αB-crystallin, an effector of unfolded protein response, confers anti-VEGF resistance to breast cancer via maintenance of intracrine VEGF in endothelial cells

Mature human induced pluripotent stem cell-derived cardiomyocytes promote angiogenesis through alpha-B crystallin

BACKGROUND

Human induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs) can be used to treat heart diseases; however, the optimal maturity of hiPSC-CMs for effective regenerative medicine remains unclear. We aimed to investigate the benefits of long-term cultured mature hiPSC-CMs in injured rat hearts.

METHODS

Cardiomyocytes were differentiated from hiPSCs via monolayer culturing, and the cells were harvested on day 28 or 56 (D28-CMs or D56-CMs, respectively) after differentiation. We transplanted D28-CMs or D56-CMs into the hearts of rat myocardial infarction models and examined cell retention and engraftment via in vivo bioluminescence imaging and histological analysis. We performed transcriptomic sequencing analysis to elucidate the genetic profiles before and after hiPSC-CM transplantation.

RESULTS

Upregulated expression of mature sarcomere genes in vitro was observed in D56-CMs compared with D28-CMs. In vivo bioluminescence imaging studies revealed increased bioluminescence intensity of D56-CMs at 8 and 12 weeks post-transplantation. Histological and immunohistochemical analyses showed that D56-CMs promoted engraftment and maturation in the graft area at 12 weeks post-transplantation. Notably, D56-CMs consistently promoted microvessel formation in the graft area from 1 to 12 weeks post-transplantation. Transcriptomic sequencing analysis revealed that compared with the engrafted D28-CMs, the engrafted D56-CMs enriched genes related to blood vessel regulation at 12 weeks post-transplantation. As shown by transcriptomic and western blot analyses, the expression of a small heat shock protein, alpha-B crystallin (CRYAB), was significantly upregulated in D56-CMs compared with D28-CMs. Endothelial cell migration was inhibited by small interfering RNA-mediated knockdown of CRYAB when co-cultured with D56-CMs in vitro. Furthermore, CRYAB overexpression enhanced angiogenesis in the D28-CM grafts at 4 weeks post-transplantation.

CONCLUSIONS

Long-term cultured mature hiPSC-CMs promoted engraftment, maturation and angiogenesis post-transplantation in infarcted rat hearts. CRYAB, which was highly expressed in D56-CMs, was identified as an angiogenic factor from mature hiPSC-CMs. This study revealed the benefits of long-term culture, which may enhance the therapeutic potential of hiPSC-CMs.

Inflammatory Bowel Diseases: An Updated Overview on the Heat Shock Protein Involvement

Inflammatory bowel diseases (IBDs) represent chronic idiopathic disorders, including Crohn's disease (CD) and ulcerative colitis (UC), in which one of the trigger factors is represented by aberrant immune interactions between the intestinal epithelium and the intestinal microbiota. The involvement of heat shock proteins (HSPs) as etiological and pathogenetic factors is becoming of increasing interest. HSPs were found to be differentially expressed in the intestinal tissues and sera of patients with CD and UC. It has been shown that HSPs can play a dual role in the disease, depending on the stage of progression. They can support the inflammatory and fibrosis process, but they can also act as protective factors during disease progression or before the onset of one of the worst complications of IBD, colorectal cancer. Furthermore, HSPs are able to mediate the interaction between the intestinal microbiota and intestinal epithelial cells. In this work, we discuss the involvement of HSPs in IBD considering their genetic, epigenetic, immune and molecular roles, referring to the most recent works present in the literature. With our review, we want to shed light on the importance of further exploring the role of HSPs, or even better, the role of the molecular chaperone system (CS), in IBD: various molecules of the CS including HSPs may have diagnostic, prognostic and therapeutic potential, promoting the creation of new drugs that could overcome the side-effects of the therapies currently used.

The role of CRYAB in tumor prognosis and immune infiltration: A Pan-cancer analysis

Purpose

There is evidence that the Crystallin Alpha B (CRYAB) gene is involved in the regulation of the tumor microenvironment and influences tumor prognosis in some cancers. However, the role of CRYAB gene in prognosis and immunology in pan-cancer is still unclear.

Methods

In this study, we analyzed the transcriptional profiles and survival data of cancer patients from The Cancer Genome Atlas (TCGA) database. CRYAB gene and its relationships with pan-cancer were analyzed using R packages, TIMER2.0, GEPIA2, Sangerbox, UALCAN, cBioPortal, ESTIMATE algorithm, and STRING. Besides, real-time fluorescence quantitative polymerase chain reaction (RT-qPCR) was utilized to detect CRYAB expression in KIRC and a human KIRC cell line (Caki-1).

Results

We found that CRYAB expression was different in tumors and adjacent tumors in human cancers, affecting patients' prognosis in 15 cancer types. Additionally, CRYAB expression significantly correlated with tumor microenvironment (TME), immune checkpoints (ICP), tumor mutational burden (TMB), and microsatellite instability (MSI) in human cancers. Besides, CRYAB expression was positively associated with the immune infiltration of cancer-associated fibroblasts (CAFs) and endothelial cells in most human cancers. Based on enrichment analysis, the most prevalent CRYAB gene mechanism in malignant tumors may be through anti-apoptotic activity. Moreover, some FDA-approved drugs were found to be associated with CRYAB and might be potential cancer therapeutic candidates.

Conclusions

CRYAB is a crucial component of the TME and influences immune cell infiltration, making it a promising biomarker to assess immune infiltration and prognosis in many malignancies.

Alpha-B-Crystallin overexpression is sufficient to promote tumorigenesis and metastasis in mice

BACKGROUND

αB-Crystallin is a heat shock chaperone protein which binds to misfolded proteins to prevent their aggregation. It is overexpressed in a wide-variety of cancers. Previous studies using human cancer cell lines and human xenograft models have suggested potential tumor promoter (oncogene) roles for αB-Crystallin in a wide-spectrum of cancers.

METHODS

To determine the causal relationship between CRYAB overexpression and cancer, we generated a Cryab overexpression knock-in mouse model and monitor them for development of spontaneous and carcinogen (DMBA)-induced tumorigenesis. In order to investigate the mechanism of malignancies observed in this model multiple techniques were used such as immunohistochemical characterizations of tumors, bioinformatics analysis of publically available human tumor datasets, and generation of mouse embryonic fibroblasts (MEFs) for in vitro assays (clonogenic survival and migration assays and proteome analysis by mass-spectrometry).

RESULTS

This model revealed that constitutive overexpression of Cryab results in the formation of a variety of lethal spontaneous primary and metastatic tumors in mice. In vivo, the overexpression of Cryab correlated with the upregulation of epithelial-to-mesenchymal (EMT) markers, angiogenesis and some oncogenic proteins including Basigin. In vitro, using E1A/Ras transformed MEFs, we observed that the overexpression of Cryab led to the promotion of cell survival via upregulation of Akt signaling and downregulation of pro-apoptotic pathway mediator JNK, with subsequent attenuation of apoptosis as assessed by cleaved caspase-3 and Annexin V staining.

CONCLUSIONS

Overall, through the generation and characterization of Cryab overexpression model, we provide evidence supporting the role of αB-Crystallin as an oncogene, where its upregulation is sufficient to induce tumors, promote cell survival and inhibit apoptosis.

The role of heat shock proteins in metastatic colorectal cancer: A review

Heat shock proteins (HSPs) are a large molecular chaperone family classified by their molecular weights, including HSP27, HSP40, HSP60, HSP70, HSP90, and HSP110. HSPs are likely to have antiapoptotic properties and participate actively in various processes such as tumor cell proliferation, invasion, metastases, and death. In this review, we discuss comprehensively the functions of HSPs associated with the progression of colorectal cancer (CRC) and metastasis and resistance to cancer therapy. Taken together, HSPs have numerous clinical applications as biomarkers for cancer diagnosis and prognosis and potential therapeutic targets for CRC and its related metastases.

