miR-216b regulation of c-Jun mediates GADD153/CHOP-dependent apoptosis

Desmoglein-2 Affects Vascular Function in Moyamoya Disease by Interacting with MMP-9 and Influencing PI3K Signaling

The pathogenesis and development of Moyamoya disease are still unclear. This study aimed to investigate the effect of desmoglein-2 (DSG2) on Moyamoya disease and determine the inhibitory effect of DSG2 in vascular remodeling in Moyamoya disease.RNA sequencing, immunohistochemistry (IHC), and western blotting were used to detect the expression of DSG2 in the superficial temporal artery (STA) tissues of Moyamoya disease. The association between DSG2 and endothelial cells' biological activities was investigated by cell counting kit-8 (CCK-8), migration assay, tube formation assay, flow cytometry with Annexin V-FITC/PI staining, and TUNEL apoptotic cell detection kit. Pathways affected by overexpression or knockdown of DSG2 were identified in endothelial cells.The expression of DSG2 in the STA tissues of Moyamoya disease was lower than that in normal controls. Overexpression of DSG2 inhibits the proliferation and migration but promotes apoptosis in endothelial cells, and low DSG2 levels result in impaired angiogenesis. In addition, there was an interaction between DSG2 and MMP-9, and DSG2 acted through the PI3K signaling in endothelial cells.Our results indicate that DSG2 affects PI3K signaling in vascular endothelial cells, and MMP-9 is involved in DSG2-mediated vascular changes in Moyamoya disease.

Multi-omics reveals bufadienolide Q-markers of Bufonis Venenum based on antitumor activity and cardiovascular toxicity in zebrafish

BACKGROUND

Bufonis Venenum (BV) is a traditional animal-based Chinese medicine with therapeutic effects against cancer. However, its clinical use is significantly restricted due to associated cardiovascular risks. BV's value in China's market is typically assessed based on "content priority," focusing on indicator components. However, these components of BV possess both antitumor activity and toxicity, and the correlation between the antitumor activity and toxicity of BV has not yet been elucidated.

PURPOSE

This study employs an integrated multi-omics approach to identify bufadienolide Q-markers and explore the correlation between BV's antitumor activity and toxicity. The aim is to establish a more comprehensive method for BV's quality.

METHODS

Normal zebrafish and HepG2 xenograft zebrafish were chosen as activity and toxicity evaluation models. Ultra-high performance liquid chromatography (UHPLC) coupled with a linear ion trap orbitrap (LTQ-Orbitrap) mass spectrometry was used to quantify eight batches of BV and key "toxic and effective" components were screened out. Transcriptomic and metabolomic analyses were performed to elucidate the regulatory mechanisms underlying the antitumor activity and cardiovascular toxicity of the key components in BV.

RESULTS

Eight key "toxic and effective" compounds were identified: resibufogenin, cinobufagin, arenobufagin, bufotalin, bufalin, gamabufotalin, desacetylcinobufagin, and telocinobufagin. The findings showed that bufalin and cinobufagin interfered with calcium homeostasis through CaV and CaSR, induced cardiotoxicity, and upregulated CASP9 to activate myocardial cell apoptosis. However, desacetylcinobufagin exhibited greater potential in terms of anti-tumor effects. Combining the results of untargeted and targeted metabolomics revealed that desacetylcinobufagin could have a callback effect on differential lipids and correct abnormal energy and amino acid metabolism caused by cancer, similar to cinobufagin and bufalin. Microscale thermophoresis (MST) ligand binding measurements also showed that the binding of desacetylcinobufagin to GPX4 has a more potent ability to induce ferroptosis in tumor cells compared to cinobufagin.

CONCLUSION

An innovative evaluation method based on the zebrafish was developed to investigate the relationship between the toxicity and efficacy of BV. This study identified toxicity and activity Q-markers and explored the mechanism between the two effects of BV. The research data could offer valuable insights into the efficacy of BV. Additionally, desacetylcinobufagin, an active ingredient with low toxicity, was found to enhance the quality of BV.

Oncoprotein LAMTOR5-mediated CHOP silence via DNA hypermethylation and miR-182/miR-769 in promotion of liver cancer growth

C/EBP homologous protein (CHOP) triggers the death of multiple cancers via endoplasmic reticulum (ER) stress. However, the function and regulatory mechanism of CHOP in liver cancer remain elusive. We have reported that late endosomal/lysosomal adapter, mitogen-activated protein kinase and mTOR activator 5 (LAMTOR5) suppresses apoptosis in various cancers. Here, we show that the transcriptional and posttranscriptional inactivation of CHOP mediated by LAMTOR5 accelerates liver cancer growth. Clinical bioinformatic analysis revealed that the expression of CHOP was low in liver cancer tissues and that its increased expression predicted a good prognosis. Elevated CHOP contributed to destruction of LAMTOR5-induced apoptotic suppression and proliferation. Mechanistically, LAMTOR5-recruited DNA methyltransferase 1 (DNMT1) to the CpG3 region (-559/-429) of the CHOP promoter and potentiated its hypermethylation to block its interaction with general transcription factor IIi (TFII-I), resulting in its inactivation. Moreover, LAMTOR5-enhanced miR-182/miR-769 reduced CHOP expression by targeting its 3'UTR. Notably, lenvatinib, a first-line targeted therapy for liver cancer, could target the LAMTOR5/CHOP axis to prevent liver cancer progression. Accordingly, LAMTOR5-mediated silencing of CHOP via the regulation of ER stress-related apoptosis promotes liver cancer growth, providing a theoretical basis for the use of lenvatinib for the treatment of liver cancer.

METTL16 deficiency attenuates apoptosis through translational control of extrinsic death receptor during nutrient deprivation

METTL16 is a well-characterized m6A methyltransferase that has been reported to contribute to tumorigenesis in various types of cancer. However, the effect of METTL16 on tumor progression under restricted nutrient conditions, which commonly occur in tumor microenvironment, has yet to be elucidated. Herein, our study initially reported the inhibitory effect of METTL16 depletion on apoptosis under amino acid starvation conditions. Mechanistically, we determined that the METTL16 knockdown represses the expression of extrinsic death receptors at both transcription and translation levels. Depletion of METTL16 prevented protein synthesis of GCN2, resulting in diminished ATF4 expression in a GCN2-eIF2α-dependent manner. Reduction of ATF4 further declined the expression of apoptotic receptor protein DR5. Meanwhile, METTL16 deficiency directly hampered protein synthesis of FADD and DR5, thereby impairing apoptosis and promoting cancer cell survival. Taken together, our study provides novel evidence for the involvement of METTL16 in regulating cancer progression, suggesting that METTL16 as a potential therapeutic target for cancer treatment.

miR-217 Regulates Normal and Tumor Cell Fate Following Induction of Endoplasmic Reticulum Stress

Rapidly proliferating cancer cells require a microenvironment where essential metabolic nutrients like glucose, oxygen, and growth factors become scarce as the tumor volume surpasses the established vascular capacity of the tissue. Limits in nutrient availability typically trigger growth arrest and/or apoptosis to prevent cellular expansion. However, tumor cells frequently co-opt cellular survival pathways thereby favoring cell survival under this environmental stress. The unfolded protein response (UPR) pathway is typically engaged by tumor cells to favor adaptation to stress. PERK, an endoplasmic reticulum (ER) protein kinase and UPR effector is activated in tumor cells and contributes tumor cell adaptation by limiting protein translation and balancing redox stress. PERK also induces miRNAs that contribute to tumor adaptation. miR-211 and miR-216b were previously identified as PERK-ATF4-regulated miRNAs that regulate cell survival. We have identified another PERK-responsive miRNA, miR-217, with increased expression under prolonged ER stress. Key targets of miR-217 are identified as TRPM1, the host gene for miR-211 and EZH2. Evidence is provided that miR-217 expression is essential for the rapid loss of miR-211 in prolonged ER stress and provides a functional link for determining whether cells adapt to stress or commit to apoptosis.

IMPLICATIONS

PERK-dependent induction of miR-217 limits accumulation and function of the prosurvival miRNA, miR-211, to establish cell fate and promote cell commitment to apoptosis.

Transcriptional signatures in human macrophage-like cells infected by Leishmania infantum, Leishmania major and Leishmania tropica

BACKGROUND

In the Mediterranean basin, three Leishmania species have been identified: L. infantum, L. major and L. tropica, causing zoonotic visceral leishmaniasis (VL), zoonotic cutaneous leishmaniasis (CL) and anthroponotic CL, respectively. Despite animal models and genomic/transcriptomic studies provided important insights, the pathogenic determinants modulating the development of VL and CL are still poorly understood. This work aimed to identify host transcriptional signatures shared by cells infected with L. infantum, L. major, and L. tropica, as well as specific transcriptional signatures elicited by parasites causing VL (i.e., L. infantum) and parasites involved in CL (i.e., L. major, L. tropica).

