The PTK7 and ROR2 Protein Receptors Interact in the Vertebrate WNT/Planar Cell Polarity (PCP) Pathway

Zinc-Cobalt Bimetallic Organic Frameworks with Antioxidative and Osteogenic Activities for Periodontitis Treatment

Periodontitis is a prolonged inflammatory disease caused by bacterial infection. Oxidative stress induced by inflammation leads to excessive production of reactive oxygen species (ROS) and difficulties in bone tissue regeneration. ROS-scavenging agents regulate the periodontal tissue microenvironment, which is of great significance in the treatment of periodontitis. In this study, a zinc-cobalt bimetallic organic framework (Zn/Co-MOF) is constructed to alleviate local tissue inflammation and bone resorption in periodontitis by cascading antioxidant activity. In vitro experimental results show that the Zn/Co-MOF not only provides effective cellular protection against ROS attack in human bone marrow mesenchymal stem cells and osteoblast precursor cells (MC3T3-E1), but also promotes osteogenic differentiation. In vivo experiments in rat periodontitis models confirm that Zn/Co-MOFs can reduce local periodontal tissue inflammation, reduce osteoclasts, and promote the recovery of alveolar bone height defects, which is beneficial for the treatment of periodontitis. RNA sequencing results show that the Zn/Co-MOF promotes bone tissue regeneration mainly through activated Wnt pathways, which accelerate osteogenic differentiation. Overall, the Zn/Co-MOF exhibits antioxidant capacity and promotes bone regeneration, making it a promising strategy for the treatment of periodontitis.

Non-canonical Wnt signaling promotes epithelial fluidization in the repairing airway

Concerted migration of basal stem cells (BCs) in the airway, also known as epithelial fluidization, has been implicated in epithelial repair after injury. How BC migration is regulated, and how it influences the success of epithelial repair, remains unclear. Here we have identified non-canonical Wnt signaling through Ptk7, Fzd7, and YAP as a critical regulator of BC migration in the mouse trachea. Using live imaging and genetic studies in the mouse, we find that Ptk7 is required for the concerted movement of BCs after injury, and that this requirement extends to BC proliferation and subsequent restoration of epithelial homeostasis after injury. We demonstrate that Ptk7 exerts this function in conjunction with Wnt5a and Fzd7, and through YAP activation in BCs. Our data provide mechanistic insight into the regulation of epithelial repair in the airway.

The Rho GEF Trio functions in contact inhibition of locomotion of neural crest cells by interacting with Ptk7

Neural crest (NC) cells are highly migratory cells that contribute to a wide range of vertebrate tissues and must respond to a variety of external signals to precisely control directed cell migration. The RhoGEF Trio is particularly well suited to relay signals to the cytoskeleton because it contains two GEF domains that activate Rac1 and RhoA, respectively. Previously, we have shown that Trio is dynamically localized in Xenopus NC cells and required for their migration. However, how its distinct enzymatic functions are spatially controlled remains unclear. Here, we show that Trio is required for contact inhibition of locomotion (CIL), a phenomenon whereby NC cells change their polarity and directionality upon cell-cell contact. At cell-cell contacts, Trio interacts with Ptk7, a regulator of planar cell polarity that we have recently shown to be required for CIL. Our data suggest that Ptk7 inhibits the Rac1 activity of Trio, thereby limiting Trio activity to the activation of RhoA and promoting CIL.

Transcriptomic Analysis of Muscle Satellite Cell Regulation on Intramuscular Preadipocyte Differentiation in Tan Sheep

Intramuscular fat (IMF) content is a key factor influencing meat properties including tenderness, flavor, and marbling. However, the complex molecular mechanisms regulating IMF deposition, especially the interactions between intramuscular preadipocytes (IMAdCs) and skeletal muscle satellite cells (SMSCs), remain unclear. In this study, a direct co-culture system of sheep IMAdCs and SMSCs was used to elucidate their intercellular interactions. RNA sequencing and bioinformatics analyses were performed under monoculture and co-culture conditions for later stages of differentiation. The obtained results showed that SMSCs significantly inhibited the adipogenic capacity of IMAdCs. This was reflected in the co-culture markedly altered gene expression and observations of lipid droplets in our studies, i.e., the PPARG, ACOX2, PIK3R1, FABP5, FYN, ALDOC, PFKM, PFKL, HADH, and HADHB genes were down-regulated in the co-cultured IMAdCs in association with the inhibition of fat deposition, whereas ACSL3, ACSL4, ATF3, EGR1, and IGF1R within the genes upregulated in co-culture IMAdCs were associated with the promotion of lipid metabolism. In addition, GO, KEGG, and ligand-receptor pairing analyses further elucidated the molecular mechanisms of intercellular communication. These findings emphasize the regulatory role of SMSCs on intramuscular preadipocyte differentiation and lipid metabolism, providing a theoretical framework for targeted molecular strategies to improve sheep meat quality.

Anti-PTK7 Monoclonal Antibodies Suppresses Oncogenic Phenotypes in Cellular and Xenograft Models of Triple-Negative Breast Cancer

Protein tyrosine kinase 7 (PTK7), a catalytically defective receptor protein tyrosine kinase, is frequently upregulated in various cancers, including triple-negative breast cancer (TNBC), and is associated with poor clinical outcomes. Analysis of The Cancer Genome Atlas (TCGA) data confirmed that PTK7 mRNA expression is significantly higher in TNBC tumor tissues compared with adjacent normal tissues and non-TNBC breast cancer subtypes. Kaplan-Meier survival analysis demonstrated a strong correlation between high PTK7 expression and worse relapse-free survival in TNBC patients (HR = 1.46, p = 0.015). In vitro, anti-PTK7 monoclonal antibodies (mAbs) significantly reduced proliferation, wound healing, migration, and invasion in TNBC MDA-MB-231 cells. Ki-67 immunofluorescence assays revealed substantial decreases in cell proliferation following treatment with PTK7 mAbs (32-m, 43-m, 50-m, and 52-m). Moreover, actin polymerization, a critical process in cell migration and invasion, was markedly impaired upon PTK7 mAb treatment. In vivo, PTK7 mAbs significantly reduced tumor volume and weight in a TNBC xenograft mouse model compared with controls. Treated tumors exhibited decreased expression of Ki-67 and vimentin, indicating reduced proliferation and epithelial-to-mesenchymal transition. These findings highlight PTK7 as a promising therapeutic target in TNBC and demonstrate the potent anti-cancer effects of PTK7-neutralizing mAbs both in vitro and in vivo. Further exploration of PTK7-targeted therapies, including humanized mAbs and antibody-drug conjugates, is warranted to advance treatment strategies for PTK7-positive TNBC.

An overview of Sgc8 aptamer as a potential theranostic agent for cancer with PTK7 oncogenic target

Aptamers have attracted exceptional attention in medical field due to their intrinsic properties equivalent to antibodies such as high target affinity, low immunogenicity and toxicity, cost-effectiveness and ease of synthesis and modification, and good stability under extreme conditions, thereby providing new avenues for basic research and clinical application. Protein tyrosine kinase 7 (PTK7) has been proved to be closely linked with the progression of many types of cancer. The aberrant expression of PTK7 has positioned it as a potential theranostic biomarker for multiple cancers. Aptamer sgc8 was initially identified for its high-affinity binding to PTK7 on the T-cell acute lymphoblastic leukemia cell line (CCRF-CEM) through cell-SELEX (systematic evolution of ligands by exponential enrichment) and subsequently has demonstrated the ability to effectively recognize many types of cancer cells that express PTK7 oncogenic target. The easily modifiable nature of sgc8 facilitates its conjugation with functional agents and drugs. This identification mode and modification approach of aptamers against cancer cells provides a potential strategy for cancer diagnosis and treatment. In this review, we discuss the potential of sgc8 aptamers in early cancer diagnosis and targeted therapy, focusing specifically on their interaction with the oncogenic biomarker PTK7.