Exosomal LBH inhibits epithelial-mesenchymal transition and angiogenesis in nasopharyngeal carcinoma via downregulating VEGFA signaling

The limb-bud and heart (LBH) gene was reported to suppress nasopharyngeal carcinoma (NPC) progression in our previous study. Distant metastasis predominantly accounts for the unsatisfactory prognosis of NPC treatment, in which epithelial-mesenchymal transition (EMT) and tumor angiogenesis are of great significance. The roles of exosomes in mediating NPC progression have been highlighted in recent researches, and attempts have been made to explore the clinical application of NPC exosomes. Here we investigated the function of the LBH gene in NPC exosomes, and its potential mechanism. NPC xenografts were constructed, showing that vascular endothelial growth factor A (VEGFA) expression and neovascularity were attenuated by LBH overexpression, together with diminished EMT progression. NPC-derived exosomes were isolated, identified and applied for in vitro/in vivo experiments, and the exosomal distribution of LBH was elevated in exosomes derived from LBH-upregulated cells. Ectopic LBH, αB-crystallin (CRYAB) and VEGFA expression was induced by lentiviral infection or plasmid transfection to explore their functions in modulating EMT and angiogenesis in NPC. The addition of LBH+ NPC exosomes during a Matrigel plug assay in mice suppressed in vivo angiogenesis, and the treatment of human umbilical vein endothelial cells (HUVECs) with LBH+ NPC exosomes inhibited cellular proliferation, migration and tube formation. The interactions among LBH, CRYAB and VEGFA were confirmed by colocalization and fluorescence resonance energy transfer (FRET) assays, and extracellular VEGFA secretion from both HUVECs and NPC cells under the treatment with LBH+ NPC exosomes was diminished according to ELISA results. We concluded that exosomal LBH inhibits EMT progression and angiogenesis in the NPC microenvironment, and that its effects are partially implemented by modulation of VEGFA expression, secretion and related signaling. Thus, LBH could serve as a promising therapeutic target in VEGFA-focused NPC treatment.

Alpha-crystallin B chains in trastuzumab-resistant breast cancer cells promote endothelial cell tube formation through activating mTOR

The specific human epidermal growth factor receptor 2 (HER2)-targeting monoclonal antibody trastuzumab shows considerable clinical efficacy in patients with HER2-overexpressing breast cancer. However, about 20% of patients who receive trastuzumab in the adjuvant setting relapse, and approximately half of patients with metastatic HER2-positive breast cancer develop resistance to trastuzumab within 1 year. Although the mechanism of trastuzumab resistance has been explored broadly, whether and how angiogenesis participates in trastuzumab resistance is unclear. Here, we examined the association between angiogenesis and trastuzumab resistance by using a trastuzumab-resistant cell line (SKBR3-TR). Compared with that from the parental trastuzumab-sensitive SKBR3 cells, the culture supernatant from SKBR3-TR cells significantly increased the sprouting of endothelial cells. To identify intercellular features that contribute to the induction of endothelial tube formation, proteomics revealed that α-crystallin B chain (αB-crystallin) was upregulated in SKBR3-TR cells. Moreover, silencing of αB-crystallin significantly repressed SKBR3-TR-induced tube formation, and knockdown of αB-crystallin in SKBR3-TR cells suppressed the activation of mechanistic target of rapamycin (mTOR) in endothelial cells. In addition, treatment with rapamycin, an inhibitor of mTOR, reversed the SKBR3-TR-induced promotion of tube formation. In summary, αB-crystallin enhanced the ability of SKBR3-TR cells to activate mTOR in endothelial cells and thus promote angiogenesis.

Lithium preserves peritoneal membrane integrity by suppressing mesothelial cell αB-crystallin

Life-saving renal replacement therapy by peritoneal dialysis (PD) is limited in use and duration by progressive impairment of peritoneal membrane integrity and homeostasis. Preservation of peritoneal membrane integrity during chronic PD remains an urgent but long unmet medical need. PD therapy failure results from peritoneal fibrosis and angiogenesis caused by hypertonic PD fluid (PDF)-induced mesothelial cytotoxicity. However, the pathophysiological mechanisms involved are incompletely understood, limiting identification of therapeutic targets. We report that addition of lithium chloride (LiCl) to PDF is a translatable intervention to counteract PDF-induced mesothelial cell death, peritoneal membrane fibrosis, and angiogenesis. LiCl improved mesothelial cell survival in a dose-dependent manner. Combined transcriptomic and proteomic characterization of icodextrin-based PDF-induced mesothelial cell injury identified αB-crystallin as the mesothelial cell protein most consistently counter-regulated by LiCl. In vitro and in vivo overexpression of αB-crystallin triggered a fibrotic phenotype and PDF-like up-regulation of vascular endothelial growth factor (VEGF), CD31-positive cells, and TGF-β-independent activation of TGF-β-regulated targets. In contrast, αB-crystallin knockdown decreased VEGF expression and early mesothelial-to-mesenchymal transition. LiCl reduced VEGF release and counteracted fibrosis- and angiogenesis-associated processes. αB-crystallin in patient-derived mesothelial cells was specifically up-regulated in response to PDF and increased in peritoneal mesothelial cells from biopsies from pediatric patients undergoing PD, correlating with markers of angiogenesis and fibrosis. LiCl-supplemented PDF promoted morphological preservation of mesothelial cells and the submesothelial zone in a mouse model of chronic PD. Thus, repurposing LiCl as a cytoprotective PDF additive may offer a translatable therapeutic strategy to combat peritoneal membrane deterioration during PD therapy.

CD63-mediated cloaking of VEGF in small extracellular vesicles contributes to anti-VEGF therapy resistance

Despite wide use of anti-vascular endothelial growth factor (VEGF) therapy for many solid cancers, most individuals become resistant to this therapy, leading to disease progression. Therefore, new biomarkers and strategies for blocking adaptive resistance of cancer to anti-VEGF therapy are needed. As described here, we demonstrate that cancer-derived small extracellular vesicles package increasing quantities of VEGF and other factors in response to anti-VEGF therapy. The packaging process of VEGF into small extracellular vesicles (EVs) is mediated by the tetraspanin CD63. Furthermore, small EV-VEGF (eVEGF) is not accessible to anti-VEGF antibodies and can trigger intracrine VEGF signaling in endothelial cells. eVEGF promotes angiogenesis and enhances tumor growth despite bevacizumab treatment. These data demonstrate a mechanism where VEGF is partitioned into small EVs and promotes tumor angiogenesis and progression. These findings have clinical implications for biomarkers and therapeutic strategies for ovarian cancer.

Limb-bud and heart (LBH) inhibits cellular migration, invasion and epithelial-mesenchymal transition in nasopharyngeal carcinoma via downregulating αB-crystallin expression

Limb-bud and heart (LBH) gene has received increasing attention in recent cancer studies. Here we investigated the role of the LBH gene in regulating the metastasis capacity and epithelial-mesenchymal transition (EMT) of nasopharyngeal carcinoma (NPC) cells, and its potential mechanism. The expressions of LBH and αB-crystallin (CRYAB) were modulated by lentiviral infection, or plasmid/siRNA transfection, and the phosphorylation of p38 was suppressed by an inhibitor, to explore their functions in modulating NPC cell phenotypes, as well as the relationships of these factors with each other. Cellular proliferation, migration and invasion were examined by RTCA system, Transwell assays and Matrigel Transwell assays respectively. The EMT progression was indicated by RT-qPCR and Western blotting measuring the expressions of EMT biomarkers. NPC xenografts were constrcucted, and formed tumors were sectioned for morphology and immunohistofluorescence. The interaction between LBH and CRYAB was examined by colocalization and Fluorescence resonance energy transfer (FRET) analysis. We reached the conclusion that LBH inhibits the proliferation, migration, invasion and EMT of NPC cells, and its effects were partially achieved by suppressing p38 phosphorylation, which subsequently downregulates the mRNA expression and phosphorylation of CRYAB, while CRYAB directly interacts with LBH in NPC cells. This LBH-related pathway we revealed provides a novel therapeutic target for nasopharyngeal carcinoma research.

