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Background: Cantharidin (CTD) extracted from the traditional Chinese medicine Mylabris has significant therapeutic effects on various tumors. However, the high toxicity of CTD can cause serious liver damage, although the related molecular mechanisms remain unclear. Methods: In this study, we established models of CTD-induced liver and L-O2 cell damage in mice in vivo and in vitro. Subsequently, liver function indicators were detected in mouse serum, while liver tissues were subjected to pathological and transmission electron microscopy observations. L-O2 cell activity was investigated using the CCK-8 assay, and the mRNA and protein expression of DNA damage-induced transcription factor 4 (DDIT4) in liver tissue and L-O2 cells was detected using qPCR, immunohistochemistry, and western blotting. Western blotting was also used to detect the expression levels of autophagy- and apoptosis-related proteins in liver tissue and L-O2 cells. After RNAi interference with DDIT4, Rap, and 3-MA treatment, autophagy and apoptosis of L-O2 cells were detected using western blotting, flow cytometry, transmission electron microscopy, and confocal microscopy. Results: Following CTD exposure, the mouse liver showed significant pathological damage and an increase in autophagic lysosomes, while the vitality of L-O2 cells showed a significant decrease. CTD led to a significant increase in the mRNA and protein levels of DDIT4 in both liver tissue and L-O2 cells, as well as a significant increase in LC3-II, Beclin1, and Bax, whereas p-mTOR and Bcl-2 were significantly decreased. Following DDIT4 interference and 3-MA treatment, the levels of autophagy and apoptosis induced by CTD in L-O2 cells were reduced. After Rap treatment, both autophagy and apoptosis of CTD-induced L-O2 cells were significantly enhanced. Conclusion: The molecular mechanism of CTD-induced toxicity in mouse liver and L-O2 cells is mainly through DDIT4/mTOR signaling pathway activation, leading to an increase in autophagy and apoptosis levels. [ABSTRACT FROM AUTHOR]

BackgroundCantharidin (CTD) extracted from the traditional Chinese medicine Mylabris has significant therapeutic effects on various tumors. However, the high toxicity of CTD can cause serious liver damage, although the related molecular mechanisms remain unclear.MethodsIn this study, we established models of CTD-induced liver and L-O2 cell damage in mice in vivo and in vitro. Subsequently, liver function indicators were detected in mouse serum, while liver tissues were subjected to pathological and transmission electron microscopy observations. L-O2 cell activity was investigated using the CCK-8 assay, and the mRNA and protein expression of DNA damage-induced transcription factor 4 (DDIT4) in liver tissue and L-O2 cells was detected using qPCR, immunohistochemistry, and western blotting. Western blotting was also used to detect the expression levels of autophagy- and apoptosis-related proteins in liver tissue and L-O2 cells. After RNAi interference with DDIT4, Rap, and 3-MA treatment, autophagy and apoptosis of L-O2 cells were detected using western blotting, flow cytometry, transmission electron microscopy, and confocal microscopy.ResultsFollowing CTD exposure, the mouse liver showed significant pathological damage and an increase in autophagic lysosomes, while the vitality of L-O2 cells showed a significant decrease. CTD led to a significant increase in the mRNA and protein levels of DDIT4 in both liver tissue and L-O2 cells, as well as a significant increase in LC3-II, Beclin1, and Bax, whereas p-mTOR and Bcl-2 were significantly decreased. Following DDIT4 interference and 3-MA treatment, the levels of autophagy and apoptosis induced by CTD in L-O2 cells were reduced. After Rap treatment, both autophagy and apoptosis of CTD-induced L-O2 cells were significantly enhanced.ConclusionThe molecular mechanism of CTD-induced toxicity in mouse liver and L-O2 cells is mainly through DDIT4/mTOR signaling pathway activation, leading to an increase in autophagy and apoptosis levels.

Activation of the transcription factor NF-κB in cardiomyocytes has been implicated in the development of cardiac function deficits caused by diabetes. NF-κB controls the expression of an array of pro-inflammatory cytokines and chemokines. We recently discovered that the stress response protein regulated in development and DNA damage response 1 (REDD1) was required for increased pro-inflammatory cytokine expression in the hearts of diabetic mice. The studies herein were designed to extend the prior report by investigating the role of REDD1 in NF-κB signaling in cardiomyocytes. REDD1 genetic deletion suppressed NF-κB signaling and nuclear localization of the transcription factor in human AC16 cardiomyocyte cultures exposed to TNFα or hyperglycemic conditions. A similar suppressive effect on NF-κB activation and pro-inflammatory cytokine expression was also seen in cardiomyocytes by knocking down the expression of GSK3β. NF-κB activity was restored in REDD1-deficient cardiomyocytes exposed to hyperglycemic conditions by expression of a constitutively active GSK3β variant. In the hearts of diabetic mice, REDD1 was required for reduced inhibitory phosphorylation of GSK3β at S9 and upregulation of IL-1β and CCL2. Diabetic REDD1+/+ mice developed systolic functional deficits evidenced by reduced ejection fraction. By contrast, REDD1−/− mice did not exhibit a diabetes-induced deficit in ejection fraction and left ventricular chamber dilatation was reduced in diabetic REDD1−/− mice, as compared to diabetic REDD1+/+ mice. Overall, the results support a role for REDD1 in promoting GSK3β-dependent NF-κB signaling in cardiomyocytes and in the development of cardiac function deficits in diabetic mice. [ABSTRACT FROM AUTHOR]

Background: Imidazole propionate (IMP) is a histidine metabolite produced by some gut microorganisms in the human colon. Increased levels of IMP are associated with intestinal inflammation and the development and progression of cardiovascular disease and diabetes. However, the anti-inflammatory activity of IMP has not been investigated. This study aimed to elucidate the role of IMP in treating atopic dermatitis (AD). Methods: To understand how IMP mediates immunosuppression in AD, IMP was intraperitoneally injected into a Dermatophagoides farinae extract (DFE)/1-chloro-2,4 dinitrochlorobenzene (DNCB)-induced AD-like skin lesions mouse model. We also characterized the anti-inflammatory mechanism of IMP by inducing an AD response in keratinocytes through TNF-α/IFN-γ or IL-4 stimulation. Results: Contrary to the prevailing view that IMP is an unhealthy microbial metabolite, we found that IMP-treated AD-like skin lesions mice showed significant improvement in their clinical symptoms, including ear thickness, epidermal and dermal thickness, and IgE levels. Furthermore, IMP antagonized the expansion of myeloid (neutrophils, macrophages, eosinophils, and mast cells) and Th cells (Th1, Th2, and Th17) in mouse skin and prevented mitochondrial reactive oxygen species production by inhibiting mitochondrial energy production. Interestingly, we found that IMP inhibited AD by reducing glucose uptake in cells to suppress proinflammatory cytokines and chemokines in an AD-like in vitro model, sequentially downregulating the PI3K and mTORC2 signaling pathways centered on Akt, and upregulating DDIT4 and AMPK. Discussion: Our results suggest that IMP exerts anti-inflammatory effects through the metabolic reprogramming of skin inflammation, making it a promising therapeutic candidate for AD and related skin diseases. [ABSTRACT FROM AUTHOR]

Abstract Purpose Solid tumors such as lung adenocarcinoma include not only the tumor cells but also the microenvironment in which the tumor cells continuously interact with each other. An in-depth understanding of the oncological features and tumor microenvironment (TME) of lung adenocarcinoma and brain metastases at the single-cell level could provide new therapeutic strategies for brain metastases from lung adenocarcinoma. Methods To solve this problem, we performed single-cell RNA sequencing (scRNA-seq) analysis on 15 lung adenocarcinoma samples and 10 brain metastasis samples. Results A total of 86,282 single cells were obtained and divided into 8 cell types, including epithelial cells, endothelial cells, fibroblasts, oligodendrocytes, T/NK cells, B cells, mast cells, and macrophages. In brain metastases, we found a significantly lower proportion of T/NK cells and mast cells, and more severe immune dysregulation. In addition, we found a subpopulation of macrophages with high expression of metastasis-promoting-related genes enriched in brain metastatic tissues. Moreover, in brain metastases, we found a significantly increased proportion of myofibroblastic cancer-associated fibroblasts (myCAFs) and a higher angiogenic capacity of endothelial cells. Epithelial cells in brain metastases were more malignant and underwent genomic reprogramming. Next, we found that DNA damage-inducible transcript 4 (DDIT4) expression was upregulated in epithelial cells in brain metastases and was associated with poor prognosis. Finally, we experimentally validated that the downregulation of DDIT4 inhibited the proliferation, migration, and invasion of lung cancer cells. Conclusions This study depicts a single-cell atlas of lung adenocarcinoma and brain metastases by scRNA-seq and paves the way for the development of future therapeutic targets for brain metastases from lung cancer.

