Targeting melanoma with peptide-conjugated nanoparticles

Source: nanotechweb.org, July 2015

Ultrasmall gold nanoparticles (<3 nm in diameter) are a promising therapeutic platform for cancer treatment due to their ability to accumulate in the nuclei of cells. Once inside cells, the nanoparticles can effectively deliver anticancer agents and simultaneously be used in radiotherapy for dose enhancement. However, achieving accumulation and retention of nanoparticles in tumours from systemic administration remains a challenge. In a new study reported in Nanotechnology, researchers compare the active and passive targeting of ultrasmall gold nanoparticles in a melanoma animal model.

The researchers compare two peptides for active targeting to melanoma tumours: a cyclic arginine–glycine–aspartic acid (RGD) peptide, previously shown to target cancer cells, and a novel peptide derived from the myxoma virus. The study shows that peptide conjugation changes the pattern of uptake of the nanoparticles by the cells. Rather than enter the nucleus, the peptide-coated particles cluster around the cell nuclei.

Tumour accumulation

In the mouse model, peptide conjugation improves the tumour accumulation of the nanoparticles, while the addition of a polyethylene glycol (PEG) coating increases the time the particles remain in the bloodstream. When peptide targeting and PEGylation are combined, the tumour accumulation improves with one peptide but not the other.

Passive and active targeting

The researchers conclude that the effect of passive targeting by PEGylation and active targeting by peptides can be independent or combined. New nanosystems for targeted therapies therefore need to be evaluated on a case-by-case basis.