The Tumor Suppressor Interferon Regulatory Factor 2 Binding Protein 2 Regulates Hippo Pathway in Liver Cancer by a Feedback Loop in Mice

The actin-binding protein drebrin disrupts NF2-LATS kinases complex assembly to facilitate liver tumorigenesis

BACKGROUND AND AIMS

The Hippo signaling has emerged as a crucial regulator of tissue homeostasis, regeneration, and tumorigenesis, representing a promising therapeutic target. Neurofibromin 2 (NF2), a component of Hippo signaling, is directly linked to human cancers but has been overlooked as a target for cancer therapy.

APPROACH AND RESULTS

Through a high-content RNA interference genome-wide screen, the actin-binding protein Drebrin (DBN1) has been identified as a novel modulator of YAP localization. Further investigations have revealed that DBN1 directly interacts with NF2, disrupting the activation of large tumor suppressor kinases (LATS1/2) by competing with LATS kinases for NF2 binding. Consequently, DBN1 knockout considerably promotes YAP nuclear exclusion and repression of target gene expression, thereby preventing cell proliferation and liver tumorigenesis. We identified three lysine residues (K238, K248, and K252) essential for DBN1-NF2 interaction and developed a mutant DBN1 (DBN1-3K mut ) that is defective in NF2 binding and incompetent to trigger NF2-dependent YAP activation and tumorigenesis both in vitro and in vivo. Furthermore, BTP2, a DBN1 inhibitor, successfully restored NF2-LATS kinase binding and elicited potent antitumor activity. The combination of sorafenib and BTP2 exerted synergistic inhibitory effects against HCC.

CONCLUSIONS

Our study identifies a novel DBN1-NF2-LATS axis, and pharmacological inhibition of DBN1 represents a promising alternative intervention targeting the Hippo pathway in cancer treatment.

Super-Enhancer-Driven IRF2BP2 is Activated by Master Transcription Factors and Sustains T-ALL Cell Growth and Survival

Super enhancers (SEs) are large clusters of transcriptional enhancers driving the expression of genes crucial for defining cell identity. In cancer, tumor-specific SEs activate key oncogenes, leading to tumorigenesis. Identifying SE-driven oncogenes in tumors and understanding their functional mechanisms is of significant importance. In this study, a previously unreported SE region is identified in T-cell acute lymphoblastic leukemia (T-ALL) patient samples and cell lines. This SE activates the expression of interferon regulatory factor 2 binding protein 2 (IRF2BP2) and is regulated by T-ALL master transcription factors (TFs) such as ETS transcription factor ERG (ERG), E74 like ETS transcription factor 1 (ELF1), and ETS proto-oncogene 1, transcription factor (ETS1). Hematopoietic system-specific IRF2BP2 conditional knockout mice is generated and showed that IRF2BP2 has minimal impact on normal T cell development. However, in vitro and in vivo experiments demonstrated that IRF2BP2 is crucial for T-ALL cell growth and survival. Loss of IRF2BP2 affects the MYC and E2F pathways in T-ALL cells. Cleavage under targets and tagmentation (CUT&Tag) assays and immunoprecipitation revealed that IRF2BP2 cooperates with the master TFs of T-ALL cells, targeting the enhancer of the T-ALL susceptibility gene recombination activating 1 (RAG1) and modulating its expression. These findings provide new insights into the regulatory network within T-ALL cells, identifying potential new targets for therapeutic intervention.

Malate initiates a proton-sensing pathway essential for pH regulation of inflammation

Metabolites can double as a signaling modality that initiates physiological adaptations. Metabolism, a chemical language encoding biological information, has been recognized as a powerful principle directing inflammatory responses. Cytosolic pH is a regulator of inflammatory response in macrophages. Here, we found that L-malate exerts anti-inflammatory effect via BiP-IRF2BP2 signaling, which is a sensor of cytosolic pH in macrophages. First, L-malate, a TCA intermediate upregulated in pro-inflammatory macrophages, was identified as a potent anti-inflammatory metabolite through initial screening. Subsequent screening with DARTS and MS led to the isolation of L-malate-BiP binding. Further screening through protein‒protein interaction microarrays identified a L-malate-restrained coupling of BiP with IRF2BP2, a known anti-inflammatory protein. Interestingly, pH reduction, which promotes carboxyl protonation of L-malate, facilitates L-malate and carboxylate analogues such as succinate to bind BiP, and disrupt BiP-IRF2BP2 interaction in a carboxyl-dependent manner. Both L-malate and acidification inhibit BiP-IRF2BP2 interaction, and protect IRF2BP2 from BiP-driven degradation in macrophages. Furthermore, both in vitro and in vivo, BiP-IRF2BP2 signal is required for effects of both L-malate and pH on inflammatory responses. These findings reveal a previously unrecognized, proton/carboxylate dual sensing pathway wherein pH and L-malate regulate inflammatory responses, indicating the role of certain carboxylate metabolites as adaptors in the proton biosensing by interactions between macromolecules.

