Wnt/β-Catenin/TCF Pathway Is a Phase-Dependent Promoter of Colony Formation and Mesendodermal Differentiation During Human Somatic Cell Reprogramming

Generation of stable integration-free pig induced pluripotent stem cells under chemically defined culture condition

Genome integration-free pig induced pluripotent stem cells (iPSCs) bring tremendous value in pre-clinical testing of regenerative medicine, as well as conservation and exploitation of endangered or rare local pig idioplasmatic resources. However, due to a lack of appropriate culture medium, efficient induction and stable maintenance of pig iPSCs with practical value remains challenging. Here, we established an efficient induction system for exogenous gene-independent iPSCs under chemically defined culture condition previously used for generation of stable pig pre-gastrulation epiblast stem cells (pgEpiSCs). WNT suppression was found to play an essential role in establishment of exogenous gene-independent iPSCs. Strikingly, stable integration-free pig iPSCs could be established from pig somatic cells using episomal vectors in this culture condition. The iPSCs had pluripotency features and transcriptome characteristics approximating pgEpiSCs. More importantly, this induction system may be used to generate integration-free iPSCs from elderly disabled rare local pig somatic cells and the iPSCs could be gene-edited and used as donor cells for nuclear transfer. Our results provide novel insights into potential applications for genetic breeding of livestock species and pre-clinical evaluation of regenerative medicine.

Wnt signaling and the regulation of pluripotency

The role of Wnt signaling in stem cells has been mired in seemingly contradictory findings. On one hand, Wnt has been heralded as a self-renewal factor. On the other hand, Wnt's association with differentiation and lineage commitment is indisputable. This apparent contradiction is particularly evident in pluripotent stem cells, where Wnt promotes self-renewal as well as differentiation. To resolve this discrepancy one must delve into fundamental principles of pluripotency and gain an appreciation for the concept of pluripotency states, which exist in a continuum with intermediate metastable states, some of which have been stabilized in vitro. Wnt signaling is a critical regulator of transitions between pluripotent states. Here, we will discuss Wnt's roles in maintaining pluripotency, promoting differentiation, as well as stimulating reprogramming of somatic cells to an induced pluripotent state.

Assessment of the Hematopoietic Differentiation Potential of Human Pluripotent Stem Cells in 2D and 3D Culture Systems

BACKGROUND

In vitro methods for hematopoietic differentiation of human pluripotent stem cells (hPSC) are a matter of priority for the in-depth research into the mechanisms of early embryogenesis. So-far, published results regarding the generation of hematopoietic cells come from studies using either 2D or 3D culture formats, hence, it is difficult to discern their particular contribution to the development of the concept of a unique in vitro model in close resemblance to in vivo hematopoiesis.

AIM OF THE STUDY

To assess using the same culture conditions and the same time course, the potential of each of these two formats to support differentiation of human pluripotent stem cells to primitive hematopoiesis without exogenous activation of Wnt signaling.

METHODS

We used in parallel 2D and 3D formats, the same culture environment and assay methods (flow cytometry, IF, qPCR) to investigate stages of commitment and specification of mesodermal, and hemogenic endothelial cells to CD34 hematopoietic cells and evaluated their clonogenic capacity in a CFU system.

RESULTS

We show an adequate formation of mesoderm, an efficient commitment to hemogenic endothelium, a higher number of CD34 hematopoietic cells, and colony-forming capacity potential only in the 3D format-supported differentiation.

CONCLUSIONS

This study shows that the 3D but not the 2D format ensures the induction and realization by endogenous mechanisms of human pluripotent stem cells' intrinsic differentiation program to primitive hematopoietic cells. We propose that the 3D format provides an adequate level of upregulation of the endogenous Wnt/β-catenin signaling.

Molecular Profiling Associated with Calcium/Calmodulin-Dependent Protein Kinase Kinase 2 (CAMKK2)-Mediated Carcinogenesis in Gastric Cancer

Gastric cancer is the fifth most common cancer and the third leading cause of cancer-related death worldwide. We showed previously that calcium/calmodulin-dependent protein kinase kinase 2 (CAMKK2), a serine-threonine kinase, is highly expressed in gastric cancer and leads to progression. In the present study, we identified the molecular networks involved in CAMKK2-mediated progression of gastric adenocarcinoma. Treatment of gastric cancer cell lines with a CAMKK2 inhibitor, STO-609, resulted in decreased cell migration, invasion, and colony-forming ability and a G1/S-phase arrest. In addition, tandem mass tag (TMT)-based quantitative proteomic analysis resulted in the identification of 7609 proteins, of which 219 proteins were found to be overexpressed and 718 downregulated (1.5-fold). Our data identified several key downregulated proteins involved in cell division and cell proliferation, which included DNA replication licensing factors, replication factor C, origin recognition complex, replication protein A and GINS, and mesenchymal markers, upon CAMKK2 inhibition. Immunoblotting and immunofluorescence results showed concordance with our mass spectroscopy data. Taken together, our study supports CAMKK2 as a novel therapeutic target in gastric cancer.

