CD44v6 engages in colorectal cancer progression

CD44: a cancer stem cell marker and therapeutic target in leukemia treatment

CD44 is a ubiquitous leukocyte adhesion molecule involved in cell-cell interaction, cell adhesion, migration, homing and differentiation. CD44 can mediate the interaction between leukemic stem cells and the surrounding extracellular matrix, thereby inducing a cascade of signaling pathways to regulate their various behaviors. In this review, we focus on the impact of CD44s/CD44v as biomarkers in leukemia development and discuss the current research and prospects for CD44-related interventions in clinical application.

Long noncoding RNA ABHD11-AS1 interacts with SART3 and regulates CD44 RNA alternative splicing to promote lung carcinogenesis

Hexavalent chromium [Cr(VI)] is a common environmental pollutant and chronic exposure to Cr(VI) causes lung cancer in humans, however, the mechanism of Cr(VI) carcinogenesis has not been well understood. Lung cancer is the leading cause of cancer-related death, although the mechanisms of how lung cancer develops and progresses have been poorly understood. While long non-coding RNAs (lncRNAs) are found abnormally expressed in cancer, how dysregulated lncRNAs contribute to carcinogenesis remains largely unknown. The goal of this study is to investigate the mechanism of Cr(VI)-induced lung carcinogenesis focusing on the role of the lncRNA ABHD11 antisense RNA 1 (tail to tail) (ABHD11-AS1). It was found that the lncRNA ABHD11-AS1 expression levels are up-regulated in chronic Cr(VI) exposure-transformed human bronchial epithelial cells, chronically Cr(VI)-exposed mouse lung tissues, and human lung cancer cells as well. Bioinformatics analysis revealed that ABHD11-AS1 levels are up-regulated in lung adenocarcinomas (LUADs) tissues and associated with worse overall survival of LUAD patients but not in lung squamous cell carcinomas. It was further determined that up-regulation of ABHD11-AS1 expression plays an important role in chronic Cr(VI) exposure-induced cell malignant transformation and tumorigenesis, and the stemness of human lung cancer cells. Mechanistically, it was found that ABHD11-AS1 directly binds SART3 (spliceosome associated factor 3, U4/U6 recycling protein). The interaction of ABHD11-AS1 with SART3 promotes USP15 (ubiquitin specific peptidase 15) nuclear localization. Nuclear localized USP15 interacts with pre-mRNA processing factor 19 (PRPF19) to increase CD44 RNA alternative splicing activating β-catenin and enhancing cancer stemness. Together, these findings indicate that lncRNA ABHD11-AS1 interacts with SART3 and regulates CD44 RNA alternative splicing to promote cell malignant transformation and lung carcinogenesis.

Novel Therapeutic Approaches for Colorectal Cancer Treatment

According to GLOBOCAN 2020 data, colorectal cancer (CRC) represents the third most common malignancy and the second most deadly cancer worldwide [...].

CAR-T cell immunotherapy for ovarian cancer: hushing the silent killer

As the most lethal gynecologic oncological indication, carcinoma of the ovary has been ranked as the 5th cause of cancer-related mortality in women, with a high percentage of the patients being diagnosed at late stages of the disease and a five-year survival of ~ 30%. Ovarian cancer patients conventionally undergo surgery for tumor removal followed by platinum- or taxane-based chemotherapy; however, a high percentage of patients experience tumor relapse. Cancer immunotherapy has been regarded as a silver lining in the treatment of patients with various immunological or oncological indications; however, mirvetuximab soravtansine (a folate receptor α-specific mAb) and bevacizumab (a VEGF-A-specific mAb) are the only immunotherapeutics approved for the treatment of ovarian cancer patients. Chimeric antigen receptor T-cell (CAR-T) therapy has achieved tremendous clinical success in the treatment of patients with certain B-cell lymphomas and leukemias, as well as multiple myeloma. In the context of solid tumors, CAR-T therapies face serious obstacles that limit their therapeutic benefit. Such hindrances include the immunosuppressive nature of solid tumors, impaired tumor infiltration, lack of qualified tumor-associated antigens, and compromised stimulation and persistence of CAR-Ts following administration. Over the past years, researchers have made arduous attempts to apply CAR-T therapy to ovarian cancer. In this review, we outline the principles of CAR-T therapy and then highlight its limitations in the context of solid tumors. Ultimately, we focus on preclinical and clinical findings achieved in CAR-T-mediated targeting of different ovarian cancer-associated target antigens.

Metastasis suppressor genes in clinical practice: are they druggable?

Since the identification of NM23 (now called NME1) as the first metastasis suppressor gene (MSG), a small number of other gene products and non-coding RNAs have been identified that suppress specific parameters of the metastatic cascade, yet which have little or no ability to regulate primary tumor initiation or maintenance. MSG can regulate various pathways or cell biological functions such as those controlling mitogen-activated protein kinase pathway mediators, cell-cell and cell-extracellular matrix protein adhesion, cytoskeletal architecture, G-protein-coupled receptors, apoptosis, and transcriptional complexes. One defining facet of this gene class is that their expression is typically downregulated, not mutated, in metastasis, such that any effective therapeutic intervention would involve their re-expression. This review will address the therapeutic targeting of MSG, once thought to be a daunting task only facilitated by ectopically re-expressing MSG in metastatic cells in vivo. Examples will be cited of attempts to identify actionable oncogenic pathways that might suppress the formation or progression of metastases through the re-expression of specific metastasis suppressors.

LncRNA CCAT2 promotes malignant progression of metastatic gastric cancer through regulating CD44 alternative splicing

OBJECTIVE

Gastric cancer (GC) is one of the most malignant tumors worldwide. Thus, it is necessary to explore the underlying mechanisms of GC progression and develop novel therapeutic regimens. Long non-coding RNAs (lncRNAs) have been demonstrated to be abnormally expressed and regulate the malignant behaviors of cancer cells. Our previous research demonstrated that lncRNA colon cancer-associated transcript 2 (CCAT2) has potential value for GC diagnosis and discrimination. However, the functional mechanisms of lncRNA CCAT2 in GC development remain to be explored.

METHODS

GC and normal adjacent tissues were collected to detect the expression of lncRNA CCAT2, ESRP1 and CD44 in clinical specimens and their clinical significance for GC patients. Cell counting kit-8, wound healing and transwell assays were conducted to investigate the malignant behaviors in vitro. The generation of nude mouse xenografts by subcutaneous, intraperitoneal and tail vein injection was performed to examine GC growth and metastasis in vivo. Co-immunoprecipitation, RNA-binding protein pull-down assay and fluorescence in situ hybridization were performed to reveal the binding relationships between ESRP1 and CD44.

RESULTS

In the present study, lncRNA CCAT2 was overexpressed in GC tissues compared to adjacent normal tissues and correlated with short survival time of patients. lncRNA CCAT2 promoted the proliferation, migration and invasion of GC cells. Its overexpression modulates alternative splicing of Cluster of differentiation 44 (CD44) variants and facilitates the conversion from the standard form to variable CD44 isoform 6 (CD44v6). Mechanistically, lncRNA CCAT2 upregulated CD44v6 expression by binding to epithelial splicing regulatory protein 1 (ESRP1), which subsequently mediates CD44 alternative splicing. The oncogenic role of the lncRNA CCAT2/ESRP1/CD44 axis in the promotion of malignant behaviors was verified by both in vivo and in vitro experiments.

CONCLUSIONS

Our findings identified a novel mechanism by which lncRNA CCAT2, as a type of protein-binding RNA, regulates alternative splicing of CD44 and promotes GC progression. This axis may become an effective target for clinical diagnosis and treatment.

Cancer Stem Cells in Colorectal Cancer: Implications for Targeted Immunotherapies

PURPOSE

Colorectal cancers are composed of heterogeneous cell populations in the concepts of genetic and functional degrees that among them cancer stem cells are identified with their self-renewal and stemness capability mediating primary tumorigenesis, metastasize, therapeutic resistance, and tumor recurrence. Therefore, understanding the key mechanisms of stemness in colorectal cancer stem cells (CRCSCs) provides opportunities to discover new treatments or improve existing therapeutic regimens.

METHODS

We review the biological significance of stemness and the results of potential CRCSC-based targeted immunotherapies. Then, we pointed out the barriers to targeting CRCSCs in vivo and highlight new strategies based on synthetic and biogenic nanocarriers for the development of future anti-CRCSC trials.

RESULTS

The CSCs' surface markers, antigens, neoantigens, and signaling pathways supportive CRCSCs or immune cells that are interacted with CRCSCs could be targeted by immune monotherapy or in formulation with developed nanocarriers to overcome the resistant mechanisms in immune evader CRCSCs.

CONCLUSION

Identification molecular and cellular cues supporting stemness in CRCSCs and their targeting by nanoimmunotherpy can improve the efficacy of existed therapies or explore novel therapeutic options in future.

Is cancer an intelligent species?

