ALCAM/CD166 is a TGF-β-responsive marker and functional regulator of prostate cancer metastasis to bone

Epithelial-to-mesenchymal transition (EMT) and cancer metastasis: the status quo of methods and experimental models 2025

Epithelial-to-mesenchymal transition (EMT) is a crucial cellular process for embryogenesis, wound healing, and cancer progression. It involves a shift in cell interactions, leading to the detachment of epithelial cells and activation of gene programs promoting a mesenchymal state. EMT plays a significant role in cancer metastasis triggering tumor initiation and stemness, and activates metastatic cascades resulting in resistance to therapy. Moreover, reversal of EMT contributes to the formation of metastatic lesions. Metastasis still needs to be better understood functionally in its major but complex steps of migration, invasion, intravasation, dissemination, which contributes to the establishment of minimal residual disease (MRD), extravasation, and successful seeding and growth of metastatic lesions at microenvironmentally heterogeneous sites. Therefore, the current review article intends to present, and discuss comprehensively, the status quo of experimental models able to investigate EMT and metastasis in vitro and in vivo, for researchers planning to enter the field. We emphasize various methods to understand EMT function and the major steps of metastasis, including diverse migration, invasion and matrix degradation assays, microfluidics, 3D co-culture models, spheroids, organoids, or latest spatial and imaging methods to analyze complex compartments. In vivo models such as the chorionallantoic membrane (CAM) assay, cell line-derived and patient-derived xenografts, syngeneic, genetically modified, and humanized mice, are presented as a promising arsenal of tools to analyze intravasation, site specific metastasis, and treatment response. Furthermore, we give a brief overview on methods detecting dissemination and MRD in carcinomas, highlighting its significance in tracking the course of disease and response to treatment. Enhanced lineage tracking tools, dynamic in vivo imaging, and therapeutically useful in vivo models as powerful preclinical tools may still better reveal functional interdependencies between metastasis and EMT. Future directions are discussed in light of emerging views on the biology, diagnosis, and treatment of EMT and metastasis.

SCGB3A1-Epi and KLK10-Epi Crosstalk With Fibroblasts Promotes Liver Metastasis of Breast Cancer and Pancreatic Ductal Adenocarcinoma

BACKGROUND

The liver often serves as the principal site for metastatic spread from a variety of solid tumors, and metastasis to the liver markedly diminishes patient survival. Single-cell RNA sequencing (scRNA-seq) has helped uncover the complexity of liver tumor metastasis. However, the key cellular subtypes of breast cancer and pancreatic ductal adenocarcinoma (PDAC) with liver metastasis and their mechanisms of action are unclear, making treatment difficult.

METHODS

We used integrated scRNA-seq data to dissect liver metastasis-specific epithelial cell subtypes in breast cancer and PDAC, and elucidated their mechanisms through functional analyses and intercellular interactions with fibroblasts.

RESULTS

Interestingly, our results show that SCGB3A1-Epi and KLK10-Epi are key drivers of liver metastasis in breast cancer and PDAC, respectively. These subtypes are associated with high malignancy rates and involved in oxidative phosphorylation and other critical pathways. Specific ligand-receptor interactions were observed between these epithelial subtypes and fibroblasts, with significant interactions between CD74-APP receptors in SCGB3A1-Epi and Fib-11 in breast cancer and between SPP1-CD44 receptors in KLK10-Epi and Fib-11 in PDAC. High expression levels of Fib-11 and CD74 were correlated with improved survival in breast cancer, whereas high SPP1 and CD44 expression predicted worse PDAC outcomes. Fib-11 is implicated in signaling pathways associated with tumor metastasis, particularly those involving cell adhesion molecules.

CONCLUSIONS

We revealed the cellular heterogeneity of liver metastasis and provided a crucial research foundation for developing novel therapeutic strategies to specifically target metastatic cell subtypes, thereby enhancing patient prognosis.

Patient-Derived Colorectal Cancer Extracellular Matrices Modulate Cancer Cell Stemness Markers

Although it has been shown that the tumor extracellular matrix (ECM) may sustain the cancer stem cell (CSC) niche, its role in the modulation of CSC properties remains poorly characterized. To elucidate this, paired tumor and adjacent normal mucosa, derived from colon cancer patients' surgical resections, were decellularized and recellularized with two distinct colon cancer cells, HT-29 or HCT-15. Methods: The matrix impact on cancer stem cell marker expression was evaluated by flow cytometry and qRT-PCR, while transforming growth factor-β (TGF-β) secretion and matrix metalloprotease (MMP) activity were quantified by ELISA and zymography. Results: In contrast to their paired normal counterparts, the tumor decellularized matrices enhanced HT-29 expression of the pluripotency and stemness genes NANOG (p = 0.0117), SOX2 (p = 0.0156), and OCT4 (p = 0.0312) and of the epithelial-to-mesenchymal transition (EMT)-associated transcription factor SNAI1 (p = 0.0156). Notably, no significant differences were found in the expression of SLUG or TGFB on HT-29 or of the six transcripts on HCT-15 cells. HT-29 mRNA alterations were followed by enhanced expression of the stemness-associated receptors cluster of differentiation 44 (CD44), CD133, and CD166 (p = 0.0078), the secretion of TGF-β (p = 0.0286), and MMP-2 (p = 0.0081) and MMP-9 (p = 0.0402) proteolysis. To infer the clinical relevance of these findings, we assessed cohort databases and evidenced that patients expressing higher levels of the four stemness-associated genes (NANOG/SOX2/OCT4/SNAI1) had worse overall survival. This study demonstrates that normal and tumor matrices harbor different stemness potential and suggest patient-derived decellularized matrices as an excellent three-dimensional (3D) model to unveil stemness signatures, appointing candidates for future therapeutic strategies.

TGF-β1-mediated intercellular signaling fuels cooperative cellular invasion

Intratumoral heterogeneity drives cancer progression and influences treatment outcomes. The mechanisms underlying how cellular subpopulations communicate and cooperate to impact progression remain largely unknown. Here, we use collective invasion as a model to deconstruct processes underlying non-small cell lung cancer subpopulation cooperation. We reveal that collectively invading packs consist of heterogeneously cycling and non-cycling subpopulations using distinct pathways. We demonstrate that the follower subpopulation secretes transforming growth factor beta one (TGF-β1) to stimulate divergent subpopulation responses-including proliferation, pack cohesion, and JAG1-dependent invasion-depending on cellular context. While isolated followers maintain proliferation in response to TGF-β1, isolated leaders enter a quiescence-like cellular state. In contrast, leaders within a heterogeneous population sustain proliferation to maintain subpopulation proportions. In vivo, both leader and follower subpopulations are necessary for macro-metastatic disease progression. Taken together, these findings highlight that intercellular communication preserves tumor cell heterogeneity and promotes collective behaviors such as invasion and tumor progression.

Cross-Talk between the TGF-β and Cell Adhesion Signaling Pathways in Cancer

Transforming growth factor-β (TGF-β) is strongly associated with the cell adhesion signaling pathway in cell differentiation, migration, etc. Mechanistically, TGF-β is secreted in an inactive form and localizes to the extracellular matrix (ECM) via the latent TGF-β binding protein (LTBP). However, it is the release of mature TGF-β that is essential for the activation of the TGF-β signaling pathway. This progress requires specific integrins (one of the main groups of cell adhesion molecules (CAMs)) to recognize and activate the dormant TGF-β. In addition, TGF-β regulates cell adhesion ability through modulating CAMs expression. The aberrant activation of the TGF-β signaling pathway, caused by abnormal expression of key regulatory molecules (such as Smad proteins, certain transcription factors, and non-coding RNAs), promotes tumor invasive and metastasis ability via epithelial-mesenchymal transition (EMT) during the late stages of tumorigenesis. In this paper, we summarize the crosstalk between TGF-β and cell adhesion signaling pathway in cancer and its underlying molecular mechanisms.

Clinical significance of CD166 and HER-2 in different types of gastric cancer

INTRODUCTION

Cluster of differentiation 166 (CD166), a cancer stem cell (CSC) marker, and human epidermal growth factor receptor 2 (HER-2) are expressed in a diversity of malignancies and is associated with tumor progression. Although studies regarding the importance of CSC markers and HER-2 in gastric cancer (GC) have rapidly developed, their clinicopathological, prognosis, and diagnosis value still remain unsatisfying in GC. Therefore, the present study aims to investigate the clinical, prognostic, and diagnostic significance of CD166 and HER-2 in different histological types of GC.

MATERIALS AND METHODS

Bioinformatic analysis was applied to determine the clinical importance of CD166 and HER-2 expression based on their tissue localization in primary GC tumors and the normal adjacent samples. The expression patterns, clinical significance, prognosis, and diagnosis value of CD166 and HER-2 proteins in tissue microarrays (TMAs) of 206 GC samples, including Signet Ring Cell (SRC) and intestinal types and also 28 adjacent normal tissues were evaluated using immunohistochemistry (IHC).

