Circulating Tumor Cell Clusters Are Oligoclonal Precursors of Breast Cancer Metastasis
Primary tumours spread to other parts of the body by shedding cells into the blood stream, which can seed tumours elsewhere. This process is thought to be mediated by single cells, but the authors here show that cancer cells are also found to exist in clusters when extracted from the blood, but at a very low abundance. The authors identify the factor plakoglobin which is necessary for cluster formation. Knockdown of this factor had little effect on primary tumour size, but had a striking 80% reduction in metastatic node formation in mice. This indicates that these clusters have a stronger contribution to metastases formation, than just by their abundance.
We can only speculate as to the mechanism by which these clusters gain their super-linear metastatic potential. Perhaps cooperation through sharing of a common resource makes them energetically more competent?