CD24 can be used to isolate Lgr5+ putative colonic epithelial stem cells in mice

Prenatal stress induces changes in PAR2- and M3-dependent regulation of colon primitive cells

Prenatal stress is associated with a high risk of developing adult intestinal pathologies, such as irritable bowel syndrome, chronic inflammation, and cancer. Although epithelial stem cells and progenitors have been implicated in intestinal pathophysiology, how prenatal stress could impact their functions is still unknown. We have investigated the proliferative and differentiation capacities of primitive cells using epithelial crypts isolated from colons of adult male and female mice whose mothers have been stressed during late gestation. Our results show that stem cell/progenitor proliferation and differentiation in vitro are negatively impacted by prenatal stress in male progeny. This is promoted by a reinforcement of the negative proliferative/differentiation control by the protease-activated receptor 2 (PAR2) and the muscarinic receptor 3 (M3), two G protein-coupled receptors present in the crypt. Conversely, prenatal stress does not change in vitro proliferation of colon primitive cells in female progeny. Importantly, this maintenance is associated with a functional switch in the M3 negative control of colonoid growth, becoming proliferative after prenatal stress. In addition, the proliferative role of PAR2 specific to females is maintained under prenatal stress, even though PAR2-targeted stress signals Dusp6 and activated GSK3β are increased, reaching the levels of males. An epithelial serine protease could play a critical role in the activation of the survival kinase GSK3β in colonoids from prenatally stressed female progeny. Altogether, our results show that following prenatal stress, colon primitive cells cope with stress through sexually dimorphic mechanisms that could pave the way to dysregulated crypt regeneration and intestinal pathologies.NEW & NOTEWORTHY Primitive cells isolated from mouse colon following prenatal stress and exposed to additional stress conditions such as in vitro culture, present sexually dimorphic mechanisms based on PAR2- and M3-dependent regulation of proliferation and differentiation. Whereas prenatal stress reinforces the physiological negative control exerted by PAR2 and M3 in crypts from males, in females, it induces a switch in M3- and PAR2-dependent regulation leading to a resistant and proliferative phenotype of progenitor.

Tumor collection/processing under physioxia uncovers highly relevant signaling networks and drug sensitivity

Preclinical studies of primary cancer cells are typically done after tumors are removed from patients or animals at ambient atmospheric oxygen (O2, ~21%). However, O2 concentrations in organs are in the ~3 to 10% range, with most tumors in a hypoxic or 1 to 2% O2 environment in vivo. Although effects of O2 tension on tumor cell characteristics in vitro have been studied, these studies are done only after tumors are first collected and processed in ambient air. Similarly, sensitivity of primary cancer cells to anticancer agents is routinely examined at ambient O2. Here, we demonstrate that tumors collected, processed, and propagated at physiologic O2 compared to ambient air display distinct differences in key signaling networks including LGR5/WNT, YAP, and NRF2/KEAP1, nuclear reactive oxygen species, alternative splicing, and sensitivity to targeted therapies. Therefore, evaluating cancer cells under physioxia could more closely recapitulate their physiopathologic status in the in vivo microenvironment.

Colon Crypts of Subjects With Familial Adenomatous Polyposis Show an Increased Number of LGR5+ Ectopic Stem Cells

INTRODUCTION

Familial adenomatous polyposis (FAP) is a hereditary colorectal cancer (CRC) syndrome characterized by accelerated adenoma development due to inherited (or de novo) mutations in the APC regulator of WNT signaling pathway (APC) gene. The mechanism underlying this accelerated polyp development in subjects with FAP has not been defined. Given that LGR5+ stem cells drive crypt cell proliferation, we hypothesized that FAP crypts would demonstrate aberrant leucine-rich repeat-containing G-protein-coupled receptor 5 (LGR5) staining patterns.

METHODS

Biopsies were taken from 11 healthy subjects, 7 subjects with Lynch syndrome, 4 subjects with FAP, and 1 subject with MUTYH-associated polyposis syndrome during routine screening or surveillance colonoscopy. Crypt staining was evaluated by immunohistochemistry of paraffin-embedded tissue sections. Stem cell numbers were estimated by immunofluorescence staining of isolated crypts using antibodies against LGR5 and other proteins.

RESULTS

Subjects with FAP exhibited a greater number of LGR5+ stem cells in their crypts than healthy subjects and subjects with Lynch syndrome and MUTYH-associated polyposis syndrome. Most crypts of subjects with FAP harbored LGR5+ cells located above the lower third of the crypts.

DISCUSSION

These findings support a model in which inactivation of one copy of APC leads to increased numbers of LGR5+ stem cells, many of which are ectopic, in colon crypts of subjects with FAP. Overabundant and ectopic LGR5+ stem cells could lead to an expanded proliferative zone of dividing cells more likely to develop mutations that would contribute to the accelerated adenoma development observed in FAP.

Blood Circulating Exosomes Contain Distinguishable Fractions of Free and Cell-Surface-Associated Vesicles

BACKGROUND

Considering exosomes as intercellular transporters, inevitably interacting with the plasma membrane and the large available surface of blood cells, we wonder if a fraction of circulating exosomes is associated with the surface of blood cells.

OBJECTIVE

The aim of this study was to develop an efficient protocol for isolating exosomes associated with the surface of blood cells and to further investigate the characteristics of this fraction in a healthy state and during the development of breast cancer, as well as its possible implication for use in diagnostic applications.

METHODS

Blood samples were collected from Healthy Females (HFs) and breast cancer patients (BCPs). Exosomes extracted from blood plasma and eluted from the surface of blood cells were isolated by ultrafiltration with subsequent ultracentrifugation.