RESULTS

The results indicated that the expression of CD166 (membranous and cytoplasmic) and HER-2 were significantly up-regulated in tumor cells compared to adjacent normal tissues (P = 0.010, P < 0.001, and P = 0.011, respectively). A statistically significant association was detected between a high level of membranous expression of CD166 and lymphovascular invasion (P = 0.006); We also observed a statistically significant association between high cytoplasmic expression of CD166 protein and more invasion of the subserosa (P = 0.040) in the SRC type. In contrast, there was no correlation between the expression of HER-2 and clinicopathologic characteristics. Both CD166 and HER-2 showed reasonable accuracy and high specificity as diagnostic markers.

CONCLUSION

Our results confirmed that increased membranous and cytoplasmic expression of CD166 showed clinical significance in the SRC type and is associated with the progression of the disease and more aggressive tumor behaviors. These findings can be used to assist in designating subgroups of patients that require different follow-up strategies, and also, they might be utilized as the prognostic or diagnostic biomarkers in these types of GC for prospective clinical application.

Multifaceted TGF-β signaling, a master regulator: From bench-to-bedside, intricacies, and complexities

Physiological embryogenesis and adult tissue homeostasis are regulated by transforming growth factor-β (TGF-β), an evolutionarily conserved family of secreted polypeptide factors, acting in an autocrine and paracrine manner. The role of TGF-β in inflammation, fibrosis, and cancer is complex and sometimes even contradictory, exhibiting either inhibitory or promoting effects depending on the stage of the disease. Under pathological conditions, especially fibrosis and cancer, overexpressed TGF-β causes extracellular matrix deposition, epithelial-mesenchymal transition, cancer-associated fibroblast formation, and/or angiogenesis. In this review article, we have tried to dive deep into the mechanism of action of TGF-β in inflammation, fibrosis, and carcinogenesis. As TGF-β and its downstream signaling mechanism are implicated in fibrosis and carcinogenesis blocking this signaling mechanism appears to be a promising avenue. However, targeting TGF-β carries substantial risk as this pathway is implicated in multiple homeostatic processes and is also known to have tumor-suppressor functions. There is a need for careful dosing of TGF-β drugs for therapeutic use and patient selection.

sBioSITe enables sensitive identification of the cell surface proteome through direct enrichment of biotinylated peptides

BACKGROUND

Cell surface proteins perform critical functions related to immune response, signal transduction, cell-cell interactions, and cell migration. Expression of specific cell surface proteins can determine cell-type identity, and can be altered in diseases including infections, cancer and genetic disorders. Identification of the cell surface proteome remains a challenge despite several enrichment methods exploiting their biochemical and biophysical properties.

METHODS

Here, we report a novel method for enrichment of proteins localized to cell surface. We developed this new approach designated surface Biotinylation Site Identification Technology (sBioSITe) by adapting our previously published method for direct identification of biotinylated peptides. In this strategy, the primary amine groups of lysines on proteins on the surface of live cells are first labeled with biotin, and subsequently, biotinylated peptides are enriched by anti-biotin antibodies and analyzed by liquid chromatography-tandem mass spectrometry (LC-MS/MS).

RESULTS

By direct detection of biotinylated lysines from PC-3, a prostate cancer cell line, using sBioSITe, we identified 5851 peptides biotinylated on the cell surface that were derived from 1409 proteins. Of these proteins, 533 were previously shown or predicted to be localized to the cell surface or secreted extracellularly. Several of the identified cell surface markers have known associations with prostate cancer and metastasis including CD59, 4F2 cell-surface antigen heavy chain (SLC3A2) and adhesion G protein-coupled receptor E5 (CD97). Importantly, we identified several biotinylated peptides derived from plectin and nucleolin, both of which are not annotated in surface proteome databases but have been shown to have aberrant surface localization in certain cancers highlighting the utility of this method.

CONCLUSIONS

Detection of biotinylation sites on cell surface proteins using sBioSITe provides a reliable method for identifying cell surface proteins. This strategy complements existing methods for detection of cell surface expressed proteins especially in discovery-based proteomics approaches.

Exploration of diagnostic biomarkers, microenvironment characteristics, and ursolic acid's therapeutic effect for benign prostate hyperplasia

Benign prostatic hyperplasia (BPH) and early-stage prostate cancer (PC) have similar symptoms, making it challenging to differentially diagnose these two conditions. The study used Weighted Gene Co-Expression Network Analysis, as well as two machine learning strategies to identify BPH-specific biomarkers based on an integrated transcriptome data from 922 samples. Eight prognostic genes (ALCAM, COL6A2, CRISP2, FOXF2, IGF1, PTN, SCN7A, and UAP1) were identified to be BPH-specific biomarkers with high accuracy and specificity. Moreover, we constructed a seven-gene diagnostic classifier to distinguish BPH from PC. The infiltrations of plasmacytoid dendritic cells and neutrophil cells showed distinct differences between BPH and non-BPH groups. Additionally, ursolic acid can reverse transcriptional features associated with the occurrence and progression of BPH. Both in vivo and in vitro experiments have confirmed that it induces apoptosis of BPH cells and inhibits cell proliferation by promoting cell cycle S-phase arrest. The diagnostic biomarkers, microenvironment characteristics, and therapeutic effect of ursolic acid explored in this study offer new diagnostic and therapeutic strategies for BPH.

Tissue-specific cancer stem/progenitor cells: Therapeutic implications

Surgical resection, chemotherapy, and radiation are the standard therapeutic modalities for treating cancer. These approaches are intended to target the more mature and rapidly dividing cancer cells. However, they spare the relatively quiescent and intrinsically resistant cancer stem cells (CSCs) subpopulation residing within the tumor tissue. Thus, a temporary eradication is achieved and the tumor bulk tends to revert supported by CSCs' resistant features. Based on their unique expression profile, the identification, isolation, and selective targeting of CSCs hold great promise for challenging treatment failure and reducing the risk of cancer recurrence. Yet, targeting CSCs is limited mainly by the irrelevance of the utilized cancer models. A new era of targeted and personalized anti-cancer therapies has been developed with cancer patient-derived organoids (PDOs) as a tool for establishing pre-clinical tumor models. Herein, we discuss the updated and presently available tissue-specific CSC markers in five highly occurring solid tumors. Additionally, we highlight the advantage and relevance of the three-dimensional PDOs culture model as a platform for modeling cancer, evaluating the efficacy of CSC-based therapeutics, and predicting drug response in cancer patients.

Gene variation impact on prostate cancer progression: Lymphocyte modulator, activation, and cell adhesion gene variant contribution

BACKGROUND

The view of prostate cancer (PCa) progression as a result of the interaction of epithelial cancer cells with the host's immune system is supported by the presence of tumor infiltrating lymphocytes (TILs). TILs fate and interaction with the tumor microenvironment is mediated by accessory molecules such as CD5 and CD6, two signal-transducing coreceptors involved in fine-tuning of T cell responses. While the nature of the CD5 ligand is still controversial, CD6 binds CD166/ALCAM, a cell adhesion molecule involved in progression and dissemination of epithelial cancers, including PCa. The purpose of the present study was to determine the role of CD5, CD6, and CD166/ALCAM gene variants in PCa.

METHODS

Functionally relevant CD5 (rs2241002 and rs2229177), CD6 (rs17824933, rs11230563, and rs12360861) and CD166/ALCAM (rs6437585, rs579565, rs1044243, and rs35271455) single nucleotide polymorphisms (SNPs) were genotyped in germline DNA samples from 376 PCa patients. Their association with PCa prognostic factors, namely biochemical recurrence (BCR) and International Society of Urological Pathology (ISUP) grade was analyzed by generalized linear models and survival analyses.

RESULT

Proportional hazards regression showed that the minor CD6 rs12360861^AA and CD166/ALCAM rs579565^AA genotypes were associated with earlier BCR, with hazard ratios of 2.65 (95% CI: 1.39-5.05, p = 0.003) and 1.86, (95% CI: 1.02-3.39, p = 0.043), respectively. Individually, none of the analyzed SNPs was significantly associated with ISUP grade, but haplotype analyses revealed association of the CD5 rs2241002^C -rs2229177^T haplotype with ISUP grade ≥2, with odds ratio of 1.52 (95% CI: 1.05-2.21, p = 0.026).

CONCLUSION

The results show the impact on PCa aggressiveness and recurrence brought about by gene variants involved in modulation of lymphocyte activation (CD5, CD6) and immune-epithelial cell adhesion (CD166/ALCAM) in PCa aggressiveness and recurrence, thus supporting a role for host immune response in PCa pathophysiology.

Biological and Clinical Aspects of Metastatic Spinal Tumors

Simple Summary

Spine metastases are a common life-threatening complication of advanced-stage malignancies and often result in poor prognosis. Symptomatic spine metastases develop in the course of about 10% of malignant neoplasms. Therefore, it is essential for contemporary medicine to understand metastatic processes in order to find appropriate, targeted therapeutic options. Our literature review aimed to describe the up-to-date knowledge about the molecular pathways and biomarkers engaged in the spine’s metastatic processes. Moreover, we described current data regarding bone-targeted treatment, the emerging targeted therapies, radiotherapy, and immunotherapy used for the treatment of spine metastases. We hope that knowledge comprehensively presented in our review will contribute to the development of novel drugs targeting specific biomarkers and pathways. The more we learn about the molecular aspects of cancer metastasis, the easier it will be to look for treatment methods that will allow us to precisely kill tumor cells.

