Search

Diabetic nephropathy (DN) is one of the most serious complications of advanced diabetes, and increases patient mortality. Recently, epigenetics-mediated hyperglycemic memory in pathological process of DN has received attention. The purpose of this study was to determine the underlying mechanism by which sirt7 modulates hyperglycemic memory in DN. In glomerular endothelial cells (GECs) cultured in high glucose and glomeruli of DN patients and rats, an increase in p65 phosphorylation and endothelial adhesion molecule levels persisted after glucose normalization but was reversed by glucose normalization associated with death-associated protein kinase-3 (DAPK3) knockout or DAPK3 inhibitor. High glucose-mediated decrease in sirt7, the deacetylase modulating H3K18-acetylation (H3K18ac), was sustained after normoglycemia. Sirt7 overexpression accompanied by glucose normalization suppressed DAPK3 expression and inflammation in GECs. Moreover, sh-sirt7-induced inflammation was inhibited by si-DAPK3. Furthermore, sirt7 and H3K18ac were located at the DAPK3 promoter region. ELK1 was found to combine with sirt7. si-ELK1 supplemented with normoglycemia inhibited high glucose-induced DAPK3 expression and inflammation in GECs. ELK1 overexpression-mediated inflammation was inhibited by si-DAPK3. In addition, ELK1 and sirt7 were located at the same promoter region of DAPK3. ELK1 overexpression enhanced DAPK3 promoter activity, which disappeared after specific binding site mutation. In vivo, sirt7 overexpression decreased inflammation and improved renal function during insulin treatment of DN rats, whereas insulin alone did not work. Our data demonstrated high glucose-mediated mutual inhibition between sirt7 and ELK1 induced DAPK3 transcription and inflammation despite normoglycemia in GECs, thus forming a vicious cycle and participating in the occurrence of hyperglycemic memory in DN.

Sepsis-induced acute kidney injury (AKI) is a common in clinic. Circular RNAs (circRNAs) play significant roles in ameliorating AKI. The purpose of this study was aimed to identify the role of circ_0074371 and the potential action mechanism in sepsis-induced AKI.AKI patients and healthy individual serum samples were collected and the relative expression of circ_0074371 was measured by real-time polymerase chain reaction (RT-PCR). HK2 cells were treated with different dose (0, 2.5, 5 and 10 μg/ml) lipopolysaccharide (LPS) to establish the AKI cell model. The cell viability and apoptosis of HK2 cells were detected using cell counting kit-8 (CCK-8) and flow cytometry, respectively. The contents of malondialdehyde (MDA), and superoxide dismutase (SOD) were evaluated using the relative commercial kits. The IL-1β and TNF-α levels in cell culture supernatants were measured by ELISA. The interaction relationship between miR-330-5p and circ_0074371 or ELK1 was predicted by Targetscan database and further confirmed by the dual-luciferase reporter assay system.The circ_0074371 expression was up-regulated in sepsis patients and LPS-induced HK2 cells. Silencing circ_0074371 promoted HK2 cells viability and inhibited the HK2 cells apoptosis. miR-330-5p inhibitor weakened circ_0074371 inhibitor-induced cell viability, apoptosis and oxidative stress. Further mechanism analysis showed that circ_0074371 acted as a sponge for miR-330-5p to increase ELK1 expression level. Importantly, miR-330-5p downregulation or ELK1 upregulation reversed the action of circ_0074371 knockdown on LPS-induced HK2 cells.Knockdown of circ_0074371 ameliorated LPS-induced HK2 cells apoptosis, inflammation and oxidative stress via regulating miR-330-5p/ELK1, opening a new window into the pathogenesis AKI.

Circular RNAs (circRNAs) are characterized as a class of new noncoding RNAs and function in tumorigenesis of colorectal cancer (CRC). In our study, the molecule mechanism of circ_0022340 in CRC was investigated. For this aim, quantitative real-time polymerase chain reaction (RT-qPCR) was used to test gene expression in CRC cells. Cell function assays including 5-ethynyl-20-deoxyuridine (EdU), colony formation and transwell investigated the proliferation and migration capacity in CRC cells. Luciferase reporter and RNA immunoprecipitation (RIP)assays determined the interaction between circRNA, miRNA and mRNA. Western blot was used to test protein expression. An immunohistochemistry assay was used to assess the tumor growth in vivo. Results showed that Circ_0022340 was highly expressed in CRC cells. Circ_0022340 was formed from exon 5 to 6 of the synaptotagmin 7 (SYT7). Silencing of circ_0022340 suppressed CRC cell proliferation and migration. Functionally, circ_0022340 recruited heterogeneous nuclear ribonucleoprotein C (HNRNPC) to stabilize EBF1 mRNA and thereby activated SYT7. Moreover, circ_0022340 targeted miR-382-5p to up-regulate ETS transcription factor ELK1 (ELK1). It is concluded that Circ_0022340 promoted colorectal cancer progression via recruiting HNRNPC to stabilize EBF1 mRNA and thereby activated SYT7 or miR-382-5p/ELK1 axis, which might provide a novel target for CRC treatment.

In previous studies, we found that B7 homolog 3 (B7-H3) was highly expressed in lung adenocarcinoma (LUAD) and promoted epithelial-to-mesenchymal transition (EMT) of LUAD cells. However, the underlying molecular mechanism is unclear. This study is aimed at evaluating the role of Ets-like protein 1 (ELK1) as a transcriptional regulator of B7-H3 for mediating the development and progression of LUAD in vitro and in vivo. We confirmed that ELK1 is highly expressed in LUAD and is associated with poor patient prognosis. ELK1 was found to promote proliferation, invasion, migration, and EMT of LUAD cells through in vivo and in vitro experiments. In terms of mechanism, ELK1 binds to the B7-H3 promoter region and induces the upregulation of B7-H3 in LUAD. Our data suggest that ELK1 plays an important role in the development of LUAD and could be used as a prognostic marker and therapeutic target for LUAD.

Obesity‐associated type 2 diabetes (T2D) is on the rise in the United States due to the obesity epidemic, and 60% of T2D patients develop diabetic retinopathy (DR) in their lifetime. Chronic inflammation is a hallmark of obesity and T2D and a well‐accepted major contributor to DR, and retinal photoreceptors are a major source of intraocular inflammation and directly contribute to vascular abnormalities in diabetes. However, how diabetic insults cause photoreceptor inflammation is not well known. In this study, we used a high‐fat diet (HFD)‐induced T2D mouse model and cultured photoreceptors treated with palmitic acid (PA) to decipher major players that mediate high‐fat‐induced photoreceptor inflammation. We found that PA‐elicited microRNA‐150 (miR‐150) decreases with a consistent upregulation of ETS‐domain transcription factor 1 (Elk1), a downstream target of miR‐150, in PA‐elicited photoreceptor inflammation. We compared wild‐type (WT) and miR‐150 null (miR‐150−/−) mice fed with an HFD and found that deletion of miR‐150 exacerbated HFD‐induced photoreceptor inflammation in conjunction with upregulated ELK1. We further delineated the critical cellular localization of phosphorylated ELK1 at serine 383 (pELK1S383) and found that decreased miR‐150 exacerbated the T2D‐induced inflammation in photoreceptors by upregulating ELK1 and pELK1S383, and knockdown of ELK1 alleviated PA‐elicited photoreceptor inflammation.