RESULTS

Transmission Electron Microscopy (TEM), along with immunogold labeling, demonstrated the presence of exosomes among membrane-wrapped extracellular vesicles (EVs) isolated from both plasma and blood cell eluates. TEM, nanoparticle tracking analysis, and NanoOrange protein quantitation data showed that cell-associated exosomes constituted no less than 2/3 of total blood exosome number. Exosomes, ranging from 50-70 nm in size, prevailed in the blood of breast cancer patients, whereas smaller exosomes (30-50 nm) were mostly observed in the blood of healthy women. Analysis of specific proteins and RNAs in exosomes circulating in blood demonstrated the significant differences in the packing density of the polymers in exosomes of HFs and BCPs. Preliminary data indicated that detection of cancer-specific miRNA (miR-103, miR-191, miR-195) in exosomes associated with the fraction of red blood cells allowed to discriminate HFs and BCPs more precisely compared to cell-free exosomes circulating in plasma.

CONCLUSION

Our data provide the basis for using blood cell-associated exosomes for diagnostic applications.

Proteomic Analysis of Blood Exosomes from Healthy Females and Breast Cancer Patients Reveals an Association between Different Exosomal Bioactivity on Non-tumorigenic Epithelial Cell and Breast Cancer Cell Migration in Vitro

Exosomes are important intercellular communication vehicles, secreted into body fluids by multiple cell types, including tumor cells. They contribute to the metastatic progression of tumor cells through paracrine signalling. It has been recently discovered that blood circulating exosomes contain distinguishable fractions of free and cell-surface-associated vesicles. We evaluated the influence of protein cargoes from exosomes from plasma, and exosomes from the total blood of healthy females (HFs) and breast cancer patients (BCPs), on cell motility. We conducted a mass spectrometric analysis of exosomal contents isolated from samples using ultrafiltration and ultracentrifugation approaches and verified their nature using transmission electron microscopy, nanoparticle tracking analysis and flow cytometry. We observed that malignant neoplasm-associated proteins in exosomes from BCP total blood were detected more often than in plasma (66% vs. 59%). FunRich analysis to assess Gene Ontology (GO) enrichment revealed that proteins with catalytic activities, transporter functions and protein metabolism activities were increased in exosomes from BCP blood. Finally, GO analysis revealed that proteomic profiles of exosomes from HF total blood were enriched with proteins inhibiting cell migration and invasion, which explains the low stimulating activity of exosomes from HF total blood on SKBR-3 cancer cell migration velocity. This allows exosomes to act as intermediaries providing intercellular communications through horizontal transfer of RNA and functionally active proteins, potentially affecting the development of both primary neoplasms and distant metastases.

Intracellular DNA replication and differentiation of Trypanosoma cruzi is asynchronous within individual host cells in vivo at all stages of infection

Investigations into intracellular replication and differentiation of Trypanosoma cruzi within the mammalian host have been restricted by limitations in our ability to detect parasitized cells throughout the course of infection. We have overcome this problem by generating genetically modified parasites that express a bioluminescent/fluorescent fusion protein. By combining in vivo imaging and confocal microscopy, this has enabled us to routinely visualise murine infections at the level of individual host cells. These studies reveal that intracellular parasite replication is an asynchronous process, irrespective of tissue location or disease stage. Furthermore, using TUNEL assays and EdU labelling, we demonstrate that within individual infected cells, replication of both mitochondrial (kDNA) and nuclear genomes is not co-ordinated within the parasite population, and that replicating amastigotes and non-replicating trypomastigotes can co-exist in the same cell. Finally, we report the presence of distinct non-canonical morphological forms of T. cruzi in the mammalian host. These appear to represent transitional forms in the amastigote to trypomastigote differentiation process. Therefore, the intracellular life-cycle of T. cruzi in vivo is more complex than previously realised, with potential implications for our understanding of disease pathogenesis, immune evasion and drug development. Dissecting the mechanisms involved will be an important experimental challenge.

Chagas disease, caused by the protozoan parasite Trypanosoma cruzi, is becoming an emerging threat in non-endemic countries and establishing new foci in endemic countries. The treatment available has not changed significantly in over 40 years. Therefore, there is an urgent need for a greater understanding of parasite biology and disease pathogenesis to identify new therapeutic targets and to maximise the efficient use of existing drugs. We have used genetically modified strains of T. cruzi carrying a bioluminescence/fluorescence dual reporter fusion gene to monitor parasite replication in vivo during both acute and chronic infections in a mouse model. Utilising TUNEL assays for mitochondrial DNA replication and EdU incorporation for total DNA replication, we have found that parasite division within infected cells is asynchronous in all phases of infection. Differentiation also appears to be uncoordinated, with replicating amastigotes co-existing with non-dividing trypomastigotes in the same host cell.

Isolation and characterization of breast cancer stem cell-like phenotype by Oct4 promoter-mediated activity

Cancer stem cells (CSCs) are a small subset of cancer cells responsible for self-renewal activity, drug resistance, and tumor recurrence. CSCs have been derived from diverse tumors and cell lines. The expression of stemness markers has been identified in CSCs. Oct4 is a well-established transcription factor expressed in stem cells and CSCs. In this study, we isolated and characterized breast CSC-like cells from murine MC4-L2 cells by Oct4 promoter-mediated activity. The MC4-L2 cells were electroporated by a plasmid expressing puromycin resistance (Puro^R ) gene from the Oct4 promoter and then selected by puromycin. The isolated cells were named as the MC4-L2^puro cells and characterized for CSCs properties. Immunostaining indicated CD44^high and CD24^high phenotype for the MC4-L2 and MC4-L2^puro cells. The enhanced expression of stem cell markers was detected in the puromycin-selected cells compared with the parental cells. Moreover, the isolated cells only grew up in sphere-formed shape in low attachment plates. Serial dilution transplantation in syngeneic mouse models showed increased tumorigenicity of the MC4-L2^puro cells, as they induced new tumors when injected into the mammary fat pad as few as 10⁴ cells. In conclusion, we designed a novel genetic construct, which allows the isolation of Oct4-positive cells in a cancer population by a simple selection step in a puromycin-containing medium. Transfection of this construct into the MC4-L2 cells resulted in growing a subpopulation of cells having tumor-initiating cell characteristics. To the best of our knowledge, this is the first report on the isolation of CSC-like cells from the mouse breast cancer MC4-L2 cells.

