Cisplatin Induces Kidney Cell Death via ROS-dependent MAPK Signaling Pathways by Targeting Peroxiredoxin I and II in African Green Monkey (Chlorocebus aethiops sabaeus) Kidney Cells.

BACKGROUND/AIM: Cisplatin [cis-diamminedichloroplatinum(II), CDDP] is a widely used and effective antitumor drug in clinical settings, notorious for its nephrotoxic side effects. This study investigated the mechanisms of CDDP-induced damage in African green monkey kidney (Vero) cells, with a focus on the role of Peroxiredoxin I (Prx I) and Peroxiredoxin II (Prx II) of the peroxiredoxin (Prx) family, which scavenge reactive oxygen species (ROS). MATERIALS AND METHODS: We utilized the Vero cell line derived from African green monkey kidneys and exposed these cells to various concentrations of CDDP. Cell viability, apoptosis, ROS levels, and mitochondrial membrane potential were assessed. RESULTS: CDDP significantly compromised Vero cell viability by elevating both cellular and mitochondrial ROS, which led to increased apoptosis. Pretreatment with the ROS scavenger N-acetyl-L-cysteine (NAC) effectively reduced CDDP-induced ROS accumulation and subsequent cell apoptosis. Furthermore, CDDP reduced Prx I and Prx II levels in a dose- and time-dependent manner. The inhibition of Prx I and II exacerbated cell death, implicating their role in CDDP-induced accumulation of cellular ROS. Additionally, CDDP enhanced the phosphorylation of MAPKs (p38, ERK, and JNK) without affecting AKT. The inhibition of these pathways significantly attenuated CDDP-induced apoptosis. CONCLUSION: The study highlights the involvement of Prx proteins in CDDP-induced nephrotoxicity and emphasizes the central role of ROS in cell death mediation. These insights offer promising avenues for developing clinical interventions to mitigate the nephrotoxic effects of CDDP.

PLK1 phosphorylates RhoGDI1 and promotes cancer cell migration and invasion.

BACKGROUND: Rho guanine nucleotide dissociation inhibitor 1 (RhoGDI1) plays an important role in diverse cellular processes by regulating Rho guanosine triphosphate (GTP)ases activity. RhoGDI1 phosphorylation regulates the spatiotemporal activation of Rho GTPases during cell migration. In this study, we identified polo-like kinase 1 (PLK1) as a novel kinase of RhoGDI1 and investigated the molecular mechanism by which the interaction between RhoGDI1 and PLK1 regulates cancer cell migration. METHODS: Immunoprecipitation, GST pull-down assay, and proximity ligation assay (PLA) were performed to analyze the interaction between RhoGDI1 and PLK1. In vitro kinase assay and immunoprecipitation were performed with Phospho-(Ser/Thr) antibody. We evaluated RhoA activation using RhoGTPases activity assay. Cell migration and invasion were analyzed by transwell assays. RESULTS: GST pull-down assays and PLA showed that PLK1 directly interacted with RhoGDI1 in vitro and in vivo. Truncation mutagenesis revealed that aa 90-111 of RhoGDI1 are critical for interacting with PLK1. We also showed that PLK1 phosphorylated RhoGDI1 at Thr7 and Thr91, which induces cell motility. Overexpression of the GFP-tagged RhoGDI1 truncated mutant (aa 90-111) inhibited the interaction of PLK1 with RhoGDI1 and attenuated RhoA activation by PLK1. Furthermore, the overexpression of the RhoGDI1 truncated mutant reduced cancer cell migration and invasion in vitro and suppressed lung metastasis in vivo. CONCLUSIONS: Collectively, we demonstrate that the phosphorylation of RhoGDI1 by PLK1 promotes cancer cell migration and invasion through RhoA activation. This study connects the interaction between PLK1 and RhoGDI1 to the promotion of cancer cell behavior associated with malignant progression, thereby providing opportunities for cancer therapeutic interventions.

Peroxiredoxin II regulates exosome secretion from dermal mesenchymal stem cells through the ISGylation signaling pathway.