Mantle cell lymphoma (MCL) is a haematologic malignancy. The proteasome inhibitor (PI) bortezomib has been approved to treat MCL, but resistance has emerged through mechanisms that remain unclear. This study aimed to explore the mechanism of PI resistance in MCL and identify new targets for this patient subgroup. Carfilzomib-resistant (CR) MCL cell lines and primary samples were used for both in vitro and in vivo experiments to identify gene expression and explore their related signalling pathways. We first identified mucin 20 (MUC20) suppression in carfilzomib-resistant MCL models. MUC20 overexpression sensitized cells to carfilzomib in vitro and in vivo. MUC20 expression was inversely related to activation of c-Met and the downstream p44/42 MAPK pathway. c-Met activation with hepatocyte growth factor (HGF) induced PI resistance, while c-Met inhibition restored PI sensitivity. Carfilzomib resistance and depressed MUC20 expression were associated with enhanced proteasome activity and higher expression of proteassemblin (POMP), a chaperone for catalytically active proteasome assembly. c-Met and POMP were associated through binding and induction of MAPK-regulated ELK1 to the POMP promoter. Our data reveal that c-Met signalling activation enhanced proteasome capacity as a mechanism of PI resistance, and MUC20 expression may be a useful biomarker for PI therapy.

The chromodomain helicase DNA-binding protein CHD8 is among the most frequently found de-novo mutations in autism (1–3). Unlike most other autism-risk genes, CHD8 mutations appear to be fully penetrant (4). Despite its prominent disease involvement, little known about its molecular function. Based on sequence homology, CHD8 is believed to be a chromatin regulator, but mechanisms for its genomic targeting and its role on chromatin are unclear. Here, we developed a human cell model carrying conditional CHD8 loss-of-function alleles. Full knockout CHD8 was required for the viability of undifferentiated human embryonic stem (ES) cells, whereas postmitotic neurons survived following CHD8 depletion. However, chromatin accessibility maps and transcriptional profiling revealed that CHD8 is a potent general chromatin activator, enhancing transcription of its direct target genes, including a large group of autism genes. CHD8’s genomic binding sites in human neurons were significantly enriched for ELK1 (ETS) motifs. Moreover, positive CHD8-dependent chromatin remodeling was enhanced at ELK1 motif-containing CHD8 binding sites. ELK1 was the most prominent ETS factor expressed in human neurons and was necessary for CHD8 to target the sites that contained the ELK1 motif, demonstrating a cooperative interaction between ELK1 and CHD8 on chromatin. We also observed potential role of CHD8 in ELK1 localization on nuclear compartments in a transcription-stage-dependent manner. Finally, inhibition of ELK1 activity or ELK1 knockdown that enhances the neurogenesis from embryonic stem cells (ES) was dependent on the presence of CHD8. In summary, our results establish that CHD8 is a strong activator of chromatin accessibility and transcription in neurons and reveals a role in regulating many high-risk autism genes. Additionally, we show there is molecular and functional interdependence of CHD8 and ELK1 in chromatin binding of CHD8, nuclear interaction of ELK1, and neurogenesis enhancement. These data imply the involvement of the MAPK/ERK pathway effector ELK1 in pathogenesis of autism caused by CHD8 mutations (5).

Mitogen activated protein kinase (MAPK) activation and neurogenesis are known to play a role in neuronal survival during hibernation. Herein, we investigate the activity of c-Jun N-terminal kinases (JNK) and Ets like-1 protein (Elk1) kinase involved in cell survival, as well as the expression of proliferating cell nuclear antigen (PCNA), a cell proliferation marker, in the brain of the frog Pelophylax esculentus. The study was conducted on female and male frogs collected during the annual cycle. Our results demonstrated that JNK activity increased during the hibernating phase in relation to the active phase. Interestingly, P-Elk1 levels were positively correlated with P-JNK levels, suggesting that the JNK/Elk1 pathway is pivotal in mediating neuroprotective adaptations that are essential to successful hibernation. On the contrary, we detected higher PCNA expression levels during the active period compared with the hibernating period. A sex dimorphism was observed in the expression levels of P-JNK/P-Elk1 that were specifically higher in males, and in the expression of PCNA reporting higher levels in female brains. Much remains to be learned regarding the regulation of hibernation, however, our findings provide new insights into the role of MAPK and proliferative pathways in hibernation, adding new knowledge concerning the mechanisms activated in the brain of ectothermic species to counteract the damage resulting from extreme temperatures.

Long noncoding RNAs (lncRNAs) have been identified as functional modulators in human tumors. The purpose of our study was to determine the expressing trend, clinical significance and functions of lncRNA LINC02381(LINC02381) in osteosarcoma. We observed that the expression of LINC02381 and cell division cycle-associated protein 4 (CDCA4) were distinctly increased in osteosarcoma specimens and cells, while miR-503–5p expression was decreased. Additionally, ETS transcription factor ELK1 (ELK1) could bind directly to the LINC02381 promoter region and activate its transcription. Clinical assays revealed that high LINC02381 was associated with advanced clinical progress and poor clinical outcome. Functionally, knockdown of LINC02381 suppressed the proliferation, migration and invasion of osteosarcoma cells. What’s more, LINC02381 could down-regulate CDCA4 via sponging miR-503–5p, and there existed a negative correlation between LINC02381 expression and miR-503–5p expression in 92 osteosarcoma samples. Rescue experiments proved the carcinogenic role of LINC02381/miR-503–5p/CDCA4 axis in osteosarcoma progression. Overall, our data illustrated how LINC02381 played an oncogenic role in osteosarcoma and might offer a novel diagnostic and prognostic biomarker and potential therapeutic target for osteosarcoma.

Several studies have reported that long non-coding RNAs (LncRNAs) were associated with the progression of acute kidney injury (AKI). However, the role and regulation mechanism of lncRNA122049 in ischemic AKI remains unknown. In the present study, we found that lncRNA 122049 protected against the ischemia/reperfusion (I/R) induced apoptosis in BUMPT cells. Mechanistically, the lncRNA 122049 directly sponged miR-330-5p, then increased the expression of ELK1(ETS transcription factor ELK1) to decrease renal cell apoptosis. In addition, miR-330-5p inhibitor completely reversed the pro-apoptotic effect of LncRNA 122049 siRNA on I/R-induced BUMPT cells apoptosis. Finally, overexpression of lncRNA 122049 attenuated ischemic mice AKI via targeting of the miR-330-5p/ELK1 axis. Collectively, the data demonstrated that LncRNA 122049 prevented the I/R-induced renal cell apoptosis via regulation of the miR-330-5p/ELK1 axis, which brings new insights into the pathogenesis and potential targeted treatment of ischemic AKI.

ETS transcription factor (ELK1) stimulates the expression of genes at the onset of the cell cycle and participates in early developmental programming. Here, we investigated whether alterations of ELK1 lead to progression of bladder cancer (BCa), a main neoplasm of urinary tract, and clarified the function of ELK1 in BCa. Using the GEO database, we identified ELK1 as the most significantly overexpressed gene in BCa, which was substantiated in the acquired clinical samples and cells. Silencing of ELK1 inhibited the malignant phenotype of BCa cells. Further analysis revealed that ELK1 synergized with histone deacetylase 2 (HDAC2) to specifically bind to the synaptotagmin like 1 (SYTL1) promoter, thereby repressing SYTL1 transcription and protein expression. Depletion of SYTL1 reversed the repressive effects of ELK1 depletion on the malignant phenotype of BCa cells. Our in vitro findings were reproduced in vivo on a nude mouse tumorigenic model. Together, our results reveal that ELK1, through suppression of SYTL1 via HDAC2, supports the malignant phenotype of BCa cells.