BackgroundImidazole propionate (IMP) is a histidine metabolite produced by some gut microorganisms in the human colon. Increased levels of IMP are associated with intestinal inflammation and the development and progression of cardiovascular disease and diabetes. However, the anti-inflammatory activity of IMP has not been investigated. This study aimed to elucidate the role of IMP in treating atopic dermatitis (AD). MethodsTo understand how IMP mediates immunosuppression in AD, IMP was intraperitoneally injected into a Dermatophagoides farinae extract (DFE)/1-chloro-2,4 dinitrochlorobenzene (DNCB)-induced AD-like skin lesions mouse model. We also characterized the anti-inflammatory mechanism of IMP by inducing an AD response in keratinocytes through TNF-α/IFN-γ or IL-4 stimulation. ResultsContrary to the prevailing view that IMP is an unhealthy microbial metabolite, we found that IMP-treated AD-like skin lesions mice showed significant improvement in their clinical symptoms, including ear thickness, epidermal and dermal thickness, and IgE levels. Furthermore, IMP antagonized the expansion of myeloid (neutrophils, macrophages, eosinophils, and mast cells) and Th cells (Th1, Th2, and Th17) in mouse skin and prevented mitochondrial reactive oxygen species production by inhibiting mitochondrial energy production. Interestingly, we found that IMP inhibited AD by reducing glucose uptake in cells to suppress proinflammatory cytokines and chemokines in an AD-like in vitro model, sequentially downregulating the PI3K and mTORC2 signaling pathways centered on Akt, and upregulating DDIT4 and AMPK. DiscussionOur results suggest that IMP exerts anti-inflammatory effects through the metabolic reprogramming of skin inflammation, making it a promising therapeutic candidate for AD and related skin diseases.

Repositioning of aspirin for a more effective breast cancer (BC) treatment requires identification of predictive biomarkers. However, the molecular mechanism underlying the anticancer activity of aspirin remains fully undefined. Cancer cells enhance de novo fatty acid (FA) synthesis and FA oxidation to maintain a malignant phenotype, and the mechanistic target of rapamycin (mTORC1) is required for lipogenesis. We, therefore, aimed to test if the expression of mTORC1 suppressor DNA damage-inducible transcript (DDIT4) affects the activity of main enzymes in FA metabolism after aspirin treatment. MCF-7 and MDA-MB-468 human BC cell lines were transfected with siRNA to downregulate DDIT4. The expression of carnitine palmitoyltransferase 1 A (CPT1A) and serine 79-phosphorylated acetyl-CoA carboxylase 1 (ACC1) were analyzed by Western Blotting. Aspirin enhanced ACC1 phosphorylation by two-fold in MCF-7 cells and had no effect in MDA-MB-468 cells. Aspirin did not change the expression of CPT1A in either cell line. We have recently reported DDIT4 itself to be upregulated by aspirin. DDIT4 knockdown resulted in 1.5-fold decreased ACC1 phosphorylation (dephosphorylation activates the enzyme), 2-fold increased CPT1A expression in MCF-7 cells, and 2.8-fold reduced phosphorylation of ACC1 following aspirin exposure in MDA-MB-468 cells. Thus, DDIT4 downregulation raised the activity of main lipid metabolism enzymes upon aspirin exposure which is an undesired effect as FA synthesis and oxidation are linked to malignant phenotype. This finding may be clinically relevant as DDIT4 expression has been shown to vary in breast tumors. Our findings justify further, more extensive investigation of the role of DDIT4 in aspirin’s effect on fatty acid metabolism in BC cells.

As one of the most important phthalates, di-isononyl phthalate (DINP) has been widely used as a common plasticizer in the food and personal care products sectors. In our previous study, we found that DINP can induce autophagy of ovarian granulosa cells; while the underlying mechanism is unclear. In the study, we showed that DINP exposure could induce autophagy of ovarian granulosa cells and KGN cells, accompanied with the increase in the mRNA and protein level of DDIT4. Furthermore, overexpression of DDIT4 were shown to induce autophagy of KGN cells; while knockdown of DDIT4 inhibited DINP-induced autophagy, implying that DDIT4 played an important role in DINP-induced autophagy of ovarian granulosa cells. There were three putative binding sites of transcription factor ATF4 in the promoter region of DDIT4 gene, suggesting that DDIT4 might be regulated by ATF4. Herein, we found that overexpression of ATF4 could upregulate the expression of DDIT4 in KGN cells, while knockdown of ATF4 inhibited its expression. Subsequently, ATF4 was identified to bind to the promoter region of DDIT4 gene and promote its transcription. The expression of ATF4 was also increased in the DINP-exposed granulosa cells, and ATF4 overexpression promoted autophagy of KGN cells; whereas knockdown of ATF4 alleviated DINP-induced upregulation of DDIT4 and autophagy of the cells. Taken together, DINP triggered autophagy of ovarian granulosa cells through activating ATF4/DDIT4 signals.

Chronic myeloid leukemia (CML) is a hematopoietic malignancy driven by the fusion gene BCR :: ABL1. Drug resistance to tyrosine kinase inhibitors (TKIs), due to BCR::ABL1 mutations and residual leukemia stem cells (LSCs), remains a major challenge in CML treatment. Here, we revealed the requirement of the vitamin D receptor (VDR) in the progression of CML. VDR was upregulated by BCR::ABL1 and highly expressed in CML cells. Interestingly, VDR knockdown inhibited the proliferation of CML cells driven by both BCR::ABL1 and TKI-resistant BCR::ABL1 mutations. Mechanistically, VDR transcriptionally regulated DDIT4 expression; reduced DDIT4 levels upon VDR knockdown triggered DNA damage and senescence via p53 signaling activation in CML cells. Furthermore, VDR deficiency not only suppressed tumor burden and progression in primary CML mice but also reduced the self-renewal capacity of CML-LSCs. Together, our study demonstrated that targeting VDR is a promising strategy to overcome TKI resistance and eradicate LSCs in CML. [ABSTRACT FROM AUTHOR]

Glioblastoma multiforme (GBM) is the most common and aggressive brain tumor with a poor prognosis. The growth of GBM cells depends on the core transcriptional apparatus, thus rendering RNA polymerase (RNA pol) complex as a candidate therapeutic target. The RNA pol II subunit B (POLR2B) gene encodes the second largest subunit of the RNA pol II (RPB2); however, its genomic status and function in GBM remain unclear. Certain GBM data sets in cBioPortal were used for investigating the genomic status and expression of POLR2B in GBM. The function of RPB2 was analyzed following knockdown of POLR2B expression by shRNA in GBM cells. The cell counting kit-8 assay and PI staining were used for cell proliferation and cell cycle analysis. A xenograft mouse model was established to analyze the function of RPB2 in vivo. RNA sequencing was performed to analyze the RPB2-regulated genes. GO and GSEA analyses were applied to investigate the RPB2-regulated gene function and associated pathways. In the present study, the genomic alteration and overexpression of the POLR2B gene was described in glioblastoma. The data indicated that knockdown of POLR2B expression suppressed tumor cell growth of glioblastoma in vitro and in vivo. The analysis further demonstrated the identification of the RPB2-regulated gene sets and highlighted the DNA damage-inducible transcript 4 gene as the downstream target of the POLR2B gene. The present study provides evidence indicating that RPB2 functions as a growth regulator in glioblastoma and could be used as a potential therapeutic target for the treatment of this disease. • POLR2B gene is rarely mutated but amplified in a subset of glioblastoma patients which results in the overexpression of RPB2. • Knockdown of POLR2B gene inhibit cell proliferation and cell cycle progression in glioblastoma cell lines. • DNA damage-inducible transcript 4 gene (DDIT4) was found to be a downstream target of POLR2B gene. [ABSTRACT FROM AUTHOR]

Purpose: Solid tumors such as lung adenocarcinoma include not only the tumor cells but also the microenvironment in which the tumor cells continuously interact with each other. An in-depth understanding of the oncological features and tumor microenvironment (TME) of lung adenocarcinoma and brain metastases at the single-cell level could provide new therapeutic strategies for brain metastases from lung adenocarcinoma. Methods: To solve this problem, we performed single-cell RNA sequencing (scRNA-seq) analysis on 15 lung adenocarcinoma samples and 10 brain metastasis samples. Results: A total of 86,282 single cells were obtained and divided into 8 cell types, including epithelial cells, endothelial cells, fibroblasts, oligodendrocytes, T/NK cells, B cells, mast cells, and macrophages. In brain metastases, we found a significantly lower proportion of T/NK cells and mast cells, and more severe immune dysregulation. In addition, we found a subpopulation of macrophages with high expression of metastasis-promoting-related genes enriched in brain metastatic tissues. Moreover, in brain metastases, we found a significantly increased proportion of myofibroblastic cancer-associated fibroblasts (myCAFs) and a higher angiogenic capacity of endothelial cells. Epithelial cells in brain metastases were more malignant and underwent genomic reprogramming. Next, we found that DNA damage-inducible transcript 4 (DDIT4) expression was upregulated in epithelial cells in brain metastases and was associated with poor prognosis. Finally, we experimentally validated that the downregulation of DDIT4 inhibited the proliferation, migration, and invasion of lung cancer cells. Conclusions: This study depicts a single-cell atlas of lung adenocarcinoma and brain metastases by scRNA-seq and paves the way for the development of future therapeutic targets for brain metastases from lung cancer. [ABSTRACT FROM AUTHOR]