Some relevant emerging properties of intelligent systems are "adaptation to a changing environment," "reaction to unexpected situations," "capacity of problem solving," and "ability to communicate." Single cells have remarkable abilities to adapt, make adequate context-dependent decision, take constructive actions, and communicate, thus theoretically meeting all the above-mentioned requirements. From a biological point of view, cancer can be viewed as an invasive species, composed of cells that move from primary to distant sites, being continuously exposed to changes in the environmental conditions. Blood represents the first hostile habitat that a cancer cell encounters once detached from the primary site, so that cancer cells must rapidly carry out multiple adaptation strategies to survive. The aim of this review was to deepen the adaptation mechanisms of cancer cells in the blood microenvironment, particularly referring to four adaptation strategies typical of animal species (phenotypic adaptation, metabolic adaptation, niche adaptation, and collective adaptation), which together define the broad concept of biological intelligence. We provided evidence that the required adaptations (either structural, metabolic, and related to metastatic niche formation) and "social" behavior are useful principles allowing putting into a coherent frame many features of circulating cancer cells. This interpretative frame is described by the comparison with analog behavioral traits typical of various animal models.

Selection, characterization and in vivo evaluation of novel CD44v6-targeting antibodies for targeted molecular radiotherapy

Molecular radiotherapy combines the advantages of systemic administration of highly specific antibodies or peptides and the localized potency of ionizing radiation. A potential target for molecular radiotherapy is the cell surface antigen CD44v6, which is overexpressed in numerous cancers, with limited expression in normal tissues. The aim of the present study was to generate and characterize a panel of human anti-CD44v6 antibodies and identify a suitable candidate for future use in molecular radiotherapy of CD44v6-expressing cancers. Binders were first isolated from large synthetic phage display libraries containing human scFv and Fab antibody fragments. The antibodies were extensively analyzed through in vitro investigations of binding kinetics, affinity, off-target binding, and cell binding. Lead candidates were further subjected to in vivo biodistribution studies in mice bearing anaplastic thyroid cancer xenografts that express high levels of CD44v6. Additionally, antigen-dependent tumor uptake of the lead candidate was verified in additional xenograft models with varying levels of target expression. Interestingly, although only small differences were observed among the top antibody candidates in vitro, significant differences in tumor uptake and retention were uncovered in in vivo experiments. A high-affinity anti-CD44v6 lead drug candidate was identified, mAb UU-40, which exhibited favorable target binding properties and in vivo distribution. In conclusion, a panel of human anti-CD44v6 antibodies was successfully generated and characterized in this study. Through comprehensive evaluation, mAb UU-40 was identified as a promising lead candidate for future molecular radiotherapy of CD44v6-expressing cancers due to its high affinity, excellent target binding properties, and desirable in vivo distribution characteristics.

Longitudinal detection of subcategorized CD44v6+ CTCs and circulating tumor endothelial cells (CTECs) enables novel clinical stratification and improves prognostic prediction of small cell lung cancer: A prospective, multi-center study

Current management of small cell lung cancer (SCLC) remains challenging. Effective biomarkers are needed to subdivide patients presenting distinct treatment response and clinical outcomes. An understanding of heterogeneous phenotypes of aneuploid CD31- circulating tumor cells (CTCs) and CD31+ circulating tumor endothelial cells (CTECs) may provide novel insights in the clinical management of SCLC. In the present translational and prospective study, increased cancer metastasis-related cell proliferation and motility, accompanied with up-regulated mesenchymal marker vimentin but down-regulated epithelial marker E-cadherin, were observed in both lentivirus infected SCLC and NSCLC cells overexpressing the stemness marker CD44v6. Aneuploid CTCs and CTECs expressing CD44v6 were longitudinally detected by SE-iFISH in 120 SCLC patients. Positive detection of baseline CD44v6+ CTCs and CD44v6+ CTECs was significantly associated with enhanced hepatic metastasis. Karyotype analysis revealed that chromosome 8 (Chr8) in CD44v6+ CTCs shifted from trisomy 8 towards multiploidy in post-therapeutic patients compared to pre-treatment subjects. Furthermore, the burden of baseline CD44v6+ CTCs (t0) or amid the therapy (t1-2), the ratio of baseline CD31+ CTEC/CD31- CTC (t0), and CTC-WBC clusters (t0) were correlated with treatment response and distant metastases, particularly brain metastasis, in subjects with limited disease (LD-SCLC) but not in those with extensive disease (ED-SCLC). Multivariate survival analysis validated that longitudinally detected CD44v6+/CD31- CTCs was an independent prognostic factor for inferior survival in SCLC patients. Our study provides evidence for the first time that comprehensive analyses of CTCs, CTECs, and their respective CD44v6+ subtypes enable clinical stratification and improve prognostic prediction of SCLC, particularly for potentially curable LD-SCLC.

Targeted splicing therapy: new strategies for colorectal cancer

RNA splicing is the process of forming mature mRNA, which is an essential phase necessary for gene expression and controls many aspects of cell proliferation, survival, and differentiation. Abnormal gene-splicing events are closely related to the development of tumors, and the generation of oncogenic isoform in splicing can promote tumor progression. As a main process of tumor-specific splicing variants, alternative splicing (AS) can promote tumor progression by increasing the production of oncogenic splicing isoforms and/or reducing the production of normal splicing isoforms. This is the focus of current research on the regulation of aberrant tumor splicing. So far, AS has been found to be associated with various aspects of tumor biology, including cell proliferation and invasion, resistance to apoptosis, and sensitivity to different chemotherapeutic drugs. This article will review the abnormal splicing events in colorectal cancer (CRC), especially the tumor-associated splicing variants arising from AS, aiming to offer an insight into CRC-targeted splicing therapy.

The clinical significance of CD44v6 in malignant and benign primary bone tumors

BACKGROUND

The objective of this study was to assess the expression profile of CD44v6, a potential cancer stem cell marker, and its diagnostic and predictive significance in three distinct types of primary bone tumors.

METHODS

In this study, we utilized real-time qRT-PCR and immunohistochemistry to examine the gene and protein levels of CD44v6 in a total of 138 fresh bone tissues. This included 69 tumor tissues comprising osteosarcoma (N = 23), chondrosarcoma (N = 23), and GCT (N = 23), as well as 69 corresponding non-cancerous tumor margins. Furthermore, we investigated the circulating level of CD44v6 by isolating peripheral blood mononuclear cells from 92 blood samples. Among these, 69 samples were obtained from patients diagnosed with primary bone tumors, while the remaining 23 samples were from healthy donors. The primary objectives of our investigation were to assess the correlation between CD44v6 expression levels and clinic-pathological features of the patients, as well as to evaluate the diagnostic and predictive values of CD44v6 in this context.

RESULTS

In patients with osteosarcoma and chondrosarcoma tumors, both the gene and protein expression of CD44v6 were found to be significantly higher compared to the GCT group. Furthermore, the circulating level of CD44v6 was notably elevated in patients diagnosed with osteosarcoma and chondrosarcoma in comparison to the GCT group and patients with malignant tumor characteristics. Additionally, we observed a strong correlation between the gene and protein levels of CD44v6 and important tumor indicators such as tumor grade, metastasis, recurrence, and size at the tumor site. CD44v6 shows potential in differentiating patients with bone tumors from both control groups and tumor groups with severe and invasive characteristics from those with non-severe features. Importantly, the expression level of CD44v6 also demonstrated predictive value for determining tumor grade and the likelihood of recurrence.

CONCLUSION

CD44v6 is likely to play a role in the development of primary bone tumors and has the potential to serve as a diagnostic biomarker for bone cancer. However, to obtain more accurate and conclusive findings, further mechanistic investigations involving larger population samples are necessary.

Cd44v6 acts as a directional responding factor in the process of transcoelomic metastasis from gastric carcinoma to Krukenberg tumor

INTRODUCTION

Due to the limited number of studies focusing on the optimal treatment of multiple Krukenberg tumor (KT)-gastric carcinoma (KT - GC), it is necessary to conduct large-scale studies to confirm the definite role of serum tumor markers in the diagnosis and prognosis of KT. Moreover, the clinical significance of variant 6 of CD44 (CD44v6) in transcoelomic metastasis should be considered.

AREAS COVERED

This review covers molecular pre-cancer diagnosis, gastric carcinoma metastasis, and anti-cancer treatments. Additionally, gastrointestinal cancer metastasis is a key area for improvement.

EXPERT OPINION

The detection of CD44v6 differs in the World Health Organization Classification of Gastric Adenocarcinoma, the Lauren Classification of Gastric Adenocarcinoma, and the anatomic location of gastric adenocarcinoma. The results were compared among the three groups. The mechanism of gastric adenocarcinoma metastasis still requires further elucidation. CD44v6 molecular detection helps clarify the pre-cancer diagnosis of KT before seeding. If subsequent studies confirm its role as a signaling molecule, it could pave the way for new research directions in clinical practice; however, additional academic confirmation is necessary.

