Liao Tongquan, Chen Wugui, Sun Jing, Zhang Ying, Hu Xu, Yang Sizhen, Qiu Hao, Li Songtao, Chu Tongwei
Cell Physiol Biochem. 2018;50(3):1084-1099. doi: 10.1159/000494533. Epub 2018 Oct 24.
BACKGROUND/AIMS: Non-small cell lung carcinoma (NSCLC) metastasis to bone leads to skeletal-related events and a poor quality of life. Unravelling the mechanism of metastasis is crucial for improving survival. Previous work has implicated the role of CXCR4 in bone metastasis; however, the underlying mechanisms are unknown.
The human bone metastasis tissue samples were obtained from lung cancer patients during surgery with consents. The patients were followed up and the overall survival curve was analysed. The expression of CXCR4, VCAM1, and ADAM17 was measured with real-time PCR, western blot and immunochemistry staining in human tissue or NSCLC cell lines. The effects of CXCR4, soluble VCAM1 and ADAM17 on NSCLC proliferation, migration and invasion were measured with CCK-8, monolayer scratch assay and transwell chamber, respectively. The amount of soluble VCAM1 in the conditioned medium was detected with ELISA. Tartrate-resistant acid phosphatasethe (TRAP) staining was performed to stain the multinucleated cells regarded as osteoclasts.
In this study, CXCR4 was found to be highly expressed in bone destruction area of metastatic NSCLC samples and related to poor survival in NSCLC patients with bone metastasis. CXCR4 potentiated NSCLC with enhanced proliferation and invasion abilities, while CXCR4 knockdown significantly suppressed the growth and invasion. Furthermore, CXCR4 promoted lung cancer-induced osteoclast differentiation with increased osteoclast formation. We also found that soluble VCAM1 (sVCAM1) secreted in NSCLC contributed to the osteoclastogenesis induced by CXCR4. The overexpression of CXCR4 increased sVCAM1, and the sVCAM1 secreted from CXCR4-overexpressing NSCLC cells recruited and arrested additional osteoclast progenitors to promote osteoclastogenesis. ADAM17 was confirmed to act as a downstream mediator of CXCR4. The chemical inhibition of ADAM17 with TAPI-2 decreased sVCAM1 secretion and the number of TRAP+ osteoclasts.
Taken together, these results indicated that CXCR4 potentiated NSCLC and promoted osteoclastogenesis through sVCAM1, which was cleaved by ADAM17. These data support the pivotal role of the cross talk between CXCR4 and ADAM17-VCAM1 in NSCLC-induced bone metastasis.
背景/目的：非小细胞肺癌（NSCLC）转移至骨骼会导致骨相关事件及生活质量下降。阐明转移机制对于提高生存率至关重要。先前的研究表明CXCR4在骨转移中发挥作用；然而，其潜在机制尚不清楚。
在获得患者同意的情况下，于手术期间从肺癌患者获取人骨转移组织样本。对患者进行随访并分析总生存曲线。通过实时PCR、蛋白质印迹法及免疫化学染色检测人组织或NSCLC细胞系中CXCR4、血管细胞黏附分子1（VCAM1）和A 解整合素金属蛋白酶17（ADAM17）的表达。分别采用CCK-8法、单层划痕试验及Transwell小室检测CXCR4、可溶性VCAM1和ADAM17对NSCLC增殖、迁移及侵袭的影响。用酶联免疫吸附测定法（ELISA）检测条件培养基中可溶性VCAM1的量。进行抗酒石酸酸性磷酸酶（TRAP）染色以标记被视为破骨细胞的多核细胞。
在本研究中，发现CXCR4在转移性NSCLC样本的骨破坏区域高表达，且与NSCLC骨转移患者的不良生存相关。CXCR4增强了NSCLC的增殖和侵袭能力，而敲低CXCR4则显著抑制其生长和侵袭。此外，CXCR4促进肺癌诱导的破骨细胞分化，使破骨细胞形成增加。我们还发现NSCLC分泌的可溶性VCAM1（sVCAM1）有助于CXCR4诱导的破骨细胞生成。CXCR4的过表达增加了sVCAM1，从过表达CXCR4的NSCLC细胞分泌的sVCAM1募集并留住更多破骨细胞祖细胞以促进破骨细胞生成。证实ADAM17作为CXCR4的下游介质发挥作用。用TAPI-2对ADAM17进行化学抑制可减少sVCAM1分泌及TRAP+破骨细胞的数量。
综上所述，这些结果表明CXCR4通过被ADAM17裂解的sVCAM1增强NSCLC并促进破骨细胞生成。这些数据支持CXCR4与ADAM17-VCAM1之间的相互作用在NSCLC诱导的骨转移中起关键作用。
