Enhanced noscapine delivery using estrogen-receptor-targeted nanoparticles for breast cancer therapy.

Noscapine (Nos), an orally available plant-derived antitussive alkaloid, is in phase II clinical trials for cancer chemotherapy. It has extensively been shown to inhibit tumor growth in nude mice bearing human xenografts of hematopoietic, breast, lung, ovarian, brain, and prostate origin. However, high tumor-suppressive Nos dosages encumber the development of oral controlled-release formulations because of a short biological half-life (<2 h), poor absorption, low aqueous solubility, and extensive first-pass metabolism. Here, we present the design, fabrication, optimization, characterization, and biological evaluation of estrone-conjugated noscapine-loaded gelatin nanoparticles (Nos-ES-GN) for targeting estrogen-receptor-positive breast cancer MCF-7 cells. Gelatin nanoparticles (GN) were a uniformly compact size, stable at physiological pH, and showed a drug entrapment efficiency of 66.1±5.9 and 65.2±5.6% for Nos-GN and Nos-ES-GN, respectively. The secondary structure of gelatin nanocoacervates was predicted using circular dichroism and in-silico molecular modeling. Our data suggest that ethanol-fabricated GN retained the α-helical content of gelatin, whereas acetone favored the formation of random coils. The conjugation of estrone to Nos-GN did not affect the release rate of the drug, and both formulations followed first-order release kinetics with an initial burst, followed by a slow release. The IC50 value of Nos-ES-GN was 21.2 μmol/l, which was ∼50% lower than the free drug (43.3 μmol/l), suggesting targeted drug delivery. Our cell uptake study carried out in an estrogen-receptor-positive (MCF-7) and negative (MDA-MB-231) cancer cell lines showed greater accumulation of Nos-ES-GN in MCF-7 cells instead of MDA-MB-231 cells. Our data indicated that estrone-conjugated nanoparticles may potentially be used for targeting breast cancer cells.