Crosstalk between Raf/MEK/ERK and PI3K/AKT in suppression of Bax conformational change by Grp75 under glucose deprivation conditions

Prenatal to preimplantation genetic diagnosis of a novel compound heterozygous mutation in HSPA9 associated with Even-Plus syndrome

BACKGROUND

Heat shock protein family A member 9 (HSPA9) prevents unfolded and dysfunctional protein accumulation, with genetic variants known to be pathogenic. Here, we determined the genetic cause of Even-Plus syndrome (OMIM: 616854) in a Chinese family.

METHODS

We collected samples from two affected and two normal individuals. Whole-exome sequencing was performed to identify their genetic profiles. Potential variants were validated using Sanger sequencing. Assisted reproduction with mutation-free embryos successfully blocked the transmission of mutations.

RESULTS

We identified novel inherited pathogenic complex heterozygous variations in the HSPA9 gene in the two affected fetuses. Three-dimensional spatial simulation of the HSPA9 protein after prediction of the mutated RNA splicing pattern abolished part of the substrate-binding domain of the protein. According to ACMG guidelines, c. 1822-1G>A and c. 1411-3T>G were classified as pathogenic and likely pathogenic, respectively. Mutation-free embryos were selected for transplantation and reconfirmed to possess no mutations. A healthy daughter was successfully born into the family.

CONCLUSIONS

This study is the first to report complex heterozygous variations in the HSPA9 gene that influence alternative splicing in early pregnancy. Our findings expand on the mutational spectrum leading to Even-Plus syndrome and provide a basis for genetic counseling and future embryonic studies.

Restoration of p53 functions by suppression of mortalin-p53 sequestration: an emerging target in cancer therapy

Functional inactivation of wild-type p53 is a major trait of cancerous cells. In many cases, such inactivation occurs by either TP53 gene mutations or due to overexpression of p53 binding partners. This review focuses on an overexpressed p53 binding partner called mortalin, a mitochondrial heat shock protein that sequesters both wild-type and mutant p53 in malignant cells due to changes in subcellular localization. Clinical evidence suggests a drastic depletion of the overall survival time of cancer patients with high mortalin expression. Therefore, mortalin-p53 sequestration inhibitors could be game changers in improving overall survival rates. This review explores the consequences of mortalin overexpression and challenges, status and strategies for accelerating drug discovery to suppress mortalin-p53 sequestration.

HSP70 Family in Cancer: Signaling Mechanisms and Therapeutic Advances

The 70 kDa heat shock proteins (HSP70s) are a group of highly conserved and inducible heat shock proteins. One of the main functions of HSP70s is to act as molecular chaperones that are involved in a large variety of cellular protein folding and remodeling processes. HSP70s are found to be over-expressed and may serve as prognostic markers in many types of cancers. HSP70s are also involved in most of the molecular processes of cancer hallmarks as well as the growth and survival of cancer cells. In fact, many effects of HSP70s on cancer cells are not only related to their chaperone activities but rather to their roles in regulating cancer cell signaling. Therefore, a number of drugs directly or indirectly targeting HSP70s, and their co-chaperones have been developed aiming to treat cancer. In this review, we summarized HSP70-related cancer signaling pathways and corresponding key proteins regulated by the family of HSP70s. In addition, we also summarized various treatment approaches and progress of anti-tumor therapy based on targeting HSP70 family proteins.

Mortalin: Protein partners, biological impacts, pathological roles, and therapeutic opportunities

Mortalin (GRP75, HSPA9A), a heat shock protein (HSP), regulates a wide range of cellular processes, including cell survival, growth, and metabolism. The regulatory functions of mortalin are mediated through a diverse set of protein partners associated with different cellular compartments, which allows mortalin to perform critical functions under physiological conditions, including mitochondrial protein quality control. However, alteration of mortalin's activities, its abnormal subcellular compartmentalization, and its protein partners turn mortalin into a disease-driving protein in different pathological conditions, including cancers. Here, mortalin's contributions to tumorigenic pathways are explained. Pathology information based on mortalin's RNA expression extracted from The Cancer Genome Atlas (TCGA) transcriptomic database indicates that mortalin has an independent prognostic value in common tumors, including lung, breast, and colorectal cancer (CRC). Subsequently, the binding partners of mortalin reported in different cellular models, from yeast to mammalian cells, and its regulation by post-translational modifications are discussed. Finally, we focus on colorectal cancer and discuss how mortalin and its tumorigenic downstream protein targets are regulated by a ubiquitin-like protein through the 26S proteasomal degradation machinery. A broader understanding of the function of mortalin and its positive and negative regulation in the formation and progression of human diseases, particularly cancer, is essential for developing new strategies to treat a diverse set of human diseases critically associated with dysregulated mortalin.

Isolation and anticancer activity evaluation of rare Bisaryl anthraquinone antibiotics from novel Streptomyces sp. strain of NW Himalayan region

Biosynthesis of bisaryl preanthraquinone antibiotics by various microorganisms differs in monomeric subunits as well as their dimerization positions leading to different configurations. The present study relates to the production of rare bisaryl anthraquinone antibiotics by a new Streptomyces strain isolated from Shivalik region of NW Himalayas. In vitro anticancer and anti-migratory effects of Setomimycin (9,9' bisanthraquinone antibiotic) was seen with a significant reduction in the expression of both MEK as well as ERK pathways in a dose dependent manner at 6.5 μM & 8 μM concentration in HCT-116 and 5.5 μM & 7 μM concentration in MCF-7 cells. In vivo studies in aggressive orthotopic mouse mammary carcinoma model (4T1) demonstrated about 76% reduction of primary tumor weight and 90.5% reduction in the tumor volume within two weeks. In vivo pharmacokinetics study of setomimycin revealed that it can be rapidly absorbed with an adequate plasma exposure and half-life which can be linked to its in vivo efficacy.

Why is Mortalin a Potential Therapeutic Target for Cancer?

Cancer is one of the leading causes of death worldwide, accounting for nearly 10 million deaths in 2020. Therefore, cancer therapy is a priority research field to explore the biology of the disease and identify novel targets for the development of better treatment strategies. Mortalin is a member of the heat shock 70 kDa protein family. It is enriched in several types of cancer and contributes to carcinogenesis in various ways, including inactivation of the tumor suppressor p53, deregulation of apoptosis, induction of epithelial–mesenchymal transition, and enhancement of cancer stemness. It has been studied extensively as a therapeutic target for cancer treatment, and several types of anti-mortalin molecules have been discovered that effectively suppress the tumor cell growth. In this review, we 1) provide a comprehensive sketch of the role of mortalin in tumor biology; 2) discuss various anti-mortalin molecules, including natural compounds, synthetic small molecules, peptides, antibodies, and nucleic acids, that have shown potential for cancer treatment in laboratory studies; and 3) provide future perspectives in cancer treatment.

MORTALIN-Ca2+ axis drives innate rituximab resistance in diffuse large B-cell lymphoma

Diffuse large B-cell lymphoma (DLBCL) is the most common subtype of non-Hodgkin's lymphoma, with the combination of rituximab and chemotherapy being the standard treatment for it. Although rituximab monotherapy has a remarkable response rate, drug resistance with unclear mechanisms and lack of effective second-line therapy limit the survival benefits of patients with lymphoma. Here, we report that MORTALIN is highly expressed and correlates with resistance to rituximab-based therapy and poor survival in patients with DLBCL. Mechanistically, gain- and loss-of-function experiments revealed that the voltage-dependent anion channel 1-binding protein, MORTALIN, regulated Ca²⁺ release from the endoplasmic reticulum through mitochondria-associated membrane, facilitating AP1-mediated cell proliferation and YY-1-mediated downregulation of FAS in DLBCL cells. These dual mechanisms contribute to rituximab resistance. In mouse models, genetic depletion of MORTALIN markedly increased the antitumor activity of rituximab. We shed mechanistic light on MORTALIN-Ca²⁺-CaMKII-AP1-mediated proliferation and MORTALIN-Ca²⁺-CaMKII-inhibited death receptor in DLBCL, leading to rituximab resistance, and propose MORTALIN as a novel target for the treatment of DLBCL.

