Purpose: Targeting the protein neddylation pathway has become an attractive anticancer strategy; however, the role of death receptor-mediated extrinsic apoptosis during treatment remained to be determined.Experimental Design: The activation of extrinsic apoptosis and its role in MLN4924 treatment of human esophageal squamous cell carcinoma (ESCC) were evaluated both in vitro and in vivo. The expression of the components of extrinsic apoptotic pathway was determined by immunoblotting analysis and downregulated by siRNA silencing for mechanistic studies.Results: Pharmaceutical or genetic inactivation of neddylation pathway induced death receptor 5 (DR5)-mediated apoptosis and led to the suppression of ESCC in murine models. Mechanistically, neddylation inhibition stabilized activating transcription factor 4 (ATF4), a Cullin-Ring E3 ubiquitin ligases (CRL) substrate. Transcription factor CHOP was subsequently transactivated by ATF4 and further induced the expression of DR5 to activate caspase-8 and induce extrinsic apoptosis. Moreover, the entire neddylation pathway was hyperactivated in ESCC and was negatively associated with patient overall survival.Conclusions: Our findings highlight a critical role of ATF4-CHOP-DR5 axis-mediated extrinsic apoptosis in neddylationtargeted cancer therapy and support the clinical investigation of neddylation inhibitors (e.g., MLN4924) for the treatment of ESCC, a currently treatment-resistant disease with neddylation hyperactivation.

Protein S‐palmitoylation (hereinafter referred to as protein palmitoylation) is a reversible lipid posttranslational modification catalyzed by the zinc finger DHHC‐type containing (ZDHHC) protein family. The reverse reaction, depalmitoylation, is catalyzed by palmitoyl‐protein thioesterases (PPTs), including acyl‐protein thioesterases (APT1/2), palmitoyl protein thioesterases (PPT1/2), or alpha/beta hydrolase domain‐containing protein 17A/B/C (ABHD17A/B/C). Proteins encoded by several oncogenes and tumor suppressors are modified by palmitoylation, which enhances the hydrophobicity of specific protein subdomains, and can confer changes in protein stability, membrane localization, protein–protein interaction, and signal transduction. The importance for protein palmitoylation in tumorigenesis has just started to be elucidated in the past decade; palmitoylation appears to affect key aspects of cancer, including cancer cell proliferation and survival, cell invasion and metastasis, and antitumor immunity. Here we review the current literature on protein palmitoylation in the various cancer types, and discuss the potential of targeting of palmitoylation enzymes or palmitoylated proteins for tumor treatment.

Abstract. Although several studies highlight the important role of cAMP-responsive element binding protein (CREB) in tumor progression, little is known concerning the expression and function of CREB in esophageal cancer. In the present study, the expression of CREB was evaluated using a human esophageal squamous cell carcinoma tissue array by immunohistochemical analysis, which was confirmed by western blot analysis of tissues from esophageal cancer, and adjacent esophageal tissue. The role of CREB on esophageal cancer cell growth was analyzed in vitro and in vivo. Results showed that CREB was overexpressed in esophageal squamous cell carcinomas tissues, which was positively correlated with lymph node metastasis and tumor-node-metastasis (TNM) stage of esophageal cancer patients. Downregulating the expression of CREB effectively reduced esophageal cell growth in vitro and in vivo, induced S phase cell cycle arrest, triggered apoptosis and inhibited cell migration and invasion. These findings suggested CREB as an attractive drug target for esophageal cancer.

Meesmann epithelial corneal dystrophy (MECD) is a dominantly inherited disorder, characterized by fragility of the anterior corneal epithelium and formation of intraepithelial microcysts. It has been described in a number of different ancestral groups. To date, all reported cases of MECD have been associated with either a single mutation in one exon of the keratin-3 gene (KRT3) or a single mutation in one of two exons of the keratin-12 gene (KRT12). Each mutation leads to a predicted amino acid change in the respective keratin-3 or keratin-12 proteins that combine to form the corneal-specific heterodimeric intermediate filament protein. This case report describes a four-generation Chinese kindred with typical autosomal-dominant MECD. Exon sequencing of KRT3 and KRT12 in six affected and eight unaffected individuals (including two spouses) did not detect any mutations or nucleotide sequence variants. This kindred demonstrates that single mis-sense mutations may be sufficient but are not required in all individuals with the MECD phenotype. It provides a unique opportunity to investigate further genomic and functional heterogeneity in MECD.

