Department of Craniofacial Biology, Center for Oral Health Research Medical University of South Carolina, Charleston, SC, USA.
Oral Oncol. 2013 Feb;49(2):119-28. doi: 10.1016/j.oraloncology.2012.08.004. Epub 2012 Sep 16.
Local invasion of bone is a frequent complication of oral squamous cell carcinoma (OSCC). Development of these osteolytic lesions is mediated by osteoclasts. Receptor activation of NF-κB ligand (RANKL) signaling, counteracted by osteoprotegerin (OPG), regulates osteoclastogenesis. Previous studies in rodent models have demonstrated that inhibition of RANKL decreases tumor growth and lesions within bone. However, the contributory role of OSCC cells to this disease process has yet to be defined.
RANKL expression was assessed in a panel of OSCC cell lines by qPCR, flow cytometry, and ELISA. Induction of osteoclastogenesis was assessed by co-culture with macrophages or with OSCC-derived conditioned medium. In an animal model of bone invasion, nude mice were injected intratibially with UMSCC-11B cells expressing a RANKL luciferase promoter to detect tumor-derived RANKL activity. Osteolytic lesions were analyzed by X-ray, micro-CT, and histological methods. RANKL expression was assessed in human OSCC tissues by immunohistochemistry.
We demonstrated that OSCCs express varied levels of all RANKL isoforms, both membrane-bound and soluble RANKL. Both co-culture and treatment with OSCC-conditioned media induced osteoclastogenesis. In mice, we demonstrated human RANKL promoter activity during bone invasion. Over the course of the experiment, animals suffered osteolytic lesions as RANKL-driven luciferase expression increased with time. After 8weeks, human-derived RANKL was detected in areas of bone resorption by immunohistochemistry. Similar epithelial RANKL expression was detected in human OSCC tissues.
These data demonstrate the ability of OSCCs to produce RANKL, directly altering the tumor microenvironment to increase osteoclastogenesis and mediate local bone invasion.
口腔鳞状细胞癌（OSCC）常发生骨局部侵袭。这些溶骨性病变的发展是由破骨细胞介导的。核因子-κB 配体（RANKL）信号的受体激活，被骨保护素（OPG）拮抗，调节破骨细胞生成。先前在啮齿动物模型中的研究表明，抑制 RANKL 可减少肿瘤生长和骨内病变。然而，OSCC 细胞在这一疾病过程中的贡献作用尚未确定。
通过 qPCR、流式细胞术和 ELISA 评估 OSCC 细胞系中 RANKL 的表达。通过与巨噬细胞共培养或与 OSCC 衍生的条件培养基共培养来评估破骨细胞生成的诱导。在骨侵袭的动物模型中，将表达 RANKL 荧光素酶启动子的 UMSCC-11B 细胞经胫骨内注射入裸鼠，以检测肿瘤来源的 RANKL 活性。通过 X 射线、微 CT 和组织学方法分析溶骨性病变。通过免疫组织化学评估人 OSCC 组织中的 RANKL 表达。
我们证明 OSCC 表达各种 RANKL 同工型，包括膜结合和可溶性 RANKL。共培养和 OSCC 条件培养基处理均诱导破骨细胞生成。在小鼠中，我们在骨侵袭过程中证明了人 RANKL 启动子活性。在实验过程中，随着 RANKL 驱动的荧光素酶表达随时间增加，动物遭受溶骨性病变。8 周后，通过免疫组织化学在骨吸收区域检测到人源性 RANKL。在人 OSCC 组织中也检测到类似的上皮 RANKL 表达。
这些数据表明 OSCC 具有产生 RANKL 的能力，直接改变肿瘤微环境以增加破骨细胞生成并介导局部骨侵袭。
