Functional loss of ERBB receptor feedback inhibitor 1 (MIG6) promotes glioblastoma tumorigenesis by aberrant activation of epidermal growth factor receptor (EGFR).

Dysregulation of epidermal growth factor receptor (EGFR) is one of the most common mechanisms associated with the pathogenesis of various cancers. Mitogen-inducible gene 6 [MIG6; also known as ERBB receptor feedback inhibitor 1 (ERRFI1)], identified as a feedback inhibitor of EGFR, negatively regulates EGFR by directly inhibiting its kinase activity and facilitating its internalization, subsequently leading to degradation. Despite its proposed role as an EGFR-dependent tumor suppressor, the functional consequences and clinical relevance in cancer etiology remain incompletely understood. Here, we identify that the stoichiometric balance between MIG6 and EGFR is crucial in promoting EGFR-dependent oncogenic growth in various experimental model systems. In addition, a subset of ERRFI1 (the official gene symbol of MIG6) mutations exhibit impaired ability to suppress the enzymatic activation of EGFR at multiple levels. In summary, our data suggest that decreased or loss of MIG6 activity can lead to abnormal activation of EGFR, potentially contributing to cellular transformation. We propose that the mutation status of ERRFI1 and the expression levels of MIG6 can serve as additional biomarkers for guiding EGFR-targeted cancer therapies, including glioblastoma.

Selumetinib overcomes gefitinib primary and acquired resistance by regulating MIG6/STAT3 in NSCLC.

Gefitinib, as the first-generation epidermal growth factor receptor tyrosine kinase inhibitor (EGFR-TKI), has achieved great advances in the treatment of non-small cell lung cancer (NSCLC), but drug resistance will inevitably occur. Therefore, exploring the resistance mechanism of gefitinib and developing new combination treatment strategies are of great importance. In our study, the results showed that selumetinib (AZD6244) synergistically inhibited the proliferation of NSCLC with gefitinib. Selumetinib also enhanced gefitinib-induced apoptosis and migration inhibition ability in gefitinib-resistant lung cancer cell lines. Subsequently, the negative regulation between MIG6 and STAT3 was observed and verified through the STRING database and western blotting assays. Sustained activation of STAT3 was significantly downregulated when co-treatment with selumetinib in gefitinib-resistant cells. However, the downregulation of p-STAT3, resulting from the combination of selumetinib and gefitinib was counteracted by the deletion of MIG6, suggesting that selumetinib enhanced gefitinib sensitivity by regulating MIG6/STAT3 in NSCLC. In contrast, p-STAT3 was further inhibited after treatment with gefitinib and selumetinib when MIG6 was overexpressed. Furthermore, the combined administration of selumetinib and gefitinib effectively promoted the sensitivity of lung cancer xenografts to gefitinib in vivo, and the tumor inhibition rate reached 81.49%, while the tumor inhibition rate of the gefitinib monotherapy group was only 31.95%. Overall, MIG6/STAT3 negative regulation plays an important role in the sustained activation of STAT3 and the resistance to EGFR-TKIs. Our study also suggests that EGFR-TKIs combined with MEK1/2 inhibitors, such as selumetinib, may be beneficial to those NSCLC patients who develop a primary or acquired resistance to EGFR-TKIs, providing theoretical support for combining TKIs and selumetinib in clinical cancer treatment.

Intervention of AXL in EGFR Signaling via Phosphorylation and Stabilization of MIG6 in Non-Small Cell Lung Cancer.

About 80% of lung cancer patients are diagnosed with non-small cell lung cancer (NSCLC). EGFR mutation and overexpression are common in NSCLC, thus making EGFR signaling a key target for therapy. While EGFR kinase inhibitors (EGFR-TKIs) are widely used and efficacious in treatment, increases in resistance and tumor recurrence with alternative survival pathway activation, such as that of AXL and MET, occur frequently. AXL is one of the EMT (epithelial-mesenchymal transition) signature genes, and EMT morphological changes are also responsible for EGFR-TKI resistance. MIG6 is a negative regulator of ERBB signaling and has been reported to be positively correlated with EGFR-TKI resistance, and downregulation of MIG6 by miR-200 enhances EMT transition. While MIG6 and AXL are both correlated with EMT and EGFR signaling pathways, how AXL, MIG6 and EGFR interplay in lung cancer remains elusive. Correlations between AXL and MIG6 expression were analyzed using Oncomine or the CCLE. A luciferase reporter assay was used for determining MIG6 promoter activity. Ectopic overexpression, RNA interference, Western blot analysis, qRT-PCR, a proximity ligation assay and a coimmunoprecipitation assay were performed to analyze the effects of certain gene expressions on protein-protein interaction and to explore the underlying mechanisms. An in vitro kinase assay and LC-MS/MS were utilized to determine the phosphorylation sites of AXL. In this study, we demonstrate that MIG6 is a novel substrate of AXL and is stabilized upon phosphorylation at Y310 and Y394/395 by AXL. This study reveals a connection between MIG6 and AXL in lung cancer. AXL phosphorylates and stabilizes MIG6 protein, and in this way EGFR signaling may be modulated. This study may provide new insights into the EGFR regulatory network and may help to advance cancer treatment.