Promising therapeutic targets for tumor treatment: Cleaved activation of receptors in the nucleus

A new fate of cell surface receptors, cleaved activation in the nucleus, is summarized. The intracellular domain (ICD) of cell surface receptors, cleaved by enzymes like γ-secretase, translocates to the nucleus to form transcriptional complexes participating in the onset and development of tumors. The fate is clinically significant, as inhibitors of cleavage enzymes have shown effectiveness in treating advanced tumors by reducing tumorigenic ICDs. Additionally, the construction of synthetic receptors also conforms with the fate mechanism. This review details each step of cleaved activation in the nucleus, elucidates tumorigenic mechanisms, explores application in antitumor therapy, and scrutinizes possible limitations.

Therapeutic targeting of the protein tyrosine kinase-7 in cancer: an overview

The protein tyrosine kinase-7 (PTK7) is an evolutionarily conserved transmembrane receptor that has emerged as a potential therapeutic target for human tumors. PTK7 is a pseudokinase that is involved in the modulation of the Wnt signaling pathway through interactions with other receptors. These interactions result in targeted gene activation that regulates cell polarity, migration, and proliferation during embryogenesis. Aside of this role during development, PTK7 has been shown as overexpressed in numerous cancers including colon carcinoma, leukemia, neuroblastoma, hepatoma, and ovarian cancer. The activity of PTK7 and the direct correlation with poor prognosis have fostered preclinical investigations and phase I clinical trials, aiming at inhibiting PTK7 and inducing antitumoral effects. In this review, we provide an exhaustive overview of the diverse approaches that use PTK7 as a new molecular target for cancer therapy in different tumor types. We discuss current therapies and future strategies including chimeric antigen receptor-T cells, antibody-drug conjugates, aptamers, based on up-to-date literature and ongoing research progress.

Non-canonical Wnt signaling triggered by WNT2B drives adrenal aldosterone production

The steroid hormone aldosterone, produced by the zona glomerulosa (zG) of the adrenal gland, is a master regulator of plasma electrolytes and blood pressure. While aldosterone control by the renin-angiotensin system is well understood, other key regulatory factors have remained elusive. Here, we replicated a prior association between a non-coding variant in WNT2B and an increased risk of primary aldosteronism, a prevalent and debilitating disease caused by excessive aldosterone production. We further show that in both mice and humans, WNT2B is expressed in the mesenchymal capsule surrounding the adrenal cortex, in close proximity to the zG. Global loss of Wnt2b in the mouse results in a dysmorphic and hypocellular zG, with impaired aldosterone production. Similarly, humans harboring WNT2B loss-of-function mutations develop a novel form of Familial Hyperreninemic Hypoaldosteronism, designated here as Type 4. Additionally, we demonstrate that WNT2B signals by activating the non-canonical Wnt/planar cell polarity pathway. Our findings identify WNT2B as a key regulator of zG function and aldosterone production with important clinical implications.

Progress in the development of modulators targeting Frizzleds

The Frizzleds (FZDs) receptors on the cell surface belong to the class F of G protein-coupled receptors (GPCRs) which are the major receptors of WNT protein that mediates the classical WNT signaling pathway and other non-classical pathways. Besides, the FZDs also play a core role in tissue regeneration and tumor occurrence. With the structure and mechanism of FZDs activation becoming clearer, a series of FZDs modulators (inhibitors and agonists) have been developed, with the hope of bringing benefits to the treatment of cancer and degenerative diseases. Most of the FZDs inhibitors (small molecules, antibodies or designed protein inhibitors) block WNT signaling through binding to the cysteine-rich domain (CRD) of FZDs. Several small molecules impede FZDs activation by targeting to the third intracellular domain or the transmembrane domain of FZDs. However, three small molecules (FZM1.8, SAG1.3 and purmorphamine) activate the FZDs through direct interaction with the transmembrane domain. Another type of FZDs agonists are bivalent or tetravalent antibodies which activate the WNT signaling via inducing FZD-LRP5/6 heterodimerization. In this article, we reviewed the FZDs modulators reported in recent years, summarized the critical molecules' discovery processes and the elucidated relevant structural and pharmacological mechanisms. We believe the summaried molecular mechanisms of the relevant modulators could provide important guidance and reference for the future development of FZD modulators.

Intraglandular dissemination: a special pathological feature

Intraglandular dissemination is an important pathological feature of thyroid cancer, yet the biological characteristics of this phenomenon remain relatively underexplored. This paper aims to provide a comprehensive overview of its biological behaviors, protein expressions, and identification methods. Several retrospective studies have found that thyroid cancers with intraglandular dissemination have higher rates of lymph node metastasis, capsule invasion, and vascular invasion, exhibiting more aggressive biological behavior. Immunohistochemistry results show abnormal expression of proteins such as FKBP5, CENPF, CX26, KIF11, PTK7, which are associated with poor prognosis in thyroid cancers with intraglandular dissemination, offering potential guidance for specific targeted therapy in the future. Moreover, adjunctive techniques including ultrasound, fine-needle aspiration, and genetic testing offer valuable support in accurately identifying these cases, facilitating moreproactive treatment and closer follow-up.

Why Is Wnt/β-Catenin Not Yet Targeted in Routine Cancer Care?

Despite significant progress in cancer prevention, screening, and treatment, the still limited number of therapeutic options is an obstacle towards increasing the cancer cure rate. In recent years, many efforts were put forth to develop therapeutics that selectively target different components of the oncogenic Wnt/β-catenin signaling pathway. These include small molecule inhibitors, antibodies, and more recently, gene-based approaches. Although some of them showed promising outcomes in clinical trials, the Wnt/β-catenin pathway is still not targeted in routine clinical practice for cancer management. As for most anticancer treatments, a critical limitation to the use of Wnt/β-catenin inhibitors is their therapeutic index, i.e., the difficulty of combining effective anticancer activity with acceptable toxicity. Protecting healthy tissues from the effects of Wnt/β-catenin inhibitors is a major issue due to the vital role of the Wnt/β-catenin signaling pathway in adult tissue homeostasis and regeneration. In this review, we provide an up-to-date summary of clinical trials on Wnt/β-catenin pathway inhibitors, examine their anti-tumor activity and associated adverse events, and explore strategies under development to improve the benefit/risk profile of this therapeutic approach.

Wnt/β-catenin signaling components and mechanisms in bone formation, homeostasis, and disease

Wnts are secreted, lipid-modified proteins that bind to different receptors on the cell surface to activate canonical or non-canonical Wnt signaling pathways, which control various biological processes throughout embryonic development and adult life. Aberrant Wnt signaling pathway underlies a wide range of human disease pathogeneses. In this review, we provide an update of Wnt/β-catenin signaling components and mechanisms in bone formation, homeostasis, and diseases. The Wnt proteins, receptors, activators, inhibitors, and the crosstalk of Wnt signaling pathways with other signaling pathways are summarized and discussed. We mainly review Wnt signaling functions in bone formation, homeostasis, and related diseases, and summarize mouse models carrying genetic modifications of Wnt signaling components. Moreover, the therapeutic strategies for treating bone diseases by targeting Wnt signaling, including the extracellular molecules, cytosol components, and nuclear components of Wnt signaling are reviewed. In summary, this paper reviews our current understanding of the mechanisms by which Wnt signaling regulates bone formation, homeostasis, and the efforts targeting Wnt signaling for treating bone diseases. Finally, the paper evaluates the important questions in Wnt signaling to be further explored based on the progress of new biological analytical technologies.

Identification of the Binding Site between Aptamer sgc8c and PTK7

Aptamers are single-stranded RNA or DNA molecules that can specifically bind to targets and have found broad applications in cancer early-stage detection, accurate drug delivery, and precise treatment. Although various aptamer screening methods have been developed over the past several decades, the accurate binding site between the target and the aptamer cannot be characterized during a typical aptamer screening process. In this research, we chose a widely used aptamer screened by our group, sgc8c, and its target protein tyrosine kinase 7 (PTK7) as the model aptamer and target and tried to determine the binding site between aptamer sgc8c and PTK7. Through sequential protein truncation, we confirmed that the exact binding site of sgc8c was within the region of Ig 3 to Ig 4 in the extracellular domain of PTK7. Using in vitro expressed Ig (3-4), we successfully acquired the crystal of an sgc8c-Ig (3-4) binding complex. The possible sgc8c-binding amino acid residues on PTK7 and PTK7-binding nucleotide residues on sgc8c were further identified and simulated by mass spectrometry and molecular dynamics simulation and finally verified by aptamer/protein truncation and mutation.