IRF2BP2 binds to a conserved RxSVI motif of protein partners and regulates megakaryocytic differentiation

IRF2BP2 is a transcriptional coregulator that plays diverse regulatory roles in various cellular processes in either IRF2-dependent or IRF2-independent manner through interactions with protein partners via its RING domain; however, the underlying molecular mechanisms remain unclear. In this study, we conduct a motif discovery search on the sequences of interacting proteins IRF2 and VGLL4 of IRF2BP2 and identify a conserved RxSVI motif. Biochemical and structural data reveal that the RING domain binds to the motif-containing peptides of IRF2 and VGLL4 with comparable affinities and in a similar manner. The motif-containing peptides tend to form a short loop along with a short β-strand, which facilitates effective recognition and tight binding by the RING domain. Further exploration of this motif in the human proteome identifies the transcription factor ZBTB16 as an interacting protein of IRF2BP2. Biochemical, structural, and cell biological data demonstrate that the RING domain binds to the motif-containing peptide of ZBTB16 in a manner similar to that of IRF2 and VGLL4. Moreover, IRF2BP2 plays a crucial regulatory role in megakaryocytic differentiation through interaction with ZBTB16. These findings elucidate the molecular basis for how IRF2BP2 can engage with different protein partners, thereby exerting diverse regulatory functions in many cellular processes.

Super-enhancer-driven IRF2BP2 enhances ALK activity and promotes neuroblastoma cell proliferation

BACKGROUND

Super-enhancers (SEs) typically govern the expression of critical oncogenes and play a fundamental role in the initiation and progression of cancer. Focusing on genes that are abnormally regulated by SE in cancer may be a new strategy for understanding pathogenesis. In the context of this investigation, we have identified a previously unreported SE-driven gene IRF2BP2 in neuroblastoma (NB).

METHODS

The expression and prognostic value of IRF2BP2 were detected in public databases and clinical samples. The effect of IRF2BP2 on NB cell growth and apoptosis was evaluated through in vivo and in vitro functional loss experiments. The molecular mechanism of IRF2BP2 was investigated by the study of chromatin regulatory regions and transcriptome sequencing.

RESULTS

The sustained high expression of IRF2BP2 results from the activation of a novel SE established by NB master transcription factors MYCN, MEIS2, and HAND2, and they form a new complex that regulates the gene network associated with the proliferation of NB cell populations. We also observed a significant enrichment of the AP-1 family at the binding sites of IRF2BP2. Remarkably, within NB cells, AP-1 plays a pivotal role in shaping the chromatin accessibility landscape, thereby exposing the binding site for IRF2BP2. This orchestrated action enables AP-1 and IRF2BP2 to collaboratively stimulate the expression of the NB susceptibility gene ALK, thereby upholding the highly proliferative phenotype characteristic of NB.

CONCLUSIONS

Our findings indicate that SE-driven IRF2BP2 can bind to AP-1 to maintain the survival of tumor cells via regulating chromatin accessibility of the NB susceptibility gene ALK.

Glioma stem cell-derived exosomes induce the transformation of astrocytes via the miR-3065-5p/DLG2 signaling axis