MicroRNAs in laser-induced choroidal neovascularization in mice and rats: their expression and potential therapeutic targets

Choroidal neovascularization characterizes wet age-related macular degeneration. Choroidal neovascularization formation involves a primarily angiogenic process that is combined with both inflammation and proteolysis. A primary cause of choroidal neovascularization pathogenesis is alterations in pro- and anti-angiogenic factors derived from the retinal pigment epithelium, with vascular endothelium growth factor being mainly responsible for both clinical and experimental choroidal neovascularization. MicroRNAs (miRNAs) which are short, non-coding, endogenous RNA molecules have a major role in regulating various pathological processes, including inflammation and angiogenesis. A review of recent studies with the mouse laser-induced choroidal neovascularization model has shown alterations in miRNA expression in choroidal neovascularization tissues and could be potential therapeutic targets for wet age-related macular degeneration. Upregulation of miR-505 (days 1 and 3 post-laser), miR-155 (day 14) occurred in retina; miR-342-5p (days 3 and 7), miR-126-3p (day 14) in choroid; miR-23a, miR-24, miR-27a (day 7) in retina/choroid; miR-505 (days 1 and 3) in retinal pigment epithelium/choroid; downregulation of miR-155 (days 1 and 3), miR-29a, miR-29b, miR-29c (day 5), miR-93 (day 14), miR-126 (day 14) occurred in retinal pigment epithelium/choroid. Therapies using miRNA mimics or inhibitors were found to decrease choroidal neovascularization lesions. Choroidal neovascularization development was reduced by overexpression of miR-155, miR-188-5p, miR-(5,B,7), miR-126-3p, miR-342-5p, miR-93, miR-126, miR-195a-3p, miR-24, miR-21, miR-31, miR-150, and miR-184, or suppression of miR-505, miR-126-3p, miR-155, and miR-23/27. Further studies are warranted to determine miRNA expression in mouse laser-induced choroidal neovascularization models in order to validate and extend the reported findings. Important experimental variables need to be standardized; these include the strain and age of animals, gender, number and position of laser burns to the eye, laser parameters to induce choroidal neovascularization lesions including wavelength, power, spot size, and duration.

AlphaB-crystallin and breast cancer: role and possible therapeutic strategies

AlphaB-crystallin (HSPB5) is one of the most prominent and well-studied members of the small heat shock protein (sHsp) family. To date, it is known that this protein modulates significant cellular processes and therefore, it is not surprising that its deregulation is involved in various human pathologies, including cancer diseases. Despite the pathogenic significance of HSPB5 in cancer and its regulatory mechanism related to aggressiveness is poorly understood, several reports describe the association of breast carcinoma progression with HSPB5, whose expression is also considered an independent predictor of breast cancer metastasis to the brain. Indeed, numerous authors indicate HSPB5 as a new valuable biomarker for clinicopathological parameters and poor prognosis in breast cancer. Considering the cytoprotective, anti-apoptotic, pro-angiogenic, and pro-metastatic properties of the sHsps, it is not surprising that they are considered as promising targets for anticancer treatment, even though, at present, a deeper understanding of their mode of action is needed to allow the development of precise therapeutic interventions. Data on the direct inhibition of different sHsps demonstrate promising results in cancer pathologies; however, specific strategies against HSPB5 have not been considered. This review highlights the most relevant findings on HSPB5 and its role in breast cancer, as well as the possible strategies in using HSPB5 inhibition for therapeutic purposes.

Retinal pigment epithelium and age-related macular degeneration: A review of major disease mechanisms

Age‐related macular degeneration (AMD) is a progressive degenerative disease that is the leading cause of vision loss in the elderly population. Degeneration/dysregulation of the retinal pigment epithelium (RPE), a supportive monolayer of cells underlying the photoreceptors, is commonly seen in patients with AMD. While treatment exists for the neovascular/wet form of AMD, there is currently no cure for the non‐exudative/dry form of AMD, making it imperative to understand the pathogenesis of this disease. Although our understanding of the aetiology of AMD has increased over the years, the underlying disease mechanism has not yet been identified, mainly due to the multifactorial nature of this disease. Herein, we review some of the commonly proposed degeneration pathways of RPE cells and their role in the pathogenesis of AMD; including activation of the complement cascade, oxidative stress‐induced cell death mechanisms, dysfunctional mitochondria and the role of crystallins in AMD disease progression.

Atf6α impacts cell number by influencing survival, death and proliferation

Background

A growing body of literature suggests the cell–intrinsic activity of Atf6α during ER stress responses has implications for tissue cell number during growth and development, as well as in adult biology and tumorigenesis [1]. This concept is important, linking the cellular processes of secretory protein synthesis and endoplasmic reticulum stress response with functional tissue capacity and organ size. However, the field contains conflicting observations, especially notable in secretory cell types like the pancreatic beta cell.

Scope of review

Here we summarize current knowledge of the basic biology of Atf6α, along with the pleiotropic roles Atf6α plays in cell life and death decisions and possible explanations for conflicting observations. We include studies investigating the roles of Atf6α in cell survival, death and proliferation using well-controlled methodology and specific validated outcome measures, with a focus on endocrine and metabolic tissues when information was available.

Major conclusions

The net outcome of Atf6α on cell survival and cell death depends on cell type and growth conditions, the presence and degree of ER stress, and the duration and intensity of Atf6α activation. It is unquestioned that Atf6α activity influences the cell fate decision between survival and death, although opposite directions of this outcome are reported in different contexts. Atf6α can also trigger cell cycle activity to expand tissue cell number through proliferation. Much work remains to be done to clarify the many gaps in understanding in this important emerging field.

Qishen Granule alleviates endoplasmic reticulum stress-induced myocardial apoptosis through IRE-1-CRYAB pathway in myocardial ischemia

ETHNOPHARMACOLOGICAL RELEVANCE

Qishen Granule (QSG) is a prevailing traditional Chinese medicine formula that displays impressive cardiovascular protection in clinical. However, underlying mechanisms by which QSG alleviates endoplasmic reticulum (ER) stress-induced apoptosis in myocardial ischemia still remain unknown.

AIM OF THE STUDY

This study aims to elucidate whether QSG ameliorates ER stress-induced myocardial apoptosis to protect against myocardial ischemia via inositol requiring enzyme 1 (IRE-1)-αBcrystallin (CRYAB) signaling pathway.

MATERIALS AND METHODS

Left anterior descending (LAD) ligation induced-ischemic heart model and oxygen-glucose deprivation-reperfusion (OGD/R)-induced H9C2 cells injury model were established to clarify the effects and potential mechanism of QSG. Ethanol extracts of QSG (2.352 g/kg) were orally administered for four weeks and Ginaton Tablets (100 mg/kg) was selected as a positive group in vivo. In vitro, QSG (800 μg/ml) or STF080310 (an inhibitor of IRE-1, 10 μM) was co-cultured under OGD/R in H9C2 cells. Inhibition of IRE-1 was conducted in H9C2 cells to further confirm the exact mechanism. Finally, to define the active components of anti-cardiomyocyte apoptosis in QSG which absorbed into the blood, we furtherly used the OGD/R-induced cardiomyocyte apoptosis model to evaluate the effects.

