CARMA3 Is a Critical Mediator of G Protein-Coupled Receptor and Receptor Tyrosine Kinase-Driven Solid Tumor Pathogenesis

MALT1 substrate cleavage: what is it good for?

CARD-BCL10-MALT1 (CBM) signalosomes connect distal signaling of innate and adaptive immune receptors to proximal signaling pathways and immune activation. Four CARD scaffold proteins (CARD9, 10, 11, 14) can form seeds that nucleate the assembly of BCL10-MALT1 filaments in a cell- and stimulus-specific manner. MALT1 (also known as PCASP1) serves a dual function within the assembled CBM complexes. By recruiting TRAF6, MALT1 acts as a molecular scaffold that initiates IκB kinase (IKK)/NF-κB and c-Jun N-terminal kinase (JNK)/AP-1 signaling. In parallel, proximity-induced dimerization of the paracaspase domain activates the MALT1 protease which exerts its function by cleaving a set of specific substrates. While complete MALT1 ablation leads to immune deficiency, selective destruction of either scaffolding or protease function provokes autoimmune inflammation. Thus, balanced MALT1-TRAF6 recruitment and MALT1 substrate cleavage are critical to maintain immune homeostasis and to promote optimal immune activation. Further, MALT1 protease activity drives the survival of aggressive lymphomas and other non-hematologic solid cancers. However, little is known about the relevance of the cleavage of individual substrates for the pathophysiological functions of MALT1. Unbiased serendipity, screening and computational predictions have identified and validated ~20 substrates, indicating that MALT1 targets a quite distinct set of proteins. Known substrates are involved in CBM auto-regulation (MALT1, BCL10 and CARD10), regulation of signaling and adhesion (A20, CYLD, HOIL-1 and Tensin-3), or transcription (RelB) and mRNA stability/translation (Regnase-1, Roquin-1/2 and N4BP1), indicating that MALT1 often targets multiple proteins involved in similar cellular processes. Here, we will summarize what is known about the fate and functions of individual MALT1 substrates and how their cleavage contributes to the biological functions of the MALT1 protease. We will outline what is needed to better connect critical pathophysiological roles of the MALT1 protease with the cleavage of distinct substrates.

CARMA3 Drives NF-κB Activation and Promotes Intervertebral Disc Degeneration: Involvement of CARMA3-BCL10-MALT1 Signalosome

Intervertebral disc degeneration (IDD) diseases are common and frequent diseases in orthopedics. The caspase recruitment domain (CARD) and membrane-associated guanylate kinase-like protein 3 (CARMA3) is crucial in the activation of the NF-κB pathway. However, the biological function of CARMA3 in IDD remains unknown. Here, CARMA3 expression was elevated in nucleus pulposus (NP) tissues of IDD rats and nutrient deprivation (ND)-induced NP cells. The main pathological manifestations observed in IDD rats were shrinkage of the NP, reduction of NP cells, fibrosis of NP tissues, and massive reduction of proteoglycans. These changes were accompanied by a decrease in the expression of collagen II and aggrecan, an increase in the expression of the extracellular matrix (ECM) catabolic proteases MMP-3, MMP-13, and metalloprotease with ADAMTS-5, and an increase in the activity of the pro-apoptotic protease caspase-3. The expression of p-IκBαSer32/36 and p-p65Ser536 was also upregulated. However, these effects were reversed with the knockdown of CARMA3. Mechanistically, CARMA3 bound to BCL10 and MALT1 to form a signalosome. Knockdown of CARMA3 reduced the CARMA3-BCL10-MALT1 signalosome-mediated NF-κB activation. CARMA3 activated the NF-κB signaling pathway in a manner that bound to BCL10 and MALT1 to form a signalosome, which affects NP cell damage and is involved in the development of IDD. This supports CARMA3-BCL10-MALT1-NF-κB as a promising targeting axis for the treatment of IDD.

