TACE cleavage of proamphiregulin regulates GPCR-induced proliferation and motility of cancer cells

Lysophospholipase D activity on oral mucosa cells in whole mixed human saliva involves in production of bioactive lysophosphatidic acid from lysophosphatidylcholine

We reported that lysophosphatidic acid (LPA) is present at 0.8 μM in mixed human saliva (MS). In this study, we examined the distribution, origin, and enzymatic generation pathways of LPA in MS. LPA was distributed in the medium and cell pellet fraction; a true level of soluble LPA in MS was about 150 nM. The soluble LPA was assumed to be generated by ecto-type lysophospholipase D on exfoliated cells in MS from LPC that originated mainly from the major salivary gland saliva. Our results with the albumin-back extraction procedures suggest that a significant pool of LPA is kept in the outer layer of the plasma membranes of detached oral mucosal cells. Such pool of LPA may contribute to wound healing in upper digestive organs including oral cavity. We obtained evidence that the choline-producing activity in MS was mainly due to Ca2+-activated lysophospholipase D activity of glycerophosphodiesterase 7.

In vitro evidence for the potential of EGFR inhibitors to decrease the TGF-β1-induced dispersal of circulating tumour cell clusters mediated by EGFR overexpression

Most cancer-related deaths are due to the spread of tumour cells throughout the body-a process known as metastasis. While in the vasculature, these cells are referred to as circulating tumour cells (CTCs) and can be found as either single cells or clusters of cells (often including platelets), with the latter having the highest metastatic potential. However, the biology of CTC clusters is poorly understood, and there are no therapies that specifically target them. We previously developed an in vitro model system for CTC clusters and proposed a new extravasation model that involves cluster dissociation, adherence, and single-cell invasion in response to TGF-β1 released by platelets. Here, we investigated TGF-β1-induced gene expression changes in this model, focusing on genes for which targeted drugs are available. In addition to the upregulation of the TGF-β1 signalling pathway, we found that (i) genes in the EGF/EGFR pathway, including those coding for EGFR and several EGFR ligands, were also induced, and (ii) Erlotinib and Osimertinib, two therapeutic EGFR/tyrosine kinase inhibitors, decreased the TGF-β1-induced adherence and invasion of the CTC cluster-like line despite the line expressing wild-type EGFR. Overall, we suggest that EGFR inhibitors have the potential to decrease the dispersal of CTC clusters that respond to TGF-β1 and overexpress EGFR (irrespective of its status) and thus could improve patient survival.

Developing theragnostics for Alzheimer's disease: Insights from cancer treatment

The prevalence of Alzheimer's disease (AD) and its associated economic and societal burdens are on the rise, but there are no curative treatments for AD. Interestingly, this neurodegenerative disease shares several biological and pathophysiological features with cancer, including cell-cycle dysregulation, angiogenesis, mitochondrial dysfunction, protein misfolding, and DNA damage. However, the genetic factors contributing to the overlap in biological processes between cancer and AD have not been actively studied. In this review, we discuss the shared biological features of cancer and AD, the molecular targets of anticancer drugs, and therapeutic approaches. First, we outline the common biological features of cancer and AD. Second, we describe several anticancer drugs, their molecular targets, and their effects on AD pathology. Finally, we discuss how protein-protein interactions (PPIs), receptor inhibition, immunotherapy, and gene therapy can be exploited for the cure and management of both cancer and AD. Collectively, this review provides insights for the development of AD theragnostics based on cancer drugs and molecular targets.

Role of iRhom2 in Olfaction: Implications for Odorant Receptor Regulation and Activity-Dependent Adaptation

The cell surface metalloprotease ADAM17 (a disintegrin and metalloprotease 17) and its binding partners iRhom2 and iRhom1 (inactive Rhomboid-like proteins 1 and 2) modulate cell-cell interactions by mediating the release of membrane proteins such as TNFα (Tumor necrosis factor α) and EGFR (Epidermal growth factor receptor) ligands from the cell surface. Most cell types express both iRhoms, though myeloid cells exclusively express iRhom2, and iRhom1 is the main iRhom in the mouse brain. Here, we report that iRhom2 is uniquely expressed in olfactory sensory neurons (OSNs), highly specialized cells expressing one olfactory receptor (OR) from a repertoire of more than a thousand OR genes in mice. iRhom2-/- mice had no evident morphological defects in the olfactory epithelium (OE), yet RNAseq analysis revealed differential expression of a small subset of ORs. Notably, while the majority of ORs remain unaffected in iRhom2-/- OE, OSNs expressing ORs that are enriched in iRhom2-/- OE showed fewer gene expression changes upon odor environmental changes than the majority of OSNs. Moreover, we discovered an inverse correlation between the expression of iRhom2 compared to OSN activity genes and that odor exposure negatively regulates iRhom2 expression. Given that ORs are specialized G-protein coupled receptors (GPCRs) and many GPCRs activate iRhom2/ADAM17, we investigated if ORs could activate iRhom2/ADAM17. Activation of an olfactory receptor that is ectopically expressed in keratinocytes (OR2AT4) by its agonist Sandalore leads to ERK1/2 phosphorylation, likely via an iRhom2/ADAM17-dependent pathway. Taken together, these findings point to a mechanism by which odor stimulation of OSNs activates iRhom2/ADAM17 catalytic activity, resulting in downstream transcriptional changes to the OR repertoire and activity genes, and driving a negative feedback loop to downregulate iRhom2 expression.

CD133 Stimulates Cell Proliferation via the Upregulation of Amphiregulin in Melanoma

CD133, a cancer stem cell (CSC) marker in tumors, including melanoma, is associated with tumor recurrence, chemoresistance, and metastasis. Patient-derived melanoma cell lines were transduced with a Tet-on vector expressing CD133, generating doxycycline (Dox)-inducible cell lines. Cells were exposed to Dox for 24 h to induce CD133 expression, followed by RNA-seq and bioinformatic analyses, revealing genes and pathways that are significantly up- or downregulated by CD133. The most significantly upregulated gene after CD133 was amphiregulin (AREG), validated by qRT-PCR and immunoblot analyses. Induced CD133 expression significantly increased cell growth, percentage of cells in S-phase, BrdU incorporation into nascent DNA, and PCNA levels, indicating that CD133 stimulates cell proliferation. CD133 induction also activated EGFR and the MAPK pathway. Potential mechanisms highlighting the role(s) of CD133 and AREG in melanoma CSC were further delineated using AREG/EGFR inhibitors or siRNA knockdown of AREG mRNA. Treatment with the EGFR inhibitor gefitinib blocked CD133-induced cell growth increase and MAPK pathway activation. Importantly, siRNA knockdown of AREG reversed the stimulatory effects of CD133 on cell growth, indicating that AREG mediates the effects of CD133 on cell proliferation, thus serving as an attractive target for novel combinatorial therapeutics in melanoma and cancers with overexpression of both CD133 and AREG.

New insight into the role of the ADAM protease family in breast carcinoma progression

Protease and adhesion molecules play a very emphasized role in the occurrence or progression of metastasis in many types of cancers. In this context, a molecule that contains both protease and adhesion functions play a crucial role in metastasis. ADAMs (a disintegrin and metalloprotease) are molecules with this special characteristic. Recently, a lot of attention has been attracted to various ADAM molecules and researchers have tried to elucidate the role of ADAMs in breast cancer occurrence and progression. Disrupting ADAMs protease and adhesion capabilities can lead to the discovery of worthy therapeutic targets in breast cancer treatment. In this review, we intend to discuss the mechanism of action of various ADAM molecules, their relation to pathogenic processes of breast cancer, and their potential as possible targets for breast cancer treatment.

