Inhibitory Effect of Paclitaxel and Rapamycin Individual and Dual Drug-Loaded Polymeric Micelles in the Angiogenic Cascade

Abstract

Angiogenesis is an essential process for disease progression in many solid tumors. There are several major cascade events in the angiogenic process that can be targeted to inhibit new blood vessel formation in the tumor tissue. The purpose of this work is to evaluate the inhibitory effect of paclitaxel (PTX) and rapamycin (RAP) as individual and in dual drug-loaded poly(ethylene glycol)-block-poly(d,l-lactic acid) (PEG-b-PLA) micelles on the angiogenic cascade processes of proliferation, migration, and tube formation. PEG-b-PLA PTX and/or RAP micelles were formed and characterized for size and drug loading. Sizes of individual and dual drug micelles were below 40 nm. PEG-b-PLA micelles significantly enhanced the aqueous solubility of PTX 1.80 mg/mL and RAP 1.60 mg/mL. The PTX-RAP dual drug PEG-b-PLA micelles were able to load PTX and RAP at 1.60 mg/mL for both drugs. Cell proliferation, apoptosis, tubule formation, and migration studies were performed in human umbilical vein endothelial cells (HUVEC). PTX and RAP in DMSO inhibited HUVEC proliferation with IC50 values of 0.82 ± 0.02 and 13 829 ± 681 nM, respectively, while the combination of both drugs in DMSO produced synergistic inhibition. PTX and RAP individual micelles had IC50 values of 6.3 ± 1.1 and 14 051 ± 821 nM, respectively. PTX and dual drug micelles had a synergistic inhibition effect on HUVEC proliferation through the induction of apoptosis via caspase 3/7 activity. In vitro tube formation assay demonstrated significant inhibition of tube formation upon treatment with dual drug micelles as compared to individual PTX or RAP micelles. Migration studies in HUVEC have shown that individual PTX micelles inhibited cell migration at 1 nM, while RAP micelles did not show any inhibitory effect on cell migration. Interestingly, the presence of RAP in the dual drug micelles was able to initiate the inhibition of the migration of HUVEC at 0.1 nM concentration of PTX. These results indicate that PTX-RAP dual drug micelles have antiangiogenic effects in vitro mediated through three major events in the angiogenic process and have strong potential for further development as antiangiogenic chemotherapy.

Nanoformulations for combination or cascade anticancer therapy

“…The amphiphilic copolymers have also demonstrated better loading capacity for the encapsulated drugs. Mishra et al have encapsulated PTX and rapamycin (RAPA) into PEG-b-PLA for synergistic antitumor therapy [103]. To increase the cellular uptake efficiency, chitosan was also used as a material for surface functionalization of NPs.…”

Combinatorial Polymeric Conjugated Micelles with Dual Cytotoxic and Antiangiogenic Effects for the Treatment of Ovarian Cancer

“…Thus, in the case of MIX-M the tumor volume reduction is also driven by the inhibition of the angiogenesis, while in the case of the individual micelles, at these concentrations only angiogenesis inhibition occurs but no cytotoxic effects are seen. The ability of PTX and RAP to induce an antiangiogenic effect is well documented in the literature and many studies have shown that the endothelial cells and neovasculature are sensitive to these agents at concentrations lower than that required for cancer cells 18,22,33 . Clearly the PTX-M and RAP-M follow the same pattern at 20 mg/kg to produce antiangiogenic effects without apoptosis induction in the tumor tissue.…”

“…The treatment groups in both experiments were HUVEC left untreated (control), treated with 0.2 nM of PTX, RAP in individual micelles or 0.1 nM of each in MIX-M. PTX-M and RAP-M concentrations selected for the studies were below the IC 50 values in HUVEC of the micelles (Fig.5). This selection was based on earlier findings that PTX and RAP inhibit endothelial migration and tube formation at much lower doses than their IC 50 33,70 . Data from the migration assay is presented in Fig.…”

“…This assumption is based on previous findings in which RAP has the ability to potentiate the effect of PTX and docetaxel through inhibition of cancer cell proliferation and induction of apoptosis 67,69 . In addition, Mishra et al showed that RAP produces antiangiogenic effects and acts synergistically with PTX to inhibit the angiogenic cascade processes of proliferation, migration, and tube formation 33 . These finding are further confirmed in our work in which we have shown that MIX-M affects angiogenesis by inhibiting HUVEC cells proliferation, migration, and tube formation (Figs.…”

Combination of light-driven co-delivery of chemodrugs and plasmonic-induced heat for cancer therapeutics using hybrid protein nanocapsules

“…Unfortunately, antineoplasic drugs used in conjunction within a single formulation/delivery system are not commercially available so far [10]. The combination of two or more different drugs within one single nanocarrier might help in simplifying tumor treatments, make them much less harmful to patients by allowing: (i) drugs transport to their site of action by passive and/or active mechanisms; (ii) drug protection and avoidance of early clearance from the body; (iii) their sustained and controlled release from the nanocarrier to achieve optimal therapeutic doses in situ; and (iv) the enhancement of their circulation times and the improvement of their pharmacokinetics and pharmacodynamics [11, 12].…”