This study was aimed to identify a novel metastasis-promoting molecule and elucidate its functional and prognostic roles in cervical cancer. DDIT4 (DNA-damage-inducible transcript 4), a hypoxia-inducible gene, was identified by analyzing multiple microarray databases. The correlation between DDIT4 expression in immunohistochemistry and clinicopathological characteristics in the public database and our cohort was evaluated by statistical analysis. Transwell® assay and wound-healing assay to determine cell migration and invasion were performed. DDIT4 was knocked down using siRNA or lentiviral vectors. The potential downstream pathways of DDIT4 were explored and verified by a gene set enrichment analysis and western blotting. The in vivo metastatic capability was determined with the use of an intraperitoneal injection mouse model. In the analysis of the public database and our cohort, DDIT4 high expression was significantly related to short overall survival and lymph node metastasis in patients with early-stage cervical cancer. The knockdown of DDIT4 attenuated the migration and invasion activity of tumor cells in vitro and reduced the expression of epithelial–mesenchymal transition (EMT)-related proteins and the NF-κB pathway in cervical cancer cells. DDIT4 also promoted tumor progression in the mouse model. Our results indicate that DDIT4 can be a prognostic indicator in cervical cancer and promote lymph node metastasis, augmenting malignancy via the EMT and NF-kB pathways. [ABSTRACT FROM AUTHOR]

Background: Substantial studies have demonstrated that oxidative stress placenta and endothelial injury are considered to inextricably critical events in the pathogenesis of preeclampsia (PE). Systemic inflammatory response and endothelial dysfunction are induced by the circulating factors released from oxidative stress placentae. As a novel biomarker of oxidative stress, advanced oxidation protein products (AOPPs) levels are strongly correlated with PE characteristics. Nevertheless, the molecular mechanism underlying the effect of factors is still largely unknown. Methods: With the exponential knowledge on the importance of placenta-derived extracellular vesicles (pEVs), we carried out lncRNA transcriptome profiling on small EVs (sEVs) secreted from AOPPs-treated trophoblast cells and identified upregulated lncRNA TDRKH-AS1 as a potentially causative factor for PE. We isolated and characterized sEVs from plasma and trophoblast cells by transmission electron microscopy (TEM), nanoparticle tracking analysis (NTA) and western blotting. The expression and correlation of lncRNA TDRKH-AS1 were evaluated using qRT-PCR in plasmatic sEVs and placentae from patients. Pregnant mice injected with TDRKH-AS1-riched trophoblast sEVs was performed to detect the TDRKH-AS1 function in vivo. To investigate the potential effect of sEVs-derived TDRKH-AS1 on endothelial function in vitro, transcriptome sequencing, scanning electron Microscopy (SEM), immunofluorescence, ELISA and western blotting were conducted in HUVECs. RNA pulldown, mass spectrometry, RNA immunoprecipitation (RIP), chromatin isolation by RNA purification (ChIRP) and coimmunoprecipitation (Co-IP) were used to reveal the latent mechanism of TDRKH-AS1 on endothelial injury. Results: The expression level of TDRKH-AS1 was significantly increased in plasmatic sEVs and placentae from patients, and elevated TDRKH-AS1 in plasmatic sEVs was positively correlated with clinical severity of the patients. Moreover, pregnant mice injected with TDRKH-AS1-riched trophoblast sEVs exhibited a hallmark feature of PE with increased blood pressure and systemic inflammatory responses. Pyroptosis, an inflammatory form of programmed cell death, is involved in the development of PE. Indeed, our in vitro study indicated that sEVs-derived TDRKH-AS1 secreted from AOPPs-induced trophoblast elevated DDIT4 expression levels to trigger inflammatory response of pyroptosis in endothelial cells through interacting with PDIA4. Conclusions: Herein, results in the present study supported that TDRKH-AS1 in sEVs isolated from oxidative stress trophoblast may be implicated in the pathogenesis of PE via inducing pyroptosis and aggravating endothelial dysfunction. [ABSTRACT FROM AUTHOR]

Tris (1,3-dichloro-2-propyl) phosphate (TDCIPP) is a commonly used organophosphate-based flame retardant and can bio-accumulate in human tissues and organs. As its structure is similar to that of neurotoxic organophosphate pesticides, the neurotoxicity of TDCIPP has raised widespread concerns. TDCIPP can increase neuronal apoptosis and induce autophagy. However, its regulatory mechanism remains unclear. In this study, we found that the expression upregulation of the DNA Damage-Inducible Transcript 4 (DDIT4) protein, which might play essential roles in TDCIPP-induced neuronal autophagy and apoptosis, was observed in TDCIPP-treated differentiated rat PC12 cells. Furthermore, we determined the protective effect of the DDIT4 suppression on the autophagy and apoptosis induced by TDCIPP using Western blot (WB) and Flow cytometry (FACS) analysis. We observed that TDCIPP treatment increased the DDIT4, the autophagy marker Beclin-1, and the microtubule-associated protein light chain 3-II (LC3II) expressions and decreased the mTOR phosphorylation levels. Conversely, the suppression of DDIT4 expression increased the p-mTOR expression and decreased cell autophagy and apoptosis. Collectively, our results revealed the function of DDIT4 in cell death mechanisms triggered by TDCIPP through the mTOR signaling axis in differentiated PC12 cells. Thus, this study provided vital evidence necessary to explain the mechanism of TDCIPP-induced neurotoxicity in differentiated PC12 cells. [Display omitted] [ABSTRACT FROM AUTHOR]

BACKGROUND: Despite extensive research on endometrial cancer and tumor hypoxic microenvironment, there are no reports exploring the role of DDIT4 in endometrial cancer. OBJECTIVE: This study aimed to elucidate the significance of DDIT4, as a prognostic biomarker for endometrial cancer by immunohistochemical staining and statistical analysis. METHODS: Four endometrial cancer cells were cultured under normoxia and hypoxia, and the differentially expressed genes were examined using RNA-seq. Immunohistochemical staining for DDIT4 and HIF1A was performed in 86 patients with type II endometrial cancer treated at our hospital, and their correlation with other clinicopathological factors and the prognostic role was analyzed using statistical methods. RESULTS: The expression analysis of hypoxia-inducible genes using four types of endometrial cancer cells revealed that DDIT4 was among the 28 genes that were upregulated in all cells. Based on our results of immunohistochemistry of DDIT4 expression in endometrial cancer tissues, univariate and multivariate analyses based on COX regression analysis showed that high DDIT4 expression significantly correlated to favorable prognosis in both progression-free survival and overall survival. Limited to recurrent cases, metastasis to only lymph nodes was significantly related to high DDIT4 expression, whereas metastasis to other parenchymal organs was significantly dominant in patients with low DDIT4 expression. CONCLUSIONS: The expression of DDIT4 enables to predict survival and recurrence in type II endometrial cancer. [ABSTRACT FROM AUTHOR]

Objective: screening of previously selected DDIT4 inhibitors by their ability to suppress basal and glucocorticoid-induced expression of this gene in breast cancer (BC) cells, as well as evaluation of antiproliferative and cytotoxic effects of the studied drug combinations the antiproliferative and proapoptotic effects of studied drug combinations. Material and Methods. Breast cancer cells of the luminal, HER2- positive and triple negative subtypes were used. The effects of drugs (rapamycin, wortmannin, LY-294002, apigenin, resveratrol, curcumin, CGP-60474, and emetine) on the basal and glucocorticoid-induced levels of expression of the DDIT4 gene and its protein product were evaluated by qPCR and Western blotting assays. Results. Emetine, rapamycin, wortmannin, LY-294002 and CGP-60474 demonstrated DDIT4-inhibition activity. Glucocorticoid dexamethasone showed cytotoxic effects and antiproliferative activity in combination with emetine, CGP-60474 (C protein kinase inhibitor), resveratrol and curcumin. Conclusion. Novel inhibitors of DDIT4 in breast cancer model cells in vitro were found. Emetine and CGP-60474 are the most promising drugs for further research.

The adaptive response to hypoxia involves the transcriptional induction of three transcription factors called hypoxia inducible factor alpha 1, 2 and 3 (HIF-1α, HIF-2α, and HIF-3α) which dimerize with constitutively expressed beta chains that together form the HIF-1, -2 and -3 transcription factors. During normoxic conditions, the alpha chain is expressed at low levels since its stability is regulated by prolyl-hydroxylation that promotes subsequent ubiquitination and degradation. During hypoxic conditions, however, the prolyl hydroxylases are less active, and the alpha chain accumulates through elevated protein stability and the elevated induction of expression. Two of the three HIFs isoforms present in mammals, HIF-1 and HIF-2, are well characterized and have overlapping functions that promote cell survival, whereas HIF-3’s role remains less clear. The HIF-3 response is complicated because the HIF3A gene can utilize different promotors and alternate splicing sites that result in a number of different HIF-3α isoforms. Here, using human umbilical vein endothelial cells (HUVECs), we demonstrate that one of the isoforms of HIF-3α, isoform 2 (HIF-3α2) accumulates at a late stage of hypoxia and induces the expression of DNA damage inducible transcript 3 (DDIT4), a gene known to promote apoptosis. We also demonstrate that caspase 3/7 activity is elevated, supporting that the role of the HIF-3α2 isoform is to promote apoptosis. Furthermore, we provide evidence that HIF-3α2 is also expressed in seven other primary endothelial cell types, suggesting that this may be a common feature of HIF-3α2 in endothelial cells.

