Boudot Cédric, Hénaut Lucie, Thiem Ursula, Geraci Sandra, Galante Mariangela, Saldanha Paulo, Saidak Zuzana, Six Isabelle, Clézardin Philippe, Kamel Said, Mentaverri Romuald
Inserm U1088, Centre Universitaire de Recherche en Santé, Université de Picardie Jules Verne, Amiens, France.
Inserm UMR 1033, LYOS, Lyon, France.
Oncotarget. 2017 Apr 10;8(34):56460-56472. doi: 10.18632/oncotarget.16999. eCollection 2017 Aug 22.
Osteolytic bone metastases are observed in advanced cases of breast cancer. data suggest that the activity of the calcium-sensing receptor (CaSR) expressed by metastatic cells could potentiate their osteolytic potential. This study aimed to demonstrate the involvement of the CaSR in breast cancer cells osteolytic potential and to identify potential targets linked to CaSR activity.
MDA-MB-231 stably transfected with plasmids containing either a full-length wild-type CaSR (CaSR-WT), or a functionally inactive dominant negative mutant (CaSR-DN) or an empty vector (EV) were intratibially injected into Balb/c-Nude mice. X-ray analysis performed 19 days after injection showed a dramatic increase of osteolytic lesions in mice injected with CaSR-WT-transfected cells as compared to mice injected with EV- or CaSR-DN-transfected cells. This was associated with decreased BV/TV ratio and increased tumor burden. Epiregulin, an EGF-like ligand, was identified by a DNA microarray as a possible candidate involved in CaSR-mediated osteolysis. Indeed, , CaSR overexpression increased both epiregulin expression and secretion as compared to EV- or CaSR-DN-transfected cells. Increased epiregulin expression was also detected in osteolytic bone lesions from mice injected with CaSR-WT-transfected MDA-MB-231. , exposure of osteoblastic cells (HOB and SaOS2) to exogenous epiregulin significantly decreased OPG mRNA expression. Exposure of osteoblastic cells to conditioned media prepared from CaSR-WT-transfected cells also decreased OPG expression. This effect was partially blocked after addition of an anti-epiregulin antibody.
Overexpression of a functional CaSR in metastatic breast cancer cells dramatically amplifies their osteolytic potential through epiregulin-mediated OPG downregulation.
在乳腺癌晚期病例中可观察到溶骨性骨转移。数据表明，转移细胞表达的钙敏感受体（CaSR）的活性可能增强其溶骨潜能。本研究旨在证明CaSR参与乳腺癌细胞的溶骨潜能，并确定与CaSR活性相关的潜在靶点。
将稳定转染含全长野生型CaSR（CaSR-WT）、功能失活的显性负性突变体（CaSR-DN）或空载体（EV）质粒的MDA-MB-231细胞经胫骨注射到Balb/c-裸鼠体内。注射后19天进行的X射线分析显示，与注射EV或CaSR-DN转染细胞的小鼠相比，注射CaSR-WT转染细胞的小鼠溶骨病变显著增加。这与骨体积/组织体积（BV/TV）比值降低和肿瘤负荷增加有关。通过DNA微阵列鉴定出表皮调节素（一种表皮生长因子样配体）是参与CaSR介导的骨溶解的可能候选物。事实上，与EV或CaSR-DN转染细胞相比，CaSR过表达增加了表皮调节素的表达和分泌。在注射CaSR-WT转染的MDA-MB-231的小鼠的溶骨性骨病变中也检测到表皮调节素表达增加。此外，成骨细胞（HOB和SaOS2）暴露于外源性表皮调节素会显著降低骨保护素（OPG）mRNA表达。成骨细胞暴露于由CaSR-WT转染细胞制备的条件培养基中也会降低OPG表达。添加抗表皮调节素抗体后，这种作用部分被阻断。
转移性乳腺癌细胞中功能性CaSR的过表达通过表皮调节素介导的OPG下调显著增强其溶骨潜能。
