Inhibition of matrix metalloproteinase-2 by halofuginone is mediated by the Egr1 transcription factor

Early growth response factor 1 upregulates pro-fibrotic genes through activation of TGF-β1/Smad pathway via transcriptional regulation of PAR1 in high-glucose treated HK-2 cells

Tubulointerstitial fibrosis (TIF) makes a key role in diabetic kidney disease (DKD). In this study, we revealed that the expressions of Egr1 and protease-activated receptor 1 (PAR1) were increased in renal tissues of DKD rats. In vitro experiments demonstrated that both Egr1 overexpression and high glucose (HG) condition could promote the expressions of PAR1, fibronectin (FN) and collagen I (COL I). Furthermore, HG stimulation enhanced the binding capacity of Egr1 to PAR1 promoter. Both HG condition and Egr1 upregulation could increase, and thrombin inhibitor did not affect activity of TGF-β1/Smad pathway via PAR1. Collectively, Egr1 is involved in TIF of DKD partly through activating TGF-β1/Smad pathway via transcriptional regulation of PAR1 in HG treated HK-2 cells.

Orally Administered Halofuginone-Loaded TPGS Polymeric Micelles Against Triple-Negative Breast Cancer: Enhanced Absorption and Efficacy with Reduced Toxicity and Metastasis

Background

Halofuginone (HF)-loaded TPGS polymeric micelles (HTPM) were successfully fabricated using the thin-film hydration technique. HTPM via intravenous injection have been demonstrated to exert an excellent anticancer effect against triple-negative breast cancer (TNBC) cells and subcutaneous xenografts. In the present study, we further explored the potential treatment effect and mechanism of orally administered HTPM alone and in combination with surgical therapy on TNBC in subcutaneous and orthotopic mouse models.

Methods

Herein, the stability and in vitro release behavior of HTPM were first evaluated in the simulated gastrointestinal fluids. Caco-2 cell monolayers were then used to investigate the absorption and transport patterns of HF with/without encapsulation in TPGS polymeric micelles. Subsequently, the therapeutic effect of orally administered HTPM was checked on subcutaneous xenografts of TNBC in nude mice. Ultimately, orally administered HTPM, combined with surgical therapy, were utilized to treat orthotopic TNBC in nude mice.

Results

Our data confirmed that HTPM exhibited good stability and sustained release in the simulated gastrointestinal fluids. HF was authenticated to be a substrate of P-glycoprotein (P-gp), and its permeability across Caco-2 cell monolayers was markedly enhanced via heightening intracellular absorption and inhibiting P-gp efflux due to encapsulation in TPGS polymeric micelles. Compared with HF alone, HTPM showed stronger tumor-suppressing effects in subcutaneous xenografts of MDA-MB-231 cells when orally administered. Moreover, compared with HTPM or surgical therapy alone, peroral HTPM combined with partial surgical excision synergistically retarded the growth of orthotopic TNBC. Fundamentally, HTPM orally administered at the therapeutic dose did not cause any pathological injury, while HF alone led to weight loss and jejunal bleeding in the investigated mice.

Conclusion

Taken together, HTPM could be applied as a potential anticancer agent for TNBC by oral administration.

Egr1 Knockdown Combined with an ACE Inhibitor Ameliorates Diabetic Kidney Disease in Mice: Blockade of Compensatory Renin Increase

BACKGROUND

Increased compensatory intrarenal renin diminishes the efficacy of angiotensin-converting enzyme inhibitors (ACEIs) and angiotensin receptor blockers (ARBs) in the treatment of diabetic kidney disease (DKD). Early growth response-1 (Egr1) is a crucial transcriptional factor in the progress of DKD and is a potential transcription factor of intrarenal renin according to bioinformatic analysis. However, whether inhibition of Egr1 can suppress compensatory renin increase in DKD is unclear.

