RhoA modulates functional and physical interaction between ROCK1 and Erk1/2 in selenite-induced apoptosis of leukaemia cells

Characterization of Anticancer Effects of the Analogs of DJ4, a Novel Selective Inhibitor of ROCK and MRCK Kinases

The Rho associated coiled-coil containing protein kinase (ROCK1 and ROCK2) and myotonic dystrophy-related Cdc-42 binding kinases (MRCKα and MRCKβ) are critical regulators of cell proliferation and cell plasticity, a process intimately involved in cancer cell migration and invasion. Previously, we reported the discovery of a novel small molecule (DJ4) selective multi-kinase inhibitor of ROCK1/2 and MRCKα/β. Herein, we further characterized the anti-proliferative and apoptotic effects of DJ4 in non-small cell lung cancer and triple-negative breast cancer cells. To further optimize the ROCK/MRCK inhibitory potency of DJ4, we generated a library of 27 analogs. Among the various structural modifications, we identified four additional active analogs with enhanced ROCK/MRCK inhibitory potency. The anti-proliferative and cell cycle inhibitory effects of the active analogs were examined in non-small cell lung cancer, breast cancer, and melanoma cell lines. The anti-proliferative effectiveness of DJ4 and the active analogs was further demonstrated against a wide array of cancer cell types using the NCI-60 human cancer cell line panel. Lastly, these new analogs were tested for anti-migratory effects in highly invasive MDA-MB-231 breast cancer cells. Together, our results demonstrate that selective inhibitors of ROCK1/2 (DJE4, DJ-Allyl) inhibited cell proliferation and induced cell cycle arrest at G2/M but were less effective in cell death induction compared with dual ROCK1/2 and MRCKα/β (DJ4 and DJ110).

Apigenin Attenuates Hippocampal Microglial Activation and Restores Cognitive Function in Methotrexate-Treated Rats: Targeting the miR-15a/ROCK-1/ERK1/2 Pathway

Microglial activation underpins the methotrexate (MTX)-induced neurotoxicity; however, the precise mechanism remains unclear. This study appraised the potential impact of apigenin (Api), a neuroprotective flavonoid, in MTX-induced neurotoxicity in rats in terms of microglial activation through targeting the miR-15a/Rho-associated protein kinase-1 (ROCK-1)/extracellular signal-regulated kinase 1/2 (ERK1/2) pathway. Male Sprague Dawley rats were randomly divided into 4 groups: Normal control (saline i.p. daily and i.v. on days 8 and 15); Api control (20 mg/kg, p.o.) daily for 30 days; MTX-alone (75 mg/kg, i.v.) on days 8 and 15, then four i.p. injections of leucovorin (LCV): 6 mg/kg after 18 h, then three doses (3 mg/kg) every 8 h post-MTX; and Api co-treated (20 mg/kg/day, p.o.) throughout the model for 30 days, with administration of MTX and LCV as in group 3. MTX administration elevated hippocampal ionized calcium-binding adaptor protein-1 (Iba-1) immunostaining, indicating microglial activation. This was accompanied by neuroinflammation, oxidative stress, and enhanced apoptosis manifested by elevated hippocampal interleukin-1β, malondialdehyde, and caspase-3, and decreased reduced glutathione levels. Concurrently, abated miR-15a expression, overexpression of its target ROCK-1, diminished downstream ERK1/2 and cAMP response element-binding protein (CREB) phosphorylation, and decreased hippocampal brain-derived neurotrophic factor (BDNF) levels were observed. Api mitigated the MTX-induced neurotoxicity by reversing the biochemical, histopathological, and behavioral derangements tested by novel object recognition and Morris water maze tests. Conclusively, Api lessens MTX-induced neuroinflammation, oxidative stress, and apoptosis and boosts cognitive function through inhibiting microglial activation via modulating the miR-15a/ROCK-1/ERK1/2/CREB/BDNF pathway. Graphical abstract showing the effects of methotrexate and apigenin co-treatment in MTX-induced neurotoxicity model. On the left, methotrexate (MTX) administration to rats resulted in hippocampal miR-15a downregulation, which triggered an enhanced expression of its target ROCK-1, consequently inhibiting the downstream ERK1/2/CREB/BDNF pathway, instigating a state of microglial activation, neuroinflammation, oxidative stress, and apoptosis. On the other hand, apigenin (Api) co-treatment restored miR-15a, inhibited ROCK-1 expression, and activated the ERK1/2/CREB/BDNF pathway, leading to diminished hippocampal microglial activation, neuroinflammation, and apoptosis, and restoration of the redox balance, along with improvement in memory and cognitive function of the MTX-treated rats.

RHOA Therapeutic Targeting in Hematological Cancers

Primarily identified as an important regulator of cytoskeletal dynamics, the small GTPase Ras homolog gene family member A (RHOA) has been implicated in the transduction of signals regulating a broad range of cellular functions such as cell survival, migration, adhesion and proliferation. Deregulated activity of RHOA has been linked to the growth, progression and metastasis of various cancer types. Recent cancer genome-wide sequencing studies have unveiled both RHOA gain and loss-of-function mutations in primary leukemia/lymphoma, suggesting that this GTPase may exert tumor-promoting or tumor-suppressive functions depending on the cellular context. Based on these observations, RHOA signaling represents an attractive therapeutic target for the development of selective anticancer strategies. In this review, we will summarize the molecular mechanisms underlying RHOA GTPase functions in immune regulation and in the development of hematological neoplasms and will discuss the current strategies aimed at modulating RHOA functions in these diseases.

Dexmedetomidine Attenuates Methotrexate-Induced Neurotoxicity and Memory Deficits in Rats through Improving Hippocampal Neurogenesis: The Role of miR-15a/ROCK-1/ERK1/2/CREB/BDNF Pathway Modulation