The paracaspase MALT1 is a downstream target of Smad3 and potentiates the crosstalk between TGF-β and NF-kB signaling pathways in cancer cells

TGF-β signaling mediates its biological effects by engaging canonical Smad proteins and crosstalking extensively with other signaling networks, including the NF-kB pathway. The paracaspase MALT1 is an intracellular signaling molecule essential for NF-kB activation downstream of several key cell surface receptors. Despite intensive research on TGF-β and NF-kB interactions, the significance of MALT1 in this context remains undecoded. Here we provide experimental evidence supporting that MALT1 functions to converge these pathways. Using A549 and Huh7 cancer cell line models, we report that TGF-β stimulation enhances MALT1 protein and transcript levels in a time- and dose-dependent manner. Systematic and selective perturbation of TGF-β signaling components identifies MALT1 as a downstream target of Smad3. Rescue experiments in SMAD3 knockout cells confirm that C-terminal phosphorylation of Smad3 is central to MALT1 induction. Corroborating these data, we document that the expression of SMAD3 and MALT1 genes are positively correlated in TCGA cohorts, and we trace the molecular basis of MALT1 elevation to promoter activation. Functional studies in parental as well as NF-kB p65 signaling reporter engineered cells conclusively reveal that MALT1 is paramount for TGF-β-stimulated nuclear translocation and transcriptional activation of NF-kB p65. Furthermore, we find that BCL10 is also implicated in TGF-β activation of NF-kB target genes, potentially coupling the TGF-β-MALT1-NF-kB signaling axis to the CARMA-BCL10-MALT1 (CBM) signalosome. The novel findings of this study indicate that MALT1 is a downstream target of the canonical TGF-β/Smad3 pathway and plays a critical role in modulating TGF-β and NF-kB crosstalk in cancer.

Function and targeting of MALT1 paracaspase in cancer

The paracaspase MALT1 has emerged as a key regulator of immune signaling, which also promotes tumor development by both cancer cell-intrinsic and -extrinsic mechanisms. As an integral subunit of the CARD11-BCL10-MALT1 (CBM) signaling complex, MALT1 has an intriguing dual function in lymphocytes. MALT1 acts as a scaffolding protein to drive activation of NF-κB transcription factors and as a protease to modulate signaling and immune activation by cleavage of distinct substrates. Aberrant MALT1 activity is critical for NF-κB-dependent survival and proliferation of malignant cancer cells, which is fostered by paracaspase-catalyzed inactivation of negative regulators of the canonical NF-κB pathway like A20, CYLD and RelB. Specifically, B cell receptor-addicted lymphomas rely strongly on this cancer cell-intrinsic MALT1 protease function, but also survival, proliferation and metastasis of certain solid cancers is sensitive to MALT1 inhibition. Beyond this, MALT1 protease exercises a cancer cell-extrinsic role by maintaining the immune-suppressive function of regulatory T (Treg) cells in the tumor microenvironment (TME). MALT1 inhibition is able to convert immune-suppressive to pro-inflammatory Treg cells in the TME of solid cancers, thereby eliciting a robust anti-tumor immunity that can augment the effects of checkpoint inhibitors. Therefore, the cancer cell-intrinsic and -extrinsic tumor promoting MALT1 protease functions offer unique therapeutic opportunities, which has motivated the development of potent and selective MALT1 inhibitors currently under pre-clinical and clinical evaluation.

CARMA3: A potential therapeutic target in non-cancer diseases

Caspase recruitment domain and membrane-associated guanylate kinase-like protein 3 (CARMA3) is a scaffold protein widely expressed in non-hematopoietic cells. It is encoded by the caspase recruitment domain protein 10 (CARD10) gene. CARMA3 can form a CARMA3-BCL10-MALT1 complex by recruiting B cell lymphoma 10 (BCL10) and mucosa-​associated lymphoid tissue lymphoma translocation protein 1 (MALT1), thereby activating nuclear factor-​κB (NF-κB), a key transcription factor that involves in various biological responses. CARMA3 mediates different receptors-dependent signaling pathways, including G protein-coupled receptors (GPCRs) and receptor tyrosine kinases (RTKs). Inappropriate expression and activation of GPCRs and/or RTKs/CARMA3 signaling lead to the pathogenesis of human diseases. Emerging studies have reported that CARMA3 mediates the development of various types of cancers. Moreover, CARMA3 and its partners participate in human non-cancer diseases, including atherogenesis, abdominal aortic aneurysm, asthma, pulmonary fibrosis, liver fibrosis, insulin resistance, inflammatory bowel disease, and psoriasis. Here we provide a review on its structure, regulation, and molecular function, and further highlight recent findings in human non-cancerous diseases, which will provide a novel therapeutic target.