METHODOLOGY/PRINCIPAL FINDINGS

U937 cells differentiated into macrophage-like cells were infected with L. infantum, L. major and L. tropica for 24h and 48h, and total RNA was extracted. RNA sequencing, performed on an Illumina NovaSeq 6000 platform, was used to evaluate the transcriptional signatures of infected cells with respect to non-infected cells at both time points. The EdgeR package was used to identify differentially expressed genes (fold change > 2 and FDR-adjusted p-values < 0.05). Then, functional enrichment analysis was employed to identify the enriched ontology terms in which these genes are involved. At 24h post-infection, a common signature of 463 dysregulated genes shared among all infection conditions was recognized, while at 48h post-infection the common signature was reduced to 120 genes. Aside from a common transcriptional response, we evidenced different upregulated functional pathways characterizing L. infantum-infected cells, such as VEGFA-VEGFR2 and NFE2L2-related pathways, indicating vascular remodeling and reduction of oxidative stress as potentially important factors for visceralization.

CONCLUSIONS

The identification of pathways elicited by parasites causing VL or CL could lead to new therapeutic strategies for leishmaniasis, combining the canonical anti-leishmania compounds with host-directed therapy.

A novel bystander effect in tamoxifen treatment: PPIB derived from ER+ cells attenuates ER- cells via endoplasmic reticulum stress-induced apoptosis

Tamoxifen (TAM) is the frontline therapy for estrogen receptor-positive (ER+) breast cancer in premenopausal women that interrupts ER signaling. As tumors with elevated heterogeneity, amounts of ER-negative (ER-) cells are present in ER+ breast cancer that cannot be directly killed by TAM. Despite complete remissions have been achieved in clinical practice, the mechanism underlying the elimination of ER- cells during TAM treatment remains an open issue. Herein, we deciphered the elimination of ER- cells in TAM treatment from the perspective of the bystander effect. Markable reductions were observed in tumorigenesis of ER- breast cancer cells by applying both supernatants from TAM-treated ER+ cells and a transwell co-culture system, validating the presence of a TAM-induced bystander effect. The major antitumor protein derived from ER+ cells, peptidyl-prolyl cis-trans isomerase B (PPIB), is the mediator of the TAM-induced bystander effect identified by quantitative proteomics. The attenuation of ER- cells was attributed to activated BiP/eIF2α/CHOP axis and promoted endoplasmic reticulum stress (ERS)-induced apoptosis, which can also be triggered by PPIB independently. Altogether, our study revealed a novel TAM-induced bystander effect in TAM treatment of ER+ breast cancer, raising the possibility of developing PPIB as a synergistic antitumor agent or even substitute endocrine therapy.

The role of milk fat globule size in modulating the composition of postbiotics produced by Bacillus subtilis and their effect on mammary epithelial cells

Milk lipids are secreted into the milk collecting ducts as milk fat globule (MFG) where they are exposed to microflora of the udder. We hypothesized that MFG size modulates the metabolic fingerprint of B. subtilis. Accordingly, small and large (2.3 and 7.0 µm, respectively) MFG were isolated from cow milk and used as a substrate for B. subtilis. Small MFG enhanced growth, whereas large MFG enhanced biofilm formation. Bacteria incubated with small MFG had increased concentration of metabolites related to energy production whereas metabolome of the bacteria incubated with large MFG had reduced concentrations of metabolites important for biofilm formation. Postbiotics from bacteria grown on large MFG exacerbated the proinflammatory response of MEC to LPS, and changed the expression of key enzymes involved in lipid and protein synthesis. Our results suggest that MFG size modulate growth trajectories and metabolome of B. subtilis, and consequently the stress response of host cells.

ER stress: an emerging regulator in GVHD development

Allogeneic hematopoietic cell transplantation (allo-HCT) is a promising therapeutic option for hematologic malignancies. However, the clinical benefits of allo-HCT are limited by the development of complications including graft-versus-host disease (GVHD). Conditioning regimens, such as chemotherapy and irradiation, which are administered to the patients prior to allo-HCT, can disrupt the endoplasmic reticulum (ER) homeostasis, and induce ER stress in the recipient's cells. The conditioning regimen activates antigen-presenting cells (APCs), which, in turn, activate donor cells, leading to ER stress in the transplanted cells. The unfolded protein response (UPR) is an evolutionarily conserved signaling pathway that manages ER stress in response to cellular stress. UPR has been identified as a significant regulatory player that influences the function of various immune cells, including T cells, B cells, macrophages, and dendritic cells (DCs), in various disease progressions. Therefore, targeting the UPR pathway has garnered significant attention as a promising approach for the treatment of numerous diseases, such as cancer, neurodegeneration, diabetes, and inflammatory diseases. In this review, we summarize the current literature regarding the contribution of ER stress response to the development of GVHD in both hematopoietic and non-hematopoietic cells. Additionally, we explore the potential therapeutic implications of targeting UPR to enhance the effectiveness of allo-HCT for patients with hematopoietic malignancies.

Induction of the activating transcription factor-4 in the intratumoral CD8+ T cells sustains their viability and anti-tumor activities

Immune suppressive factors of the tumor microenvironment (TME) undermine viability and exhaust the activities of the intratumoral cytotoxic CD8 + T lymphocytes (CTL) thereby evading anti-tumor immunity and decreasing the benefits of immune therapies. To counteract this suppression and improve the efficacy of therapeutic regimens, it is important to identify and understand the critical regulators within CD8 + T cells that respond to TME stress and tumor-derived factors. Here we investigated the regulation and importance of activating transcription factor-4 (ATF4) in CTL using a novel Atf4ΔCD8 mouse model lacking ATF4 specifically in CD8 + cells. Induction of ATF4 in CD8 + T cells occurred in response to antigenic stimulation and was further increased by exposure to tumor-derived factors and TME conditions. Under these conditions, ATF4 played a critical role in the maintenance of survival and activities of CD8 + T cells. Conversely, selective ablation of ATF4 in CD8 + T cells in mice rendered these Atf4ΔCD8 hosts prone to accelerated growth of implanted tumors. Intratumoral ATF4-deficient CD8 + T cells were under-represented compared to wild-type counterparts and exhibited impaired activation and increased apoptosis. These findings identify ATF4 as an important regulator of viability and activity of CD8 + T cells in the TME and argue for caution in using agents that could undermine these functions of ATF4 for anti-cancer therapies.

Dynasore Protects Corneal Epithelial Cells Subjected to Hyperosmolar Stress in an In Vitro Model of Dry Eye Epitheliopathy

Epitheliopathy at the ocular surface is a defining sign of dry eye disease, a common disorder that affects 10% to 30% of the world's population. Hyperosmolarity of the tear film is one of the main drivers of pathology, with subsequent endoplasmic reticulum (ER) stress, the resulting unfolded protein response (UPR), and caspase-3 activation implicated in the pathway to programmed cell death. Dynasore, is a small molecule inhibitor of dynamin GTPases that has shown therapeutic effects in a variety of disease models involving oxidative stress. Recently we showed that dynasore protects corneal epithelial cells exposed to the oxidant tBHP, by selective reduction in expression of CHOP, a marker of the UPR PERK branch. Here we investigated the capacity of dynasore to protect corneal epithelial cells subjected to hyperosmotic stress (HOS). Similar to dynasore's capacity to protect against tBHP exposure, dynasore inhibits the cell death pathway triggered by HOS, protecting against ER stress and maintaining a homeostatic level of UPR activity. However, unlike with tBHP exposure, UPR activation due to HOS is independent of PERK and mostly driven by the UPR IRE1 branch. Our results demonstrate the role of the UPR in HOS-driven damage, and the potential of dynasore as a treatment to prevent dry eye epitheliopathy.

Traditional Chinese medicine suppressed cancer progression by targeting endoplasmic reticulum stress responses: A review

Cancer has a high morbidity and mortality; therefore, it poses a major global health concern. Imbalance in endoplasmic reticulum homeostasis can induce endoplasmic reticulum stress (ERS). ERS has been shown to play both tumor-promoting and tumor-suppressive roles in various cancer types by activating a series of adaptive responses to promote tumor cell survival and inducing ERS-related apoptotic pathways to promote tumor cell death, inhibit tumor growth and suppress tumor invasion. Because multiple roles of ERS in tumors continue to be reported, many studies have attempted to target ERS in cancer therapy. The therapeutic effects of traditional Chinese medicine (TCM) treatments on tumors have been widely recognized. TCM treatments can enhance the sensitivity of tumor radiotherapy, delay tumor recurrence and improve patients' quality of life. However, there are relatively few reports exploring the antitumor effects of TCM from the perspective of ERS. This review addresses the progress of TCM intervention in tumors via ERS with a view to providing a new direction for tumor treatment.

Graphene Oxide Enhances Biogenesis and Release of Exosomes in Human Ovarian Cancer Cells

BACKGROUND

Exosomes, which are nanovesicles secreted by almost all the cells, mediate intercellular communication and are involved in various physiological and pathological processes. We aimed to investigate the effects of graphene oxide (GO) on the biogenesis and release of exosomes in human ovarian cancer (SKOV3) cells.

METHODS

Exosomes were isolated using ultracentrifugation and ExoQuick and characterized by various analytical techniques. The expression levels of exosome markers were analyzed via quantitative reverse transcription-polymerase chain reaction and enzyme-linked immunosorbent assay.

