Purpose

CD81 is a member of the tetraspanin family of membrane proteins. Recently, it has been shown that CD81 may be involved in cancer cell proliferation and metastasis. As yet, however, there have been few reports on the expression and role of CD81 in osteosarcoma.

Methods

The expression of CD81 was investigated in human osteoblast cell line hFOB1.19 and in human osteosarcoma cell lines Saos2, MG63 and 143B. The expression of CD81 was inhibited in osteosarcoma cells using siRNA after which cell proliferation, migration and invasion were assessed. We also used Western blotting to investigate the phosphorylation status of Akt, Erk, JNK and p38, and measured the expression of MMP-2, MMP-9 and MT1-MMP. In addition, we used a CRISPR/Cas9 system to stably knock out CD81 expression in 143B cells, transplanted the cells into mice, and assessed tumor formation and lung metastasis in these mice compared to those in the control group.

Results

We found that CD81 was expressed in the human osteoblast cell line and in all osteosarcoma cell lines tested. The osteosarcoma cell line 143B exhibited a particularly high level of expression. In addition, we found that osteosarcoma cell proliferation, migration and invasion were decreased after CD81 inhibition, and that the phosphorylation of Akt and Erk was suppressed. Also, the expression levels of MMP-2, MMP-9 and MT1-MMP were found to be suppressed, with MMP-9 showing the greatest suppression. In vivo, we found that mice transplanted with CD81 knockout 143B cells exhibited significantly less tumor formation and lung metastasis than mice in the control group.

Conclusion

Based on our findings we conclude that inhibition of CD81 suppresses intracellular signaling and reduces tumorigenesis and lung metastasis in osteosarcoma cells.

中文翻译：

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四跨膜蛋白 CD81 介导人骨肉瘤的生长和转移。

目的

CD81 是膜蛋白四跨膜蛋白家族的成员。最近，已经表明 CD81 可能参与癌细胞增殖和转移。然而，迄今为止，关于 CD81 在骨肉瘤中的表达和作用的报道很少。

方法

在人成骨细胞系 hFOB1.19 和人骨肉瘤细胞系 Saos2、MG63 和 143B 中研究了 CD81 的表达。使用siRNA抑制骨肉瘤细胞中CD81的表达，然后评估细胞增殖、迁移和侵袭。我们还使用蛋白质印迹研究 Akt、Erk、JNK 和 p38 的磷酸化状态，并测量 MMP-2、MMP-9 和 MT1-MMP 的表达。此外，我们使用 CRISPR/Cas9 系统稳定敲除 143B 细胞中的 CD81 表达，将细胞移植到小鼠体内，并与对照组相比评估了这些小鼠的肿瘤形成和肺转移。

结果

我们发现 CD81 在人成骨细胞系和所有测试的骨肉瘤细胞系中表达。骨肉瘤细胞系143B表现出特别高的表达水平。此外，我们发现CD81抑制后骨肉瘤细胞增殖、迁移和侵袭减少，Akt和Erk的磷酸化受到抑制。此外，发现 MMP-2、MMP-9 和 MT1-MMP 的表达水平受到抑制，其中 MMP-9 显示出最大的抑制。在体内，我们发现移植了 CD81 敲除 143B 细胞的小鼠的肿瘤形成和肺转移明显少于对照组小鼠。

结论

基于我们的研究结果，我们得出结论，CD81 的抑制会抑制细胞内信号传导并减少骨肉瘤细胞的肿瘤发生和肺转移。