Cytometric and biochemical characterization of human breast cancer cells reveals heterogeneous myoepithelial phenotypes

Cadmium nanocluster as a safe nanocarrier: biodistribution in BALB/c mice and application to carry crocin to breast cancer cell lines

Aim

Metal nanoclusters are emerging nanomaterials applicable for drug delivery. Here, the toxicity and oxidative stress induction of divalent cationic cadmium (Cd2+) was compared with a Cd in the form of nanocluster. Then, it was used for targeted drug delivery into breast cancer cell lines.

Methods

Using a green chemistry route, a Cd nanocluster (Cd-NC) was synthesized based on bovine serum albumin. After characterization, its genotoxicity and oxidative stress induction were studied in both in vitro and in vivo. After that, it was conjugated with hyaluronic acid (HA). The efficiency of hyaloronized-Cd-CN (HA-Cd-NC) for loading and releasing crocin (Cro), an anticancer phytochemical, was studied. Finally, it was applied for cell death induction in a panel of breast cancer cell lines.

Results

The comet assay results indicated that, unlike Cd2+ and potassium permanganate (KMnO4), no genotoxicity and oxidative stress was induced by Cd-NC in vitro. Then, the pharmacokinetics of this Cd-NC was studied in vivo. The data showed that Cd-NC has accumulated in the liver and excreted from the feces of mice. Unlike Cd2+, no toxicity and oxidative stress were induced by this Cd-NC in animal tissues. Then, the Cd-NC was targeted toward breast cancer cells by adding HA, a ligand for the CD44 cell surface receptor. After that, Cro was loaded on HA-Cd-NC and it was used for the treatment of a panel of human breast cancer cell lines with varying degrees of CD44. The half-maximal drug inhibitory concentration (IC50) of Cro was significantly decreased when it was loaded on HA-Cd-NC, especially in MDA-MB-468 with a higher degree of CD44 at the surface. These results indicate the higher toxicity of Cro toward breast cancers when carried out by HA-Cd-NC.

Conclusions

The Cd-NC was completely safe and is a promising candidate for delivering anticancer drugs/phytochemicals into the targeted breast tumors.

Impact of media compositions and culture systems on the immunophenotypes of patient-derived breast cancer cells

BACKGROUND

Heterogeneous tumor cells are thought to be a significant factor in the failure of endocrine therapy in estrogen receptor-positive (ER+) cancers. Culturing patient-derived breast cancer cells (PDBCCs) provides an invaluable tool in pre-clinical and translational research for the heterogeneity of cancer cells. This study aimed to investigate the effects of different media components and culture methods on the BCSC-associated immunophenotypes and gene expression in ER + PDBCCs.

METHODS

Ten patients with ER + breast cancer were employed in this study, six of whom had neoadjuvant chemotherapy and four of whom did not. PDBCCs were isolated by enzymatic methods using collagen I and hyaluronidase. PDBCCs were grown as monolayers in mediums with different compositions and as multicellular spheroid in a suspended condition. Collagen I-coated plate and ultralow attachment plate coated with polymer-X were used for monolayer and spheroid culture. Flow cytometry, immunofluorescent staining, RT-PCR, and RNA-sequencing were employed to examine the immunophenotype and genetic profile of PDBCCs.

RESULTS

More than 95% of PDBCCs sustain EpCAM high/+/fibroblast marker- phenotypes in monolayer conditions by subculturing 3-4 times. A83-01 removal induced senescent cells with high β-galactosidase activity. PDBCCs grown as monolayers were characterized by the majority of cells having an EpCAM+/CD49f + phenotype. Compared to full media in monolayer culture, EGF removal increased EpCAM+/CD49f - phenotype (13.8-fold, p = 0.028), whereas R-spondin removal reduced it (0.8-fold, p = 0.02). A83-01 removal increased EpCAM+/CD24 + phenotype (1.82-fold, p = 0.023) and decreased EpCAM low/-/CD44+/CD24- phenotype (0.45-fold, p = 0.026). Compared to monolayer, spheroid resulted in a significant increase in the population with EpCAM-/CD49+ (14.6-fold, p = 0.006) and EpCAM low/-/CD44+/CD24- phenotypes (4.16-fold, p = 0.022) and ALDH high activity (9.66-fold, p = 0.037). ALDH1A and EMT-related genes were upregulated. In RNA-sequencing analysis between spheroids and monolayers, a total of 561 differentially expressed genes (2-fold change, p < 0.05) were enriched in 27 KEGG pathways including signaling pathways regulating pluripotency of stem cells. In a recurrence-free survival analysis based on the Kaplan-Meier Plotter database of the up-and down-regulated genes identified in spheroids, 15 up-, and 14 down-regulated genes were associated with poor prognosis of breast cancer patients.

CONCLUSION

The media composition and spheroid culture method change in the BCSCs and EMT markers of PDBCCs, implying the importance of defining the media composition and culture method for studying PDBCCs in vitro.

Expression of type VI collagen α3 chain in canine mammary carcinomas

This study aimed to investigate the expression of type VI collagen α3 chain (COL6a3) in neoplastic cells of canine mammary gland carcinomas (CMGCs) using immunohistochemistry (IHC) and to evaluate the association between COL6a3 expression and tumor histological features, histological grades, and the differentiation status of neoplastic epithelial cells. COL6a3 expression in carcinoma cells was significantly associated with histologically low malignancy and low mitotic indices. In addition, COL6a3+ carcinoma cells were more frequently detected in simple carcinomas (tubular and tubulopapillary types) than in solid carcinomas. These findings indicate that reduced expression of COL6a3 in carcinoma cells contributes to the malignant phenotype in CMGCs. We also showed that COL6a3 expression in the carcinoma cells was more frequently detected in CK19+/CD49f + and/or CK19+/CK5+ tumors. In addition, COL6a3+/CK19+/CD49f + and COL6a3+/CK19+/CK5+ tumors consisted of CK19+/CD49f + and CK19+/CD49f- cells, and CK19+/CK5+ and CK19+/CK5- cells, respectively. Most of these tumors more frequently expressed GATA3, but not Notch1. These results indicate that COL6a3 is expressed in CMGCs containing both luminal progenitor-like and mature luminal-like cells and showing differentiation ability into mature luminal cells. It is possible that COL6 may be involved in the differentiation of luminal progenitor-like carcinoma cells into mature luminal-like carcinoma cells in CMGCs, which may suppresses the development of malignant phenotypes in CMGCs.

