In vivo cleaved CDCP1 promotes early tumor dissemination via complexing with activated β1 integrin and induction of FAK/PI3K/Akt motility signaling

Sargassum polysaccharide attenuates osteoarthritis in rats and is associated with the up-regulation of the ITGβ1-PI3K-AKT signaling pathway

Background

Osteoarthritis (OA) presents a formidable challenge, characterized by as-yet-unclear mechanical intricacies within cartilage and the dysregulation of bone homeostasis. Our preliminary data revealed the encouraging potential of a Sargassum polysaccharide (SP), in promoting chondrogenesis. The aim of our study is to comprehensively assess the therapeutic effects of SP on OA models and further elucidate its potential mechanism.

Methods

The protective effects of SP were initially evaluated in an inflammation-induced human chondrocyte (C28) cell model. CCK-8 assays, Alcian blue staining, RT-qPCR and Western blotting were used to verify the chondrogenesis of SP in vitro. To assess the efficacy of SP in vivo, surgically induced medial meniscus destabilization (DMM) OA rats underwent an 8-week SP treatment. The therapeutic effects of SP in OA rats were comprehensively evaluated using X-ray imaging, micro-computed tomography (μ-CT), histopathological analysis, as well as immunohistochemical and immunofluorescent staining. Following these assessments, we delved into the potential signaling pathways of SP in inflammatory chondrocytes utilizing RNA-seq analysis. Validation of these findings was conducted through RT-qPCR and western blotting techniques.

Results

SP significantly enhance the viability of C28 chondrocytes, and increased the secretion of acidic glycoproteins. Moreover, SP stimulated the expression of chondrogenic genes (Aggrecan, Sox9, Col2a1) and facilitated the synthesis of Collagen II protein in C28 inflammatory chondrocytes. In vivo experiments revealed that SP markedly ameliorated knee joint stenosis, alleviated bone and cartilage injuries, and reduced the histopathological scores in the OA rats. μ-CT analysis confirmed that SP lessened bone impairments in the medial femoral condyle and the subchondral bone of the tibial plateau, significantly improving the microarchitectural parameters of the subchondral bone. Histopathological analyses indicated that SP notably enhanced cartilage quality on the surface of the tibial plateau, leading to increased cartilage thickness and area. Immunohistochemistry staining and immunofluorescence staining corroborated these findings by showing a significant promotion of Collagen II expression in OA joints treated with SP. RNA-seq analysis suggest that SP's effects were mediated through the regulation of the ITGβ1-PI3K-AKT signaling axis, thereby stimulating chondrogenesis. Verification through RT-qPCR and Western blot analyses confirmed that SP significantly upregulated the expression of ITGβ1, p110δ, AKT1, ACAN, and Col2a1. Notably, knock-down of ITGβ1 using siRNA in C28 chondrocytes inhibited the expression of ITGβ1, p110δ, AKT1, and ACAN. However, these inhibitory effects were not completely reversed by supplemental SP intervention.

Conclusions

In summary, our findings reveal that SP significantly enhances chondrogenesis both in vitro and in vivo, alleviating OA progression both in bone and cartilage. The observed beneficial effects are intricately linked to the activation of the ITGβ1-PI3K-AKT signaling axis.

The translational potential of this article

Our research marks the first instance unveiling the advantageous effects and underlying mechanisms of SP in OA treatment. With its clinical prospects, SP presents compelling new evidence for the advancement of a next-generation polysaccharide drug for OA therapy.

WISP-1 Regulates Cardiac Fibrosis by Promoting Cardiac Fibroblasts' Activation and Collagen Processing

Hypertension induces cardiac fibrotic remodelling characterised by the phenotypic switching of cardiac fibroblasts (CFs) and collagen deposition. We tested the hypothesis that Wnt1-inducible signalling pathway protein-1 (WISP-1) promotes CFs' phenotypic switch, type I collagen synthesis, and in vivo fibrotic remodelling. The treatment of human CFs (HCFs, n = 16) with WISP-1 (500 ng/mL) induced a phenotypic switch (α-smooth muscle actin-positive) and type I procollagen cleavage to an intermediate form of collagen (pC-collagen) in conditioned media after 24h, facilitating collagen maturation. WISP-1-induced collagen processing was mediated by Akt phosphorylation via integrin β1, and disintegrin and metalloproteinase with thrombospondin motifs 2 (ADAMTS-2). WISP-1 wild-type (WISP-1+/+) mice and WISP-1 knockout (WISP-1-/-) mice (n = 5-7) were subcutaneously infused with angiotensin II (AngII, 1000 ng/kg/min) for 28 days. Immunohistochemistry revealed the deletion of WISP-1 attenuated type I collagen deposition in the coronary artery perivascular area compared to WISP-1+/+ mice after a 28-day AngII infusion, and therefore, the deletion of WISP-1 attenuated AngII-induced cardiac fibrosis in vivo. Collectively, our findings demonstrated WISP-1 is a critical mediator in cardiac fibrotic remodelling, by promoting CFs' activation via the integrin β1-Akt signalling pathway, and induced collagen processing and maturation via ADAMTS-2. Thereby, the modulation of WISP-1 levels could provide potential therapeutic targets in clinical treatment.

Extracellular proteolysis in cancer: Proteases, substrates, and mechanisms in tumor progression and metastasis

A vast ensemble of extracellular proteins influences the development and progression of cancer, shaped and reshaped by a complex network of extracellular proteases. These proteases, belonging to the distinct classes of metalloproteases, serine proteases, cysteine proteases, and aspartic proteases, play a critical role in cancer. They often become dysregulated in cancer, with increases in pathological protease activity frequently driven by the loss of normal latency controls, diminished regulation by endogenous protease inhibitors, and changes in localization. Dysregulated proteases accelerate tumor progression and metastasis by degrading protein barriers within the extracellular matrix (ECM), stimulating tumor growth, reactivating dormant tumor cells, facilitating tumor cell escape from immune surveillance, and shifting stromal cells toward cancer-promoting behaviors through the precise proteolysis of specific substrates to alter their functions. These crucial substrates include ECM proteins and proteoglycans, soluble proteins secreted by tumor and stromal cells, and extracellular domains of cell surface proteins, including membrane receptors and adhesion proteins. The complexity of the extracellular protease web presents a significant challenge to untangle. Nevertheless, technological strides in proteomics, chemical biology, and the development of new probes and reagents are enabling progress and advancing our understanding of the pivotal importance of extracellular proteolysis in cancer.

Integrins as the pivotal regulators of cisplatin response in tumor cells

Cisplatin (CDDP) is a widely used first-line chemotherapeutic drug in various cancers. However, CDDP resistance is frequently observed in cancer patients. Therefore, it is required to evaluate the molecular mechanisms associated with CDDP resistance to improve prognosis among cancer patients. Integrins are critical factors involved in tumor metastasis that regulate cell-matrix and cell-cell interactions. They modulate several cellular mechanisms including proliferation, invasion, angiogenesis, polarity, and chemo resistance. Modification of integrin expression levels can be associated with both tumor progression and inhibition. Integrins are also involved in drug resistance of various solid tumors through modulation of the tumor cell interactions with interstitial matrix and extracellular matrix (ECM). Therefore, in the present review we discussed the role of integrin protein family in regulation of CDDP response in tumor cells. It has been reported that integrins mainly promoted the CDDP resistance through interaction with PI3K/AKT, MAPK, and WNT signaling pathways. They also regulated the CDDP mediated apoptosis in tumor cells. This review paves the way to suggest the integrins as the reliable therapeutic targets to improve CDDP response in tumor cells.

CD6 triggers actomyosin cytoskeleton remodeling after binding to its receptor complex

The T cell marker CD6 regulates both T cells and target cells during inflammatory responses by interacting with its receptors. However, only a few receptors binding to the extracellular domains of CD6 have been identified, and cellular events induced by CD6 engagement with its receptors in target cells remain poorly understood. In this study, we identified CD44 as a novel CD6 receptor by proximity labeling and confirmed the new CD6-CD44 interaction by biochemical and biophysical approaches. CD44 and the other 2 known CD6 receptors, CD166 and CDCP1, were distributed diffusely on resting retinal pigment epithelium (RPE) cells but clustered together to form a receptor complex upon CD6 binding. CD6 stimulation induced dramatic remodeling of the actomyosin cytoskeleton in RPE cells mediated by activation of RhoA, and Rho-associated kinase signaling, resulting in increased myosin II phosphorylation. Such actomyosin activation triggered the disassembly of tight junctions responsible for RPE barrier integrity in a process that required all components of the tripartite CD6 receptor complex. These data provided new insights into the mechanisms by which CD6 mediates T cell-driven disruption of tissue barriers during inflammation.

