Gao Xin, Mao Yun-Hua, Xiao Chutian, Li Ke, Liu Wei, Li Liao-Yuan, Pang Jun
Department of Urology, The Third Affiliated Hospital of Sun Yat-sen University, Guangzhou, P.R. China.
Guangdong Key Laboratory of Liver Disease Research, The Third Affiliated Hospital of Sun Yat-sen University, Guangzhou, P.R. China.
Prostate. 2018 Jun;78(9):682-690. doi: 10.1002/pros.23512. Epub 2018 Mar 30.
Metastasis is the major cause of cancer-specific death in patients with prostate cancer (PCa). We previously reported that collapsing response mediator protein-4 (CRMP4) is a PCa metastasis-suppressor gene and the hypermethylation in CRMP4 promoter is responsible for the transcription repression in metastatic PCa. However, the underlying mechanisms remain unknown. In this study, we aimed to investigate the role of calpain-2 in CRMP4 promoter hypermethylation and its functional modulation in PCa metastasis.
Calpain-2 expression in PCa tissues (n = 87) and its specific mechanisms of functional modulation in CRMP4 expression via limited enzymatic cleavage was investigated. We then focused on the cooperative crosstalk of calpain-2 and NF-κB RelA/p65 in CRMP4 promoter methylation for the initiation of PCa metastasis. Statistical differences between groups were determined using a two-tailed Student's t-test. P < 0.05 indicated statistically significant.
Calpain-2 was differentially upregulated in metastatic PCa compared with localized PCa. Moreover, calpain-2 cleaved CRMP4 into the N-terminally fragment which promoted migration and invasion in PCa cells via nuclear translocation and activation of E2F1-mediated DNA methyltransferase 1 (DNMT1) expression. NF-κB RelA/p65 recruited DNMT1 to bind to and methylate CRMP4 promoter in which Serine276 phosphorylation of p65 was essential. Furthermore, CRMP4 exhibited anti-metastatic function via inhibiting the expression of VEGFC through Semaphorin3B-Neuropilin2 signaling.
Calpain-2 may contribute to the promoter methylation of CRMP4 to repress its transcription, leading to the metastasis of PCa via enhancing VEGFC expression.
转移是前列腺癌（PCa）患者癌症特异性死亡的主要原因。我们之前报道过，塌陷反应中介蛋白4（CRMP4）是一种PCa转移抑制基因，CRMP4启动子的高甲基化是转移性PCa转录抑制的原因。然而，其潜在机制仍不清楚。在本研究中，我们旨在研究钙蛋白酶-2在CRMP4启动子高甲基化中的作用及其在PCa转移中的功能调节。
研究了钙蛋白酶-2在PCa组织（n = 87）中的表达及其通过有限酶切对CRMP4表达进行功能调节的具体机制。然后，我们重点研究了钙蛋白酶-2与NF-κB RelA/p65在CRMP4启动子甲基化中的协同串扰，以启动PCa转移。使用双尾学生t检验确定组间的统计学差异。P < 0.05表示具有统计学意义。
与局限性PCa相比，转移性PCa中钙蛋白酶-2差异上调。此外，钙蛋白酶-2将CRMP4切割成N端片段，该片段通过核转位和激活E2F1介导的DNA甲基转移酶1（DNMT1）表达促进PCa细胞的迁移和侵袭。NF-κB RelA/p65招募DNMT1结合并甲基化CRMP4启动子，其中p65的丝氨酸276磷酸化至关重要。此外，CRMP4通过Semaphorin3B-神经纤毛蛋白2信号通路抑制VEGFC的表达，从而发挥抗转移功能。
钙蛋白酶-2可能有助于CRMP4的启动子甲基化以抑制其转录，通过增强VEGFC表达导致PCa转移。