Combining precision oncology and immunotherapy by targeting the MALT1 protease

An innovative strategy for cancer therapy is to combine the inhibition of cancer cell-intrinsic oncogenic signaling with cancer cell-extrinsic immunological activation of the tumor microenvironment (TME). In general, such approaches will focus on two or more distinct molecular targets in the malignant cells and in cells of the surrounding TME. In contrast, the protease Mucosa-associated lymphoid tissue protein 1 (MALT1) represents a candidate to enable such a dual approach by engaging only a single target. Originally identified and now in clinical trials as a lymphoma drug target based on its role in the survival and proliferation of malignant lymphomas addicted to chronic B cell receptor signaling, MALT1 proteolytic activity has recently gained additional attention through reports describing its tumor-promoting roles in several types of non-hematological solid cancer, such as breast cancer and glioblastoma. Besides cancer cells, regulatory T (Treg) cells in the TME are particularly dependent on MALT1 to sustain their immune-suppressive functions, and MALT1 inhibition can selectively reprogram tumor-infiltrating Treg cells into Foxp3-expressing proinflammatory antitumor effector cells. Thereby, MALT1 inhibition induces local inflammation in the TME and synergizes with anti-PD-1 checkpoint blockade to induce antitumor immunity and facilitate tumor control or rejection. This new concept of boosting tumor immunotherapy in solid cancer by MALT1 precision targeting in the TME has now entered clinical evaluation. The dual effects of MALT1 inhibitors on cancer cells and immune cells therefore offer a unique opportunity for combining precision oncology and immunotherapy to simultaneously impair cancer cell growth and neutralize immunosuppression in the TME. Further, MALT1 targeting may provide a proof of concept that modulation of Treg cell function in the TME represents a feasible strategy to augment the efficacy of cancer immunotherapy. Here, we review the role of MALT1 protease in physiological and oncogenic signaling, summarize the landscape of tumor indications for which MALT1 is emerging as a therapeutic target, and consider strategies to increase the chances for safe and successful use of MALT1 inhibitors in cancer therapy.

The Gab2-MALT1 axis regulates thromboinflammation and deep vein thrombosis

Deep vein thrombosis (DVT) is the third most common cause of cardiovascular mortality. Several studies suggest that DVT occurs at the intersection of dysregulated inflammation and coagulation upon activation of inflammasome and secretion of interleukin 1β (IL-1β) in restricted venous flow conditions. Our recent studies showed a signaling adapter protein, Gab2 (Grb2-associated binder 2), plays a crucial role in propagating inflammatory signaling triggered by IL-1β and other inflammatory mediators in endothelial cells. The present study shows that Gab2 facilitates the assembly of the CBM (CARMA3 [CARD recruited membrane-associated guanylate kinase protein 3]-BCL-10 [B-cell lymphoma 10]-MALT1 [mucosa-associated lymphoid tissue lymphoma translocation protein 1]) signalosome, which mediates the activation of Rho and NF-κB in endothelial cells. Gene silencing of Gab2 or MALT1, the effector signaling molecule in the CBM signalosome, or pharmacological inhibition of MALT1 with a specific inhibitor, mepazine, significantly reduced IL-1β-induced Rho-dependent exocytosis of P-selectin and von Willebrand factor (VWF) and the subsequent adhesion of neutrophils to endothelial cells. MALT1 inhibition also reduced IL-1β-induced NF-κB-dependent expression of tissue factor and vascular cell adhesion molecule 1. Consistent with the in vitro data, Gab2 deficiency or pharmacological inhibition of MALT1 suppressed the accumulation of monocytes and neutrophils at the injury site and attenuated venous thrombosis induced by the inferior vena cava ligation-induced stenosis or stasis in mice. Overall, our data reveal a previously unrecognized role of the Gab2-MALT1 axis in thromboinflammation. Targeting the Gab2-MALT1 axis with MALT1 inhibitors may become an effective strategy to treat DVT by suppressing thromboinflammation without inducing bleeding complications.