Mortalin/glucose-regulated protein 75 promotes the cisplatin-resistance of gastric cancer via regulating anti-oxidation/apoptosis and metabolic reprogramming

Platinum drug treatment is one of the most predominant chemotherapeutic strategies for patients with gastric cancer (GC). However, the therapeutic effect is less than satisfactory, largely due to the acquired resistance to platinum drugs. Therefore, a better understanding of the underlying mechanisms can greatly improve the therapeutic efficacy of GC. In this study, we aimed to investigate the chemo-resistance related functions/mechanisms and clinical significance of glucose-regulated protein 75 (GRP75) in GC. Here, our data showed that compared with SGC7901 cells, the expression of GRP75 was markedly higher in cisplatin-resistance cells (SGC7901^CR). Knockdown of GRP75 abolished the maintenance of mitochondrial membrane potential (MMP) and inhibited the nuclear factor erythroid-2-related factor 2 (NRF2), phosphatidylinositol 3 kinase/protein kinase B (PI3K/AKT), hypoxia-inducible factor 1α (HIF-1α), and c-myc, which resulted in blocking the activation of their downstream targets. These processes attenuated the anti-oxidation/apoptosis abilities and altered the metabolic reprogramming in SGC7901^CR cells, leading to re-sensitizing these cells to cisplatin. However, overexpression of GRP75 in SGC7901 cells caused the opposite effects. A xenografts model confirmed the abovementioned results. In GC patients receiving platinum chemotherapy and a meta-analysis, a high level of GRP75 was positively associated with aggressive characteristics and poor prognosis including but not limited to gastrointestinal cancers, and was an independent predictor for overall survival. Collectively, our study indicated that GRP75 was involved in the cisplatin-resistance of GC and that GRP75 could be a potential therapeutic target for restoring the drug response in platinum-resistance cells and a useful additive prognostic tool in guiding clinical management of GC patients.

Blocking of Transient Receptor Potential Vanilloid 1 (TRPV1) promotes terminal mitophagy in multiple myeloma, disturbing calcium homeostasis and targeting ubiquitin pathway and bortezomib-induced unfolded protein response

Background

Chemoresistance remains a major treatment obstacle in multiple myeloma (MM). Novel new therapies are thus in need. Transient Receptor Potential Vanilloid type 1 (TRPV1) is a calcium-permeable ion channel that has been demonstrated to be expressed in solid tumors. Calcium channels have been shown to be involved in the regulation of cell proliferation, chemoresistance, migration and invasion. The aim of the current study was to evaluate its possible role in MM.

Methods

Pharmacological inhibitor was used to evaluate the role of TRPV1 in MM cell lines and primary MM cells. Flow cytometry, molecular analysis, fluorescent microscopy, proteomic analysis and xenograft in vivo model of MM with BM involvement were employed to assess the effect of TRPV1 inhibition and decipher its unique mechanism of action in MM.

Results

TRPV1 was found to be expressed by MM cell lines and primary MM cells. TRPV1 inhibition using the antagonist AMG9810-induced MM cell apoptosis and synergized with bortezomib, overcoming both CXCR4-dependent stroma-mediated and acquired resistance. In accordance, AMG9810 suppressed the expression and activation of CXCR4 in MM cells. TRPV1 inhibition increased mitochondrial calcium levels with subsequent mitochondrial ROS accumulation and depolarization. These effects were reversed by calcium chelation, suggesting the role of calcium perturbations in oxidative stress and mitochondrial destabilization. Furthermore, AMG9810 abolished bortezomib-induced accumulation of mitochondrial HSP70 and suppressed protective mitochondrial unfolded protein response. Proteomics revealed unique molecular signature related to the modification of ubiquitin signaling pathway. Consequently, 38 proteins related to the ubiquitylation machinery were downregulated upon combined bortezomib/AMG9810 treatment. Concomitantly, AMG9810 abolished bortezomib-induced ubiquitination of cytosolic and mitochondrial proteins. Furthermore, bortezomib/AMG9810 treatment induced mitochondrial accumulation of PINK1, significantly reduced the mitochondrial mass and promoted mitochondrial-lysosomal fusion, indicating massive mitophagy. Finally, in a recently developed xenograft model of systemic MM with BM involvement, bortezomib/AMG9810 treatment effectively reduced tumor burden in the BM of MM-bearing mice.

Conclusions

Altogether, our results unravel the mechanism mediating the strong synergistic anti-MM activity of bortezomib in combination with TRPV1 inhibition which may be translated into the clinic.

Epigallocatechin-3-Gallate and PEDF 335 Peptide, 67LR Activators, Attenuate Vasogenic Edema, and Astroglial Degeneration Following Status Epilepticus

Non-integrin 67-kDa laminin receptor (67LR) is involved in cell adherence to the basement membrane, and it regulates the interactions between laminin and other receptors. The dysfunction of 67LR leads to serum extravasation via blood-brain barrier (BBB) disruption. Polyphenol (–)-epigallocatechin-3-O-gallate (EGCG) and pigment epithelium-derived factor (PEDF) bind to 67LR and inhibit neovascularization. Therefore, in the present study, we investigated the effects of EGCG and NU335, a PEDF-derive peptide, on BBB integrity and their possible underlying mechanisms against vasogenic edema formation induced by status epilepticus (SE, a prolonged seizure activity). Following SE, both EGCG and NU335 attenuated serum extravasation and astroglial degeneration in the rat piriform cortex (PC). Both EGCG and NU335 reversely regulated phosphatidylinositol 3 kinase (PI3K)/AKT–eNOS (endothelial nitric oxide synthase) mediated BBB permeability and aquaporin 4 (AQP4) expression in endothelial cells and astrocytes through the p38 mitogen-activated protein kinase (p38 MAPK) and extracellular signal-regulated kinase 1/2 (ERK1/2) signaling pathways, respectively. Furthermore, EGCG and NU335 decreased p47Phox (a nicotinamide adenine dinucleotide phosphate oxidase subunit) expression in astrocytes under physiological and post-SE conditions. Therefore, we suggest that EGCG and PEDF derivatives may activate 67LR and its downstream effectors, and they may be considerable anti-vasogenic edema agents.

Role of Spinal Cord Akt-mTOR Signaling Pathways in Postoperative Hyperalgesia Induced by Plantar Incision in Mice

Poor postoperative pain (POP) control increases perioperative morbidity, prolongs hospitalization days, and causes chronic pain. However, the specific mechanism(s) underlying POP is unclear and the identification of optimal perioperative treatment remains elusive. Akt and mammalian target of rapamycin (mTOR) are expressed in the spinal cord, dorsal root ganglion, and sensory axons. In this study, we explored the role of Akt and mTOR in pain-related behaviors induced by plantar incision in mice. Plantar incision activated spinal Akt and mTOR in a dose-dependent manner. Pre-treatment with Akt inhibitors intrathecally prevented the activation of mTOR dose-dependently. In addition, blocking the Akt-mTOR signaling cascade attenuated pain-related behaviors and spinal Fos protein expression induced by plantar incision. Our observations demonstrate that Akt-mTOR might be a potential therapeutic target for the treatment of POP.

Blockade of 67-kDa Laminin Receptor Facilitates AQP4 Down-Regulation and BBB Disruption via ERK1/2-and p38 MAPK-Mediated PI3K/AKT Activations

Recently, we have reported that dysfunctions of 67-kDa laminin receptor (67LR) induced by status epilepticus (SE, a prolonged seizure activity) and 67LR neutralization are involved in vasogenic edema formation, accompanied by the reduced aquaporin 4 (AQP4, an astroglial specific water channel) expression in the rat piriform cortex (PC). In the present study, we found that the blockade of 67LR activated p38 mitogen-activated protein kinase (p38 MAPK) and extracellular signal-regulated kinase 1/2 (ERK1/2) signaling pathways, which enhanced phosphatidylinositol 3 kinase (PI3K)/AKT phosphorylations in endothelial cells and astrocytes, respectively. 67LR-p38 MAPK-PI3K-AKT activation in endothelial cells increased vascular permeability. In contrast, 67LR-ERK1/2-PI3K-AKT signaling pathways in astrocytes regulated astroglial viability and AQP4 expression. These findings indicate that PI3K/AKT may integrate p38 MAPK and ERK1/2 signaling pathways to regulate AQP4 expression when 67LR functionality is reduced. Thus, we suggest that 67LR-p38 MAPK/ERK1/2-PI3K-AKT-AQP4 signaling cascades may mediate serum extravasation and AQP4 expression in astroglio-vascular systems, which is one of the considerable therapeutic targets for vasogenic edema in various neurological diseases.