Abstract

Spine metastases are a common life-threatening complication of advanced-stage malignancies and often result in poor prognosis. Symptomatic spine metastases develop in the course of about 10% of malignant neoplasms. Therefore, it is essential for contemporary medicine to understand metastatic processes in order to find appropriate, targeted therapeutic options. Thanks to continuous research, there appears more and more detailed knowledge about cancer and metastasis, but these transformations are extremely complicated, e.g., due to the complexity of reactions, the variety of places where they occur, or the participation of both tumor cells and host cells in these transitions. The right target points in tumor metastasis mechanisms are still being researched; that will help us in the proper diagnosis as well as in finding the right treatment. In this literature review, we described the current knowledge about the molecular pathways and biomarkers engaged in metastatic processes involving the spine. We also presented a current bone-targeted treatment for spine metastases and the emerging therapies targeting the discussed molecular mechanisms.

Prostate Cancer Stem Cells: Clinical Aspects and Targeted Therapies

Despite decades of research and successful improvements in diagnosis and therapy, prostate cancer (PC) remains a major challenge. In recent years, it has become clear that PC stem cells (PCSCs) are the driving force in tumorigenesis, relapse, metastasis, and therapeutic resistance of PC. In this minireview, we discuss the impact of PCSCs in the clinical practice. Moreover, new therapeutic approaches to combat PCSCs are presented with the aim to achieve an improved outcome for patients with PC.

Proteome profiling of enzalutamide-resistant cell lines and serum analysis identified ALCAM as marker of resistance in castration-resistant prostate cancer

Enzalutamide (ENZA) is a frequently used therapy in metastatic castration‐resistant prostate cancer (mCRPC). Baseline or acquired resistance to ENZA have been observed, but the molecular mechanisms of resistance are poorly understood. We aimed to identify proteins involved in ENZA resistance and to find therapy‐predictive serum markers. We performed comparative proteome analyses on ENZA‐sensitive parental (LAPC4, DuCaP) and ‐resistant prostate cancer cell lines (LAPC4‐ENZA, DuCaP‐ENZA) using liquid chromatography tandem mass spectrometry (LC‐MS/MS). The top four most promising candidate markers were selected using bioinformatic approaches. Serum concentrations of selected markers (ALCAM, AGR2, NDRG1, IDH1) were measured in pretreatment samples of 72 ENZA‐treated mCRPC patients using ELISA. In addition, ALCAM serum levels were measured in 101 Abiraterone (ABI) and 100 Docetaxel (DOC)‐treated mCRPC patients' baseline samples. Results were correlated with clinical and follow‐up data. The functional role of ALCAM in ENZA resistance was assessed in vitro using siRNA. Our proteome analyses revealed 731 significantly differentially abundant proteins between ENZA‐sensitive and ‐resistant cells and our filtering methods identified four biomarker candidates. Serum analyses of these proteins revealed only ALCAM to be associated with poor patient survival. Furthermore, higher baseline ALCAM levels were associated with poor survival in ABI‐ but not in DOC‐treated patients. In LAPC4‐ENZA resistant cells, ALCAM silencing by siRNA knockdown resulted in significantly enhanced ENZA sensitivity. Our analyses revealed that ALCAM serum levels may help to identify ENZA‐ and ABI‐resistant patients and may thereby help to optimize future clinical decision‐making. Our functional analyses suggest the possible involvement of ALCAM in ENZA resistance.

Advancing Treatment of Bone Metastases through Novel Translational Approaches Targeting the Bone Microenvironment

Bone metastases represent a lethal condition that frequently occurs in solid tumors such as prostate, breast, lung, and renal cell carcinomas, and increase the risk of skeletal-related events (SREs) including pain, pathologic fractures, and spinal cord compression. This unique metastatic niche consists of a multicellular complex that cancer cells co-opt to engender bone remodeling, immune suppression, and stromal-mediated therapeutic resistance. This review comprehensively discusses clinical challenges of bone metastases, novel preclinical models of the bone and bone marrow microenviroment, and crucial signaling pathways active in bone homeostasis and metastatic niche. These studies establish the context to summarize the current state of investigational agents targeting BM, and approaches to improve BM-targeting therapies. Finally, we discuss opportunities to advance research in bone and bone marrow microenvironments by increasing complexity of humanized preclinical models and fostering interdisciplinary collaborations to translational research in this challenging metastatic niche.

ALCAM-EGFR interaction regulates myelomagenesis

Multiple myeloma, a plasma cell malignancy in the bone marrow, remains largely incurable with currently available therapeutics. In this study, we discovered that the activated leukocyte cell adhesion molecule (ALCAM) interacted with epidermal growth factor receptor (EGFR), and regulated myelomagenesis. ALCAM was a negative regulator of myeloma clonogenicity. ALCAM expression was positively correlated with patients' survival. ALCAM-knockdown myeloma cells displayed enhanced colony formation in the presence of bone marrow stromal cells (BMSCs). BMSCs supported myeloma colony formation by secreted epidermal growth factor (EGF), which bound with its receptor (EGFR) on myeloma cells and activated Mek/Erk cell signaling, PI3K/Akt cell signaling, and hedgehog pathway. ALCAM could also bind with EGFR, block EGF from binding to EGFR, and abolish EGFR-initiated cell signaling. Hence, our study identifies ALCAM as a novel negative regulator of myeloma pathogenesis.

The Clinical and Theranostic Values of Activated Leukocyte Cell Adhesion Molecule (ALCAM)/CD166 in Human Solid Cancers

Simple Summary

ALCAM (activated leukocyte cell adhesion molecule) is an important regulator in human cancers, particularly solid tumours. Its expression in cancer tissues has prognostic values depending on cancer types and is also linked to distant metastases. A truncated form, soluble form of ALCAM (sALCAM) in circulation has been suggested to be a prognostic indicator and a potential therapeutic tool. This article summarises recent findings and progress in ALCAM and its involvement in cancer, with a primary focus on its clinical connections and therapeutic values.

Abstract

Activated leukocyte cell adhesion molecule (ALCAM), also known as CD166, is a cell adhesion protein that is found in multiple cell types. ALCAM has multiple and diverse roles in various physiological and pathological conditions, including inflammation and cancer. There has been compelling evidence of ALCAM’s prognostic value in solid cancers, indicating that it is a potential therapeutic target. The present article overviews the recent findings and progress in ALCAM and its involvement in cancer, with a primary focus on its clinical connections in cancer and therapeutic values.

Autophagy provides a conceptual therapeutic framework for bone metastasis from prostate cancer

Prostate cancer is a common malignant tumor, which can spread to multiple organs in the body. Metastatic disease is the dominant reason of death for patients with prostate cancer. Prostate cancer usually transfers to bone. Bone metastases are related to pathologic fracture, pain, and reduced survival. There are many known targets for prostate cancer treatment, including androgen receptor (AR) axis, but drug resistance and metastasis eventually develop in advanced disease, suggesting the necessity to better understand the resistance mechanisms and consider multi-target medical treatment. Because of the limitations of approved treatments, further research into other potential targets is necessary. Metastasis is an important marker of cancer development, involving numerous factors, such as AKT, EMT, ECM, tumor angiogenesis, the development of inflammatory tumor microenvironment, and defect in programmed cell death. In tumor metastasis, programmed cell death (autophagy, apoptosis, and necroptosis) plays a key role. Malignant cancer cells have to overcome the different forms of cell death to transfer. The article sums up the recent studies on the mechanism of bone metastasis involving key regulatory factors such as macrophages and AKT and further discusses as to how regulating autophagy is crucial in relieving prostate cancer bone metastasis.

ALCAM/CD166: A pleiotropic mediator of cell adhesion, stemness and cancer progression

Activated Leukocyte Cell Adhesion Molecule (ALCAM/CD166) is a glycoprotein involved in homotypic and heterotypic cell adhesion. ALCAM can be proteolytically cleaved at the cell surface by metalloproteases, which generate shedding of its ectodomain. In various tumors, ALCAM is overexpressed and serves as a valuable prognostic marker of disease progression. Moreover, CD166 has been identified as a putative cancer stem cell marker in particular cancers. Herein, we summarize biochemical aspects of ALCAM, including structure, proteolytic shedding, alternative splicing, and specific ligands, and integrate this information with biological functions of this glycoprotein including cell adhesion, migration and invasion. In addition, we discuss different patterns of ALCAM expression in distinct tumor types and its contribution to tumor progression. Finally, we highlight the role of ALCAM as a cancer stem cell marker and introduce current clinical trials associated with this molecule. Future studies are needed to define the value of shed ALCAM in biofluids or ALCAM isoform expression as prognostic biomarkers in tumor progression.

Chimeric Antigen Receptor T-Cell Therapy: The Light of Day for Osteosarcoma

Simple Summary

As a novel immunotherapy, chimeric antigen receptor (CAR) T-cell therapy has achieved encouraging results in leukemia and lymphoma. Furthermore, CAR-T cells have been explored in the treatment of osteosarcoma (OS). However, there is no strong comprehensive evidence to support their efficacy. Therefore, we reviewed the current evidence on CAR-T cells for OS to demonstrate their feasibility and provide new options for the treatment of OS.