Tumor-associated astrocytes (TAAs) in the glioblastoma microenvironment play an important role in tumor development and malignant progression initiated by glioma stem cells (GSCs). In the current study, normal human astrocytes (NHAs) were cultured and continuously treated with GSC-derived exosomes (GSC-EXOs) induction to explore the mechanism by which GSCs affect astrocyte remodeling. This study revealed that GSC-EXOs can induce the transformation of NHAs into TAAs, with relatively swollen cell bodies and multiple extended processes. In addition, high proliferation, elevated resistance to temozolomide (TMZ), and increased expression of TAA-related markers (TGF-β, CD44, and tenascin-C) were observed in the TAAs. Furthermore, GSC-derived exosomal miR-3065-5p could be delivered to NHAs, and miR-3065-5p levels increased significantly in TAAs, as verified by miRNA expression profile sequencing and Reverse transcription polymerase chain reaction. Overexpression of miR-3065-5p also enhanced NHA proliferation, elevated resistance to TMZ, and increased the expression levels of TAA-related markers. In addition, both GSC-EXO-induced and miR-3065-5p-overexpressing NHAs promoted tumorigenesis of GSCs in vivo. Discs Large Homolog 2 (DLG2, downregulated in glioblastoma) is a direct downstream target of miR-3065-5p in TAAs, and DLG2 overexpression could partially reverse the transformation of NHAs into TAAs. Collectively, these data demonstrate that GSC-EXOs induce the transformation of NHAs into TAAs via the miR-3065-5p/DLG2 signaling axis and that TAAs can further promote the tumorigenesis of GSCs. Thus, precisely blocking the interactions between astrocytes and GSCs via exosomes may be a novel strategy to inhibit glioblastoma development, but more in-depth mechanistic studies are still needed.

SPOP point mutations regulate substrate preference and affect its function

The adaptor SPOP recruits substrates to CUL3 E3 ligase for ubiquitination and degradation. Structurally, SPOP harbors a MATH domain for substrate recognition, and a BTB domain responsible for binding CUL3. Reported point mutations always occur in SPOP's MATH domain and are through to disrupt affinities of SPOP to substrates, thereby leading to tumorigenesis. In this study, we identify the tumor suppressor IRF2BP2 as a novel substrate of SPOP. SPOP enables to attenuate IRF2BP2-inhibited cell proliferation and metastasis in HCC cells. However, overexpression of wild-type SPOP alone suppresses HCC cell proliferation and metastasis. In addition, a HCC-derived mutant, SPOP-M35L, shows an increased affinity to IRF2BP2 in comparison with wild-type SPOP. SPOP-M35L promotes HCC cell proliferation and metastasis, suggesting that M35L mutation possibly reprograms SPOP from a tumor suppressor to an oncoprotein. Taken together, this study uncovers mutations in SPOP's MATH lead to distinct functional consequences in context-dependent manners, rather than simply disrupting its interactions with substrates, raising a noteworthy concern that we should be prudent to select SPOP as therapeutic target for cancers.

IRF2BP2 drives lymphatic metastasis in OSCC cells by elevating mitochondrial fission-dependent fatty acid oxidation

Lymph node metastasis (LNM) is a major determinant for the poor outcome of oral squamous cell carcinoma (OSCC). Interferon regulatory factor 2 binding protein 2 (IRF2BP2) has been reported to modulate the development and progression of several types of cancers, while its role in OSCC with LNM has not been reported yet. The expression of IRF2BP2 and its association with LNM were evaluated by immunohistochemistry and qualitative reverse transcription polymerase chain reaction in clinically collected OSCC tissues. Then, loss-of-function and rescue assays were conducted to identify the role of IRF2BP2-mediated fatty acid oxidation (FAO) in the invasion, lymphoinvasion, and epithelial-mesenchymal transition (EMT) in OSCC cells. Importantly, confocal microscope, transmission electron microscope, immunofluorescence, and Western blot were applied to identify the involvement of mitochondrial fission in IRF2BP2-regulated FAO. Lastly, the in vivo models were established to evaluate the role of IRF2BP2 in OSCC. IRF2BP2 overexpression has been associated with LNM in OSCC, whose knockdown inhibited invasion, lymphoinvasion, and EMT of OSCC cells, as well as retarded FAO rate with CPT1A downregulation. And CPT1A overexpression rescued invasion, lymphoinvasion, and induced EMT in IRF2BP2-silenced OSCC cells. Mechanically, IRF2BP2 accelerated mitochondrial fission by contributing to Drp1 S616 phosphorylation and mitochondrial localization, resulting in the upregulation of CPT1A. In addition, IRF2BP2 knockdown significantly inhibited tumor growth and LNM in vivo. The highly expressed IRF2BP2 may induce the phosphorylation and mitochondrial translocation of Drp1 to activate mitochondrial fission, which upregulated CPT1A expression and FAO rate, resulting in LNM in OSCC. This highlighted a potential therapeutic vulnerability for the treatment of LNM+ OSCC via targeting IRF2BP2-FAO.