Recent insights into the therapeutic strategies targeting the pseudokinase PTK7 in cancer

The generation of drugs counteracting deregulated protein kinases has been a major focus in cancer therapy development. Breakthroughs in this effort have produced many therapeutic agents to the benefit of patients, mostly through the development of chemical or antibody-based drugs targeting active kinases. These strategies are challenged when considering catalytically inactive protein kinases (or pseudokinases), which represent 10% of the human kinome with many of relevance in cancer. Among the so-called pseudotyrosine kinases, the PTK7 receptor tyrosine kinase (RTK) stands as a bona fide target overexpressed in several solid tumors and hematological malignancies and linked to metastasis, poor prognosis, and resistance to treatment. Despite the lack of catalytic activity, PTK7 has signaling capacities through heterodimerization with active RTKs and offers pharmacological targeting opportunities through its inactive kinase domain. Moreover, PTK7-targeting strategies based on antibody-drug conjugates, aptamers, and CAR-T cell-based therapies have demonstrated encouraging results in preclinical and clinical settings. We review the most recent data assigning to PTK7 a prominent role in cancer progression as well as current preclinical and clinical targeting strategies against RTK family pseudokinases including PTK7.

Vangl-dependent mesenchymal thinning shapes the distal lung during murine sacculation

The planar cell polarity (PCP) complex is speculated to function in murine lung development, where branching morphogenesis generates an epithelial tree whose distal tips expand dramatically during sacculation. Here, we show that PCP is dispensable in the airway epithelium for sacculation. Rather, we find a Celsr1-independent role for the PCP component Vangl in the pulmonary mesenchyme: loss of Vangl1/2 inhibits mesenchymal thinning and expansion of the saccular epithelium. Further, loss of mesenchymal Wnt5a mimics sacculation defects observed in Vangl2-mutant lungs, implicating mesenchymal Wnt5a/Vangl signaling as a key regulator of late lung morphogenesis. A computational model predicts that sacculation requires a fluid mesenchymal compartment. Lineage-tracing and cell-shape analyses are consistent with the mesenchyme acting as a fluid tissue, suggesting that loss of Vangl1/2 impacts the ability of mesenchymal cells to exchange neighbors. Our data thus identify an explicit function for Vangl and the pulmonary mesenchyme in actively shaping the saccular epithelium.

Systematic dissection of tumor-normal single-cell ecosystems across a thousand tumors of 30 cancer types

The complexity of the tumor microenvironment poses significant challenges in cancer therapy. Here, to comprehensively investigate the tumor-normal ecosystems, we perform an integrative analysis of 4.9 million single-cell transcriptomes from 1070 tumor and 493 normal samples in combination with pan-cancer 137 spatial transcriptomics, 8887 TCGA, and 1261 checkpoint inhibitor-treated bulk tumors. We define a myriad of cell states constituting the tumor-normal ecosystems and also identify hallmark gene signatures across different cell types and organs. Our atlas characterizes distinctions between inflammatory fibroblasts marked by AKR1C1 or WNT5A in terms of cellular interactions and spatial co-localization patterns. Co-occurrence analysis reveals interferon-enriched community states including tertiary lymphoid structure (TLS) components, which exhibit differential rewiring between tumor, adjacent normal, and healthy normal tissues. The favorable response of interferon-enriched community states to immunotherapy is validated using immunotherapy-treated cancers (n = 1261) including our lung cancer cohort (n = 497). Deconvolution of spatial transcriptomes discriminates TLS-enriched from non-enriched cell types among immunotherapy-favorable components. Our systematic dissection of tumor-normal ecosystems provides a deeper understanding of inter- and intra-tumoral heterogeneity.

Elucidating the Functional Mechanism of PTK7 in Cancer Development through Spatial Assembly Analysis Using Super Resolution Imaging

Protein tyrosine kinase-7 (PTK7) has been reported as a vital participant in the Wnt signaling pathway, influencing tumorigenesis and metastasis. However, their specific roles in the mechanisms underlying cancer development and progression remain elusive. Here, using direct stochastic optical reconstruction microscopy (dSTORM) with aptamer-probe labeling, we first revealed that a weakening clustering distribution of PTK7 on the basal membranes happened as cellular migration increased during cancer progression. This correspondence was further supported by a diminished aggregated state of PTK7 caused by direct enhancement of cell migration. By comparing the alterations in PTK7 distribution with activation or inhibition of specific Wnt signaling pathway, we speculated that PTK7 could modulate cell migration by participating in the interplay between canonical Wnt (in MCF7 cells) and noncanonical Wnt signals (in MDA-MB-231 cells). Furthermore, we discovered that the spatial distribution morphology of PTK7 was also subject to the hydrolysis ability and activation state of the related hydrolase Matrix metallopeptidase14 (MMP14). This function-related specific assembly of PTK7 reveals a clear relationship between PTK7 and cancer. Meanwhile, potential molecular interactions predicted by the apparent assembly morphology can promote a deep understanding of the functional mechanism of PTK7 in cancer progress.

The Wnt Co-Receptor PTK7/Otk and Its Homolog Otk-2 in Neurogenesis and Patterning

Wnt signaling is a highly conserved metazoan pathway that plays a crucial role in cell fate determination and morphogenesis during development. Wnt ligands can induce disparate cellular responses. The exact mechanism behind these different outcomes is not fully understood but may be due to interactions with different receptors on the cell membrane. PTK7/Otk is a transmembrane receptor that is implicated in various developmental and physiological processes including cell polarity, cell migration, and invasion. Here, we examine two roles of Otk-1 and Otk-2 in patterning and neurogenesis. We find that Otk-1 is a positive regulator of signaling and Otk-2 functions as its inhibitor. We propose that PTK7/Otk functions in signaling, cell migration, and polarity contributing to the diversity of cellular responses seen in Wnt-mediated processes.

Knockdown of PTK7 Reduces the Oncogenic Potential of Breast Cancer Cells by Impeding Receptor Tyrosine Kinase Signaling

Protein tyrosine kinase 7 (PTK7), a catalytically defective receptor tyrosine kinase (RTK), is often upregulated in various cancers. This study aimed to validate PTK7 as a target for breast cancer (BC) and investigate its oncogenic signaling mechanism. BC tissue analysis showed significantly elevated PTK7 mRNA levels, especially in refractory triple-negative breast cancer (TNBC) tissues, compared with normal controls. Similarly, BC cell lines exhibited increased PTK7 expression. Knockdown of PTK7 inhibited the proliferation of T-47D and MCF-7 hormone-receptor-positive BC cell-lines and of HCC1187, MDA-MB-231, MDA-MB-436, and MDA-MB-453 TNBC cells. PTK7 knockdown also inhibited the adhesion, migration, and invasion of MDA-MB-231, MDA-MB-436, and MDA-MB-453 cells, and reduced the phosphorylation levels of crucial oncogenic regulators including extracellular signal-regulated kinase (ERK), Akt, and focal adhesion kinase (FAK). Furthermore, PTK7 interacts with fibroblast growth factor receptor 1 (FGFR1) and epidermal growth factor receptor (EGFR) expressed in MDA-MB-231 cells. Knockdown of PTK7 decreased the growth-factor-induced phosphorylation of FGFR1 and EGFR in MDA-MB-231 cells, indicating its association with RTK activation. In conclusion, PTK7 plays a significant role in oncogenic signal transduction by enhancing FGFR1 and EGFR activation, influencing BC tumorigenesis and metastasis. Hence, PTK7 represents a potential candidate for targeted BC therapy, including TNBC.