RESULTS

Graphene oxide (10-50 μg/mL), cisplatin (2-10 μg/mL), and C6-ceramide (5-25 μM) inhibited the cell viability, proliferation, and cytotoxicity in a dose-dependent manner. We observed that graphene oxide (GO), cisplatin (CIS), and C6-Ceramide (C6-Cer) stimulated acetylcholine esterase and neutral sphingomyelinase activity, total exosome protein concentration, and exosome counts associated with increased level of apoptosis, oxidative stress and endoplasmic reticulum stress. In contrast, GW4869 treatment inhibits biogenesis and release of exosomes. We observed that the human ovarian cancer cells secreted exosomes with typical cup-shaped morphology and surface protein biomarkers. The expression levels of TSG101, CD9, CD63, and CD81 were significantly higher in GO-treated cells than in control cells. Further, cytokine and chemokine levels were significantly higher in exosomes isolated from GO-treated SKOV3 cells than in those isolated from control cells. SKOV3 cells pre-treated with N-acetylcysteine or GW4869 displayed a significant reduction in GO-induced exosome biogenesis and release. Furthermore, endocytic inhibitors decrease exosome biogenesis and release by impairing endocytic pathways.

CONCLUSION

This study identifies GO as a potential tool for targeting the exosome pathway and stimulating exosome biogenesis and release. We believe that the knowledge acquired in this study can be potentially extended to other exosome-dominated pathologies and model systems. Furthermore, these nanoparticles can provide a promising means to enhance exosome production in SKOV3 cells.

Decoding endoplasmic reticulum stress signals in cancer cells and antitumor immunity

The tumor microenvironment (TME) provokes endoplasmic reticulum (ER) stress in malignant cells and infiltrating immune populations. Sensing and responding to ER stress is coordinated by the unfolded protein response (UPR), an integrated signaling pathway governed by three ER stress sensors: activating transcription factor (ATF6), inositol-requiring enzyme 1α (IRE1α), and protein kinase R (PKR)-like ER kinase (PERK). Persistent UPR activation modulates malignant progression, tumor growth, metastasis, and protective antitumor immunity. Hence, therapies targeting ER stress signaling can be harnessed to elicit direct tumor killing and concomitant anticancer immunity. We highlight recent findings on the role of the ER stress responses in onco-immunology, with an emphasis on genetic vulnerabilities that render tumors highly sensitive to therapeutic UPR modulation.

Long noncoding RNA LIPH-4 promotes esophageal squamous cell carcinoma progression by regulating the miR-216b/IGF2BP2 axis

Introduction

Esophageal squamous cell carcinoma (ESCC) represents a major malignancy with poor clinical outcomes. Long noncoding RNAs (lncRNAs) are known to regulate the development and progression of multiple cancers. However, how lncRNAs are involved in ESCC is currently undefined.

Methods

LIPH-4 levels in ESCC tissue specimens and cells were assessed by qRT-PCR. The biological function of LIPH-4 was examined in cell and animal studies, applying CCK-8, EdU, colony formation and flow cytometry assays as well as xenograft model experiments. The underlying mechanisms of action of LIPH-4 were explored through bioinformatics, luciferase reporter assay, RNA-immunoprecipitation assay and immunoblot.

Results

We identified a novel lncRNA, LIPH-4, which showed elevated amounts in ESCC tissues and positive correlations with increased tumor size and poor prognosis in ESCC patients. Functional studies showed that LIPH-4 promoted the growth, mediated cell cycle progression and inhibited apoptosis in ESCC cells in vitro, and promoted tumor growth in mice. In terms of mechanism, LIPH-4 could bind to miR-216b and act as a competing endogenous RNA (ceRNA) to induce the expression of miR-216’s target gene IGF2BP2. LIPH-4 played an oncogenic role in ESCC through the miR-216b/IGF2BP2 axis.

Conclusions

This study suggested that LIPH-4 functions as a novel oncogenic lncRNA by acting as a ceRNA for miR-216b to regulate IGF2BP2, indicating LIPH-4 likely constitutes a prognostic biomarker and therapeutic target in ESCC.

Supplementary Information

The online version contains supplementary material available at 10.1186/s40364-022-00408-x.

Melatonin regulates proliferation, apoptosis and invasion of trophoblasts in preeclampsia by inhibiting endoplasmic reticulum stress

AIMS

Clinical evidence indicated the activation of endoplasmic reticulum stress (ERS) in pregnant women with preeclampsia (PE), and the regulatory role of melatonin (MT) in ERS. This study aims to explore the possible effect and mechanism of MT on ERS and on the infiltration of trophoblasts in PE.

METHODS

The serum expression levels of MT and GRP78 in pregnant women with PE were measured. The cell proliferation, invasion, migration and apoptosis of trophoblasts were also determined. The trophoblast cell infiltration in placenta tissues was detected in EVOS image system. The expressions of ERS related proteins were measured by RT-qPCR and western blot.

KEY RESULTS

The PE-serum treatment on HTR-8/SVneo cells led to activated ERS and suppressed cell biological functions. PE mouse models after MT treatment or 4-PBA treatment had reduced blood pressure, proteinuria, apoptosis and increased foetus and placenta weight, in addition to enhanced cell infiltration.

CONCLUSIONS

In vivo and in vitro evidence demonstrated MT can simultaneously suppress ERS and ASK1/JNK signal pathway in PE to promote the infiltration of trophoblasts.

Daemonorops draco Blume Induces Apoptosis Against Acute Myeloid Leukemia Cells via Regulation of the miR-216b/c-Jun

Daemonorops draco Blume (DD), also called dragon’s blood, has been used as a traditional Korean medicine, especially for relieving pain caused by wound infection. Recently, it has been described that DD has antibacterial and analgesic effects. In this study, the underlying anticancer effect of DD associated with apoptosis was investigated in acute myeloid leukemia cell lines U937 and THP-1. DD exhibited cytotoxic effects and induced apoptosis in U937 and THP-1 cells. Moreover, DD treatment significantly reduced mitochondrial membrane potential (ΔΨ). The protein expression of cleaved poly(ADP-ribose) polymerase, cleaved caspase-3, p-H2A.X, CCAAT/enhancer-binding protein (CHOP), and activating transcription factor 4 was upregulated by DD treatment. Consistently, DD-treated cells had increased reactive oxygen species (ROS) level in a concentration-dependent manner via miR-216b activation in association with c-Jun inhibition. N-acetyl-L-cysteine pretreatment reversed the cytotoxic effect of DD treatment as well as prevented ROS accumulation. Collectively, the results of this study suggest that the anticancer effect of DD in AML was mediated by CHOP-dependent apoptosis along with ROS accumulation and included upregulation of miR-216b followed by a decrease in c-Jun.

Crocin ameliorates MicroRNAs-associated ER stress in type 2 diabetes induced by methylglyoxal

OBJECTIVES

Methylglyoxal (MG) provokes endoplasmic reticulum (ER) stress in β-cells and triggers pancreatic β-cell dysfunction. Crocin has anti-diabetic properties. The present study investigated whether crocin prevented pancreas damages induced by MG.

MATERIALS AND METHODS

Diabetes was induced by MG administration (600 mg/kg/day, PO). On the fourteenth day, after proving hyperglycemia, crocin (15, 30, and 60 mg/kg) and metformin (MT) (150 mg/kg) were used for detoxification of MG until the end of the experiment. The animals were divided into 6 groups: 1) control, 2) diabetic by MG, 3) MG + crocin 15 mg/kg, 4) MG + crocin 30 mg/kg, 5) MG + crocin 60 mg/kg, and 6) MG + MT. The data were analyzed by one-way analysis of variance and significant differences were compared by Tukey and Bonferroni tests (P<0.05). Biochemical assays, antioxidant evaluation, and microRNAs expression associated with ER stress were assessed.

RESULTS

MG induced hyperglycemia, insulin resistance, and dyslipidemia (P<0.001). Crocin and MT significantly ameliorated β-cell function through reduction of fasting blood glucose, malondialdehyde levels (P<0.001), and significant elevation of anti-oxidant enzyme activity accompanied by regulation of glutathione and glyoxalase1-Nrf2 in MG induced diabetic mice. Crocin and MT significantly down-regulated microRNAs 204, 216b, 192, and 29a expression (P<0.001). Crocin (60 mg/kg) (P<0.01) and MT (P<0.001) could improve diameter of pancreatic islets in MG treated mice.

CONCLUSION

Crocin prevents the progression of diabetes through modulating ER stress-associated microRNAs and GLO1 activity with the helpful effects of glutathione and Nrf2.