Methotrexate (MTX) is a widely used neurotoxic drug with broad antineoplastic and immunosuppressant spectra. However, the exact molecular mechanisms by which MTX inhibits hippocampal neurogenesis are yet unclear. Dexmedetomidine (Dex), an α2-adrenergic receptor agonist, has recently shown neuroprotective effects; however, its full mechanism is unexplored. This study investigated the potential of Dex to mitigate MTX-induced neurotoxicity and memory impairment in rats and the possible role of the miR-15a/ROCK-1/ERK1/2/CREB/BDNF pathway. Notably, no former studies have linked this pathway to MTX-induced neurotoxicity. Male Sprague Dawley rats were placed into four groups. Group 1 received saline i.p. daily and i.v. on days 8 and 15. Group 2 received Dex at 10 μg/kg/day i.p. for 30 days. Group 3 received MTX at 75 mg/kg i.v. on days 8 and 15, followed by four i.p. doses of leucovorin at 6 mg/kg after 18 h and 3 mg/kg after 26, 42, and 50 h. Group 4 received MTX and leucovorin as in group 3 and Dex daily dosages as in group 2. Bioinformatic analysis identified the association of miR-15a with ROCK-1/ERK1/2/CREB/BDNF and neurogenesis. MTX lowered hippocampal doublecortin and Ki-67, two markers of neurogenesis. This was associated with the downregulation of miR-15a, upregulation of its target ROCK-1, and reduction in the downstream ERK1/2/CREB/BDNF pathway, along with disturbed hippocampal redox state. Novel object recognition and Morris water maze tests demonstrated the MTX-induced memory deficiencies. Dex co-treatment reversed the MTX-induced behavioral, biochemical, and histological alterations in the rats. These neuroprotective actions could be partly mediated through modulating the miR-15a/ROCK-1/ERK1/2/CREB/BDNF pathway, which enhances hippocampal neurogenesis.

Selenocompounds and Sepsis-Redox Bypass Hypothesis: Part B-Selenocompounds in the Management of Early Sepsis

Significance: Endothelial barrier damage, which is in part caused by excess production of reactive oxygen, halogen and nitrogen species (ROHNS), especially peroxynitrite (ONOO^-), is a major event in early sepsis and, with leukocyte hyperactivation, part of the generalized dysregulated immune response to infection, which may even become a complex maladaptive state. Selenoenzymes have major antioxidant functions. Their synthesis is related to the need to limit deleterious oxidant redox cycling by small selenocompounds, which may be of therapeutic cytotoxic interest. Plasma selenoprotein-P is crucial for selenium transport from the liver to the tissues and for antioxidant endothelial protection, especially against ONOO^-. Above micromolar concentrations, sodium selenite (Na₂SeO₃) becomes cytotoxic, with a lower cytotoxicity threshold in activated cells, which has led to cancer research. Recent Advances: Plasma selenium (<2% of total body selenium) is mainly contained in selenoprotein-P, and concentrations decrease rapidly in the early phase of sepsis, because of increased selenoprotein-P binding and downregulation of hepatic synthesis and excretion. At low concentrations, Na₂SeO₃ acts as a selenium donor, favoring selenoprotein-P synthesis in physiology, but probably not in the acute phase of sepsis. Critical Issues: The cytotoxic effects of Na₂SeO₃ against hyperactivated leukocytes, especially the most immature forms that liberate ROHNS, may be beneficial, but they may also be harmful for activated endothelial cells. Endothelial protection against ROHNS by selenoprotein-P may reduce Na₂SeO₃ toxicity, which is increased in sepsis. Future Direction: The combination of selenoprotein-P for endothelial protection and the cytotoxic effects of Na₂SeO₃ against hyperactivated leukocytes may be a promising intervention for early sepsis. Antioxid. Redox Signal. 37, 998-1029.

Cytoplasmic Clusterin Suppresses Lung Cancer Metastasis by Inhibiting the ROCK1-ERK Axis

Simple Summary

We show that CLU, especially cytoplasmic precursor CLU, is downregulated in lung cancer and correlates with poor survival. The silencing of CLU promotes lung cancer cell migration and invasion, while the overexpression of CLU potently inhibits these phenomena. Interestingly, secretory CLU proteins are slightly decreased in lung cancer tissue and fail to exert similar anti-metastatic effects like cytoplasmic precursor CLU, demonstrating that cytoplasmic precursor CLU is the primary functional isoform of CLU, which exerts the anti-metastatic effects of lung cancer. Mechanistically, cytoplasmic precursor CLU binds ROCK1 to decrease phosphorylation of ERK1/2 by inhibiting the kinase activity of ROCK1, leading to an anti-metastatic effect in lung cancer cells. These findings reveal a novel insight into the function and regulation of cytoplasmic CLU in lung cancer, which might be a potential target for the diagnosis and treatment of metastatic lung cancer.

Abstract

Clusterin (CLU) is a heterodimeric glycoprotein that has been detected in diverse human tissues and implicated in many cellular processes. Accumulating evidence indicates that the expression of secreted CLU correlates with the progression of cancers. However, the molecular mechanisms underlying its tumor-suppressive roles are incompletely uncovered. In this study, we demonstrate that precursor CLU is widely downregulated in lung cancer tissue, in which secretory CLU proteins are slightly decreased. Impressively, overexpressing CLU potently inhibits the migration, invasion and metastasis of lung cancer cells, whereas silencing CLU promotes this behavior; however, it appears that secretory CLU fails to exert similar anti-metastatic effects. Interestingly, the cytoplasmic precursor CLU binds ROCK1 to abrogate the interaction between ROCK1 and ERK and impair ERK activity, leading to the suppression of lung cancer invasiveness. Meanwhile, the expression of CLU was remarkably diminished in lung cancer bone metastasis loci when compared with subcutaneous tumors in the mouse model and hardly detected in the bone metastasis loci of lung cancer patients when compared with the primary. These findings reveal a novel insight into the function and regulation of cytoplasmic CLU in lung cancer, which might be a potential target for the diagnosis and treatment of metastatic lung cancer.

Preclinical Evaluation of Sodium Selenite in Mice: Toxicological and Tumor Regression Studies after Striatum Implantation of Human Glioblastoma Stem Cells

Glioblastoma (GBM) is the most aggressive malignant glioma, with a very poor prognosis; as such, efforts to explore new treatments and GBM’s etiology are a priority. We previously described human GBM cells (R2J-GS) as exhibiting the properties of cancer stem cells (growing in serum-free medium and proliferating into nude mice when orthotopically grafted). Sodium selenite (SS)—an in vitro attractive agent for cancer therapy against GBM—was evaluated in R2J-GS cells. To go further, we launched a preclinical study: SS was given orally, in an escalation-dose study (2.25 to 10.125 mg/kg/day, 5 days on, 2 days off, and 5 days on), to evaluate (1) the absorption of selenium in plasma and organs (brain, kidney, liver, and lung) and (2) the SS toxicity. A 6.75 mg/kg SS dose was chosen to perform a tumor regression assay, followed by MRI, in R2J-GS cells orthotopically implanted in nude mice, as this dose was nontoxic and increased brain selenium concentration. A group receiving TMZ (5 mg/kg) was led in parallel. Although not reaching statistical significance, the group of mice treated with SS showed a slower tumor growth vs. the control group (p = 0.08). No difference was observed between the TMZ and control groups. We provide new insights of the mechanisms of SS and its possible use in chemotherapy.

miR-497-5p induces apoptosis in K562 cells by downregulating ROCK1

OBJECTIVE

To validate the role of miR-497-5p in apoptosis in K562 cells by targeting Rho-associated kinase isoform 1 (ROCK1).

