Epithelial-mesenchymal plasticity-engaging stemness in an interplay of phenotypes

Modeling stress-induced responses: plasticity in continuous state space and gradual clonal evolution

Mathematical models of cancer and bacterial evolution have generally stemmed from a gene-centric framework, assuming clonal evolution via acquisition of resistance-conferring mutations and selection of their corresponding subpopulations. More recently, the role of phenotypic plasticity has been recognized and models accounting for phenotypic switching between discrete cell states (e.g., epithelial and mesenchymal) have been developed. However, seldom do models incorporate both plasticity and mutationally driven resistance, particularly when the state space is continuous and resistance evolves in a continuous fashion. In this paper, we develop a framework to model plastic and mutational mechanisms of acquiring resistance in a continuous gradual fashion. We use this framework to examine ways in which cancer and bacterial populations can respond to stress and consider implications for therapeutic strategies. Although we primarily discuss our framework in the context of cancer and bacteria, it applies broadly to any system capable of evolving via plasticity and genetic evolution.

"Beyond transcription: How post-transcriptional mechanisms drive neural crest EMT"

The neural crest is a stem cell population that originates from the ectoderm during the initial steps of nervous system development. Neural crest cells delaminate from the neuroepithelium by undergoing a spatiotemporally regulated epithelial-mesenchymal transition (EMT) that proceeds in a coordinated wave head-to-tail to exit from the neural tube. While much is known about the transcriptional programs and membrane changes that promote EMT, there are additional levels of gene expression control that neural crest cells exert at the level of RNA to control EMT and migration. Yet, the role of post-transcriptional regulation, and how it drives and contributes to neural crest EMT, is not well understood. In this mini-review, we explore recent advances in our understanding of the role of post-transcriptional regulation during neural crest EMT.

Therapeutic Potential of Regorafenib in Cisplatin-Resistant Bladder Cancer with High Epithelial-Mesenchymal Transition and Stemness Properties

Bladder cancer is becoming one of the most common malignancies across the world. Although treatment strategy has been continuously improved, which has led to cisplatin-based chemotherapy becoming the standard medication, cancer recurrence and metastasis still occur in a high proportion of patients because of drug resistance. The high efficacy of regorafenib, a broad-spectrum kinase inhibitor, has been evidenced in treating a variety of advanced cancers. Hence, this study investigated whether regorafenib could also effectively antagonize the survival of cisplatin-resistant bladder cancer and elucidate the underlying mechanism. Two types of cisplatin-resistant bladder cancer cells, T24R1 and T24R2, were isolated from T24 cisplatin-sensitive bladder cancer cells. These cells were characterized, and T24R1- and T24R2-xenografted tumor mice were created to examine the therapeutic efficacy of regorafenib. T24R1 and T24R2 cells exhibited higher expression levels of epithelial-mesenchymal transition (EMT) and stemness markers compared to the T24 cells, and regorafenib could simultaneously inhibit the viability and the expression of EMT/stemness markers of both T24R1 and T24R2 cells. Moreover, regorafenib could efficiently arrest the cell cycle, promote apoptosis, and block the transmigration/migration capabilities of both types of cells. Finally, regorafenib could significantly antagonize the growth of T24R1- and T24R2-xenografted tumors in mice. These results demonstrated the therapeutic efficacy of regorafenib in cisplatin-resistant bladder cancers. This study, thus, provides more insights into the mechanism of action of regorafenib and demonstrates its great potential in the future treatment of cisplatin-resistant advanced bladder cancer patients.