Abstract

Osteosarcoma (OS) is the most common malignant bone tumor, arising mainly in children and adolescents. With the introduction of multiagent chemotherapy, the treatments of OS have remarkably improved, but the prognosis for patients with metastases is still poor, with a five-year survival rate of 20%. In addition, adverse effects brought by traditional treatments, including radical surgery and systemic chemotherapy, may seriously affect the survival quality of patients. Therefore, new treatments for OS await exploitation. As a novel immunotherapy, chimeric antigen receptor (CAR) T-cell therapy has achieved encouraging results in treating cancer in recent years, especially in leukemia and lymphoma. Furthermore, researchers have recently focused on CAR-T therapy in solid tumors, including OS. In this review, we summarize the safety, specificity, and clinical transformation of the targets in treating OS and point out the direction for further research.

CD166 promotes the cancer stem-like properties of primary epithelial ovarian cancer cells

Cancer stem cells (CSCs) or tumor-initiating cells are thought to play critical roles in tumorigenesis, metastasis, drug resistance, and tumor recurrence. For the diagnosis and targeted therapy of CSCs, the molecular identity of biomarkers or therapeutic targets for CSCs needs to be clarified. In this study, we identified CD166 as a novel marker expressed in the sphere-forming CSC population of A2780 epithelial ovarian cancer cells and primary ovarian cancer cells. The CD166⁺ cells isolated from A2780 cells and primary ovarian cancer cells highly expressed CSC markers, including ALDH1a1, OCT4, and SOX2, and ABC transporters, which are implicated in the drug resistance of CSCs. The CD166⁺ cells exhibited enhanced CSC-like properties, such as increased sphere-forming ability, cell migration and adhesion abilities, resistance to conventional anti-cancer drugs, and high tumorigenic potential in a xenograft mouse model. Knockdown of CD166 expression in the sphere-forming ovarian CSCs abrogated their CSC-like properties. Moreover, silencing of CD166 expression in the sphere-forming CSCs suppressed the phosphorylation of focal adhesion kinase, paxillin, and SRC. These results suggest that CD166 plays a key role in the regulation of CSC-like properties and focal adhesion kinase signaling in ovarian cancer.

Up-regulation of pro-angiogenic molecules and events does not relate with an angiogenic switch in metastatic osteosarcoma cells but to cell survival features

Osteosarcoma (OS) is the most frequent malignant bone tumor, affecting predominantly children. Metastases represent a major clinical challenge and an estimated 80% would present undetectable micrometastases at diagnosis. The identification of metastatic traits and molecules would impact in micrometastasis management. We demonstrated that OS LM7 metastatic cells secretome was able to induce microvascular endothelium cell rearrangements, an angiogenic-related trait. A proteomic analysis indicated a gain in angiogenic-related pathways in these cells, as compared to their parental-non-metastatic OS SAOS2 cells counterpart. Further, factors with proangiogenic functions like VEGF and PDGF were upregulated in LM7 cells. However, no differential angiogenic response was induced by LM7 cells in vivo. Regulation of the Fas-FasL axis is key for OS cells to colonize the lungs in this model. Analysis of the proteomic data with emphasis in apoptosis pathways and related processes revealed that the percentage of genes associated with those, presented similar levels in SAOS2 and LM7 cells. Further, the balance of expression levels of proteins with pro- and antiapoptotic functions in both cell types was subtle. Interestingly and of relevance to the model, Fas associated Factor 1 (FAF1), which participates in Fas signaling, was present in LM7 cells and was not detected in SAOS2 cells. The subtle differences in apoptosis-related events and molecules, together with the reported cell-survival functions of the identified angiogenic factors and the increased survival features that we observed in LM7 cells, suggest that the gain in angiogenesis-related pathways in metastatic OS cells would relate to a prosurvival switch rather to an angiogenic switch as an advantage feature to colonize the lungs. OS metastatic cells also displayed higher adhesion towards microvascular endothelium cells suggesting an advantage for tissue colonization. A gain in angiogenesis pathways and molecules does not result in major angiogenic potential. Together, our results suggest that metastatic OS cells would elicit signaling associated to a prosurvival phenotype, allowing homing into the hostile site for metastasis. During the gain of metastatic traits process, cell populations displaying higher adhesive ability to microvascular endothelium, negative regulation of the Fas-FasL axis in the lung parenchyma and a prosurvival switch, would be selected. This opens a new scenario where antiangiogenic treatments would affect cell survival rather than angiogenesis, and provides a molecular panel of expression that may help in distinguishing OS cells with different metastatic potential.

Therapeutic Strategies for Targeting Ovarian Cancer Stem Cells

Ovarian cancer is a fatal gynecological malignancy. Although first-line chemotherapy and surgical operation are effective treatments for ovarian cancer, its clinical management remains a challenge owing to intrinsic or acquired drug resistance and relapse at local or distal lesions. Cancer stem cells (CSCs) are a small subpopulation of cells inside tumor tissues, and they can self-renew and differentiate. CSCs are responsible for the cancer malignancy involved in relapses as well as resistance to chemotherapy and radiation. These malignant properties of CSCs are regulated by cell surface receptors and intracellular pluripotency-associated factors triggered by internal or external stimuli from the tumor microenvironment. The malignancy of CSCs can be attenuated by individual or combined restraining of cell surface receptors and intracellular pluripotency-associated factors. Therefore, targeted therapy against CSCs is a feasible therapeutic tool against ovarian cancer. In this paper, we review the prominent roles of cell surface receptors and intracellular pluripotency-associated factors in mediating the stemness and malignancy of ovarian CSCs.

Human myeloma cell- and plasma-derived extracellular vesicles contribute to functional regulation of stromal cells

Circulating small extracellular vesicles (sEV) represent promising non-invasive biomarkers that may aid in the diagnosis and risk-stratification of multiple myeloma (MM), an incurable blood cancer. Here, we comprehensively isolated and characterized sEV from human MM cell lines (HMCL) and patient-derived plasma (psEV) by specific EV-marker enrichment and morphology. Importantly, we demonstrate that HMCL-sEV are readily internalised by stromal cells to functionally modulate proliferation. psEV were isolated using various commercial approaches and pre-analytical conditions (collection tube types, storage conditions) assessed for sEV yield and marker enrichment. Functionally, MM-psEV was shown to regulate stromal cell proliferation and migration. In turn, pre-educated stromal cells favour HMCL adhesion. psEV isolated from patients with both pre-malignant plasma cell disorders (monoclonal gammopathy of undetermined significance [MGUS]; smouldering MM [SMM]) and MM have a similar ability to promote cell migration and adhesion, suggesting a role for both malignant and pre-malignant sEV in disease progression. Proteomic profiling of MM-psEV (305 proteins) revealed enrichment of oncogenic factors implicated in cell migration and adhesion, in comparison to non-disease psEV. This study describes a protocol to generate morphologically-intact and biologically functional sEV capable of mediating the regulation of stromal cells, and a model for the characterization of tumour-stromal cross-talk by sEV in MM.

Multifaceted effects of soluble human CD6 in experimental cancer models

Background

CD6 is a lymphocyte surface co-receptor physically associated with the T-cell receptor (TCR)/CD3 complex at the center of the immunological synapse. There, CD6 assists in cell-to-cell contact stabilization and modulation of activation/differentiation events through interaction with CD166/ALCAM (activated leukocyte cell adhesion molecule), its main reported ligand. While accumulating evidence is attracting new interest on targeting CD6 for therapeutic purposes in autoimmune disorders, little is known on its potential in cancer. In an attempt to elucidate the in vivo relevance of blocking CD6-mediated interactions in health and disease, we explored the consequences of expressing high circulating levels of a soluble form CD6 (sCD6) as a decoy receptor.

Methods

High sCD6 serum levels were achieved by using transgenic C57BL/6 mice expressing human sCD6 under the control of lymphoid-specific transcriptional elements (shCD6LckEμTg) or wild type either transduced with hepatotropic adeno-associated virus coding for mouse sCD6 or undergoing repeated infusions of recombinant human sCD6 protein. Characterization of sCD6-induced changes was performed by ex vivo flow cytometry and functional analyses of mouse lymphoid organ cells. The in vivo relevance of those changes was explored by challenging mice with subcutaneous or metastatic tumors induced by syngeneic cancer cells of different lineage origins.

Results

Through a combination of in vitro and in vivo studies, we show that circulating sCD6 expression induces defective regulatory T cell (Treg) generation and function, decreased CD166/ALCAM-mediated tumor cell proliferation/migration and impaired galectin-induced T-cell apoptosis, supporting the fact that sCD6 modulates antitumor lymphocyte effector function and tumorigenesis. Accordingly, sCD6 expression in vivo resulted in delayed subcutaneous tumor growth and/or reduced metastasis on challenge of mice with syngeneic cancer cells.

Conclusions

Evidence is provided for the disruption of CD6 receptor–ligand interactions as a feasible immunomodulatory approach in cancer.