METHODS

From January, 2017 to February, 2019, 57 patients with chronic myeloid leukemia (CML) treated in our hospital were included in patient group, and 50 healthy individuals were recruited as control group. miR-497-5p level in peripheral blood was quantitated using qRT-PCR. After transfecting with miR-497-5p overexpression vector and ROCK1 inhibitor, K562 cells were monitored in terms of proliferation (CCK8 assay), migration and invasion (Transwell), and apoptosis (flow cytometry). Binding loci between miR-497-5p and ROCK1 were predicted, and the targeting relationship was confirmed (dual-luciferase reporter (DLR) assay).

RESULTS

miR-497-5p was poorly expressed in CML (P < 0.05). Forced overexpression of miR-497-5p or inhibition of ROCK1 suppressed malignant processes (proliferation, proliferation, migration and invasion) in K562 cells and induced apoptosis (P < 0.05). DLR assay revealed a decreased luciferase activity after miR-497-5p binding to ROCK1 (P < 0.05).

CONCLUSION

miR-497-5p induces apoptosis in K562 cells by downregulating ROCK1.

Exosomal microRNAs from mesenchymal stem/stromal cells: Biology and applications in neuroprotection

Mesenchymal stem/stromal cells (MSCs) are extensively studied as cell-therapy agents for neurological diseases. Recent studies consider exosomes secreted by MSCs as important mediators for MSCs’ neuroprotective functions. Exosomes transfer functional molecules including proteins, lipids, metabolites, DNAs, and coding and non-coding RNAs from MSCs to their target cells. Emerging evidence shows that exosomal microRNAs (miRNAs) play a key role in the neuroprotective properties of these exosomes by targeting several genes and regulating various biological processes. Multiple exosomal miRNAs have been identified to have neuroprotective effects by promoting neurogenesis, neurite remodeling and survival, and neuroplasticity. Thus, exosomal miRNAs have significant therapeutic potential for neurological disorders such as stroke, traumatic brain injury, and neuroinflammatory or neurodegenerative diseases and disorders. This review discusses the neuroprotective effects of selected miRNAs (miR-21, miR-17-92, miR-133, miR-138, miR-124, miR-30, miR146a, and miR-29b) and explores their mechanisms of action and applications for the treatment of various neurological disease and disorders. It also provides an overview of state-of-the-art bioengineering approaches for isolating exosomes, optimizing their yield and manipulating the miRNA content of their cargo to improve their therapeutic potential.

Targeting CD276 by CAR-T cells induces regression of esophagus squamous cell carcinoma in xenograft mouse models

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CD276 is homogeneously overexpressed in ESCC and EAC.

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CD276-directed CAR-T cells demonstrate remarkable anti-tumor effects in ESCC PDX model.

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CD276-targeting CAR-T cells are successfully generated with patients T cells and show potent cytotoxicity against autologous tumor cells.

Esophageal cancer, including esophageal squamous cell carcinoma (ESCC) and esophageal adenocarcinoma (EAC), has a poor prognosis and limited therapeutic options. Chimeric antigen receptor (CAR)-T cells represent a potential ESCC treatment. In this study, we examined CD276 expression in healthy and esophageal tumor tissues and explored the tumoricidal potential of CD276-targeting CAR-T cells in ESCC. CD276 was strongly and homogenously expressed in ESCC and EAC tumor lesions but mildly in healthy tissues, representing a good target for CAR-T cell therapy. We generated CD276-directed CAR-T cells with a humanized antigen-recognizing domain and CD28 or 4–1BB co-stimulation. CD276-specific CAR-T cells efficiently killed ESCC tumor cells in an antigen-dependent manner both in vitro and in vivo. In patient-derived xenograft models, CAR-T cells induced tumor regression and extended mouse survival. In addition, CAR-T cells generated from patient T cells demonstrated potent cytotoxicity against autologous tumor cells. Our study indicates that CD276 is an attractive target for ESCC therapy, and CD276-targeting CAR-T cells are worth testing in ESCC clinical trials.

ROCK1 activation-mediated mitochondrial translocation of Drp1 and cofilin are required for arnidiol-induced mitochondrial fission and apoptosis

BACKGROUND

Arnidiol is a pentacyclic triterpene diol that has multiple pharmacological activities. However, the apoptotic activities of arnidiol in human cancer cells have not yet been explored, nor has the mechanism by which arnidiol induces apoptosis been examined in depth.

METHODS

MDA-MB-231 cells and xenografted mice were treated with arnidiol. Mitochondrial fission and apoptosis were determined by immunofluorescence, flow cytometry and related molecular biological techniques. The interaction and colocalization of cofilin and Drp1 was determined by immunoprecipitation and immunofluorescence assays.

RESULTS

Arnidiol induces mitochondrial fission and apoptosis through mitochondrial translocation of Drp1 and cofilin. Importantly, the interaction of Drp1 and cofilin in mitochondria is involved in arnidiol-induced mitochondrial fission and apoptosis. Knockdown of either Drp1 or cofilin abrogated arnidiol-induced mitochondrial translocation, interaction of Drp1 and cofilin, mitochondrial fission and apoptosis. Only dephosphorylated Drp1 (Ser637) and cofilin (Ser3) were translocated to the mitochondria. Mutants of Drp1 S637A and cofilin S3A, which mimic the dephosphorylated forms, enhanced mitochondrial fission and apoptosis induced by arnidiol, whereas mutants of Drp1 S637D and cofilin S3E, which mimic the phosphorylated forms, suppressed mitochondrial fission and apoptosis induced by arnidiol. A mechanistic study revealed that ROCK1 activation plays an important role in the arnidiol-mediated Drp1 and cofilin dephosphorylation and mitochondrial translocation, mitochondrial fission, and apoptosis.