New insights into RAS in head and neck cancer

RAS genes are known to be dysregulated in cancer for several decades, and substantial effort has been dedicated to develop agents that reduce RAS expression or block RAS activation. The recent introduction of RAS inhibitors for cancer patients highlights the importance of comprehending RAS alterations in head and neck cancer (HNC). In this regard, we examine the published findings on RAS alterations and pathway activations in HNC, and summarize their role in HNC initiation, progression, and metastasis. Specifically, we focus on the intrinsic role of mutated-RAS on tumor cell signaling and its extrinsic role in determining tumor-microenvironment (TME) heterogeneity, including promoting angiogenesis and enhancing immune escape. Lastly, we summarize the intrinsic and extrinsic role of RAS alterations on therapy resistance to outline the potential of targeting RAS using a single agent or in combination with other therapeutic agents for HNC patients with RAS-activated tumors.

The ADAM17 sheddase complex regulator iTAP/Frmd8 modulates inflammation and tumor growth

The metalloprotease ADAM17 is a sheddase of key molecules, including TNF and epidermal growth factor receptor ligands. ADAM17 exists within an assemblage, the "sheddase complex," containing a rhomboid pseudoprotease (iRhom1 or iRhom2). iRhoms control multiple aspects of ADAM17 biology. The FERM domain-containing protein iTAP/Frmd8 is an iRhom-binding protein that prevents the precocious shunting of ADAM17 and iRhom2 to lysosomes and their consequent degradation. As pathophysiological role(s) of iTAP/Frmd8 have not been addressed, we characterized the impact of iTAP/Frmd8 loss on ADAM17-associated phenotypes in mice. We show that iTAP/Frmd8 KO mice exhibit defects in inflammatory and intestinal epithelial barrier repair functions, but not the collateral defects associated with global ADAM17 loss. Furthermore, we show that iTAP/Frmd8 regulates cancer cell growth in a cell-autonomous manner and by modulating the tumor microenvironment. Our work suggests that pharmacological intervention at the level of iTAP/Frmd8 may be beneficial to target ADAM17 activity in specific compartments during chronic inflammatory diseases or cancer, while avoiding the collateral impact on the vital functions associated with the widespread inhibition of ADAM17.

Novel insight on GRP/GRPR axis in diseases

The gastrin-releasing peptide receptor (GRPR), a member of the G protein-coupled receptors (GPCRs), binds to ligands such as gastrin-releasing peptide (GRP) and plays a variety of biological roles. GRP/GRPR signalling is involved in the pathophysiological processes of many diseases, including inflammatory diseases, cardiovascular diseases, neurological diseases, and various cancers. In the immune system, the unique function of GRP/GRPR in neutrophil chemotaxis suggests that GRPR can be directly stimulated through GRP-mediated neutrophils to activate selective signalling pathways, such as PI3K, PKC, and MAPK, and participate in the occurrence and development of inflammation-related diseases. In the cardiovascular system, GRP increases intercellular adhesion molecule 1 (ICAM-1) and induces vascular cell adhesion molecule-1 (VCAM-1). GRP activates ERK1/2, MAPK, and AKT, leading to cardiovascular diseases, including myocardial infarction. Central nervous system signal transduction mediated by the GRP/GRPR axis plays a vital role in emotional responses, social interaction, and memory. The GRP/GRPR axis is elevated in various cancers, including lung, cervical, colorectal, renal cell, and head and neck squamous cell carcinomas. GRP is a mitogen in a variety of tumour cell lines. Its precursor, pro-gastrin-releasing peptide (ProGRP), may play an important role as an emerging tumour marker in early tumour diagnosis. GPCRs serve as therapeutic targets for drug development, but their function in each disease remains unclear, and their involvement in disease progression has not been well explored or summarised. This review lays out the above mentioned pathophysiological processes based on previous research conclusions. The GRP/GRPR axis may be a potential target for treating multiple diseases, and the study of this signalling axis is particularly important.

Lysophosphatidic acid suppresses apoptosis of high-grade serous ovarian cancer cells by inducing autophagy activity and promotes cell-cycle progression via EGFR-PI3K/Aurora-AThr288-geminin dual signaling pathways

Lysophosphatidic acid (LPA) and geminin are overexpressed in ovarian cancer, and increasing evidence supports their contribution to ovarian tumor development. Here, we reveal that geminin depletion induces autophagy suppression and enhances reactive oxygen species (ROS) production and apoptosis of high-grade serous ovarian cancer (HGSOC) cells. Bioinformatics analysis and pharmacological inhibition studies confirm that LPA activates geminin expression in the early S phase in HGSOC cells via the LPAR1/3/MMPs/EGFR/PI3K/mTOR pathway. Furthermore, LPA phosphorylates Aurora-A kinase on Thr288 through EGFR transactivation, and this event potentiates additional geminin stabilization. In turn, overexpressed and stabilized geminin regulates DNA replication, cell-cycle progression, and cell proliferation of HGSOC cells. Our data provide potential targets for enhancing the clinical benefit of HGSOC precision medicine.

ADAM10 mediates shedding of carbonic anhydrase IX ectodomain non‑redundantly to ADAM17

Carbonic anhydrase IX (CA IX) is a transmembrane enzyme participating in adaptive responses of tumors to hypoxia and acidosis. CA IX regulates pH, facilitates metabolic reprogramming, and supports migration, invasion and metastasis of cancer cells. Extracellular domain (ECD) of CA IX can be shed to medium and body fluids by a disintegrin and metalloproteinase (ADAM) 17. Here we show for the first time that CA IX ECD shedding can be also executed by ADAM10, a close relative of ADAM17, via an overlapping cleavage site in the stalk region of CA IX connecting its exofacial catalytic site with the transmembrane region. This finding is supported by biochemical evidence using recombinant human ADAM10 protein, colocalization of ADAM10 with CA IX, ectopic expression of a dominant‑negative mutant of ADAM10 and RNA interference‑mediated suppression of ADAM10. Induction of the CA IX ECD cleavage with ADAM17 and/or ADAM10 activators revealed their additive effect. Similarly, additive effect was observed with an ADAM17‑inhibiting antibody and an ADAM10‑preferential inhibitor GI254023X. These data indicated that ADAM10 is a CA IX sheddase acting on CA IX non‑redundantly to ADAM17.

Pan-cancer distribution of cleaved cell-surface Amphiregulin, the target of the GMF-1A3 antibody drug conjugate

Amphiregulin is a transmembrane protein which, when cleaved by the TACE/ADAM17 protease, releases a soluble epidermal growth factor receptor ligand domain that promotes proliferation of normal and malignant cells. We previously described a rabbit monoclonal antibody, GMF-1A3, that selectively recognizes the cell-associated cleaved amphiregulin epitope. Antibody-drug conjugates had anti-tumor activity against human breast cancer xenografts. Several tumor types express amphiregulin, but evidence for a functional requirement for amphiregulin in these malignancies is limited. By directly evaluating amphiregulin cleavage with immunohistochemistry, GMF-1A3 provides a more direct measure of amphiregulin activity. Using 370 specimens from 10 tumor types (as well as normal controls), we demonstrate that cleaved amphiregulin is widely expressed in solid tumors and is especially common (> 50% of cases) in breast, prostate, liver and lung cancer. As a potential companion diagnostic for this antibody-drug conjugate, this assay allows identification of tumors with high levels of the cleaved amphiregulin target.

