INDUCTION OF INTRACELLULAR DEATH OF BREAST CANCER CELLS THROUGH COMBINED INTRACELLULAR DELIVERY OF A TUMOR-SUPPRESSOR GENE AND SMALL INTERFERING RNAS AGAINST GROWTH FACTOR RECEPTOR AND ANTI-APOPTOTIC GENES

Abstract

Breast cancer is one of the most common malignancies in women. It continues to be a major burden and cause of death among women worldwide. Current treatment strategies for metastatic breast cancer (MBC) depend upon patient and tumor classification; menopausal status, hormone receptor status, and HER-2 status, together with the site of metastatic disease (bone or soft tissue). The choice of treatment in metastatic disease usually involves systemic endocrine therapy or cytotoxic chemotherapy, with an anti–HER-2 agent when appropriate. Novel agents are necessary in this field because many of the current therapies used in breast cancer therapy have limitations. These include drug resistance, lack of target receptor expression in tumors (e.g., only 25% of breast cancer tumors have HER-2 expression), lack of specificity and relatively small improvements in survival etc. Advances in the understanding of the etiology and biology of breast cancer have identified key targets among the multiple signaling pathways involved in the development, growth, and survival of breast cancer cells. As such, targeted therapies are among the most promising new agents for the treatment of breast cancer. One of the promising approaches in this field is tumor-directed delivery of genes and gene silencing nucleic acid sequences to inhibit cancer cell proliferation and to induce apoptosis. Both genetic and chemical engineering approaches enabled production of a lot of vital and non-viral carriers for targeted delivery. However, considering the issue of human safety, viral vectors are not suitable candidates for clinical uses although they are very efficient for intracellular delivery of genes and gene silencing elements. We have successfully developed an efficient non-viral vector system carbonate apatite nanoparticle which is more superior to contemporary vectors used, especially for transfecting at lower concentrations of siRNA. By employing carbonate apatite nanoparticles, we proved that co- delivery of siRNAs, p53 gene and anti-cancer drugs managed to block the signalling pathways. Simultaneous delivery of siRNAs-EGFR, IGFR, ERBB2, BCL2 and p53 gene together with anticancer drugs- Cisplatin, Doxorubicin and Paclitaxel by carbonate apatite exhibited better effects in invitro and invivo studies in comparison with the anticancer alone treated groups where the cell viability and tumor growth was significantly reduced to show more sensitivity towards the drug. In conclusion the study proved that efficient delivery of p53 gene together with the siRNAs against the growth factor receptor genes and anti-apoptotic gene using carbonate apatite nanoparticle would effectively kill the breast cancer cells and the synergistic effect produced by p53 gene together with siRNAs against the growth factor receptor genes and anti-apoptotic gene and various anti-cancer drugs provided a new insight in the treatment protocol of breast cancer. The successful therapeutic combinations identified through the study will significantly accelerate the identification and validation of targets for breast cancer therapy.