Cuddihy Sarah L, Brown Kristin K, Thomson Susan J, Hampton Mark B
Free Radical Research Group, Department of Pathology, University of Otago, PO Box 4345, Christchurch, New Zealand.
Cancer Lett. 2008 Nov 28;271(2):215-21. doi: 10.1016/j.canlet.2008.06.002. Epub 2008 Jul 18.
Isothiocyanates are a class of phytochemicals able to induce apoptosis in numerous cells including Jurkat T-lymphoma cells overexpressing the oncoprotein Bcl-2. To test if isothiocyanates are also effective against other anti-apoptotic members of the Bcl-2 family we generated Jurkat cells stably overexpressing Bcl-X(L). Phenethyl isothiocyanate (PEITC) was cytotoxic to these cells, with an LD(50) ranging from 9 to 18 microM depending on the level of Bcl-X(L) expression. Apoptosis induction in response to PEITC was confirmed by caspase activation and phosphatidylserine exposure. Isothiocyanates specifically target cysteine residues, therefore we tested the hypothesis that PEITC directly impairs Bcl-2 and Bcl-X(L) activity by interacting with their conserved cysteine residues. Jurkat cells overexpressing double cysteine mutants of Bcl-2 were generated, but they remained sensitive to PEITC. We conclude that PEITC antagonizes the action of anti-apoptotic Bcl-2 family members via an indirect mechanism.
异硫氰酸盐是一类植物化学物质，能够在包括过表达癌蛋白Bcl-2的Jurkat T淋巴瘤细胞在内的众多细胞中诱导凋亡。为了测试异硫氰酸盐是否也对Bcl-2家族的其他抗凋亡成员有效，我们构建了稳定过表达Bcl-X(L)的Jurkat细胞。苯乙基异硫氰酸盐（PEITC）对这些细胞具有细胞毒性，其半数致死剂量（LD50）根据Bcl-X(L)的表达水平在9至18微摩尔之间。通过半胱天冬酶激活和磷脂酰丝氨酸暴露证实了PEITC诱导的凋亡。异硫氰酸盐特异性靶向半胱氨酸残基，因此我们测试了PEITC通过与其保守的半胱氨酸残基相互作用直接损害Bcl-2和Bcl-X(L)活性的假说。构建了过表达Bcl-2双半胱氨酸突变体的Jurkat细胞，但它们对PEITC仍然敏感。我们得出结论，PEITC通过间接机制拮抗抗凋亡Bcl-2家族成员的作用。