Lysophosphatidylserine Induces MUC5AC Production via the Feedforward Regulation of the TACE-EGFR-ERK Pathway in Airway Epithelial Cells in a Receptor-Independent Manner

Lysophosphatidylserine (LysoPS) is an amphipathic lysophospholipid that mediates a broad spectrum of inflammatory responses through a poorly characterized mechanism. Because LysoPS levels can rise in a variety of pathological conditions, we sought to investigate LysoPS's potential role in airway epithelial cells that actively participate in lung homeostasis. Here, we report a previously unappreciated function of LysoPS in production of a mucin component, MUC5AC, in the airway epithelial cells. LysoPS stimulated lung epithelial cells to produce MUC5AC via signaling pathways involving TACE, EGFR, and ERK. Specifically, LysoPS- dependent biphasic activation of ERK resulted in TGF-α secretion and strong EGFR phosphorylation leading to MUC5AC production. Collectively, LysoPS induces the expression of MUC5AC via a feedback loop composed of proligand synthesis and its proteolysis by TACE and following autocrine EGFR activation. To our surprise, we were not able to find a role of GPCRs and TLR2, known LyoPS receptors in LysoPS-induced MUC5AC production in airway epithelial cells, suggesting a potential receptor-independent action of LysoPS during inflammation. This study provides new insight into the potential function and mechanism of LysoPS as an emerging lipid mediator in airway inflammation.

Oncogenic KRAS promotes growth of lung cancer cells expressing SLC3A2-NRG1 fusion via ADAM17-mediated shedding of NRG1

We previously found the SLC3A2-NRG1 (S-N) fusion gene in a lung adenocarcinoma specimen without known driver mutations and validated this in 59 invasive mucinous adenocarcinoma (IMA) samples. Interestingly, KRAS mutation coexisted (62.5%) in 10 out of 16 NRG1 fusions. In this study, we examined the role of mutant KRAS in regulating the S-N fusion protein in KRAS mutant (H358) and wild-type (Calu-3) cells. KRAS mutation-mediated increase in MEK1/2 and ERK1/2 activity enhanced disintegrin and metalloproteinase (ADAM)17 activity, which increased the shedding of NRG1 from the S-N fusion protein. The cleavage of NRG1 also increased the phosphorylation of ERBB2-ERBB3 heterocomplex receptors and their downstream signalling pathways, including PI3K/Akt/mTOR, even under activated KRAS mutation signalling. The concurrence of S-N fusion and KRAS mutation synergistically increased cell proliferation, colony formation, tumour growth, and the cells' resistance to EGFR kinase inhibitors more than KRAS mutation alone. Targeted inhibition of MEK1/2, and ADAM17 significantly induced apoptosis singly and when combined with each mutation singly or with chemotherapy in both the concurrent KRAS mutant and S-N fusion xenograft and lung orthotopic models. Taken together, this is the first study to report that KRAS mutation increased NRG1 cleavage from the S-N fusion protein through ADAM17, thereby enhancing the Ras/Raf/MEK/ERK and ERBB/PI3K/Akt/mTOR pathways. Moreover, the coexistence of KRAS mutant and S-N fusion in lung tumours renders them vulnerable to MEK1/2 and/or ADAM17 inhibitors, at least in part, due to their dependency on the strong positive loop between KRAS mutation and S-N fusion.

Anti-tumor efficacy of an MMAE-conjugated antibody targeting cell surface TACE/ADAM17-cleaved Amphiregulin in breast cancer

Background

The Epidermal Growth Factor Receptor (EGFR) ligand, Amphiregulin (AREG), is a key proliferative effector of estrogen receptor signaling in breast cancer and also plays a role in other malignancies. AREG is a single-pass transmembrane protein proteolytically processed by TACE/ADAM17 to release the soluble EGFR ligand, leaving a residual transmembrane stalk that is subsequently internalized.

Methods

Using phage display, we identified antibodies that selectively recognize the residual transmembrane stalk of cleaved AREG. Conjugation with fluorescence labels and monomethyl auristatin E (MMAE) was used to study their intracellular trafficking and anti-cancer effects, respectively.

Results

We report the development of an antibody-drug conjugate (ADC), GMF-1A3-MMAE, targeting an AREG neo-epitope revealed following ADAM17-mediated cleavage. The antibody does not interact with uncleaved AREG, providing a novel means of targeting cells with high rates of AREG shedding. Using fluorescent dye conjugation, we demonstrated that the antibody is internalized by cancer cells in a manner dependent on the presence of cell surface cleaved AREG. Antibodies conjugated with MMAE were cytotoxic in vitro and induced rapid regression of established breast tumor xenografts in immunocompromised mice. We further demonstrate that these antibodies recognize the AREG neo-epitope in formalin-fixed, paraffin-embedded tumor tissue, suggesting their utility as a companion diagnostic for patient selection.

Conclusions

This ADC targeting AREG has potential utility in the treatment of breast and other tumors in which proteolytic AREG shedding is a frequent event.

An Insight into GPCR and G-Proteins as Cancer Drivers

G-protein-coupled receptors (GPCRs) are the largest family of cell surface signaling receptors known to play a crucial role in various physiological functions, including tumor growth and metastasis. Various molecules such as hormones, lipids, peptides, and neurotransmitters activate GPCRs that enable the coupling of these receptors to highly specialized transducer proteins, called G-proteins, and initiate multiple signaling pathways. Integration of these intricate networks of signaling cascades leads to numerous biochemical responses involved in diverse pathophysiological activities, including cancer development. While several studies indicate the role of GPCRs in controlling various aspects of cancer progression such as tumor growth, invasion, migration, survival, and metastasis through its aberrant overexpression, mutations, or increased release of agonists, the explicit mechanisms of the involvement of GPCRs in cancer progression is still puzzling. This review provides an insight into the various responses mediated by GPCRs in the development of cancers, the molecular mechanisms involved and the novel pharmacological approaches currently preferred for the treatment of cancer. Thus, these findings extend the knowledge of GPCRs in cancer cells and help in the identification of therapeutics for cancer patients.

AXL cooperates with EGFR to mediate neutrophil elastase-induced migration of prostate cancer cells

Neutrophil elastase (NE) promotes multiple stages of tumorigenesis. However, little is known regarding the molecular mechanisms underlying its stimulatory role. This study shows that NE triggers dose-dependent ERK signaling and cell migration in a panel of prostate cell lines representing the spectrum of prostate cell malignancy. All cell lines tested internalize NE; however, NE endocytosis is not required for ERK activation. Instead, NE acts extracellularly by stimulating the release of amphiregulin to initiate EGFR-dependent signaling. Inhibiting amphiregulin's biological activity with neutralizing antibodies, as well as gene silencing of amphiregulin or EGFR, attenuates NE-induced migration in normal and benign prostatic cells. Alternatively, in prostate cancer cells, knockdown of receptor tyrosine kinase AXL, but not EGFR, impairs both basal and NE-stimulated migration. When prostate cells progress to malignancy, the switch from EGFR-to AXL-dependence in NE-mediated migration implies the potential combined application of EGFR and AXL targeted therapy in prostate cancer treatment.

Lysophosphatidic Acid-Induced EGFR Transactivation Promotes Gastric Cancer Cell DNA Replication by Stabilizing Geminin in the S Phase

Geminin, an inhibitor of the DNA replication licensing factor, chromatin licensing and DNA replication factor (Cdt) 1, is essential for the maintenance of genomic integrity. As a multifunctional protein, geminin is also involved in tumor progression, but the molecular details are largely unknown. Here, we found that lysophosphatidic acid (LPA)–induced upregulation of geminin was specific to gastric cancer cells. LPA acted via LPA receptor (LPAR) 3 and matrix metalloproteinases (MMPs) signaling to transactivate epidermal growth factor receptor (EGFR) (Y1173) and thereby stabilize geminin expression level during the S phase. LPA also induced the expression of deubiquitinating protein (DUB) 3, which prevented geminin degradation. These results reveal a novel mechanism underlying gastric cancer progression that involves the regulation of geminin stability by LPA-induced EGFR transactivation and provide potential targets for the signaling pathway and tumor cell–specific inhibitors.