Stochastic epithelial-mesenchymal transitions diversify non-cancerous lung cell behaviours

Epithelial-mesenchymal plasticity (EMP) is a hallmark of cancer. By enabling cells to shift between different morphological and functional states, EMP promotes invasion, metastasis and therapy resistance. We report that near-diploid non-cancerous human epithelial lung cells spontaneously shift along the EMP spectrum without genetic changes. Strikingly, more than half of single cell-derived clones adopt a mesenchymal morphology. We independently characterise epithelial-like and mesenchymal-like clones. Mesenchymal clones lose epithelial markers, display larger cell aspect ratios and lower motility, with mostly unaltered proliferation rates. Stemness marker expression and metabolic rewiring diverge independently of phenotypes. In 3D culture, more epithelial clones become mesenchymal-like. Thus, non-cancerous epithelial cells may acquire cancer metastasis-associated features prior to genetic alterations and cancerous transformation.

In vitro cross-talk between metastasis-competent circulating tumor cells and platelets in colon cancer: a malicious association during the harsh journey in the blood

Background: Platelets are active players in hemostasis, coagulation and also tumorigenesis. The cross-talk between platelets and circulating tumor cells (CTCs) may have various pro-cancer effects, including promoting tumor growth, epithelial-mesenchymal transition (EMT), metastatic cell survival, adhesion, arrest and also pre-metastatic niche and metastasis formation. Interaction with CTCs might alter the platelet transcriptome. However, as CTCs are rare events, the cross-talk between CTCs and platelets is poorly understood. Here, we used our established colon CTC lines to investigate the colon CTC-platelet cross-talk in vitro and its impact on the behavior/phenotype of both cell types. Methods: We exposed platelets isolated from healthy donors to thrombin (positive control) or to conditioned medium from three CTC lines from one patient with colon cancer and then we monitored the morphological and protein expression changes by microscopy and flow cytometry. We then analyzed the transcriptome by RNA-sequencing of platelets indirectly (presence of a Transwell insert) co-cultured with the three CTC lines. We also quantified by reverse transcription-quantitative PCR the expression of genes related to EMT and cancer development in CTCs after direct co-culture (no Transwell insert) with platelets. Results: We observed morphological and transcriptomic changes in platelets upon exposure to CTC conditioned medium and indirect co-culture (secretome). Moreover, the expression levels of genes involved in EMT (p < 0.05) were decreased in CTCs co-cultured with platelets, but not of genes encoding mesenchymal markers (FN1 and SNAI2). The expression levels of genes involved in cancer invasiveness (MYC, VEGFB, IL33, PTGS2, and PTGER2) were increased. Conclusion: For the first time, we studied the CTC-platelet cross-talk using our unique colon CTC lines. Incubation with CTC conditioned medium led to platelet aggregation and activation, supporting the hypothesis that their interaction may contribute to preserve CTC integrity during their journey in the bloodstream. Moreover, co-culture with platelets influenced the expression of several genes involved in invasiveness and EMT maintenance in CTCs.

Environmental Determinants of Ferroptosis in Cancer

Given the enormous suffering and death associated with human cancers, there is an urgent need for novel therapeutic approaches to target tumor growth and metastasis. While initial efforts have focused on the dysregulated oncogenic program of cancer cells, recent focus has been on the modulation and targeting of many "cancer-friendly," non-genetic tumor microenvironmental factors, which support and enable tumor progression and metastasis. Two prominent examples are anti-angiogenesis and immunotherapy that target tumor-supporting vascularization and the immune-suppressive tumor microenvironment (TME), respectively. Lately, there has been significant interest in the therapeutic potential of ferroptosis, a natural tumor suppression mechanism that normally occurs as a result of oxidative stress, iron imbalance, and accumulation of lipid peroxides. While numerous studies have identified various cell intrinsic mechanisms to protect or promote ferroptosis, the role of various TME stress factors are also recently recognized to modulate the tumor cells' susceptibility to ferroptosis. This review aims to compile and highlight evidence of these factors, how various TME stresses affect ferroptosis, and their implications in various stages of tumor development and expected response to ferroptosis-triggering therapeutics under development. Consequently, understanding ways to enhance ferroptosis sensitivity both intracellularly and in the TME may optimize therapeutic sensitivity to minimize or prevent tumor growth and metastasis.