Prognostic Value of Erythroblastic Leukemia Viral Oncogene Homolog 2 and Neuregulin 4 in Hepatocellular Carcinoma.

Although the roles of erythroblastic leukemia viral oncogene homolog 2 (ERBB2), neuregulin 4 (NRG4), and mitogen-inducible gene 6 (MIG6) in epidermal growth factor receptor signaling in hepatocellular carcinoma (HCC) and other malignancies have been previously investigated, the prognostic value of their serum levels in HCC remains undetermined. In the present study, correlations between serum levels and tumor characteristics, overall survival, and tumor recurrence were analyzed. Furthermore, the prognostic potential of the serum levels of these biomarkers was evaluated relative to that of alpha-fetoprotein. Both ERBB2 and NRG4 correlated with the Barcelona Clinic Liver Cancer stage, ERBB2 correlated with the tumor-maximal diameter, and NRG4 correlated with a tumor number. Cox proportional hazards regression analysis revealed that ERBB2 (hazard ratio [HR], 2.719; p = 0.007) was an independent prognostic factor for overall survival. Furthermore, ERBB2 (HR, 2.338; p = 0.002) and NRG4 (HR, 431.763; p = 0.001) were independent prognostic factors for tumor recurrence. The products of ERBB2 and NRG4 had a better area under the curve than alpha-fetoprotein for predicting 6-month, 1-year, 3-year, and 5-year mortality. Therefore, these factors could be used to evaluate prognosis and monitor treatment response in patients with HCC.

The Adaptor Protein NumbL Is Involved in the Control of Glucolipotoxicity-Induced Pancreatic Beta Cell Apoptosis.

Avoiding the loss of functional beta cell mass is critical for preventing or treating diabetes. Currently, the molecular mechanisms underlying beta cell death are partially understood, and there is a need to identify new targets for developing novel therapeutics to treat diabetes. Previously, our group established that Mig6, an inhibitor of EGF signaling, mediates beta cell death under diabetogenic conditions. The objective here was to clarify the mechanisms linking diabetogenic stimuli to beta cell death by investigating Mig6-interacting proteins. Using co-immunoprecipitation and mass spectrometry, we evaluated the binding partners of Mig6 under both normal glucose (NG) and glucolipotoxic (GLT) conditions in beta cells. We identified that Mig6 interacted dynamically with NumbL, whereas Mig6 associated with NumbL under NG, and this interaction was disrupted under GLT conditions. Further, we demonstrated that the siRNA-mediated suppression of NumbL expression in beta cells prevented apoptosis under GLT conditions by blocking the activation of NF-κB signaling. Using co-immunoprecipitation experiments, we observed that NumbL's interactions with TRAF6, a key component of NFκB signaling, were increased under GLT conditions. The interactions among Mig6, NumbL, and TRAF6 were dynamic and context-dependent. We proposed a model wherein these interactions activated pro-apoptotic NF-κB signaling while blocking pro-survival EGF signaling under diabetogenic conditions, leading to beta cell apoptosis. These findings indicated that NumbL should be further investigated as a candidate anti-diabetic therapeutic target.

Critical role of mitogen-inducible gene 6 in restraining endothelial cell permeability to maintain vascular homeostasis.