BACKGROUND: Exosomes are small extracellular vesicles that play important roles in intercellular communication and have potential therapeutic applications in regenerative medicine. Dermal mesenchymal stem cells (DMSCs) are a promising source of exosomes due to their regenerative and immunomodulatory properties. However, the molecular mechanisms regulating exosome secretion from DMSCs are not fully understood. RESULTS: In this study, the role of peroxiredoxin II (Prx II) in regulating exosome secretion from DMSCs and the underlying molecular mechanisms were investigated. It was discovered that depletion of Prx II led to a significant reduction in exosome secretion from DMSCs and an increase in the number of intracellular multivesicular bodies (MVBs), which serve as precursors of exosomes. Mechanistically, Prx II regulates the ISGylation switch that controls MVB degradation and impairs exosome secretion. Specifically, Prx II depletion decreased JNK activity, reduced the expression of the transcription inhibitor Foxo1, and promoted miR-221 expression. Increased miR-221 expression inhibited the STAT signaling pathway, thus downregulating the expression of ISGylation-related genes involved in MVB degradation. Together, these results identify Prx II as a critical regulator of exosome secretion from DMSCs through the ISGylation signaling pathway. CONCLUSIONS: Our findings provide important insights into the molecular mechanisms regulating exosome secretion from DMSCs and highlight the critical role of Prx II in controlling the ISGylation switch that regulates DMSC-exosome secretion. This study has significant implications for developing new therapeutic strategies in regenerative medicine. Video Abstract.

IL-17A and Th17 Cells Contribute to Endometrial Cell Survival by Inhibiting Apoptosis and NK Cell Mediated Cytotoxicity of Endometrial Cells via ERK1/2 Pathway.

Immune status including the immune cells and cytokine profiles has been implicated in the development of endometriosis. In this study, we analyzed Th17 cells and IL-17A in peritoneal fluid (PF) and endometrial tissues of patients with (n=10) and without (n=26) endometriosis. Our study has shown increased Th17 cell population and IL-17A level in PF with endometriosis patients. To determine the roles of IL-17A and Th17 cells in the development of endometriosis, the effect of IL-17A, major cytokine of Th17, on endometrial cells isolated from endometriotic tissues was examined. Recombinant IL-17A promoted survival of endometrial cells accompanied by increased expression of anti-apoptotic genes, including Bcl-2 and MCL1, and the activation of ERK1/2 signaling. In addition, treatment of IL-17A to endometrial cells inhibited NK cell mediated cytotoxicity and induced HLA-G expression on endometrial cells. IL-17A also promoted migration of endometrial cells. Our data suggest that Th17 cells and IL-17A play critical roles in the development of endometriosis by promoting endometrial cell survival and conferring a resistance to NK cell cytotoxicity through the activation of ERK1/2 signaling. Targeting IL-17A has potential as a new strategy for the treatment of endometriosis.

Astragalus Complanatus Ethanol Attenuates Septic Shock by Exerting Anti-Inflammatory Effects on Macrophages.

Sepsis is a systemic inflammatory syndrome that results in multiple-organ failure caused by a dysregulated host immune response to microbial infection. Astragali complanati semen extract (ACSE) exhibits pharmacological activities, including antioxidant, anticancer, antiaging, and anti-diabetes effects. It is widely used in traditional medicine to treat liver and kidney diseases; however, the protective effect of ACSE on sepsis and its mechanisms are unknown. In the present study, we investigated the anti-inflammatory effects and potential mechanisms of the action of ACSE on sepsis. We show that ACSE improved survival rates in mouse models of acute sepsis induced by CLP (cecal ligation and puncture) and LPS stimulation. ACSE administration decreased aspartate aminotransferase (AST) and alanine aminotransferase (ALT) in sepsis-induced mice. Furthermore, ACSE reduced the levels of nitric oxide (NO), tumor necrosis factor-α (TNF-α), interleukin-1ß (IL-1ß), and interleukin-6 (IL-6) in the serum of septic mice. ACSE treatment inhibited the expression of these proinflammatory genes in LPS-stimulated J774 macrophages. Moreover, ACSE inhibited the phosphorylation of the IκB kinase (IKK) and the nuclear translocation of p65 NF-κB by LPS stimulation in macrophages. These results reveal the mechanism underlying the protective effect of ACSE against sepsis by inhibiting NF-κB activation and suggest that ACSE could be a potential therapeutic candidate to treat acute inflammatory diseases.

KLK6/PAR1 Axis Promotes Tumor Growth and Metastasis by Regulating Cross-Talk between Tumor Cells and Macrophages.