Induction of Nitric-Oxide Metabolism in Enterocytes Alleviates Colitis and Inflammation-Associated Colon Cancer

Nitric oxide (NO) plays an established role in numerous physiological and pathological processes, but the specific cellular sources of NO in disease pathogenesis remain unclear, preventing the implementation of NO-related therapy. Argininosuccinate lyase (ASL) is the only enzyme able to produce arginine, the substrate for NO generation by nitric oxide synthase (NOS) isoforms. Here, we generated cell-specific conditional ASL knockout mice in combination with genetic and chemical colitis models. We demonstrate that NO derived from enterocytes alleviates colitis by decreasing macrophage infiltration and tissue damage, whereas immune cell-derived NO is associated with macrophage activation, resulting in increased severity of inflammation. We find that induction of endogenous NO production by enterocytes with supplements that upregulate ASL expression and complement its substrates results in improved epithelial integrity and alleviation of colitis and of inflammation-associated colon cancer.

Sexual dimorphism in PAR2-dependent regulation of primitive colonic cells

BACKGROUND

Sexual dimorphism in biological responses is a critical knowledge for therapeutic proposals. However, gender differences in intestinal stem cell physiology have been poorly studied. Given the important role of the protease-activated receptor PAR₂ in the control of colon epithelial primitive cells and cell cycle genes, we have performed a sex-based comparison of its expression and of the effects of PAR₂ activation or knockout on cell proliferation and survival functions.

METHODS

Epithelial primitive cells isolated from colons from male and female mice were cultured as colonoids, and their number and size were measured. PAR₂ activation was triggered by the addition of SLIGRL agonist peptide in the culture medium. PAR₂-deficient mice were used to study the impact of PAR₂ expression on colon epithelial cell culture and gene expression.

RESULTS

Colonoids from female mice were more abundant and larger compared to males, and these differences were further increased after PAR₂ activation by specific PAR₂ agonist peptide. The proliferation of male epithelial cells was lower compared to females but was specifically increased in PAR₂ knockout male cells. PAR₂ expression was higher in male colon cells compared to females and controlled the gene expression and activation of key negative signals of the primitive cell proliferation. This PAR₂-dependent brake on the proliferation of male colon primitive cells was correlated with stress resistance.

CONCLUSIONS

Altogether, these data demonstrate that there is a sexual dimorphism in the PAR₂-dependent regulation of primitive cells of the colon crypt.

What information can be obtained from the tears of a patient with primary open angle glaucoma?

Since tears are a biological fluid, they have a potential diagnostic value for ophthalmic diseases. The aim of this study was to compare tear supernatants and pellets obtained from patients suffering from primary open angle glaucoma (POAG) and healthy persons (HPs) using transmission electron microscopy (TEM) and molecular biological methods. Tear supernatants and pellets were prepared using ultrafiltration and ultracentrifugation and were examined by negative staining and immunogold labelling TEM. DNA of the pellets was isolated, quantified and sequenced using a MiSeq (Illumina, USA) genomic sequencer with the Reagent Kit v3 (600 cycles, Illumina, USA). MicroRNA was isolated and quantified from the pellets; miR-146b, miR-16 and miR-126 were detected using TaqMan MicroRNA Assays (Applied Biosystems, USA). TEM of tear supernatants from both POAG patients and HPs revealed identical constituents: spherical or cup-shaped vesicles, "non-vesicles", cell debris and macromolecular aggregates. Pellets of POAG patients and HPs contained small extracellular vesicles (sEVs) non-labelled vesicles and "non-vesicles"; pellets of sick persons also contained sEVs with "a capsule". POAG-patient tear pellets showed elevated concentrations of genomic ds-DNA and SINE-repeats, and different expressions of miR-146b, miR-16 and miR-126 and a different set of bacterial DNA in comparison with pellets obtained from the tears of HPs. The data obtained indicate that the tears of HPs and POAG patients could serve as an object for TEM studies and as a source of sEV-containing preparations (pellets), which, in turn, could be used for the isolation and study of genomic ds-DNA and RNA. Our data provide the basis for using tears for diagnostic applications.

miR-372 and miR-373 enhance the stemness of colorectal cancer cells by repressing differentiation signaling pathways

miR‐372/373, a cluster of stem cell‐specific microRNAs transactivated by the Wnt pathway, has been reported to be dysregulated in various cancers, particularly colorectal cancer (CRC); however, the unique role of these microRNAs in cancer remains to be discovered. In the present study, we characterized the upregulation in expression of miR‐372/373 in CRC tissues from The Cancer Genome Atlas data, and then showed that overexpression of miR‐372/373 enhanced the stemness of CRC cells by enriching the CD26/CD24‐positive cell population and promoting self‐renewal, chemotherapy resistance and the invasive potential of CRC cells. To clarify the mechanism underlying microRNA‐induced stemness, we profiled 45 cell signaling pathways in CRC cells overexpressing miR‐372/373 and found that stemness‐related pathways, such as Nanog and Hedgehog, were upregulated. Instead, differentiation‐related pathways, such as NFκB, MAPK/Erk and VDR, were markedly repressed by miR‐372/373. Numerous new targets of miR‐372/373 were identified, including SPOP, VDR and SETD7, all of which are factors important for cell differentiation. Furthermore, in contrast to the increase in miR‐372/373 expression in CRC tissues, the expression levels of SPOP and VDR mRNA were significantly downregulated in these tissues, indicative of the poor differentiation status of CRC. Taken together, our findings suggest that miR‐372/373 enhance CRC cell stemness by repressing the expression of differentiation genes. These results provide new insights for understanding the function and mechanisms of stem cell‐specific microRNAs in the development of metastasis and drug resistance in CRC.