Although mitogen-inducible gene 6 (MIG6) is highly expressed in vascular endothelial cells, it remains unknown whether MIG6 affects vascular permeability. Here, we show for the first time a critical role of MIG6 in limiting vascular permeability. We unveil that genetic deletion of Mig6 in mice markedly increased VEGFA-induced vascular permeability, and MIG6 knockdown impaired endothelial barrier function. Mechanistically, we reveal that MIG6 inhibits VEGFR2 phosphorylation by binding to the VEGFR2 kinase domain 2, and MIG6 knockdown increases the downstream signaling of VEGFR2 by enhancing phosphorylation of PLCγ1 and eNOS. Moreover, MIG6 knockdown disrupted the balance between RAC1 and RHOA GTPase activation, leading to endothelial cell barrier breakdown and the elevation of vascular permeability. Our findings demonstrate an essential role of MIG6 in maintaining endothelial cell barrier integrity and point to potential therapeutic implications of MIG6 in the treatment of diseases involving vascular permeability. Xing et al. (2022) investigated the critical role of MIG6 in vascular permeability. MIG6 deficiency promotes VEGFA-induced vascular permeability via activation of PLCγ1-Ca2+-eNOS signaling and perturbation of the balance in RAC1/RHOA activation, resulting in endothelial barrier disruption.

MIG-6 Is Critical for Progesterone Responsiveness in Human Complex Atypical Hyperplasia and Early-Stage Endometrial Cancer.

Women with complex atypical hyperplasia (CAH) or early-stage endometrioid endometrial cancer (EEC) are candidates for fertility preservation. The most common approach is progesterone (P4) therapy and deferral of hysterectomy until after completion of childbearing. However, P4 therapy response rates vary, and molecular mechanisms behind P4 resistance are poorly understood. One potential molecular cause of P4 resistance is a loss or attenuation of PGR expression. Mitogen-inducible gene 6 (MIG-6) is critical for P4 responsiveness. MIG-6 protein expression in the endometrial epithelial and stromal cells from women with CAH and EEC was significantly lower compared to women without CAH or EEC. The P4-responsive women (10/15) exhibited an increase of MIG-6 expression in epithelial and stromal cells compared to P4-resistant women (5/15). In addition, immunohistochemical analysis for PGR results showed that stromal PGR levels are significantly higher in P4-responsive women compared to P4-resistant women, whereas epithelial PGR expression was not different. A reverse correlation of MIG-6 and pAKT levels was observed in early-stage EEC patients. Studies strongly suggest that loss of MIG-6 and PGR and activation of pAKT lead to P4 resistance in CAH and EEC. These results will help to elucidate the molecular mechanism leading to P4 resistance in CAH and EEC.

Mig-6 Inhibits Autophagy in HCC Cell Lines by Modulating miR-193a-3p.

Mitogen-inducible gene 6 (Mig-6) is a tumor suppressor gene that plays an important role in many types of cancers by interacting with EGFR. However, its molecular mechanism in hepatocellular carcinoma (HCC) and its relationship with miRNAs need to be elucidated. Therefore, this study aimed to explore whether Mig-6 could promote apoptosis and the inhibition of autophagy via its downstream miRNA in HCC cell lines. We used two cell lines, HepG2 and HLE, to establish Mig-6 overexpression and knockdown experiments, as well as miR-193a mimic and inhibitor experiments. The miRNA microarray profiling was also used to verify Mig-6-regulated miRNA. We found that Mig-6 induced apoptosis and reduced autophagy of HCC cell lines. miR-193a-3p is a Mig-6-regulated miRNA in the Mig-6-overexpression model. It affected the apoptosis and autophagy of HCC cells, at least partly by regulating the expression of TGF-ß2. Additionally, the relationship between Mig-6 and transforming growth factor TGF-ß2 was explored in depth for the first time. These findings revealed an important role of Mig-6 in the apoptosis and autophagy of HCC cells by regulating miR-193a-3p, providing a novel insight into the therapeutic target in HCC.

Effect of Gene 33/Mig6/ERRFI1 on hexavalent chromium-induced transformation of human bronchial epithelial cells depends on the length of exposure.