Cytokines and Chemokines as Mediators of Prostate Cancer Metastasis

The consequences of prostate cancer metastasis remain severe, with huge impact on the mortality and overall quality of life of affected patients. Despite the convoluted interplay and cross talk between various cell types and secreted factors in the metastatic process, cytokine and chemokines, along with their receptors and signaling axis, constitute important factors that help drive the sequence of events that lead to metastasis of prostate cancer. These proteins are involved in extracellular matrix remodeling, epithelial-mesenchymal-transition, angiogenesis, tumor invasion, premetastatic niche creation, extravasation, re-establishment of tumor cells in secondary organs as well as the remodeling of the metastatic tumor microenvironment. This review presents an overview of the main cytokines/chemokines, including IL-6, CXCL12, TGFβ, CXCL8, VEGF, RANKL, CCL2, CX3CL1, IL-1, IL-7, CXCL1, and CXCL16, that exert modulatory roles in prostate cancer metastasis. We also provide extensive description of their aberrant expression patterns in both advanced disease states and metastatic sites, as well as their functional involvement in the various stages of the prostate cancer metastatic process.

Dual in vitro invasion/migration suppressing and tamoxifen response modulating effects of a recombinant anti-ALCAM scFv on breast cancer cells

It has been shown that overexpression of activated leukocyte cell adhesion molecule (ALCAM) is involved in development of resistance to tamoxifen therapy and promotion of cell invasion, migration and metastasis in ER+ breast cancer cells. Thus, we hypothesized that blockade of ALCAM interconnections with antibodies could be an effective approach for reversing mentioned negative events associated with ALCAM overexpression in breast cancer cells. Here, an anti-ALCAM scFv was recombinantly expressed and used throughout study for examination of the putative anticancer effects of ALCAM blockade. The anti-ALCAM scFv coding sequence was obtained from GenBank database and after addition of a 6× His-tag moiety, signal peptide and flanking sequences, the whole construct was expressed in Escherichia coli. Tamoxifen resistant MCF7 cells were then pretreat for 24 hours with purified recombinant anti-ALCAM scFv prior to administration of tamoxifen. In parallel, the cytotoxicity profile of anti-ALCAM scFv and tamoxifen co-treatments against tamoxifen resistant and sensitive MCF7 cell lines was also evaluated using CompuSyn software. The invasion/migration inhibitory effects of anti-ALCAM scFv on MDA-MB-231 cells were also evaluated. Pretreatment with anti-ALCAM scFv could successfully enhance anti-proliferative effects of tamoxifen against resistant MCF-7 cell lines. Furthermore, the combination of 19.2:1 of tamoxifen to anti-ALCAM scFv demonstrated synergistic cell inhibitory effect against tamoxifen resistant MCF7 cell lines. Also, incubating MDA-MB-231 cell lines with anti-ALCAM scFv resulted in a 30% and 25% reduction in number of invaded and migrated cells respectively. Overall, application of anti-ALCAM scFv could significantly suppress cancer cells metastasis in vitro and modulate tamoxifen resistant ER+ MCF7 cell line's sensitivity to tamoxifen. SIGNIFICANCE OF THE STUDY: Acquisition of resistance to tamoxifen therapy is one of the major challenges associated with cancer chemotherapy, gradually turning a responsive tumour into a refractory more invasive one which ultimately ends in disease progression and relapse. Here, we reported expression of an anti-ALCAM scFv, capable of increasing the sensitivity of tamoxifen resistant ER+ MCF-7 cells to tamoxifen therapy following a 24-hour pretreatment period. In addition, we demonstrated that the anti-ALCAM scFv monotherapy was also capable of suppressing invasion and migration of MDA-MB-231 cells in Boyden chamber assays.

S100 Soil Sensor Receptors and Molecular Targeting Therapy Against Them in Cancer Metastasis

The molecular mechanisms underlying the ‘seed and soil’ theory are unknown. S100A8/A9 (a heterodimer complex of S100A8 and S100A9 proteins that exhibits a ‘soil signal’) is a ligand for Toll-like receptor 4, causing distant melanoma cells to approach the lung as a ‘seeding’ site. Unknown soil sensors for S100A8/A9 may exist, e.g., extracellular matrix metalloproteinase inducer, neuroplastin, activated leukocyte cell adhesion molecule, and melanoma cell adhesion molecule. We call these receptor proteins ‘novel S100 soil sensor receptors (novel SSSRs).’ Here we review and summarize a crucial role of the S100A8/A9-novel SSSRs' axis in cancer metastasis. The binding of S100A8/A9 to individual SSSRs is important in cancer metastasis via upregulations of the epithelial-mesenchymal transition, cellular motility, and cancer cell invasiveness, plus the formation of an inflammatory immune suppressive environment in metastatic organ(s). These metastatic cellular events are caused by the SSSR-featured signal transductions we identified that provide cancer cells a driving force for metastasis. To deprive cancer cells of these metastatic forces, we developed novel biologics that prevent the interaction of S100A8/A9 with SSSRs, followed by the efficient suppression of S100A8/A9-mediated lung-tropic metastasis in vivo.

Upregulation of miR-630 Induced by Oxidative Damage Resists Cell Migration Through Targeting ALCAM in Human Lens Epithelium Cells

Purpose: To investigate the role of miRNAs in regulating oxidative damage during cataract formation.Methods: Microarray analysis and gene expression profiling assay were used to separately evaluate the miRNAs and mRNAs profiles in normal human lens epithelium cell line HLE-B3 treated by H₂O₂. The expression level of miR-630 was detected by RT-qPCR and the gene expression profiles were performed with gene ontology analysis using Bio Informatical database. The targets of miR-630 were predicted using miRecords and the results were used for screening targets of miR-630 combined with the GO analysis above. The mRNA levels of ALCAM, PCDH7, COL12A2, and EDIL3 in HLE-B3 cells after oxidative stimulation or miR-630 mimics transfection were measured by RT-qPCR, and the expression of ALCAM regulated by miR-630 was confirmed by Western blot and dual-luciferase reporter gene assay. The level of cell migration was measured by transwell assay and scratching test after transfection of miR-630 mimics and ALCAM siRNAs.Results: The microarray analysis demonstrated that miR-630 was significantly increased in HLE-B3 cells after oxidative stimulation. ALCAM, PCDH7, COL12A2, and EDIL3 were screened to be the possible targets of miR-630 by miRecords combined with GO analysis, but the results of RT-qPCR, Western blot and dual-luciferase reporter gene assay showed that only the expression of ALCAM was repressed by miR-630 transfection. Cell migration was inhibited through transfection of miR-630 mimics or ALCAM siRNAs and the upregulation of miR-630 partly reduced the cell migration increased by oxidative stimulation.Conclusion: miR-630 is one of the miRNAs increased by oxidative stimulation in human lens epithelium cells. Its upregulation may inhibit cell migration by targeting on ALCAM, which is important for HLECs to resist behavioral changes induced by oxidative damage and may delay the progression of cataract.

The tumor immune microenvironment in gastroenteropancreatic neuroendocrine neoplasms

Gastroenteropancreatic neuroendocrine neoplasms (GEP-NENs) are a group of rare tumors that are increasing in prevalence. The complex tumor immune microenvironment (TIME) plays an important role in tumor development and the response to immunotherapy but is poorly understood. In this review, the components of the TIME are described in detail, including discussion about infiltrating immune cells, the immune checkpoint system, the cytokine and chemokine milieu, and immunomodulatory factors. Moreover, a comparison between TIMEs among different types of GEP-NENs and the interplay among the TIME, tumor cells, and the stromal microenvironment is described. Novel treatment options for GEP-NENs and potential biomarkers for the immune response are also characterized. We provide a comprehensive generalized review of the TIME that can inform GEP-NEN treatment strategies.

Integrated bioinformatics analysis of miRNA expression in Ewing sarcoma and potential regulatory effects of miR-21 via targeting ALCAM/CD166

MicroRNAs (miRNAs) play essential functions in pathogenesis of Ewing sarcoma (ES). However, the molecular mechanisms responsible for ES occurrence and development through the regulation of miRNAs remain largely unknown. This study is aimed to explore the differential expressed miRNAs and mRNAs that play vital roles in ES. GSE80201 miRNA and GSE68776 mRNA microarray dataset were selected to carry out a series of bioinformatics analysis such as GEO 2R, gene ontology, pathway enrichment analysis, Venn analysis and PPI network construction to predict hub genes. Furthermore, using quantitative real-time PCR, RNA interference and luciferase reporter assay we demonstrated that activated leukocyte cell adhesion molecule (ALCAM/CD166) is a direct target of miR-21-3p in human ES cell lines. Our results suggest that the miR-21/CD166 axis has the potential to serve as both diagnostic markers and therapeutic targets for ES.

Importance of activated leukocyte cell adhesion molecule (ALCAM) in prostate cancer progression and metastatic dissemination

Activated Leukocyte Cell Adhesion Molecule (ALCAM) has been linked to the progression of numerous human cancers, where it appears to play a complex role. The current study aims to further assess the importance of ALCAM in prostate cancer and the prognostic potential of serum ALCAM as a biomarker for prostate cancer progression. Here we demonstrate enhanced levels of tissue ALCAM are associated with metastasis. Additionally, elevated serum ALCAM is indicative of progression and poorer patient outlook, and demonstrates comparable prognostic ability to PSA in terms of metastasis and prostate cancer survival. ALCAM suppression enhanced proliferation and invasiveness in PC-3 cells and motility/migration in PC-3 and LNCaP cells. ALCAM suppressed PC-3 cells were generally less responsive to HGF and displayed reduced MET transcript expression. Furthermore a recombinant human ALCAM-Fc chimera was able to inhibit LNCaP cell attachment to HECV and hFOB1.19 cells. Taken together, ALCAM appears to be a promising biomarker for prostate cancer progression, with enhanced serum expression associated with poorer prognosis. Suppression of ALCAM appears to impact cell function and cellular responsiveness to certain micro environmental factors.