Amphiregulin increases migration and proliferation of epithelial ovarian cancer cells by inducing its own expression via PI3-kinase signaling

The epidermal growth factor receptor (EGFR) is overexpressed in many types of cancer, including epithelial ovarian cancer (EOC), and its expression has been found to correlate with advanced stage and poor prognosis. The EGFR ligand amphiregulin (AREG) has been investigated as a target for human cancer therapy and is known to have an autocrine role in many cancers. A cytokine array identified AREG as one of several cytokines upregulated by EGF in a phosphatidylinositol 3-kinase (PI3-K) dependent manner in EOC cells. To investigate the functional role of AREG in EOC, its effect on cellular migration and proliferation was assessed in two EOC cells lines, OV167 and SKOV3. AREG increased both migration and proliferation of EOC cell line models through activation of PI3-K signaling, but independent of mitogen activated protein kinase (MAPK) signaling. Through an AREG autocrine loop mediated via PI3-K, upregulation of AREG led to increased levels of both AREG transcript and secreted AREG, while downregulation of endogenous AREG decreased the ability of exogenous AREG to induce cell migration and proliferation. Further, inhibition of endogenous AREG activity or metalloproteinase activity decreased EGF-induced EOC migration and proliferation, indicating a role for soluble endogenous AREG in mediating the functional effects of EGFR in inducing migration and proliferation in EOC.

Contribution of ADAM17 and related ADAMs in cardiovascular diseases

A disintegrin and metalloproteases (ADAMs) are key mediators of cell signaling by ectodomain shedding of various growth factors, cytokines, receptors and adhesion molecules at the cellular membrane. ADAMs regulate cell proliferation, cell growth, inflammation, and other regular cellular processes. ADAM17, the most extensively studied ADAM family member, is also known as tumor necrosis factor (TNF)-α converting enzyme (TACE). ADAMs-mediated shedding of cytokines such as TNF-α orchestrates immune system or inflammatory cascades and ADAMs-mediated shedding of growth factors causes cell growth or proliferation by transactivation of the growth factor receptors including epidermal growth factor receptor. Therefore, increased ADAMs-mediated shedding can induce inflammation, tissue remodeling and dysfunction associated with various cardiovascular diseases such as hypertension and atherosclerosis, and ADAMs can be a potential therapeutic target in these diseases. In this review, we focus on the role of ADAMs in cardiovascular pathophysiology and cardiovascular diseases. The main aim of this review is to stimulate new interest in this area by highlighting remarkable evidence.

ADAM10 mediates ectopic proximal tubule development and renal fibrosis through Notch signalling

Disturbed intrauterine development increases the risk of renal disease. Various studies have reported that Notch signalling plays a significant role in kidney development and kidney diseases. A disintegrin and metalloproteinase domain 10 (ADAM10), an upstream protease of the Notch pathway, is also reportedly involved in renal fibrosis. However, how ADAM10 interacts with the Notch pathway and causes renal fibrosis is not fully understood. In this study, using a prenatal chlorpyrifos (CPF) exposure mouse model, we investigated the role of the ADAM10/Notch axis in kidney development and fibrosis. We found that prenatal CPF‐exposure mice presented overexpression of Adam10, Notch1 and Notch2, and led to premature depletion of Six2⁺ nephron progenitors and ectopic formation of proximal tubules (PTs) in the embryonic kidney. These abnormal phenotypic changes persisted in mature kidneys due to the continuous activation of ADAM10/Notch and showed aggravated renal fibrosis in adults. Finally, both ADAM10 and NOTCH2 expression were positively correlated with the degree of renal interstitial fibrosis in IgA nephropathy patients, and increased ADAM10 expression was negatively correlated with decreased kidney function evaluated by serum creatinine, cystatin C, and estimated glomerular filtration rate. Regression analysis also indicated that ADAM10 expression was an independent risk factor for fibrosis in IgAN. © 2020 The Authors. The Journal of Pathology published by John Wiley & Sons, Ltd. on behalf of The Pathological Society of Great Britain and Ireland.

Lysophosphatidic acid induces tumor necrosis factor-alpha to regulate a pro-inflammatory cytokine network in ovarian cancer

Epithelial ovarian carcinoma tissues express high levels of tumor necrosis factor-alpha (TNF-α) and other inflammatory cytokines. The underlying mechanism leading to the abnormal TNF-α expression in ovarian cancer remains poorly understood. In the current study, we demonstrated that lysophosphatidic acid (LPA), a lipid mediator present in ascites of ovarian cancer patients, induced expression of TNF-α mRNA and release of TNF-α protein in ovarian cancer cells. LPA also induced expression of interleukin-1β (IL-1β) mRNA but no significant increase in IL-1β protein was detected. LPA enhanced TNF-α mRNA through NF-κB-mediated transcriptional activation. Inactivation of ADAM17, a disintegrin and metalloproteinase, with a specific inhibitor TMI-1 or by shRNA knockdown prevented ovarian cancer cells from releasing TNF-α protein in response to LPA, indicating that LPA-mediated TNF-α production relies on both transcriptional upregulations of the TNF-α gene and the activity of ADAM17, the membrane-associated TNF-α-converting enzyme. Like many other biological responses to LPA, induction of TNF-α by LPA also depended on the transactivation of the epidermal growth factor receptor (EGFR). Interestingly, our results revealed that ADAM17 was also the shedding protease responsible for the transactivation of EGFR by LPA in ovarian cancer cells. To explore the biological outcomes of LPA-induced TNF-α, we examined the effects of a TNF-α neutralizing antibody and recombinant TNF-α soluble receptor on LPA-stimulated expression of pro-tumorigenic cytokines and chemokines overexpressed in ovarian cancer. Blockade of TNF-α signaling significantly reduced the production of IL-8, IL-6, and CXCL1, suggesting a hierarchy of mechanisms contributing to the robust expression of the inflammatory mediators in response to LPA in ovarian cancer cells. In contrast, TNF-α inhibition did not affect LPA-dependent cell proliferation. Taken together, our results establish that the bioactive lipid LPA drives the expression of TNF-α to regulate an inflammatory network in ovarian cancer.

ADAM-Mediated Signalling Pathways in Gastrointestinal Cancer Formation

Tumour growth is not solely driven by tumour cell-intrinsic mechanisms, but also depends on paracrine signals provided by the tumour micro-environment. These signals comprise cytokines and growth factors that are synthesized as trans-membrane proteins and need to be liberated by limited proteolysis also termed ectodomain shedding. Members of the family of A disintegrin and metalloproteases (ADAM) are major mediators of ectodomain shedding and therefore initiators of paracrine signal transduction. In this review, we summarize the current knowledge on how ADAM proteases on tumour cells but also on cells of the tumour micro-environment contribute to the formation of gastrointestinal tumours, and discuss how these processes can be exploited pharmacologically.

P2Y2 receptors mediate nucleotide-induced EGFR phosphorylation and stimulate proliferation and tumorigenesis of head and neck squamous cell carcinoma cell lines

OBJECTIVES

To assess functional expression of the P2Y2 nucleotide receptor (P2Y2R) in head and neck squamous cell carcinoma (HNSCC) cell lines and define its role in nucleotide-induced epidermal growth factor receptor (EGFR) transactivation. The use of anti-EGFR therapeutics to treat HNSCC is hindered by intrinsic and acquired drug resistance. Defining novel pathways that modulate EGFR signaling could identify additional targets to treat HNSCC.