The Prognostic Significance of the TEAD4 in Hepatocellular Carcinoma

Background

Abnormal expression of genes causes tumorigenesis, tumor progression, and poor prognosis in hepatocellular carcinoma (HCC). Therefore, the aims of this study were to explore the transcription enhancer domain factor 4 (TEAD4) in patients with liver cancer and its relationship with prognosis.

Methods

HTSeq-FPKM data and corresponding clinical data of HCC patients were obtained from The Cancer Genome Atlas (TCGA). Difference in TEAD4 expression between normal and tumor and the correlation with clinical characteristics were analyzed by the chi-squared test based on UALCAN. HepG2 cell lines were used to study the effect of TEAD4 on HCC cell lines. The expression and clinical significance of TEAD4 in HCC were detected in clinical cases.

Results

The transcription and post-transcription levels of TEAD4 were higher in HCC tumors than normal illustrated different expressed transcription of TEAD4 in gender, nodal metastasis status, tumor grades, and individual cancer stages. The high TEAD4 expression was significantly associated with tumor grades. The high expression of TEAD4 was significantly correlated to shorter 2-5 years overall survival. Inhibition of TEAD4 expression in HepG2 cells resulted in significantly decreased cell proliferation and invasion.

Conclusion

TEAD4 was identified as an independent prognostic factor, and inhibition of TEAD4 expression in HepG2 cells resulted in significantly decreased cell proliferation and invasion.

Low RNA stability signifies strong expression regulatability of tumor suppressors

RNA expression of a gene is determined by not only transcriptional regulation, but also post-transcriptional regulation of RNA decay. The precise regulation of RNA stability in the cell plays an important role in normal development. Dysregulation of RNA stability can lead to diseases such as cancer. Here we found tumor suppressor RNAs tended to decay fast in normal cell types when compared with other RNAs. Consistent with a negative effect of m6A modification on RNA stability, we observed preferential deposition of m6A on tumor suppressor RNAs. Moreover, abundant m6A and fast decay of tumor suppressor RNAs both tended to be further enhanced in prostate cancer cells relative to normal prostate epithelial cells. Further, knockdown of m6A methyltransferase METTL3 and reader YTHDF2 in prostate cancer cells both posed stronger effect on tumor suppressor RNAs than on other RNAs. These results indicated a strong post transcriptional expression regulatability mediated by abundant m6A modification on tumor suppressor RNAs.

Hippo Pathway in Schwann Cells and Regeneration of Peripheral Nervous System

Hippo pathway is an evolutionarily conserved signaling pathway comprising a series of MST/LATS kinase complexes. Its key transcriptional coactivators YAP and TAZ regulate transcription factors such as TEAD family to direct gene expression. The regulation of Hippo pathway, especially the nuclear level change of YAP and TAZ, significantly influences the cell fate switching from proliferation to differentiation, regeneration, and postinjury repair. This review outlines the main findings of Hippo pathway in peripheral nerve development, regeneration, and tumorigenesis, especially the studies in Schwann cells. We also summarize other roles of Hippo pathway in damage repair of the peripheral nerve system and discuss the potential future research which probably contributes to novel therapeutic strategies.

Quercetin acts as a novel anti-cancer drug to suppress cancer aggressiveness and cisplatin-resistance in nasopharyngeal carcinoma (NPC) through regulating the yes-associated protein/Hippo signaling pathway

BACKGROUND

Quercetin has been proven to be effective for cancer treatment, including nasopharyngeal carcinoma (NPC). Also, Quercetin sensitizes cancer cells to current chemical drugs to improve their therapeutic efficacy. However, up until now, the molecular mechanisms that quercetin exerted its therapeutic effects on NPC have not been fully delineated.

METHODS

Cell proliferation abilities were examined by CCK-8 assay and colony formation assay. Real-Time qPCR and Western Blot analysis were used to detect gene expressions at RNA and protein levels. Cell mobility was determined by wound scratch assay and transwell assay. Cell death was detected using flow cytometry (FCM). Tumorigenesis of the NPC cells was determined by in vivo tumor-bearing mice models. Hematoxylin and eosin (H&E) and TUNEL staining were used to detect the tumor metastasis to lung tissues and dead cells, respectively.