Autism spectrum disorder (ASD) is a complex disease with unclear etiology. Studies have shown that ferroptosis is also related to ASD progression, but the specific mechanism is still unclear. Valproic acid (VPA) induced neuronal ferroptosis in vitro. Mechanistic studies showed that both VPA and ferroptosis inducers promoted the expression of DDIT4 in neurons, thereby inhibiting the activation of the PI3K/Akt pathway. DDIT4 increased the accumulation of ROS, MDA and Fe2+, inhibited neuronal viability and downregulated GPX4 expression by inactivating the PI3K/Akt pathway. Ferroptosis inhibitors reversed the anti-survival effect of DDIT4, indicating that DDIT4 enhances ferroptosis through the PI3K/Akt pathway, thereby inhibiting neuronal viability. Further in vivo experiments found that autistic mice had high levels of ROS, MDA and Fe2+, increased DDIT4 expression, and downregulated expression levels of GPX4, p-PI3K and p-Akt; after downregulation of DDIT4 expression, the accumulation of ROS, MDA and Fe2+ was significantly reduced, while the expression levels of GPX4, p-PI3K and p-Akt were upregulated, indicating that DDIT4 knockdown reduces ferroptosis in autistic mice. In addition, DDIT4 downregulation, PI3K/Akt pathway activation, and ferroptosis inhibitors all improved social behavior deficits, repetitive stereotyped and compulsive behaviors, anxiety and exploratory behaviors in autistic mice, but PI3K/Akt pathway inhibitors significantly blocked the rescue of abnormal behaviors by DDIT4 downregulation in autistic mice. Therefore, downregulation of DDIT4 expression ameliorates abnormal behaviors in autism by inhibiting ferroptosis via the PI3K/Akt pathway, indicating that DDIT4, the PI3K/Akt pathway and ferroptosis have key roles in autism. • VPA induces DDIT4 expression to promote neuronal ferroptosis. • VPA promotes neuronal ferroptosis through the DDIT4/PI3K/Akt pathway. • Downregulation of DDIT4 expression activates the PI3K/Akt pathway to alleviate ferroptosis in autistic mice. • The DDIT4/PI3K/Akt pathway regulates ferroptosis to affect abnormal behaviors in autistic mice. [ABSTRACT FROM AUTHOR]

Endoplasmic reticulum (ER) stress and inflammation are hallmarks of myocardial impairment. Here, we investigated the role of the stress response protein regulated in development and DNA damage 1 (REDD1) as a molecular link between ER stress and inflammation in cardiomyocytes. In mice fed a high-fat high-sucrose (HFHS, 42% kcal fat, 34% sucrose by weight) diet for 12 wk, REDD1 expression in the heart was increased in coordination with markers of ER stress and inflammation. In human AC16 cardiomyocytes exposed to either hyperglycemic conditions or the saturated fatty acid palmitate, REDD1 expression was increased coincident with ER stress and upregulated expression of the proinflammatory cytokines IL-1Β, IL-6, and TNFɑ. In cardiomyocytes exposed to hyperglycemic/hyperlipidemic conditions, pharmacological inhibition of the ER kinase protein kinase RNA-like endoplasmic reticulum kinase (PERK) or knockdown of the transcription factor ATF4 prevented the increase in REDD1 expression. REDD1 deletion reduced proinflammatory cytokine expression in both cardiomyocytes exposed to hyperglycemic/hyperlipidemic conditions and in the hearts of obese mice. Overall, the findings support a model wherein HFHS diet contributes to the development of inflammation in cardiomyocytes by promoting REDD1 expression via activation of a PERK/ATF4 signaling axis. [ABSTRACT FROM AUTHOR]

Introduction: Dysbiosis of the lower airway flora is associated with lung cancer, of which the relationship between Streptococcus, especially pathogenic Streptococcus pneumoniae (S. pneumoniae), and the progression of lung cancer are unclear. Methods: Bronchoalveolar lavage fluid (BALF) samples were prospectively collected from patients with pulmonary nodules during diagnostic bronchoscopy, and finally included 70 patients diagnosed with primary lung cancer and 20 patients with benign pulmonary nodules as the disease control group. The differential flora was screened by 16S ribosomal RNA (rRNA) gene amplicon sequencing. An in vitro infection model of lung adenocarcinoma (LUAD) cells exposed to S.pneumoniae was established to observe its effects on cell migration and invasion ability. Exploring the molecular mechanisms downstream of DDIT4 through its loss- and gain-of-function experiments. Results: 16S rRNA sequencing analysis showed that the abundance of Streptococcus in the lower airway flora of lung cancer patients was significantly increased. After exposure to S. pneumoniae, A549 and H1299 cells significantly enhanced their cell migration and invasion ability. The results of DDIT4 loss- and gain-of-function experiments in A549 cells suggest that up-regulation of DDIT4 activates the mTORC2/Akt signaling pathway, thereby enhancing the migration and invasion of A549 cells while not affecting mTORC1. Immunofluorescence (IF) and fluorescence in situ hybridization (FISH) showed that S. pneumoniae was enriched in LUAD tissues, and DDIT4 expression was significantly higher in cancer tissues than in non-cancerous tissues. The increased expression of DDIT4 was also related to the poor prognosis of patients with LUAD. Discussion: The data provided by this study show that S. pneumoniae enriched in the lower airway of patients with lung cancer can up-regulate DDIT4 expression and subsequently activate the mTORC2/AKT signal pathway, thereby increasing the migration and invasion abilities of A549 cells. Our study provides a potential new mechanism for targeted therapy of LUAD. [ABSTRACT FROM AUTHOR]

Objective: Knee osteoarthritis (KOA) is characterized by structural changes. Aging is a major risk factor for KOA. Therefore, the objective of this study was to examine the role of genes related to aging and circadian rhythms in KOA., Methods: This study identified differentially expressed genes (DEGs) by comparing gene expression levels between normal and KOA samples from the GEO database. Subsequently, we intersected the DEGs with aging-related circadian rhythm genes to obtain a set of aging-associated circadian rhythm genes differentially expressed in KOA. Next, we conducted Mendelian randomization (MR) analysis, using the differentially expressed aging-related circadian rhythm genes in KOA as the exposure factors, their SNPs as instrumental variables, and KOA as the outcome event, to explore the causal relationship between these genes and KOA. We then performed Gene Set Enrichment Analysis (GSEA) to investigate the pathways associated with the selected biomarkers, conducted immune infiltration analysis, built a competing endogenous RNA (ceRNA) network, and performed molecular docking studies. Additionally, the findings and functional roles of the biomarkers were further validated through experiments on human cartilage tissue and cell models., Results: A total of 75 differentially expressed aging-circadian rhythm related genes between the normal group and the KOA group were identified by difference analysis, primarily enriched in the circadian rhythm pathway. Two biomarkers (PFKFB4 and DDIT4) were screened by MR analysis. Then, immune infiltration analysis showed significant differences in three types of immune cells (resting dendritic cells, resting mast cells, and M2 macrophages), between the normal and KOA groups. Drug prediction and molecular docking results indicated stable binding of PFKFB4 to estradiol and bisphenol_A, while DDIT4 binds stably to nortriptyline and trimipramine. Finally, cell lines with stable expression of the biomarkers were established by lentiviral infection and resistance screening, Gene expression was significantly elevated in overexpressing cells of PFKFB4 and DDIT4 and reversed the proliferation and migration ability of cells after IL-1β treatment., Conclusions: Two diagnostic and therapeutic biomarkers associated with aging-circadian rhythm in KOA were identified. Functional analysis, molecular mechanism exploration, and experimental validation further elucidated their roles in KOA, offering novel perspectives for the prevention and treatment of the disease., (© 2025 The Author(s). Orthopaedic Surgery published by Tianjin Hospital and John Wiley & Sons Australia, Ltd.)