RESULTS

QSG treatment improved cardiac function, ameliorated inflammatory cell infiltration and myocardial apoptosis. Similar effects were revalidated in OGD/R-induced H9C2 injury model. Western blots demonstrated QSG exerted anti-apoptotic effects by regulating apoptosis-related proteins, including increasing Bcl-2 and caspase 3/12, reducing the expressions of Bax and cleaved-caspase 3/12. Mechanistically, the IRE-1-CRYAB signaling pathway was significantly activated by QSG. Co-treatment with STF080310, the IRE-1 specific inhibitor significantly compromised the protective effects of QSG in vitro. Especially, the active components of QSG including Formononetin, Tanshinone IIA, Tanshinone I, Cryptotanshinon and Harpagoside showed significantly anti-apoptosis effects.

CONCLUSION

QSG protected against ER stress-induced myocardial apoptosis via the IRE-1-CRYAB pathway, which is proposed as a promising therapeutic target for myocardial ischemia.

Gene Expression Profiles Identified Novel Urine Biomarkers for Diagnosis and Prognosis of High-Grade Bladder Urothelial Carcinoma

Bladder urothelial carcinoma (BC) has been identified as one of the most common malignant neoplasm worldwide. High-grade bladder urothelial carcinoma (HGBC) is aggressive with a high risk of recurrence, progression, metastasis, and poor prognosis. Therefore, HGBC clinical management is still a challenge. We performed the present study to seek new urine biomarkers for HGBC and investigate how they promote HGBC progression and thus affect the prognosis based on large-scale sequencing data. We identified the overlapped differentially expressed genes (DEGs) by combining GSE68020 and The Cancer Genome Atlas (TCGA) datasets. Subsequent receiver operating characteristic (ROC) curves, Kaplan-Meier (KM) curves, and Cox regression were conducted to test the diagnostic and prognostic role of the hub genes. Chi-square test and logistic regression were carried out to analyze the associations between clinicopathologic characteristics and the hub genes. Ultimately, we performed gene set enrichment analysis (GSEA), protein-protein interaction (PPI) networks, and Bayesian networks (BNs) to explore the underlying mechanisms by which ECM1, CRYAB, CGNL1, and GPX3 are involved in tumor progression. Immunohistochemistry based on The Human Protein Atlas and quantitative real-time polymerase chain reaction based on urine samples confirmed the downregulation and diagnostic values of the hub genes in HGBC. In conclusion, our study indicated that CRYAB, CGNL1, ECM1, and GPX3 are potential urine biomarkers of HGBC. These four novel urine biomarkers will have attractive applications to provide new diagnostic methods, prognostic predictors and treatment targets for HGBC, which could improve the prognosis of HGBC patients, if validated by further experiments and larger prospective clinical trials.

Endoplasmic Reticulum Stress Pathway, the Unfolded Protein Response, Modulates Immune Function in the Tumor Microenvironment to Impact Tumor Progression and Therapeutic Response

Despite advances in cancer therapy, several persistent issues remain. These include cancer recurrence, effective targeting of aggressive or therapy-resistant cancers, and selective treatments for transformed cells. This review evaluates the current findings and highlights the potential of targeting the unfolded protein response to treat cancer. The unfolded protein response, an evolutionarily conserved pathway in all eukaryotes, is initiated in response to misfolded proteins accumulating within the lumen of the endoplasmic reticulum. This pathway is initially cytoprotective, allowing cells to survive stressful events; however, prolonged activation of the unfolded protein response also activates apoptotic responses. This balance is key in successful mammalian immune response and inducing cell death in malignant cells. We discuss how the unfolded protein response affects cancer progression, survival, and immune response to cancer cells. The literature shows that targeting the unfolded protein response as a monotherapy or in combination with chemotherapy or immunotherapies increases the efficacy of these drugs; however, systemic unfolded protein response targeting may yield deleterious effects on immune cell function and should be taken into consideration. The material in this review shows the promise of both approaches, each of which merits further research.

Radiation-Stimulated Translocation of CD166 and CRYAB to the Endothelial Surface Provides Potential Vascular Targets on Irradiated Brain Arteriovenous Malformations

Vascular targeting with pro-thrombotic antibody-conjugates is a promising biological treatment for brain arteriovenous malformations (bAVMs). However, targeted drug delivery relies on the identification of unique or overexpressed markers on the surface of a target cell. In the absence of inherent biological markers, stereotactic radiosurgery may be used to prime induction of site-specific and targetable molecular changes on the endothelial surface. To investigate lumen-accessible, endothelial targets induced by radiation, we combined Gamma knife surgery in an AVM animal model with in vivo biotin-labeling and comparative proteomics. Two proteins, αB-crystallin (CRYAB)-a small heat shock protein that normally acts as an intracellular chaperone to misfolded proteins-and activated leukocyte cell adhesion molecule CD166, were further validated for endothelial surface expression after irradiation. Immunostaining of endothelial cells in vitro and rat AVM tissue ex vivo confirmed de novo induction of CRYAB following irradiation (20 Gy). Western analysis demonstrated that CRYAB accumulated intracellularly as a 20 kDa monomer, but, at the cell surface, a novel 65 kDa protein was observed, suggesting radiation stimulates translocation of an atypical CRYAB isoform. In contrast, CD166 had relatively high expression in non-irradiated cells, localized predominantly to the lateral surfaces. Radiation increased CD166 surface exposure by inducing translocation from intercellular junctions to the apical surface without significantly altering total protein levels. These findings reinforce the dynamic molecular changes induced by radiation exposure, particularly at the cell surface, and support further investigation of radiation as a priming mechanism and these molecules as putative targets for focused drug delivery in irradiated tissue.

Progression of the role of CRYAB in signaling pathways and cancers

CRYAB is a member of the small heat shock protein family, first discovered in the lens of the eye, and involved in various diseases, such as eye and heart diseases and even cancers, for example, breast cancer, lung cancer, prostate cancer, and ovarian cancer. In addition, CRYAB proteins are involved in a variety of signaling pathways including apoptosis, inflammation, and oxidative stress. This review summarizes the recent progress concerning the role of CRYAB in signaling pathways and diseases. Therefore, the role of CRYAB in signaling pathways and cancers is urgently needed. This article reviews the regulation of CRYAB in the apoptotic inflammatory signaling pathway and its role in cancers progression and as a key role in anti-cancer therapy targeting CRYAB in an effort to improve outcomes for patients with metastatic disease.

Regulation of tumor-stroma interactions by the unfolded protein response

The unfolded protein response (UPR) is a conserved adaptive pathway that helps cells cope with the protein misfolding burden within the endoplasmic reticulum (ER). Imbalance between protein folding demand and capacity in the ER leads to a situation called ER stress that is often observed in highly proliferative and secretory tumor cells. As such, activation of the UPR signaling has emerged as a key adaptive mechanism promoting cancer progression. It is becoming widely acknowledged that, in addition to its intrinsic effect on tumor biology, the UPR can also regulate tumor microenvironment. In this review, we discuss how the UPR coordinates the crosstalk between tumor and stromal cells, such as endothelial cells, normal parenchymal cells, and immune cells. In addition, we further describe the involvement of ER stress signaling in the response to current treatments as well as its impact on antitumor immunity mainly driven by immunogenic cell death. Finally, in this context, we discuss the relevance of targeting ER stress/UPR signaling as a potential anticancer approach.