The roles of proteases in prostate cancer

Since the proposition of the pro-invasive activity of proteolytic enzymes over 70 years ago, several roles for proteases in cancer progression have been established. About half of the 473 active human proteases are expressed in the prostate and many of the most well-characterized members of this enzyme family are regulated by androgens, hormones essential for development of prostate cancer. Most notably, several kallikrein-related peptidases, including KLK3 (prostate-specific antigen, PSA), the most well-known prostate cancer marker, and type II transmembrane serine proteases, such as TMPRSS2 and matriptase, have been extensively studied and found to promote prostate cancer progression. Recent findings also suggest a critical role for proteases in the development of advanced and aggressive castration-resistant prostate cancer (CRPC). Perhaps the most intriguing evidence for this role comes from studies showing that the protease-activated transmembrane proteins, Notch and CDCP1, are associated with the development of CRPC. Here, we review the roles of proteases in prostate cancer, with a special focus on their regulation by androgens.

Mechanistic insights into CDCP1 clustering on non-small-cell lung cancer membranes revealed by super-resolution fluorescent imaging

CDCP1 is a transmembrane protein that is involved in a variety of important biological processes and upregulated in a variety of human solid malignancies; however, its spatial distribution and variation at the molecular level remain unclear. To solve this problem, we first analyzed its expression level and prognostic implications in lung cancer. Then, we used super-resolution microscopy to reveal the spatial organization of CDCP1 at different levels, and found that cancer cells generated more and larger CDCP1 clusters than normal cells. Furthermore, we found that CDCP1 can be integrated into larger and denser clusters as functional domains upon activation. Our findings elucidated the significant differences of CDCP1 clustering characteristics between cancer and normal cells, and revealed the relationship between its distribution and function, which will contribute to a comprehensive understanding of its oncogenic mechanism, and will be of great help for the development of CDCP1-targeted drugs for lung cancer.

Detection and Isolation of Circulating Tumor Cells from Breast Cancer Patients Using CUB Domain-Containing Protein 1

In cancer metastasis, single circulating tumor cells (CTCs) in the blood and disseminated tumor cells (DTCs) in the bone marrow mediate cancer metastasis. Because suitable biomarker proteins are lacking, CTCs and DTCs with mesenchymal attributes are difficult to isolate from the bulk of normal blood cells. To establish a procedure allowing the isolation of such cells, we analyzed the cell line BC-M1 established from DTCs in the bone marrow of a breast cancer patient by stable isotope labeling by amino acids in cell culture (SILAC) and mass spectrometry. We found high levels of the transmembrane protein CUB domain-containing protein 1 (CDCP1) in breast cancer cell lines with mesenchymal attributes. Peripheral blood mononuclear cells were virtually negative for CDCP1. Confirmation in vivo by CellSearch revealed CDCP1-positive CTCs in 8 of 30 analyzed breast cancer patients. Only EpCam-positive CTCs were enriched by CellSearch. Using the extracellular domain of CDCP1, we established a magnetic-activated cell sorting (MACS) approach enabling also the enrichment of EpCam-negative CTCs. Thus, our approach is particularly suited for the isolation of mesenchymal CTCs with downregulated epithelial cancer that occur, for example, in triple-negative breast cancer patients who are prone to therapy failure.

Citrate and hydroxycinnamate derivatives from Mume Fructus protect LPS-injured intestinal epithelial cells by regulating the FAK/PI3K/AKT signaling pathway

ETHNOPHARMACOLOGICAL RELEVANCE

Mume Fructus (MF) is processed from the near-ripe fruit of Prunus mume (Siebold) Siebold & Zucc by drying at low temperature until the color turns black. MF is often used in Chinese medicine for the treatment of chronic diarrhea and dysentery. Previous studies have shown that the active components of MF against Crohn's disease (CD) are mainly citrate and hydroxycinnamate derivatives, which can alleviate the CD-induced inflammatory response and intestinal barrier damage. However, their molecular mechanisms on CD still need further elucidation.

AIM OF THE STUDY

To investigate the protective effects and underlying mechanisms of citrate and hydroxycinnamate derivatives in MF on intestinal epithelial injury.

MATERIALS AND METHODS

Network pharmacology technology was used to predict the anti-CD targets and molecular mechanisms of 4 citrate and 11 hydroxycinnamate derivative prototypes and 5 hydroxycinnamate derivative metabolites in the 40% ethanol fraction of MF (MFE40), the active anti-CD ingredient group of MF. Lipopolysaccharide (LPS)-treated IEC-6 cells were used to investigate the effects of the above components on the proliferation of damaged IEC-6 cells and to verify the molecular mechanism of their regulation on the FAK/PI3K/AKT signaling pathways for the promotion of the proliferation of IEC-6 cells.

RESULTS

A "compound-target-pathway" network was constructed based on network pharmacology analysis, including 20 citrate and hydroxycinnamate derivatives that target 316 core proteins and 36 CD-related pathways, of which PI3K-AKT pathway and focal adhesion were the most enriched pathways. Further cell validation experiments showed that 1 citric acid (CA) compound and 10 hydroxycinnamate derivatives, including 3-O-caffeoylquinic acid (3CQA), 4-O-caffeoylquinic acid (4CQA), 5-O-caffeoylquinic acid (5CQA), caffeic acid (CFA), p-coumaric acid (PCMA), m-coumaric acid (MCMA), ferulic acid (FUA), isoferulic acid (IFUA), 3-hydroxyphenylpropionic acid (3HPPA) and hippuric acid (HPP), could promote the proliferation of IEC-6 cells and inhibit the damage of LPS to IEC-6 cells. Ethyl caffeate (ECFA), a hydroxycinnamic acid derivative, had no effect on promoting the proliferation of IEC-6 cells and was weak in inhibiting the damage of IEC-6 cells caused by LPS. Further mechanistic verification experiments showed that 7 citrate and hydroxycinnamate derivatives (CA, CFA, 3CQA, MCMA, FUA, 3HPPA, and HPP) could upregulate the expression of p-FAK, p-PI3K, and p-AKT proteins. Among them, CA had the better effect on activating the FAK-PI3K-AKT signaling pathway.

CONCLUSIONS

Citrate and hydroxycinnamate derivatives in MF can ameliorate LPS-induced intestinal epithelial cell injury to demonstrate potential for Crohn's disease alleviation. This protective effect can be achieved by upregulating FAK/PI3K/AKT pathway.

CDCP1 expression is frequently increased in aggressive urothelial carcinoma and promotes urothelial tumor progression

The prognosis of patients with advanced urothelial carcinoma (UC) remains poor and improving treatment continues to be a major medical need. CUB domain containing protein 1 (CDCP1) is a known oncogene in various types of solid cancers and its overexpression is associated with impaired prognosis. However, its role in UC remains undetermined. Here we assessed the clinical relevance of CDCP1 in two cohorts of UC at different stages of the disease. Immunohistochemistry showed that CDCP1 is highly expressed in advanced UC, which significantly correlates with shorter overall survival. Importantly, the basal/squamous UC subtype showed significantly enriched CDCP1 at the mRNA and protein levels. The functional role of CDCP1 overexpression was assessed taking advantage of ex vivo organoids derived from the CDCP1^pcLSL/+ transgenic mouse model. Furthermore, CDCP1 knockout UC cell lines were generated using CRISPR/Cas9 technology. Interestingly, CDCP1 overexpression significantly induced the activation of MAPK/ERK pathways in ex vivo organoids and increased their proliferation. Similarly, CDCP1 knockout in UC cell lines reduced their proliferation and migration, concomitant with MAPK/ERK pathway activity reduction. Our results highlight the relevance of CDCP1 in advanced UC and demonstrate its oncogenic role, suggesting that targeting CDCP1 could be a rational therapeutic strategy for the treatment of advanced UC.

ZCCHC4 Promotes Osteosarcoma Progression by Upregulating ITGB1

Zinc finger CCHC-type containing 4 (ZCCHC4), RNA binding protein, has been reported to mediate rRNA methylation and affect tumor cell proliferation. However, the role of ZCCHC4 in the regulation of osteosarcoma (OS) remains unknown. ZCCHC4 was highly expressed in OS tissues and cell lines. Overexpression or silencing of ZCCHC4 promoted or inhibited cell proliferation, epithelial-mesenchymal transition (EMT), and motility. Additionally, we proved that ZCCHC4 facilitates OS progression through upregulating integrin β1 (ITGB1). In the animal model, ZCCHC4 knockdown reduced OS tumor growth and metastases in vivo. Our findings showed that ZCCHC4 promoted the progression of OS through upregulating ITGB1 and suggested that inhibition of ZCCHC4 could be a novel therapeutic strategy for OS.

Overexpression of Laminin 5γ2 Chain Correlates with Tumor Cell Proliferation, Invasion, and Poor Prognosis in Laryngeal Squamous Cell Carcinoma

Objective

Laryngeal squamous cell carcinoma (LSCC) is a common malignant tumor. Laminin 5γ2 chain (LAMC2) was reported to be associated with tumorigenesis. This study explored the role of LAMC2 on LSCC progression by regulating the integrinβ1/FAK/Src/AKT pathway.