Nuclear Deformability of Breast Cells Analyzed from Patients with Malignant and Benign Breast Diseases

Breast cancer is a heterogeneous and dynamic disease, in which cancer cells are highly responsive to alterations in the microenvironment. Today, conventional methods of detecting cancer give a rather static image of the condition of the disease, so dynamic properties such as invasiveness and metastasis are difficult to capture. In this study, conventional molecular-level evaluations of the patients with breast adenocarcinoma were combined with in vitro methods on micropatterned poly(methyl methacrylate) (PMMA) biomaterial surfaces that deform cells. A correlation between deformability of the nuclei and cancer stemness, invasiveness, and metastasis was sought. Clinical patient samples were from regions of the breast with different proximities to the tumor. Responses at the single-cell level toward the micropatterned surfaces were studied using CD44/24, epithelial cell adhesion marker (EpCAM), MUC1, and PCK. Results showed that molecular markers and shape descriptors can discriminate the cells from different proximities to the tumor center and from different patients. The cells with the most metastatic and invasive properties showed both the highest deformability and the highest level of metastatic markers. In conclusion, by using a combination of molecular markers together with nuclear deformation, it is possible to improve detection and separation of subpopulations in heterogenous breast cancer specimens at the single-cell level.

Does DPP-IV Inhibition Offer New Avenues for Therapeutic Intervention in Malignant Disease?

Simple Summary

There is growing interest in identifying the effects of antidiabetic agents on cancer risk, progression, and anti-cancer treatment due to the long-term use of these medications and the inherently increased risk of malignancies in diabetic patients. Tumor development and progression are affected by multiple mediators in the tumor microenvironment, several of which may be proteolytically modified by the multifunctional protease dipeptidyl peptidase-IV (DPP-IV, CD26). Currently, low-molecular-weight DPP-IV inhibitors (gliptins) are used in patients with type 2 diabetes based on the observation that DPP-IV inhibition enhances insulin secretion by increasing the bioavailability of incretins. However, the DPP-IV-mediated cleavage of other biopeptides and chemokines is also prevented by gliptins. The potential utility of gliptins in other areas of medicine, including cancer, is therefore being evaluated. Here, we critically review the existing evidence on the role of DPP-IV inhibitors in cancer pathogenesis, their potential to be used in anti-cancer treatment, and the possible perils associated with this approach.

Abstract

Dipeptidyl peptidase IV (DPP-IV, CD26) is frequently dysregulated in cancer and plays an important role in regulating multiple bioactive peptides with the potential to influence cancer progression and the recruitment of immune cells. Therefore, it represents a potential contributing factor to cancer pathogenesis and an attractive therapeutic target. Specific DPP-IV inhibitors (gliptins) are currently used in patients with type 2 diabetes mellitus to promote insulin secretion by prolonging the activity of the incretins glucagon-like peptide 1 (GLP-1) and glucose-dependent insulinotropic polypeptide (GIP). Nevertheless, the modulation of the bioavailability and function of other DPP-IV substrates, including chemokines, raises the possibility that the use of these orally administered drugs with favorable side-effect profiles might be extended beyond the treatment of hyperglycemia. In this review, we critically examine the possible utilization of DPP-IV inhibition in cancer prevention and various aspects of cancer treatment and discuss the potential perils associated with the inhibition of DPP-IV in cancer. The current literature is summarized regarding the possible chemopreventive and cytotoxic effects of gliptins and their potential utility in modulating the anti-tumor immune response, enhancing hematopoietic stem cell transplantation, preventing acute graft-versus-host disease, and alleviating the side-effects of conventional anti-tumor treatments.

CD26/DPP-4 in Chronic Myeloid Leukemia

CD26 expression is altered in many solid tumors and hematological malignancies. Recently, it has been demonstrated that it is a specific marker expressed on LSCs of CML, both in BM and PB samples, and absent on CD34+/CD38− stem cells in normal subjects or on LSCs of other myeloid neoplasms. CD26+ LSCs have been detected by flow-cytometry assays in all PB samples of Chronic-Phase CML patients evaluated at diagnosis. Additionally, it has been demonstrated that most CML patients undergoing Tyrosine Kinase Inhibitors (TKIs) treatment still harbored circulating measurable residual CD26+ LSCs, even when displaying a consistent deep molecular response without any significant association among the amounts of BCR-ABL transcript and CD26+ LSCs. Preliminary data of our Italian prospective multicenter study showed that CML patients with a poorer response presented with a higher number of CD26+ LSCs at diagnosis. These data confirmed that CD26 is a specific marker of CML and suggest that it could be considered for the monitoring of therapeutic responses.

Discovery of tight-binding competitive inhibitors of dipeptidyl peptidase IV

Dipeptidyl peptidase IV (DPP-IV, EC 3.4.14.5) is an abundant serine aminopeptidase that preferentially cleaves N-terminal Xaa-Pro or Xaa-Ala dipeptides from oligopeptides. Inhibitors of DPP-IV activity are used for treating type 2 diabetes mellitus and other diseases. DPP-IV is also involved in tumor progression. We identified four new non-peptide tight-binding competitive inhibitors of porcine DPP-IV by virtual screening and enzymatic assays. Molecular docking simulations supported the competitive behavior, and the selectivity of one of the compounds in the DPP-IV family. Since three of these inhibitors are also aminopeptidase N (APN) inhibitors, we tested their impact on APN+/DPP-IV+ and DPP-IV+ human tumor cells' viability. Using kinetic assays, we determined that HL-60 tumor cells express both APN and DPP-IV activities and that MDA-MB-231 tumor cells express DPP-IV activity. The inhibitors had a slight inhibitory effect on human HEK-293 cell viability but reduced the viability of APN+/DPP-IV+ and DPP-IV+ human tumor cells more potently. Remarkably, the intraperitoneal injection of these compounds inhibited DPP-IV activity in rat brain, liver, and pancreas. In silico studies suggested inhibitors binding to serum albumin contribute to blood-brain barrier crossing. The spectrum of action of some of these compounds may be useful for niche applications.

