Overcoming multidrug resistance using folate receptor-targeted and pH-responsive polymeric nanogels containing covalently entrapped doxorubicin

Abstract

Multidrug resistance (MDR) contributes to failure of chemotherapy. We here show that biodegradable polymeric nanogels are able to overcome MDR via folic acid targeting. The nanogels are based on hydroxyethyl methacrylamide-oligoglycolates-derivatized poly(hydroxyethyl methacrylamide-co-N-(2-azidoethyl)methacrylamide) (p(HEMAm-co-AzEMAm)-Gly-HEMAm), covalently loaded with the chemotherapeutic drug doxorubicin (DOX) and subsequently decorated with a folic acid-PEG conjugate via copper-free click chemistry. pH-Responsive drug release is achieved via the acid-labile hydrazone bond between DOX and the methacrylamide polymeric network. Cellular uptake and cytotoxicity analyses in folate receptor-positive B16F10 melanoma versus folate receptor-negative A549 lung carcinoma cells confirmed specific uptake of the targeted nanogels. Confocal microscopy demonstrated efficient internalization, lysosomal trafficking, drug release and nuclear localization of DOX. We also show that DOX resistance in 4T1 breast cancer cells results in upregulation of the folate receptor, and that folic acid targeted nanogels can be employed to bypass drug efflux pumps, resulting in highly efficient killing of resistant cancer cells. In conclusion, folic acid functionalized nanogels with pH-controlled drug release seem to hold significant potential for treating multidrug resistant malignancies.

In Vitro Evaluation of Anti‐Aggregation and Degradation Behavior of PEGylated Polymeric Nanogels under In Vivo Like Conditions

“…The characteristics of the obtained copolymers are summarized in Table 1 . All copolymers were obtained with good yields (>80%) as reported previously . The number average molecular weight ranged from 10 to 15 kDa, which is smaller than kidney elimination threshold (45 kDa), with a PDI around 3.…”

“…The polymers were synthesized in two steps. First, p(HEMAm‐co‐AzEMAm) with different AzEMAm (5–20 mol%) was synthesized by free radical polymerization using HEMAm and AzEMAm as monomers and ABCPA as initiator (Figure S1A, Supporting Information) . The 1 H‐NMR spectra of p(HEMAm‐co‐AzEMAm) displayed a resonance peak of AzEMAm group at 3.46 ppm (Figure S1B, Supporting Information).…”

“…N ‐(2‐hydroxyethyl)methacrylamide (HEMAm), HEMAm‐oligoglycolates (HEMAm‐Gly, degree of polymerization 1.83), and N ‐(2‐azidoethyl)methacrylamide (AzEMAm) were synthesized as previously described . BCN‐PEG 5000 ‐OMe was purchased from SynAffix BV (Oss, the Netherlands).…”

“…Labeling of PEGylated and non‐PEGylated nanogels with Alexa 488 was performed according to a previously reported procedure . Freeze dried nanogels (10 mg) were dispersed in 1 mL of ammonium buffer (100 × 10 −3 m , pH 5) and 10 µL of Alexa 488 DIBO (1 mg mL −1 in DMSO) was added.…”

π-π-Stacked Poly(ε-caprolactone)-b-poly(ethylene glycol) Micelles Loaded with a Photosensitizer for Photodynamic Therapy

“…A similar trend (i.e., increasing photocytotoxicity with decreasing polymer molecular weight) was observed before and attributed to faster intracellular degradation of smaller PCL-PEG block copolymers, and thus faster release of mTHPC after internalization by the cells [24]. It is worth noting that the observed EC 50 values of these micellar mTHPC formulations on A431 and HeLa cells were slightly higher than free mTHPC (~1.5 µg/mL, Table 2), probably related to the less efficient cellular internalization of PEGylated micelles [53][54][55] or the relatively time-consuming degradation of polymers for release and activation of the PS [24]. Table 2.…”