Department of Oral and Maxillofacial Surgery, Hyogo College of Medicine, Nishinomiya, Hyogo 663‑8501, Japan.
Mol Med Rep. 2021 Sep;24(3). doi: 10.3892/mmr.2021.12320. Epub 2021 Jul 28.
Aging cells not only cease growing, but also secrete various proteins such as inflammatory cytokines. This secretory phenomenon is known as the senescence‑associated secretory phenotype (SASP). The aim of the present study was to elucidate the effects of senescence on the differentiation of osteoclast precursors (OCPs) and corresponding SASP. RAW264.7 cells were used as OCPs and were cultured to passage (P)5, P10 and P20. Cell proliferation assays, senescence‑associated β‑galactosidase staining and telomere length quantification were subsequently performed, and it was revealed that replicative senescence was induced at P20. In addition, the level of tartrate‑resistant acid phosphatase activity in P20 cells treated with receptor activator of nuclear factor‑κB ligand was significantly lower than that in P5 and P10 cells. The SASP factors interleukin‑6, tumour necrosis factor‑α and nitric oxide were significantly increased in P20 culture supernatants compared with those in P5 and P10 supernatants. Furthermore, the number of exosomes at P20 was increased compared with that at P5 and P10, and inducible nitric oxide synthase (iNOS) was expressed in exosomes at P20, but not in exosomes at P5. In conclusion, the present study revealed that senescent RAW264.7 cells exhibit increased expression of SASP factors and release iNOS in exosomes.
衰老细胞不仅停止生长，还会分泌各种蛋白质，如炎症细胞因子。这种分泌现象被称为衰老相关分泌表型（SASP）。本研究旨在阐明衰老对破骨细胞前体细胞（OCP）分化及相应 SASP 的影响。采用 RAW264.7 细胞作为 OCP，并培养至第 5、10 和 20 代（P）。随后进行细胞增殖试验、衰老相关β-半乳糖苷酶染色和端粒长度定量分析，结果显示在 P20 诱导复制性衰老。此外，用核因子-κB 受体激活剂配体处理 P20 细胞后，抗酒石酸酸性磷酸酶活性显著低于 P5 和 P10 细胞。与 P5 和 P10 上清液相比，P20 培养上清液中白细胞介素-6、肿瘤坏死因子-α和一氧化氮等 SASP 因子显著增加。此外，与 P5 和 P10 相比，P20 的外泌体数量增加，并且 P20 的外泌体中表达诱导型一氧化氮合酶（iNOS），而 P5 的外泌体中不表达。综上所述，本研究表明衰老的 RAW264.7 细胞中 SASP 因子表达增加，并在外泌体中释放 iNOS。