Nonspecific nuclear uptake of anti-MUC1 aptamers by dead cells: the role of cell viability monitoring in aptamer targeting of membrane-bound protein cancer biomarkers

Most aptamers targeting cell-expressed antigens are intended for in vivo application, however, these sequences are commonly generated in vitro against synthetic oligopeptide epitopes or recombinant proteins. As these in vitro analogues frequently do not mimic the in vivo target within an endogenous environment, the evolved aptamers are often prone to nonspecific binding. The presence of dead cells and cellular debris further complicate aptamer targeting, due to their high nonspecific affinities to single-stranded DNA. Despite these known limitations, assessment of cell viability and/or the removal of dead cells is rarely applied as part of the methodology during in vivo testing of aptamer binding. Furthermore, the extent and route(s) by which dead cells uptake existing aptamers remains to be determined in the literature. For this purpose, the previously reported aptamer sequences 5TR1, 5TR4, 5TRG2 and S22 - enriched against the MUC1 tumour marker of the mucin glycoprotein family - were used as model sequences to evaluate the influence of cell viability and the presence of nontarget cell-expressed protein on aptamer binding to the MUC1 expressing human cancer cell lines MCF-7, Hs578T, SW480, and SW620. From fluorescence microscopy analysis, all tested aptamers demonstrated extensive nonspecific uptake within the nuclei of dead cells with compromised membrane integrities. Using fluorescent-activated cell sorting (FACS), the inclusion of excess double-stranded DNA as a blocking agent showed no effect on nonspecific aptamer uptake by dead cells. Further nonspecific binding to cell-membrane bound and intracellular protein was evident for each aptamer sequence, as assessed by southwestern blotting and FACS. These factors likely contributed to the ∼120-fold greater binding response of the 5TR1 aptamer to dead MCF-7 cells over equivalent live cell populations. The identification of dead cells and cellular debris using viability stains and the subsequent exclusion of these cells from FACS analysis was identified as an essential requirement for the evaluation of aptamer binding specificity to live cell populations of the cancer cell lines MCF-7, Hs578T and SW480. The research findings stress the importance of dead cell uptake and more comprehensive cell viability screening to validate novel aptamer sequences for diagnostic and therapeutic application.

Diagnostic significance of apical membranous and cytoplasmic dot-like CD26 expression in encapsulated follicular variant of papillary thyroid carcinoma: a useful marker for capsular invasion

Non-invasive follicular thyroid neoplasm with papillary-like nuclear features (NIFTP) and invasive encapsulated follicular variant of papillary thyroid carcinoma (EFV-PTC) are indistinguishable preoperatively. CD26 expression in follicular tumor-uncertain malignant potential (FT-UMP) is reported to be clearly higher than in that without capsular invasion. To verify the diagnostic significance of CD26 immunostaining in EFV-PTC, we examined the expression pattern of CD26 in non-invasive EFV-PTC (NIFTP) and invasive EFV-PTC. We performed immunohistochemical analysis using CD26 antibody for 37 NIFTPs and 54 EFV-PTCs (34 minimally invasive EFV-PTCs and 20 widely invasive EFV-PTCs). Most NIFTP samples showed an apical membranous pattern or a cytoplasmic diffuse pattern of expression. Invasive EFV-PTCs more frequently showed a cytoplasmic dot-like pattern, and the labeling indices of tumor cells with cytoplasmic dot-like patterns were significantly higher than those in NIFTPs. The sizes of dots seen in NIFTPs (mean: 1.12 μm) were significantly smaller than in invasive EFV-PTCs (1.33 μm), minimally invasive EFV-PTC (1.27 μm), and widely invasive EFV-PTC (1.38 μm). We, therefore, conclude that cytoplasmic diffuse and/or cytoplasmic dot-like CD26 expression, particularly the larger CD26-positive dots, could be useful markers for capsular invasion in EFV-PTC. CD26 immunostaining, using cell blocks or cytological specimens, may preoperatively distinguish between NIFTP and invasive EFV-PTC.

The MSC-MCF-7 Duet Playing Tumor Vasculogenesis and Angiogenesis onto the Chick Embryo Chorioallantoic Membrane

BACKGROUND/AIM

Human mesenchymal stem cells (hMSC) represent a versatile cell population, able to modulate the tumor microenvironment. Our aim was to recreate an open scene for the in vivo interaction between hMSC and the MCF-7 breast cancer cells (MCF-7), in order to enlighten the intimate involvement of hMSC in tumor vasculogenesis and angiogenesis.

MATERIALS AND METHODS

hMSC and MCF-7 were seeded onto the chick embryo chorioallantoic membrane (CAM) and incubated for 7 days. Consecutively, the morphology and the immunohistochemical profile of CAM were assessed.

RESULTS

Following this complex interaction, MCF-7 acquired a more aggressive phenotype, hMSC switched to a vascular precursor phenotype, while CAM underwent a major reset to an earlier stage, with hotspots of angiogenesis, vasculogenesis and hematopoiesis.

CONCLUSION

The hallmark of this study was the establishment of a veritable in vivo experimental model of MSC involvement in tumor vasculogenesis and angiogenesis, allowing further analysis in the field.