HspB5 correlates with poor prognosis in colorectal cancer and prompts epithelial-mesenchymal transition through ERK signaling

Alpha B-crystallin (HspB5) is abnormally expressed in tumor tissues and portends a poor prognosis in cancer patients. However, the role of HspB5 in colorectal cancer (CRC) is still unclear. Seventy CRC patients and 40 healthy volunteers were sampled from August 2012 to March 2015 in order to determine the clinical significance of HspB5. In vitro cellular studies were used to validate its molecular mechanisms in CRC. Our clinical data indicated that HspB5 was up-regulated, and had a positive association with TNM stage CRC patients. The expression level of HspB5 in CRC patients was closely correlated with MMP7 and E-cadherin, two core epithelial–mesenchymal transition (EMT) gene products. The in vitro studies revealed that high HspB5 expression could prompt tumor cell proliferation and invasion, as well as EMT. Gene-microarray analysis suggested three significant signaling pathways (PI3K, p38 and ERK) were involved in HspB5-induced EMT. Signal transduction pathway inhibitors and HspB5 gene knockdown models suggested that HspB5 promotes CRC tumorigenesis and EMT progression through ERK signaling pathways. In summary, HspB5 maybe trigger the EMT in CRC by activating the ERK signaling pathway. It is a potential tumor biomarker for CRC diagnosis and prognosis.

Association of breast carcinoma growth with a non-canonical axis of IFNγ/IDO1/TSP1

Reciprocal interactions between cancers and the surrounding microenvironment have an important role in tumour evolution. In this study, our data suggested that through thrombospondin 1 (TSP1), tumour-associated microvessel provides a dormant niche to sustain inactive status of breast invasive ductal carcinoma (IDC) cells. TSP1 levels in the tumour stroma were negatively correlated with vascular indoleamine 2,3-dioxygenase 1 (IDO1) in IDC tissues. IDO1 is an intracellular enzyme initiating the first and rate-limited step of tryptophan breakdown. Lower stromal TSP1 levels and positive tumour vascular IDO1 staining seems to associate with poor survive of patients with IDC. IDC cells induced a significantly increase in IDO1 expression in endothelial cells (ECs). IFNγ exerts a similar effect on ECs. We hypothesized a tryptophan starvation theory that since tryptophan is essential for the synthesis of TSP1, IDO1 induce a decrease in tryptophan availability and a reduction in TSP1 synthesis in ECs, leading to overcoming the dormancy state of IDC cells and exacerbating conditions such as tumour invasion and metastasis. These findings identify a non-canonical role of IFNγ/IDO1/TSP1 axis in microvascular niche-dominated dormancy of breast invasive ductal carcinoma with a solid foundation for further investigation of therapeutic and prognostic relevance.

Synergistic anti-tumor effects of bevacizumab and tumor targeted polymerized VEGF siRNA nanoparticles

A variety of VEGF inhibitors have been reported to treat cancers by suppressing tumor angiogenesis. Bevacizumab, a monoclonal VEGF antibody, was the first FDA approved anti-angiogenic agent for cancer treatments. However, bevacizumab shows modest therapeutic efficiency and often cause resistant problem in significant populations of cancer patients. To solve these problem, we investigated the therapeutic efficacy of siRNA drugs targeting VEGF and combination of the RNAi drug with bevacizumab for cancer treatments. For efficient VEGF siRNA delivery, chemically polymerized siRNAs were complexed with thiolated-glycol chitosan (psi(VEGF)/tGC). The poly-VEGF siRNA and thiolated-glycol chitosan formed stable nanoparticles via electrostatic interaction and chemical crosslinking, and showed high accumulation in tumor tissues resulting in efficient gene silencing. Both VEGF siRNA nanoparticles and bevacizumab had efficient therapeutic effects in tumor xenograft mouse models. Interestingly, most pronounced therapeutic efficacy was observed when the two distinct VEGF inhibitors were treated in combination revealing synergistic effects. The results showed that the psi(VEGF)/tGC nanoparticle mediated knockdown of VEGF exerts anti-tumor effects and the combination treatments with bevacizumab can extend the treatments options to conventional bevacizumab treatments for cancer therapy.

Genomic markers of panitumumab resistance including ERBB2/ HER2 in a phase II study of KRAS wild-type (wt) metastatic colorectal cancer (mCRC)

A prospective study was conducted to identify biomarkers associated with resistance to panitumumab monotherapy in patients with metastatic colorectal cancer (mCRC). Patients with previously treated, codon 12/13 KRAS wt, mCRC were prospectively administered panitumumab 6 mg/kg IV q2weeks. Of 34 panitumumab-treated patients, 11 (32%) had progressive disease at 8 weeks and were classified as non-responders.

A Nanostring nCounter-based assay identified a 5-gene expression signature (ERBB2, MLPH, IRX3, MYRF, and KLK6) associated with panitumumab resistance (P = 0.001). Immunohistochemistry and in situ hybridization determined that the HER2 (ERBB2) protein was overexpressed in 4/11 non-responding and 0/21 responding cases (P = 0.035). Two non-responding tumors had ERBB2 gene amplification only, and one demonstrated both ERBB2 amplification and mutation. A non-codon 12/13 KRAS mutation occurred in one panitumumab-resistant patient and was mutually exclusive with ERBB2/HER2 abnormalities.

This study identifies a 5-gene signature associated with non-response to single agent panitumumab, including a subgroup of non-responders with evidence of aberrant ERBB2/HER2 signaling. KRAS wt tumors resistant to EGFRi may be identified by gene signature analysis, and the HER2 pathway plays an important role in resistance to therapy.

Strand and Cell Type-specific Function of microRNA-126 in Angiogenesis

microRNAs or miRs have been shown to be pivotal modulators of vascular development. The strand and cell type-specific function of miR-126 in angiogenesis, especially pathological angiogenesis, remains poorly defined. We characterized the retinal vascular phenotype of miR-126^-/- mice, and tested the function of miR-126 strands (miR-126-3p and -5p) using in vitro angiogenesis models and a mouse model of neovascular age-related macular degeneration. We found that miR-126 is critical for retinal vascular development but has dual function in pathological angiogenesis. miR-126^-/- mice showed defective postnatal retinal vascular development and remodeling, which is partially rescued by genetic knockout of its target gene Spred-1. Surprisingly, either silencing miR-126-3p by LNA-antimiR or overexpressing miR-126-3p by miRNA mimic repressed laser-induced choroidal neovascularization. To dissect the underlying mechanism, we found in endothelial cells, silencing of miR-126-3p repressed angiogenesis, while overexpression of miR-126-5p enhanced angiogenesis. However, in retinal pigment epithelial cells, miR-126-3p repressed vascular endothelial growth factor (VEGF-A) expression via a novel mechanism of regulating αB-Crystallin promoter activity and by directly targeting VEGF-A 3'-untranslated region. These findings provide first genetic evidence that miR-126 is required for the development of different retinal vascular layers, and also uncover a strand and cell type-specific function of miR-126 in ocular pathological angiogenesis.

Quantitative proteomic analysis of mice corneal tissues reveals angiogenesis-related proteins involved in corneal neovascularization

Corneal neovascularization (CNV) was induced in Balb/c mice by alkali burns in the central area of the cornea with a diameter of 2.5mm. After fourteen days, the cornea from one eye was collected for histological staining for CNV examination, while the cornea from the other eye of the same mouse was harvested for proteomic analysis. The label-free quantitative proteomic approach was applied to analyze five normal corneal tissues (normal group mice n=5) and five corresponding neovascularized corneal tissues (model group mice n=5). A total of 2124 proteins were identified, and 1682 proteins were quantified from these corneal tissues. Among these quantified proteins, 290 proteins were significantly changed between normal and alkali burned corneal tissues. Of these significantly changed proteins, 35 were reported or predicted as angiogenesis-related proteins. Then, these 35 proteins were analyzed using Ingenuity Pathway Analysis Software, resulting in 26 proteins enriched and connected to each other in the protein-protein interaction network, such as Lcn-2, αB-crystallin and Serpinf1 (PEDF). These three significantly changed proteins were selected for further Western blotting validation. Consistent with the quantitative proteomic results, Western blotting showed that Lcn-2 and αB-crystallin were significantly up-regulated in CNV model, while PEDF was down-regulated. This study provided increased understanding of angiogenesis-related proteins involved in corneal vascular development, which will be useful in the ophthalmic clinic of specifically target angiogenesis.