RESULTS

Here, we validated that quercetin exerted its anti-tumor effects and increased cisplatin-sensitivity in NPC in vitro and in vivo. Specifically, quercetin inhibited NPC cell proliferation, viability, mobility, epithelial-mesenchymal transition (EMT), and tumorigenesis, and induced cell death, resulting in the inhibition of NPC progression. In addition, the NPC cells were subjected to a continuously increasing doses of cisplatin to generate cisplatin-resistant NPC (NPC/CDDP) cells. Interestingly, quercetin significantly enhanced the cytotoxic effects of high-dose cisplatin on NPC/CDDP cells. Furthermore, the potential underlying mechanisms were uncovered, and the results evidenced that quercetin inhibited Yes-associated protein (YAP) expression and its translocation to the nucleus, leading to the recovery of the Hippo pathway, inhibition of cancer progression, and increase in cisplatin-resistance. Mechanistically, upregulation of YAP by its gene manipulating vectors abrogated the inhibiting effects of quercetin on NPC malignant phenotypes, which also made NCP/CDDP cells irresponsive to high-dose cisplatin-quercetin co-treatments.

CONCLUSION

Collectively, our data evidenced that quercetin inhibited YAP to recover the Hippo pathway, which further inhibited NPC pathogenesis and increased susceptibility of NCP/CDDP cells to cisplatin treatment.

LncRNA ATP1A1-AS1 inhibits cell proliferation and promotes cell apoptosis in thyroid carcinoma by regulating the miR-620/IRF2BP2 axis

BACKGROUND

Thyroid carcinoma (THCA) is a common malignancy of the endocrine system. Further understanding of the molecular mechanism underlying THCA is crucial to develop effective diagnostic therapy and improve its treatments. In this study, we intended to provide novel direction for THCA targeted therapy from the aspect of lncRNA-miRNA-mRNA interaction. We aimed to investigate the function and molecular mechanism of lncRNA ATP1A1-AS1 in THCA.

METHODS

Gene expression was assessed by reverse transcription quantitative polymerase chain reaction (RT-qPCR). Cell growth was detected by CCK-8 and EdU assays. Flow cytometry was applied for analyzing cell apoptosis. The binding of ATP1A1-AS1 or IRF2BP2 to miR-620 was validated by RNA pulldown and luciferase reporter assays. The protein levels were examined by western blotting.

RESULTS

ATP1A1-AS1 was decreased in THCA cells and tissues. ATP1A1-AS1 overexpression attenuated cell growth and promoted apoptosis. MiR-620, which was upregulated in THCA, was identified as a direct target of ATP1A1-AS1. Furthermore, IRF2BP2 was discovered to be a target of miR-620, which displayed low expression in THCA cells and tissues. Importantly, IRF2BP2 knockdown reversed the influence of ATP1A1-AS1 overexpression on THCA cell proliferation and apoptosis.

CONCLUSIONS

LncRNA ATP1A1-AS1 inhibited cell growth and promotes apoptosis in THCA via the miR-620/IRF2BP2 axis.

TEAD4 as an Oncogene and a Mitochondrial Modulator

TEAD4 (TEA Domain Transcription Factor 4) is well recognized as the DNA-anchor protein of YAP transcription complex, which is modulated by Hippo, a highly conserved pathway in Metazoa that controls organ size through regulating cell proliferation and apoptosis. To acquire full transcriptional activity, TEAD4 requires co-activator, YAP (Yes-associated protein) or its homolog TAZ (transcriptional coactivator with PDZ-binding motif) the signaling hub that relays the extracellular stimuli to the transcription of target genes. Growing evidence suggests that TEAD4 also exerts its function in a YAP-independent manner through other signal pathways. Although TEAD4 plays an essential role in determining that differentiation fate of the blastocyst, it also promotes tumorigenesis by enhancing metastasis, cancer stemness, and drug resistance. Upregulation of TEAD4 has been reported in several cancers, including colon cancer, gastric cancer, breast cancer, and prostate cancer and serves as a valuable prognostic marker. Recent studies show that TEAD4, but not other members of the TEAD family, engages in regulating mitochondrial dynamics and cell metabolism by modulating the expression of mitochondrial- and nuclear-encoded electron transport chain genes. TEAD4’s functions including oncogenic activities are tightly controlled by its subcellular localization. As a predominantly nuclear protein, its cytoplasmic translocation is triggered by several signals, such as osmotic stress, cell confluency, and arginine availability. Intriguingly, TEAD4 is also localized in mitochondria, although the translocation mechanism remains unclear. In this report, we describe the current understanding of TEAD4 as an oncogene, epigenetic regulator and mitochondrial modulator. The contributing mechanisms will be discussed.