Mutational activation of KRAS is a common oncogenic event in lung cancer, yet effective therapies are still lacking. Here, we identify B cell lymphoma 6 (BCL6) as a lynchpin in KRAS-driven lung cancer. BCL6 expression was increased upon KRAS activation in lung tumor tissue in mice and was positively correlated with the expression of KRAS-GTP, the active form of KRAS, in various human cancer cell lines. Moreover, BCL6 was highly expressed in human KRAS-mutant lung adenocarcinomas and was associated with poor patient survival. Mechanistically, the MAPK/ERK/ELK1 signaling axis downstream of mutant KRAS directly regulated BCL6 expression. BCL6 maintained the global expression of prereplication complex components; therefore, BCL6 inhibition induced stalling of the replication fork, leading to DNA damage and growth arrest in KRAS-mutant lung cancer cells. Importantly, BCL6-specific knockout in lungs significantly reduced the tumor burden and mortality in the LSL-KrasG12D/+ lung cancer mouse model. Likewise, pharmacological inhibition of BCL6 significantly impeded the growth of KRAS-mutant lung cancer cells both in vitro and in vivo. In summary, our findings reveal a crucial role of BCL6 in promoting KRAS-addicted lung cancer and suggest BCL6 as a therapeutic target for the treatment of this intractable disease.

Background Glutathione Peroxidase 4 (GPX4) is a key protein that inhibits ferroptosis. However, its biological regulation and mechanism in endometrial cancer (EC) have not been reported in detail. Methods The expression of GPX4 in EC tissues was determined by TCGA databases, qRT-PCR, Western blot, and immunohistochemistry (IHC). The effects of GPX4 on EC cell proliferation, migration, apoptosis, and tumorigenesis were studied in vivo and in vitro. In addition, ETS Transcription Factor ELK1 (ELK1) was identified by bioinformatics methods, dual-luciferase reporter assay, and chromatin immunoprecipitation (ChIP). Pearson correlation analysis was used to evaluate the association between ELK1 and GPX4 expression. Results The expression of GPX4 was significantly up-regulated in EC tissues and cell lines. Silencing GPX4 significantly inhibited the proliferation, migration ability, induced apoptosis, and arrested the cell cycle of Ishikawa and KLE cells. Knockdown of GPX4 accumulated intracellular ferrous iron and ROS, disrupted MMP, and increased MDA levels. The xenograft tumor model also showed that GPX4 knockdown markedly reduced tumor growth in mice. Mechanically, ELK1 could bind to the promoter of GPX4 to promote its transcription. In addition, the expression of ELK1 in EC was positively correlated with GPX4. Rescue experiments confirmed that GPX4 knockdown could reverse the strengthens of cell proliferation and migration ability and the lower level of Fe2+ and MDA caused by upregulating ELK1. Conclusion The results of the present study suggest that ELK1 / GPX4 axis plays an important role in the progress of EC by promoting the malignant biological behavior and inducing ferroptosis of EC cells, which provides evidence for investigating the potential therapeutic strategies of endometrial cancer.

Electrostatic protein/DNA interactions arise from the neutralization of the DNA phosphodiester backbone as well as coupled exchanges by charged protein residues as salt bridges or with mobile ions. Much focus has been and continues to be paid to interfacial ion pairs with DNA. The role of extra-interfacial ionic interactions, particularly as dynamic drivers of DNA sequence selectivity, remain poorly known. The ETS family of transcription factors represents an attractive model for addressing this knowledge gap given their diverse ionic composition in primary structures that fold to a tightly conserved DNA-binding motif. To probe the importance of extra-interfacial salt bridges in DNA recognition, we compared the salt-dependent binding by Elk1 with ETV6, two ETS homologs differing markedly in ionic composition. While both proteins exhibit salt-dependent binding with cognate DNA that corresponds to interfacial phosphate contacts, their nonspecific binding diverges from cognate binding as well as each other. Molecular dynamics simulations in explicit solvent, which generated ionic interactions in agreement with the experimental binding data, revealed distinct salt-bridge dynamics in the nonspecific complexes formed by the two proteins. Impaired DNA contact by ETV6 resulted in fewer backbone contacts in the nonspecific complex, while Elk1 exhibited a redistribution of extra-interfacial salt bridges via residues that are non-conserved between the two ETS relatives. Thus, primary structure variation in ionic residues can encode highly differentiated specificity mechanisms in a highly conserved DNA-binding motif.

Abnormal expression of circular RNA (circRNA) is closely related to the occurrence and development of many cancers. By screening the expression of circRNA, we identified a novel circRNA termed as has_circ_0023326 in laryngeal squamous cell carcinoma (LSCC). We verified the expression of circPPFIA1 and found that it was upregulated in LSCC tissues compared to the adjacent normal tissues. Functional studies were carried out to detect the effect of circPPFIA1 expression on the phenotype of LSCC cells. These results suggest that circPPFIA1 knockdown can suppress the proliferation, migration, and invasion of LSCC cells, while circPPFIA1 overexpression can promote these processes. Mechanistically, miR-340-3p was predicted to be the target miRNA sponged by circPPFIA1 as confirmed through the luciferase assay and rescue experiments. In addition, miR-340-3p was found to target ELK1 and inhibit its expression. Taken together, circPPFIA1 promotes the progression of LSCC via the miR-340-3p/ELK1 signaling axis, which may serve as a novel prognostic or therapeutic target for LSCC.

Malignant melanoma, the most aggressive form of skin cancer, is characterized by high prevalence of BRAF/NRAS mutations and hyperactivation of extracellular signal-regulated kinase 1 and 2 (ERK1/2), mitogen-activated protein kinases (MAPK), leading to uncontrolled melanoma growth. Efficacy of current targeted therapies against mutant BRAF or MEK1/2 have been hindered by existence of innate or development of acquired resistance. Therefore, a better understanding of the mechanisms controlled by MAPK pathway driving melanogenesis will help develop new treatment approaches targeting this oncogenic cascade. Here, we identify E3 ubiquitin ligase PARK2 as a direct target of ELK1, a known transcriptional effector of MAPK signaling in melanoma cells. We show that pharmacological inhibition of BRAF-V600E or ERK1/2 in melanoma cells increases PARK2 expression. PARK2 overexpression reduces melanoma cell growth in vitro and in vivo and induces apoptosis. Conversely, its genetic silencing increases melanoma cell proliferation and reduces cell death. Further, we demonstrate that ELK1 is required by the BRAF-ERK1/2 pathway to repress PARK2 expression and promoter activity in melanoma cells. Clinically, PARK2 is highly expressed in WT BRAF and NRAS melanomas, but it is expressed at low levels in melanomas carrying BRAF/NRAS mutations. Overall, our data provide new insights into the tumor suppressive role of PARK2 in malignant melanoma and uncover a novel mechanism for the negative regulation of PARK2 via the ERK1/2-ELK1 axis. These findings suggest that reactivation of PARK2 may be a promising therapeutic approach to counteract melanoma growth.