The prognostic value and immunological role of CD44 in pan-cancer study

To investigate the correlation between cluster of differentiation-44 (CD44) expression and immunotherapy response and identify its possible predictive value in pan-cancer. Datasets of 33 cancer types from The Cancer Genome Atlas (TCGA) database were applied to investigate the relationship of CD44 expression with prognosis, tumor mutational burden (TMB), and microsatellite instability (MSI), and determine its potential prognostic value in pan-cancer. Patients were split into high-risk and low-risk cancer groups based on the survival outcomes of various cancer types. Additionally, the underlying mechanisms of CD44 in the tumor microenvironment (TME) were analyzed using ESTIMATE and CIBERSORT algorithms and Gene Set Enrichment Analysis (GSEA). Subsequently, the biological role of CD44 at single-cell level was investigated using CancerSEA database. Variable expression levels of CD44 between tumor and adjacent normal tissues were identified in pan-cancer datasets, further survival analysis revealed that CD44 expression was associated with multiple clinical annotations and survival indicators. Besides, the expression of CD44 was significantly associated with TMB and MSI in 10 types and 6 types of cancer, respectively, indicating it could be exploited as a potential biomarker predicting immunotherapy outcomes. Meanwhile, CD44 could influence several crucial immune cell-related pathways. and the results revealed by CancerSEA database denoted the correlation of CD44 with malignant phenotype and functional states, further indicating it can serve as a potential therapeutic target in cancer management. Our study demonstrated that CD44 shows great promise as a prognostic biomarker in numerous cancers, which will assist in developing new strategies in cancer management.

Differential methylation in CD44 and SEC23A is associated with time preference in older individuals

Time preference is a measure used to ascertain the level of which individuals prefer smaller, immediate rewards over larger, delayed rewards. We explored how an individual's time preference associates with their epigenetic profile. Time preferences were ascertained by asking participants of the Northern Ireland COhort for the Longitudinal study of Ageing to make a series of choices between two hypothetical income scenarios. From these, eight 'time preference' categories were derived, ranging from "patient" to "impatient" on an ordinal scale. The Infinium High Density Methylation Assay, MethylationEPIC (Illumina) was used to evaluate the status of 862,927 CpGs. Time preference and DNA methylation data were obtained for 1648 individuals. Four analyses were conducted, assessing the methylation patterns at single site resolution between patient and impatient individuals using two adjustment models. In this discovery cohort analysis, two CpG sites were identified with significantly different levels of methylation (p < 9 × 10^-8) between the individuals allocated to the patient group and the remaining population following adjustment for covariates; cg08845621 within CD44 and cg18127619 within SEC23A. Neither of these genes have previously been linked to time preference. Epigenetic modifications have not previously been linked to time preference using a population cohort but they may represent important biomarkers of accumulated, complex determinants of this trait. Further analysis is warranted of both the top-ranked results and of DNA methylation as an important link between measurable biomarkers and health behaviours.

Preclinical and Clinical Trials of New Treatment Strategies Targeting Cancer Stem Cells in Subtypes of Breast Cancer

Breast cancer (BC) can be classified into various histological subtypes, each associated with different prognoses and treatment options, including surgery, radiation, chemotherapy, and endocrine therapy. Despite advances in this area, many patients still face treatment failure, the risk of metastasis, and disease recurrence, which can ultimately lead to death. Mammary tumors, like other solid tumors, contain a population of small cells known as cancer stem-like cells (CSCs) that have high tumorigenic potential and are involved in cancer initiation, progression, metastasis, tumor recurrence, and resistance to therapy. Therefore, designing therapies specifically targeting at CSCs could help to control the growth of this cell population, leading to increased survival rates for BC patients. In this review, we discuss the characteristics of CSCs, their surface biomarkers, and the active signaling pathways associated with the acquisition of stemness in BC. We also cover preclinical and clinical studies that focus on evaluating new therapy systems targeted at CSCs in BC through various combinations of treatments, targeted delivery systems, and potential new drugs that inhibit the properties that allow these cells to survive and proliferate.

Development of a Novel Anti-CD44 Variant 6 Monoclonal Antibody C44Mab-9 for Multiple Applications against Colorectal Carcinomas

CD44 is a cell surface glycoprotein, and its isoforms are produced by the alternative splicing with the standard and variant exons. The CD44 variant exon-containing isoforms (CD44v) are overexpressed in carcinomas. CD44v6 is one of the CD44v, and its overexpression predicts poor prognosis in colorectal cancer (CRC) patients. CD44v6 plays critical roles in CRC adhesion, proliferation, stemness, invasiveness, and chemoresistance. Therefore, CD44v6 is a promising target for cancer diagnosis and therapy for CRC. In this study, we established anti-CD44 monoclonal antibodies (mAbs) by immunizing mice with CD44v3-10-overexpressed Chinese hamster ovary (CHO)-K1 cells. We then characterized them using enzyme-linked immunosorbent assay, flow cytometry, western blotting, and immunohistochemistry. One of the established clones (C₄₄Mab-9; IgG₁, kappa) reacted with a peptide of the variant 6-encoded region, indicating that C₄₄Mab-9 recognizes CD44v6. Furthermore, C₄₄Mab-9 reacted with CHO/CD44v3-10 cells or CRC cell lines (COLO201 and COLO205) by flow cytometry. The apparent dissociation constant (K_D) of C₄₄Mab-9 for CHO/CD44v3-10, COLO201, and COLO205 was 8.1 × 10^-9 M, 1.7 × 10^-8 M, and 2.3 × 10^-8 M, respectively. C₄₄Mab-9 detected the CD44v3-10 in western blotting, and partially stained the formalin-fixed paraffin-embedded CRC tissues in immunohistochemistry. Collectively, C₄₄Mab-9 is useful for detecting CD44v6 in various applications.

The state of CD44 activation in cancer progression and therapeutic targeting

CD44, a non-kinase transmembrane glycoprotein, is ubiquitously expressed on various types of cells, especially cancer stem cells (CSCs), and has been implicated in cancer onset and aggressiveness. The major ligand for the CD44, hyaluronan (HA), binds to and interacts with CD44, which in turn triggers downstream signaling cascades, thereby promoting cellular behaviors such as proliferation, motility, invasiveness and chemoresistance. The CD44-HA interaction is cell-specific and strongly affected by the state of CD44 activation. Therefore, the binding of HA to CD44 is essential for the activation of CD44 during which the detailed regulatory mechanism needs to be clarified. Different CD44 activation states distribute in human carcinoma and normal tissue; however, whether CD44 activation is a critical requirement for tumor initiation, progression and notorious CSC properties remains to be clarified. A deeper understanding of the regulation of CD44 activation may facilitate the development of novel targeted drugs in the future. Here, we review the current findings concerning the states of CD44 activation on the cell surface, the underlying regulatory mechanisms of CD44 activation, the known role for CD44 activation in tumor progression and CSC hallmarks, as well as the potential of HA-coated nanoparticle for targeting activated CD44 for cancer therapy.

MiR-1246 is responsible for lung cancer cells-derived exosomes-mediated promoting effects on lung cancer stemness via targeting TRIM17

The stemness of lung cancer cells contributes to drug resistance, tumor occurrence, progression, and recurrence; however, the underlying mechanisms are still fragmentary. In the present study, it was found that exosomes from cisplatin-resistant cells and spheres derived from lung cancer cells enhanced the stemness of the parental lung cancer cells. Then we screened the upregulated miRNAs in spheres derived from lung cancer cells and cisplatin-resistant lung cancer cells/exosomes compared to that in the parental lung cancer cells. It was found that miR-1246 was remarkably enriched in cisplatin-resistant lung cancer cells/exosomes and spheres. Additionally, inhibition of miR-1246 attenuated the stemness of lung cancer cells induced by exosomes from cisplatin-resistant cells and spheres. Furthermore, TRIM17 was identified to the direct target of miR-1246 in lung cancer cells. Our findings suggest that exosomal miR-1246 could be as a potential target for lung cancer treatment.

CD44 Glycosylation as a Therapeutic Target in Oncology

The interaction of non-kinase transmembrane glycoprotein CD44 with ligands including hyaluronic acid (HA) is closely related to the occurrence and development of tumors. Changes in CD44 glycosylation can regulate its binding to HA, Siglec-15, fibronectin, TM4SF5, PRG4, FGF2, collagen and podoplanin and activate or inhibit c-Src/STAT3/Twist1/Bmi1, PI3K/AKT/mTOR, ERK/NF-κB/NANOG and other signaling pathways, thereby having a profound impact on the tumor microenvironment and tumor cell fate. However, the glycosylation of CD44 is complex and largely unknown, and the current understanding of how CD44 glycosylation affects tumors is limited. These issues must be addressed before targeted CD44 glycosylation can be applied to treat human cancers.

