Cell death induction in breast cancer cells with nanoparticle-facilitated delivery of classical anti-cancer drugs and siRNAs targeting growth factor receptor and multi-drug transporter genes

Abstract

Cancer is the foremost cause of deaths worldwide with breast cancer being second among them [1]. Chemotherapy is the most preferred treatment tactic to treat breast cancer that is associated with copious adverse effects [2, 3] mainly caused by nonspecific targets of cancer drugs affecting highly dividing healthy cells of the body. In addition, development of resistance by cancer cells to these chemotherapeutic drugs is one of the most difficult obstacles to the clinical success of the therapy [4-6]. The classical chemical drugs most frequently used nowadays enter the cells either via the direct diffusion or the facilitated passive diffusion which is recognized by the cellular pump system [7-12]. The transporter molecules efflux drugs out of the cells decreasing drug accumulation inside the cells and causing them to acquire resistance to these drugs. In addition, cancer cells may accomplish resistance by changing the expression pattern of importer molecules that help drugs to get into the cells [13]. Furthermore, many growth factor receptors (GFRs) typically human epidermal growth factor receptors (EGFR1 and ERBB2) and insulin-like growth factor receptor (IGFR1) are overexpressed on breast cancer cells and thus influence their growth and proliferation [14] leading to tumor progression and conferring more resistance to drugs [15-18]. Designing smart carrier molecules to carry the widely used classical anticancer drugs inside the cells might help circumvent the recognition by the transporter molecules and thus enable more drugs accumulation into cells to exert more therapeutic efficacy. In addition, silencing of the transporter or GFR genes with small interfering RNAs (siRNAs) following their intracellular delivery along with drugs using an appropriate carrier molecule could be a novel approach to combat against cancer and acquired resistance more effectively. Targeted delivery of multiple siRNAs and drugs to cells could be facilitated with recently developed pH sensitive inorganic carbonate apatite nanoparticles [19-23]. These original and modified nanoparticles have been used for this study to carry the classical anti-cancer drugs (doxorubicin; Dox, methotrexate; Mtx, cyclophosphamide; Cyp and furouracil; FU) and siRNAs against GFR genes (EGFR1, ERBB2 and IGFR1) and ABC transporter genes (ABCB1, ABCG2 and ABCC1) to induce cellular cytotoxicity in human (MCF-7, MDA-MB-231) and mouse (4T1) breast cancer cell lines as well as in 4T1-induced mouse tumors. Nanoparticle complexed drug induced more cytotoxicity and tumour reduction by more cellular accumulation of drugs inside cells and co-delivery of drug and siRNAs against transporter and GFR genes via these nanoparticles induce additional cytotoxicity tumour reduction in mice