Guangdong Provincial Key Laboratory of Malignant Tumor Epigenetics and Gene Regulation, Medical Research Center, Sun Yat-Sen Memorial Hospital, Sun Yat-Sen University, Guangzhou, China.
Division of Life Science, Applied Genomics Centre and Centre for Statistical Science, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China.
Theranostics. 2020 Aug 8;10(22):9984-10000. doi: 10.7150/thno.47044. eCollection 2020.
Neoadjuvant chemotherapy has become the standard treatment of locally advanced breast cancer. Antimicrotubule drugs and DNA-damaging drugs are the most popular medicines used for neoadjuvant chemotherapy. However, we are unable to predict which chemotherapeutic drug will benefit to an individual patient. PARK2 as a tumor suppressor in breast cancer has been reported. While the role of PARK2 in chemotherapy response remains unknown. In this study, we explore the impact of PARK2 on chemosensitivity in breast cancer. PARK2 expression in breast cancer patients with different neoadjuvant chemotherapeutic regimens was studied using immunohistochemistry. Data was correlated to disease-free survival (DFS), overall survival and pathologic complete response (pCR). The functional roles of PARK2 were demonstrated by a series of and experiments. Including mass spectrometry, Co-immunoprecipitation, isolation of subcellular fractionation, fluorescence microscopy, ubiquitination assay and luciferase analyses. Highly expressed PARK2 predicted better response to antimicrotubule drugs-containing regimen associated with higher rate of pathologic complete response (pCR). In contrast, PARK2 expression did not predict response to the DNA-damaging drugs regimen. Following antimicrotubule drugs treatment, levels of PARK2 was upregulated due to the repression of STAT3-mediated transcriptional inhibition of PARK2. Moreover, overexpression of PARK2 specifically rendered cells more sensitive to antimicrotubule drugs, but not to DNA-damaging drugs. Depletion of PARK2 enhanced resistance to antimicrotubule drugs. Mechanistically, PARK2 markedly activated the mitochondrial pathway of apoptosis after exposure to antimicrotubule drugs. This occurred through downregulating the antiapoptotic protein, phospho-BCL-2. BCL-2 phosphorylation can be specifically induced by antimicrotubule drugs, whereas DNA-damaging drugs do not. Notably, PARK2 interacted with phospho-BCL-2 (Ser70) and promoted ubiquitination of BCL-2 in an E3 ligase-dependent manner. Hence, PARK2 significantly enhanced the chemosensitivity of antimicrotubule drugs both , while loss-of-function PARK2 mutants did not. Our findings explained why PARK2 selectively confers chemosensitivity to antimicrotubule drugs, but not to DNA-damaging drugs. In addition, we identified PARK2 as a novel mediator of antimicrotubule drugs sensitivity, which can predict response of breast cancer patients to antimicrotubule drugs-containing regime.
新辅助化疗已成为局部晚期乳腺癌的标准治疗方法。抗微管药物和 DNA 损伤药物是新辅助化疗中最常用的药物。然而，我们无法预测哪种化疗药物对个体患者有益。已经有报道称 PARK2 是乳腺癌中的肿瘤抑制因子。然而，PARK2 在化疗反应中的作用尚不清楚。在这项研究中，我们探讨了 PARK2 对乳腺癌化疗敏感性的影响。
使用免疫组织化学研究了不同新辅助化疗方案中乳腺癌患者 PARK2 的表达。将数据与无病生存期 (DFS)、总生存期和病理完全缓解 (pCR) 相关联。通过一系列 和 实验证明了 PARK2 的功能作用。包括质谱分析、共免疫沉淀、亚细胞分离、荧光显微镜、泛素化测定和荧光素酶分析。
高表达的 PARK2 预示着对抗微管药物为主的方案有更好的反应，与更高的病理完全缓解率 (pCR) 相关。相比之下，PARK2 表达不能预测对 DNA 损伤药物方案的反应。在用抗微管药物治疗后，由于 STAT3 介导的 PARK2 转录抑制的抑制，PARK2 的水平上调。此外，PARK2 的过表达使细胞对微管药物更敏感，而对 DNA 损伤药物不敏感。PARK2 的耗竭增强了对抗微管药物的耐药性。
机制上，暴露于抗微管药物后，PARK2 明显激活了线粒体凋亡途径。这是通过下调抗凋亡蛋白磷酸化 BCL-2 来实现的。BCL-2 磷酸化可以被抗微管药物特异性诱导，而 DNA 损伤药物则不能。值得注意的是，PARK2 与磷酸化 BCL-2 (Ser70) 相互作用，并以 E3 连接酶依赖的方式促进 BCL-2 的泛素化。因此，PARK2 显著增强了抗微管药物的化疗敏感性，而功能丧失的 PARK2 突变体则没有。
我们的研究结果解释了为什么 PARK2 选择性赋予抗微管药物化疗敏感性，而不是 DNA 损伤药物。此外，我们将 PARK2 鉴定为一种新的微管药物敏感性介质，它可以预测乳腺癌患者对抗微管药物为主的方案的反应。