Transcriptomic but not genomic variability confers phenotype of breast cancer stem cells

Background

Breast cancer stem cells (BCSCs) are considered responsible for cancer relapse and drug resistance. Understanding the identity of BCSCs may open new avenues in breast cancer therapy. Although several discoveries have been made on BCSC characterization, the factors critical to the origination of BCSCs are largely unclear. This study aimed to determine whether genomic mutations contribute to the acquisition of cancer stem-like phenotype and to investigate the genetic and transcriptional features of BCSCs.

Methods

We detected potential BCSC phenotype-associated mutation hotspot regions by using whole-genome sequencing on parental cancer cells and derived serial-generation spheres in increasing order of BCSC frequency, and then performed target deep DNA sequencing at bulk-cell and single-cell levels. To identify the transcriptional program associated with BCSCs, bulk-cell and single-cell RNA sequencing was performed.

Results

By using whole-genome sequencing of bulk cells, potential BCSC phenotype-associated mutation hotspot regions were detected. Validation by target deep DNA sequencing, at both bulk-cell and single-cell levels, revealed no genetic changes specifically associated with BCSC phenotype. Moreover, single-cell RNA sequencing showed profound transcriptomic variability in cancer cells at the single-cell level that predicted BCSC features. Notably, this transcriptomic variability was enriched during the transcription of 74 genes, revealed as BCSC markers. Breast cancer patients with a high risk of relapse exhibited higher expression levels of these BCSC markers than those with a low risk of relapse, thereby highlighting the clinical significance of predicting breast cancer prognosis with these BCSC markers.

Conclusions

Transcriptomic variability, not genetic mutations, distinguishes BCSCs from non-BCSCs. The identified 74 BCSC markers have the potential of becoming novel targets for breast cancer therapy.

Electronic supplementary material

The online version of this article (10.1186/s40880-018-0326-8) contains supplementary material, which is available to authorized users.

Wnt Effector TCF4 Is Dispensable for Wnt Signaling in Human Cancer Cells

T-cell factor 4 (TCF4), together with β-catenin coactivator, functions as the major transcriptional mediator of the canonical wingless/integrated (Wnt) signaling pathway in the intestinal epithelium. The pathway activity is essential for both intestinal homeostasis and tumorigenesis. To date, several mouse models and cellular systems have been used to analyze TCF4 function. However, some findings were conflicting, especially those that were related to the defects observed in the mouse gastrointestinal tract after Tcf4 gene deletion, or to a potential tumor suppressive role of the gene in intestinal cancer cells or tumors. Here, we present the results obtained using a newly generated conditional Tcf4 allele that allows inactivation of all potential Tcf4 isoforms in the mouse tissue or small intestinal and colon organoids. We also employed the clustered regularly interspaced short palindromic repeats (CRISPR)/Cas9 system to disrupt the TCF4 gene in human cells. We showed that in adult mice, epithelial expression of Tcf4 is indispensable for cell proliferation and tumor initiation. However, in human cells, the TCF4 role is redundant with the related T-cell factor 1 (TCF1) and lymphoid enhancer-binding factor 1 (LEF1) transcription factors.

Colon organoid formation and cryptogenesis are stimulated by growth factors secreted from myofibroblasts

Although small intestinal epithelial stem cells form crypts when using intestinal culture conditions, colon stem cells usually form colonospheres. Colon mesenchymal cell feeder layers can stimulate colon crypts to form organoids and produce crypts. We have investigated whether conditioned medium from colon mesenchymal cells can also stimulate colonosphere and organoid cryptogenesis. We prepared conditioned medium (CM) from WEHI-YH2 cells (mouse colon myofibroblasts); the CM stimulated both colonosphere formation and organoid cryptogenesis in vitro. The colon organoid-stimulating factors in WEHI-YH2 CM are inactivated by heating and trypsin digestion and proteins can be concentrated by ultrafiltration. Both the colonosphere- and organoid cryptogenesis- stimulatory effects of the CM are independent of canonical Wnt and Notch signaling. In contrast, bone morphogenetic protein 4 (BMP4) abolishes colonosphere formation and organoid cryptogenesis. The Transforming Growth Factor beta (TGFβ) Type I receptor kinase inhibitor (A83-01) stimulates colonosphere formation, whereas the Epidermal Growth Factor receptor (EGFR) kinase inhibitor (AG1478) reduces the formation of colonospheres, but in the presence of EGF, a “just-right” concentration of AG1478 increases colon organoid cryptogenesis.

[Comparative sub-population analysis of exosomes from blood plasma of cancer patients]

To increase the sensitivity and specificity of the developed methods for diagnosis of oncological diseases using exosomes of blood, a stage of pre-selection of tumor exosomes from a common pool of circulating microvesicles is required. In the present work, universal proteins have been identified, their expression has been increased in the exosomes of patients with colorectal cancer, head and neck squamous cell carcinomas, and lung cancer. The use of antibodies against major exosomal proteins will further develop a simple and high-performance method of affinity isolation of tumor exosomes.