Evolving paradigms on the interplay of mitochondrial Hsp70 chaperone system in cell survival and senescence

The role of mitochondria within a cell has grown beyond being the prime source of cellular energy to one of the major signaling platforms. Recent evidence provides several insights into the crucial roles of mitochondrial chaperones in regulating the organellar response to external triggers. The mitochondrial Hsp70 (mtHsp70/Mortalin/Grp75) chaperone system plays a critical role in the maintenance of proteostasis balance in the organelle. Defects in mtHsp70 network result in attenuated protein transport and misfolding of polypeptides leading to mitochondrial dysfunction. The functions of Hsp70 are primarily governed by J-protein cochaperones. Although human mitochondria possess a single Hsp70, its multifunctionality is characterized by the presence of multiple specific J-proteins. Several studies have shown a potential association of Hsp70 and J-proteins with diverse pathological states that are not limited to their canonical role as chaperones. The role of mitochondrial Hsp70 and its co-chaperones in disease pathogenesis has not been critically reviewed in recent years. We evaluated some of the cellular interfaces where Hsp70 machinery associated with pathophysiological conditions, particularly in context of tumorigenesis and neurodegeneration. The mitochondrial Hsp70 machinery shows a variable localization and integrates multiple components of the cellular processes with varied phenotypic consequences. Although Hsp70 and J-proteins function synergistically in proteins folding, their precise involvement in pathological conditions is mainly idiosyncratic. This machinery is associated with a heterogeneous set of molecules during the progression of a disorder. However, the precise binding to the substrate for a specific physiological response under a disease subtype is still an undocumented area of analysis.

SMR peptide antagonizes mortalin promoted release of extracellular vesicles and affects mortalin protection from complement-dependent cytotoxicity in breast cancer cells and leukemia cells

Background: Mortalin/GRP-75/mt-hsp70 is a mitochondrial chaperone protein, found in the cytoplasm, endoplasmic reticulum and cytoplasmic vesicles. It functions in many cellular processes such as mitochondrial biogenesis, intracellular trafficking, cell proliferation, signaling, immortalization and tumorigenesis. Thus, inhibition of mortalin is a promising avenue for cancer therapy. Previous studies in our lab have suggested that mortalin contributes to breast cancer development and progression. We showed that tumor extracellular vesicle secretion was decreased by knockdown of mortalin expression using HIV-1 Nef SMR peptides. Specifically, these peptides can block extracellular vesicle secretion and mediate cell cycle arrest in MDA-MB-231 and MCF-7 breast cancer cells.

Aims: This study aims to investigate further the function and mechanism of interaction of PEG-SMR-CLU and SMR-CPP peptides with the chaperone protein mortalin and to explore the effect of SMR-derived peptides and mortalin expression on extracellular vesicle release and complement dependent cell toxicity in human breast cancer and leukemia cell lines.

Results: Our results demonstrated additional effects reversing the tumorigenicity of these cells. First, the modified SMRwt peptides reduced the expression of the mesenchymal marker vimentin (VIM). Second, exposure to the SMRwt peptide inhibited mortalin and complement C9 expression in MDA-MB-231, MCF-7 breast cancer cells and K562 leukemia cells as measured by the Western blot analysis. Third, the SMRwt peptides blocked the cancer cells’ ability to release extracellular vesicles, which we observed blocked extracellular vesicle-mediated release of complement, re-establishing complements mediated cell death in those peptide-treated cells.

Methods: We developed a series of peptides derived from the Secretion Modification Region (SMR) of HIV-1 Nef protein, modified by the addition of either a cell-penetrating peptide (CPP), a positively charged arginine-rich peptide derived from HIV-1 regulatory protein Tat, or a Clusterin-binding peptide (CLU), a molecular chaperone involved in protein secretion. Both CPP and CLU peptide sequences were added at the C-terminus of the Nef SMR peptide. The CLU-containing peptides were also modified with polyethylene glycol (PEG) to enhance solubility. After treatment of cells with the peptides, we used the MTT cell viability and complement-mediated cytotoxicity assays to confirm the inhibitory role of modified SMRwt peptides on the proliferation of MDA-MB-231 and MCF-7 breast cancer cells and K562 leukemia cells. Flow cytometry was used to determine complement mediated cell apoptosis and death. Western blot analysis was used to track SMR peptides impact on expression of mortalin, vimentin and complement C9 and to measure the expression of extracellular vesicle proteins. NanoSight analysis and acetylcholinesterase (AChE) assay were used for measuring extracellular vesicles particle size and concentration and acetylcholinesterase.

Conclusions: Mortalin promotes cell proliferation, metastasis, angiogenesis, downregulate apoptotic signaling. Thus, mortalin is a potential therapeutic target for cancer immunotherapy. The novel SMRwt peptides antagonize the functions of mortalin, blocking tumor extracellular vesicle release and extracellular vesicle-mediated release of complement. This leads to decreases in breast cancer cell metastasis and allows standard treatment of these late stage tumor cells, thus having important clinical implications for late stage breast cancer chemotherapy. These findings support further investigation into the therapeutic value of the SMR peptide in cancer metastasis.

NF-κB p65 promotes ovarian cancer cell proliferation and migration via regulating mortalin

Previous studies show that mortalin, a HSP70 family member, contributes to the development and progression of ovarian cancer. However, details of the transcriptional regulation of mortalin remain unknown. We aimed to determine whether NF‐κB p65 participates in the regulation of mortalin expression in ovarian cancer cells and to elucidate the underlying mechanism. Chromatin immunoprecipitation and luciferase reporter assay were used to identify mortalin gene sequences, to which NF‐κB p65 binds. Results indicated that NF‐κB p65 binds to the mortalin promoter at a site with the sequence ‘CGGGGTTTCA’. Using lentiviral pLVX‐NF‐κB‐puro and Lentivirus‐delivered NF‐κB short hairpin RNA (shRNA), we created ovarian cancer cell lines in which NF‐κB p65 was stably up‐regulated and down‐regulated. Using these cells, we found that downregulation of NF‐κB p65 inhibits the growth and migration of ovarian cancer cells. Further experimental evidence indicated that downregulation of NF‐κB p65 reduced mortalin, and upregulation of mortalin rescued the proliferation and migration of ovarian cancer cells reduced by NF‐κB p65 knockdown. In conclusion, NF‐κB p65 binds to the mortalin promoter and promotes ovarian cancer cells proliferation and migration via regulating mortalin.

Overexpressed Hsp70 alleviated formaldehyde-induced apoptosis partly via PI3K/Akt signaling pathway in human bronchial epithelial cells

Formaldehyde (FA) is a ubiquitous environmental pollutant, which can induce apoptosis in lung cell and is related to the pathogenesis of asthma, pneumonia, and chronic obstructive pulmonary disease. Heat shock protein 70 (Hsp70) is an ATP-dependent molecular chaperone and exhibits an anti-apoptosis ability in a variety of cells. Previous studies reported that the expression of Hsp70 was induced when organisms were exposed to FA. Whether Hsp70 plays a role in the FA-induced apoptosis and the involved cell signaling pathway remain largely unknown. In this study, human bronchial epithelial cells with overexpressed Hsp70 and the control were exposed to different concentrations of FA (0, 40, 80, and 160 μmol/L) for 24 hours. Apoptosis and the expression levels of PI3K, Akt, p-Akt, MEK, p-MEK, and GLI2 were detected by Annexin-APC/7AAD double-labeled flow cytometry and western blot. The results showed that overexpression of Hsp70 decreased the apoptosis induced by FA and alleviated the decline of PI3k and p-Akt significantly. Inhibitor (LY 294002, a specific inhibitor of PI3K-Akt) test result indicated that PI3K-Akt signaling pathway was involved in the inhibition of FA-induced apoptosis by Hsp70 overexpression and also active in the maintenance of GLI2 level. However, it also suggested that other signaling pathways activated by overexpressed Hsp70 participated in this process, which was needed to be elucidated in further research.

Cathelicidin-related antimicrobial peptide protects against myocardial ischemia/reperfusion injury

BACKGROUND

Cathelicidins are a major group of natural antimicrobial peptides which play essential roles in regulating host defense and immunity. In addition to the antimicrobial and immunomodulatory activities, recent studies have reported the involvement of cathelicidins in cardiovascular diseases by regulating inflammatory response and microvascular dysfunction. However, the role of cathelicidins in myocardial apoptosis upon cardiac ischemia/reperfusion (I/R) injury remains largely unknown.

METHODS

CRAMP (cathelicidin-related antimicrobial peptide) levels were measured in the heart and serum from I/R mice and in neonatal mouse cardiomyocytes treated with oxygen glucose deprivation/reperfusion (OGDR). Human serum cathelicidin antimicrobial peptide (LL-37) levels were measured in myocardial infarction (MI) patients. The role of CRAMP in myocardial apoptosis upon I/R injury was investigated in mice injected with the CRAMP peptide and in CRAMP knockout (KO) mice, as well as in OGDR-treated cardiomyocytes.

