Department of Orthopaedic Surgery, Kobe University, Graduate School of Medicine, Kobe, Japan.
J Orthop Res. 2014 Feb;32(2):231-7. doi: 10.1002/jor.22506. Epub 2013 Oct 24.
Phosphatase and tensin homologue deleted on chromosome 10 (PTEN) was identified as an important tumor suppressor gene. PTEN functions as a negative regulator of phosphoinositol-3-kinase (PI3K)-Akt and MEK/ERK signaling. The PI3K-Akt pathway is critical for cell survival, differentiation, and matrix synthesis. Oxidative stress is considered a critical factor in the onset and progression of osteoarthritis (OA). Therefore, we investigated the function of PTEN in OA chondrocytes under oxidative stress. Chondrocytes were treated with insulin-like growth factor-1 (IGF-1) and/or tert-butyl hydroperoxide (tBHP), which causes oxidative stress. The expression levels of type2 collagen (Col2a1) and aggrecan were analyzed by real-time PCR, and phosphorylation of Akt and ERK1/2 was analyzed by Western blotting. Chondrocytes were treated with PTEN-specific small interfering RNA (siRNA), as well as IGF-1 and/or tBHP. PTEN and IGF-1 expressions in OA chondrocytes were increased. The downregulation of PTEN expression increased the expression levels of Col2a1 and aggrecan, and increased proteoglycan synthesis under oxidative stress. Oxidative stress decreased the phosphorylation of Akt and increased that of ERK1/2. The downregulation of PTEN expression increased Akt phosphorylation, but did not increase that of ERK 1/2. Our results suggest that PTEN regulates matrix synthesis via the PI3K-Akt pathway under oxidative stress.
第 10 号染色体缺失的磷酸酶和张力蛋白同源物（PTEN）被鉴定为一个重要的肿瘤抑制基因。PTEN 作为磷酸肌醇-3-激酶（PI3K）-Akt 和 MEK/ERK 信号的负调节剂发挥作用。PI3K-Akt 途径对于细胞存活、分化和基质合成至关重要。氧化应激被认为是骨关节炎（OA）发病和进展的一个关键因素。因此，我们研究了 PTEN 在 OA 软骨细胞中的功能在氧化应激下。用胰岛素样生长因子-1（IGF-1）和/或叔丁基过氧化氢（tBHP）处理软骨细胞，引起氧化应激。通过实时 PCR 分析 II 型胶原（Col2a1）和聚集蛋白聚糖的表达水平，通过 Western blot 分析 Akt 和 ERK1/2 的磷酸化。用 PTEN 特异性小干扰 RNA（siRNA）以及 IGF-1 和/或 tBHP 处理软骨细胞。OA 软骨细胞中的 PTEN 和 IGF-1 表达增加。下调 PTEN 表达可增加 Col2a1 和聚集蛋白聚糖的表达水平，并增加氧化应激下的蛋白聚糖合成。氧化应激降低了 Akt 的磷酸化，增加了 ERK1/2 的磷酸化。下调 PTEN 表达可增加 Akt 的磷酸化，但不会增加 ERK1/2 的磷酸化。我们的结果表明，PTEN 通过 PI3K-Akt 途径调节氧化应激下的基质合成。