The Transcriptional Co-factor IRF2BP2: A New Player in Tumor Development and Microenvironment

Interferon regulatory factor 2-binding protein 2 (IRF2BP2) encodes a member of the IRF2BP family of transcriptional regulators, which includes IRF2BP1, IRF2BP2, and IRF2BPL (EAP1). IRF2BP2 was initially identified as a transcriptional corepressor that was dependent on Interferon regulatory factor-2 (IRF-2). The IRF2BP2 protein is found in different organisms and has been described as ubiquitously expressed in normal and tumor cells and tissues, indicating a possible role for this transcriptional cofactor in different cell signaling pathways. Recent data suggest the involvement of IRF2BP2 in the regulation of several cellular functions, such as the cell cycle, cell death, angiogenesis, inflammation and immune response, thereby contributing to physiological cell homeostasis. However, an imbalance in IRF2BP2 function may be related to the pathophysiology of cancer. Some studies have shown the association of IRF2BP2 expression in hematopoietic and solid tumors through mechanisms based on gene fusion and point mutations in gene coding sequences, and although the biological functions of these types of hybrid and mutant proteins are not yet known, they are thought to be involved in an increase in the likelihood of tumor development. In this review, we address the possible involvement of IRF2BP2 in tumorigenesis through its regulation of important pathways involved in tumor development.

SEPT6 drives hepatocellular carcinoma cell proliferation, migration and invasion via the Hippo/YAP signaling pathway

Septin 6 (SEPT6) is a member of the GTP-binding protein family that is highly conserved in eukaryotes and regulates various biological functions, including filament dynamics, cytokinesis and cell migration. However, the functional importance of SEPT6 in hepatocellular carcinoma (HCC) is not completely understood. The present study aimed to investigate the expression levels and roles of SEPT6 in HCC, as well as the underlying mechanisms. The reverse transcription quantitative PCR, western blotting and immunohistochemistry staining results demonstrated that SEPT6 expression was significantly elevated in HCC tissues compared with corresponding adjacent non-tumor tissues, which indicated that SEPT6 expression may serve as a marker of poor prognosis for HCC. By performing plasmid transfection and G418 treatment, stable SEPT6-knockdown and SEPT6-overexpression cell lines were established. The Cell Counting Kit-8, flow cytometry and Transwell assay results demonstrated that SEPT6 overexpression significantly increased HCC cell proliferation, cell cycle transition, migration and invasion compared with the Vector group, whereas SEPT6 knockdown displayed significant suppressive effects on HCC cell lines in vitro compared with the control group. Mechanistically, SEPT6 might facilitate F-actin formation, which induced large tumor suppressor kinase 1 dephosphorylation, inhibited Hippo signaling, upregulated yes-associated protein (YAP) expression and nuclear translocation, and upregulated cyclin D1 and matrix metallopeptidase 2 (MMP2) expression. Furthermore, YAP overexpression significantly reversed SEPT6 knockdown-induced inhibitory effects on HCC, whereas YAP knockdown significantly inhibited the oncogenic effect of SEPT6 overexpression on HCC. Collectively, the present study demonstrated that SEPT6 may promote HCC progression by enhancing YAP activation, suggesting that targeting SEPT6 may serve as a novel therapeutic strategy for HCC.

A novel melanin complex displayed the affinity to HepG2 cell membrane and nucleus

Chitosan-melanin complex from Catharsius molossus L. has proven to possess superior pharmaceutical excipient performance and may be the new source of water-soluble protein-free natural melanin. Herein, it was enzymatically hydrolyzed into the chitooligosaccharide-melanin complex (CMC) whose main chemical units were composed of eumelanin and chitooligosaccharides and showed three-layer structures. Additionally, this biomacromolecule could self-assemble into 40 nm nanoparticles (CMC Nps) in a weakly acidic aqueous solution. Interestingly, CMC displayed strong affinity for cell membrane by binding the phosphatidylserine, glycoprotein, glycolipids and glycosaminoglycans accumulated on the surface of tumor cells, notably, CMC Nps could enter cells and mainly target the nucleus by interacting with DNA and/or RNA substrates located around the nucleus to disrupt the proliferation and apoptosis processes. The findings suggest CMC may be the novel material for subcellular organelle targeting of cancer cells.