Melatonin Inhibits EMT in Bladder Cancer by Targeting Autophagy

Melatonin, a naturally biosynthesized molecule secreted by the pineal gland, exhibits antitumor activities against several different types of cancer. The mechanisms of action of melatonin against tumor progression involve cellular apoptosis, antimetastatic activity, antioxidant and mutagenic effects, antiangiogenic activity, and the restoration of cancer immune surveillance. Melatonin has anticancer activity when administered alone or in combination with standard chemotherapeutic agents, with measurable improvements seen in the clinical endpoints of tumor regression and patient survival. However, scant clinical evidence supports the use of melatonin in bladder cancer treatment. Our study has found that melatonin treatment suppresses the bladder cancer cell migratory ability by inhibiting the epithelial-mesenchymal transition (EMT) process, which appears to be linked to melatonin-induced decreases in bladder cancer cell autophagy. Finally, an evaluation of in vivo melatonin-induced antitumor effects in an orthotopic animal model of bladder cancer indicated that melatonin treatment slightly prolonged the survival of tumor-bearing mice. Our study offers novel insights into the use of melatonin in bladder cancer treatment.

Interaction between tumor microenvironment, autophagy, and epithelial-mesenchymal transition in tumor progression

Tumor microenvironment (TME) is the ecosystem surrounding a tumor to influence tumor cells' growth, metastasis and immunological battlefield, in which the tumor systems fight against the body system. TME has been considered as the essential link between the tumorigenesis and development of neoplasm. Both nutrients intake and tumor progression to malignancy require the participation of components in TME. Epithelial-mesenchymal transition (EMT) is a key step in the metastasis of tumor cells. Cells that lost polarity and acquired migration ability are prone to metastasize. Autophagy is an important self-protective mechanism in tumor cells and a necessity for the tumor cells to respond to harmful stress. Protective autophagy benefits tumor cells while abnormal autophagy leads to cell injury or death. EMT and autophagy are directly regulated by TME. To date, there are numerous studies on TME, autophagy and EMT separately, but few on their complex interrelationships. This review aims to comprehensively analyze the existing mechanisms and convincing evidence so far to seek novel therapeutic strategies and research directions.

PillarX: A Microfluidic Device to Profile Circulating Tumor Cell Clusters Based on Geometry, Deformability, and Epithelial State

Circulating tumor cell (CTC) clusters are associated with increased metastatic potential and worse patient prognosis, but are rare, difficult to count, and poorly characterized biophysically. The PillarX device described here is a bimodular microfluidic device (Pillar-device and an X-magnetic device) to profile single CTCs and clusters from whole blood based on their size, deformability, and epithelial marker expression. Larger, less deformable clusters and large single cells are captured in the Pillar-device and sorted according to pillar gap sizes. Smaller, deformable clusters and single cells are subsequently captured in the X-device and separated based on epithelial marker expression using functionalized magnetic nanoparticles. Clusters of established and primary breast cancer cells with variable degrees of cohesion driven by different cell-cell adhesion protein expression are profiled in the device. Cohesive clusters exhibit a lower deformability as they travel through the pillar array, relative to less cohesive clusters, and have greater collective invasive behavior. The ability of the PillarX device to capture clusters is validated in mouse models and patients of metastatic breast cancer. Thus, this device effectively enumerates and profiles CTC clusters based on their unique geometrical, physical, and biochemical properties, and could form the basis of a novel prognostic clinical tool.