Expression of CD24 and B7-H3 in breast cancer and the clinical significance

This study aimed to investigate the correlation between the expression of CD24 and B7-H3 in breast cancer tissues and the clinical significance. Expression of CD24 and B7-H3 in breast cancer and adjacent tissues were detected by immunohistochemistry. Quantitative PCR was used to detect the expression of CD24 and B7-H3 mRNA in breast cancer and adjacent tissues. The expression of CD24 and B7-H3 protein in breast cancer and adjacent tissues was detected by immunoblotting. The correlation between the expression levels of the two proteins was analyzed and the relationship between the expression of two proteins and the 5-year survival of breast cancer patients was investigated. CD24 and B7-H3 were positively expressed in breast cancer and adjacent tissues, the CD24-positive rate was 75.7 and 25.7%, respectively, and the B7-H3-positive rate was 56.8 and 43.2%, respectively, and the differences were statistically significant (P<0.05). The expression of CD24 was positively correlated with the expression of B7-H3 (Spearman's correlation coefficient r, 0.297; p=0.036). The positive and negative expression of CD24 and B7-H3 significantly affected the 5-year survival of breast cancer patients (P<0.05). Quantitative PCR results showed that the expression levels of CD24 and B7-H3 mRNA in breast cancer tissues were significantly higher than those in adjacent tissues (P<0.05). The expression levels of CD24 and B7-H3 protein in breast cancer tissues were also significantly higher than those in adjacent tissues (P<0.05). CD24 and B7-H3 were highly expressed in breast cancer, suggesting that both CD24 and B7-H3 were related to the development of breast cancer. Five-year survival analysis of breast cancer patients showed that the high expression of CD24 and B7-H3 were correlated with the poor prognosis of patients. Thus, CD24 and B7-H3 may become new targets for the treatment of breast cancer.

[Isolation and characterization of exosomes from blood plasma of breast cancer and colorectal cancer patients]

A simple approach for isolation of exosomes from the blood plasma, which allows to obtain highly purified preparations of microvesicles no larger than 100 nm has been proposed. The presence of different subpopulations of exosomes in the blood plasma of healthy donors and cancer patients has been recognized. We found the presence of the universal markers CD9, CD24 and CD81 on exosomes isolated from blood plasma that can be used to their routine typing.

CD24 expression is a marker for predicting clinical outcome and regulates the epithelial-mesenchymal transition in ovarian cancer via both the Akt and ERK pathways

The degree of peritoneal dissemination and chemotherapy-resistant tumors is related to the prognosis in patients with advanced-stage ovarian cancer. The epithelial-mesenchymal-transition (EMT) is a multifaceted pathological program that endows cancer cells with the ability to invade and disseminate. CD24 is frequently overexpressed in various human cancers and is correlated with a poor prognosis. We herein examined the functions of CD24 in human ovarian cancer cell lines and evaluated how it contributes to the molecular mechanism underlying the regeneration of cancer stem-like cells (CSCs) through the EMT mechanism in ovarian carcinoma. We demonstrated that CD24 was expressed in 70.1% of primary ovarian carcinoma tissues, which were obtained from 174 patients, and that the expression of CD24 was an independent predictor of survival in patients with ovarian cancer. The expression of CD24 has been found to be correlated with the FIGO stage, presence of peritoneal and lymph node metastasis. CD24 induces the EMT phenomenon, which is involved in cell invasion, the highly proliferative phenotype, colony formation and which is associated with cisplatin resistance and the properties of CSCs, via the activation of PI3K/Akt, NF-κB and ERK in Caov-3 cisplatin-resistant cell lines. CD24-positive ovarian carcinomas have been shown to have a greater potential for intra-abdominal tumor cell dissemination in in vivo models. Our findings suggest that CD24 induced the EMT phenomenon in ovarian cancer, and that CD24 amplified cell growth-related intracellular signaling via the PI3K/Akt and MAPK pathways by affecting the EMT signal pathways. We believe that CD24 is a key molecule of metastatic progression in the EMT phenomenon and a promising therapeutic target for advanced ovarian cancer.

Comparative Study of Extracellular Vesicles from the Urine of Healthy Individuals and Prostate Cancer Patients. PLoS One. 2016;11:e0157566. [PMID: 27305142 PMCID: PMC4909321 DOI: 10.1371/journal.pone.0157566]

Recent studies suggest that extracellular vesicles may be the key to timely diagnosis and monitoring of genito-urological malignancies. In this study we investigated the composition and content of extracellular vesicles found in the urine of healthy donors and prostate cancer patients. Urine of 14 PCa patients and 20 healthy volunteers was clarified by low-speed centrifugation and total extracellular vesicles fraction was obtain by high-speed centrifugation. The exosome-enriched fraction was obtained by filtration of total extracellular vesicles through a 0.1 μm pore filter. Transmission electron microscopy showed that cell-free urine in both groups contained vesicles from 20 to 230 nm. Immunogold staining after ultrafiltration demonstrated that 95% and 90% of extracellular vesicles in healthy individuals and cancer patients, respectively, were exosomes. Protein, DNA and RNA concentrations as well as size distribution of extracellular vesicles in both fractions were analyzed. Only 75% of the total protein content of extracellular vesicles was associated with exosomes which amounted to 90–95% of all vesicles. Median DNA concentrations in total extracellular vesicles and exosome-enriched fractions were 18 pg/ml and 2.6 pg/ml urine, correspondingly. Urine extracellular vesicles carried a population of RNA molecules 25 nt to 200 nt in concentration of no more than 290 pg/ml of urine. Additionally, concentrations of miR-19b, miR-25, miR-125b, and miR-205 were quantified by qRT-PCR. MiRNAs were shown to be differently distributed between different fractions of extracellular vesicles. Detection of miR-19b versus miR-16 in total vesicles and exosome-enriched fractions achieved 100%/93% and 95%/79% specificity/sensitivity in distinguishing cancer patients from healthy individuals, respectively, demonstrating the diagnostic value of urine extracellular vesicles.

