Antitumoral Action of the Neurokinin-1-Receptor Antagonist L-733,060 and Mitogenic Action of Substance P on Human Retinoblastoma Cell Lines

Abstract

Activation of the neurokinin-1 receptor is known to induce proliferation in tumor cells, but it is as yet unknown whether this applies to retinoblastoma. This was an in vitro study of the growth inhibitory capacity of the potent and long-acting neurokinin-1 receptor antagonist L-733,060, at concentrations ranging from 7.5 to 20 microM, against the human retinoblastoma line WERI-Rb-1 and from 10 to 25 microM against the human retinoblastoma line Y-79. The ability of substance P (an neurokinin-1 stimulator) to activate the cell growth of these retinoblastoma cell lines was also determined. A cell counter was used to determine the number of viable cells, followed by application of the tetrazolium compound WST-8 [2-(2-methoxy-4-nitrophenyl)-3-(4 nitrophenyl))-5-(2,4-disulfophenyl)-2H-tetrazolium, monosodium salt, colorimetric method to evaluate cell viability in this cytotoxicity assay. Nanomolar concentrations of substance P increased the growth of both cell lines and micromolar concentrations of L-733,060 inhibited the growth of the two cell lines studied, with and without previous administration of substance P. L-733,060 inhibited the growth of the WERI-Rb-1 and Y-79 cell lines in a dose-dependent manner. IC50 was 12.15 microM for 49 hours for WERI-Rb1 and 17.38 microM for 40 hours for Y-79. The findings demonstrate that substance P is a mitogen and also indicate that the neurokinin-1 receptor antagonist L-733,060 acts on both human retinoblastoma cell lines as an antitumoral agent.