Hexavalent chromium (Cr(VI)) compounds are environmental and occupational lung carcinogens. The present study followed the chronic effect of Cr(VI) on the neoplastic transformation of BEAS-2B lung bronchial epithelial cells with or without deletion of Gene 33 (Mig6, EFFRI1), a multifunctional adaptor protein. We find that Gene 33-deleted cells exhibit increased anchorage-independent growth compared to control cells after transformed by 8-week but not 24-week Cr(VI) exposure. Gene 33-deleted cells show a higher level of cell proliferation and are more resistant to acute Cr(VI) toxicity compared to control cells after transformed by 8-week but not 24-week Cr(VI) exposure, despite that 24-week-transformed cells have increased resistance to acute Cr(VI) toxicity. However, Gene 33-deleted cells show increased migration after transformed by both 8-week and 24-week Cr(VI) exposures. Furthermore, only cells transformed by 24 weeks of Cr(VI) exposure can form subcutaneous tumors in nude mice. Although no significant difference in the size of tumors formed by the two cell types, there is a marked difference in the histological manifestation and more MMP3 expression in tumors from Gene 33-deleted cells. Our results demonstrate progressive neoplastic transformation of BEAS-2B cells and the adaptation of these cells to Gene 33 deletion during chronic exposure to Cr(VI).

Mig-6 could inhibit cell proliferation and induce apoptosis in esophageal squamous cell carcinoma.

BACKGROUND: To investigate the expression and biological functions of mitogen-induced gene 6 (Mig-6) in esophageal squamous cell carcinoma (ESCC). METHODS: The expression of Mig-6 in ESCC tissues and normal esophageal epithelial tissues were measured by immunohistochemistry (IHC) assay. MTT test was applied to detect the proliferative ability of ESCC cells after Mig-6 was upregulated by transfection. A fluid cytology assay was used to detect apoptosis of ESCC cells. Agilent whole human genome oligo microarray was used to screen different expressed genes and the possible signaling pathways which might be involved. RESULTS: The expression of Mig-6 protein was lower in ESCC tissues compared to normal esophageal epithelial tissues. Mig-6 could restrain the ESCC cell growth and induce cell apoptosis. PPAR, CAMs and MAPK signaling pathways might be involved. CONCLUSIONS: Mig-6 might be a new tumor suppressor gene and a possible target for the specific therapy of ESCC.

Mig-6 is essential for glucose homeostasis and thermogenesis in brown adipose tissue.

Brown adipose tissue (BAT) is an anti-obese and anti-diabetic tissue that stimulates energy expenditure in the form of adaptive thermogenesis through uncoupling protein 1 (UCP1). Mitogen-inducible gene-6 (Mig-6) is a negative regulator of epidermal growth factor receptor (EGFR) that interacts with many cellular partners and has multiple cellular functions. We have recently reported that Mig-6 is associated with diabetes and metabolic syndrome. However, its function in BAT is unknown. We generated a brown adipocyte-specific Mig-6 knock-in mouse (BKI) to examine the role of Mig-6 in BAT. Mig-6 BKI mice had improved glucose tolerance on a normal chow diet. Mig-6 BKI mice also revealed activated thermogenesis and the size of the BAT lipid droplets was reduced. Additionally, Mig-6 regulated cAMP-PKA signaling-induced UCP1 expression in brown adipocytes. Taken together, these results demonstrate that Mig-6 affects glucose tolerance and thermogenesis in BAT.

Honokiol Prevents Non-Alcoholic Steatohepatitis-Induced Liver Cancer via EGFR Degradation through the Glucocorticoid Receptor-MIG6 Axis.

Non-alcoholic steatohepatitis (NASH) has become a serious public health problem associated with metabolic syndrome. The mechanisms by which NASH induces hepatocellular carcinoma (HCC) remain unknown. There are no approved drugs for treating NASH or preventing NASH-induced HCC. We used a genetic mouse model in which HCC was induced via high-fat diet feeding. This mouse model strongly resembles human NASH-induced HCC. The natural product honokiol (HNK) was tested for its preventative effects against NASH progression to HCC. Then, to clarify the mechanisms underlying HCC development, human HCC cells were treated with HNK. Human clinical specimens were also analyzed to explore this study's clinical relevance. We found that epidermal growth factor receptor (EGFR) signaling was hyperactivated in the livers of mice with NASH and human HCC specimens. Inhibition of EGFR signaling by HNK drastically attenuated HCC development in the mouse model. Mechanistically, HNK accelerated the nuclear translocation of glucocorticoid receptor (GR) and promoted mitogen-inducible gene 6 (MIG6)/ERBB receptor feedback inhibitor 1 (ERRFI1) expression, leading to EGFR degradation and thereby resulting in robust tumor suppression. In human samples, EGFR-positive HCC tissues and their corresponding non-tumor tissues exhibited decreased ERRFI1 mRNA expression. Additionally, GR-positive non-tumor liver tissues displayed lower EGFR expression. Livers from patients with advanced NASH exhibited decreased ERRFI1 expression. EGFR degradation or inactivation represents a novel approach for NASH-HCC treatment and prevention, and the GR-MIG6 axis is a newly defined target that can be activated by HNK and related compounds.