As one of the most common cancers in female, ovarian cancer (OC) has become a serious public burden now. Mounting researches have indicated long noncoding RNAs (lncRNAs) can affect many biological processes including cancer development. LncRNA LBX2-AS1 was identified to be an oncogene in some cancers, but the role of LBX2-AS1 in OC remains to be elucidated. Bioinformatics analysis and experiments including ChIP, RT-qPCR, RIP, luciferase reporter, western blot and CCK-8 were performed to explore the role of LBX2-AS1 in OC. LBX2-AS1 expression was markedly increased in OC tissues and cell lines. Functionally, LBX2-AS1 silencing inhibited cell proliferation, migration and stemness but facilitated cell apoptosis in OC. Moreover, depletion of LBX2-AS1 suppressed tumor growth of OC in vivo. Mechanically, LBX2-AS1 was activated by transcriptional factor ELK1. ELK1 enhanced the expression of LBX2-AS1 in OC cells. In addition, miR-4784 was confirmed to be sponged by LBX2-AS1. There was a negative expression correlation between LBX2-AS1 and miR-4784 in OC tissues. Subsequently, KDM5C was identified to be a direct target of miR-4784 in OC cells. KDM5C was negatively regulated by miR-4784 and positively regulated by LBX2-AS1 in terms of expression level. Upregulation of KDM5C reversed the inhibitory effect of LBX2-AS1 depletion on the progression of OC. This study proved that ELK1 activated-LBX2-AS1 aggravated the progression of OC by targeting the miR-4784/KDM5C axis, suggesting that LBX2-AS2 may be a promising diagnostic biomarker of OC.

Background Diabetic nephropathy (DN), the most common microvascular complication in patients with diabetes, induces kidney failure. Previous research showed that endothelial-to-mesenchymal transition (EndMT) of human glomerular endothelial cells (HGECs) is involved in the progression of DN. Moreover, SET domain-containing protein 8 (SETD8), ETS-domain containing protein (ELK1) and BTB and CNC homology 1 (bach1) all participate in endothelial injury. In this study, we hypothesize that the SETD8/ELK1/bach1 functional axis is involved in mediating EndMT in diabetic nephropathy. Methods Immunohistochemistry, Western blotting and qPCR were performed to determine the protein and mRNA levels of genes in HGECs and the kidney tissues of participants and rats. Immunofluorescence, Co-IP and GST pulldown assays were performed to verify the direct interaction between SETD8 and ELK1. ChIP and dual-luciferase assays were performed to determine the transcriptional regulation of bach1 and Snail. AVV-SETD8 injection in rat kidney was used to verify the potential protective effect of SETD8 on DN. Results Our current study showed that hyperglycaemia triggered EndMT by increasing Snail expression both in vitro and in vivo. Moreover, high glucose increased bach1 expression in HGECs, positively regulating Snail and EndMT. As a transcription factor, ELK1 was augmented and participated in hyperglycaemia-induced EndMT via modulation of bach1 expression. Moreover, ELK1 was found to associate with SETD8. Furthermore, SETD8 negatively regulated EndMT by cooperating with bach1 to regulate Snail transcription. Furthermore, histone H4-Lys-20 monomethylation (H4K20me1), which is downstream of SETD8, was accompanied by ELK1 localization at the same promoter region of bach1. ELK1 overexpression enhanced bach1 promoter activity, which disappeared after specific binding site deletion. Mutual inhibition between ELK1 and SETD8 was found in HGECs. In vivo, SETD8 overexpression decreased ELK1 and bach1 expression, as well as EndMT. Moreover, SETD8 overexpression improved the renal function of rats with DN. Conclusions SETD8 cooperates with ELK1 to regulate bach1 transcription, thus participating in the progression of DN. In addition, SETD8 interacts with bach1 to modulate Snail transcription, thus inducing EndMT in DN. SETD8 plays a core role in the SETD8/ELK1/bach1 functional axis, which participates in hyperglycaemia-mediated EndMT in DN, and SETD8 may be a potential therapeutic target for DN. Trial registration ChiCTR, ChiCTR2000029425. 2020/1/31, http://www.chictr.org.cn/showproj.aspx?proj=48548

Purpose Osteosarcoma is a type of bone malignancy that mainly occurred in teenagers. This investigation is aimed to clarify the effect of long non-coding RNA (lncRNA) LINC00662 on the proliferation, migration, and invasion in osteosarcoma and explore the underlying action mechanisms. Methods The mRNA expression of LINC00662 was determined by real-time quantitative polymerase chain reaction. Cell proliferation, migration, and invasion were evaluated by 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide, wound healing, and transwell assays, respectively. A dual-luciferase reporter assay was used to validate the target relationships Between microRNA (miR)-30b-3p and LINC00662/ ETS domain-containing protein 1 (ELK1). Western blotting was performed to determine the protein expression of ELK1. Xenograft model was established to evaluate the effects of LINC00662 silencing on tumor growth in vivo. Results LncRNA LINC00662 and ELK1 were significantly increased, while miR-30b-3p was reduced in osteosarcoma tissues. The results of functional experiments indicated that transfection of small hairpin (sh)-LINC00662 and miR-30b-3p mimics repressed the migration, invasion, and proliferation of osteosarcoma cells. LncRNA LINC00662 also appeared to sponge miR-30b-3p in order to affect the expression of ELK1. Simultaneously, there were weak negative correlations between the expression of miR-30b-3p and LINC00662/ELK1 in osteosarcoma tissues. Rescue experiments suggested that ELK1 overexpression and downregulation of miR-30b-3p reversed the suppressive effects of sh-LINC00662 on the cell migration, invasion, and proliferation in osteosarcoma. Conclusions The current study indicated that knockdown of LINC00662 repressed cell migration, invasion, and proliferation through sponging miR-30b-3p to regulate the expression of ELK1 in osteosarcoma. These results may uncover a promising target for the treatment of osteosarcoma.

Liver metastasis of colorectal cancer (CRLM) is the most common cause of CRC‐related mortality, and is typically caused by interactions between CRC cells and the tumour microenvironment (TME) in the liver. However, the molecular mechanisms underlying the crosstalk between tumour‐derived extracellular vesicle (EV) miRNAs and the TME in CRLM have yet to be fully elucidated. The present study demonstrated that highly metastatic CRC cells released more miR‐181a‐5p‐rich EVs than cells which exhibit a low metastatic potential, in‐turn promoting CRLM. Additionally, we verified that FUS mediated packaging of miR‐181a‐5p into CRC EVs, which in‐turn persistently activated hepatic stellate cells (HSCs) by targeting SOCS3 and activating the IL6/STAT3 signalling pathway. Activated HSCs could secrete the chemokine CCL20 and further activate a CCL20/CCR6/ERK1/2/Elk‐1/miR‐181a‐5p positive feedback loop, resulting in reprogramming of the TME and the formation of pre‐metastatic niches in CRLM. Clinically, high levels of serum EV containing miR‐181a‐5p was positively correlated with liver metastasis in CRC patients. Taken together, highly metastatic CRC cells‐derived EVs rich in miR‐181a‐5p could activate HSCs and remodel the TME, thereby facilitating liver metastasis in CRC patients. These results provide novel insight into the mechanism underlying liver metastasis in CRC.