KS10076, a chelator for redox-active metal ions, induces ROS-mediated STAT3 degradation in autophagic cell death and eliminates ALDH1+ stem cells

Redox-active metal ions are pivotal for rapid metabolism, proliferation, and aggression across cancer types, and this presents metal chelation as an attractive cancer cell-targeting strategy. Here, we identify a metal chelator, KS10076, as a potent anti-cancer drug candidate. A metal-bound KS10076 complex with redox potential for generating hydrogen peroxide and superoxide anions induces intracellular reactive oxygen species (ROS). The elevation of ROS by KS10076 promotes the destabilization of signal transducer and activator of transcription 3, removes aldehyde dehydrogenase isoform 1-positive cancer stem cells, and subsequently induces autophagic cell death. Bioinformatic analysis of KS10076 susceptibility in pan-cancer cells shows that KS10076 potentially targets cancer cells with increased mitochondrial function. Furthermore, patient-derived organoid models demonstrate that KS10076 efficiently represses cancer cells with active KRAS, and fluorouracil resistance, which suggests clinical advantages.

SFPQ Promotes Lung Cancer Malignancy via Regulation of CD44 v6 Expression

Mesenchymal stem cells (MSCs) contribute to tumor pathogenesis and elicit antitumor immune responses in tumor microenvironments. Nuclear proteins might be the main players in these processes. In the current study, combining spatial proteomics with ingenuity pathway analysis (IPA) in lung non-small cell (NSC) cancer MSCs, we identify a key nuclear protein regulator, SFPQ (Splicing Factor Proline and Glutamine Rich), which is overexpressed in lung cancer MSCs and functions to promote MSCs proliferation, chemical resistance, and invasion. Mechanistically, the knockdown of SFPQ reduces CD44v6 expression to inhibit lung cancer MSCs stemness, proliferation in vitro, and metastasis in vivo. The data indicates that SFPQ may be a potential therapeutic target for limiting growth, chemotherapy resistance, and metastasis of lung cancer.

Role of CD44 isoforms in epithelial-mesenchymal plasticity and metastasis

Cellular plasticity lies at the core of cancer progression, metastasis, and resistance to treatment. Stemness and epithelial-mesenchymal plasticity in cancer are concepts that represent a cancer cell's ability to coopt and adapt normal developmental programs to promote survival and expansion. The cancer stem cell model states that a small subset of cancer cells with stem cell-like properties are responsible for driving tumorigenesis and metastasis while remaining especially resistant to common chemotherapeutic drugs. Epithelial-mesenchymal plasticity describes a cancer cell's ability to transition between epithelial and mesenchymal phenotypes which drives invasion and metastasis. Recent research supports the existence of stable epithelial/mesenchymal hybrid phenotypes which represent highly plastic states with cancer stem cell characteristics. The cell adhesion molecule CD44 is a widely accepted marker for cancer stem cells, and it lies at a functional intersection between signaling networks regulating both stemness and epithelial-mesenchymal plasticity. CD44 expression is complex, with alternative splicing producing many isoforms. Interestingly, not only does the pattern of isoform expression change during transitions between epithelial and mesenchymal phenotypes in cancer, but these isoforms have distinct effects on cell behavior including the promotion of metastasis and stemness. The role of CD44 both downstream and upstream of signaling pathways regulating epithelial-mesenchymal plasticity and stemness make this protein a valuable target for further research and therapeutic intervention.

Evaluation of CD44s, CD44v6, CXCR2, CXCL1, and IL-1β in Benign and Malignant Tumors of Salivary Glands

BACKGROUND

Several studies have reported an association between high expression of CD44 in different types of cancer. However, no study has reported a link among CD44 expression, other biomarkers, and the aggressiveness of salivary gland tumors.

METHODS

A total of 38 specimens were obtained from non-tumorous salivary glands, benign and malignant tumors in salivary glands. Immunohistochemical analyses of CD44s, CD44v6, IL-1β, CXCL1, and CXCR2 were performed, and the area of positive cells was assessed.

RESULTS

We found that both CD44s and CXCR2 expression were increased in the benign and malignant groups. CD44v6 was also increased in both groups, but it had the highest level in the malignant group. IL-1β was the only biomarker that increased significantly in the malignant group in comparison to the other two groups.

CONCLUSIONS

CD44s, CD44v6, CXCR2, and IL-1β expressions were found to be higher in salivary gland tumors. However, IL-1β alone may play a crucial role in the aggressiveness of salivary gland tumors as this cytokine was expressed only in the malignant group with high expression associated with high-grade malignancy.

Implication of Different Tumor Biomarkers in Drug Resistance and Invasiveness in Primary and Metastatic Colorectal Cancer Cell Lines

Protein expression profiles are directly related to the different properties of cells and are conditioned by the cellular niche. As an example, they are the cause of the characteristic cell plasticity, epithelium-mesenchymal transition (EMT), and drug resistance of cancer cells. This article characterizes ten biomarkers related to these features in three human colorectal cancer cell lines: SW-480, SW-620, and DLD-1, evaluated by flow cytometry; and in turn, resistance to oxaliplatin is studied through dose-response trials. The main biomarkers present in the three studied lines correspond to EpCAM, CD-133, and AC-133, with the latter two in low proportions in the DLD-1 line. The biomarker CD166 is present in greater amounts in SW-620 and DLD-1 compared to SW-480. Finally, DLD-1 shows high values of Trop2, which may explain the aggressiveness and resistance of these cells to oxaliplatin treatments, as EpCAM is also highly expressed. Exposure to oxaliplatin slows cell growth but also helps generate resistance to the treatment. In conclusion, the response of the cell lines is variable, due to their genetic variability, which will condition protein expression and cell growth. Further analyses in this area will provide important information for better understanding of patients' cellular response and how to prevent resistance.

Role of endoplasmic reticulum stress in apoptosis induced by HK2 inhibitor and its potential as a new drug combination strategy

Compared with normal cells, tumor cells mainly obtain energy through aerobic glycolysis. Hexokinase 2 (HK2) plays a key role in the regulation of tumor cell aerobic glycolysis, and targeting HK2 has become a new strategy for cancer treatment. However, little is known about the role of HK2 in colon cancer and the regulation of its targeted inhibitors. In this study, we found that the expression of HK2 in colorectal cancer tissues was significantly higher than that in adjacent tissues, and the expression level of HK2 in metastatic colorectal cancer was further increased. Meanwhile, the expression level of HK2 was closely related to clinical TNM stage and outcome of colorectal cancer patients. We provide here evidence that HK2 inhibitor 3-Bromopyruvate acid (3-BP) can significantly inhibit the survival and proliferation of colon cancer cells, and induce apoptosis through mitochondrial apoptosis signaling pathway. In addition, we found that 3-BP can also induce endoplasmic reticulum stress in colon cancer cells, the mechanism may be through the increase of intracellular calcium concentration. In vitro and in vivo experiments showed that inhibition of endoplasmic reticulum stress could further increase the proliferation inhibition and apoptosis induced by 3-BP. Collectively, our results show that HK2 is highly expressed in colorectal cancer. 3-BP, an inhibitor of HK2, can induce apoptosis and endoplasmic reticulum stress in colon cancer cells. Endoplasmic reticulum stress plays a protective role in cell death induced by 3-BP. This result suggested that targeting HK2 and endoplasmic reticulum stress may be a valuable strategy in targeted and combination therapy of colon cancer.

High Dual Expression of the Biomarkers CD44v6/α2β1 and CD44v6/PD-L1 Indicate Early Recurrence after Colorectal Hepatic Metastasectomy

Considering the biology of CRC, distant metastases might support the identification of high-risk patients for early recurrence and targeted therapy. Expression of a panel of druggable, metastasis-related biomarkers was immunohistochemically analyzed in 53 liver (LM) and 15 lung metastases (LuM) and correlated with survival. Differential expression between LM and LuM was observed for the growth factor receptors IGF1R (LuM 92.3% vs. LM 75.8%, p = 0.013), EGFR (LuM 68% vs. LM 41.5%, p = 0.004), the cell adhesion molecules CD44v6 (LuM 55.7% vs. LM 34.9%, p = 0.019) and α2β1 (LuM 88.3% vs. LM 58.5%, p = 0.001) and the check point molecule PD-L1 (LuM 6.1% vs. LM 3.3%, p = 0.005). Contrary, expression of HGFR, Hsp90, Muc1, Her2/neu, ERα and PR was comparable in LuM and LM. In the LM cohort (n = 52), a high CD44v6 expression was identified as an independent factor of poor prognosis (PFS: HR 2.37, 95% CI 1.18-4.78, p = 0.016). High co-expression of CD44v6/α2β1 (HR 4.14, 95% CI 1.65-10.38, p = 0.002) and CD44v6/PD-L1 (HR 2.88, 95% CI 1.21-6.85, p = 0.017) indicated early recurrence after hepatectomy, in a substantial number of patients (CD44v6/α2β1: 11 (21.15%) patients; CD44v6/PD-L1: 12 (23.1%) patients). Dual expression of druggable protein biomarkers may refine prognostic prediction and stratify high-risk patients for new therapeutic concepts, depending on the metastatic location.

