Quick synthesis of a novel combinatorial delivery system of siRNA and doxorubicin for a synergistic anticancer effect

: Purpose: Combining siRNA and other chemotherapeutic agents into one nanocarrier can overcome the multidrug resistance (MDR) phenomenon by synergistically MDR relative genes silencing and elevated chemotherapeutic activity. Most of these systems are typically fabricated through complicated procedures, which involves materials preparation, drug loading and modifications. Herein, the purpose of this study is to develop a new and fast co-delivery system of siRNA and doxorubicin for potentially synergistic cancer treatment. Methods: The co-delivery system is constructed conveniently by a stable complex consisting of doxorubicin bound to siRNA via intercalation firstly, followed by interacting with (3-Aminopropyl)triethoxysilane (APTES) electrostatically and Tetraethyl orthosilicate (TEOS) co-condensed, and the characterizations of the resultant nanocarrier are also investigated. Furthermore, this study evaluates the synergistic anti-cancer efficacy in MCF-7/MDR cells after treatment of siRNA and doxorubicin 'two in one' nanocarriers. Results: We establish a new and fast method to craft a co-delivery system of siRNA and doxorubicin with controllable and nearly uniform size, and the entire fabrication process only costs in about 10 minutes. The resultant co-delivery system presents high loading capacities of siRNA and doxorubicin, and the encapsulated doxorubicin plays a pH-responsive control release. Further, biological functionality tests of the synthesized co-delivery nanocarriers show high inhibition of P-gp protein encoded by MDR-1 gene in MCF-7/MDR cells (a variant of human breast cancer cell line with drug resistance) after transfection of these nanocarriers carrying MDR-1 siRNA and doxorubicin simultaneously, which sensitize the MCF-7/MDR cells to doxorubicin, overall leading to improved cell suppression. Conclusion: Collectively, this co-delivery system not only serves as potent therapeutics for synergistic cancer therapy, it also may facilitate the bench-to-bedside translation of combinatorial delivery system as a robust drug nanocarrier by allowing for fabricating a simply and fast nanocarrier for co-delivery of siRNA and doxorubicin with predictable high production rate.