A Versatile Strategy for Isolating a Highly Enriched Population of Intestinal Stem Cells

The isolation of pure populations of mouse intestinal stem cells (ISCs) is essential to facilitate functional studies of tissue homeostasis, tissue regeneration, and intestinal diseases. However, the purification of ISCs has relied predominantly on the use of transgenic reporter alleles in mice. Here, we introduce a combinational cell surface marker-mediated strategy that allows the isolation of an ISC population transcriptionally and functionally equivalent to the gold standard Lgr5-GFP ISCs. Used on reporter-free mice, this strategy allows the isolation of functional, transcriptionally distinct ISCs uncompromised by Lgr5 haploinsufficiency.

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Reporter-free method to purify intestinal stem cells (ISCs)

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Cells share molecular signature with gold standard Lgr5-GFP high cells

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Multidimensional FACS data analysis reveals structure of intestinal crypt

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Lgr5 haploinsufficiency with functional consequences in ISCs from reporter mice

CD24 associates with EGFR and supports EGF/EGFR signaling via RhoA in gastric cancer cells

Background

CD24, a mucin-like membrane glycoprotein, plays a critical role in carcinogenesis, but its role in human gastric cancer and the underlying mechanism remains undefined.

Methods

The contents of CD24 and epidermal growth factor receptor (EGFR) in gastric cancer cells (SGC-7901 and BGC-823) and non-malignant gastric epithelial cells (GES-1) were evaluated by Western blotting assay. Cellular EGFR staining was examined by immunofluorescence assay. Cell migration rate was measured by wound healing assay. The effects of depletion/overexperssion of CD24 on EGFR expression and activation of EGF/EGFR singaling pathways were evaluated by immunofluorescence, qPCR, Western blotting and flow cytometry techniques. RhoA activity was assessed by pulldown assay. CD24 and EGFR expression patterns in human gastric tumor samples were also investigated by immunohistochemistry staining.

Results

CD24 was overexpressed in human gastric cancer cells. Ectopic expression of CD24 in gastric epithelial cells augmented the expression of EGFR, while knockdown of CD24 in gastric cancer cells decreased the level of EGFR and cell migration velocity. To further explore the mechanisms, we investigated the effect of CD24 expression on EGF/EGFR signaling. We noticed that this effect of CD24 on EGFR expression was dependent on promoting EGFR internalization and degradation. Lower ERK and Akt phosphorylations in response to EGF stimulation were observed in CD24-depleted cells. In addition, we noticed that the effect of CD24 on EGFR stability was mediated by RhoA activity in SGC-7901 gastric cancer cells. Analysis of gastric cancer specimens revealed a positive correlation between CD24 and EGFR levels and an association between CD24 expression and worse prognosis.

Conclusion

Thus, these findings suggest for the first time that CD24 regulates EGFR signaling by inhibiting EGFR internalization and degradation in a RhoA-dependent manner in gastric cancer cells.

Electronic supplementary material

The online version of this article (doi:10.1186/s12967-016-0787-y) contains supplementary material, which is available to authorized users.

Characteristics of exosomes andmicroparticles discovered in human tears

Exosomes represent a sort of extracellular vesicles, which transfer molecular signals in organism and possess markers of producing cells. Our study was aimed at search of exosomes in the tears of healthy humans, confirmation of their nature and examination of exosome morphological and molecular-biological characteristics. The tears (110-340 ml) were collected from 24 healthy donors (aged 46-60 years); individual probes were centrifuged at 20000 g for 15 min to pellet cell debris. The supernatants were examined in electron microscope using negative staining; and they were also used for isolation and purification of the exosomes by filtration (100 nm pore-size) and double ultracentrifugation (90 min at 100000 g, 4°C). The “pellets” were subjected to electron microscopy, immunolabeling. The RNA and DNA were isolated from the samples, and their sizes were evaluated by capillary electrophoresis, the concentration and localization of nucleic acids were determined. Sequencing of DNA was performed using MiSeq (“Illumina”, USA), data were analyzed using CLC GW 7.5 (“Qiagen”, USA). Sequences were mapped on human genome (hg19). Electron microscopy revealed in supernatants of the tears cell debris, spherical microparticles (20-40 nm), membrane vesicles and macromolecular aggregates. The “pellets” obtained after ultracentrifugation, contained microparticles (17%), spherical and cup-shaped EVs (40-100 nm, 83%), which were positive for CD63, CD9 and CD24 receptors (specific markers of exosomes). Our study showed presence of high amount of exosomes in human tears, and relation of the exosomes with RNA (size less than 200 nt) and DNA (size was 3-9 kb). Sequencing of the DNA showed that about 92% of the reads mapped to human genome.

Epigenetic and Immune Regulation of Colorectal Cancer Stem Cells

Colorectal cancer stem cells (CSCs) were initially considered to be a subset of undifferentiated tumor cells with well-defined phenotypic and molecular markers. However, emerging evidence indicates instead that colorectal CSCs are heterogeneous subsets of tumor cells that are continuously reshaped by the dynamic interactions between genetic, epigenetic, and immune factors in the tumor microenvironment. Thus, the colorectal CSC phenotypes and responsiveness to therapy may not only be a tumor cell-intrinsic feature, but also depend on tumor-extrinsic microenvironmental factors. Furthermore, emerging evidence also implicates colorectal CSCs in potential immune evasion. Therefore, understanding how colorectal CSC-intrinsic mechanisms cooperate with the extrinsic microenvironmental factors to dynamically shape colorectal CSC resistance to chemotherapy and immunotherapy holds great promise for development of targeted CSC therapies of advanced human CRC.