Cytochrome P450 26A1 Modulates the Polarization of Uterine Macrophages During the Peri-Implantation Period

Uterine M1/M2 macrophages activation states undergo dynamic changes throughout pregnancy, and inappropriate macrophages polarization can cause adverse pregnancy outcomes, especially during the peri-implantation period. Our previous studies have confirmed that Cytochrome P450 26A1 (CYP26A1) can affect embryo implantation by regulating uterine NK cells and DCs. The aim of this study was to investigate whether CYP26A1 regulates the polarization of uterine macrophages in early pregnancy. Here, we observed that Cyp26a1 was significantly upregulated in M1 as compared with M2 of uterine macrophages, Raw264.7 and iBMDM. Knockdown of CYP26A1 in mice uterine significantly decreased the number of embryo implantation sites and the proportion of CD45⁺F4/80⁺CD206⁻ M1-like uterine macrophages. Primary uterine macrophages treated with anti-CYP26A1 antibody expressed significantly lower levels of M1 markers Nos2, Il1b, Il6 and Tnf-a. In CYP26A1 knockout Raw264.7 cells, the protein levels of M1 markers TNF-α, IL-6 and CD86 were significantly decreased as compared with the wild type cells. Moreover, CYP26A1 deficiency decreased the ability to produce nitric oxide and increased the phagocytosis capacity of Raw264.7 cells under M1 stimulation state. The re-introduction of CYP26A1 partially reversed the polarization levels of M1 in CYP26A1 knockout Raw264.7 cells. CYP26A1 may regulate the polarization of uterine macrophages to M1 through Stap1 and Slc7a2. In summary, these results indicate that CYP26A1 plays a significant role in macrophage polarization, and knockdown of CYP26A1 can cause insufficient M1 polarization during the peri-implantation period, which has adverse effects on blastocyst implantation.

MicroRNA-216b targets HK2 to potentiate autophagy and apoptosis of breast cancer cells via the mTOR signaling pathway

Patients suffering from breast cancer (BC) still have a poor response to treatments, even though early detection and improved therapy have contributed to a reduced mortality. Recent studies have been inspired on the association between microRNAs (miRs) and therapies of BC. The current study set out to investigate the role of miR-216b in BC, and further analyze the underlining mechanism. Firstly, hexokinase 2 (HK2) and miR-216b were characterized in BC tissues and cells by RT-qPCR and Western blot assay. In addition, the interaction between HK2 and miR-216b was analyzed using dual luciferase reporter assay. BC cells were further transfected with a series of miR-126b mimic or inhibitor, or siRNA targeting HK2, so as to analyze the regulatory mechanism of miR-216b, HK2 and mammalian target of rapamycin (mTOR) signaling pathway, and to further explore their regulation in BC cellular behaviors. The results demonstrated that HK2 was highly expressed and miR-216b was poorly expressed in BC cells and tissues. HK2 was also verified as a target of miR-216b with online databases and dual luciferase reporter assay. Functionally, miR-216b was found to be closely associated with BC progression via inactivating mTOR signaling pathway by targeting HK2. Moreover, cell viability, migration and invasion were reduced as a result of miR-216b upregulation or HK2 silencing, while autophagy, cell cycle arrest and apoptosis were induced. Taken together, our findings indicated that miR-216 down-regulates HK2 to inactivate the mTOR signaling pathway, thus inhibiting the progression of BC. Hence, this study highlighted a novel target for BC treatment.

Comprehensive Analysis of lncRNA and miRNA Regulatory Network Reveals Potential Prognostic Non-coding RNA Involved in Breast Cancer Progression

Breast cancer is one of the most common malignant tumors in women and is the second leading cause of cancer deaths among women. The tumorigenesis and progression of breast cancer are not well understood. The existing researches have indicated that non-coding RNAs, which mainly include long non-coding RNA (lncRNA) and microRNA (miRNA), have gradually become important regulators of breast cancer. We aimed to screen the differential expression of miRNA and lncRNA in the different breast cancer stages and identify the key non-coding RNA using TCGA data. Based on series test of cluster (STC) analysis, bioinformatics analysis, and negatively correlated relationships, 122 lncRNAs, 67 miRNAs, and 119 mRNAs were selected to construct the regulatory network of lncRNA and miRNA. It was shown that the miR-93/20b/106a/106b family was at the center of the regulatory network. Furthermore, 6 miRNAs, 10 lncRNAs, and 15 mRNAs were significantly associated with the overall survival (OS, log-rank P < 0.05) of patients with breast cancer. Overexpressed miR-93 in MCF-7 breast cancer cells was associated with suppressed expression of multiple lncRNAs, and these downregulated lncRNAs (MESTIT1, LOC100128164, and DNMBP-AS1) were significantly associated with poor overall survival in breast cancer patients. Therefore, the miR-93/20b/106a/106b family at the core of the regulatory network discovered by our analysis above may be extremely important for the regulation of lncRNA expression and the progression of breast cancer. The identified key miRNA and lncRNA will enhance the understanding of molecular mechanisms of breast cancer progression. Targeting these key non-coding RNA may provide new therapeutic strategies for breast cancer treatment and may prevent the progression of breast cancer from an early stage to an advanced stage.

Thyroid hormone synthesis continues despite biallelic thyroglobulin mutation with cell death

Complete absence of thyroid hormone is incompatible with life in vertebrates. Thyroxine is synthesized within thyroid follicles upon iodination of thyroglobulin conveyed from the endoplasmic reticulum (ER), via the Golgi complex, to the extracellular follicular lumen. In congenital hypothyroidism from biallelic thyroglobulin mutation, thyroglobulin is misfolded and cannot advance from the ER, eliminating its secretion and triggering ER stress. Nevertheless, untreated patients somehow continue to synthesize sufficient thyroxine to yield measurable serum levels that sustain life. Here, we demonstrate that TG^{W2346R/W2346R} humans, TG^cog/cog mice, and TG^rdw/rdw rats exhibited no detectable ER export of thyroglobulin, accompanied by severe thyroidal ER stress and thyroid cell death. Nevertheless, thyroxine was synthesized, and brief treatment of TG^rdw/rdw rats with antithyroid drug was lethal to the animals. When untreated, remarkably, thyroxine was synthesized on the mutant thyroglobulin protein, delivered via dead thyrocytes that decompose within the follicle lumen, where they were iodinated and cannibalized by surrounding live thyrocytes. As the animals continued to grow goiters, circulating thyroxine increased. However, when TG^rdw/rdw rats age, they cannot sustain goiter growth that provided the dying cells needed for ongoing thyroxine synthesis, resulting in profound hypothyroidism. These results establish a disease mechanism wherein dead thyrocytes support organismal survival.

Cell death-associated lipid droplet protein CIDE-A is a noncanonical marker of endoplasmic reticulum stress

Secretory protein misfolding has been linked to ER stress and cell death. We expressed a TGrdw transgene encoding TG-G(2298)R, a misfolded mutant thyroglobulin reported to be linked to thyroid cell death. When the TGrdw transgene was expressed at low level in thyrocytes of TGcog/cog mice that experienced severe ER stress, we observed increased thyrocyte cell death and increased expression of CIDE-A (cell death-inducing DFFA-like effector-A, a protein of lipid droplets) in whole thyroid gland. Here we demonstrate that acute ER stress in cultured PCCL3 thyrocytes increases Cidea mRNA levels, maintained at least in part by increased mRNA stability, while being negatively regulated by activating transcription factor 6 - with similar observations that ER stress increases Cidea mRNA levels in other cell types. CIDE-A protein is sensitive to proteasomal degradation yet is stabilized by ER stress, and elevated expression levels accompany increased cell death. Unlike acute ER stress, PCCL3 cells adapted and surviving chronic ER stress maintained a disproportionately lower relative mRNA level of Cidea compared with that of other, classical ER stress markers, as well as a blunted Cidea mRNA response to a new, unrelated acute ER stress challenge. We suggest that CIDE-A is a novel marker linked to a noncanonical ER stress response program, with implications for cell death and survival.

Noncoding RNAs: modulators and modulatable players during infection-induced stress response

The human genome has an almost equal distribution of unique and transposable genetic elements. Although at the transcriptome level, a relatively higher contribution from transposable elements derived RNA has been reported. This is further highlighted with evidence from pervasive transcription. Of the total RNA, noncoding RNAs (ncRNAs) are significant contributors to the transcriptome pool with sizeable fraction from repetitive elements of the human genome, inclusive of Long Interspersed Nuclear Elements (LINEs) and Short Interspersed Nuclear Elements (SINEs). ncRNAs are increasingly being implicated in diverse functional roles especially during conditions of stress. These stress responses are driven through diverse mediators, inclusive of long and short ncRNAs. ncRNAs such as MALAT1, GAS5, miR-204 and miR-199a-5p have been functionally involved during oxidative stress, endoplasmic reticulum (ER) stress and unfolded protein response (UPR). Also, within SINEs, Alu RNAs derived from primate-specific Alu repeats with ~11% human genome contribution, playing a significant role. Pathogenic diseases, including the recent COVID-19, leads to differential regulation of ncRNAs. Although, limited evidence suggests the need for an inquest into the role of ncRNAs in determining the host response towards pathogen challenge.