Activated Leukocyte Cell Adhesion Molecule Stimulates the T-Cell Response in Allergic Asthma

RATIONALE

The activated leukocyte cell adhesion molecule (ALCAM) is a cluster of differentiation 6 ligand that is important for stabilizing the immunological synapse and inducing T-cell activation and proliferation.

OBJECTIVES

In this study, we investigated the role of ALCAM in the development of inflammation in allergic asthma.

METHODS

An ovalbumin (OVA)-induced allergic asthma model was established in wild-type (WT) and ALCAM-deficient (ALCAM^-/-) mice. T-cell proliferation was evaluated in cocultures with dendritic cells (DCs). Bone marrow-derived dendritic cells (BMDCs) from WT and ALCAM^-/- mice were cultured and adoptively transferred to OT-II mice for either OVA sensitization or challenge. An anti-ALCAM antibody was administered to assess its therapeutic potential. ALCAM concentrations in the sputum and serum of children with asthma were quantified by ELISA.

MEASUREMENTS AND MAIN RESULTS

Inflammatory responses were lower in ALCAM^-/- mice than in WT mice, and T cells cocultured with DCs from ALCAM^-/- mice showed reduced proliferation relative to those cocultured with DCs from WT mice. A decreased inflammatory response was observed upon adoptive transfer of BMDCs from ALCAM^-/- mice as compared with that observed after transfer of BMDCs from WT mice. In addition, anti-ALCAM antibody-treated mice showed a reduced inflammatory response, and sputum and serum ALCAM concentrations were higher in children with asthma than in control subjects.

CONCLUSIONS

ALCAM contributes to OVA-induced allergic asthma by stimulating T-cell activation and proliferation, suggesting it as a potential therapeutic target for allergic asthma.

Dual knockdown of Galectin-8 and its glycosylated ligand, the activated leukocyte cell adhesion molecule (ALCAM/CD166), synergistically delays in vivo breast cancer growth

Galectin-8 (Gal-8), a 'tandem-repeat'-type galectin, has been described as a modulator of cellular functions including adhesion, spreading, growth arrest, apoptosis, pathogen recognition, autophagy, and immunomodulation. We have previously shown that activated leukocyte cell adhesion molecule (ALCAM), also known as CD166, serves as a receptor for endogenous Gal-8. ALCAM is a member of the immunoglobulin superfamily involved in cell-cell adhesion through homophilic (ALCAM-ALCAM) and heterophilic (i.e. ALCAM-CD6) interactions in different tissues. Here we investigated the physiologic relevance of ALCAM-Gal-8 association and glycosylation-dependent mechanisms governing these interactions. We found that silencing of ALCAM in MDA-MB-231 triple negative breast cancer cells decreases cell adhesion and migration onto Gal-8-coated surfaces in a glycan-dependent fashion. Remarkably, either Gal-8 or ALCAM silencing also disrupted cell-cell adhesion, and led to reduced tumor growth in a murine model of triple negative breast cancer. Moreover, structural characterization of endogenous ALCAM N-glycosylation showed abundant permissive structures for Gal-8 binding. Importantly, we also found that cell sialylation controls Gal-8-mediated cell adhesion. Altogether, these findings demonstrate a central role of either ALCAM or Gal-8 (or both) in controlling triple negative breast cancer.

Cellular and Molecular Mechanisms Underlying Prostate Cancer Development: Therapeutic Implications

Prostate cancer is the most frequent nonskin cancer and second most common cause of cancer-related deaths in man. Prostate cancer is a clinically heterogeneous disease with many patients exhibiting an aggressive disease with progression, metastasis, and other patients showing an indolent disease with low tendency to progression. Three stages of development of human prostate tumors have been identified: intraepithelial neoplasia, adenocarcinoma androgen-dependent, and adenocarcinoma androgen-independent or castration-resistant. Advances in molecular technologies have provided a very rapid progress in our understanding of the genomic events responsible for the initial development and progression of prostate cancer. These studies have shown that prostate cancer genome displays a relatively low mutation rate compared with other cancers and few chromosomal loss or gains. The ensemble of these molecular studies has led to suggest the existence of two main molecular groups of prostate cancers: one characterized by the presence of ERG rearrangements (~50% of prostate cancers harbor recurrent gene fusions involving ETS transcription factors, fusing the 5' untranslated region of the androgen-regulated gene TMPRSS2 to nearly the coding sequence of the ETS family transcription factor ERG) and features of chemoplexy (complex gene rearrangements developing from a coordinated and simultaneous molecular event), and a second one characterized by the absence of ERG rearrangements and by the frequent mutations in the E3 ubiquitin ligase adapter SPOP and/or deletion of CDH1, a chromatin remodeling factor, and interchromosomal rearrangements and SPOP mutations are early events during prostate cancer development. During disease progression, genomic and epigenomic abnormalities accrued and converged on prostate cancer pathways, leading to a highly heterogeneous transcriptomic landscape, characterized by a hyperactive androgen receptor signaling axis.

Co-detection of ALDH1A1, ABCG2, ALCAM and CD133 in three A549 subpopulations at the single cell level by one-step digital RT-PCR

Cancer stem-like cells (CSCs) displaying the properties of normal stem cells have become the main culprit associated with cancer transportation and recurrence. As of now, various CSC functions and marker genes have been identified due to the heterogeneity of cancer, such as aldehyde dehydrogenase (ALDH), the second member of the ABC transporter G-subfamily (ABCG2), activated leukocyte cell adhesion molecule (ALCAM) and CD133. To investigate these markers, most conventional approaches are bulk-based strategies, which may veil the disparity of single cells' gene expression. In this study, one-step digital RT-PCR at the single cell level was developed to co-determine the expression of ALDH1A1, ABCG2, ALCAM and CD133 genes in A549 cancer stem cells that perform high ALDH activities (ALDH+ A549 cells), as well as in ALDH- A549 cells and A549 cells, with 36, 20 and 20 cell samples each. The results demonstrated that, when compared to single ALDH- or A549 cells, the majority of single ALDH+ A549 cells displayed a 1.5- and 2.0-fold increase in the gene expression of ALDH1A1 and ALCAM (P < 0.001), respectively. However, for ABCG2 and CD133, there was no significant difference (P > 0.05), which means that they are not appropriate as co-indicated markers to identify ALDH+ A549 cells. Conclusively, as a single cell level approach, one-step digital RT-PCR has potential in exploring efficient co-detection markers for the classification and identification of CSCs.

Modulation of cell adhesion and migration through regulation of the immunoglobulin superfamily member ALCAM/CD166

In epithelial-derived cancers, altered regulation of cell-cell adhesion facilitates the disruption of tissue cohesion that is central to the progression to malignant disease. Although numerous intercellular adhesion molecules participate in epithelial adhesion, the immunoglobulin superfamily (IgSF) member activated leukocyte cell adhesion molecule (ALCAM), has emerged from multiple independent studies as a central contributor to tumor progression. ALCAM is an archetypal member of the IgSF with conventional organization of five Ig-like domains involved in homo- and heterotypic adhesions. Like many IgSF members, ALCAM is broadly expressed and involved in cellular adhesion across many cellular processes. While the redundancy of intercellular adhesion molecules (CAMs) could diminish the impact of any single CAM, consistent correlation between ALCAM expression and patient outcome for multiple cancers underscores its role in tumor progression. Unlike most oncogenes and tumor suppressors, ALCAM is neither mutated nor amplified or deleted. Experimental disruption of ALCAM-mediated adhesions implies that this IgSF member contributes to tumor progression through dynamic turnover of the protein at the cell surface. Since ALCAM is not frequently altered at the gene level, it appears to promote malignant behavior through regulation of its availability rather than its specific activity. These observations help explain its heterogeneous expression within malignant disease and the drastic changes in protein levels across tumor progression. To reveal how ALCAM contributes to tumor progression, we review regulation of its gene expression, alternative splicing, targeted proteolysis, binding partners, and surface shedding within the context of cancer. Studying ALCAM regulation has led to a novel understanding of the fine-tuning of cell adhesive state through the utilization of otherwise normal regulatory processes, which thereby enable tumor cell invasion and metastasis.

