Kapeleris Joanna, Zou Hong, Qi Yan, Gu Yushu, Li Jingyun, Schoning Jennifer, Monteiro Michael J, Gu Wenyi
Australian Institute for Bioengineering and Nanotechnology, University of Queensland, Brisbane, QLD, Australia.
Department of Pathology, Key Laboratory for Xinjiang Endemic and Ethnic Diseases, Shihezi University School of Medicine, Shihezi University, Xinjiang, China.
Clin Exp Pharmacol Physiol. 2020 May;47(5):838-847. doi: 10.1111/1440-1681.13247. Epub 2020 Jan 23.
The ability of cancer cells to form clusters is a characteristic feature in the development of metastatic tumours with drug resistance. Several studies demonstrated that clusters of circulating tumour cells (CTCs) have a greater metastatic potential to establish new tumours at secondary sites than single CTCs. However, the mechanism of cluster formation is not well understood. In this study, we investigated whether cancer stemness would contribute to cluster formation. We used a tumour sphere culture method to enrich cancer stem cells (CSCs) from colon cancer cells and found that during the second generation of sphere culture, clusters (between 3 and 5 cells) formed within the first 24 hours, whereas the rest remained as single cells. The clusters were analysed for stemness and metastatic potential, including gene expressions for cancer stemness (CD133 and Lgr5), epithelial-mesenchymal transition (E-cadherin and TGF-β 1-3) and hypoxia-induced factors (HIF-1α and HIF-2α). The results showed that the clusters expressed higher levels of these genes and colon CSC surface markers (including CD24, CD44 and CD133) than the single cells. Among these markers, CD24 seemed the major contributor linking the cells into the clusters. These clusters also showed a stronger ability to both form colonies and migrate. Our data collectively suggest that colon cancer stemness contributes to cluster formation and that clustered cells exhibit a great metastatic potential. Our study thus provides a method to study the CTC clusters and derive insight into oncogenesis and metastasis.
癌细胞形成聚集体的能力是具有耐药性的转移性肿瘤发展过程中的一个特征性表现。多项研究表明，循环肿瘤细胞（CTC）聚集体在继发部位形成新肿瘤的转移潜力比单个CTC更大。然而，聚集体形成的机制尚不清楚。在本研究中，我们调查了癌症干性是否有助于聚集体的形成。我们采用肿瘤球培养方法从结肠癌细胞中富集癌症干细胞（CSC），发现在第二代球培养过程中，聚集体（3至5个细胞之间）在前24小时内形成，而其余细胞仍为单个细胞。对这些聚集体进行干性和转移潜力分析，包括癌症干性（CD133和Lgr5）、上皮-间质转化（E-钙黏蛋白和TGF-β 1-3）以及缺氧诱导因子（HIF-1α和HIF-2α）的基因表达。结果显示，与单个细胞相比，聚集体中这些基因以及结肠CSC表面标志物（包括CD24、CD44和CD133）的表达水平更高。在这些标志物中，CD24似乎是将细胞连接成聚集体的主要因素。这些聚集体还表现出更强的形成集落和迁移的能力。我们的数据共同表明，结肠癌干性有助于聚集体的形成，并且聚集体细胞具有很大的转移潜力。因此，我们的研究提供了一种研究CTC聚集体并深入了解肿瘤发生和转移的方法。