Methods

The level of LAMC2 in 46 LSCC patients was detected by qRT-PCR and western blot. Then the relationship between LAMC2 expression and LSCC malignancy as well as prognosis was analyzed, and the effect of LAMC2 expression on LSCC patient survival was also analyzed using the Kaplan–Meier survival curves. Afterwards, the LSCC cells were transfected with LAMC2 overexpression and knockdown vectors, the effect of LAMC2 on LSCC cell viability, proliferation ability, cell cycle, cell migration, and invasion were detected by CCK-8, colony formation, flow cytometry, wound healing, and Transwell assays. The expression of EMT-related biomarkers and integrin β1/FAK/Src/AKT signaling-related proteins was detected by western blot. Moreover, the effect of LAMC2 on LSCC tumor growth was evaluated by in vivo xenograft experiments and western blot.

Results

LAMC2 was expressed at high level in LSCC tissues and associated with poor prognosis. LAMC2 overexpression increased TU177 cell viability, proliferation ability, promoted cell cycle, cell migration, and invasion capacity. The expression of N-cadherin, vimentin, and integrinβ1/FAK/Src/AKT related proteins was increased, while the expression of E-cadherin protein was decreased. When the LAMC2 knockdown in AMC-HN-8 cells had opposite effects. Furthermore, shLAMC2 decreased tumor volume and the expression of LAMC2, Ki-67 and integrinβ1, but increased the expression of E-cadherin in LSCC tumor-bearing mice.

Conclusion

The findings suggested that LAMC2 was overexpressed in LSCC and correlated with poor prognosis. LAMC2 knockdown inhibited LSCC progression by regulating the integrinβ1/FAK/Src/AKT signaling pathway. Therefore, LAMC2 could be a target for LSCC therapy.

COL1A1: A novel oncogenic gene and therapeutic target in malignancies

Collagen type I alpha 1 (COL1A1), a member of the collagen family, is involved in epithelial-mesenchymal transition, which is closely linked to malignant tumorigenesis. COL1A1 is highly expressed in various cancers and regulates various cellular processes, including cell proliferation, metastasis, apoptosis, and cisplatin resistance. COL1A1 is also associated with cancer progression and prognosis; elevated COL1A1 expression is associated with poor prognosis in cancer patients. However, the main role of COL1A as a cancer-promoting factor in specific tumors has not been reported. Additionally, the protein levels and mechanisms of action of this protein differ among tumor types. This review discusses current research progress concerning COL1A1 in different tumor types, and then summarizes its contributions to cancer progression, thus providing a basis for follow-up research and potential targets for cancer treatment.

CUB Domain-Containing Protein 1 (CDCP1) Is a Target for Radioligand Therapy in Castration-Resistant Prostate Cancer, including PSMA Null Disease

PURPOSE

With the improvement in overall survival with 177Lu-PSMA 617, radioligand therapy (RLT) is now a viable option for patients with metastatic castration-resistant prostate cancer (mCRPC). However, responses are variable, in part due to low PSMA expression in 30% of patients. Herein, we evaluated whether the cell surface protein CUB domain-containing protein 1 (CDCP1) can be exploited to treat mCRPC with RLT, including in PSMA-low subsets.

EXPERIMENTAL DESIGN

CDCP1 levels were evaluated using RNA sequencing from 119 mCRPC biopsies. CDCP1 levels were assessed in 17 post-enzalutamide- or abiraterone-treated mCRPC biopsies, 12 patient-derived xenografts (PDX), and prostate cancer cell lines. 4A06, a recombinant human antibody that targets the CDCP1 ectodomain, was labeled with Zr-89 or Lu-177 and tested in tumor-bearing mice.

RESULTS

CDCP1 expression was observed in 90% of mCRPC biopsies, including small-cell neuroendocrine (SCNC) and adenocarcinomas with low FOLH1 (PSMA) levels. Fifteen of 17 evaluable mCRPC biopsies (85%) demonstrated membranous CDCP1 expression, and 4 of 17 (23%) had higher CDCP1 H-scores compared with PSMA. CDCP1 was expressed in 10 of 12 PDX samples. Bmax values of approximately 22,000, 6,200, and 2,800 fmol/mg were calculated for PC3, DU145, and C4-2B human prostate cancer cells, respectively. 89Zr-4A06 PET detected six human prostate cancer xenografts, including PSMA-low tumors. 177Lu-4A06 significantly suppressed growth of DU145 and C4-2B xenografts.

CONCLUSIONS

The data provide the first evidence supporting CDCP1-directed RLT to treat mCRPC. Expanded studies are warranted to determine whether CDCP1 is a viable drug target for patients with mCPRC.

Antibody-Based Approaches to Target Pancreatic Tumours

Pancreatic cancer is an aggressive cancer with a dismal prognosis. This is due to the difficulty to detect the disease at an early and curable stage. In addition, only limited treatment options are available, and they are confronted by mechanisms of resistance. Monoclonal antibody (mAb) molecules are highly specific biologics that can be directly used as a blocking agent or modified to deliver a drug payload depending on the desired outcome. They are widely used to target extracellular proteins, but they can also be employed to inhibit intracellular proteins, such as oncoproteins. While mAbs are a class of therapeutics that have been successfully employed to treat many cancers, they have shown only limited efficacy in pancreatic cancer as a monotherapy so far. In this review, we will discuss the challenges, opportunities and hopes to use mAbs for pancreatic cancer treatment, diagnostics and imagery.

Src activation in lipid rafts confers epithelial cells with invasive potential to escape from apical extrusion during cell competition

Abnormal/cancerous cells within healthy epithelial tissues undergo apical extrusion to protect against carcinogenesis, although they acquire invasive capacity once carcinogenesis progresses. However, the molecular mechanisms by which cancer cells escape from apical extrusion and invade surrounding tissues remain elusive. In this study, we demonstrate a molecular mechanism for cell fate switching during epithelial cell competition. We found that during competition within epithelial cell layers, Src transformation promotes maturation of focal adhesions and degradation of extracellular matrix. Src-transformed cells underwent basal delamination by Src activation within sphingolipid/cholesterol-enriched membrane microdomains/lipid rafts, whereas they were apically extruded when Src was outside of lipid rafts. A comparative analysis of contrasting phenotypes revealed that activation of the Src-STAT3-MMP axis through lipid rafts was required for basal delamination. CUB-domain-containing protein 1 (CDCP1) was identified as an Src-activating scaffold and as a Met regulator in lipid rafts, and its overexpression induced basal delamination. In renal cancer models, CDCP1 promoted epithelial-mesenchymal transition-mediated invasive behavior by activating the Src-STAT3-MMP axis through Met activation. Overall, these results suggest that spatial activation of Src signaling in lipid rafts confers resistance to apical extrusion and invasive potential on epithelial cells to promote carcinogenesis.

Targeting CDCP1 gene transcription coactivated by BRD4 and CBP/p300 in castration-resistant prostate cancer

CUB domain-containing protein 1 (CDCP1), a transmembrane protein with tumor pro-metastatic activity, is highly expressed in late-stage and castrate-resistant prostate cancer (CRPC). However, the molecular mechanism driving CDCP1 overexpression in CRPC progress remains elusive. Here we report that transcription cofactors BRD4 and CBP/p300 co-regulate transcriptional expression of CDCP1 in CRPC tumorigenesis. In contrast to androgen receptor (AR) in CRPC, increased expression of BRD4 and CBP/p300 is strongly correlated with CDCP1 gene amplification. Combined knockdown or dual-inhibition of BRD4 and CBP/p300 down-regulated CDCP1 transcription and downstream PI3K/AKT and/or SRC/MAPK signaling pathways in CRPC cells much more so than single-protein perturbation. Our biochemical and structural analyses further showed that NEO2734, a dual-inhibitor targeting BRD4 and p300 bromodomains exhibits greater efficacy than single inhibitors for BRD4 or CBP/p300 in suppressing CDCP1 transcriptional expression and its downstream signaling pathways in CRPC cell proliferation and metastasis. Our study illustrates that targeting CDCP1 through dual-inhibition of BRD4 and CBP/p300 represents a synergistic therapeutic strategy for new treatment of CRPC.

Molecular mechanism by which CDCP1 promotes proneural-mesenchymal transformation in primary glioblastoma

Background

Compared with the proneural (PN) subtype of glioblastoma (GBM), the mesenchymal (MES) subtype is more invasive and immune evasive and is closely related to poor prognosis. Here, we used transcriptome data and experimental evidence to indicate that CUB domain-containing protein 1 (CDCP1) is a novel regulator that facilitates the transformation of PN-GBM to MES-GBM.

Methods

The mRNA expression data of CDCP1 in glioma were collected from the TCGA, CGGA and GEO databases, and in vitro experiments verified CDCP1 expression in glioma tissue samples. Independent prognostic analysis revealed the correlation of the CDCP1 expression level and patient survival. Bioinformatics analysis and experiments verified the biological function of CDCP1. Multivariate proportional hazards models and a PPI network were used to select key genes. A prognostic risk model for predicting the survival of glioma patients was constructed based on the selected genes.