Flufenoxuron suppresses the proliferation of testicular cells by targeting mitochondria in mice

Flufenoxuron is a benzoylurea pesticide that is used to eradicate insects and acarids in the farmland. Even though it specifically works on target animals, the possibilities of its bioaccumulation and harmful effects on non-target animals cannot be denied. As the usage and application of pesticides increases, exposure to them also increases through ingestion of food residues, inhalation, or dermal contact. Pesticides could also be considered as endocrine disruptor chemicals; however, the reproductive toxicity and cellular mechanisms of flufenoxuron have not been identified. Our results indicate that flufenoxuron inhibits cellular proliferation and hampers calcium homeostasis, especially by targeting mitochondria. We also confirmed the induction of endoplasmic reticulum (ER) stress and ER-mitochondrial contact signaling. Using pharmacological inhibitors, we also observed that the mitogen-activated protein kinase and Akt signaling pathways were upregulated by flufenoxuron. Further, by oral administration of flufenoxuron (100 mg/kg/bw) to C57BL/6 male mice, we observed transcriptional changes in the testis-related genes. Collectively, we demonstrated that flufenoxuron inhibits cell proliferation and alters gene expression in mouse testis cells and induces testicular dysfunction in mice. These results indicate that flufenoxuron may be harmful to male reproduction and fertility in the early stages of pregnancy.

Dienogest regulates apoptosis, proliferation, and invasiveness of endometriotic cyst stromal cells via endoplasmic reticulum stress induction

Dienogest, a specific progesterone receptor agonist, is used in the treatment of endometriosis. However, it is still unclear as to the mechanisms of therapeutic effects on endometriosis. Our recent study showed that endometriosis may be the result of aberrant endoplasmic reticulum (ER) stress induction due to progesterone resistance. This finding suggests that the regulation of ER stress induction may play a key role in treatment of endometriosis. Therefore, the anti-endometriotic effects of dienogest may be mediated by regulation of ER stress. To test this hypothesis, we elucidate whether dienogest affects endometriotic stromal cell apoptosis, proliferation and invasiveness by modulating ER stress-induced CCAAT/enhancer-binding protein homologous protein (CHOP) expression. Specifically, PRKR-like ER kinase (PERK)/eukaryotic initiation factor 2α (eIF2α)/activating transcription factor 4 (ATF4), inositol-requiring kinase 1 (IRE1)/TNF receptor-associated factor 2 (TRAF2)/apoptosis signal-regulating kinase 1 (ASK1)/c-Jun N-terminal kinase (JNK) signaling, and downstream CHOP were evaluated to determine the involved ER stress-mediated regulation mechanism of CHOP expression. Our results show that progesterone treatment did not have any significant effects on ER stress, apoptosis, proliferation, and invasion in estrogen-treated endometriotic cyst stromal cells (ECSCs). However, dienogest treatment upregulated the induction of ER stress. It also led to increased apoptosis, and decreased proliferation and invasiveness. These dienogest-induced changes in apoptosis, proliferation and invasiveness were reversed by the ER stress inhibitor salubrinal. Furthermore, dienogest-induced ER stress increased CHOP expression through activation of both PERK/elf2α/ATF4 and IRE1/TRAF2/ASK1/JNK signaling. This upregulation was blocked by transfection with PERK and IRE1 siRNA, which decreased apoptosis and increased the proliferation and invasiveness of dienogest-treated ECSCs. Taken together, our findings indicate that dienogest enhances ER stress induction in endometriotic stromal cells, which affects apoptosis, proliferation and invasiveness via CHOP upregulation.

MicroRNA and ER stress in cancer

The development of biological technologies in genomics, proteomics, and bioinformatics has led to the identification and characterization of the complete set of coding genes and their roles in various cellular pathways in cancer. Nevertheless, the cellular pathways have not been fully figured out like a jigsaw puzzle with missing pieces. The discovery of noncoding RNAs including microRNAs (miRNAs) has provided the missing pieces of the cellular pathways. Likewise, miRNAs have settled many questions of inexplicable patches in the endoplasmic reticulum (ER) stress pathways. The ER stress-caused pathways typified by the unfolded protein response (UPR) are pivotal processes for cellular homeostasis and survival, rectifying uncontrolled proteostasis and determining the cell fate. Although various factors and pathways have been studied and characterized, the understanding of the ER stress requires more wedges to fill the cracks of knowledge about the ER stress pathways. Moreover, the roles of the ER stress and UPR are still controversial in cancer despite their strong potential to promote cancer. The noncoding RNAs, in particular, miRNAs aid in a better understanding of the ER stress and its role in cancer. In this review, miRNAs that are the more-investigated subtype of noncoding RNAs are focused on the interpretation of the ER stress in cancer, following the introduction of miRNA and ER stress.

Dysregulation of lnc-SNHG1 and miR-216b-5p correlate with chemoresistance and indicate poor prognosis of serous epithelial ovarian cancer

Aim

This study aimed to explore whether the dysregulation of lnc-small nucleolar RNA host gene 1 (SNHG1) and miR-216b-5p correlated with chemoresistance and indicated poor prognosis of serous epithelial ovarian cancer (EOC).

Methods and results

The expression of lnc-SNHG1 was upregulated, while miR-216b-5p showed low expression in patients with chemoresistant EOC compared with patients with chemosensitive EOC. The multivariate Cox regression analysis showed that the expression of miR-216b-5p and FIGO stage were independent prognostic factors for the overall survival (OS) of patients with serous EOC. Kaplan–Meier curves revealed a significant association of the increased expression level of lnc-SNHG1 with shorter OS and disease-free survival (DFS). Patients with a low expression level of miR-216b-5p also had shorter OS and DFS. The biological functions were tested using CCK-8 assay, colony formation assay, wound healing assay, and cell apoptosis. The knockdown of SNHG1 and the overexpression of miR-216b-5p stimulated paclitaxel sensitivity in A2780/Taxol cells through inhibiting cell growth and migration and promoting apoptosis. The inhibition of miR-216b-5p could rescue the effect of lnc-SNHG1 inhibition on the sensitivity of A2780/Taxol cells to paclitaxel. Luciferase reporter assay, RNA Binding Protein Immunoprecipitation Assay (RIP), and quantitative reverse transcription–polymerase chain reaction (qRT-PCR) indicated that lnc-SNHG1 acted as a sponge of miR-216b-5p in A2780/Taxol cells.

Conclusions

This study showed that the overexpression of lnc-SNHG1 and decreased expression level of miR-216b-5p correlated with the chemoresistance of patients with serous EOC and indicated shorter OS and DFS. Lnc-SNHG1 functioned as a ceRNA with miR-216b-5p, which was critical in modulating the paclitaxel sensitivity of ovarian cancer cells.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13048-020-00750-4.

Exosomes Derived from Human Urine-Derived Stem Cells Inhibit Intervertebral Disc Degeneration by Ameliorating Endoplasmic Reticulum Stress

Objective

This study is aimed at determining the effects of human urine-derived stem cell-derived exosomes (USCs-exos) on pressure-induced nucleus pulposus cell (NPC) apoptosis and intervertebral disc degeneration (IDD) and on the ERK and AKT signaling pathways.

Methods

The NPCs were obtained from patients with herniated lumbar discs. Western blot analysis (WB) and quantitative real-time polymerase chain reaction (qRT-PCR) were used to determine endoplasmic reticulum (ER) stress levels of NPCs under stress. Human USCs were identified using an inverted microscope, three-line differentiation experiments, and flow cytometry. A transmission microscope, nanoparticle size analysis, and WB procedures were used to identify the extracted exosomes and observe NPC uptake. A control group, a 48 h group, and a USCs-exos group were established. The control group was untreated, and the 48 h group was pressure-trained for 48 h, while the USCs-exos group was pressure-trained for 48 h and treated with USCs-exos. WB, qRT-PCR, and terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) analysis were used to determine the ER stress levels in stress conditions and after exosomal treatment. The AKT and ERK pathways were partially detected. Magnetic Resonance Imaging (MRI) and computed tomography (CT) were used to evaluate cell degeneration while exosomal effects on the intervertebral disc (IVD) tissue were determined by hematoxylin and eosin (HE) staining, Safranin O-fast green staining, immunohistochemical staining (IHC), nuclear magnetic resonance (NMR), spectrometric detection, and total correlation spectroscopy (TOCSY). IVD metabolites were also identified and quantified.

Results

After pressure culture, ER stress markers (GRP78 and C/EBP homologous protein (CHOP)) in the NPCs were significantly elevated with time (p < 0.05). Human USCs are short and spindle-shaped. They can successfully undergo osteogenic, adipogenic, and chondrogenic differentiation. In this study, these stem cells were found to be positive for CD29, CD44, and CD73. The exosomes were centrally located with a diameter of 50-100 nm. CD63 and Tsg101 were highly expressed while the expression of Calnexin was suppressed. The exosomes can be ingested by NPCs. USCs-exos significantly improved ER stress responses and inhibited excessive activation of the unfolded protein response (UPR) as well as cell apoptosis and disc degeneration through the AKT and ERK signaling pathways (p < 0.05).

Conclusion

Through the AKT and ERK signaling pathways, USCs-exos significantly inhibit ER stress-induced cell apoptosis and IDD under pressure conditions. It is, therefore, a viable therapeutic strategy.

