BACKGROUND Late-stage breast cancer preferentially metastasises to bone; despite advances in targeted therapies, this condition remains incurable. The lack of clinically relevant models for studying breast cancer metastasis to a human bone microenvironment has stunted the development of effective treatments for this condition. To address this problem, we have developed humanised mouse models in which breast cancer patient-derived xenografts (PDXs) metastasise to human bone implants with low variability and high frequency. METHODS To model the human bone environment, bone discs from femoral heads of patients undergoing hip replacement surgery were implanted subcutaneously into NOD/SCID mice. For metastasis studies, 7 patient-derived xenograft tumours (PDX: BB3RC32, ER+ PR+ HER2-; BB2RC08, ER+ PR+ ER2-; BB6RC37, ER- PR- HER2- and BB6RC39, ER+ PR+ HER2+), MDA-MB-231-luc2, T47D-luc2 or MCF7-Luc2 cells were injected into the 4th mammary ducts and metastases monitored by luciferase imaging and confirmed on histological sections. Bone integrity, viability and vascularisation were assessed by uCT, calcein uptake and histomorphometry. Expression profiling of genes/proteins during different stages of metastasis were assessed by whole genome Affymetrix array, real-time PCR and immunohistochemistry. Importance of IL-1 was confirmed following anakinra treatment. RESULTS Implantation of femoral bone provided a metabolically active, human-specific site for tumour cells to metastasise to. After 4 weeks, bone implants were re-vascularised and demonstrated active bone remodelling (as evidenced by the presence of osteoclasts, osteoblasts and calcein uptake). Restricting bone implants to the use of subchondral bone and introduction of cancer cells via intraductal injection maximised metastasis to human bone implants. MDA-MB-231 cells specifically metastasised to human bone (70% metastases) whereas T47D, MCF7, BB3RC32, BB2RC08, and BB6RC37 cells metastasised to both human bone and mouse bones. Importantly, human bone was the preferred metastatic site especially from ER+ PDX (100% metastasis human bone compared with 20-75% to mouse bone), whereas ER-ve PDX developed metastases in 20% of human and 20% of mouse bone. Breast cancer cells underwent a series of molecular changes as they progressed from primary tumours to bone metastasis including altered expression of IL-1B, IL-1R1, S100A4, CTSK, SPP1 and RANK. Inhibiting IL-1B signalling significantly reduced bone metastasis. CONCLUSIONS Our reliable and clinically relevant humanised mouse models provide significant advancements in modelling of breast cancer bone metastasis.

中文翻译：

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使用人骨盘和乳腺癌患者源性异种移植物开发临床相关的体内转移模型。

背景技术晚期乳腺癌优先转移至骨；因此，转移至骨骼的可能性更高。尽管靶向疗法取得了进展，但这种情况仍然无法治愈。缺乏研究乳腺癌转移至人骨微环境的临床相关模型，阻碍了针对这种疾病的有效治疗方法的开发。为了解决这个问题，我们开发了人性化的小鼠模型，其中乳腺癌患者源性异种移植物（PDXs）以低变异性和高频率转移到人骨植入物中。方法为模拟人体骨骼环境，将接受髋关节置换手术的患者股骨头的骨盘皮下植入NOD / SCID小鼠。对于转移研究，研究了7种患者来源的异种移植肿瘤（PDX：BB3RC32，ER + PR + HER2-； BB2RC08，ER + PR + ER2-； BB6RC37，ER-PR-HER2-和BB6RC39，ER + PR + HER2 +），MDA-MB-231-luc2，T47D-luc2或MCF7-Luc2细胞被注入第4乳腺导管，并通过荧光素酶成像监测转移灶并在组织学切片上确认。通过uCT，钙黄绿素摄取和组织形态学评估骨完整性，生存力和血管形成。通过全基因组Affymetrix阵列，实时PCR和免疫组织化学评估转移不同阶段的基因/蛋白质的表达谱。anakinra治疗后证实了IL-1的重要性。结果股骨植入为肿瘤细胞转移提供了一个新陈代谢的，人类特异性的位点。4周后，将骨植入物重新血管化并显示出主动的骨重塑（如破骨细胞，成骨细胞和钙黄绿素摄取的存在所证明）。将骨植入物限制为软骨下骨的使用，并通过导管内注射引入癌细胞，可以最大程度地转移到人骨植入物。MDA-MB-231细胞特异性转移至人骨（70％转移），而T47D，MCF7，BB3RC32，BB2RC08和BB6RC37细胞转移至人骨和小鼠骨骼。重要的是，人骨是首选的转移部位，尤其是从ER + PDX（100％转移人骨，而到小鼠骨骼的转移为20-75％），而ER-ve PDX在20％人和20％小鼠骨骼中发生转移。乳腺癌细胞从原发肿瘤发展到骨转移时发生了一系列分子变化，包括IL-1B，IL-1R1，S100A4，CTSK，SPP1和RANK表达的改变。抑制IL-1B信号传导可显着降低骨转移。