Kallikrein-related peptidase (KLK)6 is associated with inflammatory diseases and neoplastic progression. KLK6 is aberrantly expressed in several solid tumors and regulates cancer development, metastatic progression, and drug resistance. However, the function of KLK6 in the tumor microenvironment remains unclear. This study aimed to determine the role of KLK6 in the tumor microenvironment. Here, we uncovered the mechanism underlying KLK6-mediated cross-talk between cancer cells and macrophages. Compared with wild-type mice, KLK6-/- mice showed less tumor growth and metastasis in the B16F10 melanoma and Lewis lung carcinoma (LLC) xenograft model. Mechanistically, KLK6 promoted the secretion of tumor necrosis factor-alpha (TNF-α) from macrophages via the activation of protease-activated receptor-1 (PAR1) in an autocrine manner. TNF-α secreted from macrophages induced the release of the C-X-C motif chemokine ligand 1 (CXCL1) from melanoma and lung carcinoma cells in a paracrine manner. The introduction of recombinant KLK6 protein in KLK6-/- mice rescued the production of TNF-α and CXCL1, tumor growth, and metastasis. Inhibition of PAR1 activity suppressed these malignant phenotypes rescued by rKLK6 in vitro and in vivo. Our findings suggest that KLK6 functions as an important molecular link between macrophages and cancer cells during malignant progression, thereby providing opportunities for therapeutic intervention.

Ponciri Fructus Immaturus ethanol extract attenuates septic shock through inhibition of the STAT1 signaling pathway.

Sepsis is a systemic inflammatory disease to infections and results in tissue damage and multiple organ failure. Ponciri Fructus Immaturus (PFI) is widely used in traditional medicine for allergic inflammation and gastrointestinal disorders. However, the effect of PFI on sepsis is still unknown. This study investigated the anti-inflammatory and antiseptic effects of PFI ethanol extract (PFIE) in LPS-stimulated J774 macrophages and mice with CLP- or LPS-induced sepsis, respectively. PFIE attenuates the LPS-induced production of the proinflammatory mediator NO by inhibiting the expression of iNOS in J774 cells. Real-time RT-PCR data and ELISA showed that the mRNA and protein levels of TNF-α, IL-1ß, and IL-6 increased in LPS-stimulated J774 cells. However, this induction was significantly suppressed in PFIE pre-treated J774 cells. We also found that PFIE administration increased the survival rate of mice with LPS- and CLP-induced sepsis. Decreased serum levels of AST, ALT, and CK were observed after administration of PFIE, which was associated with reduced production of proinflammatory factors, such as NO, TNF-α, IL-1ß, and IL-6. Moreover, PFIE suppressed the phosphorylation and nuclear translocation of STAT1 in LPS-stimulated J774 cells, suggesting that PFIE can inhibit LPS- and CLP-induced septic shock by suppressing the STAT1 activation. These findings provide the potential therapeutic relevance of PFIE in treating acute inflammatory disease.

miR-302 Suppresses the Proliferation, Migration, and Invasion of Breast Cancer Cells by Downregulating ATAD2.

Breast cancer is the most common malignant tumor in women. The ATPase family AAA domain-containing protein 2 (ATAD2) contains an ATPase domain and a bromodomain, and is abnormally expressed in various human cancers, including breast cancer. However, the molecular mechanisms underlying the regulation of ATAD2 expression in breast cancer remain unclear. This study aimed to investigate the expression and function of ATAD2 in breast cancer. We found that ATAD2 was highly expressed in human breast cancer tissues and cell lines. ATAD2 depletion via RNA interference inhibited the proliferation, migration, and invasive ability of the SKBR3 and T47D breast cancer cell lines. Furthermore, Western blot analysis and luciferase assay results revealed that ATAD2 is a putative target of miR-302. Transfection with miR-302 mimics markedly reduced cell migration and invasion. These inhibitory effects of miR-302 were restored by ATAD2 overexpression. Moreover, miR-302 overexpression in SKBR3 and T47D cells suppressed tumor growth in the xenograft mouse model. However, ATAD2 overexpression rescued the decreased tumor growth seen after miR-302 overexpression. Our findings indicate that miR-302 plays a prominent role in inhibiting the cancer cell behavior associated with tumor progression by targeting ATAD2, and could thus be a valuable target for breast cancer therapy.

Collapsin response mediator protein 4 enhances the radiosensitivity of colon cancer cells through calcium­mediated cell signaling.