Non-canonical Wnt signaling in the eye

Wnt signaling comprises a group of complex signal transduction pathways that play critical roles in cell proliferation, differentiation, and apoptosis during development, as well as in stem cell maintenance and adult tissue homeostasis. Wnt pathways are classified into two major groups, canonical (β-catenin-dependent) or non-canonical (β-catenin-independent). Most previous studies in the eye have focused on canonical Wnt signaling, and the role of non-canonical signaling remains poorly understood. Additionally, the crosstalk between canonical and non-canonical Wnt signaling in the eye has hardly been explored. In this review, we present an overview of available data on ocular non-canonical Wnt signaling, including developmental and functional aspects in different eye compartments. We also discuss important changes of this signaling in various ocular conditions, such as keratoconus, aniridia-related keratopathy, diabetes, age-related macular degeneration, optic nerve damage, pathological angiogenesis, and abnormalities in the trabecular meshwork and conjunctival cells, and limbal stem cell deficiency.

Advances in chimeric antigen receptor T cells therapy in the treatment of breast cancer

Breast cancer (BC) is the most frequently occurring cancer type seriously threatening the lives of women worldwide. Clinically, the high frequency of diverse resistance to current therapeutic strategies advocates a demand to develop novel and effective approaches for the efficient treatment of BC. The chimeric antigen receptor T (CAR-T) cells therapy, one of the immunotherapies, has displayed powerful capacity to specifically kill and eliminate tumors. Due to the success of CAR-T therapy achieved in treating hematological malignancy, the effect of CAR-T cells therapy has been tested in various human diseases including breast cancer. This review summarized and discussed the landscape of the CAR-T therapy for breast cancer, including the advances, challenge and countermeasure of CAR-T therapy in research and clinical application. The roles of potential antigen targets, tumor microenvironment, immune escape in regulating CAR-T therapy, the combination of CAR-T therapy with other therapeutic strategies to further enhance therapeutic efficacy of CAR-T treatment were also highlighted. Therefore, our review provided a comprehensive understanding of CAR-T cell therapy in breast cancer which will awake huge interests for future in-depth investigation of CAR-T based therapy in cancer treatment.

Senescent cells perturb intestinal stem cell differentiation through Ptk7 induced noncanonical Wnt and YAP signaling

Cellular senescence and the senescence-associated secretory phenotype (SASP) are implicated in aging and age-related disease, and SASP-related inflammation is thought to contribute to tissue dysfunction in aging and diseased animals. However, whether and how SASP factors influence the regenerative capacity of tissues remains unclear. Here, using intestinal organoids as a model of tissue regeneration, we show that SASP factors released by senescent fibroblasts deregulate stem cell activity and differentiation and ultimately impair crypt formation. We identify the secreted N-terminal domain of Ptk7 as a key component of the SASP that activates non-canonical Wnt / Ca2+ signaling through FZD7 in intestinal stem cells (ISCs). Changes in cytosolic [Ca2+] elicited by Ptk7 promote nuclear translocation of YAP and induce expression of YAP/TEAD target genes, impairing symmetry breaking and stem cell differentiation. Our study discovers secreted Ptk7 as a factor released by senescent cells and provides insight into the mechanism by which cellular senescence contributes to tissue dysfunction in aging and disease.

Wnt/planar cell polarity signaling controls morphogenetic movements of gastrulation and neural tube closure

Gastrulation and neurulation are successive morphogenetic processes that play key roles in shaping the basic embryonic body plan. Importantly, they operate through common cellular and molecular mechanisms to set up the three spatially organized germ layers and to close the neural tube. During gastrulation and neurulation, convergent extension movements driven by cell intercalation and oriented cell division generate major forces to narrow the germ layers along the mediolateral axis and elongate the embryo in the anteroposterior direction. Apical constriction also makes an important contribution to promote the formation of the blastopore and the bending of the neural plate. Planar cell polarity proteins are major regulators of asymmetric cell behaviors and critically involved in a wide variety of developmental processes, from gastrulation and neurulation to organogenesis. Mutations of planar cell polarity genes can lead to general defects in the morphogenesis of different organs and the co-existence of distinct congenital diseases, such as spina bifida, hearing deficits, kidney diseases, and limb elongation defects. This review outlines our current understanding of non-canonical Wnt signaling, commonly known as Wnt/planar cell polarity signaling, in regulating morphogenetic movements of gastrulation and neural tube closure during development and disease. It also attempts to identify unanswered questions that deserve further investigations.

Protein Tyrosine Kinase 7 (PTK7) Promotes Metastasis in Hepatocellular Carcinoma via SOX9 Regulation and TGF-β Signaling

BACKGROUND & AIMS

Metastasis is found in most advanced hepatocellular carcinoma (HCC) patients, and it drives tumor recurrence and systemic failure. There is no effective treatment owing to its complex biological features. Many of the molecular drivers of metastasis are crucial players in normal physiology but behave unconventionally during cancer progression. Targeting these molecular drivers for therapy and differentiating them from a physiological background require a detailed examination of the novel mechanisms involved in their activation during metastasis.

METHODS

Publicly available transcriptomic data such as that of TCGA-LIHC and Gene Expression Omnibus were utilized to identify novel targets upregulated in advanced and metastatic HCC. Validation of candidates was assisted by immunohistochemistry performed on tissue microarrays derived from more than 100 HCC patients. Expression of protein tyrosine kinase 7 (PTK7) was studied under the treatment of transforming growth factor-β1 and knockdown of SRY-Box Transcription Factor 9 (SOX9) to delineate upstream regulation, while CRISPR-mediated knockout and lentiviral overexpression of PTK7 in HCC cells were performed to study their functional and signaling consequences. Manipulated HCC cells were injected into mice models either by orthotopic or tail-vein injection to observe for any in vivo pro-metastatic effects.

RESULTS

PTK7 was discovered to be the kinase most significantly upregulated in advanced and metastatic HCC, at both transcriptomic and proteomic level. Bioinformatic analyses and functional assays performed in HCC cell lines revealed transforming growth factor-β signaling and SOX9 to be important activators of PTK7 expression. Functionally, enrichment of PTK7 expression could positively regulate metastatic potential of HCC cells in vitro and in lung metastasis models performed in immunodeficient mice. The up-regulation of PTK7 recruited the epithelial-mesenchymal transition components, zinc finger protein SNAI2 (SLUG) and zinc finger E-box-binding homeobox 1 (ZEB1).

CONCLUSIONS

Our study proposes PTK7 as a novel molecular driver in metastatic HCC, particularly in a transforming growth factor-β-activated microenvironment. The preferential expression of PTK7 resulted in a previously unobserved regulatory effect on the recruitment of epithelial-mesenchymal transition components, which established PTK7 as a potential determinant of specific epithelial-mesenchymal transition status. Therefore, our data support the continual development of PTK7-targeted agents as antimetastatic therapies.

Anti-PTK7 Monoclonal Antibodies Inhibit Angiogenesis by Suppressing PTK7 Function

Simple Summary

PTK7 is a catalytically defective receptor protein tyrosine kinase. We previously demonstrated that PTK7 enhances angiogenesis by interacting with KDR, a vascular endothelial growth factor (VEGF) receptor important for angiogenesis, and activating it through oligomerization. To control angiogenesis by inhibiting PTK7 function, we developed anti-PTK7 monoclonal antibodies (mAbs). The selected PTK7 mAbs reduced VEGF-induced angiogenic phenotypes of endothelial cells and angiogenesis ex vivo and in vivo. The PTK7 mAbs also inhibited VEGF-induced KDR activation in endothelial cells and its downstream signaling and PTK7–KDR interaction. Our results show that the PTK7 mAbs inhibit angiogenesis by blocking PTK7 function. Therefore, PTK7 mAbs could be applied as therapeutics to control angiogenesis-associated diseases such as metastatic cancers.

