Epidermal growth factor receptor targeted methotrexate and small interfering RNA co-delivery

Developing new drug delivery carriers addressing chemoresistance is still full of challenges and opportunities. As the rapid development of small interfering RNA (siRNA) provides promising therapeutic perspectives, nanocarriers for drug and siRNA co-delivery present new alternatives for cancer therapy.

A co-delivery nanosystem for methotrexate (MTX) or gamma-glutamylated derivatives (gE₂ -MTX and gE₅ -MTX) and antitumoral EG5 siRNA has been developed utilizing the sequence defined cationic lipo-oligomers 454, 1021 and 1027. Based on a lipo-oligomer-MTX-siRNA core, an epidermal growth factor receptor (EGFR) targeted delivery system was established via post modification with the GE11 targeting peptide.

Almost 100% MTX derivative incorporation was achieved in gE₂ -MTX or gE₅ -MTX siRNA/454 polyplexes, whereas the particle sizes (100-150 nm) and siRNA binding abilities were well maintained. Our co-delivery system greatly increased the MTX sensitivity of MTX resistant KB cells. Enhanced cellular internalization of GE11 siRNA/454 polyplexes incorporating either gE₂ -MTX or gE₅ -MTX was observed and attributed to GE11-mediated targeting of EGFR overexpressing KB cells. GE11 modified gE₂ -MTX or gE₅ -MTX EG5 siRNA polyplexes illustrated the highest anti-tumoral activities compared to free MTX or nontargeted polyplexes. The His-containing gE₂ -MTX or gE₅ -MTX siRNA/1027 polyplexes showed increased tumor cell killing compared to the His-free analogous 1021 polyplexes.

A new strategy for co-delivering negatively charged MTX and cytotoxic siRNA has been developed by utilizing sequence defined cationic lipo-oligomers. Mediated by the combined effect of antifolate MTX, antimitotic EG5 siRNA and EGFR targeting by GE11, superior tumor cell killing was obtained with GE11 gE₂ -MTX or gE₅ -MTX EG5 siRNA/454 polyplexes.