Interplay between endoplasmic reticulum stress and non-coding RNAs in cancer

To survive, cancer cells are subjected to various internal and external adverse factors, including genetic mutations, hypoxia, nutritional deficiencies, and drug toxicity. All of these factors result in the accumulation of unfolded proteins in the endoplasmic reticulum, which leads to a condition termed endoplasmic reticulum stress (ER stress) and triggers the unfolded protein response (UPR). UPR downstream components strictly control transcription and translation reprogramming to ensure selective gene expression, including that of non-coding RNA (ncRNAs), to adapt to adverse environments. NcRNAs, including microRNAs (miRNAs), long non-coding RNAs (lncRNAs), and circular RNAs (circRNAs), play important roles in regulating target gene expression and protein translation, and their aberrant expression is related to tumor development. Dysregulation of ncRNAs is involved in the regulation of various cellular characteristics of cancer cells, including growth, apoptosis, metastasis, angiogenesis, drug sensitivity, and tumor stem cell properties. Notably, ncRNAs and ER stress can regulate each other and collaborate to determine the fate of tumor cells. Therefore, investigating the interaction between ER stress and ncRNAs is crucial for developing effective cancer treatment and prevention strategies. In this review, we summarize the ER stress-triggered UPR signaling pathways involved in carcinogenesis followed by the mutual regulation of ER stress and ncRNAs in cancer, which provide further insights into the understanding of tumorigenesis and therapeutic strategies.

Endoplasmic Reticulum Stress Provocation by Different Nanoparticles: An Innovative Approach to Manage the Cancer and Other Common Diseases

A proper execution of basic cellular functions requires well-controlled homeostasis including correct protein folding. Endoplasmic reticulum (ER) implements such functions by protein reshaping and post-translational modifications. Different insults imposed on cells could lead to ER stress-mediated signaling pathways, collectively called the unfolded protein response (UPR). ER stress is also closely linked with oxidative stress, which is a common feature of diseases such as stroke, neurodegeneration, inflammation, metabolic diseases, and cancer. The level of ER stress is higher in cancer cells, indicating that such cells are already struggling to survive. Prolonged ER stress in cancer cells is like an Achilles' heel, if aggravated by different agents including nanoparticles (NPs) may be exhausted off the pro-survival features and can be easily subjected to proapoptotic mode. Different types of NPs including silver, gold, silica, graphene, etc. have been used to augment the cytotoxicity by promoting ER stress-mediated cell death. The diverse physico-chemical properties of NPs play a great role in their biomedical applications. Some special NPs have been effectively used to address different types of cancers as these particles can be used as both toxicological or therapeutic agents. Several types of NPs, and anticancer drug nano-formulations have been engineered to target tumor cells to enhance their ER stress to promote their death. Therefore, mitigating ER stress in cancer cells in favor of cell death by ER-specific NPs is extremely important in future therapeutics and understanding the underlying mechanism of how cancer cells can respond to NP induced ER stress is a good choice for the development of novel therapeutics. Thus, in depth focus on NP-mediated ER stress will be helpful to boost up developing novel pro-drug candidates for triggering pro-death pathways in different cancers.

miR-96-5p attenuates malathion-induced apoptosis of human kidney cells by targeting the ER stress marker DDIT3

Micro RNAs (miRNAs) are major players in cellular responses to xenobiotic compounds and toxins. However, their functions in organophosphate-induced cytotoxicity remain unclear. This study investigated the involvement of miR-96-5p in the non-cholinergic toxicity of malathion in normal human kidney cells (HK-2 cells). Malathion decreased HK-2 cell viability and the expression of miR-96-5p in a dose- and time-dependent manner. In addition, transfection with miR-96-5p mimics attenuated malathion-induced HK-2 cell apoptosis, whereas transfection with a miR-96-5p inhibitor increased HK-2 cell apoptosis. Luciferase assays indicated that miR-96-5p could bind directly to the 3'-untranslated region of DDIT3, a well-known marker of endoplasmic reticulum stress. Further analyses of the expression of apoptosis-related genes and proteins indicated that miR-96-5p may function to reduce malathion-induced HK-2 cell apoptosis via regulation of the DDIT3/B-cell lymphoma (BCL)-2/caspase-3 signaling pathway. In summary, the results of the present study indicate that miR-96-5p protects HK-2 cells from malathion-induced ER stress-dependent apoptosis by targeting DDIT3.

Regulation of microRNAs by IRE1α in apoptosis: implications for the pathomechanism of neurodegenerative diseases

Although there are large differences in clinical and pathological features, age-related neurodegenerative diseases (NDs) share common pathogenetic mechanisms involving aggregation and deposition of misfolded proteins, which leads to progressive dysfunction and death of neurons. Up to now, it seems that apoptosis is one major form of neuronal cell death. This review provides an overview of recent progress in unfolded protein response (UPR) during apoptosis induced by abnormal protein aggregation and emphasizes on the potential role of inositol requiring enzyme 1 alpha (IRE1α)-microRNAs (miRNAs) mediated apoptosis in NDs, which will provide new insights in the pathogenesis of neurodegenerative diseases and novel therapeutic targets for the treatment of NDs.

PERK-mediated induction of microRNA-483 disrupts cellular ATP homeostasis during the unfolded protein response

Endoplasmic reticulum (ER) stress activates the unfolded protein response (UPR), which reduces levels of misfolded proteins. However, if ER homeostasis is not restored and the UPR remains chronically activated, cells undergo apoptosis. The UPR regulator, PKR-like endoplasmic reticulum kinase (PERK), plays an important role in promoting cell death when persistently activated; however, the underlying mechanisms are poorly understood. Here, we profiled the microRNA (miRNA) transcriptome in human cells exposed to ER stress and identified miRNAs that are selectively induced by PERK signaling. We found that expression of a PERK-induced miRNA, miR-483, promotes apoptosis in human cells. miR-483 induction was mediated by a transcription factor downstream of PERK, activating transcription factor 4 (ATF4), but not by the CHOP transcription factor. We identified the creatine kinase brain-type (CKB) gene, encoding an enzyme that maintains cellular ATP reserves through phosphocreatine production, as being repressed during the UPR and targeted by miR-483. We found that ER stress, selective PERK activation, and CKB knockdown all decrease cellular ATP levels, leading to increased vulnerability to ER stress-induced cell death. Our findings identify miR-483 as a downstream target of the PERK branch of the UPR. We propose that disruption of cellular ATP homeostasis through miR-483-mediated CKB silencing promotes ER stress-induced apoptosis.

Butylated hydroxytoluene induces dysregulation of calcium homeostasis and endoplasmic reticulum stress resulting in mouse Leydig cell death

Butylated hydroxytoluene (BHT) is a synthetic phenolic antioxidant that has been used as an additive for fat- or oil-containing foods. The exposure index value increases with extended usage of the chemical. Further, estimated total amount of BHT could exceed standard regulation, considering dietary intake or another exposure. Although BHT may induce side effects in reproductive systems, adequate research had not yet been performed to confirm them. In this study, we investigated the effects of BHT on mouse Leydig cells (TM3), which are components of testis. Our results indicated that BHT suppressed cellular proliferation and induced cell cycle arrest in TM3 cells. Moreover, BHT hampered cytosolic and mitochondrial calcium homeostasis in TM3 cells. Furthermore, BHT treatment led to endoplasmic reticulum (ER) stress and DNA fragmentation, simultaneously stimulating intrinsic apoptosis signal transduction. To elucidate the mode of action of BHT on Leydig cells, we performed western blot analysis and confirmed the activation of the PI3K/AKT and MAPK pathways. Collectively, our results demonstrated that BHT has toxic effects on mouse Leydig cells via induction of calcium dysregulation and ER-mitochondria dysfunction.

ROR2 induces cell apoptosis via activating IRE1α/JNK/CHOP pathway in high-grade serous ovarian carcinoma in vitro and in vivo

Background

Epithelial ovarian cancer (EOC) is the most lethal cancer in female genital tumors. New disease markers and novel therapeutic strategies are urgent to identify considering the current status of treatment. Receptor tyrosine kinases family plays critical roles in embryo development and disease progression. However, ambivalent research conclusions of ROR2 make its role in tumor confused and the underlying mechanism is far from being understood. In this study, we sought to clarify the effects of ROR2 on high-grade serous ovarian carcinoma (HGSOC) cells and reveal the mechanism.

Methods

Immunohistochemistry assay and western-blot assay were used to detect proteins expression. ROR2 overexpression adenovirus and Lentivirus were used to create ROR2 overexpression model in vitro and in vivo, respectively. MTT assay, colony formation assay and transwell assay were used to measure the proliferation, invasion and migration ability of cancer cells. Flow cytometry assay was used to detect cell apoptosis rate. Whole transcriptome analysis was used to explore the differentially expressed genes between ROR2 overexpression group and negative control group. SiRNA targeted IRE1α was used to knockdown IRE1α. Kira6 was used to inhibit phosphorylation of IRE1α.

Results

Expression of ROR2 was significantly lower in HGSOC tissues compared to normal fallopian tube epithelium or ovarian surface epithelium tissues. In HGSOC cohort, patients with advanced stages or positive lymph nodes were prone to express lower ROR2. Overexpression of ROR2 could repress the proliferation of HGSOC cells and induce cell apoptosis. RNA sequencing analysis indicated that ROR2 overexpression could induce unfold protein response. The results were also confirmed by upregulation of BIP and phosphorylated IRE1α. Furthermore, pro-death factors like CHOP, phosphorylated JNK and phosphorylated c-Jun were also upregulated. IRE1α knockdown or Kira6 treatment could reverse the apoptosis induced by ROR2 overexpression. Finally, tumor xenograft experiment showed ROR2 overexpression could significantly repress the growth rate and volume of transplanted tumors.