RESULTS

We observed reduced CRAMP level in both heart and serum samples from I/R mice and in OGDR-treated cardiomyocytes, as well as reduced LL-37 level in MI patients. Knockdown of CRAMP enhanced cardiomyocyte apoptosis, and CRAMP KO mice displayed increased infarct size and myocardial apoptosis. In contrast, the CRAMP peptide reduced cardiomyocyte apoptosis and I/R injury. The CRAMP peptide inhibited cardiomyocyte apoptosis by activation of Akt and ERK1/2 and phosphorylation and nuclear export of FoxO3a. c-Jun was identified as a negative regulator of the CRAMP gene. Moreover, lower level of serum LL-37/neutrophil ratio was associated with readmission and/or death in MI patients during 1-year follow-up.

CONCLUSIONS

CRAMP protects against cardiomyocyte apoptosis and cardiac I/R injury via activation of Akt and ERK and phosphorylation and nuclear export of FoxO3a. Increasing LL-37 might be a novel therapy for cardiac ischemic injury.

Mortalin is a distinct bio-marker and prognostic factor in serous ovarian carcinoma

This study focused on mortalin expression and its relevance to the prognosis in serous ovarian carcinoma, mortalin modulated cell malignant proliferation and EMT progression via Wnt/β-Catenin signaling pathway. In this study, data obtained from Oncomine database, Cancer Cell Line Encyclopedia (CCLE) analysis and Immunohistochemical (IHC) staining was used to assess the expression of mortalin in serous ovarian carcinoma. The prognostic value of mortalin was analyzed using Meier plotter database and Kaplan-Meier. MTT (3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2-H-tetrazolium bromide) assay, immunofluorescence (IF) staining, and colony formation assay were used to detect cell reproductive capacity. SK-OV-3 cell motility and epithelial-mesenchymal transition (EMT) were measured by wound-healing, migration and western-blot assays. Data from Oncomine showed that mortalin was highly expressed in serous ovarian carcinomas compared with corresponding normal controls. Similar results were found in CCLE analysis and in clinical specimens. High mortalin expression was associated with high histological grade and worse overall survival (OS) rate. The results of MTT analyses, IF staining, and colony formation assay indicated that MKT-077 (1-Ethyl-2-[[3-ethyl-5-(3-methyl-2(3H)-benzothiazolylidene)-4-oxo-2-thiazolidinylidene] methyl]-pyridinium chloride) suppressed the viability of SK-OV-3 cells. Besides, mortalin suppression restrained cell EMT progression by Wnt/β-Catenin signaling pathway. Taken together, mortalin is over-expressed in serous ovarian carcinoma. High mortalin expression could be a candidate for the prognostic indicator and a biomarker in serous ovarian carcinoma.

miR-208b targets Bax to protect H9c2 cells against hypoxia-induced apoptosis

BACKGROUND

miR-208 family members have been considered as promising biomarkers in myocardial infarction (MI). Among which, miR-208a and miR-499 are reported to function as ischemic injury promoting miRNAs. This study aimed to explore the in vitro function of miR-208b in MI, which has not been widely studied.

METHODS

RT-qPCR was conducted to measure the expression changes of miR-208b in MI patients, MI mouse model and H9c2 cells stimulated by hypoxia. H9c2 cells were subjected to hypoxia before which miR-208b expression was altered by transfection. CCK-8, flow cytometry and Western blot were performed to detect cell survival. Besides, the regulatory relationship between miR-208b, Bax, and PI3K/AKT was tested by luciferase reporter, RT-qPCR and Western blot.

RESULTS

Serum levels of miR-208b in MI patients were significantly higher than those in the healthy controls. Also, miR-208b was up-regulated in mouse model and cell model of MI. Overexpression of miR-208b protected H9c2 cells against hypoxia-induced apoptosis, as the viability was increased, apoptosis rate was decreased, Bax and Cytochrome c were down-regulated, and Bcl-2 was up-regulated. Bax was a target gene of miR-208b. And miR-208b could not protect H9c2 cells when Bax was overexpressed. More interestingly, miR-208b activated PI3K/AKT pathway via targeting Bax, and the activated PI3K/AKT pathway could further repress Bax expression. Finally, blocking PI3K/AKT pathway by using LY294002 eliminated the myocardioprotective effects of miR-208b.

CONCLUSION

miR-208b is highly expressed during MI, and miR-208b protects H9c2 cells against hypoxia-induced apoptosis. miR-208b exerts myocardioprotective effect via targeting Bax and activating PI3K/AKT pathway.

Neuroprotective Effects of Human Mesenchymal Stem Cells and Platelet-Derived Growth Factor on Human Retinal Ganglion Cells

Optic neuropathies such as glaucoma occur when retinal ganglion cells (RGCs) in the eye are injured. Strong evidence suggests mesenchymal stem cells (MSCs) could be a potential therapy to protect RGCs; however, little is known regarding their effect on the human retina. We, therefore, investigated if human MSCs (hMSCs), or platelet‐derived growth factor (PDGF) as produced by hMSC, could delay RGC death in a human retinal explant model of optic nerve injury. Our results showed hMSCs and the secreted growth factor PDGF‐AB could substantially reduce human RGC loss and apoptosis following axotomy. The neuroprotective pathways AKT, ERK, and STAT3 were activated in the retina shortly after treatments with labeling seen in the RGC layer. A dose dependent protective effect of PDGF‐AB was observed in human retinal explants but protection was not as substantial as that achieved by culturing hMSCs on the retina surface which resulted in RGC cell counts similar to those immediately post dissection. These results demonstrate that hMSCs and PDGF have strong neuroprotective action on human RGCs and may offer a translatable, therapeutic strategy to reduce degenerative visual loss. Stem Cells2018;36:65–78

Low-after-high glucose down-regulated Cx43 in H9c2 cells by autophagy activation via cross-regulation by the PI3K/Akt/mTOR and MEK/ERK1/2 signal pathways

PURPOSE

Hypoglycemia in diabetes is a strong predictor of cardiovascular events. High-glucose have been reported to alter connexin43 expression and to promote autophagy in cardiomyocytes. We investigated whether low-after-high glucose would influence connexin43 expression and autophagy in H9c2 cells.

METHODS

H9c2 cells were incubated in 33.3 mM glucose for 24 h followed by 2.5 mM glucose for 2, 4, 6, or 12 h with or without chloroquine (autophagy inhibitor), U0126 (MEK_1/2 inhibitor) or LY294002 (PI3K inhibitor). Cells incubated in 5.5, 33.3, or 2.5 mM glucose with or without inhibitors and in the presence of mannitol were used as controls. Protein expression was assayed by western blot, apoptosis was assayed by flow cytometry, cell proliferation was determined by MTT assays, and cytotoxicity was assayed by lactate dehydrogenase measurement.

RESULTS

Cytotoxicity and early apoptosis were increased and cell proliferation was decreased after exposure to low-after-high glucose, and these results were reversed by chloroquine and U0126 but were aggravated by LY294002. Connexin43 expression was downregulated in a time-dependent manner and was accompanied by upregulated expression of LC3-II, Beclin-1, p62, p-Akt, p-mTOR, and p-ERK_1/2. Chloroquine suppressed autophagy and reversed the downregulation of connexin43. U0126 inhibited ERK activation and decreased autophagy proteins expression but increased connexin43 expression. LY294002 suppressed p-Akt, activated autophagy, and decreased connexin43 expression. Interestingly, MEK_1/2 inhibition also increased p-Akt expression, but inhibition of PI3K led to p-ERK downregulation.

CONCLUSION

Culturing H9c2 cells under low-after-high glucose downregulated connexin43 by promoting autophagy through a mechanism involving the PI3K/Akt/mTOR and MEK/ERK_1/2 signaling pathways.

Mortalin overexpression predicts poor prognosis in early stage of non-small cell lung cancer

Mortalin is a member of the heat shock protein 70 family, which is involved in multiple cellular processes and may play key roles in promoting carcinogenesis. This study attempted to identify the clinical consequences of Mortalin overexpression and its roles in the prognostic evaluation of non-small cell lung cancer. A total of 120 non-small cell lung cancer samples paired with the adjacent non-tumor tissue samples and 10 normal lung tissues were selected for immunohistochemical staining for Mortalin. The localization of Mortalin was detected in A549 non-small cell lung cancer cells using immunofluorescence staining. The correlations between Mortalin overexpression and the clinical features of non-small cell lung cancers were evaluated using the chi-square test. The survival analysis was calculated via the Kaplan-Meier method and the Cox proportional hazard models. Our studies suggested that Mortalin exhibited a primarily cytoplasmic staining pattern in the non-small cell lung cancers. The rate of strongly positive Mortalin expression was higher in the non-small cell lung cancer samples than in the adjacent non-tumor samples or in normal lung tissues. Mortalin overexpression was significantly correlated with high histological grades, advanced stages, lymph node metastases, and lower disease-free survival and overall survival rates of the patients with non-small cell lung cancer. The survival analysis demonstrated that Mortalin overexpression was a significant independent prognostic factor in non-small cell lung cancer, especially for patients with early stage of non-small cell lung cancer. In conclusion, Mortalin is up-regulated in non-small cell lung cancer, and it may be a potential biomarker of prognostic evaluation and a molecular therapeutic target for patients with early stage of non-small cell lung cancer.