Carma3 Protects from Liver Injury by Preserving Mitochondrial Integrity in Liver Sinusoidal Endothelial Cells

Carma3 is an intracellular scaffolding protein that can form complex with Bcl10 and Malt1 to mediate G protein–coupled receptor– or growth factor receptor–induced NF-κB activation. However, the in vivo function of Carma3 has remained elusive. Here, by establishing a Con A–induced autoimmune hepatitis model, we show that liver injury is exacerbated in Carma3−/− mice. Surprisingly, we find that the Carma3 expression level is higher in liver sinusoidal endothelial cells (LSECs) than in hepatocytes in the liver. In Carma3−/− mice, Con A treatment induces more LSEC damage, accompanied by severer coagulation. In vitro we find that Carma3 localizes at mitochondria and Con A treatment can trigger more mitochondrial damage and cell death in Carma3-deficient LSECs. Taken together, our data uncover an unrecognized role of Carma3 in maintaining LSEC integrity, and these results may extend novel strategies to prevent liver injury from toxic insults.

MALT1 is a Targetable Driver of Epithelial-to-Mesenchymal Transition in Claudin-low, Triple-Negative Breast Cancer

MALT1 is the effector protein of the CARMA/Bcl10/MALT1 (CBM) signalosome, a multi-protein complex that drives pro-inflammatory signaling pathways downstream of a diverse set of receptors. While CBM activity is best known for its role in immune cells, emerging evidence suggests that it plays a key role in the pathogenesis of solid tumors, where it can be activated by selected G protein-coupled receptors (GPCRs). Here, we demonstrated that overexpression of GPCRs implicated in breast cancer pathogenesis, specifically the receptors for Angiotensin II and thrombin (AT1R and PAR1), drove a strong epithelial-to-mesenchymal transition (EMT) program in breast cancer cells that is characteristic of claudin-low, triple-negative breast cancer (TNBC). In concert, MALT1 was activated in these cells and contributed to the dramatic EMT phenotypic changes through regulation of master EMT transcription factors including Snail and ZEB1. Importantly, blocking MALT1 signaling, through either siRNA-mediated depletion of MALT1 protein or pharmacologic inhibition of its activity, was effective at partially reversing the molecular and phenotypic indicators of EMT. Treatment of mice with mepazine, a pharmacologic MALT1 inhibitor, reduced growth of PAR1+, MDA-MB-231 xenografts and had an even more dramatic effect in reducing the burden of metastatic disease. These findings highlight MALT1 as an attractive therapeutic target for claudin-low TNBCs harboring overexpression of one or more selected GPCRs. Implications: This study nominates a GPCR/MALT1 signaling axis as a pathway that can be pharmaceutically targeted to abrogate EMT and metastatic progression in TNBC, an aggressive form of breast cancer that currently lacks targeted therapies.

A Claudin-Based Molecular Signature Identifies High-Risk, Chemoresistant Colorectal Cancer Patients

Identifying molecular characteristics that are associated with aggressive cancer phenotypes through gene expression profiling can help predict treatment responses and clinical outcomes. Claudins are deregulated in colorectal cancer (CRC). In CRC, increased claudin-1 expression results in epithelial-to-mesenchymal transition and metastasis, while claudin-7 functions as a tumor suppressor. In this study, we have developed a molecular signature based on claudin-1 and claudin-7 associated with poor patient survival and chemoresistance. This signature was validated using an integrated approach including publicly available datasets and CRC samples from patients who either responded or did not respond to standard-of-care treatment, CRC cell lines, and patient-derived rectal and colon tumoroids. Transcriptomic analysis from a patient dataset initially yielded 23 genes that were differentially expressed along with higher claudin-1 and decreased claudin-7. From this analysis, we selected a claudins-associated molecular signature including PIK3CA, SLC6A6, TMEM43, and ASAP-1 based on their importance in CRC. The upregulation of these genes and their protein products was validated using multiple CRC patient datasets, in vitro chemoresistant cell lines, and patient-derived tumoroid models. Additionally, blocking these genes improved 5-FU sensitivity in chemoresistant CRC cells. Our findings propose a new claudin-based molecular signature that associates with poor prognosis as well as characteristics of treatment-resistant CRC including chemoresistance, metastasis, and relapse.