Conclusions

Taken together, ROR2 downregulation was associated with HGSOC development and progression. ROR2 overexpression could repress cell proliferation and induce cell apoptosis in HGSOC cells. And the underlying mechanism might be the activation of IRE1α/JNK/CHOP pathway induced by ROR2.

Endoplasmic Reticulum Stress Induces miR-706, A Pro-Cell Death microRNA, in A Protein Kinase RNA-Like ER Kinase (PERK) and Activating Transcription Factor 4 (ATF4) Dependent Manner

Objective

Endoplasmic reticulum (ER) stress causes an adaptive response initiated by protein kinase RNA-like ER kinase (PERK), Ire1 and ATF6. It has been reported that these upstream regulators induce microRNAs. The current study was designed to find a novel microRNA that mediates ER stress components and finally contributes to cell fate decision.

Materials and Methods

In this experimental study, miR-706 levels were checked under different conditions of ER stress induced by Thapsigargin, Tunicamycin or low glucose media. PERK and ATF4 were knocked-down by administration of lentivirus-mediated short hairpin RNA to explore the effect of ER stress related proteins on miR-706 expression. The effect of miR-706 on caspase activity and apoptosis inhibitor 1 (CAAP1) levels were examined by using mimic-miR-706. The role of CAAP1 in inhibiting cell death (measured by Annexin V staining) and contributing to patient overall survival (measured by Kaplan-Meier estimate) were further confirmed by anti- miR-706 and CAAP1 knock-down.

Results

We showed that Thapsigargin or Tunicamycin triggered ER stress leading to the induction of miR-706. miR-706 induction is dependent on PERK and its downstream regulator ATF4, as knocking-down of PERK and ATF4 suppressed miR-706 induction in response to ER stress. Knocking-down of miR-706 reduces cell death triggered by ER stress, indicating that miR-706 is pro-cell death microRNA. We further identified CAAP1 as a miR-706 target in regulating ER stress initiated cell death.

Conclusion

Collectively, our results pointed to an ER signaling network consisting of proteins, microRNA and novel target.

H19 promote calcium oxalate nephrocalcinosis-induced renal tubular epithelial cell injury via a ceRNA pathway

Background

Intrarenal calcium oxalate (CaOx) crystals induce inflammation and kidney tubular cell injury, which are processes that involve TLR4/NF-κB signalling. A recent genome-wide gene expression profile analysis of Randall's plaques in CaOx stone patients revealed that the expression of the long noncoding RNA H19 was significantly upregulated. However, to date, its role in kidney CaOx stones has not been reported.

Method

A Gene Expression Omnibus (GEO) dataset was utilized to analyse gene expression profiles. Luciferase reporter, Western blotting, qRT-PCR, immunofluorescence staining and reactive oxygen species (ROS) assays were employed to study the molecular mechanism of HMGB1/TLR4/NF-κB regulation by H19 and miR-216b. In vitro and in vivo assays were performed to further confirm the proinflammatory and prooxidative stress effects.

Finding

H19 expression was significantly increased and positively correlated with the expression levels of HMGB1, TLR4 and NF-κB in Randall's plaques and glyoxylate-induced CaOx nephrocalcinosis mouse models. H19 interacted with miR-216b and suppressed its expression. Additionally, miR-216b inhibited HMGB1 expression by directly binding its 3′-untranslated region. Moreover, H19 downregulation inhibited HMGB1, TLR4 and NF-κB expression and suppressed CaOx nephrocalcinosis-induced renal tubular epithelial cell injury, NADPH oxidase, and oxidative stress in vivo and in vitro. Interestingly, miR-216b inhibition partially reversed the inhibitory effect of H19 knockdown on HMGB1 expression.

Interpretation

We determined that H19 might serve as a facilitator in the process of CaOx nephrocalcinosis-induced oxidative stress and renal tubular epithelial cell injury, and we revealed that the interaction between H19 and miR-216b could exert its effect via the HMGB1/TLR4/NF-κB pathway.

Funding

This work was supported by the National Nature Science Foundation of China (Nos. 8196030190, 8190033175, 81370805, 81470935, 81900645, 81500534, and 81602236).

Targeting the IL-1β/IL-1Ra pathways for the aggregation of human islet amyloid polypeptide in an ex vivo organ culture system of the intervertebral disc

Intervertebral disc degeneration (IDD) is characterized by excessive apoptosis of nucleus pulposus (NP) cells and hyperactive extracellular matrix (ECM) catabolism. Our previous studies revealed the relationship between human islet amyloid polypeptide (hIAPP) and NP cell apoptosis. However, the role of hIAPP aggregates in IDD has not yet been investigated. This study aimed to determine whether the accumulation of hIAPP aggregates promotes IDD progression. The aggregation of hIAPP increased in human NP tissues during IDD. The deposition of hIAPP aggravated the compression-induced IDD that promoted NP cell apoptosis and ECM degradation via IL-1β/IL-1Ra signaling in an ex vivo rat disc model. Moreover, neutralizing IL-1β augmented the protective effects of hIAPP overexpression by decreasing hIAPP aggregation in human NP cells. These results suggest that the aggregation of hIAPP promotes NP cell apoptosis and ECM degradation ex vivo and in vitro by disrupting the balance of IL-1β/IL-1Ra signaling.

Exosomes from mesenchymal stem cells modulate endoplasmic reticulum stress to protect against nucleus pulposus cell death and ameliorate intervertebral disc degeneration in vivo

Objectives: Intervertebral disc degeneration (IDD) is widely accepted as a cause of low back pain and related degenerative musculoskeletal disorders. Nucleus pulposus (NP) cell apoptosis which is related to excessive endoplasmic reticulum (ER) stress in the intervertebral disc (IVD) could aggravate IDD progression. Many studies have shown the therapeutic potential of exosomes derived from bone marrow mesenchymal stem cells (MSC-exos) in degenerative diseases. We hypothesized that the delivery of MSC-exos could modulate ER stress and inhibit excessive NP cell apoptosis during IDD.

Methods: The ER stress levels were measured in normal or degenerative NP tissues for contrast. The effects of MSC-exos were testified in advanced glycation end products (AGEs) -induced ER stress in human NP cells. The mechanism involving AKT and ERK signaling pathways was investigated using RNA interference or signaling inhibitors. Histological or immunohistochemical analysis and TUNEL staining were used for evaluating MSC-exos therapeutic effects in vivo.

Results: The ER stress level and apoptotic rate was elevated in degenerative IVD tissues. MSC-exos could attenuate ER stress-induced apoptosis by activating AKT and ERK signaling. Moreover, delivery of MSC-exos in vivo modulated ER stress-related apoptosis and retarded IDD progression in a rat tail model.

Conclusions: These results highlight the therapeutic effects of exosomes in preventing IDD progression. Our work is the first to demonstrate that MSC-exos could modulate ER stress-induced apoptosis during AGEs-associated IVD degeneration.

Heme Oxygenase-1 Inhibition Sensitizes Human Prostate Cancer Cells towards Glucose Deprivation and Metformin-Mediated Cell Death

High levels of heme oxygenase (HO)-1 have been frequently reported in different human cancers, playing a major role in drug resistance and regulation of cancer cell redox homeostasis. Metformin (MET), a drug widely used for type 2 diabetes, has recently gained interest for treating several cancers. Recent studies indicated that the anti-proliferative effects of metformin in cancer cells are highly dependent on glucose concentration. The present work was directed to determine whether use of a specific inhibitor of HO-1 activity, alone or in combination with metformin, affected metastatic prostate cancer cell viability under different concentrations of glucose. MTT assay and the xCELLigence system were used to evaluate cell viability and cell proliferation in DU145 human prostate cancer cells. Cell apoptosis and reactive oxygen species were analyzed by flow cytometry. The activity of HO-1 was inhibited using a selective imidazole-based inhibitor; genes associated with antioxidant systems and cell death were evaluated by qRT-PCR. Our study demonstrates that metformin suppressed prostate cancer growth in vitro and increased oxidative stress. Disrupting the antioxidant HO-1 activity, especially under low glucose concentration, could be an attractive approach to potentiate metformin antineoplastic effects and could provide a biochemical basis for developing HO-1-targeting drugs against solid tumors.

The PKR-Like Endoplasmic Reticulum Kinase Promotes the Dissemination of Myc-Induced Leukemic Cells

Hyperactive oncogenic Myc stimulates protein synthesis that induces the unfolded protein response, which requires the function of the eukaryotic translation initiation factor 2-alpha kinase 3, also known as protein kinase R (PKR)-like endoplasmic reticulum kinase (PERK). Activated PERK acts to limit mRNA translation, enable proper protein folding, and restore the homeostasis in the endoplasmic reticulum. Given that Myc activation contributes to many types of lymphoid and myeloid human leukemias, we used a mouse model to examine the importance of PERK in development and progression of Myc-induced leukemias. We found that genetic ablation of Perk does not suppress the generation of the leukemic cells in the bone marrow. However, the cell-autonomous Perk deficiency restricts the dissemination of leukemic cells into peripheral blood, lymph nodes, and vital peripheral organs. Whereas the loss of the IFNAR1 chain of type I IFN receptor stimulated leukemia, Perk ablation did not stabilize IFNAR1, suggesting that PERK stimulates the leukemic cells' dissemination in an IFNAR1-independent manner. We discuss the rationale for using PERK inhibitors against Myc-driven leukemias. IMPLICATIONS: The role of PERK in dissemination of Myc-induced leukemic cells demonstrated in this study argues for the use of PERK inhibitors against leukemia progression.

