Kimura K, Gelmann E P
Department of Oncology, Lombardi Cancer Center, Georgetown University, 3800 Reservoir Rd, NW Washington, DC 20007-2197, USA.
Cell Death Differ. 2002 Sep;9(9):972-80. doi: 10.1038/sj.cdd.4401049.
LNCaP prostate cancer cells are resistant to induction of apoptosis by gamma-irradiation and partially sensitive to TNF-alpha or FAS antibody, irradiation sensitizes cells to apoptosis induced by FAS antibody or TNF-alpha. LNCaP cell clones stably expressing IkappaBalpha super repressor were resistant to apoptosis induced by death ligands in the presence or absence of irradiation. IkappaBalpha super repressor expression also increased clonogenic survival after exposure to TNF-alpha+irradiation, but had no effect on survival after irradiation alone. IkappaBalpha super repressor expression blocked the increase of whole cell and cell surface FAS expression induced by TNF-alpha, but did not effect induction of FAS expression and cell surface FAS expression that resulted from irradiation. In cells expressing IkappaBalpha super repressor there was diminished activation of caspases-8 and -7 and diminished production of proscaspases-8 and -7, usually required for death induction in LNCaP cells. Peptide inhibitors of caspase activation complemented the IkappaBalpha super repressor inhibition of apoptosis, but peptide inhibitors of serine proteases had no effect on LNCaP cells expressing IkappaBalpha super repressor. Moreover, cleavage of a serine protease substrate was induced by treatment of LNCaP cells with TNF-alpha and irradiation. The data suggest that in LNCaP cells NF-kappaB mediates a proapoptotic pathway that leads to activation of proapoptotic serine proteases.
LNCaP前列腺癌细胞对γ射线诱导的凋亡具有抗性，对TNF-α或FAS抗体部分敏感，照射可使细胞对FAS抗体或TNF-α诱导的凋亡敏感。稳定表达IkappaBalpha超级阻遏物的LNCaP细胞克隆在有或无照射的情况下对死亡配体诱导的凋亡具有抗性。IkappaBalpha超级阻遏物的表达在暴露于TNF-α+照射后也增加了克隆形成存活率，但对单独照射后的存活率没有影响。IkappaBalpha超级阻遏物的表达阻断了TNF-α诱导的全细胞和细胞表面FAS表达的增加，但不影响照射导致的FAS表达诱导和细胞表面FAS表达。在表达IkappaBalpha超级阻遏物的细胞中，caspases-8和-7的激活减少，proscaspases-8和-7的产生减少，而这通常是LNCaP细胞死亡诱导所必需的。caspase激活的肽抑制剂补充了IkappaBalpha超级阻遏物对凋亡的抑制作用，但丝氨酸蛋白酶的肽抑制剂对表达IkappaBalpha超级阻遏物的LNCaP细胞没有影响。此外，用TNF-α和照射处理LNCaP细胞可诱导丝氨酸蛋白酶底物的裂解。数据表明，在LNCaP细胞中，NF-κB介导了一条导致促凋亡丝氨酸蛋白酶激活的促凋亡途径。