Mitogen-Inducible Gene 6 Inhibits Angiogenesis by Binding to SHC1 and Suppressing Its Phosphorylation.

The mitogen-inducible gene 6 (MIG6) is an adaptor protein widely expressed in vascular endothelial cells. However, it remains unknown thus far whether it plays a role in angiogenesis. Here, using comprehensive in vitro and in vivo model systems, we unveil a potent anti-angiogenic effect of MIG6 in retinal development and neovascularization and the underlying molecular and cellular mechanisms. Loss of function assays using genetic deletion of Mig6 or siRNA knockdown increased angiogenesis in vivo and in vitro, while MIG6 overexpression suppressed pathological angiogenesis. Moreover, we identified the cellular target of MIG6 by revealing its direct inhibitory effect on vascular endothelial cells (ECs). Mechanistically, we found that the anti-angiogenic effect of MIG6 is fulfilled by binding to SHC1 and inhibiting its phosphorylation. Indeed, SHC1 knockdown markedly diminished the effect of MIG6 on ECs. Thus, our findings show that MIG6 is a potent endogenous inhibitor of angiogenesis that may have therapeutic value in anti-angiogenic therapy.

MIG-6 is essential for promoting glucose metabolic reprogramming and tumor growth in triple-negative breast cancer.

Treatment of triple-negative breast cancer (TNBC) remains challenging due to a lack of effective targeted therapies. Dysregulated glucose uptake and metabolism are essential for TNBC growth. Identifying the molecular drivers and mechanisms underlying the metabolic vulnerability of TNBC is key to exploiting dysregulated cancer metabolism for therapeutic applications. Mitogen-inducible gene-6 (MIG-6) has long been thought of as a feedback inhibitor that targets activated EGFR and suppresses the growth of tumors driven by constitutive activated mutant EGFR. Here, our bioinformatics and histological analyses uncover that MIG-6 is upregulated in TNBC and that MIG-6 upregulation is positively correlated with poorer clinical outcomes in TNBC. Metabolic arrays and functional assays reveal that MIG-6 drives glucose metabolism reprogramming toward glycolysis. Mechanistically, MIG-6 recruits HAUSP deubiquitinase for stabilizing HIF1α protein expression and the subsequent upregulation of GLUT1 and other HIF1α-regulated glycolytic genes, substantiating the comprehensive regulation of MIG-6 in glucose metabolism. Moreover, our mouse studies demonstrate that MIG-6 regulates GLUT1 expression in tumors and subsequent tumor growth in vivo. Collectively, this work reveals that MIG-6 is a novel prognosis biomarker, metabolism regulator, and molecular driver of TNBC.

Suppression of Mig-6 overcomes the acquired EGFR-TKI resistance of lung adenocarcinoma.

BACKGROUND: The resistance of lung cancer to epidermal growth factor receptor-tyrosine kinase inhibitor (EGFR-TKI) is one of the unconquered frontiers in chemotherapy. Mitogen-inducible gene 6 (Mig-6) is known to inhibit the kinase activity of epidermal growth factor receptor (EGFR). Similarly, numerous studies of mouse models suggested tumor suppressive function of Mig-6 in lung cancer. On the contrary, the results of clinical investigations revealed that lung cancer patients with elevated expression of Mig-6 are associated with a poor prognosis. More recent work showed that unlike wild type (WT) EGFR, mutant EGFR phosphorylates Mig-6 and phosphorylated Mig-6 negatively regulates the degradation of EGFR mutants in lung adenocarcinoma. Here, we tried to untangle the controversies surrounding Mig-6 function as a protagonist or an antagonist of EGFR-TKI resistant lung cancer. METHODS: We compared the expression and phosphorylation status of Mig-6 in the EGFR-TKI resistant lung adenocarcinoma (PC9/GR cells) to EGFR-TKI sensitive lung adenocarcinoma (PC9 cells). We investigated the function of Mig-6 by either depletion or overexpression of Mig-6 in those cells and evaluated the efficacy of combining of Mig-6 knock-down and EGFR-TKI treatment in PC9/GR. The correlation between Mig-6 expressions and the prognoses of lung adenocarcinoma was examined by The Cancer Genome Atlas (TCGA) data and clinical samples. RESULTS: Our results indicated that the expression of Mig-6 was significantly increased in PC9/GR cells compared to that of PC9 cells. The significant portion of Mig-6 existed as a phosphorylated form in PC9 and PC9/GR cells. Moreover, overexpression of Mig-6 significantly increased the cell proliferation, invasion and epithelial mesenchymal transition (EMT) in PC9 cells. Combination of Mig-6 knock-down and EGFR-TKI treatment significantly overcame the EGFR-TKI resistance of PC9/GR cells. In addition, our analyses of clinical samples confirmed that high Mig-6 expressions positively correlate with a poor prognosis and EGFR-TKI resistance in lung adenocarcinoma. CONCLUSION: Our findings reinforce scientific notion of Mig-6 as an oncoprotein in the context of EGFR-TKI resistant lung adenocarcinoma. We propose that targeting Mig-6 may be a promising strategy to overcome the EGFR-TKI resistance in lung cancer.