MATERIALS AND METHODS

In human HNSCC cell lines CAL27 and FaDu and the mouse oral cancer cell line MOC2, P2Y2R contributions to extracellular nucleotide-induced changes in intracellular free Ca2+ concentration and EGFR and extracellular signal-regulated kinase (ERK1/2) phosphorylation were determined using the ratiometric Ca2+ indicator fura-2 and immunoblot analysis, respectively. Genetic knockout of P2Y2Rs using CRISPR technology or pharmacological inhibition with P2Y2R-selective antagonist AR-C118925 defined P2Y2R contributions to in vivo tumor growth.

RESULTS

P2Y2R agonists UTP and ATP increased intracellular Ca2+ levels and ERK1/2 and EGFR phosphorylation in CAL27 and FaDu cells, responses that were inhibited by AR-C118925 or P2Y2R knockout. P2Y2R-mediated EGFR phosphorylation was also attenuated by inhibition of the adamalysin family of metalloproteases or Src family kinases. P2Y2R knockout reduced UTP-induced CAL27 cell proliferation in vitro and significantly reduced CAL27 and FaDu tumor xenograft volume in vivo. In a syngeneic mouse model of oral cancer, AR-C118925 administration reduced MOC2 tumor volume.

CONCLUSION

P2Y2Rs mediate HNSCC cell responses to extracellular nucleotides and genetic or pharmacological blockade of P2Y2R signaling attenuates tumor cell proliferation and tumorigenesis, suggesting that the P2Y2R represents a novel therapeutic target in HNSCC.

ADAM17 stabilizes its interacting partner inactive Rhomboid 2 (iRhom2) but not inactive Rhomboid 1 (iRhom1)

The metalloprotease ADAM17 (a disintegrin and metalloprotease 17) is a key regulator of tumor necrosis factor α (TNFα), interleukin 6 receptor (IL-6R), and epidermal growth factor receptor (EGFR) signaling. ADAM17 maturation and function depend on the seven-membrane-spanning inactive rhomboid-like proteins 1 and 2 (iRhom1/2 or Rhbdf1/2). Most studies to date have focused on overexpressed iRhom1 and -2, so only little is known about the properties of the endogenous proteins. Here, we show that endogenous iRhom1 and -2 can be cell surface-biotinylated on mouse embryonic fibroblasts (mEFs), revealing that endogenous iRhom1 and -2 proteins are present on the cell surface and that iRhom2 also is present on the surface of lipopolysaccharide-stimulated primary bone marrow-derived macrophages. Interestingly, very little, if any, iRhom2 was detectable in mEFs or bone marrow-derived macrophages lacking ADAM17, suggesting that iRhom2 is stabilized by ADAM17. By contrast, the levels of iRhom1 were slightly increased in the absence of ADAM17 in mEFs, indicating that its stability does not depend on ADAM17. These findings support a model in which iRhom2 and ADAM17 are obligate binding partners and indicate that iRhom2 stability requires the presence of ADAM17, whereas iRhom1 is stable in the absence of ADAM17.

Substrate-selective protein ectodomain shedding by ADAM17 and iRhom2 depends on their juxtamembrane and transmembrane domains

The metalloprotease ADAM17 (a disintegrin and metalloprotease 17) regulates EGF-receptor and TNFα signaling, thereby not only protecting the skin and intestinal barrier, but also contributing to autoimmunity. ADAM17 can be rapidly activated by many stimuli through its transmembrane domain (TMD), with the seven membrane-spanning inactive Rhomboids (iRhom) 1 and 2 implicated as candidate regulatory partners. However, several alternative models of ADAM17 regulation exist that do not involve the iRhoms, such as regulation through disulfide bond exchange or through interaction with charged phospholipids. Here, we report that a non-activatable mutant of ADAM17 with the TMD of betacellulin (BTC) can be rescued by restoring residues from the ADAM17 TMD, but only in Adam17^-/- cells, which contain iRhoms, not in iRhom1/2^-/- cells. We also provide the first evidence that the extracellular juxtamembrane domains (JMDs) of ADAM17 and iRhom2 regulate the stimulation and substrate selectivity of ADAM17. Interestingly, a point mutation in the ADAM17 JMD identified in a patient with Tetralogy of Fallot, a serious heart valve defect, affects the substrate selectivity of ADAM17 toward Heparin-binding epidermal growth factor like growth factor (HB-EGF), a crucial regulator of heart valve development in mice. These findings provide new insights into the regulation of ADAM17 through an essential interaction with the TMD1 and JMD1 of iRhom2.

Role of Heparin-Binding Epidermal Growth Factor-Like Growth Factor in Oxidative Stress-Associated Metabolic Diseases

Heparin-binding EGF-like growth factor (HB-EGF) is an EGF family member that interacts with epidermal growth factor receptor (EGFR) and ERBB4. Since HB-EGF was first identified as a novel growth factor secreted from a human macrophage cell line, numerous pathological and physiological functions related to cell proliferation, migration, and inflammation have been reported. Notably, the expression of HB-EGF is sensitively upregulated by oxidative stress in the endothelial cells and functions for auto- and paracrine-EGFR signaling. Overnutrition and obesity cause elevation of HB-EGF expression and EGFR signaling in the hepatic and vascular systems. Modulations of HB-EGF signaling showed a series of protections against phenotypes related to metabolic syndrome and advanced metabolic diseases, suggesting HB-EGF as a potential target against metabolic diseases.

Inverse Correlation of STAT3 and MEK Signaling Mediates Resistance to RAS Pathway Inhibition in Pancreatic Cancer

Major contributors to therapeutic resistance in pancreatic ductal adenocarcinoma (PDAC) include Kras mutations, a dense desmoplastic stroma that prevents drug delivery to the tumor, and activation of redundant signaling pathways. We have previously identified a mechanistic rationale for targeting STAT3 signaling to overcome therapeutic resistance in PDAC. In this study, we investigate the molecular mechanisms underlying the heterogeneous response to STAT3 and RAS pathway inhibition in PDAC. Effects of JAK/STAT3 inhibition (STAT3i) or MEK inhibition (MEKi) were established in Ptf1a^cre/+; LSL-Kras^G12D/+ ; and Tgfbr2^flox/flox (PKT) mice and patient-derived xenografts (PDX). Amphiregulin (AREG) levels were determined in serum from human patients with PDAC, LSL-Kras^G12D/+;Trp53^R172H/+;Pdx1^Cre/+ (KPC), and PKT mice. MEKi/STAT3i-treated tumors were analyzed for integrity of the pancreas and the presence of cancer stem cells (CSC). We observed an inverse correlation between ERK and STAT3 phosphorylation. MEKi resulted in an immediate activation of STAT3, whereas STAT3i resulted in TACE-induced, AREG-dependent activation of EGFR and ERK. Combined MEKi/STAT3i sustained blockade of ERK, EGFR, and STAT3 signaling, overcoming resistance to individual MEKi or STAT3i. This combined inhibition attenuated tumor growth in PDX and increased survival of PKT mice while reducing serum AREG levels. Furthermore, MEKi/STAT3i altered the PDAC tumor microenvironment by depleting tumor fibrosis, maintaining pancreatic integrity, and downregulating CD44⁺ and CD133⁺ CSCs. These results demonstrate that resistance to MEKi is mediated through activation of STAT3, whereas TACE-AREG-EGFR-dependent activation of RAS pathway signaling confers resistance to STAT3 inhibition. Combined MEKi/STAT3i overcomes these resistances and provides a novel therapeutic strategy to target the RAS and STAT3 pathway in PDAC.Significance: This report describes an inverse correlation between MEK and STAT3 signaling as key mechanisms of resistance in PDAC and shows that combined inhibition of MEK and STAT3 overcomes this resistance and provides an improved therapeutic strategy to target the RAS pathway in PDAC.Graphical Abstract: http://cancerres.aacrjournals.org/content/canres/78/21/6235/F1.large.jpg Cancer Res; 78(21); 6235-46. ©2018 AACR.

