Abstract

Introduction: Doxorubicin hydrochloride (Dox-HCl) is a widely prescribed anti-cancer drug for the treatment of breast cancer. However, the clinical application of Dox-HCl is constrained, especially in triple-negative breast cancer (TNBC) due to its toxicity and the aggressiveness of the tumour. Meanwhile, microRNA-145 (miR-145) is known to be a tumour suppressor miRNA (tsmiRs) exhibiting anti-proliferative and anti-metastasis effect against various cancers. However, there is no evidence delineating the combination use of miR-145 mimics with Dox-HCl co-loaded in nanoparticles that increases the therapeutic efficacy on TNBC when compared to individual or combinational treatment without nano-carrier. The aim of this study is to synthesise and characterise Dox-HCl and miR-145 mimics co-loaded in PEGylated liposome and to investigate its in vitro anti-proliferative activity against MDA-MB-231 cells. Methods:  Dox-HCl and miR-145 mimics co-loaded in PEGylated liposomes were formulated according to composite central design. Response models were developed to investigate the correlation of formulation parameters toward nanoparticle size (d.nm)  and encapsulation efficiency (EE%) of both Dox-HCl and miR-145 mimics. The ideal liposome formulation was further characterised for its in vitro stability, drug release, cellular uptake, and cellular toxicity. Results: Statistical analysis of the response models indicated that formulation 6 (F6) exhibited the highest desirability function (D=0.934) with optimum nanoparticle size (137.1±0.4d. nm) and high EE% for both Dox-HCl (67.31±3.76%) and miR-145 mimics (87.85±4.60%). F6 displayed great stability over 60 days at 4°C with stable nanoparticle size and zeta potential (p<0.05), while the EE% of Dox-HCl and miR-145 mimics were 94.97±0.53% and 51.96±2.67%, respectively. At 48 hours, F6 displayed increased in vitro cellular uptake at 1.3 folds along with maximal drug release, which correlate to its higher toxicity (IC50=0.58±0.02µM) against MDA-MB-231 cells than the free regimen (IC50=1.03±0.07µM).  Conclusion: The current findings suggest that PEGylated liposome shows potential in targeted delivery of anti-cancer drugs and therapeutic miRNAs into tumour cells, hence warrant further investigation. 

Keywords: Breast cancer, Tumour suppressing miRNAs, Dox-HCl, Liposome, Nanoparticles