CARMA3 Transcriptional Regulation of STMN1 by NF-κB Promotes Renal Cell Carcinoma Proliferation and Invasion

CARD-containing MAGUK protein 3 (CARMA3) is associated with tumor occurrence and progression. However, the signaling pathways involved in CARMA3 function remain unclear. We aimed to analyze the association between CARMA3 and stathmin (STMN1) through the NF-κB pathway, which is associated with cell proliferation and invasion, in clear cell renal cell carcinoma (ccRCC). We evaluated the effects of CARMA3 and STMN1 expression on cell migration, proliferation, and invasion in various cell lines, and their expression in tissue samples from patients with ccRCC. CARMA3 was highly expressed in ccRCC tissues and cell lines. Moreover, CARMA3 promoted the proliferation and invasion of RCC cells by activating the NF-κB pathway to transcribe STMN1. Stathmin exhibited a consistent profile with CARMA3 in ccRCC tissue, and could be an effector for CARMA3-activated cell proliferation and invasion of ccRCC cells. In summary, CARMA3 may serve as a promising target for ccRCC treatment.

CARD10 cleavage by MALT1 restricts lung carcinoma growth in vivo

CARD-CC complexes involving BCL10 and MALT1 are major cellular signaling hubs. They govern NF-κB activation through their scaffolding properties as well as MALT1 paracaspase function, which cleaves substrates involved in NF-κB regulation. In human lymphocytes, gain-of-function defects in this pathway lead to lymphoproliferative disorders. CARD10, the prototypical CARD-CC protein in non-hematopoietic cells, is overexpressed in several cancers and has been associated with poor prognosis. However, regulation of CARD10 remains poorly understood. Here, we identified CARD10 as the first MALT1 substrate in non-hematopoietic cells and showed that CARD10 cleavage by MALT1 at R587 dampens its capacity to activate NF-κB. Preventing CARD10 cleavage in the lung tumor A549 cell line increased basal levels of IL-6 and extracellular matrix components in vitro, and led to increased tumor growth in a mouse xenograft model, suggesting that CARD10 cleavage by MALT1 might be a built-in mechanism controlling tumorigenicity.

Targeting BCL10 by small peptides for the treatment of B cell lymphoma

Rationale: Constitutive activation of the NF-κB signalling pathway plays a pivotal role in the pathogenesis of activated B cell-like diffuse large B-cell lymphomas (ABC-DLBCLs), the most aggressive and chemoresistant form of DLBCL. In ABC-DLBCLs, the CARMA1-BCL10 (CB) complex forms a filamentous structure and functions as a supramolecular organizing centre (CB-SMOC) that is required for constitutive NF-κB activation, making it an attractive drug target for ABC-DLBCL treatment. However, a pharmaceutical approach targeting CB-SMOC has been lacking. Here, we developed Bcl10 peptide inhibitors (BPIs) that specifically target the BCL10 filamentation process.

Methods: Electron microscopy and immunofluorescence imaging were used to visualize the effect of the BPIs on the BCL10 filamentation process. The cytotoxicity of the tested BPIs was evaluated in DLBCL cell lines according to cell proliferation assays. Different in vitro experiments (pharmacokinetics, immunoprecipitation, western blotting, annexin V and PI staining) were conducted to determine the functional mechanisms of the BPIs. The in vivo therapeutic effect of the BPIs was examined in different xenograft DLBCL mouse models. Finally, Ki67 and TUNEL staining and histopathology analysis were used to evaluate the antineoplastic mechanisms and systemic toxicity of the BPIs.

Results: We showed that these BPIs can effectively disrupt the BCL10 filamentation process, destabilize BCL10 and suppress NF-κB signalling in ABC-DLBCL cells. By examining a panel of DLBCL cell lines, we found that these BPIs selectively repressed the growth of CB-SMOC-dependent DLBCL cells by inducing apoptosis and cell cycle arrest. Moreover, by converting the BPIs to acquire a D-retro inverso (DRI) configuration, we developed DRI-BPIs with significantly improved intracellular stability and unimpaired BPI activity. These DRI-BPIs selectively repressed the growth of CB-SMOC-dependent DLBCL tumors in mouse xenograft models without eliciting discernible adverse effects.