An altered lipid metabolism characterizes Charcot-Marie-Tooth type 2B peripheral neuropathy

Charcot-Marie Tooth type 2B (CMT2B) is a rare inherited peripheral neuropathy caused by five missense mutations in the RAB7A gene, which encodes a small GTPase of the RAB family. Currently, no cure is available for this disease. In this study, we approached the disease by comparing the lipid metabolism of CMT2B-derived fibroblasts to that of healthy controls. We found that CMT2B cells showed increased monounsaturated fatty acid level and increased expression of key enzymes of monounsaturated and polyunsaturated fatty acid synthesis. Moreover, in CMT2B cells a higher expression of acetyl-CoA carboxylase (ACC) and fatty acid synthase (FAS), key enzymes of de novo fatty acid synthesis, with a concomitantly increased [1-¹⁴C]acetate incorporation into fatty acids, was observed. The expression of diacylglycerol acyltransferase 2, a rate-limiting enzyme in triacylglycerol synthesis, as well as triacylglycerol levels were increased in CMT2B compared to control cells. In addition, as RAB7A controls lipid droplet breakdown and lipid droplet dynamics have been linked to diseases, we analyzed these organelles and showed that in CMT2B cells there is a strong accumulation of lipid droplets compared to control cells, thus reinforcing our data on abnormal lipid metabolism in CMT2B. Furthermore, we demonstrated that ACC and FAS expression levels changed upon RAB7 silencing or overexpression in HeLa cells, thus suggesting that metabolic modifications observed in CMT2B-derived fibroblasts can be, at least in part, related to RAB7 mutations.

Cell Membrane Nanostructure is Altered by Heat-Induced Antigen Retrieval: A Possible Consequence for Immunocytochemical Detection of Membranous Antigens

Heat-induced antigen retrieval (HIAR) treatment improves the antigen immunodetection in formalin-fixed, paraffin-embedded tissue samples and it can also improve the detection of intracellular antigens in alcohol-fixed cytological samples, although it could deleteriously impact immunodetection, particularly that of membranous antigens. We examined the differences in cell surface topography on MCF7 cells fixed in methanol/acetone (M/A) or 4% paraformaldehyde (4% PFA), as well as the changes caused by HIAR treatment at three different temperatures (60, 90, and 120°C), using atomic force microscopy. Furthermore, the consequences for immunostaining of five membranous antigens [epidermal growth factor receptor (EGFR), E-cadherin, CD9, CD24, and CD44] were examined. Our results illustrate that while there was no one single optimal immunostaining condition for the tested antibodies, the surface topography could be an important factor in successful staining. Generally, the best conditions for successful immunostaining were M/A fixation with no HIAR treatment, whereas in 4% PFA-fixed cells, HIAR treatment at 120°C was optimal. These conditions showed similarity in cell surface skewness. A correlation factor between successful immunocytochemical staining and the skewness parameter was 0.8000. Our results indicate that the presence of valleys, depressions, scratches, and pits on the cell surface is unfavorable for the successful immunodetection of cell surface antigens.

CD26/DPP4 - a potential biomarker and target for cancer therapy

CD26/dipeptidyl peptidase (DPP)4 is a membrane-bound protein found in many cell types of the body, and a soluble form is present in body fluids. There is longstanding evidence that various primary tumors and also metastases express CD26/DPP4 to a variable extent. By cleaving dipeptides from peptides with a proline or alanine in the penultimate position at the N-terminus, it regulates the activity of incretin hormones, chemokines and many other peptides. Due to these effects and interactions with other molecules, a tumor promoting or suppressing role can be attributed to CD26/DPP4. In this review, we discuss the existing evidence on the expression of soluble or membrane-bound CD26/DPP4 in malignant diseases, along with the most recent findings on CD26/DPP4 as a therapeutic target in specific malignancies. The expression and possible involvement of the related DPP8 and DPP9 in cancer are also reviewed. A higher expression of CD26/DPP4 is found in a wide variety of tumor entities, however more research on CD26/DPP4 in the tumor microenvironment is needed to fully explore its use as a tumor biomarker. Circulating soluble CD26/DPP4 has also been studied as a cancer biomarker, however, the observed decrease in most cancer patients does not seem to be cancer specific. Encouraging results from experimental work and a recently reported first phase clinical trial targeting CD26/DPP4 in mesothelioma, renal and urological tumors pave the way for follow-up clinical studies, also in other tumor entities, possibly leading to the development of more effective complementary therapies against cancer.

High Expression of CD200 and CD200R1 Distinguishes Stem and Progenitor Cell Populations within Mammary Repopulating Units

Aiming to unravel the top of the mammary epithelial cell hierarchy, a subset of the CD49f^highCD24^med mammary repopulating units (MRUs) was identified by flow cytometry, expressing high levels of CD200 and its receptor CD200R1. These MRU^{CD200/CD200R1} repopulated a larger area of de-epithelized mammary fat pads than the rest of the MRUs, termed MRU^{not CD200/CD200R1}. MRU^{CD200/CD200R1} maintained a much lower number of divergently defined, highly expressed genes and pathways that support better cell growth, development, differentiation, and progenitor activity than their MRU^{not CD200/CD200R1} counterparts. A defined profile of hierarchically associated genes supporting a single-lineage hypothesis was confirmed by in vitro mammosphere analysis that assembled 114 genes with decreased expression from MRU^{CD200/CD200R1} via MRU^{not CD200/CD200R1} toward CD200⁺CD200R1^- and CD200R1⁺CD200^- cells. About 40% of these genes were shared by a previously published database of upregulated genes in mammary/breast stem cells and may represent the core genes involved in mammary stemness.

Alterations of autophagy in the peripheral neuropathy Charcot-Marie-Tooth type 2B

Charcot-Marie-Tooth type 2B (CMT2B) disease is a dominant axonal peripheral neuropathy caused by 5 mutations in the RAB7A gene, a ubiquitously expressed GTPase controlling late endocytic trafficking. In neurons, RAB7A also controls neuronal-specific processes such as NTF (neurotrophin) trafficking and signaling, neurite outgrowth and neuronal migration. Given the involvement of macroautophagy/autophagy in several neurodegenerative diseases and considering that RAB7A is fundamental for autophagosome maturation, we investigated whether CMT2B-causing mutants affect the ability of this gene to regulate autophagy. In HeLa cells, we observed a reduced localization of all CMT2B-causing RAB7A mutants on autophagic compartments. Furthermore, compared to expression of RAB7A^WT, expression of these mutants caused a reduced autophagic flux, similar to what happens in cells expressing the dominant negative RAB7A^T22N mutant. Consistently, both basal and starvation-induced autophagy were strongly inhibited in skin fibroblasts from a CMT2B patient carrying the RAB7A^V162M mutation, suggesting that alteration of the autophagic flux could be responsible for neurodegeneration.

