Estrone-Decorated Polyion Complex Micelles for Targeted Melittin Delivery to Hormone-Responsive Breast Cancer Cells

Abstract

Tumor targeting has revolutionized cancer research, especially active cellular targeting of nanoparticles, where they are specifically homed to the pathological site to deliver the therapeutics. This strategy, which involves the utilization of affinity ligands on the surface of the nanocarriers, minimizes the nonspecific uptake of nanocarriers and the subsequent harmful side effects in healthy cells. Estrone, one of the mammalian estrogens, has affinity for estrogen receptors (ERα), which are overexpressed in hormone-responsive breast cancers. Despite holding promise, the potential of estrone in active targeting of nanoparticles has barely been explored. Herein, we developed an estrone-appended polyion complex (PIC) micelle to deliver melittin, a cytotoxic peptide, to breast cancer cells. Amino functionalization of estrone was performed to conjugate estrone to the diblock polymer synthesized by reversible addition–fragmentation chain-transfer (RAFT) polymerization. Estrone-conjugated poly­(ethylene glycol) methyl ether methacrylate-b-poly tert-butyl methacrylate (POEGMEMA-P t BuMA) could complex with melittin to form PIC micelles of size around 60 nm ensuing from the electrostatic interaction of the deprotected polymer and melittin in aqueous media. Poly­(ethylene glycol) methyl ether acrylate-b-poly acrylic acid (POEGMEA-PAA) was also later incorporated to afford PIC micelles that could exhibit similar cytotoxicity to free melittin in the cytotoxicity studies. The estrone-attached PIC micelles exhibited improved cytotoxicity in two-dimensional (2D) and three-dimensional (3D) cellular models of MCF-7 cells. Cross-linking of the PIC micelles was also performed to improve the stability of the micelles and prevent melittin degradation from enzymatic attack. Flow cytometry demonstrated an enhanced cellular uptake greater than sixfold with the estrone-conjugated PIC micelles, thereby establishing a profound difference in the targeting efficacy of the PIC micelles between MCF-7 and MDA-MB-231 cells. Furthermore, the distribution of the PIC micelles in the spheroids was revealed by light sheet microscopy. The results demonstrate the potential of estrone-anchored PIC micelles for targeted delivery of therapeutics to hormone-responsive breast cancer cells.

Enhancing Cationic Drug Delivery with Polymeric Carriers: The Coulomb‐pH Switch Approach

“…Cationic drugs such as peptides or proteins are typically delivered using negatively charged polymers such as poly(acrylic acid). [ 26 ] At low pH values, these polymers are partly protonated assisting with the release of the drug. Depending on the design of the negatively charged polymer, protonation is incomplete and the electrostatic interaction with the cationic drug is only weakened, but not eliminated.…”

Bioactive constituents of animal-derived traditional Chinese medicinal materials for breast cancer: opportunities and challenges

“…This drug vehicle system significantly enhanced the cytotoxicity on breast cancer cells compared to native bufalin, with no or few apparent side effects. In a further example, melittin delivered by citric acidfunctionalized Fe 3 O 4 magnetic nanoparticles (Hematyar et al, 2018), carbon nanoparticles (Daniluk et al, 2019) and perfluorocarbon nanoparticles (Soman et al, 2009), or an estrone-appended polyion complex micelle exhibited substantially greater antitumor efficacy against several breast cancer cells (Raveendran et al, 2020). Furthermore, an NCTD-loaded RGD (Arg-Gly-Asp)-decorated lipid-polymer hybrid nanoparticle inhibited TNBC tumor growth and metastasis via attenuating the Wnt/β-catenin pathway more effectively than free NCTD (Li YF et al, 2019).…”

Estrone-Conjugated PEGylated Liposome Co-Loaded Paclitaxel and Carboplatin Improve Anti-Tumor Efficacy in Ovarian Cancer and Reduce Acute Toxicity of Chemo-Drugs

“… 50 , 51 As a kind of estrogen, estrone (ES) can specifically bind to the ER and has a high affinity to the ER. 52 The presence of ER on the tumor cell membrane could be utilized for the treatment of ovarian cancer cells as a potential target for nanoparticle delivery of drugs. Therefore, using ES as a targeting ligand molecule in the liposomal delivery system could have the ability to deliver more chemotherapy drugs to the ovarian cancer tissues.…”