METHODS

We generated a high-fat diet (HFD)/streptozotocin (STZ)-induced diabetic mouse model. The mice were treated with either enalapril (an ACEI) or enalapril combined with a shEgr1 plasmid, and age-matched DKD mice were used as controls. Urine microalbumin, urinary renin and kidney TGF-β1 were determined by enzyme-linked immunosorbent assay (ELISA). Hematoxylin and eosin (H&E) and Masson staining were used to determine renal pathological changes. Egr1, renin, TNF-α, and FN were measured by real-time quantitative PCR, Western blot, and immunohistochemistry. The SV40-MES13 murine mesangial cell line was transfected with pENTER-Egr1 plasmid and siEgr1.

RESULTS

Our results showed that enalapril increased the renin level of urinary and renal in DKD mice, while shEgr1 attenuated this effect. In addition, enalapril treatment reduced the levels of urinary microalbumin, TNF-α, TGF-β1 and FN, and alleviated the pathological changes, while shEgr1 strengthened these effects. The protein and mRNA expression of renin in the SV40 MES13 cells was upregulated and downregulated following overexpression and silence of Egr1, respectively.

CONCLUSION

Silence of Egr1 could alleviate renal injury in DKD by downregulating intrarenal renin.

Human p21-activated kinase 5 (PAK5) expression and potential mechanisms in relevant cancers: Basic and clinical perspectives for molecular cancer therapeutics

An oncogenic role, p21-activated kinase 5 (PAK5), has proven as a significant mediator for many cellular progression, which is expressed highly in human organs such as lung, liver, kidney, blood vessels endothelial cells and inflammatory cells. PAK5 was primitively detected in the cerebrum and accelerated the filopodia formation in neurocytes. It can reverse the effect of Rho and adjust its activity to mediate maintenance and development of nerve axon by binding with Cdc42-GTP. Moreover, PAK5 has been suggested to mediate protean, multitudinous and inscrutable functions in cancer. Currently, many researches indicated that PAK5 was dysregulated in ovarian cancer, cervical cancer, melanoma, osteosarcoma, renal carcinoma, breast cancer, gastric cancer and so on, which was involved in cell proliferation, apoptosis, migration and invasion. This review focuses the latest knowledge on the structure, expression, signalling pathway of PAK5, emphasizing its function in cancer.

Friend or foe, the role of EGR-1 in cancer

Early growth response-1 (EGR-1), also termed NEFI-A and Krox-24, as a multi-domain protein is implicated in several vital physiological processes, including development, metabolism, cell growth and proliferation. Previous studies have implied that EGR-1 was producing in response to the tissue injury, immune response and fibrosis. Meanwhile, emerging studies stressed the pronounced correlation of EGR-1 and human cancers. Nevertheless, the intricate mechanisms of cancer-reduce EGR-1 alteration still poorly characterized. In the review, we evaluated the effects of EGR-1 in tumor cell proliferation, apoptosis, migration, invasion and tumor microenvironment, and then, we dwell on the intricate signaling pathways that EGR-1 involved in. The aberrantly expressed of EGR-1 in cancers are expected to provide a new cancer therapy strategy or a new marker for assessing treatment efficacy.

NGFI-A Binding Protein 2 Promotes EGF-Dependent HNSCC Cell Invasion

NGFI-A binding protein 2 (NAB2) represses the transcriptional activation of early growth response protein-1 (EGR1), a tumor-suppressor. However, Epidermal Growth Factor (EGF) promotes tumor progression even with significant EGR1 upregulation. The molecular mechanism through which NAB2 is involved in cancer is largely unknown. Therefore, we evaluated how the NAB2-mediated suppression of EGR1 facilitates head and neck squamous cell carcinoma (HNSCC) cancer progression, in association with Sp1, which competes with EGR1 as a transcriptional regulator. The effect of NAB2 on EGR1/SP1 binding to the consensus promoter sequences of MMP2 and MMP9 was evaluated by chromatin immunoprecipitation (ChIP) and promoter luciferase assay. The correlation between EGR1-NAB2 expression and metastatic status was investigated using The Cancer Genome Atlas (TCGA) for HNSCC patients. Our data showed that NAB2 knockdown in FaDu and YD-10B HNSCC cells alleviated EGF-dependent increase of Matrigel invasion. In addition, NAB2 upregulation in EGF-treated FaDu cell diminishes EGR1 transcriptional activity, resulting in the upregulation of Sp1-dependent tumor-promoting genes. TCGA data analysis of 483 HNSCC tumors showed that higher levels of both EGR1 and NAB2 mRNA were significantly associated with metastasis, corresponding to in vitro results. Our data suggest that NAB2 upregulation facilitates EGF-mediated cancer cell invasion through the transactivation of Sp1-dependent tumor-promoting genes. These results provide insight into the paradoxical roles of EGF-EGR1 in cancer progression.