CONCLUSIONS

Our data reveal a novel role of both Drp1 and cofilin in the regulation of mitochondrial fission and apoptosis and suggest that arnidiol could be developed as a potential agent for the treatment of human cancer.

p53 controls the switch between autophagy and apoptosis through regulation of PLSCR1 in sodium selenite-treated leukemia cells

Coordinated regulation of autophagy and apoptosis helps to enhance the antitumor effects of sodium selenite. However, the potential molecules that act as switch nodes in the crosstalk between autophagy and apoptosis is still elusive. Phospholipid scramblase 1 (PLSCR1) has been shown to regulate leukocyte differentiation, while its role in autophagy/apoptosis toggle switch remains unexplored. In this study, we showed that sodium selenite switched protective autophagy to apoptosis in p53-wild type NB4 cells without obvious caspase-8/apoptosis-inducing factor (AIF) axis activation, while induced autophagy-dependent caspase-8/AIF axis activation in p53-mutant Jurkat cells. Additionally, p53 was demonstrated as a positive regulator of PLSCR1. p53-dependent up-regulation of PLSCR1 accounted for the differential regulation of autophagy and apoptosis induced by sodium selenite. Furthermore, sodium selenite induced the release of AIF from mitochondria to cytosol with the facilitation of caspase-8 in Jurkat cells, while not in NB4 cells. The released AIF further enhanced autophagy flux through interacting with PLSCR1, which hereby resulting in the disassociation of PLSCR1 from Atg5-Atg12 complex. Our results indicate that PLSCR1 plays a critical role in p53-dependent regulation of autophagy and apoptosis in sodium selenite-treated leukemia cells. Manipulation of p53-PLSCR1 cascade might be beneficial to enhance the anti-tumor effects of sodium selenite.

Up regulation of Rho-associated coiled-coil containing kinase1 (ROCK1) is associated with genetic instability and poor prognosis in prostate cancer

BACKGROUND AND OBJECTIVES

Overexpression of the cytoskeleton-modulating kinase ROCK1 has been associated with unfavorable outcome in many cancers, but its impact in prostate cancer is largely unknown.

RESULTS

A weak ROCK1 staining was found in >90% of normal, and cancerous prostate tissues, but was generally stronger in cancer cells as compared to adjacent normal glands. In cancer, ROCK1 staining was considered weak, moderate, and strong in 22%, 53%, and 18% of cases respectively. Higher ROCK1 expression levels were associated with tumor stage, and Gleason grade, positive nodal stage, positive surgical margin, accelerated cell proliferation and early PSA recurrence in multivariable analysis. ROCK1 up regulation was associated with androgen receptor (AR) expression, TMPRSS2:ERG fusion, genomic deletions of the PTEN tumor suppressor, as well as recurrent deletions at chromosomes 3p, 5q, 6q. Strong ROCK1 staining was found in 3% of AR-negative, but in 27% of strongly AR positive cancers, in 13% of ERG-negative but in 25% of ERG positive cancers, and in 12% of PTEN normal but in 26% of PTEN deleted cancers.

CONCLUSIONS

This study identifies ROCK1 expression associated with prognosis in prostate cancer.

METHODS

We tested ROCK1 expression in 12 427 prostate cancer specimens and followed PSA recurrence after prostatectomy.

High expression of long intergenic non-coding RNA LINC00662 contributes to malignant growth of acute myeloid leukemia cells by upregulating ROCK1 via sponging microRNA-340-5p

Long non-coding RNAs (lncRNAs) have emerged as crucial regulatory factors in diverse pathological processes, especially in tumorigenesis. Accumulating evidence has demonstrated that long intergenic non-coding RNA 00662 (LINC00662) is overexpressed in multiple cancers and facilitates cancer development and progression. However, whether LINC00662 is involved in acute myeloid leukemia (AML) remains unknown. This study was aimed to explore the expression, biological function and regulatory mechanism of LINC00662 in AML. Here, we found that LINC00662 was significantly increased in AML tissues and cell lines. Knockdown of LINC00662 significantly reduced the growth of AML cells and upregulated AML cell apoptosis. In contrast, overexpression of LINC00662 promoted AML cell growth. MicroRNA-340-5p (miR-340-5p) was predicted as a target of LINC00662. Luciferase reporter assays and RNA pull-down assays confirmed that LINC00662 directly interacted with miR-340-5p. Expression of miR-340-5p was downregulated in AML and silencing of LINC00662 upregulated miR-340-5p expression in AML cells. Moreover, overexpression of miR-340-5p inhibited cell growth and increased apoptosis in AML cells. Inhibition of miR-340-5p significantly reversed the inhibitory effect of LINC00662 silencing on AML cell growth. In addition, Rho-associated protein kinase 1 (ROCK1) was verified as a target gene of miR-340-5p in AML cells. Restoration of ROCK1 expression partially reversed LINC00662 silencing or miR-340-5p overexpression-mediated inhibitory effect on AML cell growth. Overall, our results demonstrate that LINC00662 contributes to the malignant growth of AML cells by upregulating ROCK1 via sponging miR-340-5p, highlighting the important role of the LINC00662/miR-340-5p/ROCK1 axis in regulating the malignant behavior of AML cells.

Exosomes Derived From miR-133b-Modified Mesenchymal Stem Cells Promote Recovery After Spinal Cord Injury

Dysregulation of microRNAs (miRNAs) has been found in injured spinal cords after spinal cord injury (SCI). Previous studies have shown that miR-133b plays an important role in the differentiation of neurons and the outgrowth of neurites. Recently, exosomes have been used as novel biological vehicles to transfer miRNAs locally or systemically, but little is known about the effect of the delivery of exosome-mediated miRNAs on the treatment of SCI. In the present study, we observed that mesenchymal stem cells, the most common cell types known to produce exosomes, could package miR-133b into secreted exosomes. After SCI, tail vein injection of miR-133b exosomes into rats significantly improved the recovery of hindlimb function when compared to control groups. Additionally, treatment with miR-133b exosomes reduced the volume of the lesion, preserved neuronal cells, and promoted the regeneration of axons after SCI. We next observed that the expression of RhoA, a direct target of miR-133b, was decreased in the miR-133b exosome group. Moreover, we showed that miR-133b exosomes activated ERK1/2, STAT3, and CREB, which are signaling pathway proteins involved in the survival of neurons and the regeneration of axons. In summary, these findings demonstrated that systemically injecting miR-133b exosomes preserved neurons, promoted the regeneration of axons, and improved the recovery of hindlimb locomotor function following SCI, suggesting that the transfer of exosome-mediated miRNAs represents a novel therapeutic approach for the treatment of SCI.

MicroRNA-340 inhibits squamous cell carcinoma cell proliferation, migration and invasion by downregulating RhoA

BACKGROUND

MicroRNAs are reported to play an important role in tumor growth and metastasis, including squamous cell carcinoma (SCC). Accumulative evidence has revealed that dysregulated miR-340 expression contributed to the carcinogenesis and development of various cancers.