Abstract

PTK7, a catalytically defective receptor protein tyrosine kinase, promotes angiogenesis by activating KDR through direct interaction and induction of KDR oligomerization. This study developed anti-PTK7 monoclonal antibodies (mAbs) to regulate angiogenesis by inhibiting PTK7 function. The effect of anti-PTK7 mAbs on vascular endothelial growth factor (VEGF)-induced angiogenic phenotypes in human umbilical vascular endothelial cells (HUVECs) was examined. Analysis of mAb binding with PTK7 deletion mutants revealed that mAb-43 and mAb-52 recognize immunoglobulin (Ig) domain 2 of PTK7, whereas mAb-32 and mAb-50 recognize Ig domains 6–7. Anti-PTK7 mAbs inhibited VEGF-induced adhesion and wound healing in HUVECs. mAb-32, mAb-43, and mAb-52 dose-dependently mitigated VEGF-induced migration and invasion in HUVECs without exerting cytotoxic effects. Additionally, mAb-32, mAb-43, and mAb-52 inhibited capillary-like tube formation in HUVECs, and mAb-32 and mAb-43 suppressed angiogenesis ex vivo (aortic ring assay) and in vivo (Matrigel plug assay). Furthermore, mAb-32 and mAb-43 downregulated VEGF-induced KDR activation and downstream signaling and inhibited PTK7–KDR interaction in PTK7-overexpressing and KDR-overexpressing HEK293 cells. Thus, anti-PTK7 mAbs inhibit angiogenic phenotypes by blocking PTK7–KDR interaction. These findings indicate that anti-PTK7 mAbs that neutralize PTK7 function can alleviate impaired angiogenesis-associated pathological conditions, such as cancer metastasis.

Multiomics characterization implicates PTK7 in ovarian cancer EMT and cell plasticity and offers strategies for therapeutic intervention

Most patients with ovarian cancer (OC) are diagnosed at a late stage when there are very few therapeutic options and a poor prognosis. This is due to the lack of clearly defined underlying mechanisms or an oncogenic addiction that can be targeted pharmacologically, unlike other types of cancer. Here, we identified protein tyrosine kinase 7 (PTK7) as a potential new therapeutic target in OC following a multiomics approach using genetic and pharmacological interventions. We performed proteomics analyses upon PTK7 knockdown in OC cells and identified novel downstream effectors such as synuclein-γ (SNCG), SALL2, and PP1γ, and these findings were corroborated in ex vivo primary samples using PTK7 monoclonal antibody cofetuzumab. Our phosphoproteomics analyses demonstrated that PTK7 modulates cell adhesion and Rho-GTPase signaling to sustain epithelial-mesenchymal transition (EMT) and cell plasticity, which was confirmed by high-content image analysis of 3D models. Furthermore, using high-throughput drug sensitivity testing (525 drugs) we show that targeting PTK7 exhibited synergistic activity with chemotherapeutic agent paclitaxel, CHK1/2 inhibitor prexasertib, and PLK1 inhibitor GSK461364, among others, in OC cells and ex vivo primary samples. Taken together, our study provides unique insight into the function of PTK7, which helps to define its role in mediating aberrant Wnt signaling in ovarian cancer.

The Ror-Family Receptors in Development, Tissue Regeneration and Age-Related Disease

The Ror-family proteins, Ror1 and Ror2, act as receptors or co-receptors for Wnt5a and its related Wnt proteins to activate non-canonical Wnt signaling. Ror1 and/or Ror2-mediated signaling plays essential roles in regulating cell polarity, migration, proliferation and differentiation during developmental morphogenesis, tissue-/organo-genesis and regeneration of adult tissues following injury. Ror1 and Ror2 are expressed abundantly in developing tissues in an overlapping, yet distinct manner, and their expression in adult tissues is restricted to specific cell types such as tissue stem/progenitor cells. Expression levels of Ror1 and/or Ror2 in the adult tissues are increased following injury, thereby promoting regeneration or repair of these injured tissues. On the other hand, disruption of Wnt5a-Ror2 signaling is implicated in senescence of tissue stem/progenitor cells that is related to the impaired regeneration capacity of aged tissues. In fact, Ror1 and Ror2 are implicated in age-related diseases, including tissue fibrosis, atherosclerosis (or arteriosclerosis), neurodegenerative diseases, and cancers. In these diseases, enhanced and/or sustained (chronic) expression of Ror1 and/or Ror2 is observed, and they might contribute to the progression of these diseases through Wnt5a-dependent and -independent manners. In this article, we overview recent advances in our understanding of the roles of Ror1 and Ror2-mediated signaling in the development, tissue regeneration and age-related diseases, and discuss their potential to be therapeutic targets for chronic inflammatory diseases and cancers.

PTK7, a Catalytically Inactive Receptor Tyrosine Kinase, Increases Oncogenic Phenotypes in Xenograft Tumors of Esophageal Squamous Cell Carcinoma KYSE-30 Cells

Protein tyrosine kinase 7 (PTK7), a catalytically defective receptor protein tyrosine kinase, is upregulated in tumor tissues and cell lines of esophageal squamous cell carcinoma (ESCC). We showed that PTK7 plays an oncogenic role in various ESCC cell lines. However, its role as an oncogene has not been demonstrated in vivo. Here, we examined the influence of PTK7 on the tumorigenic potential of ESCC KYSE-30 cells, which are known to establish xenograft tumors. Overexpression of PTK7 enhanced the proliferation, adhesion, wound healing, and migration of KYSE-30 cells, and these effects were reversed by the knockdown of PTK7. PTK7 overexpression and knockdown, respectively, increased and decreased the tyrosine phosphorylation of cellular proteins and the phosphorylation of ERK, AKT, and FAK, which are important for cell proliferation, survival, adhesion, and migration. Additionally, PTK7 overexpression and silencing, respectively, increased and decreased the weight, volume, and number of Ki-67-positive proliferating cells in xenograft tumors of KYSE-30 cells. Therefore, we propose that PTK7 plays an important role in the tumorigenesis of ESCC cells in vivo and is a potential therapeutic target for ESCC.

Whole-Exome Sequencing Identifies a Novel Germline Variant in PTK7 Gene in Familial Colorectal Cancer

Colorectal cancer (CRC) is the third most frequently diagnosed malignancy worldwide. Only 5% of all CRC cases are due to germline mutations in known predisposition genes, and the remaining genetic burden still has to be discovered. In this study, we performed whole-exome sequencing on six members of a Polish family diagnosed with CRC and identified a novel germline variant in the protein tyrosine kinase 7 (inactive) gene (PTK7, ENST00000230419, V354M). Targeted screening of the variant in 1705 familial CRC cases and 1674 healthy elderly individuals identified the variant in an additional familial CRC case. Introduction of this variant in HT-29 cells resulted in increased cell proliferation, migration, and invasion; it also caused down-regulation of CREB, p21 and p53 mRNA and protein levels, and increased AKT phosphorylation. These changes indicated inhibition of apoptosis pathways and activation of AKT signaling. Our study confirmed the oncogenic function of PTK7 and supported its role in genetic predisposition of familial CRC.

The scaffolding protein flot2 promotes cytoneme-based transport of wnt3 in gastric cancer

The Wnt/β-catenin signalling pathway regulates multiple cellular processes during development and many diseases, including cell proliferation, migration, and differentiation. Despite their hydrophobic nature, Wnt proteins exert their function over long distances to induce paracrine signalling. Recent studies have identified several factors involved in Wnt secretion; however, our understanding of how Wnt ligands are transported between cells to interact with their cognate receptors is still debated. Here, we demonstrate that gastric cancer cells utilise cytonemes to transport Wnt3 intercellularly to promote proliferation and cell survival. Furthermore, we identify the membrane-bound scaffolding protein Flotillin-2 (Flot2), frequently overexpressed in gastric cancer, as a modulator of these cytonemes. Together with the Wnt co-receptor and cytoneme initiator Ror2, Flot2 determines the number and length of Wnt3 cytonemes in gastric cancer. Finally, we show that Flotillins are also necessary for Wnt8a cytonemes during zebrafish embryogenesis, suggesting a conserved mechanism for Flotillin-mediated Wnt transport on cytonemes in development and disease.

WNT11/ROR2 signaling is associated with tumor invasion and poor survival in breast cancer

BACKGROUND

Breast cancer has been associated with activation of the WNT signaling pathway, although no driver mutations in WNT genes have been found yet. Instead, a high expression of the alternative WNT receptor ROR2 was observed, in particular in breast cancer brain metastases. However, its respective ligand and downstream signaling in this context remained unknown.