Metastatic cancer cells compensate for low energy supplies in hostile microenvironments with bioenergetic adaptation and metabolic reprogramming

Metastasis accounts for the majority of cancer-related mortalities, and the complex processes of metastasis remain the least understood aspect of cancer biology. Metabolic reprogramming is associated with cancer cell survival and metastasis in a hostile envi-ronment with a limited nutrient supply, such as solid tumors. Little is known regarding the differences of bioenergetic adaptation between primary tumor cells and metastatic tumor cells in unfavorable microenvironments; to clarify these differences, the present study aimed to compare metabolic reprogramming of primary tumor cells and metastatic tumor cells. SW620 metastatic tumor cells exhibited stronger bioenergetic adaptation in unfavorable conditions compared with SW480 primary tumor-derived cells, as determined by the sustained elevation of glycolysis and regulation of the cell cycle. This remarkable glycolytic ability of SW620 cells was associated with high expression levels of hexokinase (HK)1, HK2, glucose transporter type 1 and hypoxia-inducible factor 1α. Compared with SW480 cells, the expression of cell cycle regulatory proteins was effectively inhibited in SW620 cells to sustain cell survival when there was a lack of energy. Furthermore, SW620 cells exhibited a stronger mesenchymal phenotype and stem cell characteristics compared with SW480 cells; CD133 and CD166 were highly expressed in SW620 cells, whereas expression was not detected in SW480 cells. These data may explain why metastatic cancer cells exhibit greater microenvironmental adaptability and survivability; specifically, this may be achieved by upregulating glycolysis, optimizing the cell cycle and reprogramming cell metabolism. The present study may provide a target metabolic pathway for cancer metastasis therapy.

A homing system targets therapeutic T cells to brain cancer

Successful T cell immunotherapy for brain cancer requires that the T cells can access tumour tissues, but this has been difficult to achieve. Here we show that, in contrast to inflammatory brain diseases such as multiple sclerosis, where endothelial cells upregulate ICAM1 and VCAM1 to guide the extravasation of pro-inflammatory cells, cancer endothelium downregulates these molecules to evade immune recognition. By contrast, we found that cancer endothelium upregulates activated leukocyte cell adhesion molecule (ALCAM), which allowed us to overcome this immune-evasion mechanism by creating an ALCAM-restricted homing system (HS). We re-engineered the natural ligand of ALCAM, CD6, in a manner that triggers initial anchorage of T cells to ALCAM and conditionally mediates a secondary wave of adhesion by sensitizing T cells to low-level ICAM1 on the cancer endothelium, thereby creating the adhesion forces necessary to capture T cells from the bloodstream. Cytotoxic HS T cells robustly infiltrated brain cancers after intravenous injection and exhibited potent antitumour activity. We have therefore developed a molecule that targets the delivery of T cells to brain cancer.

Shed urinary ALCAM is an independent prognostic biomarker of three-year overall survival after cystectomy in patients with bladder cancer

Proteins involved in tumor cell migration can potentially serve as markers of invasive disease. Activated Leukocyte Cell Adhesion Molecule (ALCAM) promotes adhesion, while shedding of its extracellular domain is associated with migration. We hypothesized that shed ALCAM in biofluids could be predictive of progressive disease. ALCAM expression in tumor (n = 198) and shedding in biofluids (n = 120) were measured in two separate VUMC bladder cancer cystectomy cohorts by immunofluorescence and enzyme-linked immunosorbent assay, respectively. The primary outcome measure was accuracy of predicting 3-year overall survival (OS) with shed ALCAM compared to standard clinical indicators alone, assessed by multivariable Cox regression and concordance-indices. Validation was performed by internal bootstrap, a cohort from a second institution (n = 64), and treatment of missing data with multiple-imputation. While ALCAM mRNA expression was unchanged, histological detection of ALCAM decreased with increasing stage (P = 0.004). Importantly, urine ALCAM was elevated 17.0-fold (P < 0.0001) above non-cancer controls, correlated positively with tumor stage (P = 0.018), was an independent predictor of OS after adjusting for age, tumor stage, lymph-node status, and hematuria (HR, 1.46; 95% CI, 1.03–2.06; P = 0.002), and improved prediction of OS by 3.3% (concordance-index, 78.5% vs. 75.2%). Urine ALCAM remained an independent predictor of OS after accounting for treatment with Bacillus Calmette-Guerin, carcinoma in situ, lymph-node dissection, lymphovascular invasion, urine creatinine, and adjuvant chemotherapy (HR, 1.10; 95% CI, 1.02–1.19; P = 0.011). In conclusion, shed ALCAM may be a novel prognostic biomarker in bladder cancer, although prospective validation studies are warranted. These findings demonstrate that markers reporting on cell motility can act as prognostic indicators.

Activated leucocyte cell adhesion molecule (ALCAM/CD166) regulates T cell responses in a murine model of food allergy

Food allergy is a major public health problem. Studies have shown that long-term interactions between activated leucocyte cell adhesion molecule (ALCAM/CD166) on the surface of antigen-presenting cells, and CD6, a co-stimulatory molecule, influence immune responses. However, there are currently no studies on the functions of ALCAM in food allergy. Therefore, we aimed to identify the functions of ALCAM in ovalbumin (OVA)-induced food allergy using ALCAM-deficient mice. Wild-type (WT) and ALCAM-deficient (ALCAM^-/- ) mice were sensitized intraperitoneally and with orally fed OVA. The mice were killed, and parameters related to food allergy and T helper type 2 (Th2) immune responses were analysed. ALCAM serum levels increased and mRNA expression decreased in OVA-challenged WT mice. Serum immunoglobulin (Ig)E levels, Th2 cytokine mRNA and histological injuries were higher in OVA-challenged WT mice than in control mice, and these were attenuated in ALCAM^-/- mice. T cell proliferation of total cells, CD3⁺ CD4⁺ T cells and activated T cells in immune tissues were diminished in OVA-challenged ALCAM^-/- mice. Proliferation of co-cultured T cells and dendritic cells (DCs) was decreased by the anti-CD6 antibody. In addition, WT mice sensitized by adoptive transfer of OVA-pulsed ALCAM^-/- BM-derived DCs showed reduced immune responses. Lastly, serum ALCAM levels were higher in children with food allergy than in control subjects. In this study, serum levels of ALCAM were elevated in food allergy-induced WT mice and children with food allergy. Moreover, immune responses and T cell activation were attenuated in OVA-challenged ALCAM^-/- mice. These results indicate that ALCAM regulates food allergy by affecting T cell activation.

Alternative splicing of ALCAM enables tunable regulation of cell-cell adhesion through differential proteolysis

While many adhesion receptors are known to influence tumor progression, the mechanisms by which they dynamically regulate cell-cell adhesion remain elusive. We previously identified Activated Leukocyte Cell Adhesion Molecule (ALCAM) as a clinically relevant driver of metastasis and hypothesized that a tunable mechanism of ectodomain shedding regulates its contribution to dissemination. To test this hypothesis, we examined an under-explored ALCAM splice variant (ALCAM-Iso2) and demonstrated that loss of the membrane-proximal region of ALCAM (exon 13) increased metastasis four-fold. Mechanistic studies identified a novel MMP14-dependent membrane distal cleavage site in ALCAM-Iso2, which mediated a ten-fold increase in shedding, thereby decreasing cellular cohesion. Importantly, the loss of cohesion is not limited to the cell capable of shedding because the released extracellular domain diminished cohesion of non-shedding cells through disruption of ALCAM-ALCAM interactions. ALCAM-Iso2-dominated expression in bladder cancer tissue, compared to normal bladder, further emphasizes that ALCAM alternative splicing may contribute to clinical disease progression. The requirement for both the loss of exon 13 and the gain of metalloprotease activity suggests that ALCAM shedding and concomitant regulation of tumor cell adhesion is a locally tunable process.

Characterization of prostate cancer cell progression in zebrafish xenograft model

Early diagnosis of prostate cancer (PCa) is critical for the application of efficient treatment to PCa patients. However, the majority of PCas remains indolent from several months to several years before malignancy. Current diagnosis methods have limitations in their reliability and are inefficient in time cost. Thus, an efficient in vivo PCa cell xenograft model is highly desired for diagnostic studies in PCas. In the present study we present a standardized procedure to create a PCa cell xenograft model using zebrafish (Danio rerio) as the host. PC3-CTR cells, a cell line from adenocarcinoma with stable expression of calcitonin receptor (CRT), were subcutaneously injected into zebrafish larvae at 48 h post fertilization. The nursing conditions for the larvae were optimized with stable survival rates of post hatch and post PC3-CTR cell injection. In this system, the progression of PC3-CTR cells in vivo was evaluated by migration and proliferation of the cells. Massive migrations of PC3 cells in vivo were observed at post injection day (PID)3. The injected PC3-CTR cells eventually invaded the whole larval zebrafish at PID5. Quantification of PC3-CTR cell proliferation was done using quantitative PCR (qPCR) analysis targeting the expression profiles of two PCa housekeeping genes, TATA-binding protein (TBP) and hypoxanthine phosphoribosyltransferase 1 (HPRT1) encoding genes. The excessive proliferation of PC3 cells in vivo was detected with both qPCR assays. Expression levels of one non-coding gene, prostate cancer associated 3 gene (pca3), and two other genes encoding transient receptor potential ion channel Melastatin 8 (trpm8) and prostate-specific membrane antigen (psma), showed a significantly enhanced aggressiveness of PC3-CTR cells in vivo. The model established in the present study provides an improved in vivo model for the diagnosis of PCas efficiently. This PCa cell xenograft model can also serve as a tool for high throughput anti-PCa drug screening in therapeutic treatments.