Conclusion: We developed novel BPIs to target the BCL10 filamentation process and demonstrated that targeting BCL10 by BPIs is a potentially safe and effective pharmaceutical approach for the treatment of ABC-DLBCL and other CB-SMOC-dependent malignancies.

Germline CBM-opathies: From immunodeficiency to atopy

Caspase recruitment domain (CARD) protein-B cell CLL/lymphoma 10 (BCL10)-MALT1 paracaspase (MALT1) [CBM] complexes are critical signaling adaptors that facilitate immune and inflammatory responses downstream of both cell surface and intracellular receptors. Germline mutations that alter the function of members of this complex (termed CBM-opathies) cause a broad array of clinical phenotypes, ranging from profound combined immunodeficiency to B-cell lymphocytosis. With an increasing number of patients being described in recent years, the clinical spectrum of diseases associated with CBM-opathies is rapidly expanding and becoming unexpectedly heterogeneous. Here we review major discoveries that have shaped our understanding of CBM complex biology, and we provide an overview of the clinical presentation, diagnostic approach, and treatment options for those carrying germline mutations affecting CARD9, CARD11, CARD14, BCL10, and MALT1.

CARD10 promotes the progression of renal cell carcinoma by regulating the NF‑κB signaling pathway

Previous studies have demonstrated that the expression of CARD10 is closely associated with the occurrence of tumors, and its role is mainly to promote tumor progression by activating the transcription factor NF-κB. However, the signaling pathway in renal cancer remains unclear. The objective of the present study was to investigate the ability of caspase recruitment domain 10 (CARD10) to regulate the NF-κB signaling pathway and promote the progression of renal cell carcinoma (RCC). Expression of CARD10 in ACHN, 786-O and HK-2 cells was evaluated via western blot analysis, as was the epidermal growth factor (EGF)-induced activation of NF-κB signaling pathway-related proteins in cells. The expression of CARD10 was inhibited by CARD10 short hairpin RNA transfection. Cell cycle analysis and MTT assays were used to evaluate cell proliferation. Cell apoptosis was analyzed via flow cytometry. The invasion of renal cell lines was detected via Transwell cell migration and invasion assays in vitro. The results showed that CARD10 expression was significantly higher in RCC cells than in normal renal tubular epithelial cells. CARD10 silencing inhibited the proliferation, invasion and migration of RCC cells. EGF stimulation upregulated the activation of the NF-κB pathway in RCC cells. Inhibition of CARD10 expression inhibited NF-κB activation in RCC cells. Taken together, these data suggested that CARD10 promotes the progression of renal cell carcinoma by regulating the NF-κB signaling pathway. Thus, this indicated that CARD10 may be a novel therapeutic target in RCC.

Caspase recruitment domain family member 10 regulates carbamoyl phosphate synthase 1 and promotes cancer growth in bladder cancer cells

Bladder cancer, which can be divided into non‐muscle‐invasive and muscle‐invasive bladder cancer, is the most common urinary cancer in the United States. Caspase recruitment domain family member 10 (CARD10), also named CARD‐containing MAGUK protein 3 (CARMA3), is a member of the CARMA family and may activate the nuclear factor kappa B (NF‐κB) pathway. We utilized RNA sequencing and metabolic mass spectrometry to identify the molecular and metabolic feature of CARD10. The signalling pathway of CARD10 was verified by Western blotting analysis and functional assays. RNA sequencing and metabolic mass spectrometry of CARD10 knockdown identified the metabolic enzyme carbamoyl phosphate synthase 1 (CPS1) in the urea cycle as the downstream gene regulated by CARD10. We confirmed that CARD10 affected cell proliferation and nucleotide metabolism through regulating CPS1. We indicated that CARD10 promote bladder cancer growth via CPS1 and maybe a potential therapeutic target in bladder cancer.

CARMA3/NF-κB signaling contributes to tumorigenesis of hepatocellular carcinoma and is inhibited by sodium aescinate

BACKGROUND

Primary hepatocellular carcinoma (HCC) is a very malignant tumor in the world. CARMA3 plays an oncogenic role in the pathogenesis of various tumors. However, the function of CARMA3 in HCC has not been fully clarified.

