Toll-like receptor 4 (TLR4) is important in promoting the immune response in various cancers. Recently, TLR4 is highly expressed in a stage-dependent manner in gastric cancer, but the regulatory mechanism of TLR4 expression has been not elucidated it. Here, we investigated the mechanism underlying regulation of TLR4 expression through promoter methylation and histone modification between transcriptional regulation and silencing of the TLR4 gene in gastric cancer cells. Chromatin immunoprecipitation was carried out to screen for factors related to TLR4 methylation such as MeCP2, HDAC1, and Sp1 on the TLR4 promoter. Moreover, DNA methyltransferase inhibitor 5-aza-deoxycytidine (5-aza-dC) induced demethylation of the TLR4 promoter and increased H3K4 trimethylation and Sp1 binding to reactivate silenced TLR4. In contrast, although the silence of TLR4 activated H3K9 trimethylation and MeCP2 complex, combined treatment with TLR4 agonist and 5-aza-dC upregulated H3K4 trimethylation and activated with transcription factors as Sp1 and NF-κB. This study demonstrates that recruitment of the MeCP2/HDAC1 repressor complex increases the low levels of TLR4 expression through epigenetic modification of DNA and histones on the TLR4 promoter, but Sp1 activates TLR4 high expression by hypomethylation and NF-κB signaling in gastric cancer cells.

Cystatin SN (CST1) is a specific inhibitor belonging to the cystatin superfamily that controls the proteolytic activities of cysteine proteases such as cathepsins. Our previous study showed that high CST1 expression enhances tumor metastasis and invasiveness in colorectal cancer. Recently, auranofin (AF), a gold(I)-containing thioredoxin reductase 1 (TrxR1) inhibitor, has been used clinically to treat rheumatoid arthritis. AF is a proteasome-associated deubiquitinase inhibitor and can act as an anti-tumor agent. In this study, we investigated whether CST1 expression induces autophagy and tumor cell survival. We also investigated the therapeutic effects of AF as an anti-tumor agent in colorectal cancer (CRC) cells. We found that CRC cells expressing high levels of CST1 undergo increased autophagy and exhibit chemotherapeutic resistance to AF-induced cell death, while those expressing low levels of CST1 are sensitive to AF. We also observed that knockdown of CST1 in high-CST1 CRC cells using CST1-specific small interfering RNAs attenuated autophagic activation and restored AF-induced cell mortality. Conversely, the overexpression of CST1 increased autophagy and viability in cells expressing low levels of CST1. Interestingly, high expression of CST1 attenuates AF-induced cell death by inhibiting intracellular reactive oxygen species (ROS) generation, as demonstrated by the fact that the blockage of ROS production reversed AF-induced cell death in CRC cells. In addition, upregulation of CST1 expression increased cellular glutathione reductase (GR) activity, reducing the cellular redox state and inducing autophagy in AF-treated CRC cells. These results suggest that high CST1 expression may be involved in autophagic induction and protects from AF-induced cell death by inhibition of ROS generation through the regulation of GR activity.

Sepsis is a life-threatening condition that is caused by an abnormal immune response to infection and can lead to tissue damage, organ failure, and death. Erastin is a small molecule capable of initiating ferroptotic cell death in cancer cells. However, the function of erastin in the inflammatory response during sepsis remains unknown. Here, we showed that erastin ameliorates septic shock induced by cecal ligation and puncture or lipopolysaccharides (LPS) in mice, which was associated with a reduced production of inflammatory mediators such as nitric oxide, tumor necrosis factor (TNF)-α, and interleukin (IL)-1β. Pretreatment with erastin in bone marrow-derived macrophages (BMDMs) significantly attenuated the expression of inducible nitric oxide synthase, cyclooxygenase-2, TNF-α, and IL-1β mRNA in response to LPS treatment. Furthermore, we also showed that erastin suppresses phosphorylation of IκB kinase β, phosphorylation and degradation of IκBα, and nuclear translocation of nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) in LPS-stimulated BMDMs. Our findings suggest that erastin attenuates the inflammatory response by suppressing the NF-κB signaling pathway, resulting in inhibition of sepsis development. This study provides new insights regarding the potential therapeutic properties of erastin in sepsis.

We reported previously that tescalcin (TESC) levels were higher in tissue and serum from colorectal cancer (CRC) patients and suggested that TESC was a potential oncotarget in CRC. The aim of this study was to investigate the function of TESC in CRC invasion and metastatic potential. TESC expression was knocked down in CRC cells using small interfering RNA (siRNA). The expression of TESC siRNA reduced cell migration and invasion by inhibiting matrix metalloprotease (MMP) and the epithelial-mesenchymal transition (EMT) pathway. RT-PCR and Western blot analysis showed that TESC siRNA induced E-cadherin. Consistently, TESC overexpression in HCT116 (HCT/TESC) cells enhanced cell migration and invasion by activating MMP and the EMT pathway and reducing E-cadherin. The formation of liver metastatic nodules in vivo was strongly increased in mice injected with HCT/TESC cells compared with that in mice injected with HCT/mock cells. This study demonstrates that TESC is involved in cell migration, invasion, and EMT during CRC tumor invasion. These results implicate TESC as a metastatic mediator and provide a biological rationale for the adverse prognosis associated with elevated TESC expression in human CRC.

