Intracellular Delivery of ERBB2 siRNA and p53 Gene Synergistically Inhibits the Growth of Established Tumor in an Immunocompetent Mouse

Abstract

Breast cancer is one of the leading causes of deaths worldwide in women with hormone therapy, chemotherapy, targeted therapies, or their combinations being the current options for treating the disease at the different stages (stages I-III) with associated side-effects or increasing life-span at the advanced stage (stage IV). Small interfering RNA (siRNA) as an effective tool to selectively knockdown of a particular gene could be harnessed in combination with plasmid DNA (carrying a gene of interest) and conventional anti-cancer drugs for precisely treating breast cancer with minimal side effects. However the limitation of the naked siRNA and DNA in penetrating the plasma membrane and their sensitiveness to nuclease-mediated cleavage render the technology rather complex in therapeutic intervention. Recently, we have developed pH-sensitive carbonate apatite as a potential nano-carrier to efficiently deliver siRNA or DNA across the cell membrane and facilitate them to escape endosomal acidic compartment resulting in specific cleavage of a particular mRNA transcript or expression of a desirable protein, respectively. Moreover, we demonstrated nanoparticle-assisted delivery of the siRNAs targeting cyclin B1, PLCgamma- 2/calmodulin1, NFκB1/NFκB2, ABCG2/ABCB1 and cROS1 mRNAs sensitizes cervical adenocarcinoma and breast cancer cells towards traditional anti-cancer drugs. Here, we report that co-delivery of the siRNA targeting HER2/ErbB2 gene transcript and p53 gene with the help of carbonate apatite nanoparticles synergistically induces inhibition of growth/proliferation of breast cancer cell lines as well as regression of the breast tumor induced in Balb/c mice. Additionally, combined delivery of nanoparticle-associated HER2/ErbB2 siRNA and p53 gene apparently slows down the growth of the established tumor in presence of doxorubicin or paclitaxel compared with the individual free drugs. Thus, the combination of HER2/ErbB2 knockdown and restoring of normal p53 function could be a highly promising approach necessitating further studies through pre-clinical trials with different models of breast cancer to establish the therapeutic role of this combination therapy prior to conducting clinical trials in breast cancer patients.