Epithelial-Mesenchymal Transition-Inducing Factors Involved in the Progression of Lung Cancers

Although there have been advances in cancer therapy and surgical improvement, lung cancer has the lowest survival rate (19%) at all stages. This is because most patients are diagnosed with concurrent metastasis, which occurs due to numerous related reasons. Especially, lung cancer is one of the most common and malignant cancers in the world. Although there are advanced therapeutic strategies, lung cancer remains one of the main causes of cancer death. Recent work has proposed that epithelial-mesenchymal transition (EMT) is the main cause of metastasis in most cases of human cancers including lung cancer. EMT involves the conversion of epithelial cells, wherein the cells lose their epithelial abilities and become mesenchymal cells involved in embryonic development, such as gastrulation and neural crest formation. In addition, recent research has indicated that EMT contributes to altering the cancer cells into cancer stem cells (CSCs). Although EMT is important in the developmental stages, this process also activates lung cancer progression, including complicated and diverse signaling pathways. Despite the numerous investigations on signaling pathways involved in the progression of lung cancer, this malignancy is considered critical for treatment. EMT in lung cancer involves many transcription factors and inducers, for example, Snail, TWIST, and ZEB are the master regulators of EMT. EMT-related factors and signaling pathways are involved in the progression of lung cancer, proposing new approaches to lung cancer therapy. In the current review, we highlight the signaling pathways implicated in lung cancer and elucidate the correlation of these pathways, indicating new insights to treat lung cancer and other malignancies.

Evolution of HER2-positive mammary carcinoma: HER2 loss reveals claudin-low traits in cancer progression

HER2-positive breast cancers may lose HER2 expression in recurrences and metastases. In this work, we studied cell lines derived from two transgenic mammary tumors driven by human HER2 that showed different dynamics of HER2 status. MamBo89HER2^stable cell line displayed high and stable HER2 expression, which was maintained upon in vivo passages, whereas MamBo43HER2^labile cell line gave rise to HER2-negative tumors from which MamBo38HER2^loss cell line was derived. Both low-density seeding and in vitro trastuzumab treatment of MamBo43HER2^labile cells induced the loss of HER2 expression. MamBo38HER2^loss cells showed a spindle-like morphology, high stemness and acquired in vivo malignancy. A comprehensive molecular profile confirmed the loss of addiction to HER2 signaling and acquisition of an EMT signature, together with increased angiogenesis and migration ability. We identified PDGFR-B among the newly expressed determinants of MamBo38HER2^loss cell tumorigenic ability. Sunitinib inhibited MamBo38HER2^loss tumor growth in vivo and reduced stemness and IL6 production in vitro. In conclusion, HER2-positive mammary tumors can evolve into tumors that display distinctive traits of claudin-low tumors. Our dynamic model of HER2 status can lead to the identification of new druggable targets, such as PDGFR-B, in order to counteract the resistance to HER2-targeted therapy that is caused by HER2 loss.

Tumor Heterogeneity and Consequences for Bladder Cancer Treatment

Simple Summary

Bladder cancer is a heterogeneous disease that is composed of epithelia with varying transcriptional, mutational and lineage signatures. The epithelia of bladder tumors can also undergo pronounced changes in transcriptional and phenotypical qualities in response to progression, treatment related stresses and cues from the tumor microenvironment (TME). We hypothesize that changes in epithelial tumor heterogeneity (EpTH) occur due to the evolving content of epithelial subpopulations through both Darwinian and Lamarckian-like natural selection processes. We further conjecture that lineage-defined subpopulations can change through nongenomic and genomic cellular mechanisms that include cellular plasticity and acquired driver mutations, respectively. We propose that such processes are dynamic and contribute towards clinical treatment challenges including progression to drug resistance. In this article, we assess mechanisms that may support dynamic tumor heterogeneity with the overall goal of emphasizing the application of these concepts to the clinical setting.