Radiation therapy is an effective treatment against various types of cancer, but some radiation­resistant cancer cells remain a major therapeutic obstacle; thus, understanding radiation resistance mechanisms is essential for cancer treatment. In this study, we established radiation­resistant colon cancer cell lines and examined the radiation­induced genetic changes associated with radiation resistance. Using RNA­sequencing analysis, collapsin response mediator protein 4 (CRMP4) was identified as the candidate gene associated with radiation sensitivity. When cells were exposed to radiation, intracellular Ca2+ influx, collapse of mitochondrial membrane potential, and cytochrome c release into the cytosol were increased, followed by apoptosis induction. Radiation treatment­ or Ca2+ ionophore A23187­induced apoptosis was significantly inhibited in CRMP4­deficient cells, including radiation­resistant or CRMP4­shRNA cell lines. Furthermore, treatment of CRMP4­deficient cells with low levels (<5 µM) of BAPTA­AM, a Ca2+ chelator, resulted in radiation resistance. Conversely, Ca2+ deficiency induced by a high BAPTA­AM concentration (>10 µM) resulted in higher cell death in the CRMP4­depleted cells compared to CRMP4­expressing control cells. Our results suggest that CRMP4 plays an important role in Ca2+­mediated cell death pathways under radiation exposure and that CRMP4 may be a therapeutical target for colon cancer treatment.

TXNIP Regulates Natural Killer Cell-Mediated Innate Immunity by Inhibiting IFN-γ Production during Bacterial Infection.

The function of natural killer (NK) cell-derived interferon-γ (IFN-γ) expands to remove pathogens by increasing the ability of innate immune cells. Here, we identified the critical role of thioredoxin-interacting protein (TXNIP) in the production of IFN-γ in NK cells during bacterial infection. TXNIP inhibited the production of IFN-γ and the activation of transforming growth factor ß-activated kinase 1 (TAK1) activity in primary mouse and human NK cells. TXNIP directly interacted with TAK1 and inhibited TAK1 activity by interfering with the complex formation between TAK1 and TAK1 binding protein 1 (TAB1). Txnip-/- (KO) NK cells enhanced the activation of macrophages by inducing IFN-γ production during Pam3CSK4 stimulation or Staphylococcus aureus (S. aureus) infection and contributed to expedite the bacterial clearance. Our findings suggest that NK cell-derived IFN-γ is critical for host defense and that TXNIP plays an important role as an inhibitor of NK cell-mediated macrophage activation by inhibiting the production of IFN-γ during bacterial infection.

Cullin 3/KCTD5 Promotes the Ubiqutination of Rho Guanine Nucleotide Dissociation Inhibitor 1 and Regulates Its Stability.

Rho guanine nucleotide dissociation inhibitor 1 (RhoGDI1) plays important roles in numerous cellular processes, including cell motility, adhesion, and proliferation, by regulating the activity of Rho GTPases. Its expression is altered in various human cancers and is associated with malignant progression. Here, we show that RhoGDI1 interacts with Cullin 3 (CUL3), a scaffold protein for E3 ubiquitin ligase complexes. Ectopic expression of CUL3 increases the ubiquitination of RhoGDI1. Furthermore, potassium channel tetramerization domain containing 5 (KCTD5) also binds to RhoGDI1 and increases its interaction with CUL3. Ectopic expression of KCTD5 increases the ubiquitination of RhoGDI1, whereas its knockdown by RNA interference has the opposite effect. Depletion of KCTD5 or expression of dominant-negative CUL3 (DN-CUL3) enhances the stability of RhoGDI1. Our findings reveal a previously unknown mechanism for controlling RhoGDI1 degradation that involves a CUL3/KCTD5 ubiquitin ligase complex.

Regulation of Hematopoietic Stem Cell Fate and Malignancy.

The regulation of hematopoietic stem cell (HSC) fate decision, whether they keep quiescence, self-renew, or differentiate into blood lineage cells, is critical for maintaining the immune system throughout one's lifetime. As HSCs are exposed to age-related stress, they gradually lose their self-renewal and regenerative capacity. Recently, many reports have implicated signaling pathways in the regulation of HSC fate determination and malignancies under aging stress or pathophysiological conditions. In this review, we focus on the current understanding of signaling pathways that regulate HSC fate including quiescence, self-renewal, and differentiation during aging, and additionally introduce pharmacological approaches to rescue defects of HSC fate determination or hematopoietic malignancies by kinase signaling pathways.

Dysregulation of Rho GTPases in Human Cancers.