According to mounting evidence, long noncoding RNAs (lncRNAs) play a vital role in regulated cell death (RCD). A potential strategy for cancer therapy involves triggering ferroptosis, a novel form of RCD. Although it is thought to be an autophagy-dependent process, it is still unclear how the two processes interact. This study characterized a long intergenic noncoding RNA, LINC00551, expressed at a low level in lung adenocarcinoma (LUAD) and some other cancers. Overexpression of LINC00551 suppresses cell viability while promoting autophagy and RSL-3-induced ferroptosis in LUAD cells. LINC00551 acts as a competing endogenous RNA (ceRNA) and binds with miR-4328 which up-regulates the target DNA damage-inducible transcript 4 (DDIT4). DDIT4 inhibits the activity of mTOR, promotes LUAD autophagy, and then promotes the ferroptosis of LUAD cells in an autophagy-dependent manner. This study provided an insight into the molecular mechanism regulating ferroptosis and highlighted LINC00551 as a potential therapeutic target for LUAD. [ABSTRACT FROM AUTHOR]

Abstract Background Various diagnostic and prognostic tools exist in colorectal cancer (CRC) due to multiple genetic and epigenetic alterations causing the disease. Today, the expression of RNAs is being used as prognostic markers for cancer. Methods In the current study, various dysregulated RNAs in CRC were identified via bioinformatics prediction. Expression of several of these RNAs were measured by RT-qPCR in 48 tissues from CRC patients as well as in colorectal cancer stem cell-enriched spheroids derived from the HT-29 cell line. The relationships between the expression levels of these RNAs and clinicopathological features were analyzed. Results Our bioinformatics analysis determined 11 key mRNAs, 9 hub miRNAs, and 18 lncRNAs which among them 2 coding RNA genes including DDIT4 and SULF1 as well as 3 non-coding RNA genes including TPTEP1, miR-181d-5p, and miR-148b-3p were selected for the further investigations. Expression of DDIT4, TPTEP1, and miR-181d-5p showed significantly increased levels while SULF1 and miR-148b-3p showed decreased levels in CRC tissues compared to the adjacent normal tissues. Positive relationships between DDIT4, SULF1, and TPTEP1 expression and metastasis and advanced stages of CRC were observed. Additionally, our results showed significant correlations between expression of TPTEP1 with DDIT4 and SULF1. Conclusions Our findings demonstrated increased expression levels of DDIT4 and TPTEP1 in CRC were associated with more aggressive tumor behavior and more advanced stages of the disease. The positive correlations between TPTEP1 as non-coding RNA and both DDIT4 and SULF1 suggest a regulatory effect of TPTEP1 on these genes.

DNA damage-inducible transcript 4 (DDIT4) is a ubiquitous protein whose expression is transiently increased in response to various stressors. Chronic expression has been linked to various pathologies, including neurodegeneration, inflammation, and cancer. DDIT4 is best recognized for repressing mTORC1, an essential protein complex activated by nutrients and hormones. Accordingly, DDIT4 regulates metabolism, oxidative stress, hypoxic survival, and apoptosis. Despite these well-defined biological functions, little is known about its interacting partners and their unique molecular functions. Here, fusing an enhanced ascorbate peroxidase 2 (APEX2) biotin-labeling enzyme to DDIT4 combined with mass spectrometry, the proteins in the immediate vicinity of DDIT4 in either unstressed or acute stress conditions were identified in situ. The context-dependent interacting proteomes were quantitatively but not functionally distinct. DDIT4 had twice the number of interaction partners during acute stress compared to unstressed conditions, and while the two protein lists had minimal overlap in terms of identity, the proteins' molecular function and classification were essentially identical. Moonlighting keratins and ribosomal proteins dominated the proteomes in both unstressed and stressed conditions, with many of their members having established non-canonical and indispensable roles during stress. Multiple keratins regulate mTORC1 signaling via the recruitment of 14-3-3 proteins, whereas ribosomal proteins control translation, cell cycle progression, DNA repair, and death by sequestering critical proteins. In summary, two potentially distinct mechanisms of DDIT4 molecular function have been identified, paving the way for additional research to confirm and consolidate these findings. [ABSTRACT FROM AUTHOR]

A recent epigenome-wide association study of genes associated with type 2 diabetics (T2D), used integrative cross-omics analysis to identify 22 abnormally methylated CpG sites associated with insulin and glucose metabolism. Here, in this epigenetic analysis we preliminarily determine whether the same CpG sites identified in T2D also apply to type 1 diabetes (T1D). We then determine whether BCG vaccination could correct the abnormal methylation patterns, considering that the two diseases share metabolic derangements. T1D (n = 13) and control (n = 8) subjects were studied at baseline and then T1D subjects studied yearly for 3 years after receiving BCG vaccinations in a clinical trial. In this biomarker analysis, methylation patterns were evaluated on CD4+ T-lymphocytes from baseline and yearly blood samples using the human Illumina Methylation EPIC Bead Chip. Methylation analysis combined with mRNA analysis using RNAseq. Broad but not complete overlap was observed between T1D and T2D in CpG sites with abnormal methylation. And in the three-year observation period after BCG vaccinations, the majority of the abnormal methylation sites were corrected in vivo. Genes of particular interest were related to oxidative phosphorylation (CPT1A, LETM1, ABCG1), to the histone lysine demethylase gene (KDM2B), and mTOR signaling through the DDIT4 gene. The highlighted CpG sites for both KDM2B and DDIT4 genes were hypomethylated at baseline compared to controls; BCG vaccination corrected the defect by hypermethylation. Glycolysis is regulated by methylation of genes. This study unexpectedly identified both KDM2B and DDIT4 as genes controlling BCG-driven re-methylation of histones, and the activation of the mTOR pathway for facilitated glucose transport respectively. The BCG effect at the gene level was confirmed by reciprocal mRNA changes. The DDIT4 gene with known inhibitory role of mTOR was re-methylated after BCG, a step likely to allow improved glucose transport. BCGs driven methylation of KDM2B 's site should halt augmented histone activity, a step known to allow cytokine activation and increased glycolysis. [ABSTRACT FROM AUTHOR]

Our previous studies have shown that meningitic Escherichia coli can colonize the brain and cause neuroinflammation. Controlling the balance of inflammatory responses in the host central nervous system is particularly vital. Emerging evidence has shown the important regulatory roles of long non-coding RNAs (lncRNAs) in a wide range of biological and pathological processes. However, whether lncRNAs participate in the regulation of meningitic E. coli-mediated neuroinflammation remains unknown. In the present study, we characterized a cytoplasm-enriched antisense lncRNA DDIT4-AS1, which showed similar concordant expression patterns with its parental mRNA DDIT4 upon E. coli infection. DDIT4-AS1 modulated DDIT4 expression at both mRNA and protein levels. Mechanistically, DDIT4-AS1 promoted the stability of DDIT4 mRNA through RNA duplex formation. DDIT4-AS1 knockdown and DDIT4 knockout both attenuated E. coli-induced NF-κB signaling as well as pro-inflammatory cytokines expression, and DDIT4-AS1 regulated the inflammatory response by targeting DDIT4. In summary, our results show that DDIT4-AS1 promotes E. coli-induced neuroinflammatory responses by enhancing the stability of DDIT4 mRNA through RNA duplex formation, providing potential nucleic acid targets for new therapeutic interventions in the treatment of bacterial meningitis. [ABSTRACT FROM AUTHOR]

The tumor microenvironment (TME) plays an important regulatory role in the progression of non-small cell lung cancer (NSCLC). Mesenchymal stem cells (MSCs) in the TME might contribute to the occurrence and development of cancer. This study evaluates the role of differentially expressed genes (DEGs) of MSCs and the development of NSCLC and develops a prognostic risk model to assess the therapeutic responses. The DEGs in MSCs from lung tissues and from normal tissues were analyzed using GEO2R. The functions and mechanisms of the DEGs were analyzed using the Gene ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG). Additionally, the Cancer Genome Atlas (TCGA) database was used to determine the expression levels of the DEGs of MSCs in the NSCLC tissues. The prognostic factors of NSCLC related to MSCs were screened by survival analysis, meta-analysis, Cox regression analysis, and a prognostic risk model and nomogram was developed. The signaling mechanisms and immune roles that risk model participate in NSCLC development were determined via Gene Set Enrichment Analysis and CIBERSORT analysis. Compared to the normal tissues, 161 DEGs were identified in the MSCs of the lung tissues. These DEGs were associated with mechanisms, such as DNA replication, nuclear division, and homologous recombination. The overexpression of DDIT4 , IL6 , ITGA11 , MME , MSX2 , POSTN , and TRPA1 were associated with dismal prognosis of NSCLC patients. A high-risk score based on the prognostic risk model indicated the dismal prognosis of NSCLC patients. The nomogram showed that the age, clinical stage, and risk score affected the prognosis of NSCLC patients. Further, the high-risk model was associated with signaling mechanisms, such as the ECM-receptor interaction pathways, cytokine-cytokine receptor interaction, and MAPK pathways, involved in the progression of NSCLC and was also related to the components of the immune system, such as macrophages M0, T follicular helper cells, regulatory T cells. Therefore, the risk model and nomogram that was constructed on the basis of MSC-related factors such as POSTN , TRPA1 , and DDIT4 could facilitate the discovery of target molecules that participate in the progression of NSCLC, which might also serve as new candidate markers for evaluating the prognosis of NSCLC patients. [ABSTRACT FROM AUTHOR]

Abstract Background Emerging studies have disclosed long non-coding RNAs (lncRNAs) as pivotal modulators in the progression of prostate cancer (PCa). Current research planned to figure out the involvement of lncRNA nicotinamide nucleotide transhydrogenase antisense RNA 1 (NNT-AS1) in PCa. Methods RNA expression was examined using RT-qPCR in PCa cells. Functional assays assessed the viability, proliferation, apoptosis and migration of PCa cells. RNA pull down and luciferase reporter experiments detected the interplay between miRNA and lncRNA or mRNA. Results NNT-AS1 was apparently upregulated in PCa cells. NNT-AS1 deficiency abrogated PCa cell viability, proliferation and migration but promoted apoptosis. Besides, miR-496 could be sequestered by NNT-AS1 to elevate the expression of DNA damage inducible transcript 4 (DDIT4) in PCa. Rescue assays indicated that overexpressed DDIT4 or restrained miR-496 could reverse the influence of NNT-AS1 depletion on malignant processes in PCa cells. Conclusion NNT-AS1 contributes to the malignant phenotypes of PCa cells through targeting miR-496 to boost DDIT4 expression.