Making sense of Cbp/p300 loss of function mutations in skin tumorigenesis.

CBP and p300 are highly homologous lysine acetyltransferases involved in cell cycle regulation, DNA synthesis and DNA repair. Loss of function mutations of CBP and p300 are found in about one-third of cutaneous squamous cell carcinoma (cSCC) and often co-occur, yet their role in cSCC pathogenesis is unclear. Writing in The Journal of Pathology, Ichise and colleagues modeled combined heterozygous loss of Cbp/p300 in mouse keratinocytes expressing a transgenic HrasS35 allele that allows selective coupling of Hras to the Erk pathway. Epidermal thickening caused by expression of HrasS35 was exacerbated by reduced dosage of Cbp/p300 and eventually resulted in development of skin papillomas. This phenotype was associated with reduced expression of Mig6, an Egfr feedback inhibitor, and attendant enhancement of Egfr signaling to the Ras-Erk pathway. This model provides a mechanistic framework for understanding how Cbp/p300 loss of function mutations impact on skin tumorigenesis and suggests potential therapeutic options in CBP/p300 mutated human cSCC. © 2019 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.

Lung cancer stem cells and their aggressive progeny, controlled by EGFR/MIG6 inverse expression, dictate a novel NSCLC treatment approach.

The lung cancer stem cell (LuCSC) model comprises an attractive framework to explore acquired drug resistance in non-small cell lung cancer (NSCLC) treatment. Here, we used NSCLC cell line model to translate cellular heterogeneity into tractable populations to understand the origin of lung cancers and drug resistance. The epithelial LuCSCs, presumably arising from alveolar bipotent stem/progenitor cells, were lineage naïve, noninvasive, and prone to creating aggressive progeny expressing AT2/AT1 markers. LuCSC-holoclones were able to initiate rimmed niches, where their specialization created pseudo-alveoli structures. Mechanistically, LuCSC transitioning from self-renewal (ß-catenin and Nanog signaling) to malignant lineage differentiation is regulated by EGFR activation and the inverse inhibition of tumor suppressor MIG6. We further identified the functional roles of endogenous EGFR signaling in mediating progeny invasiveness and their ligands in LuCSC differentiation. Importantly, drug screening demonstrated that EGFR driving progeny were strongly responsive to TKIs; however, the LuCSCs were exclusively resistant but sensitive to AMPK agonist Metformin, antibiotic Salinomycin and to a lesser degree Carboplatin. Our data reveals previously an unknown mechanism of NSCLC resistance to EGFR-TKIs, which is associated with LuCSCs bearing a silenced EGFR and inversely expressed MIG6 suppressor gene. Taken altogether, successful NSCLC treatment requires development of a novel combination of drugs, efficiently targeting both LuCSCs and heterogeneous progeny.

CBP/p300 antagonises EGFR-Ras-Erk signalling and suppresses increased Ras-Erk signalling-induced tumour formation in mice.

