Sigma ligands inhibit the growth of small cell lung cancer cells

The effects of sigma ligands on small cell lung cancer (SCLC) cells were in vestigated. I-125-N-(2-(piperidino)ethyl)-2-iodobenazmide (2-IBP) bound wit h high affinity to SCLC cell line NCl-H209 and NCl-N417. Specific I-125-2-I BP binding was inhibited with high affinity by ifendipine, haloperidol, (2- piperidinyl-aminoethyl)-4-iodobenzamide (IPAB) and 1,3-ditolylguanidine (DT G) with IC50 values of 3, 10, 15 and 90 nM respectively. In vitro, 10 mu M 2-IBP, haloperidol or IPAB inhibited NCl-N417 proliferation using a MTT or clonogenic assay. In vivo, 4 mg/kg IPAB or 2-IBP inhibited NCl-N417 xenogra ft proliferation. I-125-2-IBP localized to the SCLC tumors after subcutaneo us injection. These results suggest that sigma ligands may be utilized to l ocalize and inhibit the proliferation of SCLC tumors.