Serous BMP8A has Clinical Significance in the Ultrasonic Diagnosis of Thyroid Cancer and Promotes Thyroid Cancer Cell Progression

OBJECTIVE

This study aims to discover a potential cytokine biomarker for early diagnosis of thyroid cancer.

METHODS

We employed data mining of The Cancer Genome Atlas (TCGA) and experimentally elucidated its mechanistic contributions. The differential expression genes (DEGs) between thyroid cancer and health population were analyzed with TCGA online bioinformatic tools. The relative expression of Bone Morphogenetic Protein 8A (BMP8A) was determined by real-time PCR in ultrasonic diagnosed thyroid cancer both in vivo and in vitro. The serous BMP8A content was quantified with an ELISA kit. Protein levels of BMP8A, OCLN, ZEB1, EZH2 and β-Actin were analyzed by Western blot. Cell viability was measured by the MTT assay, and anchorage-independent growth was measured by the soft agar colony formation assay. Cell migrative and invasive capacities were interrogated with transwell chamber assays.

RESULTS

We identified aberrantly high expression of BMP8A in thyroid cancer, which was associated with unfavorable prognosis and tumor progression. The serous BMP8A was also significantly up-regulated in thyroid cancer patients. Ectopic over-expression of BMP8A remarkably stimulated cell viability and anchorage-independent growth. Meanwhile, the migrative and invasive capacities were greatly increased in response to BMP8A over-expression. Mechanistically, we characterized the positive correlation between BMP8A and TCF7L1, and forced expression of TCF7L1 induced BMP8A expression in TPC-1 cells.

CONCLUSION

In summary, we have identified a novel biomarker for early diagnosis in addition to Ultrasound for thyroid cancer, which is subjected to TCF7L1 regulation.

Potential biomarkers for testicular germ cell tumour: Risk assessment, diagnostic, prognostic and monitoring of recurrence

Testicular germ cell tumour (TGCT) is considered a relatively rare malignancy usually occurring in young men between 15 and 35 years of age, and both genetic and environmental factors contribute to its development. The majority of patients are diagnosed in an early-stage of TGCTs with an elevated 5-year survival rate after therapy. However, approximately 25% of patients show an incomplete response to chemotherapy or tumours relapse. The current therapies are accompanied by several adverse effects, including infertility. Aside from classical serum biomarker, many studies reported novel biomarkers for TGCTs, but without proper validation. Cancer cells share many similarities with embryonic stem cells (ESCs), and since ESC genes are not transcribed in most adult tissues, they could be considered ideal candidate targets for cancer-specific diagnosis and treatment. Added to this, several microRNAs (miRNA) including miRNA-371-3p can be further investigated as a molecular biomarker for diagnosis and monitoring of TGCTs. In this review, we will illustrate the findings of recent investigations in novel TGCTs biomarkers applicable for risk assessment, screening, diagnosis, prognosis, prediction and monitoring of the relapse.

Transcriptomic Analysis of Naïve Human Embryonic Stem Cells Cultured in Three-Dimensional PEG Scaffolds

Naïve human embryonic stem cells (ESCs) are characterized by improved viability, proliferation, and differentiation capacity in comparison to traditionally derived primed human ESCs. However, currently used two-dimensional (2-D) cell culture techniques fail to mimic the three-dimensional (3-D) in vivo microenvironment, altering morphological and molecular characteristics of ESCs. Here, we describe the use of 3-D self-assembling scaffolds that support growth and maintenance of the naïve state characteristics of ESC line, Elf1. Scaffolds were formed via a Michael addition reaction upon the combination of two 8-arm polyethylene glycol (PEG) polymers functionalized with thiol (PEG-8-SH) and acrylate (PEG-8-Acr) end groups. 3-D scaffold environment maintained the naïve state and supported the long-term growth of ESCs. RNA-sequencing demonstrated significant changes in gene expression profiles between 2-D and 3-D grown cells. Gene ontology analysis revealed upregulation of biological processes involved in the regulation of transcription and translation, extracellular matrix organization, and chromatin remodeling in 3-D grown cells. 3-D culture conditions also induced upregulation of genes associated with Wnt and focal adhesion signaling, while p53 signaling pathway associated genes were downregulated. Our findings, for the first time, provide insight into the possible mechanisms of self-renewal of naïve ESCs stimulated by the transduction of mechanical signals from the 3-D microenvironment.

