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Background: Despite their lethality and ensuing clinical and therapeutic relevance, circulating tumor cells (CTCs) from colorectal carcinoma (CRC) remain elusive, poorly characterized biological entities. Methods and findings: We perfected a cell system of stable, primary lines from human CRC showing that they possess the full complement of ex- and in-vivo, in xenogeneic models, characteristics of CRC stem cells (CCSCs). Here we show how tumor-initiating, CCSCs cells can establish faithful orthotopic phenocopies of the original disease, which contain cells that spread into the circulatory system. While in the vascular bed, these cells retain stemness, thus qualifying as circulating CCSCs (cCCSCs). This is followed by the establishment of lesions in distant organs, which also contain resident metastatic CCSCs (mCCSCs). Interpretation: Our results support the concept that throughout all the stages of CRC, stemness is retained as a continuous property by some of their tumor cells. Importantly, we describe a useful standardized model that can enable isolation and stable perpetuation of human CRC's CCSCs, cCCSCs and mCCSCs, providing a useful platform for studies of CRC initiation and progression that is suitable for the discovery of reliable stage-specific biomarkers and the refinement of new patient-tailored therapies. Fund: This work was financially supported by grants from “Ministero della Salute Italiano”(GR-2011-02351534, RC1703IC36 and RC1803IC35) to Elena Binda and from “Associazione Italiana Cancro” (IG-14368) Angelo L. Vescovi. None of the above funders have any role in study design, data collection, data analysis, interpretation, writing the project. Keywords: Human colorectal carcinoma (CRC), Stemness, CRC stem cells, CRC circulating stem cells, CRC metastatic stem cells, CRC biology and biomarkers, Anti-CRC SCs strategies

Defective primary ciliogenesis or cilium stability forms the basis of human ciliopathies, including Joubert syndrome (JS), with defective cerebellar vermis development. We performed a high-content genome-wide small interfering RNA (siRNA) screen to identify genes regulating ciliogenesis as candidates for JS. We analyzed results with a supervised-learning approach, using SYSCILIA gold standard, Cildb3.0, a centriole siRNA screen and the GTex project, identifying 591 likely candidates. Intersection of this data with whole exome results from 145 individuals with unexplained JS identified six families with predominantly compound heterozygous mutations in KIAA0586. A c.428del base deletion in 0.1% of the general population was found in trans with a second mutation in an additional set of 9 of 163 unexplained JS patients. KIAA0586 is an orthologue of chick Talpid3, required for ciliogenesis and Sonic hedgehog signaling. Our results uncover a relatively high frequency cause for JS and contribute a list of candidates for future gene discoveries in ciliopathies.