Results

The results showed that the expression of CDCP1 increased with increasing tumor grade and that the overexpression of CDCP1 correlated with a poor prognosis. CDCP1 was highly expressed in MES-GBM but weakly expressed in PN-GBM. The risk model (considering CDCP1 combined with CD44 and ITGAM expression) could represent a tool for predicting survival and prognosis in glioma patients.

Conclusions

Our study indicates that CDCP1 plays an important role in facilitating the transformation of PN-GBM to MES-GBM.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12935-021-02373-1.

Recent Progress in Understanding the Action of Natural Compounds at Novel Therapeutic Drug Targets for the Treatment of Liver Cancer

Liver cancer is the third most common cause of cancer-related death following lung and stomach cancers. As a highly lethal disease, liver cancer is diagnosed frequently in less developed countries. Natural compounds extracted from herbs, animals and natural materials have been adopted by traditional Chinese medicine (TCM) practices and reported to be effective in the development of new medications for the treatment of diseases. It is important to focus on the mechanisms of action of natural compounds against hepatocellular carcinoma (HCC), particularly in terms of cell cycle regulation, apoptosis induction, autophagy mediation and cell migration and invasion. In this review, we characterize novel representative natural compounds according to their pharmacologic effects based on recently published studies. The aim of this review is to summarize and explore novel therapeutic drug targets of natural compounds, which could accelerate the discovery of new anticancer drugs.

Targeting a proteolytic neoepitope on CUB domain containing protein 1 (CDCP1) for RAS-driven cancers

Extracellular proteolysis is frequently dysregulated in disease and can generate proteoforms with unique neoepitopes not found in healthy tissue. Here, we demonstrate that Abs that selectively recognize a proteolytic neoepitope on CUB domain containing protein 1 (CDCP1) could enable more effective and safer treatments for solid tumors. CDCP1 is highly overexpressed in RAS-driven cancers, and its ectodomain is cleaved by extracellular proteases. Biochemical, biophysical, and structural characterization revealed that the 2 cleaved fragments of CDCP1 remain tightly associated with minimal proteolysis-induced conformational change. Using differential phage display, we generated recombinant Abs that are exquisitely selective to cleaved CDCP1 with no detectable binding to the uncleaved form. These Abs potently targeted cleaved CDCP1-expressing cancer cells as an Ab-drug conjugate, an Ab-radionuclide conjugate, and a bispecific T cell engager. In a syngeneic pancreatic tumor model, these cleaved-specific Abs showed tumor-specific localization and antitumor activity with superior safety profiles compared with a pan-CDCP1 approach. Targeting proteolytic neoepitopes could provide an orthogonal "AND" gate for improving the therapeutic index.

SRC kinase activator CDCP1 promotes hepatocyte growth factor-induced cell migration/invasion of a subset of breast cancer cells

Cancer invasion and metastasis are the major causes of cancer patient mortality. Various growth factors, including hepatocyte growth factor (HGF), are known to promote cancer invasion and metastasis, but the regulatory mechanisms involved are not fully understood. Here, we show that HGF-promoted migration and invasion of breast cancer cells are regulated by CUB domain–containing protein 1 (CDCP1), a transmembrane activator of SRC kinase. In metastatic human breast cancer cell line MDA-MB-231, which highly expresses the HGF receptor MET and CDCP1, we show that CDCP1 knockdown attenuated HGF-induced MET activation, followed by suppression of lamellipodia formation and cell migration/invasion. In contrast, in the low invasive/nonmetastatic breast cancer cell line T47D, which had no detectable MET and CDCP1 expression, ectopic MET expression stimulated the HGF-dependent activation of invasive activity, and concomitant CDCP1 expression activated SRC and further promoted invasive activity. In these cells, CDCP1 expression dramatically activated HGF-induced membrane remodeling, which was accompanied by activation of the small GTPase Rac1. Analysis of guanine nucleotide exchange factors revealed that ARHGEF7 was specifically required for CDCP1-dependent induction of HGF-induced invasive ability. Furthermore, immunofluorescence staining demonstrated that CDCP1 coaccumulated with ARHGEF7. Finally, we confirmed that the CDCP1-SRC axis was also crucial for HGF and ARHGEF7-RAC1 signaling in MDA-MB-231 cells. Altogether, these results demonstrate that the CDCP1-SRC-ARHGEF7-RAC1 pathway plays an important role in the HGF-induced invasion of a subset of breast cancer cells.

Repurposing Tranexamic Acid as an Anticancer Agent

Tranexamic Acid (TA) is a clinically used antifibrinolytic agent that acts as a Lys mimetic to block binding of Plasminogen with Plasminogen activators, preventing conversion of Plasminogen to its proteolytically activated form, Plasmin. Previous studies suggested that TA may exhibit anticancer activity by blockade of extracellular Plasmin formation. Plasmin-mediated cleavage of the CDCP1 protein may increase its oncogenic functions through several downstream pathways. Results presented herein demonstrate that TA blocks Plasmin-mediated excision of the extracellular domain of the oncoprotein CDCP1. In vitro studies indicate that TA reduces the viability of a broad array of human and murine cancer cell lines, and breast tumor growth studies demonstrate that TA reduces cancer growth in vivo. Based on the ability of TA to mimic Lys and Arg, we hypothesized that TA may perturb multiple processes that involve Lys/Arg-rich protein sequences, and that TA may alter intracellular signaling pathways in addition to blocking extracellular Plasmin production. Indeed, TA-mediated suppression of tumor cell viability is associated with multiple biochemical actions, including inhibition of protein synthesis, reduced activating phosphorylation of STAT3 and S6K1, decreased expression of the MYC oncoprotein, and suppression of Lys acetylation. Further, TA inhibited uptake of Lys and Arg by cancer cells. These findings suggest that TA or TA analogs may serve as lead compounds and inspire the production of new classes of anticancer agents that function by mimicking Lys and Arg.

Evaluation of CDCP1 (CD318) and endoglin (CD105) expression as prognostic markers in acute myeloid leukemia

BACKGROUND: The most commonly used prognostic factors in acute myeloid leukemia (AML) are cytogenetic, molecular, and morphological markers. However, AML prognosis is still unfavorable particularly in adults. So, further reliable markers are urgently needed to improve the risk stratification and treatment decisions. CUB domain-containing protein 1 (CDCP1; CD318) and endoglin (CD105) are new markers correlated with poor prognosis in different solid tumors, but their role in AML prognosis is not fully evaluated. OBJECTIVES: This work aimed to evaluate the prognostic role of CD318 and CD105 in AML and their impact on the outcomes. METHODS: Sixty-five newly diagnosed AML patients were included in this study. CD318 and CD105 expression was assessed by quantitative real-time polymerase chain reaction. Patients were followed up for ∼ 2 years to evaluate the prognostic impact of gene expression on the outcomes. RESULTS: Patients with high CD318 and CD105 showed higher white blood cell (WBC) count, M2 subtype, poor cytogenetic risk, reduced complete remission, and a greater number of deaths compared to low CD318 and CD105. CD318 was correlated with CD105, and both were correlated with WBC count, bone marrow blasts, and peripheral blood blasts. After a follow-up period of up to 24 months, relapse-free survival for high CD318 and CD105 was significantly different (42.1% and 52.6% vs. 64.5% and 58.1% for low CD318 and CD105, respectively). Survival was worse in patients with high CD318 and CD105, as the mean survival time was 13.9 and 13.3 months compared to 24 and 22.7 months in low CD318 and CD105, respectively. CONCLUSIONS: CD318 and CD105 are upregulated in AML patients. Their overexpression was associated with poor response to treatment and poor outcomes. Therefore, CD318 and CD105 can be useful prognostic markers in AML.

Extending the Applicability of In Ovo and Ex Ovo Chicken Chorioallantoic Membrane Assays to Study Cytostatic Activity in Neuroblastoma Cells

Purpose

The chick chorioallantoic membrane (CAM) assay can provide an alternative versatile, cost-effective, and ethically less controversial in vivo model for reliable screening of drugs. In the presented work, we demonstrate that CAM assay (in ovo and ex ovo) can be simply employed to delineate the effects of cisplatin (CDDP) and ellipticine (Elli) on neuroblastoma (Nbl) cells in terms of their growth and metastatic potential.

Methods

The Nbl UKF-NB-4 cell line was established from recurrent bone marrow metastases of high-risk Nbl (stage IV, MYCN amplification, 7q21 gain). Ex ovo and in ovo CAM assays were optimized to evaluate the antimetastatic activity of CDDP and Elli. Immunohistochemistry, qRT-PCR, and DNA isolation were performed.