ADAM17 promotes cell migration and invasion through the integrin β1 pathway in hepatocellular carcinoma

ADAM17 is believed to promote tumor development by facilitating both cell proliferation and migration. In this study, we investigated the involvement of ADAM17 and the activation of the integrin pathway in the regulation of the malignant properties of hepatocellular carcinoma cells and tissues. ADAM17 was positively correlated with active integrin β1, which was determined using a human tissue microarray and an N-nitrosodiethylamine-induced HCC mouse model. We found elevated ADAM17 and active integrin β1 levels in HCC tissues compared with adjacent liver tissues, and the active integrin β1 levels were associated with tumor size and TNM grade. High ADAM17 and active integrin β1 levels in tumor tissues were significantly associated with poor survival of HCC patients. RNAi-mediated ADAM17 knockdown and integrin β1 blockade significantly attenuated the migration and invasion of HCC cells, and overexpression of ADAM17 showed the reverse effects. ADAM17 interference attenuated the intrahepatic growth and metastasis of HCC cells in an orthotopic xenograft model. ADAM17-knockdown cells showed diminished levels of active integrin β1, p-FAK, p-AKT, MMP-2 and MMP-9. ADAM17 knockdown significantly attenuated the translocation of the Notch1 intracellular domain into the nucleus, whereas overexpression of the Notch1 intracellular domain rescued the translocation and enhanced the activation of integrin β1. Our data provide evidence for ADAM17 as an important determinant of malignant properties via regulation of integrin β1 activation and Notch1 signaling. Inhibition of ADAM17 may provide viable therapeutic potential for preventing HCC metastasis.

G Protein Coupled Receptor-mediated Transactivation of Extracellular Proteases

G protein-coupled receptors (GPCRs) comprise the largest family of receptors in humans. Traditional activation of GPCRs involves binding of a ligand to the receptor, activation of heterotrimeric G proteins and induction of subsequent signaling molecules. It is now known that GPCR signaling occurs through G protein-independent pathways including signaling through β-arrestin and transactivation of other receptor types. Generally, transactivation occurs when activation of one receptor leads to the activation of another receptor(s). GPCR-mediated transactivation is an essential component of GPCR signaling, as activation of other receptor types, such as receptor tyrosine kinases, allows GPCRs to expand their signal transduction and affect various cellular responses. Several mechanisms have been identified for receptor transactivation downstream of GPCRs, one of which involves activation of extracellular proteases, such as a disintegrin and metalloprotease, and matrix metalloproteases . These proteases cleave and release ligands that are then able to activate their respective receptors. A disintegrin and metalloprotease, and matrix metalloproteases can be activated via various mechanisms downstream of GPCR activation, including activation via second messenger, direct phosphorylation, or direct G protein interaction. Additional understanding of the mechanisms involved in GPCR-mediated protease activation and subsequent receptor transactivation could lead to identification of new therapeutic targets.

An ADAM12 and FAK positive feedback loop amplifies the interaction signal of tumor cells with extracellular matrix to promote esophageal cancer metastasis

Esophageal squamous cell carcinomas (ESCCs) have a poor prognosis mostly due to early metastasis. To explore the early event of metastasis in ESCC, we established an in vitro selection model to mimic the interaction of tumor cells with extracellular matrix, through which a sub-line of ESCC cells with high invasive ability was generated. By comparing the gene expression profile of the highly invasive sub-line to that of the parental cells, ADAM12-L was identified as a candidate gene promoting ESCC cell invasion. Immunohistochemistry revealed that the ADAM12-L was overexpressed in human ESCC tissues, especially at cancer invasive edge, and ADAM12-L overexpression tightly correlated with increased metastasis and poor outcome of ESCC patients. Indeed, ADAM12-L knockdown reduced the invasion and metastasis of ESCC cells both in vitro and in vivo. Furthermore, we demonstrated that ADAM12-L participated in focal adhesion turnover and promoted the activation of focal adhesion kinase (FAK), which in turn increased ADAM12-L transcription through FAK/JNK/c-Jun axis. Therefore, a loop initiated from the cancer cell upon the engagement with extracellular matrix through FAK and c-Jun to enhance ADAM12-L expression is established, leading to the positive feedback of further FAK activation and prompting metastasis. Our study indicates that overexpression of ADAM12-L can serve as a precision marker to determine the activation of this loop. Targeting ADAM12-L to disrupt this positive feedback loop represents a promising strategy to treat the metastasis of esophageal cancers.

Tetraspanin-8 promotes hepatocellular carcinoma metastasis by increasing ADAM12m expression

Recent evidence indicates that tetraspanin-8 (TSPAN8) promotes tumor progression and metastasis. In this study, we explored the effects of TSPAN8 and the molecular mechanisms underlying hepatocellular carcinoma (HCC) metastasis using various HCC cell lines, tissues from 149 HCC patients, and animal models of HCC progression. We showed that elevated expression of TSPAN8 promoted HCC invasion in vitro and metastasis in vivo, but did not influence HCC cell proliferation in vitro. Increased TSPAN8 expression in human HCC was predictive of poor survival, and multivariate analyses indicated TSPAN8 expression to be an independent predictor for both postoperative overall survival and relapse-free survival. Importantly, TSPAN8 enhanced HCC invasion and metastasis by increasing ADAM12m expression. We therefore conclude that TSPAN8 and ADAM12m may be useful therapeutic targets for the prevention of HCC progression and metastasis.

The EGFR-ADAM17 Axis in Chronic Obstructive Pulmonary Disease and Cystic Fibrosis Lung Pathology

Chronic obstructive pulmonary disease (COPD) and cystic fibrosis (CF) share molecular mechanisms that cause the pathological symptoms they have in common. Here, we review evidence suggesting that hyperactivity of the EGFR/ADAM17 axis plays a role in the development of chronic lung disease in both CF and COPD. The ubiquitous transmembrane protease A disintegrin and metalloprotease 17 (ADAM17) forms a functional unit with the EGF receptor (EGFR), in a feedback loop interaction labeled the ADAM17/EGFR axis. In airway epithelial cells, ADAM17 sheds multiple soluble signaling proteins by proteolysis, including EGFR ligands such as amphiregulin (AREG), and proinflammatory mediators such as the interleukin 6 coreceptor (IL-6R). This activity can be enhanced by injury, toxins, and receptor-mediated external triggers. In addition to intracellular kinases, the extracellular glutathione-dependent redox potential controls ADAM17 shedding. Thus, the epithelial ADAM17/EGFR axis serves as a receptor of incoming luminal stress signals, relaying these to neighboring and underlying cells, which plays an important role in the resolution of lung injury and inflammation. We review evidence that congenital CFTR deficiency in CF and reduced CFTR activity in chronic COPD may cause enhanced ADAM17/EGFR signaling through a defect in glutathione secretion. In future studies, these complex interactions and the options for pharmaceutical interventions will be further investigated.