Apoptosis of rat hepatic stellate cells induced by diallyl trisulfide and proteomics profiling in vitro

Diallyl trisulfide (DATS), a major garlic derivative, inhibits cell proliferation and triggers apoptosis in a variety of cancer cell lines. However, the effects of DATS on hepatic stellate cells (HSCs) remain unknown. The aim of this study was to analyze the effects of DATS on cell proliferation and apoptosis, as well as the protein expression profile in rat HSCs. Rat HSCs were treated with or without 12 and 24 μg/mL DATS for various time intervals. Cell proliferation and apoptosis were determined using tetrazolium dye (MTT) colorimetric assay, bromodeoxyuridine (5-bromo-2'-deoxyuridine; BrdU) assay, Hoechst 33342 staining, electroscopy, and flow cytometry. Protein expression patterns in HSCs were systematically studied using 2-dimensional electrophoresis and mass spectrometry. DATS inhibited cell proliferation and induced apoptosis of HSCs in a time-dependent manner. We observed clear morphological changes in apoptotic HSCs and dramatically increased annexin V-positive - propidium iodide negative apoptosis compared with the untreated control group. Twenty-one significant differentially expressed proteins, including 9 downregulated proteins and 12 upregulated proteins, were identified after DATS administration, and most of them were involved in apoptosis. Our results suggest that DATS is an inducer of apoptosis in HSCs, and several key proteins may be involved in the molecular mechanism of apoptosis induced by DATS.

Relevance of mortalin to cancer cell stemness and cancer therapy

Mortalin/mtHsp70 is a member of Hsp70 family of proteins. Enriched in a large variety of cancers, it has been shown to contribute to the process of carcinogenesis by multiple ways including inactivation of tumor suppressor p53 protein, deregulation of apoptosis and activation of EMT signaling. In this study, we report that upregulation of mortalin contributes to cancer cell stemness. Several cancer cell stemness markers, such as ABCG2, OCT-4, CD133, ALDH1, CD9, MRP1 and connexin were upregulated in mortalin-overexpressing cells that showed higher ability to form spheroids. These cells also showed higher migration, and were less responsive to a variety of cancer chemotherapeutic drugs. Of note, knockdown of mortalin by specific shRNA sensitized these cells to all the drugs used in this study. We report that low doses of anti-mortalin molecules, MKT-077 and CAPE, also caused similar sensitization of cancer cells to chemotherapeutic drugs and hence are potential candidates for effective cancer chemotherapy.

Overexpression of GRP75 inhibits inflammation in a rat model of intracerebral hemorrhage

Glucose‑regulated protein 75 (GRP75) is a member of the heat shock protein 70 family and previous studies have demonstrated that GRP75 is involved in diseases of the central nervous system. However, the biological function of GRP75 in intracerebral hemorrhage (ICH) remains to be clarified. Thus, the aim of the present study was to evaluate the effects of GRP75 in a rat model of ICH. Western blotting was used to detect the protein expression of GRP75, active caspase‑3, Bax, Bcl‑2, p‑Akt and Akt in brain tissues following ICH. The levels of tumor necrosis factor‑α (TNF‑α) and interleukin (IL)‑1β were evaluated using ELISA assay. Expression of GRP75 mRNA and protein was demonstrated to be reduced in the brain tissues of rats with ICH compared with sham‑operated rats. In addition, overexpression of GRP75 in brain tissues with ICH significantly inhibited the production of the inflammatory cytokines TNF‑α and IL-1β and increased Bcl‑2/decreased Bax levels compared with ICH alone. Furthermore, overexpression of GRP75 in brain tissues with ICH resulted in significantly increased phosphorylation of Akt compared with ICH alone. Therefore, the present study demonstrated, for the first time to the best of our knowledge, significantly reduced GRP75 expression in brain tissues following ICH, and that overexpression of GRP75 inhibits inflammation and potentially inhibits neuronal apoptosis in a rat model of ICH. GRP75 may, therefore, represent a promising target in the treatment of ICH.

Selumetinib Attenuates Skeletal Muscle Wasting in Murine Cachexia Model through ERK Inhibition and AKT Activation

Cancer cachexia is a multifactorial syndrome affecting the skeletal muscle. Previous clinical trials showed that treatment with MEK inhibitor selumetinib resulted in skeletal muscle anabolism. However, it is conflicting that MAPK/ERK pathway controls the mass of the skeletal muscle. The current study investigated the therapeutic effect and mechanisms of selumetinib in amelioration of cancer cachexia. The classical cancer cachexia model was established via transplantation of CT26 colon adenocarcinoma cells into BALB/c mice. The effect of selumetinib on body weight, tumor growth, skeletal muscle, food intake, serum proinflammatory cytokines, E3 ligases, and MEK/ERK-related pathways was analyzed. Two independent experiments showed that 30 mg/kg/d selumetinib prevented the loss of body weight in murine cachexia mice. Muscle wasting was attenuated and the expression of E3 ligases, MuRF1 and Fbx32, was inhibited following selumetinib treatment of the gastrocnemius muscle. Furthermore, selumetinib efficiently reduced tumor burden without influencing the cancer cell proliferation, cumulative food intake, and serum cytokines. These results indicated that the role of selumetinib in attenuating muscle wasting was independent of cancer burden. Detailed analysis of the mechanism revealed AKT and mTOR were activated, while ERK, FoxO3a, and GSK3β were inhibited in the selumetinib -treated cachexia group. These indicated that selumetinib effectively prevented skeletal muscle wasting in cancer cachexia model through ERK inhibition and AKT activation in gastrocnemius muscle via cross-inhibition. The study not only elucidated the mechanism of MEK/ERK inhibition in skeletal muscle anabolism, but also validated selumetinib therapy as an effective intervention against cancer cachexia. Mol Cancer Ther; 16(2); 334-43. ©2016 AACR.

A plant alkaloid, veratridine, potentiates cancer chemosensitivity by UBXN2A-dependent inhibition of an oncoprotein, mortalin-2

Veratridine (VTD), an alkaloid derived from the Liliaceae plant shows anti-tumor effects; however, its molecular targets have not been thoroughly studied. Using a high-throughput drug screen, we found that VTD enhances transactivation of UBXN2A, resulting in upregulation of UBXN2A in the cytoplasm, where UBXN2A binds and inhibits the oncoprotein mortalin-2 (mot-2). VTD-treated cancer cells undergo cell death in UBXN2A- and mot-2-dependent manners. The cytotoxic function of VTD is grade-dependent, and the combined treatment with a sub-optimal dose of the standard chemotherapy, 5-Fluorouracil (5-FU) and etoposide, demonstrated a synergistic effect, resulting in higher therapeutic efficacy. VTD influences the CD44+ stem cells, possibly through UBXN2A-dependent inhibition of mot-2. The VTD-dependent expression of UBXN2A is a potential candidate for designing novel strategies for colon cancer treatment because: 1) In 50% of colon cancer patients, UBXN2A protein levels in tumor tissues are significantly lower than those in the adjacent normal tissues. 2) Cytoplasmic expression of the mot-2 protein is very low in non-cancerous cells; thus, VTD can produce tumor-specific toxicity while normal cells remain intact. 3) Finally, VTD or its modified analogs offer a valuable adjuvant chemotherapy strategy to improve the efficacy of 5-FU-based chemotherapy for colon cancer patients harboring WT-p53.

Oncogenic role of mortalin contributes to ovarian tumorigenesis by activating the MAPK-ERK pathway

Mortalin is frequently overexpressed in human malignancies. Previous studies have suggested that mortalin contributes to ovarian cancer development and progression, but further investigation is warranted. The aim of this study is to elucidate the mechanism of mortalin in ovarian cancer development and progression. In this study, lentivirus‐delivered mortalin short hairpin RNA (shRNA) was used to knockdown mortalin expression in A2780 and A2780/cis ovarian cancer cell lines, and lentiviral mortalin‐pLVX‐AcGFP was used to generate mortalin‐overexpressing cell lines. The results demonstrated that decreased mortalin expression reduced ovarian cancer cell proliferation, colony formation, migration and invasion by Cell Counting Kit‐8 assay, colony formation assay, wounding healing assay and Transwell cell invasion assay, respectively. Flow cytometry results suggested that mortalin promotes the G1 transition, leading to faster restoration of a normal cell‐cycle distribution. Cell‐cycle proteins, including C‐myc and Cyclin‐D1, significantly increased, and Cyclin‐B1 remarkably decreased upon mortalin down‐regulation. Western blot analysis showed that mortalin knockdown significantly decreased p‐c‐Raf and phospho‐extracellular–regulated protein kinases (p‐ERK1/2) pathways but not the Jun N‐terminal kinase pathway, whereas mortalin overexpression had the opposite effect. Taken together, these results indicate that mortalin is an oncogenic factor, and mitogen‐activated protein kinase‐ERK signalling pathway activation by mortalin may contribute to ovarian cancer development and progression.

