Antiproliferative effects of [D-Pro2, D-Trp7,9]-Substance P and aprepitant on several cancer cell lines and their selectivity in comparison to normal cells

A neuropeptide, Substance P (SP), has mitogenic action in many types of cancer cells mediated via the neurokinin-1 receptor (NK1R). Small molecular NK1R antagonists have been frequently shown to possess anticancer activity both in vivo and in vitro, but there are only a few papers on such activity regarding peptide antagonists. In order to extend the data on this class of compounds, we have compared the effects of a peptide antagonist, [D-Pro2, D-Trp7,9]-Substance P, and a small molecular antagonist, aprepitant on the proliferation of five cancer and three normal cell lines. The comparison was based on three assays: cell proliferation test, MTT test and assay for colony formation. Consistently with earlier reports, aprepitant potently reduced cell proliferation in cancer cell lines in all assays, but in contrast to previous works, the compound was not selective and it affected normal cell lines to a similar degree. The studied peptide antagonist, [D-Pro2, D-Trp7,9]-Substance P, was able to decrease proliferation only in a few cell lines, and only in the highest concentration (100 µM). In a lower concentration, a slight pro-proliferative effect was observed in a few cell lines. No statistically significant effects on colony formation were found for this compound.