ErbB-2 inhibition activates Notch-1 and sensitizes breast cancer cells to a γ-secretase inhibitor
ErbB-2 inhibition activates Notch-1 and sensitizes breast cancer cells to a γ-secretase inhibitor
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DOI：
10.1038/onc.2008.149
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发表时间：
2008-08-28
期刊：
影响因子：
8
通讯作者：
Miele, L.
中科院分区：
文献类型：
--
作者：
Osipo, C.;Patel, P.;Miele, L.
乳腺肿瘤中ErbB-2过表达与生存率低相关。Notch-1及其配体Jagged-1的表达与最差的存活率相关，包括ErbB-2阳性肿瘤。曲妥珠单抗联合化疗是ErbB-2阳性乳腺癌的标准治疗。一部分肿瘤最初对曲妥珠单抗耐药，而对曲妥珠单抗的获得性耐药发生在转移性乳腺癌中，并与预后不良相关。因此，我们研究了Notch-1是否有助于曲妥珠单抗耐药。ErbB-2阳性细胞与非过表达细胞相比具有低Notch转录活性。曲妥珠单抗或双重表皮生长因子受体（EGFR）/ErbB-2酪氨酸激酶抑制剂（TKI）使SKBr 3、BT474和MCF-7/HER 2 -18细胞中的Notch活性增加2- 6倍。通过Notch抑制剂、γ-分泌酶抑制剂（GSI）或Notch-1小干扰RNA（siRNA）消除活性的增加。曲妥珠单抗减少Notch-1（TM）前体，增加活性Notch-1（IC）的量和核蓄积，并增加靶点Hey 1和Deltex 1 mRNA以及Hes 5、Hey 1、Hes 1蛋白的表达。重要的是，与曲妥珠单抗敏感的BT474细胞相比，曲妥珠单抗治疗6个月的曲妥珠单抗耐药BT474细胞表达的Notch-1、Hey 1、Deltex 1 mRNA以及Notch-1和Hes 5蛋白高出两倍。抗性细胞中Hey 1和Deltex 1 mRNA的增加被Notch-1 siRNA消除。曲妥珠单抗或TKI加GSI比单独使用任何一种药物更有效地抑制细胞增殖。通过siRNA减少Notch-1增加了曲妥珠单抗在BT474敏感细胞中的功效，并恢复了耐药细胞中的敏感性。曲妥珠单抗加GSI使敏感细胞的凋亡增加20- 30%。单独的GSI足以使曲妥珠单抗耐药的BT474细胞的凋亡增加20%，而曲妥珠单抗使其增加至30%。Notch-1 siRNA单独在敏感性BT474细胞中使细胞生长降低30%，在抗性BT474细胞中使细胞生长降低50%以上。此外，曲妥珠单抗敏感细胞和耐药细胞的生长都被曲妥珠单抗加Notch-1 siRNA组合完全抑制。更重要的是，Notch-1 siRNA或GSI使曲妥珠单抗耐药的BT474细胞对曲妥珠单抗重新敏感。这些结果表明，ErbB-2过表达抑制Notch-1活性，这可以被曲妥珠单抗或TKI逆转。这些结果表明，Notch-1可能在曲妥珠单抗耐药中发挥新的作用，通过抑制Notch-1可以预防或逆转曲妥珠单抗耐药。
ErbB-2 overexpression in breast tumors is associated with poor survival. Expression of Notch-1 and its ligand, Jagged-1, is associated with the poorest survival, including ErbB-2-positive tumors. Trastuzumab plus chemotherapy is the standard of care for ErbB-2-positive breast cancer. A proportion of tumors are initially resistant to trastuzumab and acquired resistance to trastuzumab occurs in metastatic breast cancer and is associated with poor prognosis. Thus, we investigated whether Notch-1 contributes to trastuzumab resistance. ErbB-2-positive cells have low Notch transcriptional activity compared to non-overexpressing cells. Trastuzumab or a dual epidermal growth factor receptor (EGFR)/ErbB-2 tyrosine kinase inhibitor (TKI) increased Notch activity by 2- to 6-fold in SKBr3, BT474 and MCF-7/HER2-18 cells. The increase in activity was abrogated by a Notch inhibitor, gamma-secretase inhibitor (GSI) or Notch-1 small-interfering RNA ( siRNA). Trastuzumab decreased Notch-1 (TM) precursor, increased amount and nuclear accumulation of active Notch-1(IC) and increased expression of targets, Hey1 and Deltex1 mRNAs, and Hes5, Hey1, Hes1 proteins. Importantly, trastuzumab-resistant BT474 cells treated with trastuzumab for 6 months expressed twofold higher Notch-1, twofold higher Hey1, ninefold higher Deltex1 mRNAs and threefold higher Notch-1 and Hes5 proteins, compared to trastuzumab-sensitive BT474 cells. The increase in Hey1 and Deltex1 mRNAs in resistant cells was abrogated by a Notch-1 siRNA. Cell proliferation was inhibited more effectively by trastuzumab or TKI plus a GSI than either agent alone. Decreased Notch-1 by siRNA increased efficacy of trastuzumab in BT474 sensitive cells and restored sensitivity in resistant cells. Trastuzumab plus a GSI increased apoptosis in sensitive cells by 20-30%. A GSI alone was sufficient to increase apoptosis in trastuzumab-resistant BT474 cells by 20%, which increased to 30% with trastuzumab. Notch-1 siRNA alone decreased cell growth by 30% in sensitive and more than 50% in resistant BT474 cells. Furthermore, growth of both trastuzumab sensitive and resistant cells was completely inhibited by combining trastuzumab plus Notch-1 siRNA. More importantly, Notch-1 siRNA or a GSI resensitized trastuzumab-resistant BT474 cells to trastuzumab. These results demonstrate that ErbB-2 overexpression suppresses Notch-1 activity, which can be reversed by trastuzumab or TKI. These results suggest that Notch-1 might play a novel role in resistance to trastuzumab, which could be prevented or reversed by inhibiting Notch-1.