Halofuginone attenuates intervertebral discs degeneration by suppressing collagen I production and inactivating TGFβ and NF-кB pathway

Most low back pain is caused by intervertebral discs (IVD) degeneration, a disease that prevalence is increasing with age. Halofuginone, an analog of ferbrifugine isolated from plant Dichroa febrifuga, has drawn much attention in recent years for the wide range of bioactivities in malaria, cancer, fibrotic and autoimmune diseases. In this study, we evaluated the benefit effects of halofuginone in IVD degeneration treatment in a validated rabbit puncture model. Halofuginone treatment could attenuate disc degeneration by suppressing the decrease of discs height and nucleus pulposus signal strength. Besides, halofuginone treatment could suppress mRNA and protein expression of collagen I in nucleus pulposus. This might possibly due to the inactivation of transform growth factor-β (TGFβ) signal pathway by down-regulating p-Samd3 and up-regulating inhibitory Smad7. Then, we evaluated the effects of halofuginone treatment on nuclear factor of kappa B (NF-κB) signal pathway and its downstream pro-inflammatory cytokines. The level of p-p65 and p-IκBα was down-regulated in halofuginone treated group, indicating the inactivation of NF-κB signal pathway. The mRNA expression of interleukin 1β (IL-1β), tumor necrosis factor α (TNF-α), interleukin 6 (IL-6) and interleukin 8 (IL-8) was decreased in nucleus pulposus too, indicating the down-regulation of pro-inflammatory cytokines. In conclusion, halofuginone treatment could attenuate IVD degeneration and this was possibly due to suppressing of collagen I production and inactivation of TGFβ and NF-κB signal pathway in nucleus pulposus of degenerated discs. These results suggest that halofuginone has the potential for IVD degeneration treatment, but more research is needed to validate this.

Early Growth Response 1 (Egr1) Is a Transcriptional Activator of NOX4 in Oxidative Stress of Diabetic Kidney Disease

BACKGROUND

NADPH oxidase 4 (NOX4) plays a major role in renal oxidative stress of diabetic kidney disease (DKD). NOX4 was significantly increased in Egr1-expressing fibroblasts, but the relationship between Egr1 and NOX4 in DKD is unclear.

METHODS

For the evaluation of the potential relationship between Egr1 and NOX4, both were detected in HFD/STZ-induced mice and HK-2 cells treated with TGF-β1. Then, changes in NOX4 expression were detected in HK-2 cells and mice with overexpression and knockdown of Egr1. The direct relationship between Egr1 and NOX4 was explored via chromatin immunoprecipitation (ChIP).

RESULTS

We found increased levels of Egr1, NOX4, and α-SMA in the kidney cortices of diabetic mice and in TGF-β1-treated HK-2 cells. Overexpression or silencing of Egr1 in HK-2 cells could upregulate or downregulate NOX4 and α-SMA. ChIP assays revealed that TGF-β1 induced Egr1 to bind to the NOX4 promoter. Finally, Egr1 overexpression or knockdown in diabetic mice could upregulate or downregulate the expression of NOX4 and ROS, and α-SMA was also changed.

CONCLUSION

Our study provides strong evidence that Egr1 is a transcriptional activator of NOX4 in oxidative stress of DKD. Egr1 contributes to DKD by enhancing EMT, in part by targeting NOX4.

