Wang Ning, Reeves Kimberley J, Brown Hannah K, Fowles Anne C M, Docherty Freyja E, Ottewell Penelope D, Croucher Peter I, Holen Ingunn, Eaton Colby L
The Mellanby Centre for Bone Research, Department of Human Metabolism, Medical School, University of Sheffield, Beech Hill Road, Sheffield, S10 2RX, UK.
Break Through Breast Cancer Research Unit, Paterson Institute for Cancer Research Manchester, Manchester, UK.
J Exp Clin Cancer Res. 2015 Oct 20;34:124. doi: 10.1186/s13046-015-0240-8.
While both preclinical and clinical studies suggest that the frequency of growing skeletal metastases is elevated in individuals with higher bone turnover, it is unclear whether this is a result of increased numbers of tumour cells arriving in active sites or of higher numbers of tumour cells being induced to divide by the bone micro-environment. Here we have investigated how the differences in bone turnover affect seeding of tumour cells and/or development of overt osteolytic bone metastasis using in vivo models of hormone-independent breast and prostate cancer.
Cohorts of 6 (young) and 16 (mature)-week old BALB/c nude mice were culled 1, 7 and 21 days after received intracardiac injection of luciferase expressing human prostate (PC3) or breast cancer (MDA-MB-231) cell lines labelled with a fluorescent cell membrane dye (Vybrant DiD). The presence of growing bone metastases was determined by bioluminescence using an in vivo imaging system (IVIS) and followed by anatomical confirmation of tumour metastatic sites post mortem, while the presence of individual fluorescently labelled tumour cells was evaluated using two-photon microscopy ex vivo. The bone remodelling activities were compared between young and mature naïve mice (both male and female) using micro-CT analysis, ELISA and bone histomorphometry.
Both prostate and breast cancer cells generated higher numbers of overt skeletal lesions in young mice (80%) than in mature mice (20%). Although mature mice presented with fewer overt bone metastases, the number of tumour cells arriving/colonizing in the tibias was comparable between young and mature animals. Young naïve mice had lower bone volume but higher bone formation and resorption activities compared to mature animals.
Our studies suggest that higher frequencies of growing osteolytic skeletal metastases in these models are linked to increased bone turnover and not to the initial number of tumour cells entering the bone microenvironment.
虽然临床前和临床研究均表明，骨转换率较高的个体中骨骼转移瘤生长的频率有所升高，但尚不清楚这是由于到达活跃部位的肿瘤细胞数量增加，还是由于骨微环境诱导更多肿瘤细胞分裂所致。在此，我们使用激素非依赖性乳腺癌和前列腺癌的体内模型，研究了骨转换差异如何影响肿瘤细胞的播种和/或明显溶骨性骨转移的发展。
对6周龄（年轻）和16周龄（成熟）的BALB/c裸鼠队列，在经心内注射用荧光细胞膜染料（Vybrant DiD）标记的表达荧光素酶的人前列腺癌（PC3）或乳腺癌（MDA-MB-231）细胞系后1、7和21天进行安乐死。使用体内成像系统（IVIS）通过生物发光确定骨转移瘤的生长情况，随后在死后对肿瘤转移部位进行解剖确认，同时使用双光子显微镜离体评估单个荧光标记肿瘤细胞的存在情况。使用显微CT分析、ELISA和骨组织形态计量学比较年轻和成熟的未处理小鼠（雄性和雌性）之间的骨重塑活动。
前列腺癌细胞和乳腺癌细胞在年轻小鼠（约80%）中产生的明显骨骼病变数量均高于成熟小鼠（约20%）。虽然成熟小鼠的明显骨转移较少，但年轻和成熟动物胫骨中到达/定植的肿瘤细胞数量相当。与成熟动物相比，年轻的未处理小鼠骨体积较低，但骨形成和吸收活动较高。
我们的研究表明，在这些模型中，溶骨性骨骼转移瘤生长频率较高与骨转换增加有关，而与进入骨微环境的肿瘤细胞初始数量无关。