Results

Ex ovo CAM assay was employed to study whether CDDP and Elli exhibit any inhibitory effects on growth of Nbl xenograft in ex ovo CAM assay. Under the optimal conditions, Elli and CDDP exhibited significant inhibition of the size of the primary tumor. To study the efficiency of CDDP and Elli to inhibit primary Nbl tumor growth, intravasation, and extravasation in the organs, we adapted the in ovo CAM assay protocol. In in ovo CAM assay, both studied compounds (CDDP and Elli) exhibited significant (p < 0.001) inhibitory activity against extravasation to all investigated organs including distal CAM.

Conclusions

Taken together, CAM assay could be a helpful and highly efficient in vivo approach for high-throughput screening of libraries of compounds with expected anticancer activities.

Preclinical Evaluation of a Fluorescent Probe Targeting Receptor CDCP1 for Identification of Ovarian Cancer

Optimal cytoreduction for ovarian cancer is often challenging because of aggressive tumor biology and advanced stage. It is a critical issue since the extent of residual disease after surgery is the key predictor of ovarian cancer patient survival. For a limited number of cancers, fluorescence-guided surgery has emerged as an effective aid for tumor delineation and effective cytoreduction. The intravenously administered fluorescent agent, most commonly indocyanine green (ICG), accumulates preferentially in tumors, which are visualized under a fluorescent light source to aid surgery. Insufficient tumor specificity has limited the broad application of these agents in surgical oncology including for ovarian cancer. In this study, we developed a novel tumor-selective fluorescent agent by chemically linking ICG to mouse monoclonal antibody 10D7 that specifically recognizes an ovarian cancer-enriched cell surface receptor, CUB-domain-containing protein 1 (CDCP1). 10D7^ICG has high affinity for purified recombinant CDCP1 and CDCP1 that is located on the surface of ovarian cancer cells in vitro and in vivo. Our results show that intravenously administered 10D7^ICG accumulates preferentially in ovarian cancer, permitting visualization of xenograft tumors in mice. The data suggest CDCP1 as a rational target for tumor-specific fluorescence-guided surgery for ovarian cancer.

Marine bacterial exopolysaccharide EPS11 inhibits migration and invasion of liver cancer cells by directly targeting collagen I

Many natural polysaccharides have significant anticancer activity with low toxicity, but the complex chemical structures make in-depth studies of the involved mechanisms extremely difficult. The purpose of this study was to investigate the effect of the marine bacterial exopolysaccharide (exopolysaccharide 11 [EPS11]) on liver cancer metastasis to explore the underlying target protein and molecular mechanism. We found that EPS11 significantly suppressed cell adhesion, migration, and invasion in liver cancer cells. Proteomic analysis showed that EPS11 induced downregulation of proteins related to the extracellular matrix–receptor interaction signaling pathway. In addition, the direct pharmacological target of EPS11 was identified as collagen I using cellular thermal shift assays. Surface plasmon resonance and pull-down assays further confirmed the specific binding of EPS11 to collagen I. Moreover, EPS11 was shown to inhibit tumor metastasis by directly modulating collagen I activity via the β1-integrin–mediated signaling pathway. Collectively, our study demonstrated for the first time that collagen I could be a direct pharmacological target of polysaccharide drugs. Moreover, directly targeting collagen I may be a promising strategy for finding novel carbohydrate-based drugs.

Loss of CDCP1 triggers FAK activation in detached prostate cancer cells

A major metastasis suppressing mechanism is the rapid apoptotic death of cancer cells upon detachment from extracellular matrix, a process called anoikis. Focal adhesion kinase (PTK2/FAK) is a key enzyme involved in evasion of anoikis. We show that loss of the Cub-domain containing protein-1 (CDCP1), paradoxically stimulates FAK activation in the detached state of prostate cancer cells. In CDCP1low DU145 and PC3 prostate cancer cells, detachment-activation of FAK occurs through local production of PI(4,5)P2. PI(4,5)P2 is generated by the PIP5K1c-201 splicing isoform of PIP5K1c, which contains a unique SRC phosphorylation site. In the detached state, reduced expression of CDCP1 and an alternative CDCP1-independent SRC activation mechanism triggers PIP5K1c-pY644 phosphorylation by SRC. This causes a switch of Talin binding from β1-integrin to PIP5K1c-pY644 and leads to activation of PIP5K1c-FAK. Reduced CDCP1 expression also inactivates CDK5, a negative regulator of PIP5K1c. Furthermore, immersion of prostate cancer cells in 10% human plasma or fetal bovine serum is required for activation of PIP5K1c-FAK. The PIP5K1c induced detachment-activation of FAK in preclinical models sensitizes CDCP1low prostate cancer cells to FAK inhibitors. In patients, CDCP1High versus CDCP1low circulating tumor cells differ in expression of AR-v7, ONECUT2 and HOXB13 oncogenes and TMPRSS2 and display intra-patient heterogeneity of FAK-pY397 expression. Taken together, CDCP1low and CDCP1high detached prostate cancer cells activate distinct cytoplasmic kinase complexes and targetable transcription factors, which has important therapeutic implications.

Substrate-biased activity-based probes identify proteases that cleave receptor CDCP1

CUB domain-containing protein 1 (CDCP1) is an oncogenic orphan transmembrane receptor and a promising target for the detection and treatment of cancer. Extracellular proteolysis of CDCP1 by poorly defined mechanisms induces pro-metastatic signaling. We describe a new approach for the rapid identification of proteases responsible for key proteolytic events using a substrate-biased activity-based probe (sbABP) that incorporates a substrate cleavage motif grafted onto a peptidyl diphenyl phosphonate warhead for specific target protease capture, isolation and identification. Using a CDCP1-biased probe, we identify urokinase (uPA) as the master regulator of CDCP1 proteolysis, which acts both by directly cleaving CDCP1 and by activating CDCP1-cleaving plasmin. We show that coexpression of uPA and CDCP1 is strongly predictive of poor disease outcome across multiple cancers and demonstrate that uPA-mediated CDCP1 proteolysis promotes metastasis in disease-relevant preclinical in vivo models. These results highlight CDCP1 cleavage as a potential target to disrupt cancer and establish sbABP technology as a new approach to identify disease-relevant proteases.

CDCP1 on Dendritic Cells Contributes to the Development of a Model of Kawasaki Disease

The etiology and pathology of Kawasaki disease (KD) remain elusive. Cub domain-containing protein 1 (CDCP1), a cell-surface protein that confers poor prognosis of patients with certain solid tumors, was recently identified as one of the most significantly upregulated genes in SARS-CoV-2-infected children who developed systemic vasculitis, a hallmark of KD. However, a potential role of CDCP1 in KD has not previously been explored. In this study, we found that CDCP1 knockout (KO) mice exhibited attenuated coronary and aortic vasculitis and decreased serum Candida albicans water-soluble fraction (CAWS)-specific IgM/IgG2a and IL-6 concentrations compared with wild-type mice in an established model of KD induced by CAWS administration. CDCP1 expression was not detectable in cardiomyocytes, cardio fibroblasts, or coronary endothelium, but constitutive expression of CDCP1 was observed on dendritic cells (DCs) and was upregulated by CAWS stimulation. CAWS-induced IL-6 production was significantly reduced in CDCP1 KO DCs, in association with impaired Syk-MAPK signaling pathway activation. These novel findings suggest that CDCP1 might regulate KD development by modulating IL-6 production from DCs via the Syk-MAPK signaling pathway.

CDCP1 promotes compensatory renal growth by integrating Src and Met signaling

CDCP1 promotes HGF-induced compensatory renal growth by focally and temporally integrating Src and Met-STAT3 signaling in lipid rafts.

Compensatory growth of organs after loss of their mass and/or function is controlled by hepatocyte growth factor (HGF), but the underlying regulatory mechanisms remain elusive. Here, we show that CUB domain-containing protein 1 (CDCP1) promotes HGF-induced compensatory renal growth. Using canine kidney cells as a model of renal tubules, we found that HGF-induced temporal up-regulation of Src activity and its scaffold protein, CDCP1, and that the ablation of CDCP1 robustly abrogated HGF-induced phenotypic changes, such as morphological changes and cell growth/proliferation. Mechanistic analyses revealed that up-regulated CDCP1 recruits Src into lipid rafts to activate STAT3 associated with the HGF receptor Met, and activated STAT3 induces the expression of matrix metalloproteinases and mitogenic factors. After unilateral nephrectomy in mice, the Met-STAT3 signaling is transiently up-regulated in the renal tubules of the remaining kidney, whereas CDCP1 ablation attenuates regenerative signaling and significantly suppresses compensatory growth. These findings demonstrate that CDCP1 plays a crucial role in controlling compensatory renal growth by focally and temporally integrating Src and Met signaling.