CD24 expression as a marker for predicting clinical outcome and invasive activity in uterine cervical cancer

CD24, a small heavily glycosylated mucin-like glycosylphosphatidylinositol-anchored cell surface protein, plays an important role in the carcinogenesis of various human malignancies. However, its function in cervical cancer remains unclear. The aim of the present study was to evaluate the expression of CD24 clinicopathologically and to analyze its functional behavior biologically in cervical cancer. A total of 117 uterine cervical cancer tumors were immunohistochemically analyzed using a CD24 monoclonal antibody on paraffin blocks. We also examined whether CD24 enhanced the invasive activity or the Akt, ERK, NF-κB and MMP activity in a uterine cervical cancer cell line (CaSki) by a western blot analysis. The patients with enhanced CD24 expression had a higher rate of advanced clinical stage (50 vs. 16.5%, p<0.01), lymph node metastasis (34.6 vs. 14.3%) and lymphovascular involvement (65.4 vs. 20.4%, p=0.01), and a poor overall and disease-free survival (5-year survival rate: 62 vs. 86%, p=0.03). CD24 overexpression in CaSki cells resulted in activation of Cell Signaling proteins, including Akt, ERK, NF-κB and MMP-9. An invasion assay showed that CD24 overexpression in CaSki cells led to increased invasion ability. The CD24 overexpression also increased mRNA expression of Slug but not Snail. Moreover, the CD24 overexpression also decreased expression of E-cadherin and increased N-cadherin protein levels. Increased expression of CD24 may be associated with tumor progression and prognosis in patients with uterine cervical cancer. CD24 expression may therefore be used not only as a prognostic marker in uterine cervical cancer, but also as a target for the development of new therapeutic approaches.

Doublecortin-like kinase 1 is elevated serologically in pancreatic ductal adenocarcinoma and widely expressed on circulating tumor cells

Doublecortin-like kinase 1 (DCLK1) is a putative pancreatic stem cell marker and is upregulated in pancreatic cancer, colorectal cancer, and many other solid tumors. It marks tumor stem cells in mouse models of intestinal neoplasia. Here we sought to determine whether DCLK1 protein can be detected in the bloodstream and if its levels in archived serum samples could be quantitatively assessed in pancreatic cancer patients. DCLK1 specific ELISA, western blotting, and immunohistochemical analyses were used to determine expression levels in the serum and staining intensity in archived tumor tissues of pancreatic ductal adenocarcinoma (PDAC) patients and in pancreatic cancer mouse models. DCLK1 levels in the serum were elevated in early stages of PDAC (stages I and II) compared to healthy volunteers (normal controls). No differences were observed between stages III/IV and normal controls. In resected surgical tissues, DCLK1 expression intensity in the stromal cells was significantly higher than that observed in tumor epithelial cells. Circulating tumor cells were isolated from KPCY mice and approximately 52% of these cells were positive for Dclk1 staining. Dclk1 levels in the serum of KPC mice were also elevated. We have previously demonstrated that DCLK1 plays a potential role in regulating epithelial mesenchymal transition (EMT). Given the increasingly recognized role of EMT derived stem cells in cancer progression and metastasis, we hypothesize that DCLK1 may contribute to the metastatic process. Taken together, our results suggest that DCLK1 serum levels and DCLK1 positive circulating tumor cells should be further assessed for their potential diagnostic and prognostic significance.

Regulation of miRNAs by agents targeting the tumor stem cell markers DCLK1, MSI1, LGR5, and BMI1

Gastrointestinal cancers such as colorectal, pancreatic, liver, gastric, and esophageal, are the most common forms of malignant cancers. MicroRNAs (miRNA) play important role in regulating gastrointestinal cancer progress either as potent oncogenes or tumor suppressors. In this report, we will discuss the importance of several tumor suppressors involved in colon or pancreatic cancer. Some recent studies on tumor stem cells and regulation of these miRNAs via agents targeting the tumor stem cell markers doublecortin-like kinase 1 (DCLK1), Musashi-1 (MSI1), polycomb protein BMI1, and WNT genes (LGR5 and ASCL2) will also be discussed. Agents such as siRNA/shRNA, small molecule kinase inhibitors, and general herbal drugs (curcumin) targeting these tumor stem cell markers and tumor suppressor miRNAs could be the perfect therapeutic agents for the treatment of these cancers.

Understanding epithelial homeostasis in the intestine: An old battlefield of ideas, recent breakthroughs and remaining controversies

The intestinal epithelium constitutes the barrier between the gut lumen and the rest of the body and a very actively renewing cell population. The crypt/villus and crypt/cuff units of the mouse small intestine and colon are its basic functional units. The field is confronted with competing concepts with regard to the nature of the cells that are responsible for all the day-to day cell replacement and those that act to regenerate the tissue upon injury and with two diametrically opposed models for lineage specification. The review revisits groundbreaking pioneering studies to provide non expert readers and crypt watchers with a factual analysis of the origins of the current models deduced from the latest spectacular advances. It also discusses recent progress made by addressing these issues in the crypts of the colon, which need to be better understood, since they are the preferred sites of major pathologies.

XMD8-92 inhibits pancreatic tumor xenograft growth via a DCLK1-dependent mechanism

XMD8-92 is a kinase inhibitor with anti-cancer activity against lung and cervical cancers, but its effect on pancreatic ductal adenocarcinoma (PDAC) remains unknown. Doublecortin-like kinase1 (DCLK1) is upregulated in various cancers including PDAC. In this study, we showed that XMD8-92 inhibits AsPC-1 cancer cell proliferation and tumor xenograft growth. XMD8-92 treated tumors demonstrated significant downregulation of DCLK1 and several of its downstream targets (including c-MYC, KRAS, NOTCH1, ZEB1, ZEB2, SNAIL, SLUG, OCT4, SOX2, NANOG, KLF4, LIN28, VEGFR1, and VEGFR2) via upregulation of tumor suppressor miRNAs let-7a, miR-144, miR-200a-c, and miR-143/145; it did not however affect BMK1 downstream genes p21 and p53. These data taken together suggest that XMD8-92 treatment results in inhibition of DCLK1 and downstream oncogenic pathways (EMT, pluripotency, angiogenesis and anti-apoptotic), and is a promising chemotherapeutic agent against PDAC.