Low glucose and metformin-induced apoptosis of human ovarian cancer cells is connected to ASK1 via mitochondrial and endoplasmic reticulum stress-associated pathways

Background

Metformin, a first-line drug for type 2 diabetes, could induce apoptosis in cancer cells. However, the concentration of glucose affects the effect of metformin, especially low glucose in the culture medium can enhance the cytotoxicity of metformin on cancer cells. Since mitochondria and endoplasmic reticulum is vital for maintaining cell homeostasis, we speculate that low glucose and metformin-induced cell apoptosis may be associated with mitochondria and endoplasmic reticulum. ASK1, as apoptosis signaling regulating kinase 1, is associated with cell apoptosis and mitochondrial damage. This study was designed to investigate the functional significance of ASK1, mitochondria and endoplasmic reticulum and underlying mechanism in low glucose and metformin-induced cell apoptosis.

Methods

An MTT assay was used to evaluate cell viability in SKOV3, OVCAR3 and HO8910 human ovarian cancer cells. Cell apoptosis was analyzed by flow cytometry. The expression of ASK1 was inhibited using a specific pharmacological inhibitor or ASK1-siRNA. Immunofluorescence was used to detect mitochondrial damage and ER stress. Nude mouse xenograft models were given metformin or/and NQDI-1, and ASK1 expression was detected using immunoblotting. In addition, subcellular fractionation of mitochondria was performed to assay the internal connection between ASK1 and mitochondria.

Results

The present study found that low glucose in culture medium enhanced the anticancer effect of metformin in human ovarian cancer cells. Utilization of a specific pharmacological inhibitor or ASK1-siRNA identified a potential role for ASK1 as an apoptotic protein in the regulation of low glucose and metformin-induced cell apoptosis via ASK1-mediated mitochondrial damage through the ASK1/Noxa pathway and via ER stress through the ROS/ASK1/JNK pathway. Moreover, ASK1 inhibition weakened the antitumor activity of metformin in vivo. Thus, mitochondrial damage and ER stress play a crucial role in low glucose–enhanced metformin cytotoxicity in human ovarian cancer cells.

Conclusions

These data suggested that low glucose and metformin induce cell apoptosis via ASK1-mediated mitochondrial damage and ER stress. These findings indicated that the effect of metformin in anticancer treatment may be related to cell culture conditions.

Angelica gigas Nakai Has Synergetic Effects on Doxorubicin-Induced Apoptosis

Natural products are valuable sources for drug discovery because they have a wide variety of useful chemical components and biological properties. A quick reevaluation of the potential therapeutic properties of established natural products was made possible by the recent development of the methodology and improvement in the accuracy of an automated high-throughput screening system. In this study, we screened natural product libraries to detect compounds with anticancer effects using HeLa cells. Of the 420 plant extracts screened, the extract of Angelica gigas Nakai (AGN) was the most effective in reducing cell viability of HeLa cells. Markers of apoptosis, such as exposure of phosphatidylserine and cleavage of caspase-7 and PARP, were increased by treatment with the AGN extract. Treatment of the AGN extract increased expression of PKR as well as ATF4 and CHOP, the unfolded protein response genes. In addition, cotreatment of doxorubicin and the AGN extract significantly increased doxorubicin-induced apoptosis in HeLa cells. Decursin and decursinol angelate, which were known to have anticancer effects, were the main components of the AGN extract. These results suggest that the extract of AGN containing, decursin and decursinol angelate, increases doxorubicin susceptibility.

Kaempferol induces autophagic cell death via IRE1-JNK-CHOP pathway and inhibition of G9a in gastric cancer cells

Kaempferol, a flavonoid, found in traditional medicine, fruits, and vegetables, and an HDAC inhibitor, is a powerful anti-cancer reagent against various cancer cell lines. However, detailed mechanisms involved in the treatment of gastric cancer (GC) using kaempferol are not fully understood. In our study, we investigated the biological activity and molecular mechanism involved in kaempferol-mediated treatment of GC. Kaempferol promoted autophagy and cell death, and increased LC3-I to LC3-II conversion and the downregulation of p62 in GC. Furthermore, our results showed that kaempferol induces autophagic cell death via the activation of the IRE1-JNK-CHOP signaling, indicating ER stress response. Indeed, the inhibition of ER stress suppressed kaempferol-induced autophagy and conferred prolonged cell survival, indicating autophagic cell death. We further showed that kaempferol mediates epigenetic change via the inhibition of G9a (HDAC/G9a axis) and also activates autophagic cell death. Taken together, our findings indicate that kaempferol activates the IRE1-JNK-CHOP signaling from cytosol to nucleus, and G9a inhibition activates autophagic cell death in GC cells.

Activation of ER Stress-Dependent miR-216b Has a Critical Role in Salviamiltiorrhiza Ethanol-Extract-Induced Apoptosis in U266 and U937 Cells

Although Salviamiltiorrhiza has been reported to have anti-cancer mechanisms, such as caspase activation, cell cycle arrest, an anti-angiogenesis effect, and Bcl-2 family regulation, its underlying mechanism of endoplasmic reticulum (ER) stress-mediated apoptosis has never been demonstrated. Thus, in this current study, ER stress-related apoptosis via miR-216b of the ethanol extract of Salviamiltiorrhiza (SM) is elucidated for the first time. SM treatment inhibited the viability of U266 and U937 cells in a concentration-dependent manner. However, SM-exposed Raw264.7 cells were intact compared to U266 or U937 cells. Treatment with SM significantly elevated the generation of reactive oxygen species (ROS). The anti-proliferative effect of SM was reversed by pretreatment with the ROS scavenger, N-acetyl-l-cysteine (NAC), compared to cells treated only with SM. Also, SM treatment increased the ER stress by elevation of phosphorylated activating transcription factor 4 (p-ATF4), phosphorylated eukaryotic Initiation Factor 2 (p-eIF2), and phosphorylated protein kinase RNA-like endoplasmic reticulum kinase (p-PERK) expression. Caspase-3 and Poly (ADP-ribose) polymerase (PARP) were cleaved and CCAAT-enhancer-binding protein homologous protein (CHOP) was activated by SM treatment. PARP cleavage and CHOP activation were attenuated by NAC pretreatment. Furthermore, SM increased the tumor suppressor, miR-216b, and suppressed its target, c-Jun. miR-216b inhibitor attenuated the apoptotic effect of SM. Taken together, SM treatment induced apoptosis through regulation of miR-216b and ROS/ER stress pathways. SM could be a potential drug for treatment of multiple myeloma and myeloid leukemia.

MiR-760 suppresses human colorectal cancer growth by targeting BATF3/AP-1/cyclinD1 signaling

Background

Recent studies have reported that microRNAs (miRNAs) often function as negative post-transcriptional regulators with altered expression levels found in colorectal cancer (CRC). There have been few studies on miRNAs that regulate the oncogenic alterations in CRC. Here, we aim to explore the anti-cancer miRNA and the potential mechanisms by which miRNAs modulate CRC progression.

Methods

We performed an integrated analysis of CRC miRNA expression datasets in The Cancer Genome Atlas (TCGA). The miRNA with the lowest expression, miR-760, was validated in an independent validation sample cohort of 76 CRC tissues. Functional assays, such as CCK-8 assay, colony formation assay, and CFSE staining, were used to determine the oncogenic role of miR-760 in human CRC progression. Furthermore, western blotting and dual-luciferase reporter assay were used to determine the mechanism by which miR-760 promotes proliferation of CRC cells. Xenograft nude mouse models were used to determine the role of miR-760 in CRC tumorigenicity in vivo. Immunohistochemical assays were conducted to study the relationship between miR-760 expression and basic leucine zipper transcriptional factor ATF-like 3 (BATF3) expression in human CRC samples.

Results

miR-760 was markedly downregulated in CRC tissues, and low miR-760 expression was associated with poor prognosis among CRC patients. Upregulation of miR-760 suppressed CRC cell proliferation, whereas downregulation of miR-760 promoted CRC proliferation in vitro. Additionally, we identified BATF3 as a direct target of miR-760, and that the essential biological function of miR-760 during CRC progression both in vitro and in vivo is to suppress the expression of BATF3 and downstream cyclinD1 via AP-1 transcription factor. Finally, we showed a significant correlation between miR-760 and BATF3 expression in CRC tissues.

Conclusions

miR-760 inhibited CRC growth by downregulating BATF3/AP-1/ cyclinD1 signaling.

Electronic supplementary material

The online version of this article (10.1186/s13046-018-0757-8) contains supplementary material, which is available to authorized users.