Azuma M, Tamatani T, Ashida Y, Takashima R, Harada K, Sato M
Second Department of Oral and Maxillofacial Surgery and Oncology, Tokushima University School of Dentistry, 3 Kuramoto-cho, Tokushima 770-8504, Japan.
Oral Oncol. 2003 Apr;39(3):282-9. doi: 10.1016/s1368-8375(02)00116-1.
Cisplatin (CDDP) is a potent DNA-damaging anticancer agent, and its cytotoxic action is exerted by the induction of apoptosis. However, activation of the transcription factor NF-kappaB results in protection against apoptosis. We examined the molecular mechanisms involved in the induction of apoptosis by CDDP as regards both suppression of NF-kappaB and activation of caspases. Human oral squamous carcinoma cells (B88) were employed in this study. We found that CDDP treatment affected neither NF-kappaB activity nor the expression levels of antiapoptotic proteins, including TRAF-1, TRAF-2, and cFLIP, in B88 cells. However, two apoptosome molecules, cytochrome c and Apaf-1, were significantly augmented in the cytoplasm by CDDP treatment. Further, the activation of caspase-9 and caspase-3, downstream molecules leading to mitochondria-mediated apoptosis, were detected after treatment with CDDP. Finally, apoptosis was also clearly observed, as evidenced by cleavage of PARP through the activation of caspase-3. These findings suggest that CDDP exerts its apoptotic action by the mitochondria-mediated activation of caspases but not by the activation of caspases due to the inhibition of NF-kappaB activity that follows the suppression of antiapoptotic proteins.
顺铂（CDDP）是一种强效的DNA损伤抗癌药物，其细胞毒性作用通过诱导细胞凋亡来实现。然而，转录因子NF-κB的激活会导致对细胞凋亡的保护作用。我们研究了顺铂诱导细胞凋亡所涉及的分子机制，包括对NF-κB的抑制和半胱天冬酶的激活。本研究采用了人口腔鳞状癌细胞（B88）。我们发现，顺铂处理对B88细胞中的NF-κB活性以及包括TRAF-1、TRAF-2和cFLIP在内的抗凋亡蛋白的表达水平均无影响。然而，顺铂处理后，细胞质中的两种凋亡小体分子细胞色素c和凋亡蛋白酶激活因子-1（Apaf-1）显著增加。此外，在用顺铂处理后，检测到了导致线粒体介导的细胞凋亡的下游分子半胱天冬酶-9和半胱天冬酶-3的激活。最后，通过半胱天冬酶-3的激活导致聚（ADP-核糖）聚合酶（PARP）的裂解，也清楚地观察到了细胞凋亡。这些发现表明，顺铂通过线粒体介导的半胱天冬酶激活发挥其凋亡作用，而不是通过抑制抗凋亡蛋白后抑制NF-κB活性而导致的半胱天冬酶激活来发挥作用。