CD44-Targeted Nanocarrier for Cancer Therapy

Cluster of differentiation 44 (CD44) is a cell surface glycoprotein overexpressed in varieties of solid tumors including pancreatic, breast, ovary, brain, and lung cancers. It is a multi-structural glycoprotein of the cell surface which is majorly involved in cell proliferation, cell-to-cell interaction, cellular migration, inflammation, and generation of immune responses. Numerous studies focus on the development of nanocarriers for active targeting of the CD44 receptor to improve efficacy of targeting chemotherapy and achieve precise chemotherapy by defining the release, uptake, and accumulation of therapeutic agents. The CD44 receptor has a selective binding affinity towards hyaluronic and chondroitin sulfate (CS). Taking this into consideration, this review focused on the role of CD44 in cancer and its therapy using several nanocarriers such as polymeric/non-polymeric nanoparticles, dendrimer, micelles, carbon nanotubes, nanogels, nanoemulsions etc., for targeted delivery of several chemotherapeutic molecules and nucleic acid. This review also illuminates the role of hyaluronic acid (HA) in cancer therapy, interaction of HA with CD44, and various approaches to target CD44-overexpressed neoplastic cells.

Hyaluronic Acid-Zein Core-Shell Nanoparticles Improve the Anticancer Effect of Curcumin Alone or in Combination with Oxaliplatin against Colorectal Cancer via CD44-Mediated Cellular Uptake

Curcumin (CUR) has been reported to enhance the chemotherapeutic efficacy of oxaliplatin (OXA) in colorectal cancer (CRC) and inhibit OXA-induced side effects. However, shortcomings, including poor solubility and sensitivity to metabolic transformation, have greatly undermined its value in clinical applications. In this study, the potential of CUR-encapsulated hyaluronic acid (HA)-zein composite nanoparticles (HZ-CUR) as an oral adjuvant for OXA-based chemotherapy was assessed in representative CRC models in mice. Cell viability and colony formation assays in three human CRC cell lines showed that HZ-CUR had a stronger anti-CRC effect than free CUR when given alone and a stronger synergistic effect when combined with OXA, especially in HCT116 and HT29 cell lines. Western blotting, cellular uptake, and RNA interference assays revealed that OXA-induced upregulation of CD44 likely contributed to enhanced cellular uptake of HZ-CUR and thus the enhanced anticancer effect. The significantly improved anti-CRC effects and potential underlying mechanism of HZ-CUR alone and in combination with OXA were further validated in a subcutaneous xenograft and an in situ CRC model in mice. These findings support that HZ-CUR may be an effective oral adjuvant for OXA-based CRC chemotherapy that would not only improve its efficacy but also help reduce the associated side effects.

Niclosamide induces miR-148a to inhibit PXR and sensitize colon cancer stem cells to chemotherapy

Tumor recurrence is often attributed to cancer stem cells (CSCs). We previously demonstrated that down-regulation of Pregnane X Receptor (PXR) decreases the chemoresistance of CSCs and prevents colorectal cancer recurrence. Currently, no PXR inhibitor is usable in clinic. Here, we identify miR-148a as a targetable element upstream of PXR signaling in CSCs, which when over-expressed decreases PXR expression and impairs tumor relapse after chemotherapy in mouse tumor xenografts. We then develop a fluorescent reporter screen for miR-148a activators and identify the anti-helminthic drug niclosamide as an inducer of miR-148a expression. Consequently, niclosamide decreased PXR expression and CSC numbers in colorectal cancer patient-derived cell lines and synergized with chemotherapeutic agents to prevent CSC chemoresistance and tumor recurrence in vivo. Our study suggests that endogenous miRNA inducers is a viable strategy to down-regulate PXR and illuminates niclosamide as a neoadjuvant repurposing strategy to prevent tumor relapse in colon cancer.

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miR-148a expression is decreased in colon cancer stem cells

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Forced expression of miR-148a inhibits colon cancer stem cell chemoresistance

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High-content screening identified niclosamide as a potent miR-148a inducer

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Niclosamide induces miR-148a expression, inhibits PXR expression in CSCs and prevents tumor

Identification of Circular RNA-Based Immunomodulatory Networks in Colorectal Cancer

BACKGROUND

Circular RNAs (circRNAs) have been recently proposed as hub molecules in various diseases, especially in tumours. We found that circRNAs derived from ribonuclease P RNA component H1 (RPPH1) were highly expressed in colorectal cancer (CRC) samples from Gene Expression Omnibus (GEO) datasets.

OBJECTIVE

We sought to identify new circRNAs derived from RPPH1 and investigate their regulation of the competing endogenous RNA (ceRNA) and RNA binding protein (RBP) networks of CRC immune infiltration.

METHODS

The circRNA expression profiles miRNA and mRNA data were extracted from the GEO and The Cancer Genome Atlas (TCGA) datasets, respectively. The differentially expressed (DE) RNAs were identified using R software and online server tools, and the circRNA-miRNA-mRNA and circRNA-protein networks were constructed using Cytoscape. The relationship between targeted genes and immune infiltration was identified using the GEPIA2 and TIMER2 online server tools.

RESULTS

A ceRNA network, including eight circRNAs, five miRNAs, and six mRNAs, was revealed. Moreover, a circRNA-protein network, including eight circRNAs and 49 proteins, was established. The targeted genes, ENOX1, NCAM1, SAMD4A, and ZC3H10, are closely related to CRC tumour-infiltrating macrophages.

CONCLUSIONS

We analysed the characteristics of circRNA from RPPH1 as competing for endogenous RNA binding miRNA or protein in CRC macrophage infiltration. The results point towards the development of a new diagnostic and therapeutic paradigm for CRC.

Preclinical Identification of Sulfasalazine’s Therapeutic Potential for Suppressing Colorectal Cancer Stemness and Metastasis through Targeting KRAS/MMP7/CD44 Signaling

Approximately 25% of colorectal cancer (CRC) patients will develop metastatic (m)CRC despite treatment interventions. In this setting, tumor cells are attracted to the epidermal growth factor receptor (EGFR) oncogene. Kirsten rat sarcoma (RAS) 2 viral oncogene homolog (KRAS) mutations were reported to drive CRC by promoting cancer progression in activating Wnt/β-catenin and RAS/extracellular signal-regulated kinase (ERK) pathways. In addition, KRAS is associated with almost 40% of patients who acquire resistance to EGFR inhibitors in mCRC. Multiple studies have demonstrated that cancer stem cells (CSCs) promote tumorigenesis, tumor growth, and resistance to therapy. One of the most common CSC prognostic markers widely reported in CRC is a cluster of differentiation 44 (CD44), which regulates matrix metalloproteinases 7/9 (MMP7/9) to promote tumor progression and metastasis; however, the molecular role of CD44 in CRC is still unclear. In invasive CRC, overexpression of MMP7 was reported in tumor cells compared to normal cells and plays a crucial function in CRC cetuximab and oxaliplatin resistance and distant metastasis. Here, we utilized a bioinformatics analysis and identified overexpression of KRAS/MMP7/CD44 oncogenic signatures in CRC tumor tissues compared to normal tissues. In addition, a high incidence of mutations in KRAS and CD44 were associated with some of the top tumorigenic oncogene’s overexpression, which ultimately promoted a poor response to chemotherapy and resistance to some FDA-approved drugs. Based on these findings, we explored a computational approach to drug repurposing of the drug, sulfasalazine, and our in silico molecular docking revealed unique interactions of sulfasalazine with the KRAS/MMP7/CD44 oncogenes, resulting in high binding affinities compared to those of standard inhibitors. Our in vitro analysis demonstrated that sulfasalazine combined with cisplatin reduced cell viability, colony, and sphere formation in CRC cell lines. In addition, sulfasalazine alone and combined with cisplatin suppressed the expression of KRAS/MMP7/CD44 in DLD-1 and HCT116 cell lines. Thus, sulfasalazine is worthy of further investigation as an adjuvant agent for improving chemotherapeutic responses in CRC patients.

COVID-19: Immunohistochemical Analysis of TGF-β Signaling Pathways in Pulmonary Fibrosis

Acute respiratory distress syndrome (ARDS) followed by repair with lung remodeling is observed in COVID-19. These findings can lead to pulmonary terminal fibrosis, a form of irreversible sequelae. There is evidence that TGF-β is intimately involved in the fibrogenic process. When activated, TGF-β promotes the differentiation of fibroblasts into myofibroblasts and regulates the remodeling of the extracellular matrix (ECM). In this sense, the present study evaluated the histopathological features and immunohistochemical biomarkers (ACE-2, AKT-1, Caveolin-1, CD44v6, IL-4, MMP-9, α-SMA, Sphingosine-1, and TGF-β1 tissue expression) involved in the TGF-β1 signaling pathways and pulmonary fibrosis. The study consisted of 24 paraffin lung samples from patients who died of COVID-19 (COVID-19 group), compared to 10 lung samples from patients who died of H1N1pdm09 (H1N1 group) and 11 lung samples from patients who died of different causes, with no lung injury (CONTROL group). In addition to the presence of alveolar septal fibrosis, diffuse alveolar damage (DAD) was found to be significantly increased in the COVID-19 group, associated with a higher density of Collagen I (mature) and III (immature). There was also a significant increase observed in the immunoexpression of tissue biomarkers ACE-2, AKT-1, CD44v6, IL-4, MMP-9, α-SMA, Sphingosine-1, and TGF-β1 in the COVID-19 group. A significantly lower expression of Caveolin-1 was also found in this group. The results suggest the participation of TGF-β pathways in the development process of pulmonary fibrosis. Thus, it would be plausible to consider therapy with TGF-β inhibitors in those patients recovered from COVID-19 to mitigate a possible development of pulmonary fibrosis and its consequences for post-COVID-19 life quality.

