Sulforaphane delivery using mPEG–PCL co-polymer nanoparticles to breast cancer cells

Abstract

Purpose: Among the potent anticancer agents, d,l-sulforaphane (SF) is very effective against many different types of cancer cells. Its clinical application is restricted because of its hydrophobicity, low gastrointestinal absorption and poor bioavailability. In the present study, a reliable micellar delivery system using monomethoxypoly (ethylene glycol)–poly (ɛ-caprolactone) (mPEG–PCL) was established. The encapsulation of SF inside mPEG–PCL as a nano-carrier was established and the cytotoxicity assay against human breast cancer cell line was evaluated.

Methods: In this study, SF was encapsulated within mPEG–PCL micelles through a single-step nano-precipitation method, leading to creation of SF-loaded mPEG–PCL (SF/mPEG–PCL) micelles. Di-block mPEG–PCL copolymers were synthesized and used to prepare micelles. MPEG-PCL copolymer was characterized by HNMR, FTIR, differential scanning calorimetry and gel permeation chromatography techniques. Characterization, stability of micelles, the particle size and morphology were determined. The release profile of the SF from the micelles which prepared by the drug-loaded copolymer, was evaluated. The cytotoxicity of free SF, mPEG–PCL and SF-loaded mPEG–PCL micelles was compared with each other by performing MTT assay of the treated MCF-7 cell line. Expression levels of BCL-2, MMP-9, BCL-XL, BAK, BAX and GAPDH (endogenous gene) as control were quantified by real time PCR. To evaluate the apoptotic effects of Free SF compared with SF-loaded mPEG–PCL micelles, flow cytometry analysis was done using the annexin V-FITC apoptosis detection kit.

Results: Our studies resulted in a successful establishment of uniformity and spherical SF-loaded mPEG–PCL micelles. The encapsulation efficiency of SF was 86 ± 1.58%. The results of atomic force microscopy revealed that the micelles have spherical shapes with size of 107 nm. In vitro release of SF from SF-entrapped micelles was remarkably sustained. The mPEG–PCL micelle showed little cytotoxicity in the case of MCF-7 cell line with concentration up to 1.5 mg/ml, whereas the SF-loaded mPEG–PCL micelles at all concentrations significantly was cytotoxic in the case of MCF-7 cell line. Finally, real-time PCR and flow cytometry were used to demonstrate that the SF-loaded mPEG–PCL could be efficiently inducing apoptosis in MCF-7 cell line.

Conclusion: We achieved to a successful formulation of SF-loaded m-PEG/PCL micelles in this study. Based on the cytotoxicity results of mPEG–PCL micelles against human breast cancer cell line (MCF-7) in this study, it suggested that SF/mPEG–PCL micelles can be an effective breast cancer treatment strategy in the future.

Keywords:

• d,l-Sulforaphane
• drug delivery
• micelles
• mPEG
• PCL

Declaration of interest

The authors report no declarations of interest. This work has been supported financially by Faculty of Pharmacy, Zanjan University of Medical Sciences, Zanjan, Iran.