A Three-Dimensional Alzheimer's Disease Cell Culture Model Using iPSC-Derived Neurons Carrying A246E Mutation in PSEN1

Alzheimer's disease (AD) is a chronic brain disorder characterized by progressive intellectual decline and memory and neuronal loss, caused mainly by extracellular deposition of amyloid-β (Aβ) and intracellular accumulation of hyperphosphorylated tau protein, primarily in areas implicated in memory and learning as prefrontal cortex and hippocampus. There are two forms of AD, a late-onset form that affects people over 65 years old, and the early-onset form, which is hereditable and affect people at early ages ~45 years. To date, there is no cure for the disease; consequently, it is essential to develop new tools for the study of processes implicated in the disease. Currently, in vitro AD three-dimensional (3D) models using induced pluripotent stem cells (iPSC)-derived neurons have broadened the horizon for in vitro disease modeling and gained interest for mechanistic studies and preclinical drug discovery due to their potential advantages in providing a better physiologically relevant information and more predictive data for in vivo tests. Therefore, this study aimed to establish a 3D cell culture model of AD in vitro using iPSCs carrying the A246E mutation. We generated human iPSCs from fibroblasts from a patient with AD harboring the A246E mutation in the PSEN1 gene. Cell reprogramming was performed using lentiviral vectors with Yamanaka's factors (OSKM: Oct4, Sox2, Klf4, and c-Myc). The resulting iPSCs expressed pluripotency genes (such as Nanog and Oct4), alkaline phosphatase activity, and pluripotency stem cell marker expression, such as OCT4, SOX2, TRA-1-60, and SSEA4. iPSCs exhibited the ability to differentiate into neuronal lineage in a 3D environment through dual SMAD inhibition as confirmed by Nestin, MAP2, and Tuj1 neural marker expression. These iPSC-derived neurons harbored Aβ oligomers confirmed by Western Blot (WB) and immunostaining. With human iPSC-derived neurons able to produce Aβ oligomers, we established a novel human hydrogel-based 3D cell culture model that recapitulates Aβ aggregation without the need for mutation induction or synthetic Aβ exposure. This model will allow the study of processes implicated in disease spread throughout the brain, the screening of molecules or compounds with therapeutic potential, and the development of personalized therapeutic strategies.

NANOG and LIN28 dramatically improve human cell reprogramming by modulating LIN41 and canonical WNT activities

Human cell reprogramming remains extremely inefficient and the underlying mechanisms by different reprogramming factors are elusive. We found that NANOG and LIN28 (NL) synergize to improve OCT4, SOX2, KLF4 and MYC (OSKM)-mediated reprogramming by ∼76-fold and shorten reprogramming latency by at least 1 week. This synergy is inhibited by GLIS1 but reinforced by an inhibitor of the histone methyltransferase DOT1L (iDOT1L) to a ∼127-fold increase in TRA-1-60-positive (+) iPSC colonies. Mechanistically, NL serve as the main drivers of reprogramming in cell epithelialization, the expression of Let-7 miRNA target LIN41, and the activation of canonical WNT/β-CATENIN signaling, which can be further enhanced by iDOT1L treatment. LIN41 overexpression in addition to OSKM similarly promoted cell epithelialization and WNT activation in reprogramming, and a dominant-negative LIN41 mutation significantly blocked NL- and iDOT1L-enhanced reprogramming. We also found that NL- and iDOT1L-induced canonical WNT activation facilitates the initial development kinetics of iPSCs. However, a substantial increase in more mature, homogeneous TRA-1-60+ colony formation was achieved by inhibiting WNT activity at the middle-to-late-reprogramming stage. We further found that LIN41 can replace LIN28 to synergize with NANOG, and that the coexpression of LIN41 with NL further enhanced the formation of mature iPSCs under WNT inhibition. Our study established LIN41 and canonical WNT signaling as the key downstream effectors of NL for the dramatic improvement in reprogramming efficiency and kinetics, and optimized a condition for the robust formation of mature human iPSC colonies from primary cells.This article has an associated First Person interview with the first author of the paper.