CD44: A Multifunctional Mediator of Cancer Progression

CD44, a non-kinase cell surface transmembrane glycoprotein, has been widely implicated as a cancer stem cell (CSC) marker in several cancers. Cells overexpressing CD44 possess several CSC traits, such as self-renewal and epithelial-mesenchymal transition (EMT) capability, as well as a resistance to chemo- and radiotherapy. The CD44 gene regularly undergoes alternative splicing, resulting in the standard (CD44s) and variant (CD44v) isoforms. The interaction of such isoforms with ligands, particularly hyaluronic acid (HA), osteopontin (OPN) and matrix metalloproteinases (MMPs), drive numerous cancer-associated signalling. However, there are contradictory results regarding whether high or low CD44 expression is associated with worsening clinicopathological features, such as a higher tumour histological grade, advanced tumour stage and poorer survival rates. Nonetheless, high CD44 expression significantly contributes to enhanced tumourigenic mechanisms, such as cell proliferation, metastasis, invasion, migration and stemness; hence, CD44 is an important clinical target. This review summarises current research regarding the different CD44 isoform structures and their roles and functions in supporting tumourigenesis and discusses CD44 expression regulation, CD44-signalling pathways and interactions involved in cancer development. The clinical significance and prognostic value of CD44 and the potential of CD44 as a therapeutic target in cancer are also addressed.

Liquid Biopsy-Based Colorectal Cancer Screening via Surface Markers of Circulating Tumor Cells

Colorectal cancer (CRC) is ranked second for cancer-related deaths worldwide with approximately half of the patients being diagnosed at the late stages. The untimely detection of CRC results in advancement to the metastatic stage and nearly 90% of cancer-related deaths. The early detection of CRC is crucial to decrease its overall incidence and mortality rates. The recent introduction of circulating tumor cells (CTCs) has enabled a less invasive sampling method from liquid biopsies, besides revealing key information toward CRC metastasis. The current gold standard for CTC identification is the CellSearch® system (Veridex). This first-generation instrumentation relies on a single cell surface marker (CSM) to capture and count CTCs. Detection of CTCs allows the identification of patients at risk for metastasis, whereas CTC enumeration could improve risk assessment, monitoring of systemic therapy, and detection of therapy resistance in advanced metastatic CRC. In this review, we compared the pros and cons between single CSM-based CTC enrichment techniques and multi-marker-based systems. We also highlighted the challenges faced in the routine implementation of CSM-dependent CTC detection methods in CRC screening, prediction, prognosis, disease monitoring, and therapy selection toward precision medicine, as well as the dwelling on post-CTC analysis and characterization methods.

Hyaluronan Functions in Wound Repair That Are Captured to Fuel Breast Cancer Progression

Signaling from an actively remodeling extracellular matrix (ECM) has emerged as a critical factor in regulating both the repair of tissue injuries and the progression of diseases such as metastatic cancer. Hyaluronan (HA) is a major component of the ECM that normally functions in tissue injury to sequentially promote then suppress inflammation and fibrosis, a duality in which is featured, and regulated in, wound repair. These essential response-to-injury functions of HA in the microenvironment are hijacked by tumor cells for invasion and avoidance of immune detection. In this review, we first discuss the numerous size-dependent functions of HA and emphasize the multifunctional nature of two of its receptors (CD44 and RHAMM) in regulating the signaling duality of HA in excisional wound healing. This is followed by a discussion of how HA metabolism is de-regulated in malignant progression and how targeting HA might be used to better manage breast cancer progression.

Re-Expression of Poly/Oligo-Sialylated Adhesion Molecules on the Surface of Tumor Cells Disrupts Their Interaction with Immune-Effector Cells and Contributes to Pathophysiological Immune Escape

Glycans linked to surface proteins are the most complex biological macromolecules that play an active role in various cellular mechanisms. This diversity is the basis of cell-cell interaction and communication, cell growth, cell migration, as well as co-stimulatory or inhibitory signaling. Our review describes the importance of neuraminic acid and its derivatives as recognition elements, which are located at the outermost positions of carbohydrate chains linked to specific glycoproteins or glycolipids. Tumor cells, especially from solid tumors, mask themselves by re-expression of hypersialylated neural cell adhesion molecule (NCAM), neuropilin-2 (NRP-2), or synaptic cell adhesion molecule 1 (SynCAM 1) in order to protect themselves against the cytotoxic attack of the also highly sialylated immune effector cells. More particularly, we focus on α-2,8-linked polysialic acid chains, which characterize carrier glycoproteins such as NCAM, NRP-2, or SynCam-1. This characteristic property correlates with an aggressive clinical phenotype and endows them with multiple roles in biological processes that underlie all steps of cancer progression, including regulation of cell-cell and/or cell-extracellular matrix interactions, as well as increased proliferation, migration, reduced apoptosis rate of tumor cells, angiogenesis, and metastasis. Specifically, re-expression of poly/oligo-sialylated adhesion molecules on the surface of tumor cells disrupts their interaction with immune-effector cells and contributes to pathophysiological immune escape. Further, sialylated glycoproteins induce immunoregulatory cytokines and growth factors through interactions with sialic acid-binding immunoglobulin-like lectins. We describe the processes, which modulate the interaction between sialylated carrier glycoproteins and their ligands, and illustrate that sialic acids could be targets of novel therapeutic strategies for treatment of cancer and immune diseases.

CD44v6 Defines a New Population of Circulating Tumor Cells Not Expressing EpCAM

Simple Summary

In the present work, we describe (for the first time) the use of the transmembrane protein, CD44v6, to detect CTCs from blood samples of several patients with colorectal or breast cancer. We used CD44v6 antibodies to demonstrate that live CTCs can be specifically purified from CRC patient blood samples via magnetic bead- or FACS-based isolation techniques. Finally, we demonstrated that CD44v6-positive CTCs rarely expressed EpCam, which is currently the gold standard to enumerate CTCs, suggesting the need to use a combination of markers for a more comprehensive view of CTC heterogeneity.

Abstract

Circulating tumor cells (CTCs) are promising diagnostic and prognostic tools for clinical use. In several cancers, including colorectal and breast, the CTC load has been associated with a therapeutic response as well as progression-free and overall survival. However, counting and isolating CTCs remains sub-optimal because they are currently largely identified by epithelial markers such as EpCAM. New, complementary CTC surface markers are therefore urgently needed. We previously demonstrated that a splice variant of CD44, CD44 variable alternative exon 6 (CD44v6), is highly and specifically expressed by CTC cell lines derived from blood samples in colorectal cancer (CRC) patients. Two different approaches—immune detection coupled with magnetic beads and fluorescence-activated cell sorting—were optimized to purify CTCs from patient blood samples based on high expressions of CD44v6. We revealed the potential of the CD44v6 as a complementary marker to EpCAM to detect and purify CTCs in colorectal cancer blood samples. Furthermore, this marker is not restricted to colorectal cancer since CD44v6 is also expressed on CTCs from breast cancer patients. Overall, these results strongly suggest that CD44v6 could be useful to enumerate and purify CTCs from cancers of different origins, paving the way to more efficacious combined markers that encompass CTC heterogeneity.

Beyond Colonoscopy: Exploring New Cell Surface Biomarkers for Detection of Early, Heterogenous Colorectal Lesions

Colorectal cancer (CRC) is the third leading cause of cancer-related deaths among both men and women in the United States. Early detection and surgical removal of high-risk lesions in the colon can prevent disease from developing and spreading. Despite implementation of programs aimed at early detection, screening colonoscopies fail to detect a fraction of potentially aggressive colorectal lesions because of their location or nonobvious morphology. Optical colonoscopies, while highly effective, rely on direct visualization to detect changes on the surface mucosa that are consistent with dysplasia. Recent advances in endoscopy techniques and molecular imaging permit microscale visualization of the colonic mucosa. These technologies can be combined with various molecular probes that recognize and target heterogenous lesion surfaces to achieve early, real-time, and potentially non-invasive, detection of pre-cancerous lesions. The primary goal of this review is to contextualize existing and emergent CRC surface biomarkers and assess each’s potential as a candidate marker for early marker-based detection of CRC lesions. CRC markers that we include were stratified by the level of support gleaned from peer-reviewed publications, abstracts, and databases of both CRC and other cancers. The selected biomarkers, accessible on the cell surface and preferably on the luminal surface of the colon tissue, are organized into three categories: (1) established biomarkers (those with considerable data and high confidence), (2) emerging biomarkers (those with increasing research interest but with less supporting data), and (3) novel candidates (those with very recent data, and/or supportive evidence from other tissue systems). We also present an overview of recent advances in imaging techniques useful for visual detection of surface biomarkers, and discuss the ease with which these methods can be combined with microscopic visualization.