Endoglin based in vivo near-infrared fluorescence imaging of tumor models in mice using activatable liposomes

BACKGROUND

Endoglin (CD105) is overexpressed on tumor cells and tumor vasculatures, making it a potential target for diagnostic imaging and therapy of different neoplasms. Therefore, studies on nanocarrier systems designed for endoglin-directed diagnostic and drug delivery purposes would expose the feasibility of targeting endoglin with therapeutics.

METHODS

Liposomes carrying high concentrations of a near-infrared fluorescent dye in the aqueous interior were prepared by the lipid film hydration and extrusion procedure, then conjugated to single chain antibody fragments either selective for murine endoglin (termed mEnd-IL) or directed towards human endoglin (termed hEnd-IL). A combination of Dynamic Light Scattering, electron microscopy, cell binding and uptake assays, confocal microscopy and in vivo fluorescence imaging of mice bearing xenografted human breast cancer and human fibrosarcoma models were implemented to elucidate the potentials of the liposomes.

RESULTS

The mEnd-IL and hEnd-IL were highly selective for the respective murine- and human endoglin expressing cells in vitro and in vivo. Hence, the hEnd-IL bound distinctly to the tumor cells and enabled suitable fluorescence imaging of the tumors, whereas the mEnd-IL bound the tumor vasculature, but also to the liver, kidney and lung vasculature of mice.

CONCLUSIONS

The work highlights key differences between targeting vascular (murine) and neoplastic (human) endoglin in animal studies, and suggests that the hEnd-IL can serve as a delivery system that targets human endoglin overexpressed in pathological conditions.

GENERAL SIGNIFICANCE

The endoglin-targeting liposomes presented herewith represent strategic tools for the future implementation of endoglin-directed neoplastic and anti-angiogenic therapies.

Antibody-based cell-surface proteome profiling of metastatic breast cancer primary explants and cell lines

Flow cytometric cell surface proteomics provides a new and powerful tool to determine changes accompanying neoplastic transformation and invasion, providing clues to essential interactions with the microenvironment as well as leads for potential therapeutic targets. One of the most important advantages of flow cytometric cell surface proteomics is that it can be performed on living cells that can be sorted for further characterization and functional studies. Here, we document the surface proteome of clonogenic metastatic breast cancer (MBrCa) explants, which was strikingly similar to that of normal mesenchymal stromal cells (P = 0.017, associated with Pearson correlation coefficient) and transformed mammary epithelial cells (P = 0.022). Markers specifically upregulated on MBrCa included CD200 (Ox2), CD51/CD61 (Integrin α5/β3), CD26 (dipeptidyl peptidase-4), CD165 (c-Cbl), and CD54 (ICAM-1). Proteins progressively upregulated in a model of neoplastic transformation and invasion included CD26, CD63 (LAMP3), CD105 (Endoglin), CD107a (LAMP1), CD108 (Semaphorin 7A), CD109 (Integrin β4), CD151 (Raph blood group), and disialoganglioside G2. The proteome of the commonly used cell lines MDA-MB-231, MCF7, and BT-474 were uncorrelated with that of MBrCa (P = 1.0, 1.0, 0.9, respectively). The comparison has demonstrated the mesenchymal nature of clonogenic cells isolated by short-term culture of metastatic breast cancer, provided several leads for biomarkers and potential targets for anti-invasive therapy, including CD200, and highlighted the limitations of breast cancer cell lines for representing the cell surface biology of breast cancer. © 2017 International Society for Advancement of Cytometry.

DPPIV promotes endometrial carcinoma cell proliferation, invasion and tumorigenesis

Dipeptidyl peptidase IV (DPPIV), also known as CD26, is a 110-kDa cell surface glycoprotein expressed in various tissues. DPPIV reportedly plays a direct role in the progression of several human malignancies. DPPIV specific inhibitors are employed as antidiabetics and could potentially be repurposed to enhance anti-tumor immunotherapies. In the present study, we investigated the correlation between DPPIV expression and tumor progression in endometrial carcinoma (EC). DPPIV overexpression altered cell morphology and stimulated cell proliferation, invasion and tumorigenesis in vitro and in vivo. These effects were abrogated by DPPIV knockdown or pharmacological inhibition using sitagliptin. DPPIV overexpression increased hypoxia-inducible factor 1a (HIF-1a) and vascular endothelial growth factor A (VEGFA) expression to promote HIF-1a-VEGFA signaling. Our results indicated that DPPIV accelerated endometrial carcinoma progression and that sitagliptin may be an effective anti-EC therapeutic.

Inhibition of dipeptidyl peptidase IV prevents high fat diet-induced liver cancer angiogenesis by downregulating chemokine ligand 2

Obesity is a major risk factor for hepatocellular carcinoma (HCC) and is typically accompanied by higher levels of serum dipeptidyl peptidase 4 (DPP4). However, the role of DPP4 in obesity-promoted HCC is unclear. Here, we found that consumption of a high-fat diet (HFD) promoted HCC cell proliferation and metastasis and led to poor survival in a carcinogen-induced model of HCC in rats. Notably, genetic ablation of DPP4 or treatment with a DPP4 inhibitor (vildagliptin) prevented HFD-induced HCC. Moreover, HFD-induced DPP4 activity facilitated angiogenesis and cancer cell metastasis in vitro and in vivo, and vildagliptin prevented tumor progression by mediating the pro-angiogenic role of chemokine ligand 2 (CCL2). Loss of DPP4 effectively reversed HFD-induced CCL2 production and angiogenesis, indicating that the DPP4/CCL2/angiogenesis cascade had key roles in HFD-associated HCC progression. Furthermore, concomitant changes in serum DPP4 and CCL2 were observed in 210 patients with HCC, and high serum DPP4 activity was associated with poor clinical prognosis. These results revealed a link between obesity-related high serum DPP4 activity and HCC progression. Inhibition of DPP4 may represent a novel therapeutic intervention for patients with HCC.