αB-crystallin: Portrait of a malignant chaperone as a cancer therapeutic target

αB-crystallin is a widely expressed member of the small heat shock protein family that protects cells from stress by its dual function as a molecular chaperone to preserve proteostasis and as a cell death antagonist that negatively regulates components of the conserved apoptotic cell death machinery. Deregulated expression of αB-crystallin occurs in a broad array of solid tumors and has been linked to tumor progression and poor clinical outcomes. This review will focus on new insights into the molecular mechanisms by which oncogenes, oxidative stress, matrix detachment and other tumor microenvironmental stressors deregulate αB-crystallin expression. We will also review accumulating evidence pointing to an essential role for αB-crystallin in the multi-step metastatic cascade whereby tumor cells colonize distant organs by circumventing a multitude of barriers to cell migration and survival. Finally, we will evaluate emerging strategies to therapeutically target αB-crystallin and/or interacting proteins to selectively activate apoptosis and/or derail the metastatic cascade in an effort to improve outcomes for patients with metastatic disease.

c-Raf promotes angiogenesis during normal growth plate maturation

Extracellular phosphate plays a key role in growth plate maturation by inducing Erk1/2 (Mapk3/1) phosphorylation, leading to hypertrophic chondrocyte apoptosis. The Raf kinases induce Mek1/2 (Map2k1/2) and Erk1/2 phosphorylation; however, a role for Raf kinases in endochondral bone formation has not been identified. Ablation of both A-Raf (Araf) and B-Raf (Braf) in chondrocytes does not alter growth plate maturation. Because c-Raf (Raf1) phosphorylation is increased by extracellular phosphate and c-Raf is the predominant isoform expressed in hypertrophic chondrocytes, chondrocyte-specific c-Raf knockout mice (c-Raf(f/f);ColII-Cre(+)) were generated to define a role for c-Raf in growth plate maturation. In vivo studies demonstrated that loss of c-Raf in chondrocytes leads to expansion of the hypertrophic layer of the growth plate, with decreased phospho-Erk1/2 immunoreactivity and impaired hypertrophic chondrocyte apoptosis. However, cultured hypertrophic chondrocytes from these mice did not exhibit impairment of phosphate-induced Erk1/2 phosphorylation. Studies performed to reconcile the discrepancy between the in vitro and in vivo hypertrophic chondrocyte phenotypes revealed normal chondrocyte differentiation in c-Raf(f/f);ColII-Cre(+) mice and lack of compensatory increase in the expression of A-Raf and B-Raf. However, VEGF (Vegfa) immunoreactivity in the hypertrophic chondrocytes of c-Raf(f/f);ColII-Cre(+) mice was significantly reduced, associated with increased ubiquitylation of VEGF protein. Thus, c-Raf plays an important role in growth plate maturation by regulating vascular invasion, which is crucial for replacement of terminally differentiated hypertrophic chondrocytes by bone.

Advances in small-molecule drug discovery for triple-negative breast cancer

Triple-negative breast cancer (TNBC) is a subtype of poor prognosis, highly invasive and difficult-to-treat breast cancers accounting for approximately 15% of clinical cases. Given the poor outlook and lack of sustained response to conventional therapies, TNBC has been the subject of intense studies on new therapeutic approaches in recent years. The development of targeted cancer therapies, often in combination with established chemotherapy, has been applied to a number of new clinical studies in this setting in recent years. This review will highlight recent therapeutic advances in TNBC, focusing on small-molecule drugs and their associated biological mechanisms of action, and offering the possibility of improved prospects for this patient group in the near future.

Phosphorylation of αB-crystallin: Role in stress, aging and patho-physiological conditions

BACKGROUND

αB-crystallin, once thought to be a lenticular protein, is ubiquitous and has critical roles in several cellular processes that are modulated by phosphorylation. Serine residues 19, 45 and 59 of αB-crystallin undergo phosphorylation. Phosphorylation of S45 is mediated by p44/42 MAP kinase, whereas S59 phosphorylation is mediated by MAPKAP kinase-2. Pathway involved in S19 phosphorylation is not known.

SCOPE OF REVIEW

The review highlights the role of phosphorylation in (i) oligomeric structure, stability and chaperone activity, (ii) cellular processes such as apoptosis, myogenic differentiation, cell cycle regulation and angiogenesis, and (iii) aging, stress, cardiomyopathy-causing αB-crystallin mutants, and in other diseases.

MAJOR CONCLUSIONS

Depending on the context and extent of phosphorylation, αB-crystallin seems to confer beneficial or deleterious effects. Phosphorylation alters structure, stability, size distribution and dynamics of the oligomeric assembly, thus modulating chaperone activity and various cellular processes. Phosphorylated αB-crystallin has a tendency to partition to the cytoskeleton and hence to the insoluble fraction. Low levels of phosphorylation appear to be protective, while hyperphosphorylation has negative implications. Mutations in αB-crystallin, such as R120G, Q151X and 464delCT, associated with inherited myofibrillar myopathy lead to hyperphosphorylation and intracellular inclusions. An ongoing study in our laboratory with phosphorylation-mimicking mutants indicates that phosphorylation of R120GαB-crystallin increases its propensity to aggregate.

GENERAL SIGNIFICANCE

Phosphorylation of αB-crystallin has dual role that manifests either beneficial or deleterious consequences depending on the extent of phosphorylation and interaction with cytoskeleton. Considering that disease-causing mutants of αB-crystallin are hyperphosphorylated, moderation of phosphorylation may be a useful strategy in disease management. This article is part of a Special Issue entitled Crystallin Biochemistry in Health and Disease.

The Discovery of Novel Biomarkers Improves Breast Cancer Intrinsic Subtype Prediction and Reconciles the Labels in the METABRIC Data Set

BACKGROUND

The prediction of breast cancer intrinsic subtypes has been introduced as a valuable strategy to determine patient diagnosis and prognosis, and therapy response. The PAM50 method, based on the expression levels of 50 genes, uses a single sample predictor model to assign subtype labels to samples. Intrinsic errors reported within this assay demonstrate the challenge of identifying and understanding the breast cancer groups. In this study, we aim to: a) identify novel biomarkers for subtype individuation by exploring the competence of a newly proposed method named CM1 score, and b) apply an ensemble learning, as opposed to the use of a single classifier, for sample subtype assignment. The overarching objective is to improve class prediction.

METHODS AND FINDINGS

The microarray transcriptome data sets used in this study are: the METABRIC breast cancer data recorded for over 2000 patients, and the public integrated source from ROCK database with 1570 samples. We first computed the CM1 score to identify the probes with highly discriminative patterns of expression across samples of each intrinsic subtype. We further assessed the ability of 42 selected probes on assigning correct subtype labels using 24 different classifiers from the Weka software suite. For comparison, the same method was applied on the list of 50 genes from the PAM50 method.

CONCLUSIONS

The CM1 score portrayed 30 novel biomarkers for predicting breast cancer subtypes, with the confirmation of the role of 12 well-established genes. Intrinsic subtypes assigned using the CM1 list and the ensemble of classifiers are more consistent and homogeneous than the original PAM50 labels. The new subtypes show accurate distributions of current clinical markers ER, PR and HER2, and survival curves in the METABRIC and ROCK data sets. Remarkably, the paradoxical attribution of the original labels reinforces the limitations of employing a single sample classifiers to predict breast cancer intrinsic subtypes.