The CDCP1 Signaling Hub: A Target for Cancer Detection and Therapeutic Intervention

CUB-domain containing protein 1 (CDCP1) is a type I transmembrane glycoprotein that is upregulated in malignancies of the breast, lung, colorectum, ovary, kidney, liver, pancreas, and hematopoietic system. Here, we discuss CDCP1 as an important hub for oncogenic signaling and its key roles in malignant transformation and summarize approaches focused on exploiting it for cancer diagnosis and therapy. Elevated levels of CDCP1 are associated with progressive disease and markedly poorer survival. Predominantly located on the cell surface, CDCP1 lies at the nexus of key tumorigenic and metastatic signaling cascades, including the SRC/PKCδ, PI3K/AKT, WNT, and RAS/ERK axes, the oxidative pentose phosphate pathway, and fatty acid oxidation, making important functional contributions to cancer cell survival and growth, metastasis, and treatment resistance. These findings have stimulated the development of agents that target CDCP1 for detection and treatment of a range of cancers, and results from preclinical models suggest that these approaches could be efficacious and have manageable toxicity profiles.

Neutrophil Elastase Facilitates Tumor Cell Intravasation and Early Metastatic Events

Functional roles of neutrophil elastase (NE) have not been examined in distinct steps of the metastatic cascade. NE, delivered to primary tumors as a purified enzyme or within intact neutrophils or neutrophil granule content, enhanced human tumor cell intravasation and subsequent dissemination via NE-mediated formation of dilated intratumoral vasculature. These effects depended on picomole range of NE activity, sensitive to its natural inhibitor, α1PI. In Elane-negative mice, the lack of NE decreased lung retention of human tumor cells in experimental metastasis. Furthermore, NE was essential for spontaneous metastasis of murine carcinoma cells in a syngeneic orthotopic model of oral cancer. NE also induced tumor cell survival and migration via Src/PI3K-dependent activation of Akt signaling, vital for tumor cell dissemination in vivo. Together, our findings implicate NE, a potent host enzyme specific for first-responding innate immune cells, as directly involved in early metastatic events and a potential target for therapeutic intervention.

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NE enhances human carcinoma cell intravasation and spontaneous metastasis

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NE mediates formation of dilated intratumoral vasculature supporting cell intravasation

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NE-KO mice exhibit decreased lung retention and spontaneous metastasis of tumor cells

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NE induces tumor cell survival and migration via activation of Src/PI3K/Akt pathway

Expression and functional characterization of the CUB domain-containing protein from the triangle sail mussel (Hyriopsis cumingii) in response to pathogenic infection

The complement C1r/C1s, Uegf, and Bmp1 (CUB) domains, which are most exclusively found in extracellular and plasma membrane-related proteins, are involved in various biological processes. In this study, a CUB domain-containing protein (designed as HcCDCP) was cloned and characterized from freshwater pearl mussel (Hyriopsis cumingii). The 2280 bp complete cDNA of the HcCDCP contained a 1002 bp open reading frame, which encoded a protein with 333 amino acids. The predicted HcCDCP protein contained a typical CUB domain and a transmembrane region. The tissue distribution analysis indicated that the HcCDCP was detected in all tissues, and the highest expression was found in hepatopancreas followed by gills. After infection with bacteria (i.e., Staphylococcus aureus and Vibrio parahaemolyticus), virus (white spot syndrome virus) and virus analogs (poly[I:C]), the mRNA level of the HcCDCP was significantly upregulated, suggesting that the HcCDCP might be involved in host immune defense response. The RNA interference revealed that the silencing of the HcCDCP could evidently inhibit the expression levels of lysozyme and tumor necrosis factor. Moreover, the recombinant protein of the CUB domain (rCUB) possessed binding capacity to eight different kinds of bacteria. The polysaccharide binding assay showed that the rCUB specifically bound to lipopolysaccharide, peptidoglycan, and D-mannose. This study provided valuable information for exploring the biological roles of CDCPs in the host defense system of mollusks.

RAC1 induces nuclear alterations through the LINC complex to enhance melanoma invasiveness

RHO GTPases are key regulators of the cytoskeletal architecture, which impact a broad range of biological processes in malignant cells including motility, invasion, and metastasis, thereby affecting tumor progression. One of the constraints during cell migration is the diameter of the pores through which cells pass. In this respect, the size and shape of the nucleus pose a major limitation. Therefore, enhanced nuclear plasticity can promote cell migration. Nuclear morphology is determined in part through the cytoskeleton, which connects to the nucleoskeleton through the Linker of Nucleoskeleton and Cytoskeleton (LINC) complex. Here, we unravel the role of RAC1 as an orchestrator of nuclear morphology in melanoma cells. We demonstrate that activated RAC1 promotes nuclear alterations through its effector PAK1 and the tubulin cytoskeleton, thereby enhancing migration and intravasation of melanoma cells. Disruption of the LINC complex prevented RAC1-induced nuclear alterations and the invasive properties of melanoma cells. Thus, RAC1 induces nuclear morphology alterations through microtubules and the LINC complex to promote an invasive phenotype in melanoma cells.

Biomaterial 3D collagen I gel culture model: A novel approach to investigate tumorigenesis and dormancy of bladder cancer cells induced by tumor microenvironment

The high potential for cancer relapse has emerged as a crucial challenge of human bladder cancer treatment. To date, those stem-like bladder cancer cells (BCSCs) have been considered as seeds that induce frequent tumor recurrence. However, the cell origin of cancer stem cells (CSCs) is still a controversial issue, due in part to the findings that CSCs not only origin from normal stem cells but also converted from differentiated tumor cells. Here, we describe a biomaterial 3D collagen I gel culture system, where non-tumorigenic cells can obtain tumorigenic potential and revert back into CSCs through the integrin α2β1/PI3K/AKT/NF-κB cascade, resulting in the tumorigenesis in bladder tissues. Furthermore, inhibiting this integrin α2β1/PI3K/AKT/NF-κB signal pathways can significantly impair the tumorigenic capacity of CSCs. Simultaneously, in vivo studies demonstrate that IFN-γ secreted by T cells can trigger those CSCs into dormancy through the IDO/Kyn/AHR/P27 cascade, which elicit chemotherapy resistance and cancer relapse. To address the challenges of suppressing bladder tumor growth and preventing tumor reoccurrence, we use IDO and integrin α2β1 signal pathway inhibitors combine with chemotherapeutic agents to awaken dormant bladder CSCs and inhibit their tumorigenic ability as well as effectively eliminate CSCs. The therapeutic approaches we propose provide new insights for eradicating tumors and reducing bladder cancer relapse after therapy.

Microenvironment remodeled by tumor and stromal cells elevates fibroblast-derived COL1A1 and facilitates ovarian cancer metastasis

Wide peritoneal metastasis is the cause of the highest lethality of ovarian cancer in gynecologic malignancies. Ascites play a key role in ovarian cancer metastasis, but involved mechanism is uncertain. Here, we performed a quantitative proteomics of ascites, and found that collagen type I alpha 1 (COL1A1) was notably elevated in ascites from epithelial ovarian cancer patients compared to normal peritoneal fluids, and verified that elevated COL1A1 was mainly originated from fibroblasts. COL1A1 promoted migration and invasion of ovarian cancer cells, but such effects were partially eliminated by COL1A1 antibodies. Intraperitoneally injected COL1A1 accelerated intraperitoneal metastasis of ovarian cancer xenograft in NOD/SCID mice. Further, COL1A1 activated downstream AKT phosphorylation by binding to membrane surface receptor integrin β1 (ITGB1). Knockdown or blockage of ITGB1 reversed COL1A1 enhanced migration and invasion in ovarian cancer cells. Conversely, ovarian cancer ascites and fibrinogen promoted fibroblasts to secrete COL1A1. Elevated fibrinogen in ascites might be associated with increased vascular permeability induced by ovarian cancer. Our findings suggest that microenvironment remodeled by tumor cells and stromal cells promotes fibroblasts to secrete COL1A1 and facilitates the metastasis of ovarian cancer, which may provide a new approach for ovarian cancer therapeutics.

Theranostic Targeting of CUB Domain Containing Protein 1 (CDCP1) in Pancreatic Cancer

PURPOSE

The recent emergence of radioligand therapies for cancer treatment has increased enthusiasm for developing new theranostic strategies coupling both imaging and cytotoxicity in the same entity. In this study, we evaluated whether CUB domain containing protein 1 (CDCP1), a single-pass transmembrane protein highly overexpressed in diverse human cancers, might be a target for cancer theranostics.

EXPERIMENTAL DESIGN

The ectodomain of CDCP1 was targeted using radiolabeled forms of 4A06, a potent and specific recombinant human antibody that we developed. Imaging and antitumor assessment studies were performed in animal models of pancreatic cancer, including two patient-derived xenograft models we developed for this study. For antitumor assessment studies, the endpoints were death due to tumor volume >3,000 mm³ or ≥20% loss in body weight. Specific tracer binding or antitumor effects were assessed with an unpaired, two-tailed Student t test and survival advantages were assessed with a log rank (Mantel-Cox) test. Differences at the 95% confidence level were interpreted to be significant.