Rho GTPases play central roles in numerous cellular processes, including cell motility, cell polarity, and cell cycle progression, by regulating actin cytoskeletal dynamics and cell adhesion. Dysregulation of Rho GTPase signaling is observed in a broad range of human cancers, and is associated with cancer development and malignant phenotypes, including metastasis and chemoresistance. Rho GTPase activity is precisely controlled by guanine nucleotide exchange factors, GTPase-activating proteins, and guanine nucleotide dissociation inhibitors. Recent evidence demonstrates that it is also regulated by post-translational modifications, such as phosphorylation, ubiquitination, and sumoylation. Here, we review the current knowledge on the role of Rho GTPases, and the precise mechanisms controlling their activity in the regulation of cancer progression. In addition, we discuss targeting strategies for the development of new drugs to improve cancer therapy.

Erastin Inhibits Septic Shock and Inflammatory Gene Expression via Suppression of the NF-κB Pathway.

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)-1ß. Pretreatment with erastin in bone marrow-derived macrophages (BMDMs) significantly attenuated the expression of inducible nitric oxide synthase, cyclooxygenase-2, TNF-α, and IL-1ß mRNA in response to LPS treatment. Furthermore, we also showed that erastin suppresses phosphorylation of IκB kinase ß, 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.

DNA Replication and Sister Chromatid Cohesion 1 (DSCC1) of the Replication Factor Complex CTF18-RFC is Critical for Colon Cancer Cell Growth.

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.

Regulation of Rho GTPases by RhoGDIs in Human Cancers.

Rho GDP dissociation inhibitors (RhoGDIs) play important roles in various cellular processes, including cell migration, adhesion, and proliferation, by regulating the functions of the Rho GTPase family. Dissociation of Rho GTPases from RhoGDIs is necessary for their spatiotemporal activation and is dynamically regulated by several mechanisms, such as phosphorylation, sumoylation, and protein interaction. The expression of RhoGDIs has changed in many human cancers and become associated with the malignant phenotype, including migration, invasion, metastasis, and resistance to anticancer agents. Here, we review how RhoGDIs control the function of Rho GTPases by regulating their spatiotemporal activity and describe the regulatory mechanisms of the dissociation of Rho GTPases from RhoGDIs. We also discuss the role of RhoGDIs in cancer progression and their potential uses for therapeutic intervention.

Morin Hydrate Reverses Cisplatin Resistance by Impairing PARP1/HMGB1-Dependent Autophagy in Hepatocellular Carcinoma.

Chemoresistance is a major obstacle that limits the benefits of cisplatin-based chemotherapy in various cancers, including hepatocellular carcinoma. De-regulation of the poly(ADP-ribose) polymerase 1 (PARP1)/high-mobility group box 1 (HMGB1) signaling pathway has been proposed as an important mechanism involved in cisplatin-resistance. In this study, we investigated therapeutic potential of a natural flavonoid Morin hydrate against cisplatin-induced toxicity using the HepG2DR multi-drug resistant cell line, which is derived from the HepG2 human hepatocellular carcinoma cell line. HepG2DR cells were exposed to cisplatin and Morin hydrate alone or together after which autophagy and apoptotic signaling pathways were monitored by fluorometric assay and Western blot analysis. Xenograft mouse models were performed to confirm the in vitro effect of Morin hydrate. PARP1 was hyper activated in cisplatin-resistant HepG2DR cells. Cisplatin-induced PARP1 activation resulted in chemoresistance via increased autophagy. The cisplatin/Morin hydrate combination was effective in the reversal of the HepG2DR cell resistance via suppression of PARP1-mediated autophagy by regulating the HMGB1 and microtubule-associated protein 1A/1B light chain 3B (LC3) I/II. Moreover, PARP1 inhibition by 4-amino-1,8-naphthalimide or autophagy inhibition by a knockdown of the autophagy-related 5 (Atg5) gene resulted in sensitizing the HepG2DR cells to cisplatin (CP) through activation of the c-Jun N-terminal kinase (JNK) pathway. In a mouse xenograft model, the treatment of cisplatin with Morin hydrate reversed the increased expression of PARP and HMGB1 and significantly suppressed tumor growth. These findings indicate dysregulated expression of PARP1 confers cisplatin-resistance via autophagy activation in HepG2DR cells. Morin hydrate inhibits cisplatin-mediated autophagy induction, resulting in increased susceptibility of HepG2DR cells to cisplatin cytotoxicity. The combination of Morin hydrate with cisplatin may be a promising therapeutic strategy to enhance the efficacy of conventional chemotherapeutic drugs.

p38 Stabilizes Snail by Suppressing DYRK2-Mediated Phosphorylation That Is Required for GSK3ß-ßTrCP-Induced Snail Degradation.

