-loaded HA-ss-BF micelles could be efficiently internalized by tumor cells via CD44 receptors, controlled release Dox and BF. We hopped that Dox-loaded HA-ss-BF micelles not only inhibit primary tumor growth of breast cancer but also hindered the metastasis of breast cancer via COX-2 path.