Gastric cancer, is the fourth most common tumour type yet, ranks second in terms of the prevalence of cancer‐related deaths worldwide. CXXC finger protein 4 (CXXC4) has been considered as a novel cancer suppressive factor, including gastric cancer. This study attempted to investigate the possible function of CXXC4 in gastric cancer and the underlying mechanism. The binding of the ETS domain‐containing protein‐1 (ELK1) to the long non‐coding RNA MIR100HG promoter region was identified. Then, their expression patterns in gastric cancer tissues and cells (SGC7901) were detected. A CCK‐8 assay was used to detect SGC7901 cell proliferation. Subsequently, SGC7901 cells were co‐cultured with CD3+ T cells, followed by measurement of CD3+ T cell proliferation, magnitude of IFN‐γ+ T cell population and IFN‐γ secretion. A nude mouse model was subsequently developed for in vivo validation of the in vitro results. Low CXXC4 expression was found in SGC7901 cells. Nuclear entry of ELK1 can be inhibited by suppression of the extent of ELK1 phosphorylation. Furthermore, ELK1 is able to bind the MIR100HG promoter. Overexpression of CXXC4 resulted in weakened binding of ELK1 to the MIR100HG promoter, leading to a reduced proliferative potential of SGC7901 cells, and an increase in IFN‐γ secretion from CD3+ T cells. Moreover, in vivo experiments revealed that CXXC4 inhibited immune escape of gastric cancer cells through the ERK1/2 axis. Inhibition of the CXXC4/ELK1/MIR100HG pathway suppressed the immune escape of gastric cancer cells, highlighting a possible therapeutic target for the treatment of gastric cancer.

The epithelial-mesenchymal transition (EMT) process is a key priming activity of fibroblasts in pulmonary fibrosis during silicosis. Ets-like protein-1 (Elk-1) is a critical modulator that promotes functional changes in cells, and the effects are mediated by oxidative stress (OS). However, whether ELK-1 is involved in EMT of silicosis remains unclear. In addition, researchers have found that Elk-1 is involved in the expression of the gene zc3h12a, which encodes the protein MCPIP1, and MCPIP1 is a member of the zinc finger Cys-Cys-Cys-His (CCCH)-type protein family. A previous study from our lab showed that ZC3H4, which is also a member of the CCCH-type protein family, critically affected the regulation of EMT during silicosis. However, it has not yet been elucidated if ELK-1 acts at the promoter for zc3h4 to increase its expression in a mechanism that is similar to that of the zc3h12a gene and whether such regulation ultimately controls EMT. Therefore, we explored the correlation between ELK-1 and ZC3H4 expression and tested the underlying mechanisms affecting ELK-1 activation induced by silica. Our study identifies that SiO2-mediated EMT via ELK-1, with the upstream activity of OS and the downstream signaling of ZC3H4 expression resulting in enhanced EMT. These findings suggest that the nuclear transcription factor ELK-1 may be useful as a novel target for the treatment of pulmonary fibrosis.

Pancreatic cancer is a malignant disease with poor prognosis. Emerging evidences have showed that miR-597-5p is closely related to tumor development. However, the functional roles of miR-597-5p in pancreatic cancer remain unknown. This study aimed to investigate the expression of miR-597-5p in pancreatic cancer tissues and cells, and explored its regulatory mechanism during pancreatic cancer progression. Pancreatic cancer and adjacent tissues were obtained to detect the expression of miR-597-5p by RT-qPCR. Cell growth, apoptosis, and related protein expression were, respectively, tested by CCK-8 assay, cell formation, wound healing, Transwell assay, flow cytometry, and western blotting. Finally, the pancreatic cancer mice model was constructed. In vitro and in vivo results showed that miR-597-5p expression was down-regulated in pancreatic cancer tissues and cell lines, and increased the overall survival of pancreatic cancer patients. Moreover, miR-597-5p decreased pancreatic cancer cell viability, reduced relative wound width, suppressed colony formation and decreased invasive cell number, as well as reduced the expression of proliferating cell nuclear antigen (PCNA), Ki67, Cyclin D1, N-cad, and Bcl-2. Meanwhile, it increased pancreatic cancer cell apoptosis and the expression of E-cad, cleaved caspase 3, and Bax. The dual-luciferase reporter assay confirmed miR-597-5p could directly target e-twenty six like-1 (ELK1) oncogene. The reduction of cell growth and the induction of cell apoptosis induced by miR-597-5p were reversed by ELK1. In addition, miR-597-5p inhibited the growth of pancreatic cancer in vivo. This study demonstrated that miR-597-5p may be a novel suppressor of pancreatic cancer. It inhibits pancreatic cancer cell growth and promotes apoptosis by the down-regulation of ELK1 in vitro and in vivo.

KIAA0101, previously identified as PCNA-associated factor, is overexpressed among almost majority of human cancers and has emerged as an important regulator of cancer progression; however, its function in human nasopharyngeal carcinoma (NPC) remain unknown. Integrated bioinformatics approaches were employed to determine the KIAA0101 expressions in the NPC samples. Lentiviral vectors carrying KIAA0101 shRNA were constructed and stable transfected cells were validated by qRT-PCR and western blot. Cellular functions were then evaluated by MTT, colony formation, Brdu staining, and flow cytometry. Mechanistic studies were systematically investigated by UCSC Genome Browser, GEO, UALCAN, QIAGEN, PROMO and JASPAR, ChIP, and the cBioPortal, et al. The results showed that KIAA0101 ranked top overexpressed gene lists in GSE6631 dataset. KIAA0101 was highly expressed in NPC tissues and cell lines. Furthermore, knockdown of KIAA0101 significantly inhibited cell proliferation and DNA replication, promoted apoptosis and cell cycle arrest in vitro. Meanwhile, the mechanistic study revealed that MAP kinase phosphorylation-dependent activation of ELK1 may enhance neighbor gene expressions of KIAA0101 and TRIP4 by binding both promotor regions in the NPC cells. Taken together, our findings indicate that overexpression of KIAA0101 activated by MAP kinase phosphorylation-dependent activation of ELK1 may play an important role in NPC progression.

Cancer stem cells (CSCs) have been implicated in the growth and progression of several types of human cancer. The technology to derive and establish CSCs in vitro could be a critical tool for under...

Background Both hormone-sensitive and castration- and enzalutamide-resistant prostate cancers (PCa) depend on the ternary complex factor (TCF) protein ELK1 to serve as a tethering protein for the androgen receptor (AR) to activate a critical set of growth genes. The two sites in ELK1 required for AR binding are conserved in other members of the TCF subfamily, ELK3 and ELK4. Here we examine the potential utility of the three proteins as prognosticators of disease recurrence in PCa. Methods Transcriptional activity assays; Retrospective analysis of PCa recurrence using data on 501 patients in The Cancer Genome Atlas (TCGA) database; Unpaired Wilcoxon rank-sum test and multiple comparison correction using the Holm's method; Spearman's correlations; Kaplan-Meier methods; Univariable and multivariable Cox regression analyses; LASSO-based penalized Cox regression models; Time-dependent area under the receiver operating characteristic (ROC) curve. Results ELK4 but not ELK3 was coactivated by AR similar to ELK1. Tumor expression of neither ELK3 nor ELK4 was associated with disease-free survival (DFS). ELK1 was associated with higher clinical T-stage, pathology T-stage, Gleason score, prognostic grade, and positive lymph node status. ELK1 was a negative prognosticator of DFS, independent of ELK3, ELK4, clinical T-stage, pathology T-stage, prognostic grade, lymph node status, age, and race. Inclusion of ELK1 increased the abilities of the Oncotype DX and Prolaris gene panels to predict disease recurrence, correctly predicting disease recurrence in a unique subset of patients. Conclusions ELK1 is a strong, independent prognosticator of disease recurrence in PCa, underscoring its unique role in PCa growth. Inclusion of ELK1 may enhance the utility of currently used prognosticators for clinical decision making in prostate cancer.