The clinicopathological significance of Mortalin overexpression in invasive ductal carcinoma of breast

Background

Mortalin/GRP75 is a ubiquitous mitochondrial chaperone which related to the cytosolic heat shock protein 70 (HSP70), and plays a role in carcinogenesis. This study aims to investigate the Mortalin expression in breast cancer and its correlation with the outcome of the patients with breast cancer.

Methods

A total of 155 invasive ductal carcinoma of breast patients with strict follow-up, 52 ductal carcinoma in situ (DCIS) and 45 adjacent non-tumor breast tissues were selected for immunohistochemical (IHC) staining of Mortalin protein. The localization of Mortalin protein was detected in MDA-MB231 breast cancer cells using immunofluorescence (IF) staining. The correlations between overexpression of Mortalin and the clinical features of patients with breast cancer were evaluated using chi-square test and Fisher’s exact tests. The survival rates were calculated by the Kaplan-Meier method, and the relationship between prognostic factors and patient survival was also analyzed by the Cox proportional hazard models.

Results

Mortalin protein showed a mainly cytoplasmic staining pattern in breast cancers by using IHC staining in paraffin embedded breast cancer tissues and IF staining in MDA-MB231 breast cancer cells. The strongly positive rate of Mortalin protein was 63.9 % (99/155) in invasive ductal carcinoma of breast and was significantly higher than in DCIS 34.6 % (18/52) and adjacent non-tumor tissues 15.6 % (7/45). Overexpression of Mortalin was closely correlated with histological grade, clinical stage, lymph node metastasis, lower disease free survival (DFS) and overall survival (OS) rates of patients with breast cancer. Moreover, multivariate analysis suggested that Mortalin emerged as a significant independent prognostic factor along with clinical stage and Her2 expression status in patients with breast cancer.

Conclusions

Mortalin is upregulated in breast cancer, and may be a useful poor prognostic biomarker as well as a potential therapeutic target for patients with breast cancer.

Structural studies of UBXN2A and mortalin interaction and the putative role of silenced UBXN2A in preventing response to chemotherapy

Overexpression of the oncoprotein mortalin in cancer cells and its protein partners enables mortalin to promote multiple oncogenic signaling pathways and effectively antagonize chemotherapy-induced cell death. A UBX-domain-containing protein, UBXN2A, acts as a potential mortalin inhibitor. This current study determines whether UBXN2A effectively binds to and occupies mortalin's binding pocket, resulting in a direct improvement in the tumor's sensitivity to chemotherapy. Molecular modeling of human mortalin's binding pocket and its binding to the SEP domain of UBXN2A followed by yeast two-hybrid and His-tag pull-down assays revealed that three amino acids (PRO442, ILE558, and LYS555) within the substrate-binding domain of mortalin are crucial for UBXN2A binding to mortalin. As revealed by chase experiments in the presence of cycloheximide, overexpression of UBXN2A seems to interfere with the mortalin-CHIP E3 ubiquitin ligase and consequently suppresses the C-terminus of the HSC70-interacting protein (CHIP)-mediated destabilization of p53, resulting in its stabilization in the cytoplasm and upregulation in the nucleus. Overexpression of UBXN2A causes a significant inhibition of cell proliferation and the migration of colon cancer cells. We silenced UBXN2A in the human osteosarcoma U2OS cell line, an enriched mortalin cancer cell, followed by a clinical dosage of the chemotherapeutic agent 5-fluorouracil (5-FU). The UBXN2A knockout U2OS cells revealed that UBXNA is essential for the cytotoxic effect achieved by 5-FU. UBXN2A overexpression markedly increased the apoptotic response of U2OS cells to the 5-FU. In addition, silencing of UBXN2A protein suppresses apoptosis enhanced by UBXN2A overexpression in U2OS. The knowledge gained from this study provides insights into the mechanistic role of UBXN2A as a potent mortalin inhibitor and as a potential chemotherapy sensitizer for clinical application.

PI3K/Akt/mTOR and Ras/Raf/MEK/ERK signaling pathways inhibitors as anticancer agents: Structural and pharmacological perspectives

The protein kinases regulate cellular functions such as transcription, translation, proliferation, growth and survival by the process of phosphorylation. Over activation of signaling pathways play a major role in oncogenesis. The PI3K signaling pathway is dysregulated almost in all cancers due to the amplification, genetic mutation of PI3K gene and the components of the PI3K pathway themselves. Stimulation of the PI3K/Akt/mTOR and Ras/Raf/MEK/ERK pathways enhances growth, survival, and metabolism of cancer cells. Recently, the PI3K/Akt/mTOR and Ras/Raf/MEK/ERK signaling pathways have been identified as promising therapeutic targets for cancer therapy. The kinase inhibitors with enhanced specificity and improved pharmacokinetics have been considered for design and development of anticancer agents. This review focuses primarily on the Ras/Raf/MEK/ERK and PI3K/Akt/mTOR signaling pathways as therapeutic targets of anticancer drugs, their specific and dual inhibitors, structure activity relationships (SARs) and inhibitors under clinical trials.

c-MYC responds to glucose deprivation in a cell-type-dependent manner

Metabolic reprogramming supports cancer cells’ demands for rapid proliferation and growth. Previous work shows that oncogenes, such as MYC, hypoxia-inducible factor 1 (HIF1), have a central role in driving metabolic reprogramming. A lot of metabolic enzymes, which are deregulated in most cancer cells, are the targets of these oncogenes. However, whether metabolic change affects these oncogenes is still unclear. Here we show that glucose deprivation (GD) affects c-MYC protein levels in a cell-type-dependent manner regardless of P53 mutation status. GD dephosphorylates and then decreases c-MYC protein stability through PI3K signaling pathway in HeLa cells, but not in MDA-MB-231 cells. Role of c-MYC in sensitivity of GD also varies with cell types. c-MYC-mediated glutamine metabolism partially improves the sensitivity of GD in MDA-MB-231 cells. Our results reveal that the heterogeneity of cancer cells in response to metabolic stress should be considered in metabolic therapy for cancer.

Targeting Mortalin by Embelin Causes Activation of Tumor Suppressor p53 and Deactivation of Metastatic Signaling in Human Breast Cancer Cells

Embelin, a natural quinone found in the fruits of Embelia ribes, is commonly used in Ayurvedic home medicine for a variety of therapeutic potentials including anti-inflammation, anti-fever, anti-bacteria and anti-cancer. Molecular mechanisms of these activities and cellular targets have not been clarified to-date. We demonstrate that the embelin inhibits mortalin-p53 interactions, and activates p53 protein in tumor cells. We provide bioinformatics, molecular docking and experimental evidence to the binding affinity of embelin with mortalin and p53. Binding of embelin with mortalin/p53 abrogates their complex resulted in nuclear translocation and transcriptional activation function of p53 causing growth arrest in cancer cells. Furthermore, analyses of growth factors and metastatic signaling using antibody membrane array revealed their downregulation in embelin-treated cells. We also found that the embelin causes transcriptional attenuation of mortalin and several other proteins involved in metastatic signaling in cancer cells. Based on these molecular dynamics and experimental data, it is concluded that the anticancer activity of embelin involves targeting of mortalin, activation of p53 and inactivation of metastatic signaling.

Nucleocytoplasmic Translocation of UBXN2A Is Required for Apoptosis during DNA Damage Stresses in Colon Cancer Cells

The subcellular localization, expression level, and activity of anti-cancer proteins alter in response to intrinsic and extrinsic cellular stresses to reverse tumor progression. The purpose of this study is to determine whether UBXN2A, an activator of the p53 tumor suppressor protein, has different subcellular compartmentalization in response to the stress of DNA damage. We measured trafficking of the UBXN2A protein in response to two different DNA damage stresses, UVB irradiation and the genotoxic agent Etoposide, in colon cancer cell lines. Using a cytosol-nuclear fractionation technique followed by western blot and immunofluorescence staining, we monitored and quantitated UBXN2A and p53 proteins as well as p53's downstream apoptotic pathway.