The tumor microenvironment (TME) plays an important regulatory role in the progression of non-small cell lung cancer (NSCLC). Mesenchymal stem cells (MSCs) in the TME might contribute to the occurrence and development of cancer. This study evaluates the role of differentially expressed genes (DEGs) of MSCs and the development of NSCLC and develops a prognostic risk model to assess the therapeutic responses. The DEGs in MSCs from lung tissues and from normal tissues were analyzed using GEO2R. The functions and mechanisms of the DEGs were analyzed using the Gene ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG). Additionally, the Cancer Genome Atlas (TCGA) database was used to determine the expression levels of the DEGs of MSCs in the NSCLC tissues. The prognostic factors of NSCLC related to MSCs were screened by survival analysis, meta-analysis, Cox regression analysis, and a prognostic risk model and nomogram was developed. The signaling mechanisms and immune roles that risk model participate in NSCLC development were determined via Gene Set Enrichment Analysis and CIBERSORT analysis. Compared to the normal tissues, 161 DEGs were identified in the MSCs of the lung tissues. These DEGs were associated with mechanisms, such as DNA replication, nuclear division, and homologous recombination. The overexpression of DDIT4, IL6, ITGA11, MME, MSX2, POSTN, and TRPA1 were associated with dismal prognosis of NSCLC patients. A high-risk score based on the prognostic risk model indicated the dismal prognosis of NSCLC patients. The nomogram showed that the age, clinical stage, and risk score affected the prognosis of NSCLC patients. Further, the high-risk model was associated with signaling mechanisms, such as the ECM-receptor interaction pathways, cytokine-cytokine receptor interaction, and MAPK pathways, involved in the progression of NSCLC and was also related to the components of the immune system, such as macrophages M0, T follicular helper cells, regulatory T cells. Therefore, the risk model and nomogram that was constructed on the basis of MSC-related factors such as POSTN, TRPA1, and DDIT4 could facilitate the discovery of target molecules that participate in the progression of NSCLC, which might also serve as new candidate markers for evaluating the prognosis of NSCLC patients.

ABSTRACT The relationship between the active form of vitamin D3 (1,25‐dihydroxyvitamin D, 1,25(OH)2D) and reactive oxygen species (ROS), two integral signaling molecules of the cell, is poorly understood. This is striking, given that both factors are involved in cancer cell regulation and metabolism. Mitochondria (mt) dysfunction is one of the main drivers of cancer, producing more mitochondria, higher cellular energy, and ROS that can enhance oxidative stress and stress tolerance responses. To study the effects of 1,25(OH)2D on metabolic and mt dysfunction, we used the vitamin D receptor (VDR)‐sensitive MG‐63 osteosarcoma cell model. Using biochemical approaches, 1,25(OH)2D decreased mt ROS levels, membrane potential (ΔΨmt), biogenesis, and translation, while enforcing endoplasmic reticulum/mitohormetic stress adaptive responses. Using a mitochondria‐focused transcriptomic approach, gene set enrichment and pathway analyses show that 1,25(OH)2D lowered mt fusion/fission and oxidative phosphorylation (OXPHOS). By contrast, mitophagy, ROS defense, and epigenetic gene regulation were enhanced after 1,25(OH)2D treatment, as well as key metabolic enzymes that regulate fluxes of substrates for cellular architecture and a shift toward non‐oxidative energy metabolism. ATACseq revealed putative oxi‐sensitive and tumor‐suppressing transcription factors that may regulate important mt functional genes such as the mTORC1 inhibitor, DDIT4/REDD1. DDIT4/REDD1 was predominantly localized to the outer mt membrane in untreated MG‐63 cells yet sequestered in the cytoplasm after 1,25(OH)2D and rotenone treatments, suggesting a level of control by membrane depolarization to facilitate its cytoplasmic mTORC1 inhibitory function. The results show that 1,25(OH)2D activates distinct adaptive metabolic responses involving mitochondria to regain redox balance and control the growth of osteosarcoma cells. © 2021 The Authors. JBMR Plus published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research.

The adaptive response to hypoxia involves the transcriptional induction of three transcription factors called hypoxia inducible factor alpha 1, 2 and 3 (HIF-1α, HIF-2α, and HIF-3α) which dimerize with constitutively expressed beta chains that together form the HIF-1, -2 and -3 transcription factors. During normoxic conditions, the alpha chain is expressed at low levels since its stability is regulated by prolyl-hydroxylation that promotes subsequent ubiquitination and degradation. During hypoxic conditions, however, the prolyl hydroxylases are less active, and the alpha chain accumulates through elevated protein stability and the elevated induction of expression. Two of the three HIFs isoforms present in mammals, HIF-1 and HIF-2, are well characterized and have overlapping functions that promote cell survival, whereas HIF-3's role remains less clear. The HIF-3 response is complicated because the HIF3A gene can utilize different promotors and alternate splicing sites that result in a number of different HIF-3α isoforms. Here, using human umbilical vein endothelial cells (HUVECs), we demonstrate that one of the isoforms of HIF-3α, isoform 2 (HIF-3α2) accumulates at a late stage of hypoxia and induces the expression of DNA damage inducible transcript 3 (DDIT4), a gene known to promote apoptosis. We also demonstrate that caspase 3/7 activity is elevated, supporting that the role of the HIF-3α2 isoform is to promote apoptosis. Furthermore, we provide evidence that HIF-3α2 is also expressed in seven other primary endothelial cell types, suggesting that this may be a common feature of HIF-3α2 in endothelial cells. [ABSTRACT FROM AUTHOR]

The relationship between the active form of vitamin D3 (1,25‐dihydroxyvitamin D, 1,25(OH)2D) and reactive oxygen species (ROS), two integral signaling molecules of the cell, is poorly understood. This is striking, given that both factors are involved in cancer cell regulation and metabolism. Mitochondria (mt) dysfunction is one of the main drivers of cancer, producing more mitochondria, higher cellular energy, and ROS that can enhance oxidative stress and stress tolerance responses. To study the effects of 1,25(OH)2D on metabolic and mt dysfunction, we used the vitamin D receptor (VDR)‐sensitive MG‐63 osteosarcoma cell model. Using biochemical approaches, 1,25(OH)2D decreased mt ROS levels, membrane potential (ΔΨmt), biogenesis, and translation, while enforcing endoplasmic reticulum/mitohormetic stress adaptive responses. Using a mitochondria‐focused transcriptomic approach, gene set enrichment and pathway analyses show that 1,25(OH)2D lowered mt fusion/fission and oxidative phosphorylation (OXPHOS). By contrast, mitophagy, ROS defense, and epigenetic gene regulation were enhanced after 1,25(OH)2D treatment, as well as key metabolic enzymes that regulate fluxes of substrates for cellular architecture and a shift toward non‐oxidative energy metabolism. ATACseq revealed putative oxi‐sensitive and tumor‐suppressing transcription factors that may regulate important mt functional genes such as the mTORC1 inhibitor, DDIT4/REDD1. DDIT4/REDD1 was predominantly localized to the outer mt membrane in untreated MG‐63 cells yet sequestered in the cytoplasm after 1,25(OH)2D and rotenone treatments, suggesting a level of control by membrane depolarization to facilitate its cytoplasmic mTORC1 inhibitory function. The results show that 1,25(OH)2D activates distinct adaptive metabolic responses involving mitochondria to regain redox balance and control the growth of osteosarcoma cells. © 2021 The Authors. JBMR Plus published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research. [ABSTRACT FROM AUTHOR]