This study investigates the role of circular RNA (circRNA) hsa_circ_0000515 in cervical cancer and the underlying mechanism associated with microRNA-326 (miR-326). hsa_circ_0000515 and ETS transcription factor ELK1 (ELK1) were initially over-expressed and miR-326 was down-regulated in cervical cancer tissues and cells. Low hsa_circ_0000515 expression was found to be associated with favorable prognosis of patients with cervical cancer. A series of mimics, inhibitors, over-expression plasmids or siRNAs were introduced into cervical cancer cells to alter the expression of hsa_circ_0000515, miR-326 and ELK1. In vitro experiments exhibited that silencing of hsa_circ_0000515 or upregulation of miR-326 resulted in suppressed proliferation and invasion, along with induced apoptosis and autophagy of cervical cancer cells. Dual-luciferase reporter assay, RNA pull-down and RIP assays highlighted that hsa_circ_0000515 was able to act as a ceRNA of miR-326 to increase ELK1. Furthermore, enhancement of ELK1 expression resulted in enhanced proliferation and invasion but repressed apoptosis and autophagy of cervical cancer cells. In vivo experiments further confirmed the suppressed tumor growth by hsa_circ_0000515 silencing. Our findings demonstrated that hsa_circ_0000515 acts as a tumor promoter in cervical cancer. The study provides evidence for targeting hsa_circ_0000515 for therapeutic purposes in treating cervical cancer.

Huntington’s disease (HD) is a chronic neurodegenerative disorder characterized by a late clinical onset despite ubiquitous expression of the mutant Huntingtin gene ( HTT ) from birth. Transcriptional dysregulation is a pivotal feature of HD. Yet, the genes that are altered in the prodromal period and their regulators, which present opportunities for therapeutic intervention, remain to be elucidated. Using transcriptional and chromatin profiling, we found aberrant transcription and changes in histone H3K27acetylation in the striatum of R6/1 mice during the presymptomatic disease stages. Integrating these data, we identified the Elk-1 transcription factor as a candidate regulator of prodromal changes in HD. Exogenous expression of Elk-1 exerted beneficial effects in a primary striatal cell culture model of HD, and adeno-associated virus-mediated Elk-1 overexpression alleviated transcriptional dysregulation in R6/1 mice. Collectively, our work demonstrates that aberrant gene expression precedes overt disease onset in HD, identifies the Elk-1 transcription factor as a key regulator linked to early epigenetic and transcriptional changes in HD, and presents evidence for Elk-1 as a target for alleviating molecular pathology in HD.

Background: Co-occurrence of TERT (telomerase reverse transcriptase) promoter (TERTp) mutations with BRAF/RAS mutations is associated with significantly more aggressive thyroid cancer. TERTp mutati...

Cerebral vasospasm (CVS) is a common complication of subarachnoid hemorrhage (SAH) with high deformity rates and cerebral vascular smooth muscle cells (VSMCs) phenotypic switch is considered to be involved in the regulation of CVS. However, to the best of the authors' knowledge, its underlying molecular mechanism remains to be elucidated. Peroxisome proliferator-activated receptor β/δ (PPARβ/δ) has been demonstrated to be involved in the modulation of vascular cells proliferation and maintains the autoregulation function of blood vessels. The present study investigated the potential effect of PPARβ/δ on CVS following SAH. A model of SAH was established by endovascular perforation on male adult Sprague-Dawley rats, and the adenovirus PPARβ/δ (Ad-PPARβ/δ) was injected via intracerebroventricular administration prior to SAH. The expression levels of phenotypic markers α-smooth muscle actin and embryonic smooth muscle myosin heavy chain were measured via western blotting or immunofluorescence staining. The basilar artery diameter and vessel wall thickness were evaluated under fluorescence microscopy. SAH grade, neurological scores, brain water content and brain swelling were measured to study the mechanisms of PPARβ/δ on vascular smooth muscle phenotypic transformation. It was revealed that the expression levels of synthetic proteins were upregulated in rats with SAH and this was accompanied by CVS. Activation of PPARβ/δ using Ad-PPARβ/δ markedly upregulated the contractile proteins elevation, restrained the synthetic proteins expression and attenuated SAH-induced CVS by regulating the phenotypic switch in VSMCs at 72 h following SAH. Furthermore, the preliminary study demonstrated that PPARβ/δ downregulated ERK activity and decreased the expression of phosphorylated (p-)ETS domain-containing protein Elk-1 and p-p90 ribosomal S6 kinase, which have been demonstrated to serve an important role in VSMC phenotypic change. Additionally, it was revealed that Ad-PPARβ/δ could positively improve CVS by ameliorating the diameter of the basilar artery and mitigating the thickness of the vascular wall. Furthermore, subsequent experiments demonstrated that Ad-PPARβ/δ markedly reduced the brain water content and brain swelling and improved the neurological outcome. Taken together, the present study identified PPARβ/δ as a useful regulator for the VSMCs phenotypic switch and attenuating CVS following SAH, thereby providing novel insights into the therapeutic strategies of delayed cerebral ischemia.

While miRs have been extensively studied in the context of malignancy and tumor progression, their functions in regulating T-cell activation are less clear. In initial studies, we found reduced levels of miR-15a/16 at 3 to 18 h post-T-cell receptor (TCR) stimulation, suggesting a role for decreased levels of this miR pair in shaping T-cell activation. To further explore this, we developed an inducible miR15a/16 transgenic mouse model to determine how elevating miR-15a/16 levels during early stages of activation would affect T-cell proliferation and to identify TCR signaling pathways regulated by this miR pair. Doxycycline (DOX)-induced expression of miR-15a/16 from 0 to 18 h post-TCR stimulation decreased ex vivo T-cell proliferation as well as in vivo antigen-specific T-cell proliferation. We also combined bioinformatics and proteomics approaches to identify the mitogen-activated protein kinase kinase 1 (MEK1) (Map2k1) as a target of miR-15a/16. MEK1 targeting by miR-15a/16 was confirmed using miR mimics that decreased Map2k1 mRNA containing the 3'-UTR target nucleotide sequence (UGCUGCUA) but did not decrease Map2k1 containing a mutated control sequence (AAAAAAAA). Phosphorylation of downstream signaling molecules, extracellular signal-regulated protein kinase 1/2 (ERK1/2) and Elk1, was also decreased by DOX-induced miR-15a/16 expression. In addition to MEK1, ERK1 was subsequently found to be targeted by miR-15a/16, with DOX-induced miR-15a/16 reducing total ERK1 levels in T cells. These findings show that TCR stimulation reduces miR-15a/16 levels at early stages of T-cell activation to facilitate increased MEK1 and ERK1, which promotes the sustained MEK1-ERK1/2-Elk1 signaling required for optimal proliferation.