OBJECTIVE

The aim of the current study was to investigate the role and the underlying mechanism of miR-340 in SCC cell proliferation, migration and invasion.

METHODS

Quantitative real-time PCR was performed to examine the expression of miR-340 in SCC tissues and cell lines. The function of miR-340 in SCC was investigated through Cell Counting Kit-8, wound healing, transwell migration and invasion assays. Bioinformatics analysis, luciferase reporter assay, western blotting and immunohistochemical analysis were conducted to predict and confirm the target gene of miR-340.

RESULTS

In the present study, we first found that miR-340 was significantly decreased in both SCC tissues and cell lines. Moreover, ectopic expression of miR-340 remarkably attenuated SCC cell proliferation, migration and invasion, whereas inhibition of endogenous miR-340 promoted SCC cell proliferation, migration and invasion in vitro. Our subsequent bioinformatics analysis and luciferase reporter assay showed that RhoA was a novel direct target of miR-340 in SCC cells, and the knockdown of RhoA expression rescued the effects of miR-340 inhibition on SCC cell proliferation, migration and invasion. More importantly, the expression of RhoA and miR-340 was negatively correlated in SCC tissues.

CONCLUSION

Our findings demonstrate the tumor suppressor role of miR-340 in SCC by directly regulating RhoA. Therefore, restoration of miR-340 expression can be a potential therapeutic approach for SCC treatment.

Geranylgeranyl transferase 1 inhibitor GGTI‑298 enhances the anticancer effect of gefitinib

Dysregulation of epidermal growth factor receptor (EGFR) signaling is responsible for the resistance to EGFR tyrosine kinase inhibitors (TKIs), such as gefitinib and erlotinib, and is thereby associated with the progression of tumors in non‑small cell lung cancers (NSCLCs). Immunoblotting results revealed that geranylgeranyl transferase 1 inhibitor (GGTI)‑298, a geranylgeranyl transferase 1 inhibitor with potential antitumor effects, effectively inhibited the phosphorylation of EGFR and its downstream target protein kinase B (AKT). A combination of gefitinib and GGTI‑298 amplified the inhibition of the EGFR‑AKT signaling pathway. In addition, GGTI‑298 treatment produced a synergistic effect on the inhibition of proliferation as indicated by the combination index values of <1 when combined with gefitinib in the NSCLC cell lines HCC827 and A549. These synergistic effects were also observed to induce apoptosis and migration inhibition. Further mechanistic studies demonstrated that GGTI‑298 inhibited the activity of Ras homolog family member A (RhoA), and downregulation of RhoA with small interfering RNA impaired the phosphorylation of EGFR, which suggested that EGFR inhibition by GGTI‑298 may be exerted mainly through RhoA mediation. These results presented a novel, promising therapeutic strategy involving a combination of two drugs for targeting EGFR signaling in lung cancer.

Kir2.1 Interaction with Stk38 Promotes Invasion and Metastasis of Human Gastric Cancer by Enhancing MEKK2-MEK1/2-ERK1/2 Signaling

Potassium ion channels are emerging as promalignant factors involved in cancer progression. In this study, we found that invading human gastric cancer cells express high levels of inwardly rectifying potassium channel 2.1 (Kir2.1). Silencing Kir2.1 markedly reduced the invasive and metastatic capabilities as well as the epithelial-mesenchymal transition (EMT) of gastric cancer cells. The promalignant nature of Kir2.1 in gastric cancer cells was independent of potassium permeation but relied on its interaction with serine/threonine-protein kinase 38 (Stk38) to inhibit ubiquitination and degradation of mitogen-activated protein kinase kinase kinase 2 (MEKK2). Degradation of MEKK2 was mediated by small mothers against decapentaplegic-specific E3 ubiquitin protein ligase 1 (Smurf1), which resulted in activation of the MEK1/2-ERK1/2-Snail pathway in gastric cancer cells. In human gastric cancer tissues, expression was high and positively correlated with invasion depth and metastatic status of the tumors as well as poor overall patient survival. Cox regression analysis identified Kir2.1 as an independent prognostic indicator for patients with gastric cancer. Our results suggest that Kir2.1 is an important regulator of gastric cancer malignancy and acts as a novel prognostic marker and a therapeutic target for gastric cancer.Significance: Kir2.1 contributes to invasion and metastasis by a noncanonical ion permeation-independent signaling pathway and may act as a novel prognostic marker and therapeutic target for gastric cancer. Cancer Res; 78(11); 3041-53. ©2018 AACR.

RhoA and ERK signalling regulate the expression of the myogenic transcription factor Nfix

The transcription factor Nfix belongs to the nuclear factor one family and has an essential role in prenatal skeletal muscle development, where it is a master regulator of the transition from embryonic to foetal myogenesis. Recently, Nfix was shown to be involved in adult muscle regeneration and in muscular dystrophies. Here, we investigated the signalling that regulates Nfix expression, and show that JunB, a member of the AP-1 family, is an activator of Nfix, which then leads to foetal myogenesis. Moreover, we demonstrate that their expression is regulated through the RhoA/ROCK axis, which maintains embryonic myogenesis. Specifically, RhoA and ROCK repress ERK kinase activity, which promotes JunB and Nfix expression. Notably, the role of ERK in the activation of Nfix is conserved post-natally in satellite cells, which represent the canonical myogenic stem cells of adult muscle. As lack of Nfix in muscular dystrophies rescues the dystrophic phenotype, the identification of this pathway provides an opportunity to pharmacologically target Nfix in muscular dystrophies.

Regulation of RhoA GTPase and novel target proteins for ROCK

Rho GTPases play significant roles in cellular function and their activity is regulated by guanine nucleotide exchange factors (GEFs) and GTPase activating proteins (GAPs), providing activation and inactivation of these GTPases, respectively. Active GTP-bound form of RhoA activates its effector proteins while the inactive GDP-bound form of RhoA exists in a RhoA-RhoGDI (guanine nucleotide dissociation inhibitor) complex in the cytosol. In particular, IκB kinase γ IKKγ/NF-κB essential modulator (NEMO) plays a role as a GDI displacement factor (GDF) for RhoA activation through binding to RhoA-RhoGDI complex. Meanwhile, prion protein inactivates RhoA despite RhoA/RhoGDI association. Novel target proteins for Rho-associated kinase (ROCK) such as glycogen synthase kinase (GSK)-3β and IKKβ are recently discovered. Here, we elaborate on a post-translationally modified version of RhoA, phosphorylated at Tyr42 and oxidized at Cys16/20. This form of RhoA dissociates from RhoA-RhoGDI complex and activates IKKβ on IKKγ/NEMO, thus providing possibly a critical role for tumourigenesis.