Stromal and epithelial transcriptional map of initiation progression and metastatic potential of human prostate cancer

While progression from normal prostatic epithelium to invasive cancer is driven by molecular alterations, tumor cells and cells in the cancer microenvironment are co-dependent and co-evolve. Few human studies to date have focused on stroma. Here, we performed gene expression profiling of laser capture microdissected normal non-neoplastic prostate epithelial tissue and compared it to non-transformed and neoplastic low-grade and high-grade prostate epithelial tissue from radical prostatectomies, each with its immediately surrounding stroma. Whereas benign epithelium in prostates with and without tumor were similar in gene expression space, stroma away from tumor was significantly different from that in prostates without cancer. A stromal gene signature reflecting bone remodeling and immune-related pathways was upregulated in high compared to low-Gleason grade cases. In validation data, the signature discriminated cases that developed metastasis from those that did not. These data suggest that the microenvironment may influence prostate cancer initiation, maintenance, and metastatic progression.Stromal cells contribute to tumor development but the mechanisms regulating this process are still unclear. Here the authors analyze gene expression profiles in the prostate and show that stromal gene signature changes ahead of the epithelial gene signature as prostate cancer initiates and progresses.

Stromal Expression of Activated Leukocyte Cell Adhesion Molecule Promotes Lung Tumor Growth and Metastasis

Activated leukocyte cell adhesion molecule (ALCAM) is expressed on various cell types, including leukocytes, endothelial cells, and certain tumor cells. Although ALCAM expression on tumor cells has been linked to tumor invasion and metastatic spread, the contribution of ALCAM expressed in cells forming the tumor stroma to cancer progression has not been investigated. In this study, ALCAM-deficient (ALCAM^-/-) mice were used to evaluate the role of ALCAM in lung tumor growth and metastasis. ALCAM^-/- mice displayed an altered blood vascular network in the lung and the diaphragm, indicative of an angiogenetic defect. The absence of ALCAM expression in cells forming the stromal tumor microenvironment profoundly affected lung tumor growth in three different i.v. metastasis models. In the case of Lewis lung carcinoma (LLC), an additional defect in tumor cell homing to the lungs and a resulting reduction in the number of lung tumor nodules were observed. Similarly, when LLC cells were implanted subcutaneously for the study of spontaneous tumor cell metastasis, the rate of LLC metastasis to the lungs was profoundly reduced in ALCAM^-/- mice. Taken together, our work demonstrates for the first time the in vivo contribution of ALCAM to angiogenesis and reveals a novel role of stromally expressed ALCAM in supporting tumor growth and metastatic spread.

BOK displays cell death-independent tumor suppressor activity in non-small-cell lung carcinoma

As the genomic region containing the Bcl-2-related ovarian killer (BOK) locus is frequently deleted in certain human cancers, BOK is hypothesized to have a tumor suppressor function. In the present study, we analyzed primary non-small-cell lung carcinoma (NSCLC) tumors and matched lung tissues from 102 surgically treated patients. We show that BOK protein levels are significantly downregulated in NSCLC tumors as compared to lung tissues (p < 0.001). In particular, we found BOK downregulation in NSCLC tumors of grades two (p = 0.004, n = 35) and three (p = 0.031, n = 39) as well as in tumors with metastases to hilar (pN1) (p = 0.047, n = 31) and mediastinal/subcarinal lymph nodes (pN2) (p = 0.021, n = 18) as opposed to grade one tumors (p = 0.688, n = 7) and tumors without lymph node metastases (p = 0.112, n = 51). Importantly, in lymph node-positive patients, BOK expression greater than the median value was associated with longer survival (p = 0.002, Mantel test). Using in vitro approaches, we provide evidence that BOK overexpression is inefficient in inducing apoptosis but that it inhibits TGFβ-induced migration and epithelial-to-mesenchymal transition (EMT) in lung adenocarcinoma-derived A549 cells. We have identified epigenetic mechanisms, in particular BOK promoter methylation, as an important means to silence BOK expression in NSCLC cells. Taken together, our data point toward a novel mechanism by which BOK acts as a tumor suppressor in NSCLC by inhibiting EMT. Consequently, the restoration of BOK levels in low-BOK-expressing tumors might favor the overall survival of NSCLC patients.

The histone demethylase KDM3A, and its downstream target MCAM, promote Ewing Sarcoma cell migration and metastasis

Ewing Sarcoma is the second most common solid pediatric malignant neoplasm of bone and soft tissue. Driven by EWS/Ets, or rarely variant, oncogenic fusions, Ewing Sarcoma is a biologically and clinically aggressive disease with a high propensity for metastasis. However, the mechanisms underpinning Ewing Sarcoma metastasis are currently not well understood. In the present study, we identify and characterize a novel metastasis-promotional pathway in Ewing Sarcoma, involving the histone demethylase KDM3A, previously identified by our laboratory as a new cancer-promoting gene in this disease. Using global gene expression profiling, we show that KDM3A positively regulates genes and pathways implicated in cell migration and metastasis, and demonstrate, using functional assays, that KDM3A promotes migration in vitro and experimental, post-intravasation, metastasis in vivo. We further identify the melanoma cell adhesion molecule (MCAM) as a novel KDM3A target gene in Ewing Sarcoma, and an important effector of KDM3A pro-metastatic action. Specifically, we demonstrate that MCAM depletion, like KDM3A depletion, inhibits cell migration in vitro and experimental metastasis in vivo, and that MCAM partially rescues impaired migration due to KDM3A knock-down. Mechanistically, we show that KDM3A regulates MCAM expression both through a direct mechanism, involving modulation of H3K9 methylation at the MCAM promoter, and an indirect mechanism, via the Ets1 transcription factor. Finally, we identify an association between high MCAM levels in patient tumors and poor survival, in two different Ewing Sarcoma clinical cohorts. Taken together, our studies uncover a new metastasis-promoting pathway in Ewing Sarcoma, with therapeutically targetable components.

ALCAM a novel biomarker in patients with type 2 diabetes mellitus complicated with diabetic nephropathy

BACKGROUND & AIM

Activated leukocyte cell adhesion molecule (ALCAM/CD166) functions analogue to the receptor of advanced glycation end products, which has been implicated in the development of diabetic nephropathy (DN). We investigated the expression of ALCAM and its ligand S100B in patients with DN.

METHODS

A total of 34 non-diabetic patients, 29 patients with type 2 diabetes and normal albuminuria and 107 patients with type 2 diabetes complicated with DN were assessed for serum concentration of soluble ALCAM (sALCAM) by ELISA. Expression of ALCAM and S100B in kidney histology from patients with DN was determined by immunohistochemistry. Cell expression of ALCAM and S100B was analyzed through confocal immunofluorescence microscopy.

RESULTS

Serum concentration of sALCAM was increased in diabetic patients with DN compared to non-diabetic (59.85±14.99ng/ml vs. 126.88±66.45ng/ml, P<0.0001). Moreover sALCAM correlated positively with HbA1c (R=0.31, P<0.0001), as well as with the stages of chronic kidney disease and negatively correlated with eGFR (R=-0.20, P<0.05). In diabetic patients with normal albuminuria sALCAM was increased compared to patients with DN (126.88±66.45ng/ml vs. 197.50±37.17ng/ml, P<0.0001). In diabetic patients, ALCAM expression was significantly upregulated in both the glomeruli and tubules (P<0.001). ALCAM expression in the glomeruli correlated with presence of sclerosis (R=0.25, P<0.001) and localized mainly in the podocytes supporting the hypothesis that membrane bound ALCAM drives diabetic nephropathy and thus explaining sALCAM decrease in diabetic patients with DN. The expression of S100B was increased significantly in the glomeruli of diabetic patients (P<0.001), but not in the tubules. S100B was as well localized in the podocytes.

CONCLUSIONS

This study identifies for the first time ALCAM as a potential mediator in the late complications of diabetes in the kidney.

Extracellular vesicles for liquid biopsy in prostate cancer: where are we and where are we headed?

Background:

Extracellular vesicles (EVs) are a heterogeneous class of lipid bound particles shed by any cell in the body in physiological and pathological conditions. EVs play critical functions in intercellular communication. EVs can actively travel in intercellular matrices and eventually reach the circulation. They can also be released directly in biological fluids where they appear to be stable. Because the molecular content of EVs reflects the composition of the cell of origin, they have recently emerged as a promising source of biomarkers in a number of diseases. EV analysis is particularly attractive in cancer patients that frequently present with increased numbers of circulating EVs.

Methods:

We sought to review the current literature on the molecular profile of prostate cancer-derived EVs in model systems and patient biological fluids in an attempt to draw some practical and universal conclusions on the use of EVs as a tool for liquid biopsy in clinical specimens.

Results:

We discuss advantages and limitations of EV-based liquid biopsy approaches summarizing salient studies on protein, DNA and RNA. Several candidate biomarkers have been identified so far but these results are difficult to apply to the clinic. However, the field is rapidly moving toward the implementation of novel tools to isolate cancer-specific EVs that are free of benign EVs and extra-vesicular contaminants. This can be achieved by identifying markers that are exquisitely present in tumor cell-derived EVs. An important contribution might also derive from a better understanding of EV types that may play specific functions in tumor progression and that may be a source of cancer-specific markers.

Conclusions:

EV analysis holds strong promises for the development of non-invasive biomarkers in patients with prostate cancer. Implementation of modern methods for EV isolation and characterization will enable to interrogate circulating EVs in vivo.