Isolation and characterization of the primary epithelial breast cancer cells and the adjacent normal epithelial cells from Iranian women's breast cancer tumors

As an experimental model, most studies rely on established human cancer cell lines; however, some genetical or phenotypical differences exist between these cells and their original tumor. Therefore, primary cells isolated directly from tissue are believed to be more biologically relevant tools for studying human and animal biology. Here, we aimed to isolate primary epithelial cancer and normal cells from breast tumors of Iranian women, for the first time. Thus, we isolated the epithelial and fibroblast cells from biopsy samples of patients with breast cancer based on differential centrifugation followed by culture in selective media. Normal epithelial cells obtained from the tissue biopsy away from the core of the tumor, based on the pathological diagnosis. Flow cytometry analysis indicated the positive immunoreactivity of the isolated epithelial cells against CD24 and Epithelial Specific Antigen (ESA/EpCAM), while they displayed a concomitant low expression of CD44 and CD49f. In contrat to fibroblasts, the qPCR data indicated the expression of luminal intracellular cytokeratin (Ck18) in both normal and cancer epithelial cells, but there was no expression of myoepithelial/basal markers, CK5 and vimentin. The epithelial cancer cells were reactive to cytokeratin 19 (CK19) antibody, whereas the normal epithelial cells were not. The expression of calmodulin-like protein (CLP) was also lower in the cancer epithelial cells than in the normal ones. In conclusion, primary epithelial normal and cancer cells, in addition to the fibroblasts were isolated and characterized from breast tumor of Iranian patients; and CLP expression is suggested as a susceptibility marker for breast cancer screening.

The dual role of asporin in breast cancer progression

Asporin has been reported as a tumor suppressor in breast cancer, while asporin-activated invasion has been described in gastric cancer. According to our in silico search, high asporin expresion associates with significantly better relapse free survival (RFS) in patients with low-grade tumors but RFS is significantly worse in patients with grade 3 tumors. In line with other studies, we have confirmed asporin expression by RNA scope in situ hybridization in cancer associated fibroblasts. We have also found asporin expression in the Hs578T breast cancer cell line which we confirmed by quantitative RT-PCR and western blotting. From multiple testing, we found that asporin can be downregulated by bone morphogenetic protein 4 while upregulation may be facilited by serum-free cultivation or by three dimensional growth in stiff Alvetex scaffold. Downregulation by shRNA inhibited invasion of Hs578T as well as of CAFs and T47D cells. Invasion of asporin-negative MDA-MB-231 and BT549 breast cancer cells through collagen type I was enhanced by recombinant asporin. Besides other investigations, large scale analysis of aspartic acid repeat polymorphism will be needed for clarification of the asporin dual role in progression of breast cancer.

Overexpression of syndecan-1, MUC-1, and putative stem cell markers in breast cancer leptomeningeal metastasis: a cerebrospinal fluid flow cytometry study

Background

Cancer is a mosaic of tumor cell subpopulations, where only a minority is responsible for disease recurrence and cancer invasiveness. We focused on one of the most aggressive circulating tumor cells (CTCs) which, from the primitive tumor, spreads to the central nervous system (CNS), evaluating the expression of prognostic and putative cancer stem cell markers in breast cancer (BC) leptomeningeal metastasis (LM).

Methods

Flow cytometry immunophenotypic analysis of cerebrospinal fluid (CSF) samples (4.5 ml) was performed in 13 consecutive cases of BCLM. Syndecan-1 (CD138), MUC-1 (CD227) CD45, CD34, and the putative cancer stem cell markers CD15, CD24, CD44, and CD133 surface expression were evaluated on CSF floating tumor cells. The tumor-associated leukocyte population was also characterized.

Results

Despite a low absolute cell number (8 cell/μl, range 1–86), the flow cytometry characterization was successfully conducted in all the samples. Syndecan-1 and MUC-1 overexpression was documented on BC cells in all the samples analyzed; CD44, CD24, CD15, and CD133 in 77%, 75%, 70%, and 45% of cases, respectively. A strong syndecan-1 and MUC-1 expression was also documented by immunohistochemistry on primary breast cancer tissues, performed in four patients. The CSF tumor population was flanked by T lymphocytes, with a different immunophenotype between the CSF and peripheral blood samples (P ≤ 0.02).

Conclusions

Flow cytometry can be successfully employed for solid tumor LM characterization even in CSF samples with low cell count. This in vivo study documents that CSF floating BC cells overexpress prognostic and putative cancer stem cell biomarkers related to tumor invasiveness, potentially representing a molecular target for circulating tumor cell detection and LM treatment monitoring, as well as a primary target for innovative treatment strategies. The T lymphocyte infiltration, documented in all CSF samples, suggests a possible involvement of the CNS lymphatic system in both lymphoid and cancer cell migration into and out of the meninges, supporting the extension of a new form of cellular immunotherapy to LM. Due to the small number of cases, validation on large cohorts of patients are warranted to confirm these findings and to evaluate the impact and value of these results for diagnosis and management of LM.

Electronic supplementary material

The online version of this article (doi:10.1186/s13058-017-0827-4) contains supplementary material, which is available to authorized users.