Human colorectal CD24+ cancer stem cells are susceptible to epithelial-mesenchymal transition

Conventional cancer chemotherapy preferentially destroys non-stem cancer cells within a tumor, and a subpopulation of cancer stem cells (CSCs) is more resistant and survives, leading to relapses and metastasis. Howeve, recent studies suggest that CD24 and susceptibility to epithelial-mesenchymal transition (EMT) can serve as markers of CSCs. We report that CD24(+) cells are susceptible to induction of EMT, a phenotype important for cancer metastasis. We studied the responsiveness of CSC markers to TGF-β , an effective EMT inducer. The data on CD24 demonstrated that CD24(+) cells are susceptible to EMT, a phenotype important for cancer metastasis in two colorectal cancer cell lines, the CaR-1 and CCK81. CD24(+) cells expressed Notch 1 in response to exposure to TGF-β in culture and showed higher tumorigenic activity compared to controls. This evidence shows that CD24(+) cells are susceptible to EMT induction and to cancer progression and is indicative of the candidacy of CD24 as a therapeutic target in CSC.

Location-specific effect of microbiota and MyD88-dependent signaling on Wnt/β-catenin pathway and intestinal stem cells

Intestinal homeostasis depends on the proper activity of the intestinal stem cells (ISCs) and an appropriate host response to the normal resident microbiota. The question on the effect of microbiota on ISCs behavior has not been addressed yet. Canonical Wnt pathway and ISC gene expression signature was compared in germfree vs. conventional and MyD88(-/-) vs. Myd88(+/+) mice based on publicly available gene expression data sets. Microbiota and MyD88-dependent signaling have distinct effects on the Wnt pathway and ISC at gene expression level. In addition, the effect of microbiota and MyD88-dependent signaling on Wnt pathway and ISCs show regional variation. The net effect of microbiota on Wnt pathway and ISCs cannot be inferred from the available data. Nonetheless, the data are suggestive of a potential regulatory mechanism of the Wnt pathway by the microbiota and plausibly by any alteration in the microbiota composition.

Development of intestinal organoids as tissue surrogates: cell composition and the epigenetic control of differentiation

Intestinal organoids are multicellular crypt-like structures that can be derived from adult intestinal stem cells (ISCs), embryonic stem cells (ESCs) or induced pluripotent stem cells (IPSCs). Here we show that intestinal organoids generated from mouse ESCs were enriched in ISCs and early progenitors. Treatment of these organoids with a γ-secretase inhibitor increased Math1 and decreased Hes1 expression, indicating Notch signaling regulates ISC differentiation in these organoids. Lgr5 and Tert positive ISCs constituted approximately 10% and 20% of the organoids. As found in native tissue, Lgr5 and Tert expressing cells resolved into two discreet populations, which were stable over time. Intestinal organoids derived from cancer-prone Apc(Min/+) mice showed similar numbers of ISCs, but had reduced Math1 expression, indicating a suppressed secretory cell differentiation potential (as found in intestinal tissue). Apc(Min/+) organoids were used to screen epigenetically active compounds for those that increased Math1 expression and organoid differentiation (including HDAC inhibitors, Sirtuin (SIRT) modulators and methyltransferase inhibitors). Broad-spectrum HDAC inhibitors increased both Math1 and Muc2 expression, indicating an ability to promote the suppressed secretory cell differentiation pathway. Other epigenetic compounds had a diverse impact on cell differentiation, with a strong negative correlation between those that activated the secretory marker Muc2 and those that activated the absorptive cell marker Fabp2. These data show that ESC-derived intestinal organoids can be derived in large numbers, contain distinct ISC types and can be used to screen for agents that promote cell differentiation through different lineage pathways.

Increased expression of CD24 is associated with tumor progression and prognosis in patients suffering osteosarcoma

OBJECTIVE

As a small heavily glycosylated mucin-like glycosyl-phosphatidylinositol-anchored cell surface protein, CD24 plays an important role in carcinogenesis of various human malignancies. However, its involvement in osteosarcoma is still unclear. The aim of this study was to investigate the expression pattern and the clinical significance of CD24 in human osteosarcoma.

METHODS

CD24 mRNA and protein expression levels were, respectively, detected by RT-PCR and Western blot assays using 30 pairs of osteosarcoma and noncancerous bone tissues. Then, immunohistochemistry was performed to analyze the association of CD24 expression in 166 osteosarcoma tissues with clinicopathological factors or survival of patients.

RESULTS

CD24 expression at mRNA and protein levels were both significantly higher in osteosarcoma tissues than those in corresponding noncancerous bone tissues (both P < 0.001). In addition, CD24 protein was positively expressed in 129 of 166 (77.7 %) osteosarcoma specimens with a cytoplasmic and membraneous staining, and also increased in the osteosarcoma specimens with advanced clinical stage (P = 0.01) and positive distant metastasis (P = 0.005). The univariate and multivariate analyses showed that osteosarcoma patients with high CD24 expression had poorer overall and disease-free survival, and high CD24 expression was an independent prognostic factor for both overall and disease-free survival.

CONCLUSION

The aforementioned findings offer convincing evidence for the first time that the increased expression of CD24 is correlated with tumor aggressiveness and tumor metastasis of osteosarcoma, and this molecule is an independent prognostic marker for osteosarcoma patients.