Department of Orthopaedic Surgery, Kobe University Graduate School of Medicine, Kobe, Hyogo 650‑0017, Japan.
Int J Oncol. 2021 Nov;59(5). doi: 10.3892/ijo.2021.5277. Epub 2021 Oct 29.
Osteolytic bone metastasis leads to skeletal‑related events, resulting in a decline in the patient activities and survival; therefore, it is important to understand the mechanism underlying bone metastasis. Recent studies have suggested that microRNAs (miRNAs or miRs) are involved in osteoclast differentiation and/or osteolytic bone metastasis; however, the roles of miRNAs have not been elucidated. In the present study, the roles of miRNAs in bone destruction caused by breast cancer metastasis were investigated and . miR‑16, miR‑133a and miR‑223 were transfected into a human breast cancer cell line, MDA‑MB‑231. The expression of osteolytic factors in conditioned medium (miR‑CM) collected from the culture of transfected cells was assessed. To evaluate the effects of miRNAs on osteoclast differentiation and activities, tartrate‑resistant acid phosphatase (TRAP) staining and bone resorptive assays were performed in osteoclasts following miR‑CM treatment. To create bone metastasis models for histological and morphometric evaluation, miRNA‑transfected MDA‑MB‑231 cells were transplanted into the proximal tibia of nude mice. Expression of osteolytic factors, including receptor activator for nuclear factor‑κB ligand (RANKL), interleukin (IL)‑1β, IL‑6, parathyroid hormone‑related protein (PTHrP), and tumor necrosis factor (TNF), was increased in miR‑16‑CM, whereas it was decreased in both miR‑133a‑CM and miR‑223‑CM. TRAP staining and bone resorptive assays revealed that osteoclast function and activities were promoted by miR‑16‑CM treatment, whereas they were suppressed by miR‑133a‑CM and miR‑223‑CM. Consistent with findings, experiments revealed that the overexpression of miR‑16 increased osteoclast activities and bone destruction in MDA‑MB‑231 cells, whereas the opposite results were observed in both miR‑133a‑ and miR‑223‑transfected MDA‑MB‑231 cells. Our results indicated that miR‑16 promoted osteoclast activities and bone destruction caused by breast cancer metastasis in the bone microenvironment, whereas miR‑133a and miR‑223 suppressed them. These miRNAs could be potential biomarkers and therapeutic targets for breast cancer bone metastasis.
溶骨性骨转移导致与骨骼相关的事件，导致患者活动能力和生存能力下降；因此，了解骨转移的机制非常重要。最近的研究表明，微小 RNA（miRNA 或 miRs）参与破骨细胞分化和/或溶骨性骨转移；然而，miRNA 的作用尚未阐明。在本研究中，研究了 miRNA 在乳腺癌转移引起的骨破坏中的作用。将 miR-16、miR-133a 和 miR-223 转染到人乳腺癌细胞系 MDA-MB-231 中。评估从转染细胞培养物中收集的溶骨性因子条件培养基（miR-CM）中的表达。为了评估 miRNA 对破骨细胞分化和活性的影响，在 miR-CM 处理后，在破骨细胞中进行抗酒石酸酸性磷酸酶（TRAP）染色和骨吸收测定。为了进行组织学和形态计量学评估的骨转移模型的创建，将 miRNA 转染的 MDA-MB-231 细胞移植到裸鼠的近端胫骨中。骨溶解因子，包括核因子-κB 配体受体激活剂（RANKL）、白细胞介素（IL）-1β、IL-6、甲状旁腺激素相关蛋白（PTHrP）和肿瘤坏死因子（TNF）的表达在 miR-16-CM 中增加，而在 miR-133a-CM 和 miR-223-CM 中减少。TRAP 染色和骨吸收测定表明，miR-16-CM 处理促进破骨细胞功能和活性，而 miR-133a-CM 和 miR-223-CM 则抑制破骨细胞功能和活性。实验结果与发现一致，表明 miR-16 的过表达增加了 MDA-MB-231 细胞中的破骨细胞活性和骨破坏，而在 miR-133a 和 miR-223 转染的 MDA-MB-231 细胞中则观察到相反的结果。我们的结果表明，miR-16 促进了乳腺癌转移在骨微环境中引起的破骨细胞活性和骨破坏，而 miR-133a 和 miR-223 则抑制了它们。这些 miRNA 可能是乳腺癌骨转移的潜在生物标志物和治疗靶点。