The unfolded protein response in retinal vascular diseases: implications and therapeutic potential beyond protein folding

Angiogenesis is a complex, step-wise process of new vessel formation that is involved in both normal embryonic development as well as postnatal pathological processes, such as cancer, cardiovascular disease, and diabetes. Aberrant blood vessel growth, also known as neovascularization, in the retina and the choroid is a major cause of vision loss in severe eye diseases, such as diabetic retinopathy, age-related macular degeneration, retinopathy of prematurity, and central and branch retinal vein occlusion. Yet, retinal neovascularization is causally and dynamically associated with vasodegeneration, ischemia, and vascular remodeling in retinal tissues. Understanding the mechanisms of retinal neovascularization is an urgent unmet need for developing new treatments for these devastating diseases. Accumulating evidence suggests a vital role for the unfolded protein response (UPR) in regulation of angiogenesis, in part through coordinating the secretion of pro-angiogenic growth factors, such as VEGF, and modulating endothelial cell survival and activity. Herein, we summarize current research in the context of endoplasmic reticulum (ER) stress and UPR signaling in retinal angiogenesis and vascular remodeling, highlighting potential implications of targeting these stress response pathways in the prevention and treatment of retinal vascular diseases that result in visual deficits and blindness.

Alpha B-crystallin correlates with poor survival in colorectal cancer

Alpha B-crystallin (CRYAB) is primarily found as major structural proteins of the ocular lens and is a principal member of the small heat shock protein (HSP) family. So far, CRYAB has been suggested to play critical roles in the development of several kinds of human cancers. However, the association between CRYAB expression and clinicopathological characteristics of colorectal cancer (CRC) has not been elucidated yet. In the present study, one-step quantitative PCR reverse transcription-polymerase chain reaction (qPCR) analysis of 18 samples of CRC and immunohistochemistry (IHC) analysis with 100 cases of CRC sample in tissue microarrays (TMA) were employed to evaluate the expression of CRYAB in CRC. The results suggested that CRYAB expression in the mRNA and protein levels was significantly higher in CRC tissues than in corresponding non-cancerous tissues (P < 0.05 and P = 0.014, respectively). The expression of CRYAB protein in CRC was significantly associated with distant metastasis (P = 0.040) and overall survival (P = 0.003). Kaplan-Meier method and multivariate survival analysis indicated that high expression of CRYAB (P = 0.040) and distant metastasis (P = 0.005) showed significant correlations with poor prognosis of CRC patients. The data imply that CRYAB expression is correlated with substantial clinical characteristics of CRC, and it may be identified as an unfavorable prognostic factor for CRC.

Glioblastoma-associated stromal cells (GASCs) from histologically normal surgical margins have a myofibroblast phenotype and angiogenic properties

Glioblastoma (GB) displays diffusely infiltrative growth patterns. Dispersive cells escape surgical resection and contribute to tumour recurrence within a few centimeters of the resection cavity in 90% of cases. We know that the non-neoplastic stromal compartment, in addition to infiltrative tumour cells, plays an active role in tumour recurrence. We isolated a new stromal cell population from the histologically normal surgical margins of GB by computer-guided stereotaxic biopsies and primary culture. These GB-associated stromal cells (GASCs) share phenotypic and functional properties with the cancer-associated fibroblasts (CAFs) described in the stroma of carcinomas. In particular, GASCs have tumour-promoting effects on glioma cells in vitro and in vivo. Here, we describe a quantitative proteomic analysis, using iTRAQ labelling and mass spectrometry, to compare GASCs with control stromal cells derived from non-GB peripheral brain tissues. A total of 1077 proteins were quantified and 67 proteins were found to differ between GASCs and control stromal cells. Several proteins changed in GASCs are related to a highly motile myofibroblast phenotype, and to wound healing and angiogenesis. The results for several selected proteins were validated by western blotting or flow cytometry. Furthermore, the effect of GASCs on angiogenesis was confirmed using the orthotopic U87MG glioma model. In conclusion, GASCs, isolated from GB histologically normal surgical margins and found mostly near blood vessels, could be a vascular niche constituent establishing a permissive environment, facilitating angiogenesis and possibly colonization of recurrence-initiating cells. We identify various proteins as being expressed in GASCs: some of these proteins may serve as prognostic factors for GB and/or targets for anti-glioma treatment.

The effect of donor variation and senescence on endothelial differentiation of human mesenchymal stromal cells

Application of autologous cells is considered for a broad range of regenerative therapies because it is not surrounded by the immunological and ethical issues of allo- or xenogenic cells. However, isolation, expansion, and application of autologous cells do suffer from variability in therapeutic efficacy due to donor to donor differences and due to prolonged culture. One important source of autologous cells is mesenchymal stromal cells (MSCs), which can differentiate toward endothelial-like cells, thus making them an ideal candidate as cell source for tissue vascularization. Here we screened MSCs from 20 donors for their endothelial differentiation capacity and correlated it with the gene expression profile of the whole genome in the undifferentiated state. Cells of all donors were able to form tubes on Matrigel and induced the expression of endothelial genes, although with quantitative differences. In addition, we analyzed the effect of prolonged in vitro expansion on the multipotency of human MSCs and found that endothelial differentiation is only mildly sensitive to expansion-induced loss of differentiation as compared to osteogenic and adipogenic differentiation. Our results show the robustness of the endothelial differentiation protocol and the gene expression data give insight in the differences in endothelial differentiation between donors.

Differential expression and regulation of Cryab in mouse uterus during preimplantation period

The aim of this study was to examine the expression and regulation of the crystallin, alpha B (Cryab) gene in mouse uterus during the peri-implantation period by in situ hybridization and real-time PCR. There was no detectable Cryab mRNA signal on days 1-4 of pregnancy. On day 5 of pregnancy when embryo implanted, a high level of Cryab mRNA signal was found in the subluminal stroma surrounding the implanting blastocyst. On days 6-8, Cryab mRNA was strongly expressed in the primary decidua. By real-time PCR, a high level of Cryab expression was detected on days 7 and 8 of pregnancy, although Cryab expression was seen from days 1 to 8. Under in vivo and in vitro artificial decidualization, Cryab expression was significantly elevated. Compared with the progesterone-primed delayed implantation uterus, a high level of Cryab mRNA expression was observed in estrogen-activated implantation uterus. In the uterine stromal cells, cAMP, estrogen, and progesterone could induce the expression of Cryab gene. In the ovariectomized mouse uterus, estrogen could also induce the expression of Cryab while progesterone inhibited its expression. Our data suggest that Cryab may play an important role during mouse embryo implantation and decidualization and that estrogen and progesterone can regulate the expression of Cryab gene.

Connection of pericyte-angiopoietin-Tie-2 system in diabetic retinopathy: friend or foe?

Pericytes are distinctive regulators of vascular morphologenesis and function during vascular development and homeostasis. Pericytes have recently come into focus as implications of aberrant interactions between pericytes and endothelial cells in number of pathological angiogenesis conditions, including diabetic retinopathy and tumor angiogenesis. Pericyte dropout is a hallmark of early diabetic retinopathy. Abnormal angiopoietin (Ang)-Tie-2 signaling is one principal system participating in pericyte/endothelial cell dissociation during early stages of diabetic retinopathy. Angiopoietin 2 (Ang-2) is among the relevant growth factors induced by hypoxia and plays an important role in the initiation of retinal neovascularization and cause pericyte loss. Furthermore, high levels of VEGF synergize Ang-Tie-2 signaling during the development of diabetic retinopathy. An accelerated rate of clinical development Ang-Tie-2-manipulating drugs requests a better mechanistic understanding the connection between pericytes and Ang-Tie-2 systems both under normal and disease conditions. We summarize recent advances in pericyte study in conjunction with Ang-Tie-2 signaling and also discuss possible therapeutic strategies for diabetic retinopathy by targeting pericytes through manipulating Ang-Tie-2 signaling.