Oxytocin inhibits head and neck squamous cell carcinoma cell migration by early growth response-1 upregulation

The effect of oxytocin (OXT) on cancer invasion is controversial. Few studies have examined the effect of early growth response-1 (EGR1) on the invasion of head and neck squamous cell carcinoma (HNSCC). Here, we evaluated how EGR1 affects HNSCC cell migration through the molecular mechanism of OXT in exerting anti-invasion activity. Matrigel invasion and wound-healing assays were used to measure the in-vitro cell migration. The molecular mechanism of OXT was assessed by knockdown or overexpression of EGR1 in HNSCC cells. Three-dimensional (3-D) spheroids formation, followed by the image analysis for quantification was performed. OXT at 500 nmol/l increased mRNA and protein expression of E-cadherin without cytotoxicity. OXT upregulated mRNA and protein expression of EGR1 in 6 h. p53, phosphatase and tensin, and p21 expression was increased in an EGR1-dependent manner with OXT treatment. In addition, OXT significantly downregulated 3-D spheroids' formation according to spheroids' number and size. Our data showed that OXT downregulated HNSCC cell migration by EGR1 upregulation. OXT inhibited spheroids' formation of HNSCC cells under 3-D culture conditions.

β1-Integrin Deletion From the Lens Activates Cellular Stress Responses Leading to Apoptosis and Fibrosis

Purpose

Previous research showed that the absence of β1-integrin from the mouse lens after embryonic day (E) 13.5 (β1MLR10) leads to the perinatal apoptosis of lens epithelial cells (LECs) resulting in severe microphthalmia. This study focuses on elucidating the molecular connections between β1-integrin deletion and this phenotype.

Methods

RNA sequencing was performed to identify differentially regulated genes (DRGs) in β1MLR10 lenses at E15.5. By using bioinformatics analysis and literature searching, Egr1 (early growth response 1) was selected for further study. The activation status of certain signaling pathways (focal adhesion kinase [FAK]/Erk, TGF-β, and Akt signaling) was studied via Western blot and immunohistochemistry. Mice lacking both β1-integrin and Egr1 genes from the lenses were created (β1MLR10/Egr1-/-) to study their relationship.

Results

RNA sequencing identified 120 DRGs that include candidates involved in the cellular stress response, fibrosis, and/or apoptosis. Egr1 was investigated in detail, as it mediates cellular stress responses in various cell types, and is recognized as an upstream regulator of numerous other β1MLR10 lens DRGs. In β1MLR10 mice, Egr1 levels are elevated shortly after β1-integrin loss from the lens. Further, pErk1/2 and pAkt are elevated in β1MLR10 LECs, thus providing the potential signaling mechanism that causes Egr1 upregulation in the mutant. Indeed, deletion of Egr1 from β1MLR10 lenses partially rescues the microphthalmia phenotype.

Conclusions

β1-integrin regulates the appropriate levels of Erk1/2 and Akt phosphorylation in LECs, whereas its deficiency results in the overexpression of Egr1, culminating in reduced cell survival. These findings provide insight into the molecular mechanism underlying the microphthalmia observed in β1MLR10 mice.

p21-Activated kinase 5 affects cisplatin-induced apoptosis and proliferation in hepatocellular carcinoma cells

p21-Activated kinase 5 (PAK5) is the last identified member of the PAK family. The PAKs are highly conserved serine/threonine and effector proteins for Cdc42 and Rac and are essential in regulating cell motility and survival. Previous studies have demonstrated that PAK5 played a pivotal role in apoptosis, proliferation, cancer migration, and invasion. However, the biological function of PAK5 in hepatocellular carcinoma, as well as its underlying mechanism, still remains to be fully elucidated. In the present study, we demonstrated that PAK5 markedly inhibited cisplatin-induced apoptosis and promoted cell proliferation in hepatocellular carcinoma cells. Moreover, our results showed that overexpression of PAK5 contributed to cell cycle regulation. In order to elucidate the underlying mechanism of PAK5 on cisplatin-induced apoptosis and cell cycle regulation, we also examined the protein expressions of chk2 and p-chk2. In summary, our study investigated the role of PAK5 in cisplatin-induced cellular processes and provided evidence of its underlying mechanism.

