Real Pedro Jose, Cao Yeyu, Wang Renxiao, Nikolovska-Coleska Zaneta, Sanz-Ortiz Jaime, Wang Shaomeng, Fernandez-Luna Jose Luis
Unidad de Genetica Molecular and Servicio de Oncologia Medica, Hospital Universitario Marques de Valdecilla, Servicio Cantabro de Salud, Santander, Spain.
Cancer Res. 2004 Nov 1;64(21):7947-53. doi: 10.1158/0008-5472.CAN-04-0945.
Proteins of the Bcl-2 family are key regulators of caspase activation and apoptosis. Some members of this family, notably Bcl-2 and Bcl-x(L), are overexpressed in cancer cells, which have been associated with chemoresistance. We have designed and synthesized a small molecule inhibitor of Bcl-2, named YC137, and studied its role in cancer cells. In vitro studies showed that YC137 inhibits the binding of the Bid BH3 peptide to Bcl-2, thus disrupting an interaction essential for the antiapoptotic activity of Bcl-2. This inhibitor induces apoptosis of hematopoietic progenitors overexpressing Bcl-2 but not Bcl-x(L) and breast cancer cells that express high levels of Bcl-2. On the contrary, a variety of normal primary cells, including CD34(+) progenitors, myoblasts, and peripheral blood mononuclear cells, do not respond to the inhibitor. A breast cancer cell line resistant to YC137 was generated. Analysis of resistant cells revealed a reduced expression of Bcl-2, which correlated with low activation of signal transducer and activator of transcription-3 (Stat3) and reduced expression of the human epidermal growth factor receptor-2 (HER2). Of note, YC137-resistant cells were more sensitive to apoptosis induced by chemotherapy. Because HER2 has not been linked previously to the Stat3-Bcl-2 transcriptional pathway, we additionally confirmed that specific blockade of HER2 in breast cancer cells resulted in down-regulation of Stat3 activity and reduced levels of Bcl-2. Consistently, HER2 blockade led to YC137 resistance. These data provide evidence for the selective killing of tumor cells by YC137 and represent the first example of in vitro selection of cancer cells refractory to a Bcl-2 inhibitor.
Bcl-2家族蛋白是半胱天冬酶激活和细胞凋亡的关键调节因子。该家族的一些成员，特别是Bcl-2和Bcl-x(L)，在癌细胞中过表达，这与化疗耐药性有关。我们设计并合成了一种名为YC137的Bcl-2小分子抑制剂，并研究了其在癌细胞中的作用。体外研究表明，YC137抑制Bid BH3肽与Bcl-2的结合，从而破坏了Bcl-2抗凋亡活性所必需的相互作用。这种抑制剂可诱导过表达Bcl-2而非Bcl-x(L)的造血祖细胞以及高表达Bcl-2的乳腺癌细胞凋亡。相反，包括CD34(+)祖细胞、成肌细胞和外周血单核细胞在内的多种正常原代细胞对该抑制剂无反应。我们构建了对YC137耐药的乳腺癌细胞系。对耐药细胞的分析显示Bcl-2表达降低，这与信号转导和转录激活因子3（Stat3）的低激活以及人表皮生长因子受体2（HER2）的表达降低相关。值得注意的是，对YC137耐药的细胞对化疗诱导的凋亡更敏感。由于HER2此前未与Stat3-Bcl-2转录途径相关联，我们还进一步证实，在乳腺癌细胞中特异性阻断HER2会导致Stat3活性下调以及Bcl-2水平降低。一致地，HER2阻断导致对YC137耐药。这些数据为YC137选择性杀伤肿瘤细胞提供了证据，并且代表了体外筛选对Bcl-2抑制剂难治的癌细胞的首个实例。