Abstract

Acquired therapeutic resistance remains a major challenge in cancer management and associates with poor oncological outcomes in most solid tumor types. A major contributor is tumor heterogeneity (TH) which can be influenced by the stromal; immune and epithelial tumor compartments. We hypothesize that heterogeneity in tumor epithelial subpopulations—whether de novo or newly acquired—closely regulate the clinical course of bladder cancer. Changes in these subpopulations impact the tumor microenvironment including the extent of immune cell infiltration and response to immunotherapeutics. Mechanisms driving epithelial tumor heterogeneity (EpTH) can be broadly categorized as mutational and non-mutational. Mechanisms regulating lineage plasticity; acquired cellular mutations and changes in lineage-defined subpopulations regulate stress responses to clinical therapies. If tumor heterogeneity is a dynamic process; an increased understanding of how EpTH is regulated is critical in order for clinical therapies to be more sustained and durable. In this review and analysis, we assess the importance and regulatory mechanisms governing EpTH in bladder cancer and the impact on treatment response.

Comparative Analysis of Vascular Mimicry in Head and Neck Squamous Cell Carcinoma: In Vitro and In Vivo Approaches

Tissue vasculature provides the main conduit for metastasis in solid tumours including head and neck squamous cell carcinoma (HNSCC). Vascular mimicry (VM) is an endothelial cell (EC)-independent neovascularization pattern, whereby tumour cells generate a perfusable vessel-like meshwork. Yet, despite its promising clinical utility, there are limited approaches to better identify VM in HNSCC and what factors may influence such a phenomenon in vitro. Therefore, we employed different staining procedures to assess their utility in identifying VM in tumour sections, wherein mosaic vessels may also be adopted to further assess the VM-competent cell phenotype. Using 13 primary and metastatic HNSCC cell lines in addition to murine- and human-derived matrices, we elucidated the impact of the extracellular matrix, tumour cell type, and density on the formation and morphology of cell-derived tubulogenesis in HNSCC. We then delineated the optimal cell numbers needed to obtain a VM meshwork in vitro, which revealed cell-specific variations and yet consistent expression of the EC marker CD31. Finally, we proposed the zebrafish larvae as a simple and cost-effective model to evaluate VM development in vivo. Taken together, our findings offer a valuable resource for designing future studies that may facilitate the therapeutic exploitation of VM in HNSCC and other tumours.

Circulating Tumor Cells Expressing Krüppel-Like Factor 8 and Vimentin as Predictors of Poor Prognosis in Pancreatic Cancer Patients

BACKGROUND

Circulating tumor cells (CTCs) with an epithelial-mesenchymal transition phenotype in peripheral blood may be a useful marker of carcinomas with poor prognosis. The aim of this study was to determine the prognostic significance of CTCs expressing Krüppel-like factor 8 (KLF8) and vimentin in pancreatic cancer (PC).

METHODS

CTCs were isolated by immunomagnetic separation from the peripheral blood of 40 PC patients before undergoing surgical resection. Immunocytochemistry was performed to identify KLF8⁺ and vimentin⁺ CTCs. The associations between CTCs and time to recurrence (TTR), clinicopathologic factors, and survival were assessed. Univariate and multivariate analyzes were performed to identify risk factors.

RESULTS

Patients with CTCs (n = 30) had a higher relapse rate compared to those without (n = 10) (70.0% vs 20.0%; P < 0.01). The proportion of KLF8⁺/vimentin⁺ CTCs to total CTCs was inversely related to TTR (r = -0.646; P < 0.01); TTR was reduced in patients with > 50% of CTCs identified as KLF8⁺/vimentin⁺ (P < 0.01). Independent risk factors for recurrence were perineural invasion and > 50% KLF8⁺/vimentin⁺ CTCs (both P < 0.05).

CONCLUSION

Poor prognosis can be predicted in PC patients when > 50% of CTCs are positive for KLF8 and vimentin.

