Guanghua School of Stomatology, Hospital of Stomatology, Sun Yat-sen University and Guangdong Provincial Key Laboratory of Stomatology, Guangzhou, Guangdong 510080, P.R. China.
The Affiliated High School of South China Normal University, Guangzhou, Guangdong 510630, P.R. China.
Oncol Rep. 2017 Aug;38(2):850-858. doi: 10.3892/or.2017.5749. Epub 2017 Jun 23.
E-cadherin (E-cad) is recently reported to be expressed in early stages of osteoclastogenesis, and blocking E-cad with neutralizing antibodies decreases osteoclast differentiation. Since our previous research demonstrates the loss of E-cad protein in the bone invasion by oral squamous cell carcinoma (OSCC), we hypothesize that E-cad may be utilized by monocytes to fuse and differentiate into osteoclasts. Two research models are used in the present study to explore our hypothesis. On one hand, we use OSCC cells of SCC25 to establish an animal model of bone invasion by OSCC, and investigate whether E-cad protein disappears in vivo; on the other hand, we use the indirect co-culture model of SCC25 and RAW 264.7 cells, with the treatment of transforming growth factor-β1 (TGF-β1), and observe whether the decreased E-cad protein is 'hijacked' in vitro. Results showed the animal model of OSCC with bone invasion was successfully established. Immunohistochemistry (IHC) found similar changes of E-cad protein, which was weakly stained by tumour cells. By using 5 ng/ml of TGF-β1, we confirmed the artificial epithelial-mesenchymal transition (EMT) of SCC25 cells, with changes of EMT marker expression and cell morphology. Real-time PCR showed E-cad mRNA decreased in SCC25 while increased in RAW 264.7 of the indirect cell co-culture model, and immunofluoresence (IF) observed the evident switch of E-cad staining from SCC25 to RAW 264.7. With the supplement of receptor activator of NF-κB ligand (RANKL), tartrate-resistant acid phosphatase (TRAP) and F-actin staining confirmed the increased number of osteoclasts. Taken together, our study found the switch of E-cad protein in the progression of bone invasion by OSCC. The loss of E-cad in tumour cells may be utilized by monocytes to differentiate into osteoclasts, thus further explaining the underlying mechanisms of bone invasion by OSCC, which may supply clues for future molecular biotherapies.
E-钙黏蛋白 (E-cad) 最近被报道在破骨细胞分化的早期阶段表达，用中和抗体阻断 E-cad 可减少破骨细胞分化。由于我们之前的研究表明口腔鳞状细胞癌 (OSCC) 骨侵袭中 E-cad 蛋白丢失，我们假设 E-cad 可能被单核细胞利用来融合并分化为破骨细胞。本研究采用两种研究模型来探讨我们的假设。一方面，我们使用 SCC25 口腔鳞状癌细胞建立 OSCC 骨侵袭的动物模型，并研究 E-cad 蛋白是否在体内消失；另一方面，我们使用 SCC25 和 RAW 264.7 细胞的间接共培养模型，用转化生长因子-β1 (TGF-β1) 处理，并观察体外减少的 E-cad 蛋白是否被“劫持”。结果表明，成功建立了 OSCC 伴骨侵袭的动物模型。免疫组化 (IHC) 发现肿瘤细胞 E-cad 蛋白染色变弱，E-cad 蛋白有类似的变化。用 5ng/ml 的 TGF-β1 证实了 SCC25 细胞的人工上皮间质转化 (EMT)， EMT 标志物表达和细胞形态发生变化。实时 PCR 显示间接细胞共培养模型中 SCC25 的 E-cad mRNA 减少，而 RAW 264.7 的 E-cad mRNA 增加，免疫荧光 (IF) 观察到 E-cad 染色从 SCC25 到 RAW 264.7 的明显转变。用核因子-κB 受体激活剂配体 (RANKL) 补充后，抗酒石酸酸性磷酸酶 (TRAP) 和 F-肌动蛋白染色证实破骨细胞数量增加。综上所述，本研究发现 OSCC 骨侵袭过程中 E-cad 蛋白的转换。肿瘤细胞中 E-cad 的丢失可能被单核细胞利用来分化为破骨细胞，从而进一步解释 OSCC 骨侵袭的潜在机制，为未来的分子生物治疗提供线索。