Rationale: Targeting vascular smooth muscle cell (VSMC) phenotypic switching is a promising therapeutic approach for atherosclerosis. Dysregulation of PGC1α (peroxisome proliferator-activated receptor gamma, coactivator 1α), a key regulator of cellular energy metabolism, has been implicated in the pathogenesis of atherosclerosis, yet its role in atherosclerosis remains controversial. Objective: The current study aimed to determine whether and how PGC1α in VSMCs regulates atherosclerosis progression. Methods and Results: We generated transgenic rabbits with SMC-specific PGC1α overexpression and showed that these rabbits developed significantly less aortic atherosclerosis than their nontransgenic littermates after high-cholesterol diet feeding, while total plasma cholesterol levels were similar. As indicated by the restored expression of VSMC differentiation marker genes, the high-cholesterol diet-induced phenotypic switching in the aortic media was largely reversed in transgenic rabbits, accompanied by decreased levels of synthetic phenotype genes, proinflammatory cytokines, adhesion molecules, macrophage infiltration, MMPs (matrix metalloproteinases), reactive oxygen species production and senescence. Ex vivo studies further showed that VSMC-specific PGC1α overexpression markedly suppressed the promotive effect of high-cholesterol diet feeding on the association of SRF (serum response factor) with ELK1 (ETS transcription factor ELK1), a TCF (ternary complex factor) that acts as a myogenic repressor in VSMCs, thereby preserving the VSMC contractile phenotype. Furthermore, knockdown of PGC1α remarkably increased ERK (extracellular signal-regulated kinase)1/2-ELK-1 signaling, which promoted phenotypic switching and proliferation of cultured rabbit VSMCs. In addition, we showed that PGC1α can regulate EGFR (epidermal growth factor receptor)-ERK1/2 MAPK (mitogen-activated protein kinase) signaling via modulating PPARγ (peroxisome proliferator-activated receptor γ) activity in RVSMCs (rabbit vascular smooth muscle cells). Finally, we showed that these beneficial results of SMC-specific PGC1α overexpression can be extrapolated from rabbits to human VSMCs and clinical settings. Conclusions: We demonstrated a critical role of PGC1α in maintaining the contractile phenotype of VSMCs and highlighted the therapeutic potential of PGC1α for atherosclerosis.

Elk-1 is a transcription factor that binds together with a dimer of the serum response factor (SRF) to the serum-response element (SRE), a genetic element that connects cellular stimulation with gene transcription. Elk-1 plays an important role in the regulation of cellular proliferation and apoptosis, thymocyte development, glucose homeostasis and brain function. The biological function of Elk-1 relies essentially on the interaction with other proteins. Elk-1 binds to SRF and generates a functional ternary complex that is required to activate SRE-mediated gene transcription. Elk-1 is kept in an inactive state under basal conditions via binding of a SUMO-histone deacetylase complex. Phosphorylation by extracellular signal-regulated protein kinase, c-Jun N-terminal protein kinase or p38 upregulates the transcriptional activity of Elk-1, mediated by binding to the mediator of RNA polymerase II transcription (Mediator) and the transcriptional coactivator p300. Strong and extended phosphorylation of Elk-1 attenuates Mediator and p300 recruitment and allows the binding of the mSin3A-histone deacetylase corepressor complex. The subsequent dephosphorylation of Elk-1, catalyzed by the protein phosphatase calcineurin, facilitates the re-SUMOylation of Elk-1, transforming Elk-1 back to a transcriptionally inactive state. Thus, numerous protein–protein interactions control the activation cycle of Elk-1 and are essential for its biological function.

Papillary thyroid carcinoma (PTC) characterized by distant metastasis is a major public health issue among women worldwide. LncRNA LINC01638 is reportedly a critical oncogene in the development of certain cancers. However, the biological function of LINC01638 in PTC is currently unclear. The goal of this study was to identify LINC01638 expression level and its role in PTC progression. The expression of LINC01638 was detected applying qRT-PCR. CCK-8 assay, colony formation assay, immunofluorescence staining and flow cytometric analysis were performed to assess cell proliferation and cell cycle. In addition, cell migration and invasion were examined via wound healing assay, transwell assay and western blot analysis. We found that LINC0163 was upregulated in PTC cells compared with normal thyroid gland epithelial cell line Nthy-ori3-1. ELK1 could act as a transcription factor of LINC01638 and induce LINC01638 expression. LINC01638 silencing inhibited cell proliferation, migration and invasion, and obstructed the progress of TPC-1 cell cycle. LINC0163 silencing activated Axin2 while suppressing the expressions of β-catenin, Cyclin-D1 and c-MYC. Rescue experiment utilizing the transfection of Axin2 overexpression plasmid weakened LINC01638 overexpression-enhanced TPC-1 cell proliferation, metastasis, cell cycle progress and Wnt/β-catenin pathway. These results indicate that LINC0163 regulates PTC progression via inhibition of Wnt/β-catenin and activation of Axin2, which may develop into a novel therapeutic strategy for PTC treatment., Graphical Abstract

Background Ventilator-induced lung injury (VILI) is a common complication in the treatment of respiratory diseases with high morbidity and mortality. ETS-domain containing protein (Elk1) and Matrix metalloproteinase (MMP) 9 are involved in VILI, but the roles have not been fully elucidated. This study examined the mechanisms of the activation of MMP-9 and Elk1 regulating barrier function in VILI in vitro and in vivo. Methods For the in vitro study, Mouse lung epithelial cells (MLE-12) were pre-treated with Elk1 siRNA or MMP-9 siRNA for 48 h prior to cyclic stretch at 20% for 4 h. For the in vivo study, C57BL/6 mice were pre-treated with Elk1 siRNA or MMP-9 siRNA for 72 h prior to 4 h of mechanical ventilation. The expressions of Elk1, MMP-9, Tissue inhibitor of metalloproteinase 1 (TIMP-1), E-cadherin, and occludin were measured by Western blotting. The intracellular distribution of E-cadherin and occludin was shown by immunofluorescence. The degree of pulmonary edema and lung injury were evaluated by Hematoxylin–eosin (HE) staining, lung injury scores, Wet/Dry (W/D) weight ratio, total cell counts, and Evans blue dye. Results 20% cyclic stretch and high tidal volume increases the expressions of Elk1, MMP-9, and TIMP-1, increases the ratio of MMP-9/TIMP-1, decreases the E-cadherin and occludin level. Elk1 siRNA or MMP-9 siRNA reverses the degradations of E-cadherin, occludin, and the ratio of MMP-9/TIMP-1 caused by cyclic stretch. Elk1 siRNA decreases the MMP-9 level with or not 20% cyclic stretch and high tidal volume. Conclusions The results demonstrate mechanical stretch damages the tight junctions and aggravates the permeability in VILI, Elk1 plays an important role in affecting the tight junctions and permeability by regulating the balance of MMP-9 and TIMP-1, thus indicating the therapeutic potential of Elk1 to treat VILI.

Purpose: KIF26B is a member of the kinesin superfamily that is up-regulated in various tumors, including breast cancer (BC), which can promote tumor progression. This study aimed to investigate the potential function of KIF26B in BC, and the underlying mechanisms, focusing mainly on cell proliferation. Methods: KIF26B expression was examined in BC tissue samples obtained from 99 patients. We performed MTS, EdU and flow cytometry assays to detect cell proliferation, and western blotting to measure the expression of cell cycle-related proteins in MDA-MB-231 and MDA-MB-468 cells following KIF26B knockdown. Promoter analysis was used to study the upstream regulatory mechanism of KIF26B. Results：KIF26B was upregulated in BC tissue samples. High expression of KIF26B was associated with clinicopathological parameters, such as positive lymph node metastasis, higher tumor grade and high proliferative index in BC tissue. Furthermore, knockdown of KIF26B expression inhibited MDA-MB-231 and MDA-MB-468 cell proliferation, arresting cells in the G1 phase of the cell cycle in vitro. Similarly, KIF26B silencing decreased the expression levels of Wnt, β-catenin and cell cycle-related proteins such as c-Myc, cyclin D1 and cyclin-dependent kinase 4, whilst increasing the expression of p27. Moreover, ELK1 could bind to the core promoter region of KIF26B and activate its transcription. Conclusion: KIF26B acts as an oncogene in BC that can promote development of BC by regulating multiple proteins involved in the cell cycle. ELK1 activates KIF26B transcription.

