Combination therapy with bioengineered miR-34a prodrug and doxorubicin synergistically suppresses osteosarcoma growth

Abstract

Osteosarcoma (OS) is the most common form of primary malignant bone tumor and prevalent among children and young adults. Recently we have established a novel approach to bioengineering large quantity of microRNA-34a (miR-34a) prodrug for miRNA replacement therapy. This study is to evaluate combination treatment with miR-34a prodrug and doxorubicin, which may synergistically suppress human OS cell growth via RNA interference and DNA intercalation. Synergistic effects were indeed obvious between miR-34a prodrug and doxorubicin for the suppression of OS cell proliferation, as defined by Chou-Talalay method. The strongest antiproliferative synergism was achieved when both agents were administered simultaneously to the cells at early stage, which was associated with much greater degrees of late apoptosis, necrosis, and G2 cell cycle arrest. Alteration of OS cellular processes and invasion capacity was linked to the reduction of protein levels of miR-34a targeted (proto-)oncogenes including SIRT1, c-MET, and CDK6. Moreover, orthotopic OS xenograft tumor growth was repressed to a significantly greater degree in mouse models when miR-34a prodrug and doxorubicin were co-administered intravenously. In addition, multiple doses of miR-34a prodrug and doxorubicin had no or minimal effects on mouse blood chemistry profiles. The results demonstrate that combination of doxorubicin chemotherapy and miR-34a replacement therapy produces synergistic antiproliferative effects and it is more effective than monotherapy in suppressing OS xenograft tumor growth. These findings support the development of mechanism-based combination therapy to combat OS and bioengineered miR-34a prodrug represents a new natural miRNA agent.

Bioengineered non-coding RNA agent (BERA) in action

“…In addition, systemic co-administration of bioengineered miR-34a prodrug and doxorubicin was revealed to be more effective than single drug treatment to control tumor growth in an orthotopic osteosarcoma xenograft mouse model. 44 These findings support the use of biological ncRNAs as novel prodrugs for monotherapy or combination therapy.…”

“…37,38 In addition, recombinant ncRNAs from, such as the siRNAs isolated from p19 complex and miRNAs/ siRNAs from OnRS platform (Table 1), are biologically active in the regulation of target gene expression in mammalian cells, which have been demonstrated in many studies. 22,34,35,40,43,44 Specifically, bioengineered tRNA/ mir-27b was found to be processed to mature miR-27b in human carcinoma cells, which consequently reduced CYP3A4 protein expression and led to a lower midazolam 1'-hydroxylase activity. 35 The tRNA/mir-1291 was readily processed to mature miR-1291 in breast cancer MCF-7 cells and pancreatic cancer PANC-1 cells.…”

“…As an example, strong synergistic effects in the suppression of osteosarcoma cell proliferation were demonstrated for bioengineered tRNA/mir-34a and doxorubicin, a DNA intercalator. 44 Much greater degrees of late apoptosis, necrosis, and G2 cell cycle arrest as well as suppression of miR-34a target gene expression were also elucidated for combination therapy. In addition, systemic co-administration of bioengineered miR-34a prodrug and doxorubicin was revealed to be more effective than single drug treatment to control tumor growth in an orthotopic osteosarcoma xenograft mouse model.…”

MicroRNA Pharmacoepigenetics: Posttranscriptional Regulation Mechanisms behind Variable Drug Disposition and Strategy to Develop More Effective Therapy

“…MicroRNAs are able to suppress the expression of some efflux transporters and enzymes and lead to a greater degree of intracellular drug accumulation, resulting in higher efficacy (Zhu et al, 2008;Pan et al, 2009g;Liang et al, 2010;Pan et al, 2013;Shang et al, 2014;Li et al, 2015). Meanwhile, some miRNAs may directly reduce the protein outcome of pharmacological targets [e.g., (proto)oncogenes] and thus control disease progression (e.g., tumor growth and metastasis) Zhao et al, 2015). However, research on miRNA pharmacoepigenetics and development of miRNA-based therapy may be limited by the utilization of synthetic miRNA agents consisting of excessive artificial modifications on the phosphate linkages and/or ribose rings and thus exhibit different physicochemical and biologic properties or toxicities.…”

“…MicroRNAs downregulate the expression of efflux transporters in tumor cells, resulting in a higher level of intracellular drug accumulation and thus an improved efficacy (Zhu et al, 2008;Pan et al, 2009g, 2013Liang et al, 2010;Shang et al, 2014;Li et al, 2015). In addition, miRNAs may directly target (proto-) oncogenes and thus additively or synergistically suppress tumor growth Zhao et al, 2015). Downloaded from a frequency greater than 5% among Caucasians, African Americans, and Asians, none of the inferred polymorphisms were located within or in proximity to the MRE sites for miR-124a and miR-506 and thus showed any significant effects on miR-124a-and miR-506-mediated regulation of ABCC4.…”