The correlation of epithelial-mesenchymal transition-related gene expression and the clinicopathologic features of colorectal cancer patients in Taiwan

Colorectal cancer (CRC) is the third most commonly diagnosed malignancy and the second leading cause of cancer-related deaths in the world. It has been the most prevalent malignancy in Taiwan for consecutive thirteen years. Despite the diversity of its etiologic and pathophysiologic factors, a biological process named as epithelial-mesenchymal transition (EMT) is indispensable in the progression of epithelial cancer. Our aim is to investigate the correlation between the expression of 8 EMT-related proteins (E-cadherin, β-catenin, claudin-1, CD44, N-cadherin, fibronectin, vimentin, S100A4) and the clinicopathologic features of CRC in Taiwan, along with the DNA CpG epigenetic status of CD44 gene. In immunohistochemical assessment, decreased expression of E-cadherin is statistically associated with the progression of cancer stage, while decreased expression of claudin-1 as well as increased β-catenin nuclear translocation and N-cadherin expression is statistically associated with the progression of histopathologic grade. E-cadherin, nuclear β-catenin and claudin-1 are also associated with other important prognostic factors, including nodal metastasis, tumor deposits, and elevated serum CA 19-9 levels. In addition, the left-sided colon and rectal cancers show increased nuclear translocation of β-catenin compared to the right-sided colon cancers, while the rectal cancers show increased fibronectin expression compared to the right-sided and left-sided colon cancers. Moreover, vimentin is aberrantly expressed in one case of signet-ring cell carcinoma. The DNA methylation levels of CD44 gene promoter between the tumoral and non-tumorous tissues by NGS comparison showed statistical difference on six CpG sites. However, such difference may not be sufficient because these DNA methylation proportions are too low to inactivate CD44 gene. Our results demonstrate the expression of E-cadherin, claudin-1, and nuclear β-catenin is closely related to the clinicopathologic prognostic determinants of CRC in Taiwan. The DNA methylation level of CD44 gene and its protein expression, however, show no correlation with the clinicopathologic features in CRC.

The Interaction between Reactive Peritoneal Mesothelial Cells and Tumor Cells via Extracellular Vesicles Facilitates Colorectal Cancer Dissemination

Advanced colorectal cancer (CRC) is highly metastatic and often results in peritoneal dissemination. The extracellular vesicles (EVs) released by cancer cells in the microenvironment are important mediators of tumor metastasis. We investigated the contribution of EV-mediated interaction between peritoneal mesothelial cells (MCs) and CRC cells in generating a pro-metastatic environment in the peritoneal cavity. Peritoneal MCs isolated from peritoneal lavage fluids displayed high CD44 expression, substantial mesothelial-to-mesenchymal transition (MMT) and released EVs that both directed tumor invasion and caused reprogramming of secretory profiles by increasing TGF-β1 and uPA/uPAR expression and MMP-2/9 activation in tumor cells. Notably, the EVs released by tumor cells induced apoptosis by activating caspase-3, peritoneal MC senescence, and MMT, thereby augmenting the tumor-promoting potential of these cells in the peritoneal cavity. By using pantoprazole, we reduced the biogenesis of EVs and their pro-tumor functions. In conclusion, our findings provided evidence of underlying mechanisms of CRC dissemination driven by the interaction of peritoneal MCs and tumor cells via the EVs released in the peritoneal cavity, which may have important implications for the clinical management of patients.

A novel tumor suppressor role of myosin light chain kinase splice variants through downregulation of the TEAD4/CD44 axis

Myosin light chain kinase (MLCK) regulates actinomyosin contraction. Two splice variants of long MLCK are expressed in epithelial cells and divergently regulate gut barrier functions; reduced MLCK levels in human colorectal cancers (CRC) with unclarified significance have been reported. CRC are solid tumors clonally sustained by stem cells highly expressing CD44 and CD133. The aim was to investigate the role of MLCK splice variants in CRC tumorigenesis. We found lower MLCK1/2 and higher CD44 expression in human CRC, but no change in CD133 or LGR5. Large-scale bioinformatics showed an inverse relationship between MYLK and CD44 in human sample gene datasets. A 3-fold increased tumor burden was observed in MLCK(-/-) mice compared with wild-type (WT) mice in a chemical-induced CRC model. Primary tumorspheres derived from the MLCK(-/-) mice displayed larger sizes and higher CD44 transcript levels than those from the WT mice. Bioinformatics revealed binding of TEAD4 (a transcriptional enhancer factor family member in the Hippo pathway) to CD44 promoter, which was confirmed by luciferase reporter assay. Individually expressing MLCK1 and MLCK2 variants in the MLCK-knockout (KO) Caco-2 cells inhibited the nuclear localization of TEAD4 cofactors, VGLL3 and YAP1, respectively, and both variants reduced the CD44 transcription. Accelerated cell cycle transit was observed in the MLCK-KO cells, whereby expression of MLCK1/2 variants counterbalanced the cell hyperproliferation. In conclusion, MLCK1/2 variants are novel tumor suppressors by downregulating the TEAD4/CD44 axis via reducing nuclear translocation of distinct transcriptional coactivators. The reduction of epithelial MLCKs, especially isoform 2, may drive cancer stemness and tumorigenesis.

Altered Expression of MBNL Family of Alternative Splicing Factors in Colorectal Cancer

BACKGROUND/AIM

Colorectal cancer is currently the third leading cause of cancer-related deaths and recently, alternative splicing has risen as its important regulator and potential treatment target. In the present study, we analyzed gene expression of the MBNL family of regulators of alternative splicing in various stages of colorectal cancer development, together with the MBNL-target splicing events in FOXP1 and EPB41L3 genes and tumor-related CD44 variants.

MATERIALS AND METHODS

Samples of tumor tissue and non-malignant mucosa from 108 patients were collected. After RNA isolation and reverse transcription, the relative gene expression of a selected gene panel was tested by quantitative real-time PCR, followed by statistical analysis.

RESULTS

MBNL expression was decreased in tumor tissue compared to non-tumor mucosa. In addition, lower expression was observed for the variants of FOXP1 and EPB41L3, while higher expression in tumor tissue was detected both for total CD44 and its cancer-related variants 3 and 6. Transcript levels of the MBNL genes were not found to be related to any of the studied clinicopathological characteristics. Multiple significant associations were identified in the target gene panel, including higher transcript levels of FOXP1 and CD44v3 in patients with distant metastases and connections between recurrence-free survival and altered levels of FOXP1 and CD44v3.

CONCLUSION

Our results identified for the first-time deregulation of MBNL genes in colorectal cancer. Down-regulation of their transcripts in tumor tissue compared to matched non-tumor mucosa can lead to transition of alternative splicing patterns towards a less differentiated phenotype, which highlights the importance of alternative splicing regulation for tumor growth and propagation.

Molecular features and gene expression signature of metastatic colorectal cancer (Review)

Uncontrollable metastatic outgrowth process is the leading cause of mortality worldwide, even in the case of colorectal cancer. Colorectal cancer (CRC) accounts for approximately 10% of all annually diagnosed cancers and 50% of CRC patients will develop metastases in the course of disease. Most patients with metastatic CRC have incurable disease. Even if patients undergo resection of liver metastases, the 5‑year survival rate ranges from 25 to 58%. Next‑generation sequencing of tumour specimens from large colorectal cancer patient cohorts has led to major advances in elucidating the genomic landscape of these tumours and paired metastases. The expression profiles of primary CRC and their metastatic lesions at both the gene and pathway levels were compared and led to the selection of early driver genes responsible for carcinogenesis and metastasis‑specific genes that increased the metastatic process. The genetic, transcriptional and epigenetic alteration encoded by these genes and their combination influence many pivotal signalling pathways, enabling the dissemination and outgrowth in distant organs. Therapeutic regimens affecting several different active pathways may have important implications for therapeutic efficacy.

The Role of Cancer Stem Cells in Colorectal Cancer: From the Basics to Novel Clinical Trials

The treatment options available for colorectal cancer (CRC) have increased over the years and have significantly improved the overall survival of CRC patients. However, the response rate for CRC patients with metastatic disease remains low and decreases with subsequent lines of therapy. The clinical management of patients with metastatic CRC (mCRC) presents a unique challenge in balancing the benefits and harms while considering disease progression, treatment-related toxicities, drug resistance and the patient's overall quality of life. Despite the initial success of therapy, the development of drug resistance can lead to therapy failure and relapse in cancer patients, which can be attributed to the cancer stem cells (CSCs). Thus, colorectal CSCs (CCSCs) contribute to therapy resistance but also to tumor initiation and metastasis development, making them attractive potential targets for the treatment of CRC. This review presents the available CCSC isolation methods, the clinical relevance of these CCSCs, the mechanisms of drug resistance associated with CCSCs and the ongoing clinical trials targeting these CCSCs. Novel therapeutic strategies are needed to effectively eradicate both tumor growth and metastasis, while taking into account the tumor microenvironment (TME) which plays a key role in tumor cell plasticity.