We showed that the anti-cancer protein UBXN2A acts in the early phase of cell response to two different DNA damage stresses, being induced to translocate into the cytoplasm in a dose- and time-dependent manner. UVB-induced cytoplasmic UBXN2A binds to mortalin-2 (mot-2), a known oncoprotein in colon tumors. UVB-dependent upregulation of UBXN2A in the cytoplasm decreases p53 binding to mot-2 and activates apoptotic events in colon cancer cells. In contrast, the shRNA-mediated depletion of UBXN2A leads to significant reduction in apoptosis in colon cancer cells exposed to UVB and Etoposide. Leptomycin B (LMB), which was able to block UBXN2A nuclear export following Etoposide treatment, sustained p53-mot-2 interaction and had partially antagonistic effects with Etoposide on cell apoptosis. The present study shows that nucleocytoplasmic translocation of UBXN2A in response to stresses is necessary for its anti-cancer function in the cytoplasm. In addition, LMB-dependent suppression of UBXN2A's translocation to the cytoplasm upon stress allows the presence of an active mot-2 oncoprotein in the cytoplasm, resulting in p53 sequestration as well as activation of other mot-2-dependent growth promoting pathways.

Cross talk of the first-line defense TLRs with PI3K/Akt pathway, in preconditioning therapeutic approach

Toll-like receptor family (TLRs), pattern recognition receptors, is expressed not only on immune cells but also on non-immune cells, including cardiomyocytes, fibroblasts, and vascular endothelial cells. One main function of TLRs in the non-immune system is to regulate apoptosis. TLRs are the central mediators in hepatic, pulmonary, brain, and renal ischemic/reperfusion (I/R) injury. Up-regulation of TLRs and their ligation by either exogenous or endogenous danger signals plays critical roles in ischemia/reperfusion-induced tissue damage. Conventional TLR-NF-κB pathways are markedly activated in failing and ischemic myocardium. Recent studies have identified a cross talk between TLR activation and the PI3K/Akt pathway. The activation of TLRs is proposed to be the most potent preconditioning method after ischemia, to improve the cell survival via the mechanism involved the PI3K/Akt signaling pathway and to attenuate the subsequent TLR-NF-κB pathway stimulation. Thus, TLRs could be a great target in the new treatment approaches for myocardial I/R injury.

Cross talk of the first-line defense TLRs with PI3K/Akt pathway, in preconditioning therapeutic approach

Toll-like receptor family (TLRs), pattern recognition receptors, is expressed not only on immune cells but also on non-immune cells, including cardiomyocytes, fibroblasts, and vascular endothelial cells. One main function of TLRs in the non-immune system is to regulate apoptosis. TLRs are the central mediators in hepatic, pulmonary, brain, and renal ischemic/reperfusion (I/R) injury. Up-regulation of TLRs and their ligation by either exogenous or endogenous danger signals plays critical roles in ischemia/reperfusion-induced tissue damage. Conventional TLR-NF-κB pathways are markedly activated in failing and ischemic myocardium. Recent studies have identified a cross talk between TLR activation and the PI3K/Akt pathway. The activation of TLRs is proposed to be the most potent preconditioning method after ischemia, to improve the cell survival via the mechanism involved the PI3K/Akt signaling pathway and to attenuate the subsequent TLR-NF-κB pathway stimulation. Thus, TLRs could be a great target in the new treatment approaches for myocardial I/R injury.

Involvement of mortalin/GRP75/mthsp70 in the mitochondrial impairments induced by A53T mutant α-synuclein

Mutations and excessive accumulation of α-synuclein (α-syn) can lead to the degeneration of dopaminergic neurons, indicating a pivotal role of α-syn in the pathogenesis of Parkinson's disease (PD). Although how α-syn contributes to PD is still elusive, mitochondrial impairments have been reported to be implicated in. Mortalin, a molecular chaperone mainly located in mitochondria, has been linked to the pathogenesis of PD in recent studies. Moreover, some proteomics studies indicate that mortalin is associated with PD-related proteins, including α-syn. Therefore it is of interest to understand the function of mortalin in the mitochondrial disruption induced by A53T α-syn overexpression. The present study modulated the expression of mortalin and detected the effect of mortalin on the mitochondrial impairments induced by A53T α-syn in SH-SY5Y cells. Our data revealed that A53T α-syn could disrupt mitochondrial dynamics and increase the neuronal susceptibility to neurotoxin rotenone. The expression of mortalin decreased significantly in dopaminergic cells overexpressing A53T α-syn; furthermore, the down-regulation of mortalin could attenuate the disrupted mitochondrial dynamics by reducing α-syn translocation to mitochondria, suggesting that a compensatory mechanism of mortalin might be implicated in the pathogenesis of PD.

Functional significance of point mutations in stress chaperone mortalin and their relevance to Parkinson disease

Mortalin/mtHsp70/Grp75 (mot-2), a heat shock protein 70 family member, is an essential chaperone, enriched in cancers, and has been shown to possess pro-proliferative and anti-apoptosis functions. An allelic form of mouse mortalin (mot-1) that differs by two amino acids, M618V and G624R, in the C terminus substrate-binding domain has been reported. Furthermore, genome sequencing of mortalin from Parkinson disease patients identified two missense mutants, R126W and P509S. In the present study, we investigated the significance of these mutations in survival, proliferation, and oxidative stress tolerance in human cells. Using mot-1 and mot-2 recombinant proteins and specific antibodies, we performed screening to find their binding proteins and then identified ribosomal protein L-7 (RPL-7) and elongation factor-1 α (EF-1α), which differentially bind to mot-1 and mot-2, respectively. We demonstrate that mot-1, R126W, or P509S mutant (i) lacks mot-2 functions involved in carcinogenesis, such as p53 inactivation and hTERT/hnRNP-K (heterogeneous nuclear ribonucleoprotein K) activation; (ii) causes increased level of endogenous oxidative stress; (iii) results in decreased tolerance of cells to exogenous oxidative stress; and (iv) shows differential binding and impact on the RPL-7 and EF-1α proteins. These factors may mediate the transformation of longevity/pro-proliferative function of mot-2 to the premature aging/anti-proliferative effect of mutants, and hence may have significance in cellular aging, Parkinson disease pathology, and prognosis.

GRP75 Involves in Retinal Ganglion Cell Apoptosis After Rat Optic Nerve Crush

Glucose-regulated protein 75 (GRP75), a member of the heat-shock protein 70 family, is known to protect cells from stress-induced injury. However, information regarding its distribution and possible function in the retina is limited. In this study, we performed an optic nerve crush (ONC) model in adult rats and found that GRP75 was significantly upregulated in the retina after ONC. Double immunofluorescent staining revealed that GRP75 was localized in the retinal ganglion cells (RGCs). We also examined the expression profile of active caspase3, whose change was correlated with the expression profile of GRP75. In addition, we utilized co-staining of GRP75 and active caspase3 and terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) to study their correlation in the retina following ONC. Furthermore, the expressions of Bax, cytochrome c (Cytc), p-extracellular-signal-regulated kinases (ERK)1/2, and p-AKT were enhanced in the retina after ONC, and they were parallel with the expression profile of GRP75. Based on our data, we speculated that GRP75 might play an important role in RGCs apoptosis following ONC.

Identification and functional characterization of nuclear mortalin in human carcinogenesis

The Hsp70 family protein mortalin is an essential chaperone that is frequently enriched in cancer cells and exists in various subcellular sites, including the mitochondrion, plasma membrane, endoplasmic reticulum, and cytosol. Although the molecular mechanisms underlying its multiple subcellular localizations are not yet clear, their functional significance has been revealed by several studies. In this study, we examined the nuclear fractions of human cells and found that the malignantly transformed cells have more mortalin than the normal cells. We then generated a mortalin mutant that lacked a mitochondrial targeting signal peptide. It was largely localized in the nucleus, and, hence, is called nuclear mortalin (mot-N). Functional characterization of mot-N revealed that it efficiently protects cancer cells against endogenous and exogenous oxidative stress. Furthermore, compared with the full-length mortalin overexpressing cancer cells, mot-N derivatives showed increased malignant properties, including higher proliferation rate, colony forming efficacy, motility, and tumor forming capacity both in in vitro and in vivo assays. We demonstrate that mot-N promotes carcinogenesis and cancer cell metastasis by inactivation of tumor suppressor protein p53 functions and by interaction and functional activation of telomerase and heterogeneous ribonucleoprotein K (hnRNP-K) proteins.

