Gefitinib, a selective EGFR tyrosine kinase inhibitor, induces apoptosis through activation of Bax in human gallbladder adenocarcinoma cells
Gefitinib, a selective EGFR tyrosine kinase inhibitor, induces apoptosis through activation of Bax in human gallbladder adenocarcinoma cells
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DOI：
10.1002/jcb.20678
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发表时间：
2006-03-01
影响因子：
4
通讯作者：
Nakano, S
中科院分区：
文献类型：
--
作者：
Ariyama, H;Qin, B;Nakano, S
虽然吉非替尼是一种表皮生长因子受体（EGFIR）酪氨酸激酶的选择性抑制剂，已被临床证明对某些类型的癌细胞有效，但其抗肿瘤活性的分子机制尚未完全阐明。在本研究中，我们研究了吉非替尼诱导HAG-1人胆囊腺癌细胞生长抑制和凋亡的机制。1 μ M剂量的吉非替尼对小鼠生长有明显抑制作用，培养72 h后细胞数量不可逆下降，120 h后凋亡细胞群逐渐扩大。治疗2小时后，吉非替尼显著抑制EGFR自磷酸化及随后通过Erk和Akt的下游信号通路，并在24小时诱导细胞在细胞周期的G0/G1期积累，同时p21转录增加，p27表达增加。吉非替尼不影响总和磷酸化的p53丝氨酸15的数量，但上调总Bax的表达，随后增加p18 Bax， Bax的活性形式。Bcl-2和Bad的表达没有变化。吉非替尼诱导的总Bax表达的增加可能是由于Bax的降解减少，因为吉非替尼治疗没有改变Bax mRNA的水平。吉非替尼促进线粒体富集部分全长p21 Bax裂解为p18 Bax，这是Bax向凋亡激活的一个特征。此外，使用抗Bax小干扰双链RNA （siRNA）阻断Bax可显著减少吉非替尼诱导的细胞凋亡。综上所述，这些数据表明p18 Bax在吉非替尼诱导的细胞凋亡中起关键作用。
Although gefitinib, a selective inhibitor of epidermal growth factor receptor (EGFIR) tyrosine kinase, has been clinically demonstrated to be effective for certain cancer cell types, the molecular mechanisms of the anti-tumor activity have not been fully elucidated. In this study, we investigated the mechanism of gefitinib-induced growth inhibition and apoptosis in HAG-1 human gallbladder adenocarcinoma cells. Treatment of gefitinib at a dose of 1 mu M resulted in a significant growth inhibition, and the cell number irreversibly declined after 72-h incubation, with a progressive expansion of apoptotic cell population over 120-h. Following 2-h treatment, gefitinib significantly inhibited EGFR autophosphorylation and subsequent downstream signaling pathway through Erk and Akt, and induced accumulation of cells in the G0/G1 phase of the cell cycle at 24-h, accompanied by a concomitant increase in p21 transcript and increased expression of p27. Gefitinib did not affect the amount of total and phosphorylated p53 at serine 15, but upregulated the expression of total Bax, with subsequent increase in p18 Bax, an active form of Bax. The expression of Bcl-2 and Bad was unchanged. An increase in gefitinib-induced expression of total Bax might be due to the decreased degradation of Bax, because the level of Bax mRNA has not been altered by gefitinib treatment. Gefitinib promoted the cleavage of full-length p21 Bax into p18 Bax in mitochondrial-enriched fraction, a characteristic feature of Bax activation toward apoptosis. Moreover, blockade of Bax by using anti-Bax small interfering double stranded RNA (siRNA) significantly reduced gefitinib-induced apoptosis. Taken together, these data suggest a critical role of p18 Bax in gefitinib-induced apoptosis.