Dynamic regulation of the cancer stem cell compartment by Cripto-1 in colorectal cancer

Abstract

Stemness was recently depicted as a dynamic condition in normal and tumor cells. We found that the embryonic protein Cripto-1 (CR1) was expressed by normal stem cells at the bottom of colonic crypts and by cancer stem cells (CSCs) in colorectal tumor tissues. CR1-positive populations isolated from patient-derived tumor spheroids exhibited increased clonogenic capacity and expression of stem-cell-related genes. CR1 expression in tumor spheroids was variable over time, being subject to a complex regulation of the intracellular, surface and secreted protein, which was related to changes of the clonogenic capacity at the population level. CR1 silencing induced CSC growth arrest in vitro with a concomitant decrease of Src/Akt signaling, while in vivo it inhibited the growth of CSC-derived tumor xenografts and reduced CSC numbers. Importantly, CR1 silencing in established xenografts through an inducible expression system decreased CSC growth in both primary and metastatic tumors, indicating an essential role of CR1 in the regulation the CSC compartment. These results point to CR1 as a novel and dynamically regulated effector of stem cell functions in colorectal cancer.

Cancer Stem Cell-Based Models of Colorectal Cancer Reveal Molecular Determinants of Therapy Resistance

“…Previous studies by our and other laboratories reported that multicellular spheroid suspensions enriched in CSCs could be obtained by the selective culture of cells extracted from colorectal tumor specimens in serum-free media [6,[15][16][17][18]. We improved previous culture methods through supplementation with factors identified by Sato et al (nicotinamide and Y-27632), which are also essential for the in vitro growth of normal intestinal stem cells [19], reaching approximately 40% of success in the generation of CSC cultures from tumor specimens (supplemental online Table 1).…”

Cell surface galectin-3 defines a subset of chemoresistant gastrointestinal tumor-initiating cancer cells with heightened stem cell characteristics

“…1, 2, 3 The identification and isolation of CSC, however, remains challenging. Many reputed stem cell markers were empirically determined, may be restricted to certain models, and controversy exists regarding which markers accurately define CSC.…”

Biochemical and Cellular Analysis Reveals Ligand Binding Specificities, a Molecular Basis for Ligand Recognition, and Membrane Association-dependent Activities of Cripto-1 and Cryptic

“…Using recombinant human Cripto-1 and mouse Cryptic, we discovered both molecules interact with a limited number of TGF-␤ family ligands. Cripto-1 interacted with Nodal and BMP-4, Cryptic interacted with Activin B. Intriguingly, a recent study found that Cripto-1 is expressed at the bottom of colonic crypts in normal human and mouse colon (55), indicating it could regulate signaling of BMP-4 expressed by intravillus and intercrypt mesenchymal cells that are adjacent to intestinal stem cells (56). It has been suggested that Cripto-1 and Cryptic have similar, possibly redundant functions.…”