CD164 identifies CD4+ T cells highly expressing genes associated with malignancy in Sézary syndrome: the Sézary signature genes, FCRL3, Tox, and miR-214

Sézary syndrome (SS), a leukemic variant of cutaneous T-cell lymphoma (CTCL), is associated with a significantly shorter life expectancy compared to skin-restricted mycosis fungoides. Early diagnosis of SS is, therefore, key to achieving enhanced therapeutic responses. However, the lack of a biomarker(s) highly specific for malignant CD4+ T cells in SS patients has been a serious obstacle in making an early diagnosis. We recently demonstrated the high expression of CD164 on CD4+ T cells from Sézary syndrome patients with a wide range of circulating tumor burdens. To further characterize CD164 as a potential biomarker for malignant CD4+ T cells, CD164+ and CD164-CD4+ T cells isolated from patients with high-circulating tumor burden, B2 stage, and medium/low tumor burden, B1-B0 stage, were assessed for the expression of genes reported to differentiate SS from normal controls, and associated with malignancy and poor prognosis. The expression of Sézary signature genes: T plastin, GATA-3, along with FCRL3, Tox, and miR-214, was significantly higher, whereas STAT-4 was lower, in CD164+ compared with CD164-CD4+ T cells. While Tox was highly expressed in both B2 and B1-B0 patients, the expression of Sézary signature genes, FCRL3, and miR-214 was associated predominantly with advanced B2 disease. High expression of CD164 mRNA and protein was also detected in skin from CTCL patients. CD164 was co-expressed with KIR3DL2 on circulating CD4+ T cells from high tumor burden SS patients, further providing strong support for CD164 as a disease relevant surface biomarker.

Immunophenotyping and Transcriptomic Outcomes in PDX-Derived TNBC Tissue

Cancer tissue functions as an ecosystem of a diverse set of cells that interact in a complex tumor microenvironment. Genomic tools applied to biopsies in bulk fail to account for this tumor heterogeneity, whereas single-cell imaging methods limit the number of cells which can be assessed or are very resource intensive. The current study presents methods based on flow cytometric analysis and cell sorting using known cell surface markers (CXCR4/CD184, CD24, THY1/CD90) to identify and interrogate distinct groups of cells in triple-negative breast cancer clinical biopsy specimens from patient-derived xenograft (PDX) models. The results demonstrate that flow cytometric analysis allows a relevant subgrouping of cancer tissue and that sorting of these subgroups provides insights into cancer cell populations with unique, reproducible, and functionally divergent gene expression profiles. The discovery of a drug resistance signature implies that uncovering the functional interaction between these populations will lead to deeper understanding of cancer progression and drug response.Implications: PDX-derived human breast cancer tissue was investigated at the single-cell level, and cell subpopulations defined by surface markers were identified which suggest specific roles for distinct cellular compartments within a solid tumor. Mol Cancer Res; 15(4); 429-38. ©2016 AACR.

CD26 a cancer stem cell marker and therapeutic target

Cancer stem cells (CSCs) comprise a tumor subpopulation responsible for tumor maintenance, resistance to chemotherapy, recurrence and metastasis. The identification of this cell group is very important, but there is still no consensus on its characterization. Several CSC markers have been described, like CD133, CD24, CD44 and ALDH1, but more research to identify new markers to facilitate the identification of CSC in a heterogeneous tumoral mass is required. Thus, this article describes the CD26 expression as a CSC marker and the role that it plays in different types of cancer. CD26 expression correlates with some characteristics of CSCs, like the formation of spheres in vitro, formation of new tumors, and resistance to chemotherapy. CD26 is therefore suggested as an auxiliary marker for CSC in different types of cancer, and as a potential therapeutic target.

Arsenic-induced sub-lethal stress reprograms human bronchial epithelial cells to CD61¯ cancer stem cells

In the present report, we demonstrate that sub-lethal stress induced by consecutive exposure to 0.25 μM arsenic (As³⁺) for six months can trigger reprogramming of the human bronchial epithelial cell (BEAS-2B) to form cancer stem cells (CSCs) without forced introduction of the stemness transcription factors. These CSCs formed from As³⁺-induced sub-lethal stress featured with an increased expression of the endogenous stemness genes, including Oct4, Sox2, Klf4, Myc, and others that are associated with the pluripotency and self-renewal of the CSCs. Flow cytometry analysis indicated that 90% of the CSC cells are CD61¯, whereas 100% of the parental cells are CD61⁺. These CD61¯ CSCs are highly tumorigenic and metastatic to the lung in xenotransplantation tests in NOD/SCID Il2rγ^−/− mice. Additional tests also revealed that the CD61¯ CSCs showed a significant decrease in the expression of the genes important for DNA repair and oxidative phosphorylation. To determine the clinical relevance of the above findings, we stratified human lung cancers based on the level of CD61 protein and found that CD61^low cancer correlates with poorer survival of the patients. Such a correlation was also observed in human breast cancer and ovarian cancer. Taken together, our findings suggest that in addition to the traditional approaches of enforced introduction of the exogenous stemness circuit transcription factors, sub-lethal stress induced by consecutive low dose As³⁺ is also able to convert non-stem cells to the CSCs.

Inhibition of Hedgehog signalling by NVP-LDE225 (Erismodegib) interferes with growth and invasion of human renal cell carcinoma cells

Background:

Multiple lines of evidence support that the Hedgehog (Hh) signalling has a role in the maintenance and progression of different human cancers. Therefore, inhibition of the Hh pathway represents a valid anticancer therapeutic approach for renal cell carcinoma (RCC) patients. NVP-LDE225 is a Smoothened (Smo) antagonist that induces dose-related inhibition of Hh and Smo-dependent tumour growth.

Methods:

We assayed the effects of NVP-LDE225 alone or in combination with everolimus or sunitinib on the growth and invasion of human RCC models both in vitro and in vivo. To this aim, we used a panel of human RCC models, comprising cells with acquired resistance to sunitinib – a multiple tyrosine kinase inhibitor approved as a first-line treatment for RCC.

Results:

NVP-LDE225 cooperated with either everolimus or sunitinib to inhibit proliferation, migration, and invasion of RCC cells even in sunitinib-resistant (SuR) cells. Some major transducers involved in tumour cell motility, including paxillin, were also efficiently inhibited by the combination therapy, as demonstrated by western blot and confocal microscopy assays. Moreover, these combined treatments inhibited tumour growth and increased animal survival in nude mice xenografted with SuR RCC cells. Finally, lung micrometastasis formation was reduced when mice were treated with NVP-LDE225 plus everolimus or sunitinib, as evidenced by artificial metastatic assays.

Conclusions:

Hedgehog inhibition by NVP-LDE225 plus sunitinib or everolimus bolsters antitumour activity by interfering with tumour growth and metastatic spread, even in SuR cells. Thus, this new evidence puts forward a new promising therapeutic approach for RCC patients.

