Abstract
Background:
RET/PTC1
is the most prevalent type of gene rearrangement found in papillary thyroid carcinoma (PTC). Previously, we introduced a new noncationic nanosystem for targeted
RET/PTC1
silencing by efficient delivery of small interfering RNA (siRNA) using the “squalenoylation” approach. With the aim of improving these results further, we designed new squalenoyl nanostructures consisting of the fusogenic peptide GALA-cholesterol (GALA-Chol) and squalene (SQ) nanoparticles (NPs) of siRNA RET/PTC1.
Methods:
The siRNA RET/PTC1–SQ bioconjugate was synthesized. The corresponding NPs were prepared with or without GALA-Chol by nanoprecipitation and then characterized for their size and zeta potential. The effects of NPs on BHP 10-3 SC
mice
and TPC-1 cell viability (MTT assay), gene and protein silencing (reverse transcription–quantitative polymerase chain reaction [rt-qPCR], Western blot), and cellular uptake (fluorescent microscopy) were studied.
In vivo
gene silencing efficiency of siRNA RET/PTC1–SQ NPs was assessed by administration in nude mice via either intratumoral (i.t.) or intravenous (i.v.) routes. Tumor growth was followed for 19 days. Tumors were then collected, and RET/PTC1 gene and protein inhibitions were assessed by RT-qPCR and Western blot.
Results:
The combination of siRNA RET/PTC1–SQ bioconjugate and GALA-Chol leads to stable NPs of ∼200 nm diameter.
In vitro
, the results revealed that combining GALA-Chol with siRNA RET/PTC1–SQ NPs decreased cell viability, enhanced cellular internalization, and induced gene silencing efficiency in both human PTC (BHP 10-3 SC
mice
and TPC-1) cell lines. On the contrary,
in vivo
, the siRNA RET/PTC1–SQ GALA-Chol NPs were not found to be efficient either in gene silencing or in tumor growth inhibition, compared to siRNA RET/PTC1–SQ NPs both via i.t. and i.v. routes (
p
<0.001).
Conclusions:
Conversely to siRNA RET/PTC1–SQ NPs, the siRNA RET/PTC1–SQ GALA-Chol NPs are efficient
in vitro
but not
in vivo
. Finally, NPs of siRNA RET/PTC1–SQ were found to be efficient silencers of the
RET/PTC1
fusion oncogene in
in vivo
applications even at a concentration lower than used in a previously published study.