CREB-binding protein (CBP) and p300 have oncogenic properties; both co-operate with pro-oncogenic transcription factors downstream of Ras-Erk signalling to support cell proliferation. By contrast, missense, truncating and in-frame mutations of CBP/p300 are found frequently in some human cancers, including cutaneous squamous cell carcinomas that originate from epidermal keratinocytes. Data support that dysfunction of CBP/p300 contributes to keratinocyte hyperproliferation and tumourigenesis; however, the mechanism by which dysfunction of CBP/p300 affects keratinocytes is unknown. Here, we used mice harbouring keratinocyte-specific genetic modifications to examine the role of CBP/p300 in the epidermis. While a single copy of either Crebbp or Ep300 was necessary and sufficient for maintaining epidermal development, reduced expression of CBP/p300 strengthened the Ras-Erk signalling-induced hyperplastic phenotype of epidermal keratinocytes. Reduced CBP/p300 expression increased ligand-induced EGFR activity while decreasing basal expression of Mig6, a negative regulator of EGFR. A reduction in CBP/p300, in combination with increased Ras-Erk signalling, also promoted epidermal tumour formation in mice. Thus, our findings support that CBP/p300 acts as a tumour suppressor in epidermal keratinocytes by counteracting EGFR-Ras-Erk signalling. © 2019 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.

AAV-Mig-6 Increase the Efficacy of TAE in VX2 Rabbit Model, Is Associated With JNK Mediated Autophagy.

The characterization of high recurrence rate of HCC after TAE provides insights into persistent issues surrounding the role of adjunct therapies administered with TAE. As a regulator of the HER family, Mig-6 is down-regulated in HCC and predicts the prognosis of HCC. In this study, we found up-regulation the expression of Mig-6 enhances autophagy in HCC cells. This function of Mig-6 is related to the activation of the JNK pathway. Next AAV-9 encoding Mitogen inducible gene 6 (Mig-6) was delivered into VX2 liver transplant tumor of rabbits by using hepatic artery catheter. Wild-type AAV is not associated with any human or animal disease and has very low immunogenicity. There are over 100 different AAV serotypes that vary in the amino acid sequence of their capsid protein. We also describe a novel combination therapy coupling AAV-Mig-6 and TAE in a rabbit model resulted in a growth rate decrease in tumor compared with TAE alone. Furthermore, we show that the changes of LC3b and p62, as well as the p-JNK were consistent with changes in vitro experiments. These results suggest that Mig-6 efficiently inhibits tumor progression in vivo. Our findings suggest that Mig-6 induced autophagy inhibition may become a necessary target for adjunct therapy in TAE.

A calcium-dependent phospholipase A2 (cPLA2) expression is regulated by MIG-6 during endometrial tumorigenesis.

The ovarian steroid hormones, estrogen (E2) and progesterone (P4), are essential regulators of uterine biology. The imbalance of these ovarian steroid hormones leads to uterine diseases such as endometrial cancer, endometriosis, and infertility. Mitogen-inducible gene 6 (MIG-6) is an adaptor protein. MIG-6 mediates P4 signaling and acts as a tumor suppressor during endometrial tumorigenesis in both humans and mice. In previous studies, we developed the conditional knockout of Mig-6 in all uterine compartments (Pgrcre/+Mig-6f/f; Mig-6KO) and endometrial epithelial cell-specific Mig-6 knockout (Sprr2fcre/+Mig-6f/f; Mig-6Ep-KO) mice. Both mouse models developed endometrial hyperplasia and E2-dependent endometrial cancer. P4 treatment significantly decreases aberrant epithelial proliferation and AKT signaling in Mig-6Ep-KO mice but not in Mig-6KO mice. In the present study, we identified a calcium-dependent phospholipase A2 (cPla2) as one of the genes down-regulated by Mig-6 in the uterus. We performed immunohistochemistry and Western Blot analysis to investigate the regulation of cPLA2 by MIG-6 as well as determine the expression patterns of cPLA2 in the uterus. While the expression of cPLA2 was stronger at the uterine epithelial cells of Mig-6KO and Mig-6Ep-KO mice compared to control mice, P4 suppressed the expression of cPLA2 in Mig-6Ep-KO mice but not in Mig-6KO mice. To determine the ovarian steroid hormone regulation of cPLA2, we examined the expression of cPLA2 in ovariectomized control, Mig-6KO, Mig-6Ep-KO, and PRKO mice treated with P4 or E2. After P4 treatment, cPLA2 expression was remarkably reduced in Mig-6Ep-KO mice but not in Mig-6KO mice. However, the expression of cPLA2 was not changed in PRKO mice. Our results identified cPLA2 as a novel target of MIG-6 in the murine uterus and identified its important role during endometrial tumorigenesis.