The dog as a natural animal model for study of the mammary myoepithelial basal cell lineage and its role in mammary carcinogenesis

Basal-like tumours constitute 2-18% of all human breast cancers (HBCs). These tumours have a basal myoepithelial phenotype and it has been hypothesized that they originate from either myoepithelial cells or mammary progenitor cells. They are heterogeneous in morphology, clinical presentation, outcome and response to therapy. Canine mammary carcinomas (CMCs) have epidemiological and biological similarities to HBCs, are frequently biphasic and are composed of two distinct neoplastic populations (epithelial and myoepithelial). The present study evaluates the potential of CMCs as a natural model for basal-like HBCs. Single and double immunohistochemistry was performed on serial sections of 10 normal canine mammary glands and 65 CMCs to evaluate expression of cytokeratin (CK) 8/18, CK5, CK14, α-smooth muscle actin (SMA), calponin (CALP), p63 and vimentin (VIM). The tumours were also evaluated for Ki67 and human epidermal growth factor receptor (HER)-2 expression. A hierarchical model of cell differentiation was established, similar to that for the human breast. We hypothesized that progenitor cells (CK5(+), CK14(+), p63(+) and VIM(+)) differentiate into terminally-differentiated luminal glandular (CK8/18(+)) and myoepithelial (CALP(+), SMA(+) and VIM(+)) cells via intermediary luminal glandular cells (CK5(+), CK14(+) and CK8/CK18(+)) and intermediary myoepithelial cells (CK5(+), CK14(+), p63(+), SMA(+), CALP(+) and VIM(+)). Neoplastic myoepithelial cells in canine complex carcinomas had labelling similar to that of terminally-differentiated myoepithelial cells, while those of carcinomas-and-malignant myoepitheliomas with a more aggressive biological behaviour (i.e. higher frequency of vascular/lymph node invasion and visceral metastases and higher risk of tumour-related death) were comparable with intermediary myoepithelial cells and had significantly higher Ki67 expression. The majority of CMCs examined were negative for expression of HER-2. The biphasic appearance of CMCs with involvement of the myoepithelial component in different stages of cell differentiation may help to define the role of myoepithelial cells in the mammary carcinogenetic process and the heterogeneous nature of basal-like HBCs.

Should EMT of Cancer Cells Be Understood as Epithelial-Myeloid Transition?

Cancer cells express epithelial markers, and when progressing in malignancy they may express markers of the mesenchymal cell type. Therefore an epithelial-mesenchymal transition of the cancer cells is assumed. However the mesenchymal markers can equally well be interpreted as myeloid markers since they are common in both types of cell lineages. Moreover, cancer cells express multiple specific markers of the myeloid lineages thus giving rise to the hypothesis that the transition of cancer cells may be from epithelial to myeloid cells and not to mesenchymal cells. This interpretation would better explain why cancer cells, often already in their primary cancer site, frequently show properties common to those of macrophages, platelets and pre-/osteoclasts.

Tetraspanin proteins promote multiple cancer stages

An abundance of evidence shows supporting roles for tetraspanin proteins in human cancer. Many studies show that the expression of tetraspanins correlates with tumour stage, tumour type and patient outcome. In addition, perturbations of tetraspanins in tumour cell lines can considerably affect cell growth, morphology, invasion, tumour engraftment and metastasis. This Review emphasizes new studies that have used de novo mouse cancer models to show that select tetraspanin proteins have key roles in tumour initiation, promotion and metastasis. This Review also emphasizes how tetraspanin proteins can sometimes participate in tumour angiogenesis. These recent data build an increasingly strong case for tetraspanins as therapeutic targets.

CD164 and FCRL3 are highly expressed on CD4+CD26- T cells in Sézary syndrome patients

Sézary syndrome (SS) cells express cell surface molecules also found on normal activated CD4 T cells. In an effort to find a more specific surface marker for malignant SS cells, a microarray analysis of gene expression was performed. Results showed significantly increased levels of mRNA for CD164, a sialomucin found on human CD34+ hematopoietic stem cells, and FCRL3, a molecule present on a subset of human natural T regulatory cells. Both markers were increased in CD4 T cells from SS patients compared to healthy donors. Flow cytometry studies confirmed the increased expression of CD164 and FCRL3 primarily on CD4+CD26− T cells of SS patients. Importantly, a statistically significant correlation was found between an elevated percentage of CD4+CD164+ T cells and an elevated percentage of CD4+CD26− T cells in all tested SS patients but not in patients with Mycosis Fungoides and atopic dermatitis or healthy donors. FCRL3 expression was significantly increased only in high tumor burden patients. CD4+CD164+ cells displayed cerebriform morphology and their loss correlated with clinical improvement in treated patients. Our results suggest that CD164 can serve as a marker for diagnosis and for monitoring progression of CTCL/SS and that FCRL3 expression correlates with a high circulating tumor burden.

Dipeptidyl peptidase-4: A key player in chronic liver disease

Dipeptidyl peptidase-4 (DPP-4) is a membrane-associated peptidase, also known as CD26. DPP-4 has widespread organ distribution throughout the body and exerts pleiotropic effects via its peptidase activity. A representative target peptide is glucagon-like peptide-1, and inactivation of glucagon-like peptide-1 results in the development of glucose intolerance/diabetes mellitus and hepatic steatosis. In addition to its peptidase activity, DPP-4 is known to be associated with immune stimulation, binding to and degradation of extracellular matrix, resistance to anti-cancer agents, and lipid accumulation. The liver expresses DPP-4 to a high degree, and recent accumulating data suggest that DPP-4 is involved in the development of various chronic liver diseases such as hepatitis C virus infection, non-alcoholic fatty liver disease, and hepatocellular carcinoma. Furthermore, DPP-4 occurs in hepatic stem cells and plays a crucial role in hepatic regeneration. In this review, we described the tissue distribution and various biological effects of DPP-4. Then, we discussed the impact of DPP-4 in chronic liver disease and the possible therapeutic effects of a DPP-4 inhibitor.