Cancer-associated fibroblasts secrete hypoxia-induced serglycin to promote head and neck squamous cell carcinoma tumor cell growth in vitro and in vivo by activating the Wnt/β-catenin pathway

BACKGROUND

The tumor microenvironment (TME) is known to play a prominent role in the pathology of head and neck squamous cell carcinoma (HNSCC). Cancer-associated fibroblasts (CAFs) have been reported to regulate tumor progression, and serglycin (SRGN), one of the paracrine cytokines of CAFs, has been reported to play an important role in various signaling pathways. Hypoxia is a distinct feature of the HNSCC TME. Here, we investigated the mechanism underlying CAF-secreted SRGN leading to HNSCC progression under hypoxia.

METHODS

Immunohistochemical staining was used to detect SRGN expression in clinical HNSCC samples, after which its relation with patient survival was assessed. CAFs were isolated and SRGN expression and secretion by CAFs under normoxia and hypoxia were confirmed using qRT-PCR and ELISA assays, respectively. HNSCC sphere-forming abilities, stemness-related gene expression, and chemoresistance were assessed with or without SRGN treatment. A Wnt/β-catenin pathway inhibitor (PNU-75,654) was used to block its activation, after which nuclear translocation of β-catenin in the presence of SRGN with or without PNU-75,654 was evaluated. shRNAs were used to stably knock down SRGN expression in CAFs. HNSCC tumor cells with or without (SRGN silenced) CAFs were inoculated submucosally in nude mice after which tumor weights and sizes were determined to assess the effects of CAFs and SRGN on tumor growth.

RESULTS

We found that SRGN was expressed in both HNSCC tumor and stroma cells, and that high SRGN expression in the stroma cells, but not in the tumor cells, was significantly related to a poor patient survival. After the extraction of CAFs and normal fibroblasts (NFs) from paired tumor samples and adjacent normal tissues, respectively, we found that the expression of CAF-specific genes, including fibroblast activation protein (FAP) and alpha-smooth muscle actin (α-SMA), was clearly upregulated compared to the expression in NFs. The hypoxia marker HIF-1α was found to be expressed in tumor stroma cells. Hypoxyprobe immunofluorescence staining confirmed stromal hypoxia in an orthotopic tongue cancer mouse model. Using qRT-PCR and ELISA we found that a hypoxic TME upregulated SRGN expression and secretion by CAFs. SRGN markedly enhanced the sphere-forming ability, stemness-related gene expression and chemoresistance of HNSCC tumor cells. SRGN activated the Wnt/β-catenin pathway and promoted β-catenin nuclear translocation. An in vivo study confirmed that CAFs can accelerate HNSCC tumor growth, and that this effect can be counteracted by SRGN silencing.

CONCLUSIONS

Our data indicate that a hypoxic tumor stroma can lead to upregulation of SRGN expression. SRGN secreted by CAFs can promote β-catenin nuclear translocation to activate downstream signaling pathways, leading to enhanced HNSCC cell stemness, chemoresistance and accelerated tumor growth.

CD44 and Tumor-Derived Extracellular Vesicles (TEVs). Possible Gateway to Cancer Metastasis

Cancer metastasis, the final stage of tumor progression, is a complex process governed by the interplay of multiple types of cells and the tumor microenvironment. One of the aspects of this interplay involves the release of various factors by the tumor cells alone or by forcing other cells to do so. As a consequence of these actions, tumor cells are prepared in favorable conditions for their dissemination and spread to other sites/organs, which guarantees their escape from immunosurveillance and further progression. Tumor-derived extracellular vesicles (TEVs) represent a heterogeneous population of membrane-bound vesicles that are being actively released by different tumors. The array of proteins (i.e., receptors, cytokines, chemokines, etc.) and nucleic acids (i.e., mRNA, miR, etc.) that TEVs can transfer to other cells is often considered beneficial for the tumor’s survival and proliferation. One of the proteins that is associated with many different tumors as well as their TEVs is a cluster of differentiation 44 in its standard (CD44s) and variant (CD44v) form. This review covers the present information regarding the TEVs-mediated CD44s/CD44v transfer/interaction in the context of cancer metastasis. The content and the impact of the transferred cargo by this type of TEVs also are discussed with regards to tumor cell dissemination.

ILC1 drive intestinal epithelial and matrix remodelling

Organoids can shed light on the dynamic interplay between complex tissues and rare cell types within a controlled microenvironment. Here, we develop gut organoid cocultures with type-1 innate lymphoid cells (ILC1) to dissect the impact of their accumulation in inflamed intestines. We demonstrate that murine and human ILC1 secrete transforming growth factor β1, driving expansion of CD44v6+ epithelial crypts. ILC1 additionally express MMP9 and drive gene signatures indicative of extracellular matrix remodelling. We therefore encapsulated human epithelial-mesenchymal intestinal organoids in MMP-sensitive, synthetic hydrogels designed to form efficient networks at low polymer concentrations. Harnessing this defined system, we demonstrate that ILC1 drive matrix softening and stiffening, which we suggest occurs through balanced matrix degradation and deposition. Our platform enabled us to elucidate previously undescribed interactions between ILC1 and their microenvironment, which suggest that they may exacerbate fibrosis and tumour growth when enriched in inflamed patient tissues.

Polymeric micelles targeted against CD44v6 receptor increase niclosamide efficacy against colorectal cancer stem cells and reduce circulating tumor cells in vivo

Colorectal cancer (CRC) is a highly prevalent disease worldwide. Patient survival is hampered by tumor relapse and the appearance of drug-resistant metastases, which are sustained by the presence of cancer stem cells (CSC). Specific delivery of anti-CSC chemotherapeutic drugs to tumors by using targeted drug delivery systems that can also target CSC sub-population might substantially improve current clinical outcomes. CD44v6 is a robust biomarker for advanced CRC and CSC, due to its functional role in tumorigenesis and cancer initiation process. Here, we show that CD44v6-targeted polymeric micelles (PM) loaded with niclosamide (NCS), a drug against CSC, is a good therapeutic strategy against colorectal CSC and circulating tumor cells (CTC) in vivo. HCT116 cells were sorted according to their CD44v6 receptor expression into CD44v6+ (high) and CDv44v6- (low) subpopulations. Accordingly, CD44v6+ cells presented stemness properties, such as overexpression of defined stemness markers (ALDH1A1, CD44v3 and CXCR4) and high capacity to form colonspheres in low attachment conditions. NCS-loaded PM functionalized with an antibody fragment against CD44v6 (Fab-CD44v6) presented adequate size, charge, and encapsulation efficiency. In addition, Fab-CD44v6 significantly increased PM internalization in CD44v6+ cells. Further, encapsulation of NCS improved its effectiveness in vitro, particularly against colonspheres, and allowed to increase its intravenous dosage in vivo by increasing the amount of NCS able to be administered without causing toxicity. Remarkably, functionalized PM accumulate in tumors and significantly reduce CTC in vivo. In conclusion, CD44v6 targeted PM meet the essential conditions to become an efficient anti-CSC therapy.

Radiochemistry, Production Processes, Labeling Methods, and ImmunoPET Imaging Pharmaceuticals of Iodine-124

Target-specific biomolecules, monoclonal antibodies (mAb), proteins, and protein fragments are known to have high specificity and affinity for receptors associated with tumors and other pathological conditions. However, the large biomolecules have relatively intermediate to long circulation half-lives (>day) and tumor localization times. Combining superior target specificity of mAbs and high sensitivity and resolution of the PET (Positron Emission Tomography) imaging technique has created a paradigm-shifting imaging modality, ImmunoPET. In addition to metallic PET radionuclides, 124I is an attractive radionuclide for radiolabeling of mAbs as potential immunoPET imaging pharmaceuticals due to its physical properties (decay characteristics and half-life), easy and routine production by cyclotrons, and well-established methodologies for radioiodination. The objective of this report is to provide a comprehensive review of the physical properties of iodine and iodine radionuclides, production processes of 124I, various 124I-labeling methodologies for large biomolecules, mAbs, and the development of 124I-labeled immunoPET imaging pharmaceuticals for various cancer targets in preclinical and clinical environments. A summary of several production processes, including 123Te(d,n)124I, 124Te(d,2n)124I, 121Sb(α,n)124I, 123Sb(α,3n)124I, 123Sb(3He,2n)124I, natSb(α, xn)124I, natSb(3He,n)124I reactions, a detailed overview of the 124Te(p,n)124I reaction (including target selection, preparation, processing, and recovery of 124I), and a fully automated process that can be scaled up for GMP (Good Manufacturing Practices) production of large quantities of 124I is provided. Direct, using inorganic and organic oxidizing agents and enzyme catalysis, and indirect, using prosthetic groups, 124I-labeling techniques have been discussed. Significant research has been conducted, in more than the last two decades, in the development of 124I-labeled immunoPET imaging pharmaceuticals for target-specific cancer detection. Details of preclinical and clinical evaluations of the potential 124I-labeled immunoPET imaging pharmaceuticals are described here.