Selenite inhibits glutamine metabolism and induces apoptosis by regulating GLS1 protein degradation via APC/C-CDH1 pathway in colorectal cancer cells

Glutaminolysis is important for metabolism and biosynthesis of cancer cells, and GLS is essential in the process. Selenite is widely regarded as a chemopreventive agent against cancer risk. Emerging evidence suggests that it also has chemotherapeutic potential in various cancer types, but the mechanism remains elusive. We demonstrate for the first time that supranutritional dose of selenite suppresses glutaminolysis by promoting GLS1 protein degradation and apoptosis. Mechanistically, selenite promotes association of APC/C-CDH1 with GLS1 and leads to GLS1 degradation by ubiquitination, this process is related to induction of PTEN expression. In addition, GLS1 expression is increased in human colorectal cancer tissues compared with normal mucosae. Our data provide a novel mechanistic explanation for the anti-cancer effect of selenite from a perspective of cell metabolism. Moreover, our results indicate that glutaminolysis especially GLS1 could be an attractive therapeutic target in colorectal cancer.

MYBPH inhibits vascular smooth muscle cell migration and attenuates neointimal hyperplasia in a rat carotid balloon-injury model

Vascular smooth muscle cell (VSMC) migration is implicated in restenosis. Myosin binding protein H (MYBPH) is capable of reducing cell motility and metastasis. In this study, we sought to determine whether MYBPH is involved in VSMC migration and neointima formation in response to vascular injury. To determine the expression of MYBPH in injured artery, we used a standard rat carotid artery balloon-injury model. In vivo studies have demonstrated that MYBPH is upregulated after vascular injury. VSMCs treated with platelet-derived growth factor (PDGF)-BB displayed increased MYBPH mRNA and protein levels. PDGF-induced VSMC migration was inhibited by adenovirus-mediated expression of MYBPH whereas it was enhanced by small interfering RNA knockdown of MYBPH. The activation of ROCK1 was repressed by MYBPH. Luminal delivery of MYBPH adenovirus to carotid arteries decreased neointimal hyperplasia in vivo. MYBPH may, therefore, serve as a novel therapeutic target for postangioplasty restenosis.

Phosphodiesterase 5 Inhibition Limits Doxorubicin-induced Heart Failure by Attenuating Protein Kinase G Iα Oxidation

Phosphodiesterase 5 (PDE5) inhibitors limit myocardial injury caused by stresses, including doxorubicin chemotherapy. cGMP binding to PKG Iα attenuates oxidant-induced disulfide formation. Because PDE5 inhibition elevates cGMP and protects from doxorubicin-induced injury, we reasoned that this may be because it limits PKG Iα disulfide formation. To investigate the role of PKG Iα disulfide dimerization in the development of apoptosis, doxorubicin-induced cardiomyopathy was compared in male wild type (WT) or disulfide-resistant C42S PKG Iα knock-in (KI) mice. Echocardiography showed that doxorubicin treatment caused loss of myocardial tissue and depressed left ventricular function in WT mice. Doxorubicin also reduced pro-survival signaling and increased apoptosis in WT hearts. In contrast, KI mice were markedly resistant to the dysfunction induced by doxorubicin in WTs. In follow-on experiments the influence of the PDE5 inhibitor tadalafil on the development of doxorubicin-induced cardiomyopathy in WT and KI mice was investigated. In WT mice, co-administration of tadalafil with doxorubicin reduced PKG Iα oxidation caused by doxorubicin and also protected against cardiac injury and loss of function. KI mice were again innately resistant to doxorubicin-induced cardiotoxicity, and therefore tadalafil afforded no additional protection. Doxorubicin decreased phosphorylation of RhoA (Ser-188), stimulating its GTPase activity to activate Rho-associated protein kinase (ROCK) in WTs. These pro-apoptotic events were absent in KI mice and were attenuated in WTs co-administered tadalafil. PKG Iα disulfide formation triggers cardiac injury, and this initiation of maladaptive signaling can be blocked by pharmacological therapies that elevate cGMP, which binds kinase to limit its oxidation.

EM23, A Natural Sesquiterpene Lactone from Elephantopus mollis, Induces Apoptosis in Human Myeloid Leukemia Cells through Thioredoxin- and Reactive Oxygen Species-Mediated Signaling Pathways

Elephantopus mollis (EM) is a traditional herbal medicine with multiple pharmacological activities. However, the efficacy of EM in treating human leukemia is currently unknown. In the current study, we report that EM23, a natural sesquiterpene lactone isolated from EM, inhibits the proliferation of human chronic myeloid leukemia (CML) K562 cells and acute myeloid leukemia (AML) HL-60 cells by inducing apoptosis. Translocation of membrane-associated phospholipid phosphatidylserines, changes in cell morphology, activation of caspases, and cleavage of PARP were concomitant with this inhibition. The involvement of the mitochondrial pathway in EM23-mediated apoptosis was suggested by observed disruptions in mitochondrial membrane potential. Mechanistic studies indicated that EM23 caused a marked increase in the level of reactive oxygen species (ROS). Pretreatment with N-acetyl-L-cysteine, a ROS scavenger, almost fully reversed EM23-mediated apoptosis. In EM23-treated cells, the expression levels of thioredoxin (Trx) and thioredoxinreductase (TrxR), two components of the Trx system involved in maintaining cellular redox homeostasis, were significantly down-regulated. Concomitantly, Trx regulated the activation of apoptosis signal-regulating kinase 1 (ASK1) and its downstream regulatory targets, the p38, JNK, and ERK MAPKs. EM23-mediated activation of ASK1/MAPKs was significantly inhibited in the presence of NAC. Furthermore, tumor necrosis factor alpha (TNF-α)-mediated activation of nuclear factor-κB (NF-κB) was suppressed by EM23, as suggested by the observed blockage of p65 nuclear translocation, phosphorylation, and reversion of IκBα degradation following EM23 treatment. Taken together, these results provide important insights into the anticancer activities of the EM component EM23 against human CML K562 cells and AML HL-60 cells.