METHODS

We modulated the expression of ROR2 in human breast cancer cells and characterized their gene and protein expression by RNA-Seq, qRT-PCR, immunoblots and reverse phase protein array (RPPA) combined with network analyses to understand the molecular basis of ROR2 signaling in breast cancer. Using co-immunoprecipitations, we verified the interaction of ROR2 with the identified ligand, WNT11. The functional consequences of WNT11/ROR2 signaling for tumor cell aggressiveness were assessed by microscopy, impedance sensing as well as viability and invasion assays. To evaluate the translational significance of our findings, we performed gene set enrichment, expression and survival analyses on human breast cancer brain metastases.

RESULTS

We found ROR2 to be highly expressed in aggressive breast tumors and associated with worse metastasis-free survival. ROR2 overexpression induced a BRCAness-like phenotype in a cell-context specific manner and rendered cells resistant to PARP inhibition. High levels of ROR2 were furthermore associated with defects in cell morphology and cell-cell-contacts leading to increased tumor invasiveness. On a molecular level, ROR2 overexpression upregulated several non-canonical WNT ligands, in particular WNT11. Co-immunoprecipitation confirmed that WNT11 indeed interacts with the cysteine-rich domain of ROR2 and triggers its invasion-promoting signaling via RHO/ROCK. Knockdown of WNT11 reversed the pro-invasive phenotype and the cellular changes in ROR2-overexpressing cells.

CONCLUSIONS

Taken together, our study revealed a novel auto-stimulatory loop in which ROR2 triggers the expression of its own ligand, WNT11, resulting in enhanced tumor invasion associated with breast cancer metastasis.

Local Wnt signalling in the asymmetric migrating vertebrate cells

Wnt signalling is known to generate cellular asymmetry via Wnt/planar cell polarity pathway (Wnt/PCP). Wnt/PCP acts locally (i) to orient membrane polarity and asymmetric establishment of intercellular junctions via conserved set of PCP proteins most specifically represented by Vangl and Prickle, and (ii) to asymmetrically rearrange cytoskeletal structures via downstream effectors of Dishevelled (Dvl). This process is best described on stable phenotypes of epithelial cells. Here, however, we review the activity of Wnt signalling in migratory cells which experience the extensive rearrangements of cytoskeleton and consequently dynamic asymmetry, making the localised effects of Wnt signalling easier to distinguish. Firstly, we focused on migration of neuronal axons, which allows to study how the pre-existent cellular asymmetry can influence Wnt signalling outcome. Then, we reviewed the role of Wnt signalling in models of mesenchymal migration including neural crest, melanoma, and breast cancer cells. Last, we collected evidence for local Wnt signalling in amoeboid cells, especially lymphocytes. As the outcome of this review, we identify blank spots in our current understanding of this topic, propose models that synthesise the current observations and allow formulation of testable hypotheses for the future research.

Non-canonical Wnt signaling promotes directed migration of intestinal stem cells to sites of injury

Tissue regeneration after injury requires coordinated regulation of stem cell activation, division, and daughter cell differentiation, processes that are increasingly well understood in many regenerating tissues. How accurate stem cell positioning and localized integration of new cells into the damaged epithelium are achieved, however, remains unclear. Here, we show that enteroendocrine cells coordinate stem cell migration towards a wound in the Drosophila intestinal epithelium. In response to injury, enteroendocrine cells release the N-terminal domain of the PTK7 orthologue, Otk, which activates non-canonical Wnt signaling in intestinal stem cells, promoting actin-based protrusion formation and stem cell migration towards a wound. We find that this migratory behavior is closely linked to proliferation, and that it is required for efficient tissue repair during injury. Our findings highlight the role of non-canonical Wnt signaling in regeneration of the intestinal epithelium, and identify enteroendocrine cell-released ligands as critical coordinators of intestinal stem cell migration.

The Mutational Landscape of PTK7 in Congenital Scoliosis and Adolescent Idiopathic Scoliosis

Depletion of ptk7 is associated with both congenital scoliosis (CS) and adolescent idiopathic scoliosis (AIS) in zebrafish models. However, only one human variant of PTK7 has been reported previously in a patient with AIS. In this study, we systemically investigated the variant landscape of PTK7 in 583 patients with CS and 302 patients with AIS from the Deciphering Disorders Involving Scoliosis and COmorbidities (DISCO) study. We identified a total of four rare variants in CS and four variants in AIS, including one protein truncating variant (c.464_465delAC) in a patient with CS. We then explored the effects of these variants on protein expression and sub-cellular location. We confirmed that the c.464_465delAC variant causes loss-of-function (LoF) of PTK7. In addition, the c.353C>T and c.2290G>A variants identified in two patients with AIS led to reduced protein expression of PTK7 as compared to that of the wild type. In conclusion, LoF and hypomorphic variants are associated with CS and AIS, respectively.

WNT5B in cellular signaling pathways

The Wnt signaling ligand WNT5B is implicated in various developmental pathways, both in normal and pathological physiology. Most of the research on WNT5B has been associated with expression analysis and disease states, leaving the signaling pathways underexplored. Here, we review the current understandings of WNT5B's regulation of signal transduction, from receptors to downstream mediators and transcription factors. We also describe its roles in β-catenin-dependent and β-catenin-independent (Planar Cell Polarity and Wnt/Ca²⁺) Wnt signaling.

Epigenetic Regulation of the Wnt/β-Catenin Signaling Pathway in Cancer

Studies over the past four decades have elucidated the role of Wnt/β-catenin mediated regulation in cell proliferation, differentiation and migration. These processes are fundamental to embryonic development, regeneration potential of tissues, as well as cancer initiation and progression. In this review, we focus on the epigenetic players which influence the Wnt/β-catenin pathway via modulation of its components and coordinated regulation of the Wnt target genes. The role played by crosstalk with other signaling pathways mediating tumorigenesis is also elaborated. The Hippo/YAP pathway is particularly emphasized due to its extensive crosstalk via the Wnt destruction complex. Further, we highlight the recent advances in developing potential therapeutic interventions targeting the epigenetic machinery based on the characterization of these regulatory networks for effective treatment of various cancers and also for regenerative therapies.

PTK7-Targeting CAR T-Cells for the Treatment of Lung Cancer and Other Malignancies

In spite of impressive success in treating hematologic malignancies, adoptive therapy with chimeric antigen receptor modified T cells (CAR T) has not yet been effective in solid tumors, where identification of suitable tumor-specific antigens remains a major obstacle for CAR T-cell therapy due to the “on target off tumor” toxicity. Protein tyrosine kinase 7 (PTK7) is a member of the Wnt-related pseudokinases and identified as a highly expressed antigen enriched in cancer stem cells (CSCs) from multiple solid tumors, including but not limited to triple-negative breast cancer, non-small-cell lung cancer, and ovarian cancer, suggesting it may serve as a promising tumor-specific target for CAR T-cell therapy. In this study, we constructed three different PTK7-specific CAR (PTK7-CAR1/2/3), each comprising a humanized PTK7-specific single-chain variable fragment (scFv), hinge and transmembrane (TM) regions of the human CD8α molecule, 4-1BB intracellular co-stimulatory domain (BB-ICD), and CD3ζ intracellular domain (CD3ζ-ICD) sequence, and then prepared the CAR T cells by lentivirus-mediated transduction of human activated T cells accordingly, and we sequentially evaluated their antigen-specific recognition and killing activity in vitro and in vivo. T cells transduced with all three PTK7-CAR candidates exhibited antigen-specific cytokine production and potent cytotoxicity against naturally expressing PTK7-positive tumor cells of multiple cancer types without mediating cytotoxicity of a panel of normal primary human cells; meanwhile, in vitro recursive cytotoxicity assays demonstrated that only PTK7-CAR2 modified T cells retained effective through multiple rounds of tumor challenge. Using in vivo xenograft models of lung cancers with different expression levels of PTK7, systemic delivery of PTK7-CAR2 modified T cells significantly prevented tumor growth and prolonged overall survival of mice. Altogether, our results support PTK7 as a therapeutic target suitable for CAR T-cell therapy that could be applied for lung cancers and many other solid cancers with PTK7 overexpression.