RESULTS

⁸⁹Zr-4A06 detected a broad dynamic range of full length or cleaved CDCP1 expression on seven human pancreatic cancer tumors (n = 4/tumor). Treating mice with single or fractionated doses of ¹⁷⁷Lu-4A06 significantly reduced pancreatic cancer tumor volume compared with mice receiving vehicle or unlabeled 4A06 (n = 8; P < 0.01). A single dose of ²²⁵Ac-4A06 also inhibited tumor growth, although the effect was less profound compared with ¹⁷⁷Lu-4A06 (n = 8; P < 0.01). A significant survival advantage was imparted by ²²⁵Ac-4A06 (HR = 2.56; P < 0.05).

CONCLUSIONS

These data establish that CDCP1 can be exploited for theranostics, a finding with widespread implications given its breadth of overexpression in cancer.

Effective targeting of intact and proteolysed CDCP1 for imaging and treatment of pancreatic ductal adenocarcinoma

Background: CUB domain-containing protein 1 (CDCP1) is a cell surface receptor regulating key signalling pathways in malignant cells. CDCP1 has been proposed as a molecular target to abrogate oncogenic signalling pathways and specifically deliver anti-cancer agents to tumors. However, the development of CDCP1-targeting agents has been questioned by its frequent proteolytic processing which was thought to result in shedding of the CDCP1 extracellular domain limiting its targetability. In this study, we investigated the relevance of targeting CDCP1 in the context of pancreatic ductal adenocarcinoma (PDAC) and assess the impact of CDCP1 proteolysis on the effectiveness of CDCP1 targeting agents. Methods: The involvement of CDCP1 in PDAC progression was assessed by association analysis in several PDAC cohorts and the proteolytic processing of CDCP1 was evaluated in PDAC cell lines and patient-derived cells. The consequences of CDCP1 proteolysis on its targetability in PDAC cells was assessed using immunoprecipitation, immunostaining and biochemical assays. The involvement of CDCP1 in PDAC progression was examined by loss-of-function in vitro and in vivo experiments employing PDAC cells expressing intact or cleaved CDCP1. Finally, we generated antibody-based imaging and therapeutic agents targeting CDCP1 to demonstrate the feasibility of targeting this receptor for detection and treatment of PDAC tumors. Results: High CDCP1 expression in PDAC is significantly associated with poorer patient survival. In PDAC cells proteolysis of CDCP1 does not always result in the shedding of CDCP1-extracellular domain which can interact with membrane-bound CDCP1 allowing signal transduction between the different CDCP1-fragments. Targeting CDCP1 impairs PDAC cell functions and PDAC tumor growth independently of CDCP1 cleavage status. A CDCP1-targeting antibody is highly effective at delivering imaging radionuclides and cytotoxins to PDAC cells allowing specific detection of tumors by PET/CT imaging and superior anti-tumor effects compared to gemcitabine in in vivo models. Conclusion: Independent of its cleavage status, CDCP1 exerts oncogenic functions in PDAC and has significant potential to be targeted for improved radiological staging and treatment of this cancer. Its elevated expression by most PDAC tumors and lack of expression by normal pancreas and other major organs, suggest that targeting CDCP1 could benefit a significant proportion of PDAC patients. These data support the further development of CDCP1-targeting agents as personalizable tools for effective imaging and treatment of PDAC.

Comparing Metastatic Clear Cell Renal Cell Carcinoma Model Established in Mouse Kidney and on Chicken Chorioallantoic Membrane

Metastatic clear cell renal cell carcinoma (ccRCC) is the most common subtype of kidney cancer. Localized ccRCC has a favorable surgical outcome. However, one third of ccRCC patients will develop metastases to the lung, which is related to a very poor outcome for patients. Unfortunately, no therapy is available for this deadly stage, because the molecular mechanism of metastasis remains unknown. It has been known for 25 years that the loss of function of the von Hippel-Lindau (VHL) tumor suppressor gene is pathognomonic of ccRCC. However, no clinically relevant transgenic mouse model of ccRCC has been generated. The purpose of this protocol is to introduce and compare two newly established animal models for metastatic ccRCC. The first is renal implantation in the mouse model. In our laboratory, the CRISPR gene editing system was utilized to knock out the VHL gene in several RCC cell lines. Orthotopic implantation of heterogeneous ccRCC populations to the renal capsule created novel ccRCC models that develop robust lung metastases in immunocompetent mice. The second model is the chicken chorioallantoic membrane (CAM) system. In comparison to the mouse model, this model is more time, labor, and cost-efficient. This model also supported robust tumor formation and intravasation. Due to the short 10 day period of tumor growth in CAM, no overt metastasis was observed by immunohistochemistry (IHC) in the collected embryo tissues. However, when tumor growth was extended by two weeks in the hatched chicken, micrometastatic ccRCC lesions were observed by IHC in the lungs. These two novel preclinical models will be useful to further study the molecular mechanism behind metastasis, as well as to establish new, patient-derived xenografts (PDXs) toward the development of novel treatments for metastatic ccRCC.

Identification of CD318 (CDCP1) as novel prognostic marker in AML

Genetic and morphological markers are well-established prognostic factors in acute myeloid leukemia (AML). However, further reliable markers are urgently needed to improve risk stratification in AML. CD318 (CDCP1) is a transmembrane protein which in solid tumors promotes formation of metastasis and correlates with poor survival. Despite its broad expression on hematological precursor cells, its prognostic significance in hematological malignancies so far remains unclear. Here, we evaluated the role of CD318 as novel prognostic marker in AML by immunophenotyping of leukemic blasts. Flow cytometric evaluation of CD318 on leukemic cells in 70 AML patients revealed a substantial expression in 40/70 (57%) of all cases. CD318 surface levels were significantly correlated with overall survival in patients receiving anthracycline-based induction therapy or best available alternative therapy. Using receiver-operating characteristics, we established a cut-off value to define CD318^lo and CD318^hi expression in both cohorts. Notably, high CD318 expression correlated inversely as prognostic marker in both treatment cohorts: as poor prognostic marker in patients receiving intense therapy, whereas upon palliative care it correlated with better outcome. In conclusion, FACS-based determination of CD318 expression may serve as novel prognostic factor depending on implemented therapy in AML patients.

Anti-CDCP1 immuno-conjugates for detection and inhibition of ovarian cancer

CUB-domain containing protein 1 (CDCP1) is a cancer associated cell surface protein that amplifies pro-tumorigenic signalling by other receptors including EGFR and HER2. Its potential as a cancer target is supported by studies showing that anti-CDCP1 antibodies inhibit cell migration and survival in vitro, and tumor growth and metastasis in vivo. Here we characterize two anti-CDCP1 antibodies, focusing on immuno-conjugates of one of these as a tool to detect and inhibit ovarian cancer. Methods: A panel of ovarian cancer cell lines was examined for cell surface expression of CDCP1 and loss of expression induced by anti-CDCP1 antibodies 10D7 and 41-2 using flow cytometry and Western blot analysis. Surface plasmon resonance analysis and examination of truncation mutants was used to analyse the binding properties of the antibodies for CDCP1. Live-cell spinning-disk confocal microscopy of GFP-tagged CDCP1 was used to track internalization and intracellular trafficking of CDCP1/antibody complexes. In vivo, zirconium 89-labelled 10D7 was detected by positron-emission tomography imaging, of an ovarian cancer patient-derived xenograft grown intraperitoneally in mice. The efficacy of cytotoxin-conjugated 10D7 was examined against ovarian cancer cells in vitro and in vivo. Results: Our data indicate that each antibody binds with high affinity to the extracellular domain of CDCP1 causing rapid internalization of the receptor/antibody complex and degradation of CDCP1 via processes mediated by the kinase Src. Highlighting the potential clinical utility of CDCP1, positron-emission tomography imaging, using zirconium 89-labelled 10D7, was able to detect subcutaneous and intraperitoneal xenograft ovarian cancers in mice, including small (diameter <3 mm) tumor deposits of an ovarian cancer patient-derived xenograft grown intraperitoneally in mice. Furthermore, cytotoxin-conjugated 10D7 was effective at inhibiting growth of CDCP1-expressing ovarian cancer cells in vitro and in vivo. Conclusions: These data demonstrate that CDCP1 internalizing antibodies have potential for killing and detection of CDCP1 expressing ovarian cancer cells.