Novel Insights into the Roles of Rho Kinase in Cancer

Rho-associated coiled-coil kinase (ROCK) is a major downstream effector of the small GTPase RhoA. The ROCK family, consisting of ROCK1 and ROCK2, plays a central role in the organization of the actin cytoskeleton, and is involved in a wide range of fundamental cellular functions such as contraction, adhesion, migration, proliferation, and apoptosis. Since the discovery of effective inhibitors such as fasudil and Y27632, the biological roles of ROCK have been extensively explored in numerous diseases, including cancer. Accumulating evidence supports the concept that ROCK plays important roles in tumor development and progression through regulating many key cellular functions associated with malignancy, including tumorigenicity, tumor growth, metastasis, angiogenesis, tumor cell apoptosis/survival and chemoresistance as well. This review focuses on the new advances of the most recent 5 years from the studies on the roles of ROCK in cancer development and progression; the discussion is mainly focused on the potential value of ROCK inhibitors in cancer therapy.

miR-125a-3p and miR-483-5p promote adipogenesis via suppressing the RhoA/ROCK1/ERK1/2 pathway in multiple symmetric lipomatosis

Multiple symmetric lipomatosis (MSL) is a rare disease characterized by symmetric and abnormal distribution of subcutaneous adipose tissue (SAT); however, the etiology is largely unknown. We report here that miR-125a-3p and miR-483-5p are upregulated in the SAT of MSL patients, promoting adipogenesis through suppressing the RhoA/ROCK1/ERK1/2 pathway. TaqMan microRNA (miR) array analysis revealed that 18 miRs were upregulated in the SAT of MSL patients. Transfection of human adipose-derived mesenchymal stem cells (hADSCs) with the individual agomirs of these 18 miRs showed that miR-125a-3p and miR-483-5p significantly promoted adipogenesis. A dual-luciferase assay showed that RhoA and ERK1 were the targets of miR-125a-3p and miR-483-5p, respectively. Moreover, transfection of hADSCs with mimics of miR-125a-3p and miR-483-5p resulted in a pronounced decrease of ERK1/2 phosphorylation in the nucleus; conversely, transfection of hADSCs with inhibitors of miR-125a-3p and miR-483-5p led to a significant increase of ERK1/2 phosphorylation in the nucleus. Most importantly, we found that miR-125a-3p and miR-483-5p promoted de novo adipose tissue formation in nude mice. These results demonstrated that miR-125a-3p and miR-483-5p coordinately promoted adipogenesis through suppressing the RhoA/ROCK1/ERK1/2 pathway. Our findings may provide novel strategies for the management and treatment of MSL or obesity.

Families of microRNAs Expressed in Clusters Regulate Cell Signaling in Cervical Cancer

Tumor cells have developed advantages to acquire hallmarks of cancer like apoptosis resistance, increased proliferation, migration, and invasion through cell signaling pathway misregulation. The sequential activation of genes in a pathway is regulated by miRNAs. Loss or gain of miRNA expression could activate or repress a particular cell axis. It is well known that aberrant miRNA expression is well recognized as an important step in the development of cancer. Individual miRNA expression is reported without considering that miRNAs are grouped in clusters and may have similar functions, such as the case of clusters with anti-oncomiRs (23b~27b~24-1, miR-29a~29b-1, miR-29b-2~29c, miR-99a~125b-2, miR-99b~125a, miR-100~125b-1, miR-199a-2~214, and miR-302s) or oncomiRs activity (miR-1-1~133a-2, miR-1-2~133a-1, miR-133b~206, miR-17~92, miR-106a~363, miR183~96~182, miR-181a-1~181b-1, and miR-181a-2~181b-2), which regulated mitogen-activated protein kinases (MAPK), phosphatidylinositol-4,5-bisphosphate 3-kinase (PI3K), NOTCH, proteasome-culling rings, and apoptosis cell signaling. In this work we point out the pathways regulated by families of miRNAs grouped in 20 clusters involved in cervical cancer. Reviewing how miRNA families expressed in cluster-regulated cell path signaling will increase the knowledge of cervical cancer progression, providing important information for therapeutic, diagnostic, and prognostic methodology design.

RhoA/mDia-1/profilin-1 signaling targets microvascular endothelial dysfunction in diabetic retinopathy

BACKGROUND

Diabetic retinopathy (DR) is a major cause of blindness in the working-age populations of developed countries, and effective treatments and prevention measures have long been the foci of study. Patients with DR invariably demonstrate impairments of the retinal microvascular endothelium. Many observational and preclinical studies have shown that angiogenesis and apoptosis play crucial roles in the pathogenesis of DR. Increasing evidence suggests that in DR, the small guanosine-5'-triphosphate-binding protein RhoA activates its downstream targets mammalian Diaphanous homolog 1 (mDia-1) and profilin-1, thus affecting important cellular functions, including cell morphology, motility, secretion, proliferation, and gene expression. However, the specific underlying mechanism of disease remains unclear.

CONCLUSION

This review focuses on the RhoA/mDia-1/profilin-1 signaling pathway that specifically triggers endothelial dysfunction in diabetic patients. Recently, RhoA and profilin-1 signaling has attracted a great deal of attention in the context of diabetes-related research. However, the precise molecular mechanism by which the RhoA/mDia-1/profilin-1 pathway is involved in progression of microvascular endothelial dysfunction (MVED) during DR has not been determined. This review briefly describes each feature of the cascade before exploring the most recent findings on how the pathway may trigger endothelial dysfunction in DR. When the underlying mechanisms are understood, novel therapies seeking to restore the endothelial homeostasis comprised in DR will become possible.

ROS inhibit autophagy by downregulating ULK1 mediated by the phosphorylation of p53 in selenite-treated NB4 cells

Reactive oxygen species (ROS) have an important role in regulating various cellular processes. Our previous study confirmed that selenite, an anti-tumour agent, triggered apoptosis through the production of ROS in multiple types of cancer cells. In this study, we discovered that ROS also inhibited protective autophagy by decreasing the expression of ULK1, an initiator of autophagy, in selenite-treated NB4 cells. Further experiments demonstrated that p-p53 (S392), a phosphorylation event promoted by p70S6K, bound to the promoter of ULK1 and modulated its expression. Experiments in a mouse tumour model with NB4 cells provided in vivo confirmation of the alterations in the p70S6K/p53/ULK1 axis. Collectively, our results show that ROS inhibited autophagy by downregulating the p70S6K/p53/ULK1 axis in selenite-treated NB4 cells.