The tumor microenvironment contains various components, including cancer cells, tumor vessels, and cancer-associated fibroblasts, the latter of which are comprised of tumor-promoting myofibroblasts and tumor-suppressing fibroblasts. Multiple lines of evidence indicate that transforming growth factor-β (TGF-β) induces the formation of myofibroblasts and other types of mesenchymal (non-myofibroblastic) cells from endothelial cells. Recent reports show that fibroblast growth factor 2 (FGF2) modulates TGF-β-induced mesenchymal transition of endothelial cells, but the molecular mechanisms behind the signals that control transcriptional networks during the formation of different groups of fibroblasts remain largely unclear. Here, we studied the roles of FGF2 during the regulation of TGF-β-induced mesenchymal transition of tumor endothelial cells (TECs). We demonstrated that auto/paracrine FGF signals in TECs inhibit TGF-β-induced endothelial-to-myofibroblast transition (End-MyoT), leading to suppressed formation of contractile myofibroblast cells, but on the other hand can also collaborate with TGF-β in promoting the formation of active fibroblastic cells which have migratory and proliferative properties. FGF2 modulated TGF-β-induced formation of myofibroblastic and non-myofibroblastic cells from TECs via transcriptional regulation of various mesenchymal markers and growth factors. Furthermore, we observed that TECs treated with TGF-β were more competent in promoting in vivo tumor growth than TECs treated with TGF-β and FGF2. Mechanistically, we showed that Elk1 mediated FGF2-induced inhibition of End-MyoT via inhibition of TGF-β-induced transcriptional activation of α-smooth muscle actin promoter by myocardin-related transcription factor-A. Our data suggest that TGF-β and FGF2 oppose and cooperate with each other during the formation of myofibroblastic and non-myofibroblastic cells from TECs, which in turn determines the characteristics of mesenchymal cells in the tumor microenvironment.

Background/aim Signaling regulation of myeloid zinc finger 1 (MZF1) has been implicated in the progression of many human malignancies; however, the mechanistic action of MZF1 in triple-negative breast cancer (TNBC) progression remains elusive. In this study, the aim was to investigate the molecular mechanisms of MZF1 and its functional role in TNBC cellular migration and invasion. Materials and methods Hs578T and MDA-MB-231 cells were transfected to stably express the acidic domain of MZF1 (MZF160-72), or were transfected with MZF1-specific or ELK1-specific short hairpin RNA (shRNA). Changes in cell morphology and distributions of cellular proteins were observed and subsequently migration and invasion were measured by wound healing and transwell assays. Expression levels of epithelial-mesenchymal transition (EMT)-related genes were carried out using immunoblotting and quantitative reverse transcription-polymerase chain reaction (RT-PCR) assays. Data of transcriptional regulation were obtained from promoter-luciferase reporter and chromatin immunoprecipitation (ChIP) assays. Results Herein, we found that MZF1 in high-level MZF1-expressing TNBC cells is associated with cell migration, invasion, and mesenchymal phenotype. MZF1 interacted with the promoter region of insulin-like growth factor 1 receptor (IGF1R) to drive invasion and metastasis of high-level MZF1-expressing TNBC cells. Exogenous expression of the acidic domain of MZF1 repressed the binding of endogenous MZF1 to IGF1R promoter via blocking the interaction with ETS-like gene 1 (ELK1). This blockage not only caused MZF1 protein degradation, but also restrained ELK1 nuclear localization in high-level MZF1-expressing TNBC cells. MZF1, but not ELK1, was necessary for the retention of mesenchymal phenotype by repressing IGF1R promoter activity in TNBC cells expressing high levels of MZF1. Activation of the IGF1R-driven p38MAPK-ERα-slug-E-cadherin signaling axis mediated the conversion of mesenchymal cell to epithelial phenotype, caused by MZF1 destabilization. These results suggest that MZF1 is an oncogenic inducer. Conclusion Blocking of the MZF1/ELK1 interaction to reduce MZF1 protein stability by saturating the endogenous MZF1/ELK1 binding domains might be a promising therapeutic strategy for the treatment of high-level MZF1-expressing TNBC.

6-(Methylsulfinyl)hexyl isothiocyanate (6-MSITC) is a major bioactive compound in Wasabi. Although 6-MSITC is reported to have cancer chemopreventive activities in rat model, the molecular mechanism is unclear. In this study, we investigated the anticancer mechanisms using two types of human colorectal cancer cells (HCT116 p53+/+ and p53−/−). 6-MSITC caused cell cycle arrest in G2/M phase and induced apoptosis in both types of cells in the same fashion. Signaling data revealed that the activation of ERK1/2, rather than p53, is recruited for 6-MSITC-induced apoptosis. 6-MSITC stimulated ERK1/2 phosphorylation, and then activated ERK1/2 signaling including ELK1 phosphorylation, and upregulation of C/EBP homologous protein (CHOP) and death receptor 5 (DR5). The MEK1/2 inhibitor U0126 blocked all of these molecular events induced by 6-MSITC, and enhanced the cell viability in both types of cells in the same manner. These results indicated that ERK1/2-mediated ELK1/CHOP/DR5 pathway is involved in 6-MSITC-induced apoptosis in colorectal cancer cells. Abbreviations: CHOP: C/EBP homologous protein; DR5: death receptor 5; ELK1: ETS transcription factor; ERK1/2: extracellular signal-regulated kinase 1/2; JNK: Jun-N-terminal kinase; MAPK: mitogen-activated protein kinase; MEK1/2: MAP/ERK kinase 1/2; 6-MSITC: 6-(methylsulfinyl)hexyl isothiocyanate; MTT: 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide; PARP: poly(ADP-ribose) polymerase.

Despite their location at the cell surface, several receptor tyrosine kinases (RTK) are also found in the nucleus, as either intracellular domains or full length proteins. However, their potential nuclear functions remain poorly understood. Here we find that a fraction of full length Colony Stimulating Factor-1 Receptor (CSF-1R), an RTK involved in monocyte/macrophage generation, migrates to the nucleus upon CSF-1 stimulation in human primary monocytes. Chromatin-immunoprecipitation identifies the preferential recruitment of CSF-1R to intergenic regions, where it co-localizes with H3K4me1 and interacts with the transcription factor EGR1. When monocytes are differentiated into macrophages with CSF-1, CSF-1R is redirected to transcription starting sites, colocalizes with H3K4me3, and interacts with ELK and YY1 transcription factors. CSF-1R expression and chromatin recruitment is modulated by small molecule CSF-1R inhibitors and altered in monocytes from chronic myelomonocytic leukemia patients. Unraveling this dynamic non-canonical CSF-1R function suggests new avenues to explore the poorly understood functions of this receptor and its ligands., Receptor tyrosine kinases localize to the cell surface and have been suggested to also have nuclear function. Here the authors provide evidence that Colony Stimulating Factor-1 Receptor (CSF-1R) migrates to the nucleus upon CSF-1 stimulation in monocytes and that upon differentiation into macrophages, CSF-1R localizes to TSS, co-localizes with H3K4me3, and interacts with ELK and YY1.