Chou Yean-Hwei, Ho Yuan-Soon, Wu Chi-Chen, Chai Chiah-Yang, Chen Soul-Chin, Lee Chia-Hwa, Tsai Pei-Shan, Wu Chih-Hsiung
Department of Surgery, Division of General Surgery, School of Medicine, Taipei Medical University and Hospital, No. 252 Wu-Hsing Street, Taipei 110, Taiwan.
Food Chem Toxicol. 2007 Aug;45(8):1356-67. doi: 10.1016/j.fct.2007.01.012. Epub 2007 Jan 24.
Our studies demonstrated that human colon cancer cells (COLO 205), with higher expression level of check point kinase 1 (Chk1), were more sensitive to microtubule damage agent Tubulozole (TUBU) induced G2/M phase arrest than normal human colon epithelial (CRL) cells. TUBU (10 microM, for 3h) treatment resulted in rapid and sustained phosphorylation of Cdc25C (Ser-216) leading to increased 14-3-3beta binding. This resulted in increased nuclear translocation. In addition, TUBU induced phosphorylation of the Cdc25C (Ser-216) and Bad (Ser-155) proteins were blocked by Chk1 SiRNA-transfection. Surprisingly, cellular apotosis was observed in cells treated with TUBU after Chk1 SiRNA inhibition. We further demonstrated that extracellular signal-regulated kinase (ERK) activation by TUBU was needed for Chk1 kinase activation and microtubule formation as shown by the attenuation of these responses by the ERK1/2 specific inhibitor PD98059. However, TUBU induced ERK1/2 phosphorylation was not blocked in the Chk1 SiRNA-transfected COLO 205 cells. These results imply that ERK1/2 mediated Chk1 activation may be play an important role in determining TUBU induced G2/M arrest or apoptosis in COLO 205 cells.
我们的研究表明，与正常人结肠上皮（CRL）细胞相比，检查点激酶1（Chk1）表达水平较高的人结肠癌细胞（COLO 205）对微管损伤剂Tubulozole（TUBU）诱导的G2/M期阻滞更敏感。TUBU（10微摩尔，处理3小时）处理导致Cdc25C（Ser-216）快速且持续磷酸化，导致14-3-3β结合增加。这导致核转位增加。此外，Chk1 SiRNA转染可阻断TUBU诱导的Cdc25C（Ser-216）和Bad（Ser-155）蛋白磷酸化。令人惊讶的是，在Chk1 SiRNA抑制后用TUBU处理的细胞中观察到细胞凋亡。我们进一步证明，如ERK1/2特异性抑制剂PD98059减弱这些反应所示，TUBU激活细胞外信号调节激酶（ERK）对于Chk1激酶激活和微管形成是必需的。然而，在Chk1 SiRNA转染的COLO 205细胞中，TUBU诱导的ERK1/2磷酸化并未被阻断。这些结果表明，ERK1/2介导的Chk1激活可能在决定TUBU诱导的COLO 205细胞G2/M期阻滞或凋亡中起重要作用。