RhoV mediates apoptosis of RAW264.7 macrophages caused by osteoclast differentiation

Macrophages, a type of immune cell, are the precursors of osteoclasts, and have important roles in bone remodeling and the immune system. In the present study, the RAW264.7 cell line was used as a macrophage model in order to study the macrophage changes during osteoclastogenesis. Receptor activator of nuclear factor κB ligand (RANKL) and macrophage colony‑stimulating factor (M‑CSF) induce the formation of osteoclasts from several precursor cells. Observation of RAW264.7 macrophage osteoclastogenesis under the induction of RANKL and M‑CSF revealed that except the few RAW264.7 macrophages that were differentiated into osteoclasts, almost all undifferentiated RAW264.7 macrophages underwent apoptosis. BRL‑3A cells have no differentiation ability, and RANKL and M‑CSF treatments did not induce BRL‑3A cell apoptosis. When osteoprotegerin (OPG) was used to completely inhibit the differentiation of RAW264.7 macrophages to osteoclasts, apoptosis did not occur amongst the RAW264.7 macrophages despite the action of RANKL and M‑CSF. Rac1, RhoA and RhoV are apoptosis‑associated genes in the Rho guanosine triphosphate (GTP)ase family. Their expression levels were detected using quantitative polymerase chain reaction (qPCR). During the process of osteoclast differentiation, the mRNA expression of RhoV was significantly upregulated, while apoptosis occurred in a large proportion of macrophages. However, when macrophage apoptosis was inhibited by OPG, RhoV expression was significantly downregulated. Conversely, Rac1 and RhoA expression did not vary in correspondence with the apoptotic rate of the RAW264.7 macrophages. In conclusion, differentiation of RAW264.7 macrophages into osteoclasts resulted in their apoptosis. OPG inhibited RAW264.7 macrophage differentiation into osteoclasts, and thereby inhibited the apoptosis of RAW264.7 macrophages. RhoV mediated the apoptosis of RAW264.7 macrophages during osteoclast differentiation.

Survivin-2B promotes autophagy by accumulating IKK alpha in the nucleus of selenite-treated NB4 cells

Survivin-2B, a known splice variant of survivin, has been reported to promote cell death in some cancer cells, although it keeps prosurvival function in others, and the mechanisms are unclear. In this report, we discovered that selenite, an antitumor agent, switched protective autophagy to apoptosis in NB4 cells. In this process, the level of survivin-2B was decreased and the interaction between IKK alpha and survivin-2B in the nucleus was attenuated, which further led to the decrease of nuclear IKK alpha. As a result, P73, a known transcript factor of UVRAG, was downregulated. Therefore, the expression of UVRAG, one of the initiators of autophagy, was inhibited. The regulatory status of survivin-2B was also proved in NB4 cells after different chemicals' exposure and in other tumor cell lines (Jurkat, HCT116). Finally, experiments in vivo confirmed that the alterations of survivin-2B, IKK alpha, P73 and UVRAG were the same as that in vitro. Taken together, survivin-2B promoted autophagy and further regulated cell death by accumulating and stabilizing IKK alpha in the nucleus.

Combined microRNA-340 and ROCK1 mRNA profiling predicts tumor progression and prognosis in pediatric osteosarcoma

To investigate the association of combined microRNA-340 (miR-340) and ROCK1 mRNA profiling with clinicopathologic features and prognosis in pediatric patients with osteosarcoma. Quantitative real-time reverse transcriptase-polymerase chain reaction analysis was performed to detect expression levels of miR-340 and ROCK1 mRNA in cancerous and noncancerous bone tissues from 92 children treated for primary osteosarcomas. Compared with noncancerous bone tissues, the expression levels of miR-340 and ROCK1 mRNA were, respectively, downregulated and upregulated in osteosarcoma tissues (both p < 0.001), which was consistent with the results of in situ hybridization and immunohistochemistry analysis. The downregulation of miR-340 was negatively correlated with the upregulation of ROCK1 mRNA in osteosarcoma tissues (r = −0.78, p = 0.001). In addition, the combined miR-340 downregulation and ROCK1 upregulation (miR-340-low/ROCK1-high) occurred more frequently in osteosarcoma tissues with positive metastasis (p < 0.001) and poor response to pre-operative chemotherapy (p = 0.002). Moreover, miR-340-low/ROCK1-high expression was significantly associated with both shortest overall survival (p < 0.001) and progression-free survival (p < 0.001). Multivariate analysis further confirmed that miR-340-low/ROCK1-high expression was an independent prognostic factor of unfavorable survival in pediatric osteosarcoma (for overall survival: p = 0.006, for progression-free survival: p = 0.008). Our data offer convincing evidence, for the first time, that the combined miR-340 downregulation and ROCK1 upregulation may be linked to tumor progression and adverse prognosis in pediatric osteosarcoma.

The ROS/JNK/ATF2 pathway mediates selenite-induced leukemia NB4 cell cycle arrest and apoptosis in vitro and in vivo

It has previously been shown that selenite can act as an antitumor agent and inhibit cancer cell growth, although the mechanism responsible for this effect is not well understood. In this study, we have shown that selenite can induce cell cycle arrest and apoptosis in NB4 cells. Selenite treatment of these cells also inhibited the JNK/ATF2 axis. Further experiments demonstrated that selenite-induced production of reactive oxygen species (ROS) worked as an upstream of the JNK/ATF2 axis, cell cycle arrest and apoptosis. Inactivation of ATF2 resulted in decreased affinity of this transcription factor for the promoters of cyclin A, cyclin D3 and CDK4, which led to the arrest of the NB4 cells in the G0/G1 phase. Finally, in vivo experiments confirmed the antitumor activity of selenite and the mechanisms that were described in vitro. Taken together, our results indicate that selenite-induced ROS arrest NB4 cells at G0/G1 phase through inhibiting the JNK/ATF2 axis in vitro and in vivo.

Friend or foe? The current epidemiologic evidence on selenium and human cancer risk

Scientific opinion on the relationship between selenium and the risk of cancer has undergone radical change over the years, with selenium first viewed as a possible carcinogen in the 1940s then as a possible cancer preventive agent in the 1960s-2000s. More recently, randomized controlled trials have found no effect on cancer risk but suggest possible low-dose dermatologic and endocrine toxicity, and animal studies indicate both carcinogenic and cancer-preventive effects. A growing body of evidence from human and laboratory studies indicates dramatically different biological effects of the various inorganic and organic chemical forms of selenium, which may explain apparent inconsistencies across studies. These chemical form-specific effects also have important implications for exposure and health risk assessment. Overall, available epidemiologic evidence suggests no cancer preventive effect of increased selenium intake in healthy individuals and possible increased risk of other diseases and disorders.