GSE40174
RNA sequencing of circulating tumour cells implicates WNT signaling in pancreatic cancer metastasis (human data)
Circulating tumour cells (CTCs) shed into blood from primary cancers include putative precursors that initiate distal metastases. While these cells are extraordinarily rare, they may identify cellular pathways contributing to the blood-borne dissemination of cancer. Here, we adapted a microfluidic device for efficient capture of CTCs from an endogenous mouse pancreatic cancer model and subjected CTCs to single-molecule RNA sequencing, identifying Wnt2 as enriched in CTCs. Expression of Wnt2 in pancreatic cancer cells suppresses anoikis, enhances anchorage-independent sphere formation, and increases metastatic propensity in vivo. The effect of Wnt2 is correlated with fibronectin upregulation, and it is mediated in part through non-canonical Wnt signaling and suppressed by inhibition of the Map3k7 (Tak1) kinase, an integrator of Wnt, BMP and TGF-beta signaling. In humans, formation of non-adherent tumour spheres by pancreatic cancer cells is associated with upregulation of multiple Wnt genes, and pancreatic CTCs revealed significant enrichment for non-canonical Wnt signaling in 5 of 11 cases. Thus, molecular analysis of CTCs may identify novel therapeutic targets to prevent the distal spread of cancer. Overall design: Expression profiling of circulating tumor cells in human pancreatic cancer patients support a hypothesis that WNT signaling plays a role in pancreatic cancer metastasis.