In spite of significant advances in the understanding of glioma biology and pathology, survival remains poor. Therefore, it is still of great significance to further explore the key factors involved in tumorigenesis and development in glioma and find potential new therapeutic targets. Here, we show that thyroid hormone receptor interactor 4 (TRIP4) is highly expressed in glioma cells and tissues. Patients of glioma with high expression of TRIP4 possess poor overall survival. Knockdown of TRIP4 inhibited tumor cell proliferation, metastasis, and apoptosis suppression, whereas overexpression of TRIP4 displays the opposite effects. Further research showed that TRIP4 promoted glioma progression through regulating DDIT4 expression and subsequent activation of mTOR signaling. DDIT4 overexpression restored the inhibition of tumor growth by TRIP4 knockdown in vitro and in vivo. Consistently, mTOR activity inhibition reversed TRIP4 overexpression-mediated tumor promotion in vitro and in vivo. Moreover, molecular mechanism exploration demonstrates that TRIP4 functions as a specific transcriptional activator to anchor at the promoter region of DDIT4 gene (−196 to −11) to regulate its transcription and such regulation was affected by HIF1α. Clinically, TRIP4 expression is positively correlated with DDIT4 expression in glioma samples based on tissue microarray analysis and both of their high expression predicts the malignancy of the disease. Altogether, our findings identify TRIP4 as a critical promoter of glioma progression by targeting DDIT4 and mTOR signaling successively and suggest that TRIP4-DDIT4 axis has potential to be a novel therapeutic target in glioma treatment. [Display omitted] • TRIP4 was highly expressed in glioma cells and tissues and patients of glioma with high expression of TRIP4 possess poor overall survival. • TRIP4 knockdown effectively led to the inhibited proliferative capacity, invasive ability and the enhanced apoptosis induction in glioma cells. • TRIP4 transcriptionally regulated DDIT4 via anchoring at its promoter region and further activated mTOR signaling in glioma cells. • DDIT4 overexpression or mTOR inhibition reversed TRIP4 knockdown or overexpression-mediated tumor delay or promotion in vitro and in vivo. • TRIP4 expression is positively correlated with DDIT4 expression in glioma samples and their high expression predicts the severity of glioma. [ABSTRACT FROM AUTHOR]

Background: Various diagnostic and prognostic tools exist in colorectal cancer (CRC) due to multiple genetic and epigenetic alterations causing the disease. Today, the expression of RNAs is being used as prognostic markers for cancer. Methods: In the current study, various dysregulated RNAs in CRC were identified via bioinformatics prediction. Expression of several of these RNAs were measured by RT-qPCR in 48 tissues from CRC patients as well as in colorectal cancer stem cell-enriched spheroids derived from the HT-29 cell line. The relationships between the expression levels of these RNAs and clinicopathological features were analyzed. Results: Our bioinformatics analysis determined 11 key mRNAs, 9 hub miRNAs, and 18 lncRNAs which among them 2 coding RNA genes including DDIT4 and SULF1 as well as 3 non-coding RNA genes including TPTEP1, miR-181d-5p, and miR-148b-3p were selected for the further investigations. Expression of DDIT4, TPTEP1, and miR-181d-5p showed significantly increased levels while SULF1 and miR-148b-3p showed decreased levels in CRC tissues compared to the adjacent normal tissues. Positive relationships between DDIT4, SULF1, and TPTEP1 expression and metastasis and advanced stages of CRC were observed. Additionally, our results showed significant correlations between expression of TPTEP1 with DDIT4 and SULF1. Conclusions: Our findings demonstrated increased expression levels of DDIT4 and TPTEP1 in CRC were associated with more aggressive tumor behavior and more advanced stages of the disease. The positive correlations between TPTEP1 as non-coding RNA and both DDIT4 and SULF1 suggest a regulatory effect of TPTEP1 on these genes. [ABSTRACT FROM AUTHOR]

Diabetic Retinopathy (DR) is a major cause of visual dysfunction, yet much remains unknown regarding the specific molecular events that contribute to diabetes-induced retinal pathophysiology. Herein, we review the impact of oxidative stress on DR, and explore evidence that supports a key role for the stress response protein regulated in development and DNA damage (REDD1) in the development of diabetes-induced oxidative stress and functional defects in vision. It is well established that REDD1 mediates the cellular response to a number of diverse stressors through repression of the central metabolic regulator known as mechanistic target of rapamycin complex 1 (mTORC1). A growing body of evidence also supports that REDD1 acts independent of mTORC1 to promote oxidative stress by both enhancing the production of reactive oxygen species and suppressing the antioxidant response. Collectively, there is strong preclinical data to support a key role for REDD1 in the development and progression of retinal complications caused by diabetes. Furthermore, early proof-of-concept clinical trials have found a degree of success in combating ischemic retinal disease through intravitreal delivery of an siRNA targeting the REDD1 mRNA. Overall, REDD1-associated signaling represents an intriguing target for novel clinical therapies that go beyond addressing the symptoms of diabetes by targeting the underlying molecular mechanisms that contribute to DR. [Display omitted] • Diabetes-induced hyperglycemia causes oxidative stress in the retina. • Oxidative stress contributes to the development of diabetic retinopathy. • Diabetes promotes expression of the stress response protein REDD1 in retina. • REDD1 promotes ROS production and suppresses the retinal antioxidant response. • REDD1 contributes to diabetes-induced retinal pathology and deficits in vision. [ABSTRACT FROM AUTHOR]

Sunlight exposure of the skin is associated with both risks and benefits. On one hand, sunlight ultraviolet (UV) radiation can cause skin cancer through signature DNA mutations. On the other hand, it can be absorbed in the skin by 7‐dehydrocholesterol to instigate endogenous synthesis of vitamin D to regulate anticancer effects. Thus, protecting one's skin from sunlight to avoid skin cancer may lead to impaired vitamin D levels arguing for sensible sun exposure practices. To limit cancer, vitamin D metabolites can promote uncharacterized and diverse sets of events such as repair responses to DNA damage, apoptosis of malignant cells, and suppression of immune surveillance, proliferation and angiogenesis. Recent findings also suggest that part of the anticancer effects of vitamin D within squamous cell carcinoma—a type of skin cancer most directly linked to sun exposure—involves the DDIT4‐mTOR catabolic signalling pathway to enhance cell autophagy. As mTOR activity and cellular metabolism are modulated as part of the DNA damage response, insights into the means by which mTOR can be controlled by vitamin D to suppress cancer is of molecular and clinical importance. Overall, the research so far suggests that presence of vitamin D through sunlight exposure and supplementation are beneficial for human health in the face of cancer. [ABSTRACT FROM AUTHOR]

Chronic myeloid leukemia (CML) is a hematopoietic malignancy driven by the fusion gene BCR::ABL1. Drug resistance to tyrosine kinase inhibitors (TKIs), due to BCR::ABL1 mutations and residual leukemia stem cells (LSCs), remains a major challenge in CML treatment. Here, we revealed the requirement of the vitamin D receptor (VDR) in the progression of CML. VDR was upregulated by BCR::ABL1 and highly expressed in CML cells. Interestingly, VDR knockdown inhibited the proliferation of CML cells driven by both BCR::ABL1 and TKI-resistant BCR::ABL1 mutations. Mechanistically, VDR transcriptionally regulated DDIT4 expression; reduced DDIT4 levels upon VDR knockdown triggered DNA damage and senescence via p53 signaling activation in CML cells. Furthermore, VDR deficiency not only suppressed tumor burden and progression in primary CML mice but also reduced the self-renewal capacity of CML-LSCs. Together, our study demonstrated that targeting VDR is a promising strategy to overcome TKI resistance and eradicate LSCs in CML., (© The Author(s) (2023). Published by Oxford University Press on behalf of Journal of Molecular Cell Biology, CEMCS, CAS.)

Ataxia telangiectasia (AT) is a rare, severe, and ineluctably progressive multisystemic neurodegenerative disease. Histone deacetylase 4 (HDAC4) nuclear accumulation has been related to neurodegeneration in AT. Since treatment with glucocorticoid analogues has been shown to improve the neurological symptoms that characterize this syndrome, the effects of dexamethasone on HDAC4 were investigated. In this paper, we describe a novel nonepigenetic function of HDAC4 induced by dexamethasone, through which it can directly modulate HIF‐1a activity and promote the upregulation of the DDIT4 gene and protein expression. This new HDAC4 transcription regulation mechanism leads to a positive effect on autophagic flux, an AT‐compromised biological pathway. This signaling was specifically induced by dexamethasone only in AT cell lines and can contribute in explaining the positive effects of dexamethasone observed in AT‐treated patients. [ABSTRACT FROM AUTHOR]

Sirtuins have emerged as a promising novel class of anti-cancer drug targets. Inhibition of SIRT1 and SIRT2 induces apoptosis in cancer cells and they play multifaceted roles in regulating autophagy. In the present study, we found that salermide, a SIRT1/2-specific inhibitor or small interfering RNAs (siRNAs) to block SIRT1/2 expression could induce autophagy in human NSCLC cells. Moreover, SIRT1/2 inhibition increased the expression levels of ATF4 and DDIT4 and downregulated p-RPS6KB1 and p-EIF4EBP1, two downstream molecules of mTORC1. Moreover, ATF4 or DDIT4 knockdown attenuated salermide-induced autophagy, suggesting that SIRT1/2 inhibition induced autophagy through the ATF4-DDIT4-mTORC1 axis. Mechanistically, SIRT1/2 inhibition led to HSPA5 acetylation and dissociation from EIF2AK3, leading to ER stress response and followed by upregulation of ATF4 and DDIT4, triggering autophagy. Silencing of the autophagic gene ATG5 in lung cancer cells resulted in increased apoptotic cell death induced by SIRT1/2 inhibition. Our data show that inhibition of SIRT1/2 induces pro-survival autophagy via acetylation of HSPA5 and subsequent activation of ATF4 and DDIT4 to inhibit the mTOR signaling pathway in NSCLC cells. These findings suggest that combinatorial treatment with SIRT1/2 inhibitors and pharmacological autophagy inhibitors is an effective therapeutic strategy for cancer therapy. [ABSTRACT FROM AUTHOR]