Extracellular oxidation in cystic fibrosis airway epithelium causes enhanced EGFR/ADAM17 activity

The EGF receptor (EGFR)/a disintegrin and metalloproteinase 17 (ADAM17) signaling pathway mediates the shedding of growth factors and secretion of cytokines and is involved in chronic inflammation and tissue remodeling. Since these are hallmarks of cystic fibrosis (CF) lung disease, we hypothesized that CF transmembrane conductance regulator (CFTR) deficiency enhances EGFR/ADAM17 activity in human bronchial epithelial cells. In CF bronchial epithelial CFBE41o^- cells lacking functional CFTR (iCFTR^-) cultured at air-liquid interface (ALI) we found enhanced ADAM17-mediated shedding of the EGFR ligand amphiregulin (AREG) compared with genetically identical cells with induced CFTR expression (iCFTR⁺). Expression of the inactive G551D-CFTR did not have this effect, suggesting that active CFTR reduces EGFR/ADAM17 activity. This was confirmed in CF compared with normal differentiated primary human bronchial epithelial cells (HBEC-ALI). ADAM17-mediated AREG shedding was tightly regulated by the EGFR/MAPK pathway. Compared with iCFTR⁺ cells, iCFTR^- cells displayed enhanced apical presentation and phosphorylation of EGFR, in accordance with enhanced EGFR/ADAM17 activity in CFTR-deficient cells. The nonpermeant natural antioxidant glutathione (GSH) strongly inhibited AREG release in iCFTR and in primary HBEC-ALI, suggesting that ADAM17 activity is directly controlled by extracellular redox potentials in differentiated airway epithelium. Furthermore, the fluorescent redox probe glutaredoxin 1-redox-sensitive green fluorescent protein-glycosylphosphatidylinositol (Grx1-roGFP-GPI) indicated more oxidized conditions in the extracellular space of iCFTR^- cells, consistent with the role of CFTR in GSH transport. Our data suggest that in CFTR-deficient airway epithelial cells a more oxidized state of the extracellular membrane, likely caused by defective GSH secretion, leads to enhanced activity of the EGFR/ADAM17 signaling axis. In CF lungs this could contribute to tissue remodeling and hyperinflammation.

Synergistic IL-6 and IL-8 paracrine signalling pathway infers a strategy to inhibit tumour cell migration

Following uncontrolled proliferation, a subset of primary tumour cells acquires additional traits/mutations to trigger phenotypic changes that enhance migration and are hypothesized to be the initiators of metastasis. This study reveals an adaptive mechanism that harnesses synergistic paracrine signalling via IL-6/8, which is amplified by cell proliferation and cell density, to directly promote cell migration. This effect occurs in metastatic human sarcoma and carcinoma cells- but not in normal or non-metastatic cancer cells-, and likely involves the downstream signalling of WASF3 and Arp2/3. The transcriptional phenotype of high-density cells that emerges due to proliferation resembles that of low-density cells treated with a combination of IL-6/8. Simultaneous inhibition of IL-6/8 receptors decreases the expression of WASF3 and Arp2/3 in a mouse xenograft model and reduces metastasis. This study reveals a potential mechanism that promotes tumour cell migration and infers a strategy to decrease metastatic capacity of tumour cells.

Structural modeling defines transmembrane residues in ADAM17 that are crucial for Rhbdf2-ADAM17-dependent proteolysis

A disintegrin and metalloproteinase 17 (ADAM17) controls the release of the pro-inflammatory cytokine tumor necrosis factor α (TNFα, also known as TNF) and is crucial for protecting the skin and intestinal barrier by proteolytic activation of epidermal growth factor receptor (EGFR) ligands. The seven-membrane-spanning protein called inactive rhomboid 2 (Rhbdf2; also known as iRhom2) is required for ADAM17-dependent TNFα shedding and crosstalk with the EGFR, and a point mutation (known as sinecure, sin) in the first transmembrane domain (TMD) of Rhbdf2 (Rhbdf2^sin) blocks TNFα shedding, yet little is known about the underlying mechanism. Here, we used a structure-function analysis informed by structural modeling to evaluate the interaction between the TMD of ADAM17 and the first TMD of Rhbdf2, and the role of this interaction in Rhbdf2-ADAM17-dependent shedding. Moreover, we show that double mutant mice that are homozygous for Rhbdf2^sin/sin and lack Rhbdf1 closely resemble Rhbdf1/2^-/- double knockout mice, highlighting the severe functional impact of the Rhbdf2^sin/sin mutation on ADAM17 during mouse development. Taken together, these findings provide new mechanistic and conceptual insights into the critical role of the TMDs of ADAM17 and Rhbdf2 in the regulation of the ADAM17 and EGFR, and ADAM17 and TNFα signaling pathways.

Quantitative investigation of human cell surface N-glycoprotein dynamics

Surface glycoproteins regulate nearly every extracellular event and they are dynamic for cells to adapt to the ever-changing extracellular environment. These glycoproteins contain a wealth of information on cellular development and disease states, and have significant biomedical implications. Systematic investigation of surface glycoproteins will result in a better understanding of surface protein functions, cellular activities and the molecular mechanisms of disease. However, it is extraordinarily challenging to specifically and globally analyze surface glycoproteins. Here we designed the first method to systematically analyze surface glycoprotein dynamics and measure their half-lives by integrating pulse-chase labeling, selective enrichment of surface glycoproteins, and multiplexed proteomics. The current results clearly demonstrated that surface glycoproteins with catalytic activities were more stable than those with binding and receptor activities. Glycosylation sites located outside of any domain had a notably longer median half-life than those within domains, which strongly suggests that glycans within domains regulate protein interactions with other molecules while those outside of domains mainly play a role in protecting the protein from degradation. This method can be extensively applied to biological and biomedical research.

Giant liposome formation toward the synthesis of well-defined artificial cells

This review focuses on microfluidic technologies for giant liposome formations which emulate environments of biological cells.

Interleukin-1 beta transactivates epidermal growth factor receptor via the CXCL1-CXCR2 axis in oral cancer

Hyperactivation of the epidermal growth factor receptor (EGFR) pathways and chronic inflammation are common characteristics of oral squamous cell carcinoma (OSCC). Previously, we reported that OSCC cells secrete interleukin-1 beta (IL-1β), which promotes the proliferation of the oral premalignant cell line, DOK, and stimulates DOK and OSCC cells to produce the chemokine CXCL1. CXCL1 functions through CXCR2, a G protein-coupled receptor that transactivates EGFR in ovarian and lung cancers. We hypothesized that IL-1β transactivates EGFR through the CXCL1–CXCR2 axis in OSCC. In this study, we demonstrated that tyrosine phosphorylation of EGFR is crucial for the IL-1β-mediated proliferation and subsequent bromodeoxyuridine (BrdU) incorporation of DOK cells because the EGFR inhibitors AG1478 and erlotinib inhibit these abilities in a dose-dependent manner. Addition of IL-1β instantly enhanced CXCL1 expression and secretion (within 15 min) in the DOK and OSCC cell lines. Furthermore, tyrosine phosphorylation of EGFR was significantly enhanced in DOK (1 h) and OSCC (20 min) cell lines after IL-1β treatment, and both cell lines were inhibited on the addition of an IL-1 receptor antagonist (IL-1Ra). CXCL1 treatment resulted in EGFR phosphorylation, whereas the knockdown of CXCL1 expression by lentivirus-mediated shRNA or the addition of the CXCR2 antagonist SB225002 dramatically reduced IL-1β-mediated EGFR phosphorylation and proliferation of DOK cells. Neutralizing antibodies against IL-1β or CXCL1 markedly inhibited the constitutive or IL-1β-induced tyrosine phosphorylation of EGFR in OSCC cells. IL-1β transactivates EGFR through the CXCL1-CXCR2 axis, revealing a novel molecular network in OSCC that is associated with autocrine IL-1β and EGFR signaling.

