Intensive use of methotrexate (MTX) and/or dexamethasone (DEX) for treating childhood malignancies is known to cause chondrocyte apoptosis and growth plate dysfunction leading to bone growth impairments. However, mechanisms remain vague and it is unclear whether MTX and DEX combination treatment could have additive effects in the growth plate defects. In this study, significant cell apoptosis was induced in mature ATDC5 chondrocytes after treatment for 48 h with 10⁻⁵ M MTX and/or 10⁻⁶ M DEX treatment. PCR array assays with treated cells plus messenger RNA and protein expression confirmation analyses identified chemokine CXCL12 having the most prominent induction in each treatment group. Conditioned medium from treated chondrocytes stimulated migration of RAW264.7 osteoclast precursor cells and formation of osteoclasts, and these stimulating effects were inhibited by the neutralizing antibody for CXCL12. Additionally, while MTX and DEX combination treatment showed some additive effects on apoptosis induction, it did not have additive or counteractive effects on CXCL12 expression and its functions in enhancing osteoclastic recruitment and formation. In young rats treated acutely with MTX, there was increased expression of CXCL12 in the tibial growth plate, and more resorbing chondroclasts were found present at the border between the hypertrophic growth plate and metaphysis bone. Thus, the present study showed an association between induced chondrocyte apoptosis and stimulated osteoclastic migration and formation following MTX and/or DEX treatment, which could be potentially or at least partially linked molecularly by CXCL12 induction. This finding may contribute to an enhanced mechanistic understanding of bone growth impairments following MTX and/or DEX therapy.

中文翻译：

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凋亡软骨细胞衍生的 CXCL12 在甲氨蝶呤和/或地塞米松治疗后增强的软骨细胞募集中的作用

已知大量使用甲氨蝶呤 (MTX) 和/或地塞米松 (DEX) 治疗儿童恶性肿瘤会导致软骨细胞凋亡和生长板功能障碍，从而导致骨骼生长障碍。然而，机制仍然模糊，目前尚不清楚 MTX 和 DEX 联合治疗是否会对生长板缺陷产生累加效应。在这项研究中，在用 10 ^-5  M MTX 和/或 10 ^-6处理 48 小时后，成熟的 ATDC5 软骨细胞诱导了显着的细胞凋亡。 M DEX 处理。用处理过的细胞加上信使 RNA 和蛋白质表达确认分析的 PCR 阵列分析确定了趋化因子 CXCL12 在每个处理组中具有最显着的诱导作用。来自处理过的软骨细胞的条件培养基刺激了 RAW264.7 破骨细胞前体细胞的迁移和破骨细胞的形成，而这些刺激作用被 CXCL12 的中和抗体所抑制。此外，虽然 MTX 和 DEX 联合治疗对细胞凋亡诱导显示出一些累加作用，但它对 CXCL12 表达及其在增强破骨细胞募集和形成中的功能没有累加或反作用。在用 MTX 急性治疗的年轻大鼠中，胫骨生长板中 CXCL12 的表达增加，并且在肥大生长板和干骺端骨之间的边界处发现了更多的再吸收软骨细胞。因此，本研究表明 MTX 和/或 DEX 治疗后诱导的软骨细胞凋亡与刺激的破骨细胞迁移和形成之间存在关联，这可能或至少部分通过 CXCL12 诱导在分子上相关。这一发现可能有助于增强对 MTX 和/或 DEX 治疗后骨生长障碍的机制理解。