BackgroundPrevious reports showed that Activating Transcription Factor 1 (ATF1) plays an important role in tumor progression in a tumor-specific manner. However, little is known about the expression and role of ATF1 in esophageal cancer.Material/MethodsThe expression of ATF1 was examined by immunohistochemistry and Western blotting. The correlation between the expression of ATF1 and clinical characteristics of esophageal squamous cell carcinomas (ESCC) patients was analyzed by Fisher’s exact test. The role of cell proliferation, clonogenic survival, migration, and invasion in vitro, as well as the sensitization to paclitaxel, were determined after knockdown of ATF1 by siRNA.ResultsATF1 was overexpressed in ESCC tissues, which was positively correlated with lymph node metastasis, poor differentiation, and early tumor invasion of esophageal cancer patients. Knockdown of ATF1 effectively reduced cell proliferation, induced S phase cell cycle arrest, and inhibited cell migration and invasion. Moreover, silencing of ATF1 significantly enhanced the sensitivity of esophageal cancer cells to paclitaxel.ConclusionsThese findings suggest that ATF1 is a promising drug target for esophageal cancer.

Extracellular matrix mineralization is critical for osteogenesis, and its dysregulation could result in osteoporosis and vascular calcification. IKK/NF-κB activation inhibits differentiation of osteoblasts, and reduces extracellular matrix mineralization, however the underlying mechanisms are poorly understood. In this study, we used CRISPR/Cas9 system to permanently inactivate IKKβ in preosteoblast cells and confirmed that such cells displayed dramatic increase in extracellular matrix mineralization associated with JNK phosphorylation. Such observation was also found in our study using IKKβ-deficient primary murine osteoblasts. Interestingly, we found that in Ikbkb −/− Mapk8 −/− or Ikbkb −/− Mapk9 −/− double knockout cells, the enhanced mineralization caused by IKKβ deficiency was completely abolished, and deletion of either Mapk8 or Mapk9 was sufficient to dampen c-Jun phosphorylation. In further experiments, we discovered that absence of JNK1 or JNK2 on IKKβ-deficient background resulted in highly conserved transcriptomic alteration in response to osteogenic induction. Therefore, identification of the indispensable roles of JNK1 and JNK2 in activating c-Jun and promoting osteoblast differentiation on IKKβ-deficient background provided novel insights into restoring homeostasis in extracellular matrix mineralization.

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<p>Supplementary Figure S1. Expression of the global neddylation protein, NEDD8-activating enzyme E1 and NEDD8-conjugating enzyme E2 in ESCC tissues Supplementary Figure S2. Expression of death-receptor family and Bcl-2 family members Supplementary Figure S3. MLN4924 acted on DR5-mediated apoptosis independently of Trail. Kyse450 and EC1 cells were transfected (48 hours) with control or Trail siRNA, treated with 0.6 μM MLN4924 (48 hours). Supplementary Figure S4. MLN4924 inhibited the polyubiquitination modification of ATF4. A, MLN4924 increased the mRNA level of CHOP while little effect on ATF4 mRNA level. Supplementary Figure S5. A, Knockdown efficiency of ATF4. Kyse450 and EC1 cells were transfected with control or ATF4 siRNA for 24 hours and then treated with 0.6 μM MLN4924 for 48 hours Supplementary Figure S6. Genetic inactivation of neddylation pathway via NAE1/UBA3 siRNA silencing recapitulates MLN4924-induced cellular responses in ESCC cells. Supplementary Figure S7. No body weight loss occurred during treatment. Body weight of the animals was measured and recorded during the treatment period.</p>