Increased intracellular Cl- concentration by activating FAK promotes airway epithelial BEAS-2B cells proliferation and wound healing

An increase in intracellular Cl^- concentration ([Cl^-]_i) may be a general response of airway epithelial cells to various stimuli and may participate in some basic cellular functions. However, whether the basic functional activities of cells, such as proliferation and wound healing, are related to Cl^- activities remains unclear. This study aimed to investigate the effects and potential mechanisms of [Cl^-]_i on the proliferation and wound healing ability of airway epithelial BEAS-2B cells. BEAS-2B cells were treated with four Cl^- channel inhibitors (T16Ainh-A01, CFTRinh-172, CaCCinh-A01, and IAA-94), and the Cl^- fluorescence probe N-(ethoxycarbonylmethyl)-6-methoxyquinolinium bromide was used. Results showed that all Cl^- channel inhibitors could increase [Cl^-]_i in BEAS-2B cells. The increased [Cl^-]_i induced by Cl^- channel inhibitors or clamping [Cl^-]_i at high levels enhanced the phosphorylation of focal adhesion kinase (FAK) and subsequently promoted the proliferation and wound healing ability of BEAS-2B cells. By contrast, the FAK inhibitor PF573228 abrogated these effects induced by the increased [Cl^-]_i. FAK also activated the PI3K/AKT signaling pathway. In conclusion, increased [Cl^-]_i promotes the proliferation and wound healing ability of BEAS-2B cells by activating FAK to activate the PI3K/AKT signaling pathway. Intracellular Cl^- may act as a signaling molecule to regulate the proliferation and wound healing ability of airway epithelial cells.

CUB domain-containing protein 1 (CDCP1) binds transforming growth factor beta family members and increase TGF-β1 signaling pathway

CUB domains are most exclusively found in secreted proteins and in a few transmembrane proteins. These domains are approximately 110 amino acids long and have four conserved cysteines that form a β-sandwich fold. CUB domains proteins are involved in a wide range of biological functions. We have shown that CUB domains from Tolloid/BMP1 can bind BMP4 and block BMP signaling in the developing frog embryo. CUB domain-containing protein 1 (CDCP1) is one of the few transmembrane glycoprotein that contains three extracellular CUB domains and regulates anchorage-independent growth and cancer cell migration through activation of Src kinases. In the extracellular space, only a few proteins were found to interact with CDCP1 and at the moment no ligand was found. We demonstrate by using real time protein interaction on BIAcore chip that CDCP1 CUB domains bind directly to TGF-β1 and BMP4. CDCP1 enhances TGF-β1 signaling reporter activity and phosphorylated Smad2 levels but does not modulate BMP signaling pathway. CDCP1 actions on TGF-β/Smad2 signaling are dependent on Smad2 and TGFRI and do not require Src or PKCδ binding. Our findings uncover a new co-receptor for TGF-β1 and bring up new questions on whether CDCP1 cooperates with TGF-β1 to promote cancer progression.

Gene Editing of α6 Integrin Inhibits Muscle Invasive Networks and Increases Cell-Cell Biophysical Properties in Prostate Cancer

Human prostate cancer confined to the gland is indolent (low-risk), but tumors outside the capsule are aggressive (high-risk). Extracapsular extension requires invasion within and through a smooth muscle-structured environment. Because integrins respond to biomechanical cues, we used a gene editing approach to determine if a specific region of laminin-binding α6β1 integrin was required for smooth muscle invasion both in vitro and in vivo. Human tissue specimens showed prostate cancer invasion through smooth muscle and tumor coexpression of α6 integrin and E-cadherin in a cell-cell location and α6 integrin in a cell-extracellular matrix (ECM) distribution. Prostate cancer cells expressing α6 integrin (DU145 α6WT) produced a 3D invasive network on laminin-containing Matrigel and invaded into smooth muscle both in vitro and in vivo. In contrast, cells without α6 integrin (DU145 α6KO) and cells expressing an integrin mutant (DU145 α6AA) did not produce invasive networks, could not invade muscle both in vitro and in vivo, and surprisingly formed 3D cohesive clusters. Using electric cell-substrate impedance testing, cohesive clusters had up to a 30-fold increase in normalized resistance at 400 Hz (cell-cell impedance) as compared with the DU145 α6WT cells. In contrast, measurements at 40,000 Hz (cell-ECM coverage) showed that DU145 α6AA cells were two-fold decreased in normalized resistance and were defective in restoring resistance after a 1 μmol/L S1P challenge as compared with the DU145 α6WT cells. The results suggest that gene editing of a specific α6 integrin extracellular region, not required for normal tissue function, can generate a new biophysical cancer phenotype unable to invade the muscle, presenting a new therapeutic strategy for metastasis prevention in prostate cancer. SIGNIFICANCE: This study shows an innovative strategy to block prostate cancer metastasis and invasion in the muscle through gene editing of a specific α6 integrin extracellular region.

Substrate stiffness directs diverging vascular fates

Embryonic stem cells (ESC) are excellent cell culture systems for elucidating developmental signals that may be part of the stem cell niche. Although stem cells are traditionally induced using predominately soluble signals, the mechanical environment of the niche can also play a role in directing cells towards differential cell lineages. Interested in diverging vascular fates, we set out to examine to what extent mechanical signaling played a role in endothelial cell and/or smooth muscle fate. Using chemically-defined staged vascular differentiation methods, vascular progenitor cells (VPC) fate was examined on single stiffness polyacrylamide hydrogels of 10 kPa, 40 kPa and >0.1 GPa. Emergence of vascular cell populations aligned with corresponding hydrogel stiffness: EC-lineages favoring the softer material and SMC lineages favoring the stiffest material. Statistical significance was observed on both cell lines on almost all days. Transcriptome analysis indicated that the populations on the varying stiffness emerge in distinct categories. Lastly, blocking studies show that αvβ1, and not αvβ6, activation mediates stiffness-directed vascular differentiation. Overall, these studies indicate that softer materials direct VPCs into a more EC-like fate compared to stiffer materials. STATEMENT OF SIGNIFICANCE: Although stem cells are traditionally induced using predominately soluble signals, the mechanical environment of the niche also plays a role in directing cell fate. Several studies have examined the stiffness-induced cell fate from mesenchymal stem cells (MSCs) and undifferentiated embryonic stem cells (ESCs). This is the first study that rigorously examines the role of matrix stiffness in diverging vascular fates from a purified population of vascular progenitor cells (VPCs). We show that the emergence of endothelial cell (EC) versus smooth muscle cell (SMC) populations corresponds with hydrogel stiffness: EC-lineages favoring the softness material and SMC lineages favoring the stiffest material, and that αvβ1 activation mediates this stiffness-directed vascular differentiation.

H19 suppresses the growth of hepatoblastoma cells by promoting their apoptosis via the signaling pathways of miR-675/FADD and miR-138/PTK2

BACKGROUND

The objective of this study was to clarify the molecular pathways involved in hepatitis B virus (HBV)-induced hepatoblastoma.

METHOD

The expression of factors in different signaling pathways (H19, miR-675, miR-138, protein tyrosine kinase 2 [PTK2], fas-associated death domain [FADD], hypoxia-inducible factor 1-alpha [HIFIA], focal adhesion kinase [FAK], caspase-8, and caspase-3) was compared between HBV (+) and HBV (-) groups using quantitative real-time polymerase chain reaction and Western blot analysis. Subsequently, immunohistochemistry (IHC) and TdT-mediated dUTP Nick-End Labeling (TUNEL) assays were used to verify the expression of above proteins in HBV (+) and HBV (-) groups. Computational analysis was conducted to predict the target genes of miR-675 and miR-138, whose regulatory relationships were then clarified using luciferase assays and cell transfection studies.

RESULT

The expression of H19, miR-675, PTK2, HIFIA, and FAK was increased in the HBV (+) group, while the expression of miR-138, FADD, caspase-8, and caspase-3 was decreased in the HBV (+) group. FADD and PTK2 were identified as target genes of miR-675 and miR-138, respectively. In addition, miR-675 was upregulated while miR-138 was downregulated by X protein (HBx).

CONCLUSION

In summary, the results of this study revealed the molecular pathways involved in HBV-induced hepatoblastoma. In the presence of HBV, HBX upregulated the expression of H19 through HIFIA. Consecutively, overexpressed H19 upregulated the expression of PTK2 via targeting miR-138 and downregulated the expression of FADD via targeting miR-675. Finally, increased expression of PTK2 and reduced expression of FADD both led to the inhibition of cell apoptosis, thus promoting the tumorigenesis of hepatoblastoma.

Origins and clinical relevance of proteoforms in pediatric malignancies

INTRODUCTION

Cancer changes the proteome in complex ways that reach well beyond simple changes in protein abundance. Genomic and transcriptional variations and post-translational protein modification create functional variants of a protein, known as proteoforms. Childhood cancers have fewer genomic alterations but show equally dramatic phenotypic changes as malignant cells in adults. Therefore, unraveling the complexities of the proteome is even more important in pediatric malignancies. Areas covered: In this review, the biological origins of proteoforms and technological advancements in the study of proteoforms are discussed. Particular emphasis is given to their implication in childhood malignancies and the critical role of cancer-specific proteoforms for the next generation of cancer therapies and diagnostics. Expert opinion: Recent advancements in technology have led to a better understanding of the underlying mechanisms of tumorigenesis. This has been critical for the development of more effective and less harmful treatments that are based on direct targeting of altered proteins and deregulated pathways. As proteome coverage and the ability to detect complex proteoforms increase, the most need for change is in data compilation and database availability to mediate high-level data analysis and allow for better functional annotation of proteoforms.