Snail is a key regulator of epithelial-mesenchymal transition (EMT), which is a major step in tumor metastasis. Although the induction of Snail transcription precedes EMT, posttranslational regulation, especially phosphorylation of Snail, is critical for determining Snail protein levels or stability, subcellular localization, and the ability to induce EMT. To date, several kinases are known that enhance the stability of Snail by preventing its ubiquitination; however, the molecular mechanism(s) underlying this are still unclear. Here, we identified p38 MAPK as a crucial posttranslational regulator that enhances the stability of Snail. p38 directly phosphorylated Snail at Ser107, and this effectively suppressed DYRK2-mediated Ser104 phosphorylation, which is critical for GSK3ß-dependent Snail phosphorylation and ßTrCP-mediated Snail ubiquitination and degradation. Importantly, functional studies and analysis of clinical samples established a crucial role for the p38-Snail axis in regulating ovarian cancer EMT and metastasis. These results indicate the potential therapeutic value of targeting the p38-Snail axis in ovarian cancer. SIGNIFICANCE: These findings identify p38 MAPK as a novel regulator of Snail protein stability and potential therapeutic target in ovarian cancer.

G protein-coupled estrogen receptor-1 agonist induces chemotherapeutic effect via ER stress signaling in gastric cancer.

G protein-coupled estrogen receptor (GPER) is known to play an important role in hormone-associated cancers. G-1, a novel synthetic GPER agonist, has been reported to exhibit anti-carcinogenic properties. However, the chemotherapeutic mechanism of GPER is yet unclear. Here, we evaluated GPER expression in human gastric cancer tissues and cells. We found that G-1 treatment attenuates GPER expression in gastric cancer. GPER expression increased G-1-induced antitumor effects in mouse xenograft model. We analyzed the effects of knockdown/overexpression of GPER on G-1-induced cell death in cancer cells. Increased GPER expression in human gastric cancer cells increased G-1-induced cell death via increased levels of cleaved caspase-3, -9, and cleaved poly ADP-ribose polymerase. Interestingly, during G-1-induced cell death, GPER mRNA and protein expression was attenuated and associated with ER stress-induced expression of PERK, ATF-4, GRP-78, and CHOP. Furthermore, PERK-dependent induction of ER stress activation increased G-1-induced cell death, whereas PERK silencing decreased cell death and increased drug sensitivity. Taken together, the data suggest that the induction of ER stress via GPER expression may increase G-1-induced cell death in gastric cancer cells. These results may contribute to a new paradigm shift in gastric cancer therapy. [BMB Reports 2019; 52(11): 647-652].

Epsilon-Globin HBE1 Enhances Radiotherapy Resistance by Down-Regulating BCL11A in Colorectal Cancer Cells.

Resistance to radiotherapy is considered an important obstacle in the treatment of colorectal cancer. However, the mechanisms that enable tumor cells to tolerate the effects of radiation remain unclear. Moreover, radiotherapy causes accumulated mutations in transcription factors, which can lead to changes in gene expression and radiosensitivity. This phenomenon reduces the effectiveness of radiation therapy towards cancer cells. In the present study, radiation-resistant (RR) cancer cells were established by sequential radiation exposure, and hemoglobin subunit epsilon 1 (HBE1) was identified as a candidate radiation resistance-associated protein based on RNA-sequencing analysis. Then, compared to radiosensitive (RS) cell lines, the overexpression of HBE1 in RR cell lines was used to measure various forms of radiation-induced cellular damage. Consequently, HBE1-overexpressing cell lines were found to exhibit decreased radiation-induced intracellular reactive oxygen species (ROS) production and cell mortality. Conversely, HBE1 deficiency in RR cell lines increased intracellular ROS production, G2/M arrest, and apoptosis, and decreased clonogenic survival rate. These effects were reversed by the ROS scavenger N-acetyl cysteine. Moreover, HBE1 overexpression was found to attenuate radiation-induced endoplasmic reticulum stress and apoptosis via an inositol-requiring enzyme 1(IRE1)-Jun amino-terminal kinase (JNK) signaling pathway. In addition, increased HBE1 expression induced by γ-irradiation in RS cells attenuated expression of the transcriptional regulator BCL11A, whereas its depletion in RR cells increased BCL11A expression. Collectively, these observations indicate that the expression of HBE1 during radiotherapy might potentiate the survival of radiation-exposed colorectal cancer cells.