The Role of the IL-6 Cytokine Family in Epithelial-Mesenchymal Plasticity in Cancer Progression

Epithelial–mesenchymal plasticity (EMP) plays critical roles during embryonic development, wound repair, fibrosis, inflammation and cancer. During cancer progression, EMP results in heterogeneous and dynamic populations of cells with mixed epithelial and mesenchymal characteristics, which are required for local invasion and metastatic dissemination. Cancer development is associated with an inflammatory microenvironment characterized by the accumulation of multiple immune cells and pro-inflammatory mediators, such as cytokines and chemokines. Cytokines from the interleukin 6 (IL-6) family play fundamental roles in mediating tumour-promoting inflammation within the tumour microenvironment, and have been associated with chronic inflammation, autoimmunity, infectious diseases and cancer, where some members often act as diagnostic or prognostic biomarkers. All IL-6 family members signal through the Janus kinase (JAK)–signal transducer and activator of transcription (STAT) pathway and are able to activate a wide array of signalling pathways and transcription factors. In general, IL-6 cytokines activate EMP processes, fostering the acquisition of mesenchymal features in cancer cells. However, this effect may be highly context dependent. This review will summarise all the relevant literature related to all members of the IL-6 family and EMP, although it is mainly focused on IL-6 and oncostatin M (OSM), the family members that have been more extensively studied.

Zinc-Dependent Regulation of ZEB1 and YAP1 Coactivation Promotes Epithelial-Mesenchymal Transition Plasticity and Metastasis in Pancreatic Cancer

BACKGROUND

Pancreatic cancer is characterized by extensive metastasis. Epithelial-mesenchymal transition (EMT) plasticity plays a critical role in tumor progression and metastasis by maintaining the transition between EMT and mesenchymal-epithelial transition states. Our aim is to understand the molecular events regulating metastasis and EMT plasticity in pancreatic cancer.

METHODS

The interactions between a cancer-promoting zinc transporter ZIP4, a zinc-dependent EMT transcriptional factor ZEB1, a coactivator YAP1, and integrin α3 (ITGA3) were examined in human pancreatic cancer cells, clinical specimens, spontaneous mouse models (KPC and KPCZ) and orthotopic xenografts, and 3-dimensional spheroid and organoid models. Correlations between ZIP4, miR-373, and its downstream targets were assessed by RNA in situ hybridization and immunohistochemical staining. The transcriptional regulation of ZEB1, YAP1, and ITGA3 by ZIP4 was determined by chromatin immunoprecipitation, co-immunoprecipitation, and luciferase reporter assays.

RESULTS

The Hippo pathway effector YAP1 is a potent transcriptional coactivator and forms a complex with ZEB1 to activate ITGA3 transcription through the YAP1/transcriptional enhanced associate domain (TEAD) binding sites in human pancreatic cancer cells and KPC-derived mouse cells. ZIP4 upregulated YAP1 expression via activation of miR-373 and inhibition of the YAP1 repressor large tumor suppressor 2 kinase (LATS2). Furthermore, upregulation of ZIP4 promoted EMT plasticity, cell adhesion, spheroid formation, and organogenesis both in human pancreatic cancer cells, 3-dimensional spheroid model, xenograft model, and spontaneous mouse models (KPC and KPCZ) through ZEB1/YAP1-ITGA3 signaling axis.

CONCLUSION

We demonstrated that ZIP4 activates ZEB1 and YAP1 through distinct mechanisms. The ZIP4-miR-373-LATS2-ZEB1/YAP1-ITGA3 signaling axis has a significant impact on pancreatic cancer metastasis and EMT plasticity.

TGFβ signaling networks in ovarian cancer progression and plasticity

Epithelial ovarian cancer (EOC) is a leading cause of cancer-related death in women. Late-stage diagnosis with significant tumor burden, accompanied by recurrence and chemotherapy resistance, contributes to this poor prognosis. These morbidities are known to be tied to events associated with epithelial-mesenchymal transition (EMT) in cancer. During EMT, localized tumor cells alter their polarity, cell-cell junctions, cell-matrix interactions, acquire motility and invasiveness and an exaggerated potential for metastatic spread. Key triggers for EMT include the Transforming Growth Factor-β (TGFβ) family of growth factors which are actively produced by a wide array of cell types within a specific tumor and metastatic environment. Although TGFβ can act as either a tumor suppressor or promoter in cancer, TGFβ exhibits its pro-tumorigenic functions at least in part via EMT. TGFβ regulates EMT both at the transcriptional and post-transcriptional levels as outlined here. Despite recent advances in TGFβ based therapeutics, limited progress has been seen for ovarian cancers that are in much need of new therapeutic strategies. Here, we summarize and discuss several recent insights into the underlying signaling mechanisms of the TGFβ isoforms in EMT in the unique metastatic environment of EOCs and the current therapeutic interventions that may be relevant.