Ptk7 Is Dynamically Localized at Neural Crest Cell-Cell Contact Sites and Functions in Contact Inhibition of Locomotion

Neural crest (NC) cells are highly migratory cells that contribute to various vertebrate tissues, and whose migratory behaviors resemble cancer cell migration and invasion. Information exchange via dynamic NC cell-cell contact is one mechanism by which the directionality of migrating NC cells is controlled. One transmembrane protein that is most likely involved in this process is protein tyrosine kinase 7 (PTK7), an evolutionary conserved Wnt co-receptor that is expressed in cranial NC cells and several tumor cells. In Xenopus, Ptk7 is required for NC migration. In this study, we show that the Ptk7 protein is dynamically localized at cell-cell contact zones of migrating Xenopus NC cells and required for contact inhibition of locomotion (CIL). Using deletion constructs of Ptk7, we determined that the extracellular immunoglobulin domains of Ptk7 are important for its transient accumulation and that they mediate homophilic binding. Conversely, we found that ectopic expression of Ptk7 in non-NC cells was able to prevent NC cell invasion. However, deletion of the extracellular domains of Ptk7 abolished this effect. Thus, Ptk7 is sufficient at protecting non-NC tissue from NC cell invasion, suggesting a common role of PTK7 in contact inhibition, cell invasion, and tissue integrity.

Recent updates on Wnt signaling modulators: a patent review (2014-2020)

Introduction: Wnt signaling is a signal transduction pathway that plays a vital role in embryonic development and normal tissue preservation. Dysfunction of it gives rise to various diseases like cancer, Alzheimer's, metabolic and skeletal disorders, kidney and liver disease, etc. Thus, targeting Wnt pathway can be a potential approach to design and develop novel therapeutic classes.Areas covered: Authors provided an overview of Wnt modulators from 2014 to 2020. Different heterocyclic scaffolds and their pharmacology from a total of 104 PCT applications have been summarized.Expert opinion: The scientific community is working extensively to bring first in the class molecule to the market which targets Wnt pathway. Lorecivivint, Wnt inhibitor, for the treatment of knee Osteoarthritis and SM-04554, Wnt activator, for the treatment of androgenetic alopecia are currently under Phase III. Other molecules, LGK-974, RXC-004, ETC-159, CGX-1321, PRI-724, CWP-232291 and BC-2059 are also under different stages of clinical development for the treatment of cancer. Antibody based Wnt modulator, OTSA101-DTPA-90Y is currently under Phase I for the treatment of Relapsed or Refractory Synovial Sarcoma while OMP-18R5 is under Phase I for Metastatic Breast Cancer.  Ongoing preclinical/clinical trials will define the role of the Wnt pathway in different therapeutic areas and open new opportunities.

Leptin Is Associated with Poor Clinical Outcomes and Promotes Clear Cell Renal Cell Carcinoma Progression

Emerging evidence has shown the oncogenic roles of leptin in modulating cancer progression in addition to its original roles. Analyses of transcriptomic data and patients’ clinical information have revealed leptin’s prognostic significance in renal cell carcinoma (RCC). However, its biological effects on RCC progression have not yet been explored. Clinical and transcriptomic data of a RCC cohort of 603 patients were retrieved from The Cancer Genome Atlas (TCGA) and analyzed to reveal the correlation of leptin with clinical outcomes and the hierarchical clustering of gene signatures based on leptin levels. In addition, cox univariate and multivariate regression analyses, cell migration upon leptin treatment, identification of putative leptin-regulated canonical pathways via ingenuity pathway analysis (IPA), and the investigation of induction of Wnt5a, ROR2, and Jun N-terminal Kinases (JNK) phosphorylation activation were performed. We first observed a correlation of high leptin levels and poor outcomes in RCC patients. Knowledge-based analysis by IPA indicated the induction of cancer cell migration by leptin, which was manifested via direct leptin treatment in the RCC cell lines. In RCC patients with high leptin levels, the planar cell polarity (PCP)/JNK signaling pathway was shown to be activated, and genes in the axis, including CTHRC1, FZD2, FZD10, ROR2, WNT2, WNT4, WNT10B, WNT5A, WNT5B, and WNT7B, were upregulated. All of these genes were associated with unfavorable clinical outcomes. WNT5A and ROR2 are pivotal upstream regulators of PCP/JNK signaling, and their correlations with leptin expression levels were displayed by a Pearson correlation analysis. The inhibition of signal transduction by SP600125 reversed leptin-mediated cell migration properties in RCC cell lines. The results indicate the prognostic impact of leptin on RCC patients and uncover its ability to promote cell migration via PCP/JNK signaling.

The WNT/ROR Pathway in Cancer: From Signaling to Therapeutic Intervention

The WNT pathway is one of the major signaling cascades frequently deregulated in human cancer. While research had initially focused on signal transduction centered on β-catenin as a key effector activating a pro-tumorigenic transcriptional response, nowadays it is known that WNT ligands can also induce a multitude of β-catenin-independent cellular pathways. Traditionally, these comprise WNT/planar cell polarity (PCP) and WNT/Ca²⁺ signaling. In addition, signaling via the receptor tyrosine kinase-like orphan receptors (RORs) has gained increasing attention in cancer research due to their overexpression in a multitude of tumor entities. Active WNT/ROR signaling has been linked to processes driving tumor development and progression, such as cell proliferation, survival, invasion, or therapy resistance. In adult tissue, the RORs are largely absent, which has spiked the interest in them for targeted cancer therapy. Promising results in preclinical and initial clinical studies are beginning to unravel the great potential of such treatment approaches. In this review, we summarize seminal findings on the structure and expression of the RORs in cancer, their downstream signaling, and its output in regard to tumor cell function. Furthermore, we present the current clinical anti-ROR treatment strategies and discuss the state-of-the-art, as well as the challenges of the different approaches.

Organization of Protein Tyrosine Kinase-7 on Cell Membranes Characterized by Aptamer Probe-Based STORM Imaging

Protein tyrosine kinase-7 (PTK7), as an important membrane receptor, regulates various cellular activities, including cell polarity, movement, migration, and invasion. Although lots of research studies focused on revealing its functions from the aspect of the expression of the gene and protein are present, the relationship between the spatial distribution at the single-molecule level and the function remains unclear. Through combining aptamer probe labeling and super-resolution imaging technology, after verifying the specificity and superiority of the aptamer probe, a more significant clustering distribution of PTK7 is found on the MCF10A cell basal membrane than on the apical membrane, which is thought to be related to their specific functions on different membranes. By exploring the relationship between the assembly of PTK7 and lipid rafts, actin cytoskeleton, and carbohydrate chains on the membrane, the unique distribution of PTK7 on disparate membranes is revealed to be probably because of the varied dominant position of these three factors. These findings present the detailed spatial information of PTK7 and the related potential organization mechanism on the cell membrane, which will facilitate a better understanding of the relationship between the molecular assembly and its function, as well as the overall structure of the cell membrane.

Gene Expression in Patient-Derived Neural Progenitors Implicates WNT5A Signaling in the Etiology of Schizophrenia

BACKGROUND

Genome-wide association studies of schizophrenia have demonstrated that variations in noncoding regions are responsible for most of the common variation heritability of the disease. It is hypothesized that these risk variants alter gene expression. Therefore, studying alterations in gene expression in schizophrenia may provide a direct approach to understanding the etiology of the disease. In this study we use cultured neural progenitor cells derived from olfactory neuroepithelium (CNON cells) as a genetically unaltered cellular model to elucidate the neurodevelopmental aspects of schizophrenia.

METHODS

We performed a gene expression study using RNA sequencing of CNON cells from 111 control subjects and 144 individuals with schizophrenia. Differentially expressed genes were identified with DESeq2 software, using covariates to correct for sex, age, library batches, and 1 surrogate variable component.