Transient deSUMOylation of IRF2BP proteins controls early transcription in EGFR signaling

Molecular switches are essential modules in signaling networks and transcriptional reprogramming. Here, we describe a role for small ubiquitin‐related modifier SUMO as a molecular switch in epidermal growth factor receptor (EGFR) signaling. Using quantitative mass spectrometry, we compare the endogenous SUMO proteomes of HeLa cells before and after EGF stimulation. Thereby, we identify a small group of transcriptional coregulators including IRF2BP1, IRF2BP2, and IRF2BPL as novel players in EGFR signaling. Comparison of cells expressing wild type or SUMOylation‐deficient IRF2BP1 indicates that transient deSUMOylation of IRF2BP proteins is important for appropriate expression of immediate early genes including dual specificity phosphatase 1 (DUSP1, MKP‐1) and the transcription factor ATF3. We find that IRF2BP1 is a repressor, whose transient deSUMOylation on the DUSP1 promoter allows—and whose timely reSUMOylation restricts—DUSP1 transcription. Our work thus provides a paradigm how comparative SUMO proteome analyses serve to reveal novel regulators in signal transduction and transcription.

Circ0106714 inhibits tumorigenesis of colorectal cancer by sponging miR-942-5p and releasing DLG2 via Hippo-YAP signaling

This study aimed to investigate the role of circ0106714-miR-942-5p-discs large homolog 2 (DLG2), a novel interactome, in colorectal cancer (CRC). Circ0106714 was found to be the most significantly downregulated circular RNA in CRC using a bioinformatics method, and we researched whether the ability of circ0106714 to sponge miR-942-5p and release DLG2 could affect CRC development via Hippo-YES-associated protein (YAP) signaling. We first employed qRT-PCR and immunoblotting to detect messenger RNA (mRNA) and protein expression, respectively. Live imaging of mice tumor xenografts was then conducted to study the effect of circ0106714 on tumor progression in vivo. Reporter gene assays were subsequently conducted to verify the predicted targeting relationship between circ0106714, miR-942-5p, and DLG2 mRNA in SW480 and HCT116 cell lines. As well as using flow cytometry for both apoptosis and cell cycle profile analyses, CCK-8 and clone foci formation assays were performed to assess cell survival. Wound healing assay and transwell invasion assay were later carried out to evaluate the migration and invasion of the cell lines. Findings revealed that circ0106714 and DLG2 were significantly downregulated, while miR-942-5p was significantly upregulated in human CRC tissues and cell lines. However, circ0106714 upregulation significantly suppressed tumor progression in vivo and inhibited the malignancy phenotypes of tumor cells in vitro by targeting miR-942-5p. Also discovered in this research was that miR-942-5p could directly target DLG2 mRNA, thus enhancing the malignancy phenotypes of CRC cells. We even found that DLG2 overexpression resulted in enhanced phosphorylation of YAP, a critical downstream effector of DLG2. This downstream effector was demonstrated to have a tumor-suppressive capacity in CRC cell lines. In sum, circ0106714 could suppress CRC by sponging miR-942-5p and releasing DLG2, thus promoting YAP phosphorylation.

LncRNA MNX1-AS1 promotes progression of intrahepatic cholangiocarcinoma through the MNX1/Hippo axis

Long non-coding RNAs (lncRNAs) have extremely complex roles in the progression of intrahepatic cholangiocarcinoma (ICC) and remain to be elucidated. By cytological and animal model experiments, this study demonstrated that the expression of lncRNA MNX1-AS1 was remarkably elevated in ICC cell lines and tissues, and was highly and positively correlated with motor neuron and pancreas homeobox protein 1 (MNX1) expression. MNX1-AS1 significantly facilitated the proliferation, migration, invasion, and angiogenesis in ICC cells in vitro, and remarkably promoted tumor growth and metastasis in vivo. Further study revealed that MNX1-AS1 promoted the expression of MNX1 via recruiting transcription factors c-Myc and myc-associated zinc finger protein (MAZ). Furthermore, MNX1 upregulated the expression of Ajuba protein via binding to its promoter region, and subsequently, Ajuba protein suppressed the Hippo signaling pathway. Taken together, our results uncovered that MNX1-AS1 can facilitate ICC progression via MNX1-AS1/c-Myc and MAZ/MNX1/Ajuba/Hippo pathway, suggesting that MNX1-AS1 may be able to serve as a potential target for ICC treatment.