KRT6A Promotes EMT and Cancer Stem Cell Transformation in Lung Adenocarcinoma

Aim:

Keratin 6A is a type II cytokeratin which is important in forming nail bed, filiform papillae, the epithelial lining of oral mucosa, and esophagus; recently, keratin 6A was found hyperexpressed in different types of cancer. But, the biological function of keratin 6A in lung adenocarcinoma still remains unclear. Therefore, in current study, we investigated the biological role of keratin 6A in lung adenocarcinoma.

Methods:

By utilizing The Cancer Genome Atlas database, we investigated the expression profile of keratin 6A and its relationship with other clinical parameters in lung adenocarcinoma. The biological function of keratin 6A in lung adenocarcinoma was also investigated by using A549 and PC-9 lung cancer cell lines in vitro.

Results:

Our data indicate that, compared with normal lung tissue samples, keratin 6A was hyperexpressed in lung adenocarcinoma. Moreover, keratin 6A hyperexpression was positively correlated with lymph node positive and aggressive tumor T stage. Keratin 6A knockdown inhibited the cell proliferation, migration, and colony formation ability but not cell death in lung adenocarcinoma cells. In addition, we found keratin 6A exerted its phenotype via promoting cancer stem cells (CXCR4^high/CD133^high) transformation and epithelial–mesenchymal transition.

Conclusion:

In conclusion, current study suggests that hyperexpressed keratin 6A in lung adenocarcinoma promotes lung cancer proliferation and metastasis via epithelial–mesenchymal transition and cancer stem cells transformation.

Single-cell transcriptomics of human islet ontogeny defines the molecular basis of β-cell dedifferentiation in T2D

OBJECTIVE

Dedifferentiation of pancreatic β-cells may reduce islet function in type 2 diabetes (T2D). However, the prevalence, plasticity and functional consequences of this cellular state remain unknown.

METHODS

We employed single-cell RNAseq to detail the maturation program of α- and β-cells during human ontogeny. We also compared islets from non-diabetic and T2D individuals.

RESULTS

Both α- and β-cells mature in part by repressing non-endocrine genes; however, α-cells retain hallmarks of an immature state, while β-cells attain a full β-cell specific gene expression program. In islets from T2D donors, both α- and β-cells have a less mature expression profile, de-repressing the juvenile genetic program and exocrine genes and increasing expression of exocytosis, inflammation and stress response signalling pathways. These changes are consistent with the increased proportion of β-cells displaying suboptimal function observed in T2D islets.

CONCLUSIONS

These findings provide new insights into the molecular program underlying islet cell maturation during human ontogeny and the loss of transcriptomic maturity that occurs in islets of type 2 diabetics.

Gamabufotalin suppressed osteosarcoma stem cells through the TGF-β/periostin/PI3K/AKT pathway

AIMS

To investigate the effect of gamabufotalin (GBT) on metastasis and modulation of stemness features in osteosarcoma, and the molecular mechanisms underlying such effects.

METHODS

Human osteosarcoma U2OS/MG-63 cell lines were used in this study. Cell proliferation, migration, and invasion were determined by MTT assay, wound healing assay, and cell invasion assay, respectively. The inhibitive effect of GBT on stemness was assessed by flow cytometry and mammosphere formation. The protein levels of related proteins were detected by western blotting analysis. The effect of GBT on tumorigenicity and metastasis was determined by immunofluorescence staining and immunohistochemistry in vivo experiments.