A-Disintegrin and Metalloproteinase (ADAM) 17 Enzymatically Degrades Interferon-gamma

Interferon-gamma (IFN-γ) is a pleiotropic cytokine that exerts anti-tumor and anti-osteoclastogenic effects. Although transcriptional and post-transcriptional regulation of IFN-γ is well understood, subsequent modifications of secreted IFN-γ are not fully elucidated. Previous research indicates that some cancer cells escape immune surveillance and metastasize into bone tissue by inducing osteoclastic bone resorption. Peptidases of the a-disintegrin and metalloproteinase (ADAM) family are implicated in cancer cell proliferation and tumor progression. We hypothesized that the ADAM enzymes expressed by cancer cells degrades IFN-γ and attenuates IFN-γ-mediated anti-tumorigenic and anti-osteoclastogenic effects. Recombinant ADAM17 degraded IFN-γ into small fragments. The addition of ADAM17 to the culture supernatant of stimulated mouse splenocytes decreased IFN-γ concentration. However, ADAM17 inhibition in the stimulated mouse T-cells prevented IFN-γ degradation. ADAM17-expressing human breast cancer cell lines MCF-7 and MDA-MB-453 also degraded recombinant IFN-γ, but this was attenuated by ADAM17 inhibition. Degraded IFN-γ lost the functionality including the inhibititory effect on osteoclastogenesis. This is the first study to demonstrate the extracellular proteolytic degradation of IFN-γ by ADAM17. These results suggest that ADAM17-mediated degradation of IFN-γ may block the anti-tumorigenic and anti-osteoclastogenic effects of IFN-γ. ADAM17 inhibition may be useful for the treatment of attenuated cancer immune surveillance and/or bone metastases.

Membrane-Tethered Intracellular Domain of Amphiregulin Promotes Keratinocyte Proliferation

The epidermal growth factor receptor (EGFR) and its ligands are essential regulators of epithelial biology, which are often amplified in cancer cells. We have previously shown that shRNA-mediated silencing of one of these ligands, amphiregulin (AREG), results in keratinocyte growth arrest that cannot be rescued by soluble extracellular EGFR ligands. To further explore the functional importance of specific AREG domains, we stably transduced keratinocytes expressing tetracycline-inducible AREG-targeted shRNA with lentiviruses expressing silencing-proof, membrane-tethered AREG cytoplasmic and extracellular domains (AREG-CTD and AREG-ECD), as well as full-length AREG precursor (proAREG). Here we show that growth arrest of AREG-silenced keratinocytes occurs in G2/M and is significantly restored by proAREG and AREG-CTD but not by AREG-ECD. Moreover, the AREG-CTD was sufficient to normalize cell cycle distribution profiles and expression of mitosis-related genes. Our findings uncover an important role of the AREG-CTD in regulating cell division, which may be relevant to tumor resistance to EGFR-directed therapies.

MiR-34a suppresses amphiregulin and tumor metastatic potential of head and neck squamous cell carcinoma (HNSCC)

MiR-34a is a well-known tumor metastasis inhibitor, but only a few target genes involved in metastasis have been identified. In HNSCC, the role of miR-34a in metastasis has not been fully elaborated, and the target gene of miR-34a is still blind. Here we addressed that, the relative lower expression of miR-34a is associated with HNSCC lymphatic metastasis. HNSCC metastasis was found to be strongly suppressed in vitro and in vivo by over-expressing miR-34a. In order to screen the possible target genes of miR-34a in HNSCC, a microarray-based differential mRNA profiling mediated by miR-34a over-expression was performed, and AREG was identified as a pivotal target. We demonstrated that the mRNA and protein levels of AREG were greatly reduced when forcing miR-34a expression. The correlation between AREG mRNA levels and HNSCC metastatic phenotype was also significant in HNSCC tissues (p < 0.01). Moreover, the results of luciferase assay provided the further evidence that miR-34a degraded AREG mRNA through targeting the 3′-UTR site. Restoration of AREG expression partially rescued miR-34a-mediated cell invasion defects in vivo and in vitro. Additionally, Over-expressing miR-34a greatly reduced EGFR and uPA, which were reversed by re-expression of AREG. Taken together, these findings indicate that miR-34a targets AREG, and is essential in inhibition of HNSCC metastasis.

Computational Reconstruction of NFκB Pathway Interaction Mechanisms during Prostate Cancer

Molecular research in cancer is one of the largest areas of bioinformatic investigation, but it remains a challenge to understand biomolecular mechanisms in cancer-related pathways from high-throughput genomic data. This includes the Nuclear-factor-kappa-B (NFκB) pathway, which is central to the inflammatory response and cell proliferation in prostate cancer development and progression. Despite close scrutiny and a deep understanding of many of its members’ biomolecular activities, the current list of pathway members and a systems-level understanding of their interactions remains incomplete. Here, we provide the first steps toward computational reconstruction of interaction mechanisms of the NFκB pathway in prostate cancer. We identified novel roles for ATF3, CXCL2, DUSP5, JUNB, NEDD9, SELE, TRIB1, and ZFP36 in this pathway, in addition to new mechanistic interactions between these genes and 10 known NFκB pathway members. A newly predicted interaction between NEDD9 and ZFP36 in particular was validated by co-immunoprecipitation, as was NEDD9's potential biological role in prostate cancer cell growth regulation. We combined 651 gene expression datasets with 1.4M gene product interactions to predict the inclusion of 40 additional genes in the pathway. Molecular mechanisms of interaction among pathway members were inferred using recent advances in Bayesian data integration to simultaneously provide information specific to biological contexts and individual biomolecular activities, resulting in a total of 112 interactions in the fully reconstructed NFκB pathway: 13 (11%) previously known, 29 (26%) supported by existing literature, and 70 (63%) novel. This method is generalizable to other tissue types, cancers, and organisms, and this new information about the NFκB pathway will allow us to further understand prostate cancer and to develop more effective prevention and treatment strategies.

In molecular research in cancer it remains challenging to uncover biomolecular mechanisms in cancer-related pathways from high-throughput genomic data, including the Nuclear-factor-kappa-B (NFκB) pathway. Despite close scrutiny and a deep understanding of many of the NFκB pathway members’ biomolecular activities, the current list of pathway members and a systems-level understanding of their interactions remains incomplete. In this study, we provide the first steps toward computational reconstruction of interaction mechanisms of the NFκB pathway in prostate cancer. We identified novel roles for 8 genes in this pathway and new mechanistic interactions between these genes and 10 known pathway members. We combined 651 gene expression datasets with 1.4M interactions to predict the inclusion of 40 additional genes in the pathway. Molecular mechanisms of interaction were inferred using recent advances in Bayesian data integration to simultaneously provide information specific to biological contexts and individual biomolecular activities, resulting in 112 interactions in the fully reconstructed NFκB pathway. This method is generalizable, and this new information about the NFκB pathway will allow us to further understand prostate cancer.

Amphiregulin enhances alpha6beta1 integrin expression and cell motility in human chondrosarcoma cells through Ras/Raf/MEK/ERK/AP-1 pathway

Chondrosarcoma is a malignant tumor that produces cartilage matrix. The most lethal aspect is its metastatic property. We demonstrated that amphiregulin (AR) is significantly upregulated in highly aggressive cells. AR silencing markedly suppressed cell migration. Exogenous AR markedly increased cell migration by transactivation of α6β1 integrin expression. A neutralizing α6β1 integrin antibody can abolish AR-induced cell motility. Knockdown of AR inhibits metastasis of cells to the lung in vivo. Furthermore, elevated AR expression is positively correlated with α6β1 integrin levels and higher grades in patients. These findings can potentially serve as biomarker and therapeutic approach for controlling chondrosarcoma metastasis.