AIM

To study the biological function of CAEMA3 in HCC.

METHODS

Tissue microarray slides including tissues form 100 HCC patients were applied to access the expression of CARMA3 in HCC and its clinical relevance. Knockdown and overexpression of CARMA3 were conducted with plasmid transfection. MTT, colony formation, and apoptosis assays were performed to check the biological activity of cells.

RESULTS

Higher expression of CARMA3 in HCC was relevant to poor prognostic survival (P < 0.05). Down-regulation of CARMA3 inhibited proliferation and colony formation and induced apoptosis in HCC cell lines, while increasing its expression promoted tumorigenesis. We also found that sodium aescinate (SA), a natural herb extract, exerted anti-proliferation effects in HCC cells by suppressing the CARMA3/nuclear factor kappa-B (NF-κB) pathway.

CONCLUSION

Overexpression of CARMA3 in HCC tissues correlates with a poor prognosis in HCC patients. CARMA3 acts pro-tumorigenic effects partly through activation of CARMA3/NF-κB. SA inhibits HCC growth by targeting CARMA3/NF-κB.

MALT1 is a critical mediator of PAR1-driven NF-κB activation and metastasis in multiple tumor types

Protease-activated receptor 1 (PAR1), a thrombin-responsive G protein-coupled receptor (GPCR), is implicated in promoting metastasis in multiple tumor types, including both sarcomas and carcinomas, but the molecular mechanisms responsible remain largely unknown. We previously discovered that PAR1 stimulation in endothelial cells leads to activation of NF-κB, mediated by a protein complex comprised of CARMA3, Bcl10, and the MALT1 effector protein (CBM complex). Given the strong association between NF-κB and metastasis, we hypothesized that this CBM complex could play a critical role in the PAR1-driven metastatic progression of specific solid tumors. In support of our hypothesis, we demonstrate that PAR1 stimulation results in NF-κB activation in both osteosarcoma and breast cancer, which is suppressed by siRNA-mediated MALT1 knockdown, suggesting that an intact CBM complex is required for the response in both tumor cell types. We identify several metastasis-associated genes that are upregulated in a MALT1-dependent manner after PAR1 stimulation in cancer cells, including those encoding the matrix remodeling protein, MMP9, and the cytokines, IL-1β and IL-8. Further, exogenous expression of PAR1 in MCF7 breast cancer cells confers highly invasive and metastatic behavior which can be blocked by CRISPR/Cas9-mediated MALT1 knockout. Importantly, we find that PAR1 stimulation induces MALT1 protease activity in both osteosarcoma and breast cancer cells, an activity that is mechanistically linked to NF-κB activation and potentially other responses associated with aggressive phenotype. Several small molecule MALT1 protease inhibitors have recently been described that could therefore represent promising new therapeutics for the prevention and/or treatment of PAR1-driven tumor metastasis.

Sevoflurane regulates CARMA3 to inhibit migration and invasion of gastric cancer cells by targeting NF-κB signaling pathway

AIM

To investigate the effect of sevoflurane on cell migration and invasion in gastric cancer (GC) cells, and to explore the underlying mechanism.

METHODS

After SGC7901 cells were transfected with siCARMA3 (siCARMA3 group), siControl (NC group), pcDNA 3.1-CARMA3 (CARMA3 group), or pcDNA 3.1 (vector group) by liposome method, the expression of CARMA3 mRNA in cells was detected by qRT-PCR, and the protein expression of CARMA3, p-p65, and p65 was detected by Western blot.

RESULTS

Compared with the control group, sevoflurane inhibited the migration and invasion of GC cells and down-regulated the expression of CARMA3. Silencing of CARMA3 inhibited the migration and invasion of GC cells, while overexpression of CARMA3 promoted the migration and invasion of GC cells. CARMA3 targeted the NF-κB pathway. Thus, sevoflurane regulated CARMA3 to inhibit migration and invasion of GC cells by targeting the NF-κB pathway.

CONCLUSION

Sevoflurane could inhibit the migration and invasion of GC cells via mechanisms that may be related to the regulation of CARMA3 to target the NF-κB pathway. This finding will provide a basis for clinical treatment of GC with sevoflurane.