Eto Kojiro, Iwatsuki Masaaki, Watanabe Masayuki, Ida Satoshi, Ishimoto Takatsugu, Iwagami Shiro, Baba Yoshifumi, Sakamoto Yasuo, Miyamoto Yuji, Yoshida Naoya, Baba Hideo
Department of Gastroenterological Surgery, Graduate School of Medical Sciences, Kumamoto University, Kumamoto, Japan.
Ann Surg Oncol. 2014 Jan;21(1):343-50. doi: 10.1245/s10434-013-3325-7. Epub 2013 Oct 24.
The ToGA trial demonstrated the significant efficacy of trastuzumab in addition to chemotherapy in patients with HER2-positive gastric cancer (GC). Although trastuzumab has become a key drug in breast cancer treatment, resistance to trastuzumab is a major problem in clinical practice. The aim of the current study was to identify the micro-RNA (miR)/gene pathway regulating the sensitivity of HER2-positive GC cells to trastuzumab.
Correlations between the expression levels of miR-21, PTEN, and p-AKT were analyzed by real-time PCR and Western blot test in HER2-positive GC cell lines. The effects of overexpression or suppression of miR-21 on the sensitivity of GC cells to trastuzumab were also analyzed in vitro.
Overexpression of miR-21 down-regulated PTEN expression, increased AKT phosphorylation, and did not affect HER2 expression. Inversely, suppression of miR-21 increased PTEN expression and down-regulated AKT phosphorylation, but still did not affect HER2 expression. Overexpression of miR-21 decreased the sensitivity of GC cells to trastuzumab, while suppression of miR-21 expression restored the resistance of GC cells to trastuzumab. Overexpression of miR-21 significantly suppressed trastuzumab-induced apoptosis.
To our knowledge, this study was the first reveal the miR-21/PTEN pathway regulated the sensitivity of HER2-positive GC cell lines to trastuzumab through modulation apoptosis. These findings suggest that this pathway may be crucial to the mechanism of resistance to trastuzumab in GC, which may lead to the development of individualized treatment in clinical practice.
ToGA试验证明，曲妥珠单抗联合化疗对人表皮生长因子受体2（HER2）阳性胃癌（GC）患者具有显著疗效。尽管曲妥珠单抗已成为乳腺癌治疗的关键药物，但临床实践中曲妥珠单抗耐药是一个主要问题。本研究的目的是确定调节HER2阳性GC细胞对曲妥珠单抗敏感性的微小RNA（miR）/基因通路。
通过实时聚合酶链反应（PCR）和蛋白质免疫印迹法检测HER2阳性GC细胞系中miR-21、第10号染色体缺失的磷酸酶及张力蛋白同源物（PTEN）和磷酸化蛋白激酶B（p-AKT）的表达水平，并分析它们之间的相关性。体外分析miR-21过表达或抑制对GC细胞对曲妥珠单抗敏感性的影响。
miR-21过表达下调PTEN表达，增加AKT磷酸化，且不影响HER2表达。相反，抑制miR-21可增加PTEN表达并下调AKT磷酸化，但仍不影响HER2表达。miR-21过表达降低了GC细胞对曲妥珠单抗的敏感性，而抑制miR-21表达可恢复GC细胞对曲妥珠单抗的耐药性。miR-21过表达显著抑制曲妥珠单抗诱导的细胞凋亡。
据我们所知，本研究首次揭示miR-21/PTEN通路通过调节细胞凋亡来调控HER2阳性GC细胞系对曲妥珠单抗的敏感性。这些发现表明，该通路可能是GC中曲妥珠单抗耐药机制的关键环节，这可能会促使临床实践中个体化治疗方案的发展。