Multiple Roles of Vestigial-Like Family Members in Tumor Development

Vestigial-like family (VGLL) members are mammalian orthologs of vestigial gene in Drosophila, and they consist of four homologs (VGLL1–4). VGLL members have TDU motifs that are binding regions to TEA/ATSS-DNA-binding domain transcription factor (TEAD). Through TDU motifs, VGLL members act as transcriptional cofactors for TEAD. VGLL1-3 have single TDU motif, whereas VGLL4 has two tandem TDU motifs, suggesting that VGLL4 has distinct molecular functions among this family. Although molecular and physiological functions of VGLL members are still obscure, emerging evidence has shown that these members are involved in tumor development. Gene alterations and elevated expression of VGLL1-3 were observed in various types of tumors, and VGLL1-3 have been shown to possess tumorigenic functions. In contrast, down-regulation of VGLL4 was detected in various tumors, and the tumor-suppressing role of VGLL4 has been demonstrated. In this review, we summarize the recently identified multiple roles of VGLL members in tumor development and provide important and novel insights regarding tumorigenesis.

Pits and CtBP Control Tissue Growth in Drosophila melanogaster with the Hippo Pathway Transcription Repressor Tgi

The Hippo pathway is an evolutionarily conserved signaling network that regulates organ size, cell fate, and tumorigenesis. In the context of organ size control, the pathway incorporates a large variety of cellular cues, such as cell polarity and adhesion, into an integrated transcriptional response. The central Hippo signaling effector is the transcriptional coactivator Yorkie, which controls gene expression in partnership with different transcription factors, most notably Scalloped. When it is not activated by Yorkie, Scalloped can act as a repressor of transcription, at least in part due to its interaction with the corepressor protein Tgi. The mechanism by which Tgi represses transcription is incompletely understood, and therefore we sought to identify proteins that potentially operate together with Tgi. Using an affinity purification and mass-spectrometry approach we identified Pits and CtBP as Tgi-interacting proteins, both of which have been linked to transcriptional repression. Both Pits and CtBP were required for Tgi to suppress the growth of the Drosophila melanogaster eye and CtBP loss suppressed the undergrowth of yorkie mutant eye tissue. Furthermore, as reported previously for Tgi, overexpression of Pits repressed transcription of Hippo pathway target genes. These findings suggest that Tgi might operate together with Pits and CtBP to repress transcription of genes that normally promote tissue growth. The human orthologs of Tgi, CtBP, and Pits (VGLL4, CTBP2, and IRF2BP2) have previously been shown to physically and functionally interact to control transcription, implying that the mechanism by which these proteins control transcriptional repression is conserved throughout evolution.

Effect of Diphtheria Toxin-Based Gene Therapy for Hepatocellular Carcinoma

Hepatocellular carcinoma (HCC) is a major global malignancy, responsible for >90% of primary liver cancers. Currently available therapeutic options have poor performances due to the highly heterogeneous nature of the tumor cells; recurrence is highly probable, and some patients develop resistances to the therapies. Accordingly, the development of a novel therapy is essential. We assessed gene therapy for HCC using a diphtheria toxin fragment A (DTA) gene-expressing plasmid, utilizing a non-viral hydrodynamics-based procedure. The antitumor effect of DTA expression in HCC cell lines (and alpha-fetoprotein (AFP) promoter selectivity) is assessed in vitro by examining HCC cell growth. Moreover, the effect and safety of the AFP promoter-selective DTA expression was examined in vivo using an HCC mice model established by the hydrodynamic gene delivery of the yes-associated protein (YAP)-expressing plasmid. The protein synthesis in DTA transfected cells is inhibited by the disappearance of tdTomato and GFP expression co-transfected upon the delivery of the DTA plasmid; the HCC cell growth is inhibited by the expression of DTA in HCC cells in an AFP promoter-selective manner. A significant inhibition of HCC occurrence and the suppression of the tumor marker of AFP and des-gamma-carboxy prothrombin can be seen in mice groups treated with hydrodynamic gene delivery of DTA, both 0 and 2 months after the YAP gene delivery. These results suggest that DTA gene therapy is effective for HCC.

Gene Therapy for Liver Cancers: Current Status from Basic to Clinics

The liver is a key organ for metabolism, protein synthesis, detoxification, and endocrine function, and among liver diseases, including hepatitis, cirrhosis, malignant tumors, and congenital disease, liver cancer is one of the leading causes of cancer-related deaths worldwide. Conventional therapeutic options such as embolization and chemotherapy are not effective against advanced-stage liver cancer; therefore, continuous efforts focus on the development of novel therapeutic options, including molecular targeted agents and gene therapy. In this review, we will summarize the progress toward the development of gene therapies for liver cancer, with an emphasis on recent clinical trials and preclinical studies.