Abstract 2268: Intracellular delivery of RGDfk grafted docetaxel encapsulated PLGA nanoparticles for breast cancer therapy

Abstract

Abstract The purpose of the study was to prepare, characterized, assess in vitro antiproliferative activity, and determine DNA content and mode of cell death of RGDfk grafted Docetaxel encapsulated PLGA nanoparticles on breast cancer cells. DC- encapsulated nanoparticles were prepared using solvent evaporation technique. RGD-conjugation was done by carbodiimide coupling method. The nanoparticles were characterized for particle size and zeta potential by zeta sizer (Nano-ZS), entrapment efficiency and in-vitro drug release profile and RGD-conjugation efficiency. To establish antiproliferative effect, the RGD-conjugated nanoparticles of DC(PLGA-DC-RGD), unconjugated nanoparticles (PLGA-DC) and equal amounts of the free drug were studied on BT-20 and MDA-MB-231 cells by CCK-8 assay method. DNA content analysis was done on flowcytometry by propadium iodide staining. The mode of cell death at different time and concentration was determined by FITC-Annexine V assay. The DC encapsulated RGD conjugated and unconjugated PLGA nanoparticles were found to be nanosized. The cytotoxicity indicated by IC50 values suggests that RGD conjugated nanoparticles at 72hrs are 2.1 and 4 times more cytotoxic than unconjugated nanoparticles and drug solution for BT-20 cell lines. Similarly, for MDA-MB-231 cells, the RGD conjugated nanoparticles are 2 and 4 time more cytotoxic than unconjugated nanoparticles and drug solution. The results shows that the RGD conjugated nanoparticles at the concentration of 5nM showed 51% G2 phase arrest as compared to 30% G2 phase arrest with unconjugated nanoparticles at the same concentration at 24hrs. Two types of mode of cell death were found during the FITC-Annexin V assay. At 24 hrs, the treatment of 5nM of drug solution with cells resulted in 13.6% & 3.4 % necrotic & apoptotic cell fragments respectively. While at similar drug equivalent concentration, the PLGA-DC-RGD and PLGA-DC nanoparticles showed 6.4% & 28.3% and 5.1% & 25.6% necrotic & apoptotic cell fragments respectively. With increase in time and concentration the mode of cell death by apoptosis was found to be increasing. To conclude, RGD conjugation to nanoparticles improved antiproliferative activity when assessed in vitro in breast cancer cell lines compared to free drug and unconjugated nanoparticles. The DNA content analysis depicted the cell cycle arrest in G2 phase was more even at lower drug equivalent concentration of PLGA-RGD. The mode of cell death was found to be mainly by necrosis at low drug equivalent concentration (1nM) and by apoptosis at high drug equivalent concentration (10nM) of RGD conjugated drug encapsulated nanoparticles for breast cancer cell lines. Hence, it may be concluded that drug nanocarriers once conjugated with RGD can provide prolonged drug release to cytoplasm and can affectively target breast cancer and can probably reduce the limitations associated with breast cancer chemotherapy. Note: This abstract was not presented at the AACR 101st Annual Meeting 2010 because the presenter was unable to attend. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 2268.