The epithelial-mesenchymal transition (EMT), one of the main mechanisms underlying development of cancer metastasis, induces stem-like properties in epithelial cells. Bmi1 is a polycomb-group protein that maintains self-renewal, and is frequently overexpressed in human cancers. Here, we show the direct regulation of BMI1 by the EMT regulator, Twist1. Furthermore, Twist1 and Bmi1 were mutually essential to promote EMT and tumour-initiating capability. Twist1 and Bmi1 act cooperatively to repress expression of both E-cadherin and p16INK4a. In patients with head and neck cancers, increased levels of both Twist1 and Bmi1 correlated with downregulation of E-cadherin and p16INK4a, and was associated with the worst prognosis. These results suggest that Twist1-induced EMT and tumour-initiating capability in cancer cells occurs through chromatin remodelling, which leads to unfavourable clinical outcomes.

Liver transplantation is the only definitive treatment for end-stage cirrhosis and fulminant liver failure, but the lack of available donor livers is a major obstacle to liver transplantation. Recently, induced pluripotent stem cells (iPSCs) derived from the reprogramming of somatic fibroblasts, have been shown to resemble embryonic stem (ES) cells in that they have pluripotent properties and the potential to differentiate into all cell lineages in vitro, including hepatocytes. Thus, iPSCs could serve as a favorable cell source for a wide range of applications, including drug toxicity testing, cell transplantation, and patient-specific disease modeling. Here, we describe an efficient and rapid three-step protocol that is able to rapidly generate hepatocyte-like cells from human iPSCs. This occurs because the endodermal induction step allows for more efficient and definitive endoderm cell formation. We show that hepatocyte growth factor (HGF), which synergizes with activin A and Wnt3a, elevates the expression of the endodermal marker Foxa2 (forkhead box a2) by 39.3% compared to when HGF is absent (14.2%) during the endodermal induction step. In addition, iPSC-derived hepatocytes had a similar gene expression profile to mature hepatocytes. Importantly, the hepatocyte-like cells exhibited cytochrome P450 3A4 (CYP3A4) enzyme activity, secreted urea, uptake of low-density lipoprotein (LDL), and possessed the ability to store glycogen. Moreover, the hepatocyte-like cells rescued lethal fulminant hepatic failure in a nonobese diabetic severe combined immunodeficient mouse model. Conclusion: We have established a rapid and efficient differentiation protocol that is able to generate functional hepatocyte-like cells from human iPSCs. This may offer an alternative option for treatment of liver diseases.

Asymmetrical cell division (ACD) maintains the proper number of stem cells to ensure self-renewal. In cancer cells, the deregulation of ACD disrupts the homeostasis of the stem cell pool and promotes tumour growth. However, this mechanism is unclear. Here, we show a reduction of ACD in spheroid-derived colorectal cancer stem cells (CRCSCs) compared with differentiated cancer cells. The epithelial-mesenchymal transition (EMT) inducer Snail is responsible for the ACD-to-symmetrical cell division (SCD) switch in CRCSCs. Mechanistically, Snail induces the expression of microRNA-146a (miR-146a) through the β-catenin-TCF4 complex. miR-146a targets Numb to stabilize β-catenin, which forms a feedback circuit to maintain Wnt activity and directs SCD. Interference with the Snail-miR-146a–β-catenin loop by inhibiting the MEK or Wnt activity reduces the symmetrical division of CRCSCs and attenuates tumorigenicity. In colorectal cancer patients, the Snail(High)Numb(Low) profile is correlated with cetuximab resistance and a poorer prognosis. This study elucidates a unique mechanism of EMT-induced CRCSC expansion.

Mesenchymal stem cells (MSCs) found in bone marrow (BM)-MSCs are an attractive source for the regeneration of damaged tissues. Alternative postnatal, perinatal, and fetal sources of MSCs are also under intensive investigation. MSCs from the Wharton's jelly matrix of umbilical cord (WJ)-MSCs have higher pancreatic and endothelial differentiation potentials than BM-MSCs, but the underlying mechanisms are poorly understood. We compared the gene expression profiles, enriched canonical pathways, and genetic networks of BM-MSCs and WJ-MSCs. WJ-MSCs express more angiogenesis- and growth-related genes including epidermal growth factor and FLT1, whereas BM-MSCs express more osteogenic genes such as RUNX2, DLX5, and NPR3. The gene expression pattern of BM-MSCs is more similar to osteoblasts than WJ-MSCs, suggesting a better osteogenic potential. In contrast, WJ-MSCs are more primitive because they share more common genes with embryonic stem cells. BM-MSCs are more sensitive to environmental stimulations because their molecular signatures altered more significantly in different culture conditions. WJ-MSCs express genes enriched in vascular endothelial growth factor and PI3K-NFκB canonical pathways, whereas BM-MSCs express genes involved in antigen presentation and chemokine/cytokine pathways. Drylab results could be verified by wetlab experiments, in which BM-MSCs were more efficient in osteogenic and adipogenic differentiation, whereas WJ-MSCs proliferated better. WJ-MSCs thus constitute a promising option for angiogenesis, whereas BM-MSCs in bone remodeling. Our results reveal systematically the underlying genes and regulatory networks of 2 MSCs from unique ontological and anatomical origins, as well as the resulted phenotypes, thereby providing a better basis for cell-based therapy and the following mechanistic studies on MSC biology.