Background/Aims: miR221 might have an important role in human embryo development. However, little is known about the function of miR221 in the human embryo. The aim of this study was to evaluate miR221 expression in human placental tissue, and to analyze the relationship between miR221 and target genes. Methods: The human placentas tissue samples were collected from healthy pregnant women who were willing to terminate their pregnancy. The total RNA isolation and microRNA reverse transcription quantification were performed by TaqMan microRNA assay and qRT-PCR. Results: The results showed that miR221 expression was significantly higher in 55- to 71-day placenta (mean value=0.1049) than that in 38- to 54-day (the mean value=0.0133) (p<0.001). miR221 targeting genes, such as PIK3R1, CDKN1B, CDKN1C, DDIT4, and FOS, were detected in human placenta tissue, but only DDIT4 was significantly decreased with development (mean value: 0.0101 for 38~54 days, 0.0021 for 55~71 days, p<0.001). Further analysis showed that only DDIT4 was negatively correlated with miR221 expression (DDIT4: r=-0.396, p=0.033; PI3KR: r=0.322, p=0.089; CDKN1B: r=0.298, p=0.128; CDKN1C: r=0.198, p=0.304; FOS: r=0.171, p=0.347). Conclusion: These findings indicate that miR221 might play an important role in human placental development by precisely regulating the DDIT4 expression. [ABSTRACT FROM AUTHOR]

As one of the most important phthalates, di-isononyl phthalate (DINP) has been widely used as a common plasticizer in the food and personal care products sectors. In our previous study, we found that DINP can induce autophagy of ovarian granulosa cells; while the underlying mechanism is unclear. In the study, we showed that DINP exposure could induce autophagy of ovarian granulosa cells and KGN cells, accompanied with the increase in the mRNA and protein level of DDIT4. Furthermore, overexpression of DDIT4 were shown to induce autophagy of KGN cells; while knockdown of DDIT4 inhibited DINP-induced autophagy, implying that DDIT4 played an important role in DINP-induced autophagy of ovarian granulosa cells. There were three putative binding sites of transcription factor ATF4 in the promoter region of DDIT4 gene, suggesting that DDIT4 might be regulated by ATF4. Herein, we found that overexpression of ATF4 could upregulate the expression of DDIT4 in KGN cells, while knockdown of ATF4 inhibited its expression. Subsequently, ATF4 was identified to bind to the promoter region of DDIT4 gene and promote its transcription. The expression of ATF4 was also increased in the DINP-exposed granulosa cells, and ATF4 overexpression promoted autophagy of KGN cells; whereas knockdown of ATF4 alleviated DINP-induced upregulation of DDIT4 and autophagy of the cells. Taken together, DINP triggered autophagy of ovarian granulosa cells through activating ATF4/DDIT4 signals. [Display omitted] • DINP up-regulates DDIT4 expression in ovarian granulosa cells. • DDIT4 is essential for DINP-induced autophagy of ovarian granulosa cells. • ATF4 promotes gene transcription of DDIT4. • ATF4 is involved in DINP-induced up-regulation of DDIT4 in ovarian granulosa cells. • DINP induces autophagy of ovarian granulosa cells via ATF4/DDIT4 signals. [ABSTRACT FROM AUTHOR]

The present study aimed to establish a model of palmitic acid (PA)-induced insulin resistance (IR) in C2C12 cells and to determine the mechanism underlying how resveratrol (RSV) improves IR. C2C12 cells were divided into the control (CON), PA, PA + RSV, PA + RSV + DNA damage-inducible transcript 4 (DDIT4)-small interfering (si)RNA and PA + RSV + MHY1485 (mTOR agonist) groups. Glucose contents in culture medium and triglyceride contents in cells were determined. Oil red O staining was performed to observe the pathological changes in the cells. Reverse transcription-quantitative PCR and western blotting were conducted to evaluate the mRNA and protein expression levels, respectively, of DDIT4, mTOR, p70 ribosomal protein S6 kinase (p70S6K), insulin receptor substrate (IRS)-1, PI3K, AKT and glucose transporter 4 (GLUT4). Compared with in the CON group, glucose uptake was decreased, cellular lipid deposition was increased, phosphorylated (p)-IRS-1, p-mTOR and p-p70S6K protein expression levels were increased, and p-PI3K, p-AKT, GLUT4 and DDIT4 protein expression levels were decreased in the PA group. By contrast, compared with in the PA group, culture medium glucose content and cellular lipid deposition were decreased, p-PI3K, p-AKT, GLUT4 and DDIT4 protein expression levels were increased, p-IRS-1 protein expression levels were decreased, and mTOR and p70S6K mRNA and protein expression levels were decreased in the PA + RSV group. Compared with in the PA + RSV group, DDIT4 protein and mRNA expression levels were reduced in the PA + RSV + DDIT4-siRNA group, but showed no change in the PA + RSV + MHY1485 group. Following transfection with DDIT4-siRNA or treatment with MHY1485, the effects of RSV on improving IR and lipid metabolism were weakened, mTOR and p70S6K protein expression levels were upregulated, p-PI3K, p-AKT and GLUT4 protein expression levels were down-regulated, p-IRS-1 protein expression levels were upregulated, and culture medium glucose content and cellular lipid deposition were increased. In conclusion, RSV may improve PA-induced IR in C2C12 cells through the DDIT4/mTOR/IRS-1/PI3K/AKT/GLUT4 signaling pathway, as well as via improvements in glucose and lipid metabolism. [ABSTRACT FROM AUTHOR]

REDD1 is a transcriptional target gene of p53 and HIF-1, and an inhibitor of mTOR (mechanistic target of rapamycin) complex 1 (mTORC1)-signaling through PP2A-dependent interaction, making it an important convergence point of both tumor suppression and cell growth pathways. In accordance with this positioning, REDD1 levels are transcriptionally upregulated in response to a variety of cellular stress factors such as nutrient deprivation, hypoxia and DNA damage. In the absence of such conditions, and in particular where growth factor signaling is activated, REDD1 expression is typically negligible; therefore, it is necessary to induce REDD1 prior to experimentation or detection in model systems. Here, we evaluated the performance of a commercially available polyclonal antibody recognizing REDD1 by Western blotting in the presence of thapsigargin, a pharmacological inducer of ER stress well known to upregulate REDD1 protein expression. Further, REDD1 antibody specificity was challenged in HEK-293 cells in the presence of RNA interference and with a REDD1 -/- mouse embryonic fibroblast knockout cell line. Results showed reproducibility and specificity of the antibody, which was upheld in the presence of thapsigargin treatment. We conclude that this antibody can be used to reliably detect REDD1 endogenous expression in samples of both human and mouse origin.

Regulation of RNA substrate selectivity of m6A demethylase ALKBH5 remains elusive. Here, we identify RNA-binding motif protein 33 (RBM33) as a previously unrecognized m6A-binding protein that plays a critical role in ALKBH5-mediated mRNA m6A demethylation of a subset of mRNA transcripts by forming a complex with ALKBH5. RBM33 recruits ALKBH5 to its m6A-marked substrate and activates ALKBH5 demethylase activity through the removal of its SUMOylation. We further demonstrate that RBM33 is critical for the tumorigenesis of head-neck squamous cell carcinoma (HNSCC). RBM33 promotes autophagy by recruiting ALKBH5 to demethylate and stabilize DDIT4 mRNA, which is responsible for the oncogenic function of RBM33 in HNSCC cells. Altogether, our study uncovers the mechanism of selectively demethylate m6A methylation of a subset of transcripts during tumorigenesis that may explain demethylation selectivity in other cellular processes, and we showed its importance in the maintenance of tumorigenesis of HNSCC. [Display omitted] • RBM33 binds m6A and regulates ALKBH5-mediated m6A demethylation selectivity • RBM33 activates ALKBH5 demethylase activity via suppression of ALKBH5 SUMOylation • RBM33/ALKBH5 modulates m6A-mediated DDIT4 mRNA decay and DDIT4/TXNIP-based autophagy • Suppression of RBM33/ALKBH5 activity inhibits HNSCC and primary patient cell growth Yu et al. identify RBM33 as a new m6A-binding protein that forms a complex with ALKBH5 and mediates m6A demethylation of selected transcripts by regulating ALKBH5 substrate accessibility and activity. In HNSCC cells, highly expressed RBM33 promotes HNSCC tumorigenesis by stabilizing DDIT4 in an m6A-dependent manner, thereby inducing autophagy. [ABSTRACT FROM AUTHOR]