Breast and prostate cancer are among the most common malignancies worldwide. After treatment of the primary tumor, distant metastases often occur after a long disease-free interval. Bone is a major site for breast and prostate cancer metastasis and approximately 70% of patients with advanced disese suffer from osteolytic or osteoblastic bone metastases, a stage at which the disease is incurable. In bone, the disseminated tumor cells (DTCs) can become quiescent or “dormant”, a state where they are alive but not actively dividing. Alternatively, the cancer cells can proliferate, disturb the bone homeostasis, and form metastatic lesions. The fate of cancer cells is largely dependent on the bone microenvironment, particularly the bone forming osteoblasts and bone resorbing osteoclasts. Osteoblasts originate from mesenchymal precursors through a tightly regulated cascade. The main function of osteoblasts is to synthesize bone matrix, coordinate mineralization and maintain bone remodeling by regulating osteoclast activity and bone resorption. In metastatic bone environment, osteoblasts can create a niche within the bone where DTCs cells become dormant and induce quiescence in cancer cells keeping them in a non-proliferative state. Osteoblasts also contribute to metastatic outgrowth and actively promote tumor growth in bone. In this article, we review the recent literature on the role of osteoblasts in cancer cell dormancy and bone metastasis and describe the underlying mechanisms by which osteoblasts regulate cancer cell fate in bone. In addition, we discuss the possibility of targeting osteoblasts to treat osteolytic bone metastases.

中文翻译：

---

成骨细胞调控肿瘤细胞休眠和骨转移

乳腺癌和前列腺癌是全世界最常见的恶性肿瘤之一。原发肿瘤治疗后，在较长的无病间隔后常常会发生远处转移。骨是乳腺癌和前列腺癌转移的主要部位，大约70%的晚期疾病患者患有溶骨性或成骨性骨转移，在这个阶段该疾病是无法治愈的。在骨骼中，播散性肿瘤细胞 (DTC) 可能会变得静止或“休眠”，即它们还活着但不活跃分裂的状态。或者，癌细胞可以增殖，扰乱骨稳态，并形成转移性病变。癌细胞的命运很大程度上取决于骨微环境，特别是骨形成成骨细胞和骨吸收破骨细胞。成骨细胞通过严格调控的级联起源于间充质前体。成骨细胞的主要功能是通过调节破骨细胞活性和骨吸收来合成骨基质、协调矿化并维持骨重塑。在转移性骨环境中，成骨细胞可以在骨内创建一个生态位，DTC 细胞在其中休眠并诱导癌细胞静止，使其保持在非增殖状态。成骨细胞还有助于转移性生长并积极促进骨中肿瘤的生长。在本文中，我们回顾了有关成骨细胞在癌细胞休眠和骨转移中作用的最新文献，并描述了成骨细胞调节骨中癌细胞命运的潜在机制。此外，我们还讨论了靶向成骨细胞治疗溶骨性骨转移的可能性。