The TLR9 ligand, CpG-ODN, induces protection against cerebral ischemia/reperfusion injury via activation of PI3K/Akt signaling

BACKGROUND

Toll-like receptors (TLRs) have been shown to be involved in cerebral ischemia/reperfusion (I/R) injury. TLR9 is located in intracellular compartments and recognizes CpG-DNA. This study examined the effect of CpG-ODN on cerebral I/R injury.

METHODS AND RESULTS

C57BL/6 mice were treated with CpG-ODN by i.p. injection 1 hour before the mice were subjected to cerebral ischemia (60 minutes) followed by reperfusion (24 hours). Scrambled-ODN served as control-ODN. Untreated mice, subjected to cerebral I/R, served as I/R control. The effect of inhibitory CpG-ODN (iCpG-ODN) on cerebral I/R injury was also examined. In addition, we examined the therapeutic effect of CpG-ODN on cerebral I/R injury by administration of CpG-ODN 15 minutes after cerebral ischemia. CpG-ODN administration significantly decreased cerebral I/R-induced infarct volume by 69.7% (6.4±1.80% vs 21.0±2.85%, P<0.05), improved neurological scores, and increased survival rate, when compared with the untreated I/R group. Therapeutic administration of CpG-ODN also significantly reduced infarct volume by 44.7% (12.6±2.03% vs 22.8±2.54%, P<0.05) compared with untreated I/R mice. Neither control-ODN, nor iCpG-ODN altered I/R-induced cerebral injury or neurological deficits. Nissl staining showed that CpG-ODN treatment preserved neuronal morphology in the ischemic hippocampus. Immunoblot showed that CpG-ODN administration increased Bcl-2 levels by 41% and attenuated I/R-increased levels of Bax and caspase-3 activity in ischemic brain tissues. Importantly, CpG-ODN treatment induced Akt and GSK-3β phosphorylation in brain tissue and cultured microglial cells. PI3K inhibition with LY294002 abolished CpG-ODN-induced protection.

CONCLUSION

CpG-ODN significantly reduces cerebral I/R injury via a PI3K/Akt-dependent mechanism. Our data also indicate that CpG-ODN may be useful in the therapy of cerebral I/R injury.

Activation of spinal phosphatidylinositol 3-kinase/protein kinase B mediates pain behavior induced by plantar incision in mice

The etiology of postoperative pain may be different from antigen-induced inflammatory pain and neuropathic pain. However, central neural plasticity plays a key role in incision pain. It is also known that phosphatidylinositol 3-kinase (PI3K) and protein kinase B/Akt (PKB/Akt) are widely expressed in laminae I-IV of the spinal horn and play a critical role in spinal central sensitization. In the present study, we explored the role of PI3K and Akt in incision pain behaviors. Plantar incision induced a time-dependent activation of spinal PI3K-p110γ and Akt, while activated Akt and PI3K-p110γ were localized in spinal neurons or microglias, but not in astrocytes. Pre-treatment with PI3K inhibitors, wortmannin or LY294002 prevented the activation of Akt brought on by plantar incision in a dose-dependent manner. In addition, inhibition of spinal PI3K signaling pathway prevented pain behaviors (dose-dependent) and spinal Fos protein expression caused by plantar incision. These data demonstrated that PI3K signaling mediated pain behaviors caused by plantar incision in mice.

SHetA2 interference with mortalin binding to p66shc and p53 identified using drug-conjugated magnetic microspheres

SHetA2 is a small molecule flexible heteroarotinoid (Flex-Het) with promising cancer prevention and therapeutic activity. Extensive preclinical testing documented lack of SHetA2 toxicity at doses 25 to 150 fold above effective doses. Knowledge of the SHetA2 molecular target(s) that mediate(s) the mechanism of SHetA2 action is critical to appropriate design of clinical trials and improved analogs. The aim of this study was to develop a method to identify SHetA2 binding proteins in cancer cells. A known metabolite of SHetA2 that has a hydroxyl group available for attachment was synthesized and conjugated to a linker for attachment to a magnetic microsphere. SHetA2-conjugated magnetic microspheres and unconjugated magnetic microspheres were separately incubated with aliquots of a whole cell protein extract from the A2780 human ovarian cancer cell line. After washing away non-specifically bound proteins with the protein extraction buffer, SHetA2-binding proteins were eluted with an excess of free SHetA2. In two independent experiments, an SDS gel band of about 72 kDa was present at differential levels in wells of eluent from SHetA2-microspheres in comparison to wells of eluent from unconjugated microspheres. Mass spectrometry analysis of the bands (QStar) and straight eluents (Orbitrap) identified mortalin (HSPA9) to be present in the eluent from SHetA2-microspheres and not in eluent from unconjugated microspheres. Co-immunoprecipitation experiments demonstrated that SHetA2 interfered with mortalin binding to p53 and p66 Src homologous-collagen homologue (p66shc) inside cancer cells. Mortalin and SHetA2 conflictingly regulate the same molecules involved in mitochondria-mediated intrinsic apoptosis. The results validate the power of this protocol for revealing drug targets.

Human leukemic cell lines synthesize hyaluronan to avoid senescence and resist chemotherapy

Hyaluronan (HA) is one of the major components of the extracellular matrix. Several solid tumors produce high levels of HA, which promotes survival and multidrug resistance (MDR). HA oligomers (oHAs) can block HA effects. However, little is known about the role of HA in hematological malignancies. The aim of this work was to determine whether HA or its oligomers can modulate the proliferation of leukemia cells as well as their effect on MDR. Receptors and signaling pathways involved were also analyzed. For this purpose, the human leukemic cell lines K562 and Kv562, which are sensitive and resistant to Vincristine (VCR), respectively, were used. We demonstrated that HA induced cell proliferation in both cell lines. On K562 cells, this effect was mediated by cluster differentiation 44 (CD44) and activation of both phosphoinositide 3-kinase (PI3K)/protein kinase B (Akt) and mitogen-activated protein kinase kinase (MEK)/extracellular signal-regulated kinase (ERK) pathways, whereas on Kv562 cells, the effect was mediated by receptor for hyaluronan-mediated motility (RHAMM) and PI3K/Akt activation. The inhibition of HA synthesis by 4-methylumbelliferone (4MU) decreased cell line proliferation and sensitized Kv562 to the effect of VCR through P-glycoprotein (Pgp) inhibition, in both cases with senescence induction. Moreover, oHAs inhibited K562 proliferation mediated by CD44 as well as Akt and ERK down-regulation. Furthermore, oHAs sensitized Kv562 cells to VCR by Pgp inhibition inducing senescence. We postulate that the synthesis of HA would promote leukemia progression mediated by the triggering of the above-mentioned proliferative signals. These findings highlight the potential use of oHAs and 4MU as coadjuvant for drug-resistant leukemia.

cIAP-2 protects cardiac fibroblasts from oxidative damage: an obligate regulatory role for ERK1/2 MAPK and NF-κB

Cardiac fibroblasts are resistant to several pro-apoptotic factors that prevail in the diseased myocardium. Resistance to death signals may, in the short-term, enable these cells to play a central role in tissue repair following myocyte loss but, in the long-term, facilitate their persistence in the infarct scar, resulting in disproportionate stromal growth and pump dysfunction. Surprisingly, the molecular basis of apoptosis resistance in cardiac fibroblasts remains unclear. We explored the recruitment of anti-apoptotic mechanisms in cardiac fibroblasts subjected to oxidative stress, a major component of ischemia-reperfusion injury and heart failure. Cardiac fibroblasts exposed to H2O2 expressed enhanced levels of anti-apoptotic cIAP-2 mRNA and protein, revealed by real time PCR and western blot analysis, respectively. Pulmonary fibroblasts did not express cIAP-2 and were more susceptible than cardiac fibroblasts to H2O2. cIAP-2 knockdown by RNA interference promoted apoptosis in H2O2-treated cardiac fibroblasts. Electrophoretic mobility shift assay showed NF-κB activation in cells under oxidative stress. NF-κB inhibition in H2O2-treated cells resulted in significant attenuation of cIAP-2 mRNA and protein expression and apoptosis, indicating involvement of NF-κB in cell survival via regulation of cIAP-2. Further, pCMV promoter-driven constitutive expression of cIAP-2 reduced viability loss in NF-κB-inhibited cardiac fibroblasts exposed to oxidative stress. H2O2 also caused ERK1/2 activation, which, upon inhibition, prevented IκBα degradation and nuclear translocation of NF-κB. Moreover, ERK1/2 inhibition attenuated H2O2-induced cIAP-2 expression and compromised viability in H2O2-treated cardiac fibroblasts. We propose for the first time that ERK1/2-dependent activation of NF-κB and consequent induction of cIAP-2 protects cardiac fibroblasts from oxidative damage.