RESULTS

A total of 80 genes were differentially expressed (false discovery rate < 10%), showing enrichment in cell migration, cell adhesion, developmental process, synapse assembly, cell proliferation, and related Gene Ontology categories. Cadherin and Wnt signaling pathways were positive in overrepresentation test, and, in addition, many genes were specifically involved in WNT5A signaling. The differentially expressed genes were modestly, but significantly, enriched in the genes overlapping single nucleotide polymorphisms with genome-wide significant association from the Psychiatric Genomics Consortium genome-wide association study of schizophrenia. We also found substantial overlap with genes associated with other psychiatric disorders or brain development, enrichment in the same Gene Ontology categories as genes with mutations de novo in schizophrenia, and studies of induced pluripotent stem cell-derived neural progenitor cells.

CONCLUSIONS

CNON cells are a good model of the neurodevelopmental aspects of schizophrenia and can be used to elucidate the etiology of the disorder.

The multiple ways Wnt signaling contributes to acute leukemia pathogenesis

WNT proteins constitute a very conserved family of secreted glycoproteins that act as short-range ligands for signaling with critical roles in hematopoiesis, embryonic development, and tissue homeostasis. These proteins transduce signals via the canonical pathway, which is β-catenin-mediated and better-characterized, or via more diverse noncanonical pathways that are β-catenin independent and comprise the planar cell polarity (PCP) pathway and the WNT/Ca⁺⁺ pathways. Several proteins regulate Wnt signaling through a variety of sophisticated mechanisms. Disorders within the pathway can contribute to various human diseases, and the dysregulation of Wnt pathways by different molecular mechanisms is implicated in the pathogenesis of many types of cancer, including the hematological malignancies. The types of leukemia differ considerably and can be subdivided into chronic, myeloid or lymphocytic, and acute, myeloid or lymphocytic, leukemia, according to the differentiation stage of the predominant cells, the progenitor lineage, the diagnostic age strata, and the specific molecular drivers behind their development. Here, we review the role of Wnt signaling in normal hematopoiesis and discuss in detail the multiple ways canonical Wnt signaling can be dysregulated in acute leukemia, including alterations in gene expression and protein levels, epigenetic regulation, and mutations. Furthermore, we highlight the different impacts of these alterations, considering the distinct forms of the disease, and the therapeutic potential of targeting Wnt signaling.

Prospects for pharmacological targeting of pseudokinases

Pseudokinases are members of the protein kinase superfamily but signal primarily through noncatalytic mechanisms. Many pseudokinases contribute to the pathologies of human diseases, yet they remain largely unexplored as drug targets owing to challenges associated with modulation of their biological functions. Our understanding of the structure and physiological roles of pseudokinases has improved substantially over the past decade, revealing intriguing similarities between pseudokinases and their catalytically active counterparts. Pseudokinases often adopt conformations that are analogous to those seen in catalytically active kinases and, in some cases, can also bind metal cations and/or nucleotides. Several clinically approved kinase inhibitors have been shown to influence the noncatalytic functions of active kinases, providing hope that similar properties in pseudokinases could be pharmacologically regulated. In this Review, we discuss known roles of pseudokinases in disease, their unique structural features and the progress that has been made towards developing pseudokinase-directed therapeutics.

Non-canonical Wnt signalling regulates scarring in biliary disease via the planar cell polarity receptors

The number of patients diagnosed with chronic bile duct disease is increasing and in most cases these diseases result in chronic ductular scarring, necessitating liver transplantation. The formation of ductular scaring affects liver function; however, scar-generating portal fibroblasts also provide important instructive signals to promote the proliferation and differentiation of biliary epithelial cells. Therefore, understanding whether we can reduce scar formation while maintaining a pro-regenerative microenvironment will be essential in developing treatments for biliary disease. Here, we describe how regenerating biliary epithelial cells express Wnt-Planar Cell Polarity signalling components following bile duct injury and promote the formation of ductular scars by upregulating pro-fibrogenic cytokines and positively regulating collagen-deposition. Inhibiting the production of Wnt-ligands reduces the amount of scar formed around the bile duct, without reducing the development of the pro-regenerative microenvironment required for ductular regeneration, demonstrating that scarring and regeneration can be uncoupled in adult biliary disease and regeneration.

ROR2 induces cell apoptosis via activating IRE1α/JNK/CHOP pathway in high-grade serous ovarian carcinoma in vitro and in vivo

Background

Epithelial ovarian cancer (EOC) is the most lethal cancer in female genital tumors. New disease markers and novel therapeutic strategies are urgent to identify considering the current status of treatment. Receptor tyrosine kinases family plays critical roles in embryo development and disease progression. However, ambivalent research conclusions of ROR2 make its role in tumor confused and the underlying mechanism is far from being understood. In this study, we sought to clarify the effects of ROR2 on high-grade serous ovarian carcinoma (HGSOC) cells and reveal the mechanism.

Methods

Immunohistochemistry assay and western-blot assay were used to detect proteins expression. ROR2 overexpression adenovirus and Lentivirus were used to create ROR2 overexpression model in vitro and in vivo, respectively. MTT assay, colony formation assay and transwell assay were used to measure the proliferation, invasion and migration ability of cancer cells. Flow cytometry assay was used to detect cell apoptosis rate. Whole transcriptome analysis was used to explore the differentially expressed genes between ROR2 overexpression group and negative control group. SiRNA targeted IRE1α was used to knockdown IRE1α. Kira6 was used to inhibit phosphorylation of IRE1α.

Results

Expression of ROR2 was significantly lower in HGSOC tissues compared to normal fallopian tube epithelium or ovarian surface epithelium tissues. In HGSOC cohort, patients with advanced stages or positive lymph nodes were prone to express lower ROR2. Overexpression of ROR2 could repress the proliferation of HGSOC cells and induce cell apoptosis. RNA sequencing analysis indicated that ROR2 overexpression could induce unfold protein response. The results were also confirmed by upregulation of BIP and phosphorylated IRE1α. Furthermore, pro-death factors like CHOP, phosphorylated JNK and phosphorylated c-Jun were also upregulated. IRE1α knockdown or Kira6 treatment could reverse the apoptosis induced by ROR2 overexpression. Finally, tumor xenograft experiment showed ROR2 overexpression could significantly repress the growth rate and volume of transplanted tumors.

Conclusions

Taken together, ROR2 downregulation was associated with HGSOC development and progression. ROR2 overexpression could repress cell proliferation and induce cell apoptosis in HGSOC cells. And the underlying mechanism might be the activation of IRE1α/JNK/CHOP pathway induced by ROR2.

ENST00000489707.5 Is a Preferred Alternative Splicing Variant of PTK7 in Adrenocortical Cancer and Shows Potential Prognostic Value

Background

This study aimed to explore the transcript preference of PTK7 in adrenocortical cancer (ACC), the prognostic value, and the potential underlying genetic alterations.

Material/Methods

Data from the Cancer Genome Atlas-Adrenocortical Cancer (TCGA-ACC) and the Genotype-Tissue Expression (GTEx)-normal adrenal gland were used for analysis.

Results

A non-canonical alternative transcript, ENST00000489707.5, which only encodes an extracellular immunoglobulin (Ig)-like domain and an intracellular kinase domain, is the dominant isoform of PTK7 in both ACC and normal adrenal gland. Its expression percentage was significantly higher in ACC than in normal adrenal gland. ACC tissues showed preferred expression of this transcript compared with other cancers with known PTK7 expression. Prognostic analysis showed that ENST00000489707.5 had independent prognostic value in progression-free survival (PFS) (HR: 1.227, 95%CI: 1.077–1.398, p=0.002) and disease-specific survival (DSS) (HR: 1.419, 95%CI: 1.154–1.745, p=0.001) after adjustment of other risk factors. cg20819617 methylation was negatively correlated with both PTK7 and ENST00000489707.5 expression.

Conclusions

ENST00000489707.5 is a preferred alternative splicing product of PTK7, with a significantly increased proportion in ACC compared with other cancers. Its expression shows potential prognostic value in terms of PFS and DSS in ACC patients. The methylation status of cg20819617 might play a critical role in modulating PTK7 transcription and ENST00000489707.5 expression.