Abstract
Purpose :
Cancer stem cells (CSCs) in all tumors including Retinoblastoma (Rb) are known to be chemoresistant and lead to tumor relapse after treatment in addition to being tumorigenic and metastatic in nature. Our previous studies identified CD133lo subset to be the CSCs in primary tumor as well as in Rb Y79 cell line. In this study, we aimed to evaluate the cytotoxicity of nanoformulated cancer drugs (Carboplatin and Etoposide) using lactoferrin protein nanoparticlesinY79Rb cell line and CD133sorted populations.
Methods :
Carboplatin and Etoposide loaded nanoparticles were prepared using the solution-oil chemistry based method. The drug and lactoferrin were measured 1:4 ratio, dissolved in PBS and incubated on ice for 60 min. 25ml of olive oil was added and further incubated on ice for 30min. After sonication for 15min at 60Amp, the mixture was frozen in liquid N2 for 10min and immediately transferred to 4oC for 4hrs. The pellet obtained on centrifugation was resuspended in 500µlPBS, characterized using SEM and measured for drug release efficiency using HPLC. Cytotoxicity of the standard and nanoformulated drugs was evaluated by MTT assay in total Y79 cellsand CD133 sorted subsets (CSCs and non-CSCs) with an exposure period of 48 hrs.
Results :
Carboplatin and Etoposide loaded lactoferrin protein nanoparticles measured 60±10 nm, 45±10nm and 25±5nm respectively. Drug loading efficiency of Carboplatin and Etoposide release in pH-5.2 was 60+5 and 48+5 respectively. The efficiency of nanoformulations of both the drugs had higher efficacy in all the three populations (p<0.05) starting with 50µM dose. CD133lo cells which constituted 15±0.6% of total population exhibited lower drug cytotoxicity as compared to total and non-CSCs (CD133hi) cells (p<0.05).
Conclusions :
This study provides evidence of higher cytotoxic efficacy of nanoformulated Carboplatin and Etoposide on Rb Y79 cell lines as compared to the standard soluble formulation in-vitro.Evidence of lower cytotoxic effect of drugs on CD133lo as compared toCD133hipoints towards chemoresistance, s characteristic of CSCs, in CD133lo population cells in Rb cell line, thus supporting our earlier studies. Further validation using combination and in-vivo testing are warranted to pave way for potential clinical application.
This is an abstract that was submitted for the 2018 ARVO Annual Meeting, held in Honolulu, Hawaii, April 29 - May 3, 2018.