FOXH1 Is Regulated by NANOG and LIN28 for Early-stage Reprogramming

FOXH1 is a primitive-streak specifier and ACTIVIN co-effector that plays an important role in development, and positively regulates the generation of human induced pluripotent stem cells (iPSCs) from somatic cells by OCT4, SOX2, KLF4, and MYC (OSKM) transduction. However, the mechanism and upstream regulation for FOXH1 expression in reprogramming are unclear. We found FOXH1 expression plays a significant role to enhance epithelial marker and suppress mesenchymal gene expression in OSKM-mediated human cell reprogramming. Furthermore, NANOG and LIN28 (NL) co-stimulate FOXH1 expression, which correlates with the enhanced reprogramming efficiency by NL-factors. FOXH1 expression is also stimulated by a specific inhibitor for H3K79 methyltransferase DOT1L (iDOT1L) but not by inhibition of the canonical WNT signaling. We further show that blocking endogenous FOXH1 expression eliminates the enhanced reprogramming effect by NL and iDOT1L. However, overexpressing FOXH1 in NL plus iDOT1L condition results in significantly reduced TRA-1-60 positively expressed cells and decreases pluripotent marker expression in reprogramming. Our study elucidated an essential role for properly stimulated FOXH1 expression by NANOG, LIN28, and H3K79 demethylation for dramatic enhancement of reprograming.

Promotion of ovarian cancer cell invasion, migration and colony formation by the miR‑21/Wnt/CD44v6 pathway

Ovarian cancer (OC) has the highest mortality rate among female malignant tumors, and OC commonly relapses and metastasizes. The mechanisms underlying the occurrence and development of ovarian cancer are numerous and complicated. The aim of the present study was to explore an important molecular mechanism that may provide a theoretical basis for the clinical treatment of ovarian cancer. In the present study, the expression level of miR‑21 was analyzed in clinical specimens, normal ovarian epithelial cells and three different ovarian cancer epithelial cell lines. Then, in vitro experiments were performed following the transient transfection of miR‑21 mimics and inhibitors into SKOV3 cells. RT‑PCR, western blot analysis, colony formation assay, and Transwell migration and invasion assays were used to explore the role of miR‑21 in ovarian cancer. In addition, Wnt signaling pathway inhibitors and activators were used to validate the hypothesis that the miR‑21/Wnt/CD44v6 pathway plays an important role in OC. In ovarian cancer tissues and cells, miR‑21 was highly expressed, and the high expression of miR‑21 could activate the Wnt signaling pathway to regulate the expression of CD44v6 and affect the proliferation, invasion and migration of OC cells. miR‑21 regulated the expression of CD44v6 by activating the Wnt signaling pathway, which plays an important role in the development of ovarian cancer. These findings provide a potential new therapeutic target for the clinical diagnosis and treatment of ovarian cancer.

An orally antitumor chalcone hybrid inhibited HepG2 cells growth and migration as the tubulin binding agent

Liver cancer is a kind of high mortality cancer due to the difficulty of early diagnosis. It is necessary to develop the anticancer agents to treat liver cancer. Here, a novel chalcone derivative was synthesized and evaluated for anticancer activity in vitro against liver cancer cell lines (HepG2, SNU-423, SMMC7221, and SNU-398). The chalcone hybrid 9 displayed the antiproliferative effect against HepG2, SNU-423, SMMC7221 and SNU-398 cells with IC₅₀ values of 0.9 μM, 2.7 μM, 6.2 μM and 4.6 μM, respectively. Cellular mechanisms showed that derivative 9 could obviously inhibit HepG2 cells growth and colony formation in a concentration-dependent manner. Analogue 9 inhibited the migration by regulating the expression levels of migration-releated markers and transcription factors (Snail and Slug). Tubulin polymerization inhibition assay illustrated that chalcone hybrid 9 might be a potent tubulin polymerization inhibitor. Importantly, compound 9 displayed the antitumor activity against liver cancer HepG2 cells in vivo with the low toxicity toward mice. Therefore, compound 9 as a novel tubulin polymerization inhibitor deserves further investigation to treat liver cancer. Graphical abstract Compound 9 displayed the antitumor activity against liver cancer HepG2 cells in vivo and low toxicity toward mice Figure: Orally antitumor chalcone hybrid 9 inhibited HepG2 cells growth and migration as the tubulin binding agent.