Halofuginone - the multifaceted molecule

Halofuginone is an analog of febrifugine-an alkaloid originally isolated from the plant Dichroa febrifuga. During recent years, halofuginone has attracted much attention because of its wide range of beneficial biological activities, which encompass malaria, cancer, and fibrosis-related and autoimmune diseases. At present two modes of halofuginone actions have been described: (1) Inhibition of Smad3 phosphorylation downstream of the TGFβ signaling pathway results in inhibition of fibroblasts-to-myofibroblasts transition and fibrosis. (2) Inhibition of prolyl-tRNA synthetase (ProRS) activity in the blood stage of malaria and inhibition of Th17 cell differentiation thereby inhibiting inflammation and the autoimmune reaction by activation of the amino acid starvation and integrated stress responses. This review deals with the history and origin of this natural product, its synthesis, its known modes of action, and it's various biological activities in pre-clinical animal models and in humans.

An oncogenic kinase: putting PAK5 forward

INTRODUCTION

Overexpression of p21-activated kinase 5 (PAK5) is discovered in many tumors, probably due to its regulation in cytoskeleton, antiapoptosis and proliferation. A better understanding of the modulation mechanisms of PAK5 is needed for the development of tumor treatment where current therapeutics is inadequate.

AREAS COVERED

This review discusses the current understanding of PAK5 functions as an oncogenic kinase in tumor cellular regulation. Mechanisms of action and molecular pathways involved in cytoskeleton regulation, antiapoptosis and proliferation of tumors are discussed.

EXPERT OPINION

PAKs are serine/threonine kinases and downstream effectors for Cdc42 and Rac, the subfamilies of Rho small GTPases. PAK5 shares sequence identities in p21-GTPase-binding domain and kinase domain and is completely different in other regions compared with other PAKs. Overexpression of PAK5 has been found in several tumors, probably due to its contribution to proliferation, cytoskeleton and anti-apoptosis. Additional regulation mechanisms which are independent of Rho GTPases also indicate that PAK5 functions as a special signal molecule in cellular signaling pathways of tumor progression.

Downregulation of PAK5 inhibits glioma cell migration and invasion potentially through the PAK5-Egr1-MMP2 signaling pathway

PAK5 (p21 activated kinase 5) is upregulated in human colorectal carcinoma cells and is a known tumor promoter in carcinogenesis of the colon. Little is known regarding the mechanisms underlying the downstream targets of PAK5, and information concerning its biological significance in glioma is lacking. In this study, we investigated the effects of PAK5 on proliferation, migration, invasion, and apoptosis in human U87 and U251 glioma cells and examined the underlying molecular mechanism. We performed cell growth assays and cell cycle analysis to observe the cell proliferation. Flow cytometry analysis was performed to evaluate apoptosis, and in vitro scratch assays, cell migration assays, and gelatin zymography were performed to examine cell migration. Western blot analysis was performed to examine signal transduction in the cells. We demonstrated that suppression of PAK5 in glioma cells significantly inhibited cell migration and invasion. We also observed that suppression of PAK5 in human glioma cell lines inhibited cell growth because of G1 phase arrest. Additionally, flow cytometry and Western blot analysis indicated that PAK5 could inhibit cell apoptosis. These results suggest that the PAK5-Egr1-MMP2 signaling pathway is involved in tumor progression and may have a potential role in cancer prevention and treatment.

PAK5-Egr1-MMP2 signaling controls the migration and invasion in breast cancer cell

p21-activated kinases (PAKs) are activated by various extracellular stimuli and, in turn, activate other kinases by phosphorylating them at specific serine/threonine residues or through protein-protein interaction. As a recently identified member of the group B PAK family, the role of PAK5 in cancer is poorly understood. In this study, we investigated the effect of PAK5 on the malignant phenotype, such as proliferation, cell cycle, apoptosis, migration, and invasion. Cell growth assay and cell cycle analysis consistently showed that knockdown of PAK5 could significantly inhibit the proliferation of breast cancer cells. Wound healing assay. migration assay, and invasion assay showed that PAK5 promoted cell migration. Furthermore, in order to elucidate the underlying mechanism of PAK5 on cellular growth and migration, we examined the protein expressions of cyclin D1, p21, early growth response protein 1 (Egr1), and matrix metalloproteinase 2 (MMP2). Our work further reveals the PAK5-Egr1-MMP2 signaling pathway to be a critical regulator of cell migration and invasion. These results suggest that PAK5 may be a potential therapeutic target for breast cancer.