Damage to mitochondria induces mitophagy, a cellular process that is gaining interest for its therapeutic relevance to a variety of human diseases. However, the mechanism underlying mitochondrial depolarization and clearance in mitophagy remains poorly understood. We previously reported that mitochondria-induced cell death was caused by knockdown of Neisseria gonorrhoeae opacity-associated-interacting protein 5 in gastric cancer. In this study, we show that Neisseria gonorrhoeae opacity-associated-interacting protein 5 loss and gain of function modulates mitophagy induced by treatment with docetaxel, a chemotherapy drug for gastric cancer. The activation of mitophagy by Neisseria gonorrhoeae opacity-associated-interacting protein 5 overexpression promoted cell survival, preventing docetaxel-induced mitochondrial clearance. Conversely, short interfering RNA-mediated knockdown of Neisseria gonorrhoeae opacity-associated-interacting protein 5 accelerated docetaxel-induced apoptosis while increasing mitochondrial depolarization, reactive oxygen species, and endoplasmic reticulum stress and decreasing adenosine triphosphate production. We also found that the mitochondrial outer membrane proteins mitofusin 2 and phosphatase and tensin homolog-induced putative kinase 1 colocalized with Neisseria gonorrhoeae opacity-associated-interacting protein 5 in mitochondria and that mitofusin 2 knockdown altered Neisseria gonorrhoeae opacity-associated-interacting protein 5 expression. These findings indicate that Neisseria gonorrhoeae opacity-associated-interacting protein 5 modulates docetaxel-induced mitophagic cell death and therefore suggest that this protein comprises a potential therapeutic target for gastric cancer treatment.

DNA replication and sister chromatid cohesion 1 (DSCC1) combines with chromosome transmission-fidelity protein 18 (CTF18) to form a CTF18-DSCC1-CTF8 (CTF18-1-8) module, which in combination with CTF18-replication factor C (RFC) acts as a proliferating cell nuclear antigen (PCNA) loader during DNA replication-associated processes. It was found that DSCC1 was overexpressed in tumor tissues from patients with colon cancer and that the survival probability of patients with colon cancer was lower when the expression of cytosolic DSCC1 was higher in tumor regions (P=0.047). By using DSCC1-or CTF18-knockdown cell lines (HCT116-shDSCC1 or HCT116-shCTF18, respectively), it was confirmed that DSCC1-knockdown inhibits cell proliferation and invasion, but that CTF18-knockdown does not. Tumors in mice xenografted with shDSCC1 cells were significantly smaller compared with those in mice in the mock group or those xenografted with shCTF18 cells. The shDSCC1 cells were highly sensitive to γ-irradiation and other DNA replication inhibitory treatments, resulting in low cell viability. The present results suggested that DSCC1 is the most important component in the CTF18-1-8 module for CTF18-RFC and is highly relevant to the growth and metastasis of colon cancer cells, and, therefore, it may be a potential therapeutic target for colon cancer treatment.

Interleukin-21 is a common γ-chain cytokine that controls the immune responses of B cells, T cells, and natural killer cells. Targeting IL-21 to strengthen the immune system is promising for the development of vaccines as well as anti-infection and anti-tumor therapies. However, the practical application of IL-21 is limited by the high production cost. In this study, we improved IL-21 production by codon optimization and selection of appropriate signal peptide in CHO-K1 cells. Codon-optimized or non-optimized human IL-21 was stably transfected into CHO-K1 cells. IL-21 expression was 10-fold higher for codon-optimized than non-optimized IL-21. We fused five different signal peptides to codon-optimized mature IL-21 and evaluated their effect on IL-21 production. The best result (a 3-fold increase) was obtained using a signal peptide derived from human azurocidin. Furthermore, codon-optimized IL-21 containing the azurocidin signal peptide promoted IFN-γ secretion and STAT3 phosphorylation in NK-92 cells similar to codon-optimized IL-21 containing original signal peptide. Collectively, these results indicate that codon optimization and azurocidin signal peptides provide an efficient approach for the high-level production of IL-21 as a biopharmaceutical.

Correction to: Cell Death and Disease (2017) 8, e2682. doi:10.1038/cddis.2017.100; published online 16 March 2017 In the version of this article originally published, the following affiliation for Sang Chul Lee was incorrectly listed as 3 instead of 1. The correct affiliations are listed below: Byung Moo Oh1,2,5, Seon-Jin Lee1,2,5, Hee Jun Cho1, Yun Sun Park1, Jong-Tae Kim1, Suk Ran Yoon1, Sang Chul Lee1, Jong-Seok Lim3, Bo-Yeon Kim4, Yong-Kyung Choe1 and Hee Gu Lee1,2