Organic
isothiocyanates (ITCs) are dietary components present in cruciferous vegetables. The purpose of this investigation was to examine the cytotoxicity of 1-naphthyl
isothiocyanate (NITC),
benzyl isothiocyanate (BITC), beta-
phenethyl isothiocyanate (
PEITC), and
sulforaphane in human
breast cancer MCF-7 and human mammary epithelium MCF-12A cell lines, as well as in a second human epithelial cell line, human kidney HK-2 cells. The cytotoxicity of NITC, BITC,
PEITC, and
sulforaphane, as well as the cytotoxicity of the chemotherapeutic agents
daunomycin (DNM) and
vinblastine (VBL), were examined in MCF-7/sensitive (wt), MCF-7/Adr (which overexpresses
P-glycoprotein), MCF-12A, and HK-2 cells. Cell growth was determined by a
sulforhodamine B assay. The IC50 values for DNM and VBL in MCF-7/Adr cells were 7.12 +/- 0.42 microM and 0.106 +/- 0.004 microM (mean +/- SE) following a 48-hr exposure; IC50 values for BITC,
PEITC, NITC, and
sulforaphane were 5.95 +/- 0.10, 7.32 +/- 0.25, 77.9 +/- 8.03, and 13.7 +/- 0.82 microM, respectively, with similar values obtained in MCF-7/wt cells. Corresponding values for BITC,
PEITC, NITC, and
sulforaphane in MCF-12A cells were 8.07 +/- 0.29, 7.71 +/- 0.07, 33.6 +/- 1.69, and 40.5 +/- 1.25 microM, respectively. BITC and
PEITC can inhibit the growth of human
breast cancer cells as well as human mammary epithelium cells at concentrations similar to those of the chemotherapeutic
drug DNM.
Sulforaphane and NITC exhibited higher IC50 values. The effect of these ITCs on cell growth may contribute to the
cancer chemopreventive properties of ITCs by suppressing the growth of preclinical
tumors, and may indicate a potential use of these compounds as chemotherapeutic agents in
cancer treatment.