RESULTS

We found that GBT suppressed the viability of U2OS/MG-63 cells in a time- and dose-dependent manner. Notably, GBT had no effect on the viability of human fetal osteoblastic (hFOB) 1.19 cells. Moreover, GBT increased the width of wounds, reduced the number of invasive osteosarcoma cells and reversed the epithelial-mesenchymal transition phenotype. Notably, we found that, compared with hFOB1.19 cells, the levels of transforming growth factor-β (TGF-β), periostin, phosphorylated-AKT (p-AKT), and phosphorylated-PI3K (p-PI3K) were higher in spheroids group than in parent cells. In addition, GBT reduced the ratio of CD133+ cells, the size of spheroids and Nanog, as well as the protein levels of SRY-box transcription factor 2 (SOX2), and octamer-binding protein 3/4 (OCT3/4). Our in vivo experiments showed that GBT consistently reduced lung metastasis lesions, the expression levels of matrix metalloproteinase 2 (MMP2), TGF-β, periostin, p-AKT, and p-PI3K (immunohistochemistry staining), as well as that of CD133 in tumor tissues (immunofluorescence analysis). From a mechanistic point of view, exogenous TGF-β/periostin/PI3K/AKT overexpression neutralized the reduction of GBT-decreased invasion/migration and the suppression of stemness properties.

CONCLUSION

Collectively, our data demonstrated that GBT inhibited the viability and tumorigenesis capability of osteosarcoma cells by blocking the TGF-β/periostin/PI3K/AKT signaling pathway. Therefore, GBT may represent a promising therapeutic agent for the management of osteosarcoma.

Intrinsic Balance between ZEB Family Members Is Important for Melanocyte Homeostasis and Melanoma Progression

It has become clear that cellular plasticity is a main driver of cancer therapy resistance. Consequently, there is a need to mechanistically identify the factors driving this process. The transcription factors of the zinc-finger E-box-binding homeobox family, consisting of ZEB1 and ZEB2, are notorious for their roles in epithelial-to-mesenchymal transition (EMT). However, in melanoma, an intrinsic balance between ZEB1 and ZEB2 seems to determine the cellular state by modulating the expression of the master regulator of melanocyte homeostasis, microphthalmia-associated transcription factor (MITF). ZEB2 drives MITF expression and is associated with a differentiated/proliferative melanoma cell state. On the other hand, ZEB1 is correlated with low MITF expression and a more invasive, stem cell-like and therapy-resistant cell state. This intrinsic balance between ZEB1 and ZEB2 could prove to be a promising therapeutic target for melanoma patients. In this review, we will summarise what is known on the functional mechanisms of these transcription factors. Moreover, we will look specifically at their roles during melanocyte-lineage development and homeostasis. Finally, we will overview the current literature on ZEB1 and ZEB2 in the melanoma context and link this to the 'phenotype-switching' model of melanoma cellular plasticity.

Clinical implications of cancer stem cells in digestive cancers: acquisition of stemness and prognostic impact

Digestive system cancers are the most frequent cancers worldwide and often associated with poor prognosis because of their invasive and metastatic characteristics. Recent studies have found that the plasticity of cancer cells can impart cancer stem-like properties via the epithelial-mesenchymal transition (EMT). Cancer stem-like properties such as tumor initiation are integral to the formation of metastasis, which is the main cause of poor prognosis. Numerous markers of cancer stem cells (CSCs) have been identified in many types of cancer. Therefore, CSCs, via their stem cell-like functions, may play an important role in prognosis after surgery. While several reports have described prognostic analysis using CSC markers, few reviews have summarized CSCs and their association with prognosis. Herein, we review the prognostic potential of eight CSC markers, CD133, CD44, CD90, ALDH1A1, EPCAM, SOX2, SOX9, and LGR5, in digestive cancers including those of the pancreas, colon, liver, gastric, and esophagus.