BackgroundEndothelial progenitor cells (EPCs) play a fundamental role in post-natal vascular repair. Currently EPCs are defined as either early and late EPCs based on their biological properties and their time of appearance during in vitro culture. EPCs are rare and therefore optimizing isolation and culture is required before they can be applied as part of clinical therapies.ResultsWe compared the gene profiles of early/late EPCs to their ancestors CD133+ or CD34+ stem cells and to matured endothelial cells pinpointing novel biomarkers and stemness genes. Late EPCs were enriched with proliferation and angiogenesis genes, participating in endothelial tubulogenesis and hence neovascularization. Early EPCs expressed abundant inflammatory cytokines and paracrine angiogenic factors, thereby promoting angiogenesis in a paracrine manner. Transcription factors involved in EPC stemness were pinpointed in early EPCs (MAF/MAFB) and in late EPCs (GATA6/IRF6).ConclusionsThe detailed mRNA expression profiles and functional module analysis for different EPCs will help the development of novel therapeutic modalities targeting cardiovascular disease, tumor angiogenesis and various ischemia-related diseases.

BRAF mutation is an independent prognostic biomarker for colorectal liver metastasectomy.

BackgroundMicroRNAs (miRNAs) have emerged as master regulators of angiogenesis and other cancer-related events. Discovering new angiogenesis-regulating microRNAs (angiomiRs) will eventually help in developing new therapeutic strategies for tumor angiogenesis and cardiovascular diseases. Kaposi’s sarcoma (KS), which is induced by the etiological infectious agent KS-associated herpesvirus (KSHV), is a peculiar neoplasm that expresses both blood and lymphatic endothelial markers and possesses extensive neovasculature. Using KSHV and its proteins as baits will be an efficient way to discover new angiomiRs in endothelial cells. Kaposin B is one of the latent viral genes and is expressed in all KSHV tumor cells. Since Kaposin B is a nuclear protein with no DNA-binding domain, it may regulate gene expression by incorporating itself into a transcription complex.ResultsWe demonstrated that c-Myc and Kaposin B form a transcription complex and bind to the miR-221/-222 promoter, thereby affecting their expression and anti-angiogenic ability. By small RNA sequencing (smRNA-Seq), we revealed that 72.1 % (173/240) of Kaposin B up-regulated and 46.5 % (113/243) of Kaposin B down-regulated known miRNAs were regulated by c-Myc. We also found that 77 novel miRNA were up-regulated and 28 novel miRNAs were down-regulated in cells expressing both c-Myc and Kaposin B compared with cells expressing Kaposin B only. The result was confirmed by RNA-IP-seq data.ConclusionsOur study identifies known and novel c-Myc-regulated microRNAs and reveals that a c-Myc-oriented program is coordinated by Kaposin B in KSHV-infected cells.Electronic supplementary materialThe online version of this article (doi:10.1186/s12918-015-0242-3) contains supplementary material, which is available to authorized users.

Dysfunction and reduction of circulating endothelial progenitor cell (EPC) is correlated with the onset of cardiovascular disorders including coronary artery disease (CAD). VEGF is a known mitogen for EPC to migrate out of bone marrow to possess angiogenic activities, and the plasma levels of VEGF are inversely correlated to the progression of CAD. Circulating microRNAs (miRNAs) in patient body fluids have recently been considered to hold the potential of being novel disease biomarkers and drug targets. However, how miRNAs and VEGF cooperate to regulate CAD progression is still unclear. Through the small RNA sequencing (smRNA-seq), we deciphered the miRNome patterns of EPCs with different angiogenic activities, hypothesizing that miRNAs targeting VEGF must be more abundant in EPCs with lower angiogenic activities. Candidates of anti-VEGF miRNAs, including miR-361-5p and miR-484, were enriched in not only diseased EPCs but also the plasma of CAD patients. However, we found out only miR-361-5p, but not miR-484, was able to suppress VEGF expression and EPC activities. Reporter assays confirmed the direct binding and repression of miR-361-5p to the 3′-UTR of VEGF mRNA. Knock down of miR-361-5p not only restored VEGF levels and angiogenic activities of diseased EPCs in vitro, but further promoted blood flow recovery in ischemic limbs of mice. Collectively, we discovered a miR-361-5p/VEGF-dependent regulation that could help to develop new therapeutic modalities not only for ischemia-related diseases but also for tumor angiogenesis.