Role of α-crystallin B as a regulatory switch in modulating cardiomyocyte apoptosis by mitochondria or endoplasmic reticulum during cardiac hypertrophy and myocardial infarction

Cardiac hypertrophy and myocardial infarction (MI) are two major causes of heart failure with different etiologies. However, the molecular mechanisms associated with these two diseases are not yet fully understood. So, this study was designed to decipher the process of cardiomyocyte apoptosis during cardiac hypertrophy and MI in vivo. Our study revealed that mitochondrial outer membrane channel protein voltage-dependent anion channel-1 (VDAC1) was upregulated exclusively during cardiac hypertrophy, whereas 78 kDa glucose-regulated protein (GRP78) was exclusively upregulated during MI, which is an important upstream regulator of the endoplasmic reticulum (ER) stress pathway. Further downstream analysis revealed that mitochondrial pathway of apoptosis is instrumental in case of hypertrophy, whereas ER stress-induced apoptosis is predominant during MI, which was confirmed by treatment with either siRNA against VDAC1 or ER stress inhibitor tauroursodeoxycholic acid (TUDCA). Very interestingly, our data also showed that the expression and interaction of small heat-shock protein α-crystallin B (CRYAB) with VDAC1 was much more pronounced during MI compared with either hypertrophy or control. The study demonstrated for the first time that two different organelles—mitochondria and ER have predominant roles in mediating cardiomyocyte death signaling during hypertrophy and MI, respectively, and activation of CRYAB acts as a molecular switch in bypassing mitochondrial pathway of apoptosis during MI.

αB-crystallin stimulates VEGF secretion and tumor cell migration and correlates with enhanced distant metastasis in head and neck squamous cell carcinoma

Background

αB-crystallin is able to modulate vascular endothelial growth factor (VEGF) secretion. In many solid tumors VEGF is associated with angiogenesis, metastasis formation and poor prognosis. We set out to assess whether αB-crystallin expression is correlated with worse prognosis and whether this is related to VEGF secretion and cell motility in head and neck squamous cell carcinoma (HNSCC).

Methods

αB-crystallin expression was determined immunohistochemically in tumor biopsies of 38 HNSCC patients. Locoregional control (LRC) and metastasis-free survival (MFS) of the patients were analyzed in relation to αB-crystallin expression. Additionally, the effects of αB-crystallin knockdown on VEGF secretion and cell motility were studied in vitro.

Results

Patients with higher staining fractions of αB-crystallin exhibited a significantly shorter MFS (Log-Rank test, p < 0.005). Under normoxic conditions αB-crystallin knockdown with two different siRNAs in a HNSCC cell line reduced VEGF secretion 1.9-fold and 2.1-fold, respectively. Under hypoxic conditions, a similar reduction of VEGF secretion was observed, 1.9-fold and 2.2-fold, respectively. The effect on cell motility was assessed by a gap closure assay, which showed that αB-crystallin knockdown decreased the rate by which HNSCC cells were able to close a gap by 1.5- to 2.0-fold.

Conclusions

Our data suggest that αB-crystallin expression is associated with distant metastases formation in HNSCC patients. This association might relate to the chaperone function of αB-crystallin in mediating folding and secretion of VEGF and stimulating cell migration.

Targeting the IRE1α/XBP1 and ATF6 arms of the unfolded protein response enhances VEGF blockade to prevent retinal and choroidal neovascularization

Although anti-vascular endothelial growth factor (VEGF) treatments reduce pathological neovascularization in the eye and in tumors, the regression is often not sustainable or is incomplete. We investigated whether vascular endothelial cells circumvent anti-VEGF therapies by activating the unfolded protein response (UPR) to override the classic extracellular VEGF pathway. Exposure of endothelial cells to VEGF, high glucose, or H2O2 up-regulated the X-box binding protein-1/inositol-requiring protein-1 (IRE1) α and activating transcription factor 6 (ATF6) arms of the UPR compared with untreated cells. This was associated with increased expression in α-basic crystallin (CRYAB), which has previously bound VEGF. siRNA knockdown or pharmacological blockade of IRE1α, ATF6, or CRYAB increased intracellular VEGF degradation and decreased full-length intracellular VEGF. Inhibition of IRE1α, ATF6, or CRYAB resulted in an approximately 40% reduction of in vitro angiogenesis, which was further reduced in combination with a neutralizing antibody against extracellular VEGF. Blockade of IRE1α or ATF6 in the oxygen-induced retinopathy or choroidal neovascularization mouse models caused an approximately 35% reduction in angiogenesis. However, combination therapy of VEGF neutralizing antibody with UPR inhibitors or siRNAs reduced retinal/choroidal neovascularization by a further 25% to 40%, and this inhibition was significantly greater than either treatment alone. In conclusion, activation of the UPR sustains angiogenesis by preventing degradation of intracellular VEGF. The IRE1α/ATF6 arms of the UPR offer a potential therapeutic target in the treatment of pathological angiogenesis.

αB-Crystallin regulates expansion of CD11b⁺Gr-1⁺ immature myeloid cells during tumor progression

The molecular chaperone αB-crystallin has emerged as a target for cancer therapy due to its expression in human tumors and its role in regulating tumor angiogenesis. αB-crystallin also reduces neuroinflammation, but its role in other inflammatory conditions has not been investigated. Here, we examined whether αB-crystallin regulates inflammation associated with tumors and ischemia. We found that CD45(+) leukocyte infiltration is 3-fold increased in tumors and ischemic myocardium in αB-crystallin-deficient mice. Notably, αB-crystallin is prominently expressed in CD11b(+) Gr-1(+) immature myeloid cells (IMCs), known as regulators of angiogenesis and immune responses, while lymphocytes and mature granulocytes show low αB-crystallin expression. αB-Crystallin deficiency results in a 3-fold higher accumulation of CD11b(+) Gr-1(+) IMCs in tumors and a significant rise in CD11b(+) Gr-1(+) IMCs in spleen and bone marrow. Similarly, we noted a 2-fold increase in CD11b(+) Gr-1(+) IMCs in chronically inflamed livers in αB-crystallin-deficient mice. The effect of αB-crystallin on IMC accumulation is limited to pathological conditions, as CD11b(+) Gr-1(+) IMCs are not elevated in naive mice. Through ex vivo differentiation of CD11b(+) Gr-1(+) cells, we provide evidence that αB-crystallin regulates systemic expansion of IMCs through a cell-intrinsic mechanism. Our study suggests a key role of αB-crystallin in limiting expansion of CD11b(+) Gr-1(+) IMCs in diverse pathological conditions.

Development of an anti-angiogenic therapeutic model combining scAAV2-delivered siRNAs and noninvasive photoacoustic imaging of tumor vasculature development

We aimed to develop an anti-angiogenic model for breast cancer by combining (1) siRNA-based therapy delivered by self-complementary adeno-associated virus serotype 2 (scAAV2) vectors to target tumor vasculature, and (2) noninvasive monitoring to tumor response to anti-angiogenesis by photoacoustic (PA) imaging. scAAV2 vector containing 7 surface exposed tyrosine to phenylanine capsid mutations was able to transduce microvascular endothelial cells with high efficiency. siRNAs against UPR (unfolded protein response)-IRE1α, XBP-1, ATF6 significantly inhibited breast cancer-induced angiogenesis in vitro by inhibiting endothelial cell survival. PA imaging showed that knockdown of UPR proteins greatly reduced tumor angiogenesis in vivo in breast cancer models.

Deficiency of αB crystallin augments ER stress-induced apoptosis by enhancing mitochondrial dysfunction

Endoplasmic reticulum (ER) stress is linked to several pathological conditions including age-related macular degeneration. Excessive ER stress initiates cell death cascades which are mediated, in part, through mitochondrial dysfunction. Here, we identify αB crystallin as an important regulator of ER stress-induced cell death. Retinal pigment epithelial (RPE) cells from αB crystallin (-/-) mice, and human RPE cells transfected with αB crystallin siRNA, are more vulnerable to ER stress induced by tunicamycin. ER stress-mediated cell death is associated with increased levels of reactive oxygen species, depletion of glutathione in mitochondria, decreased superoxide dismutase activity, increased release of cytochrome c, and activation of caspases 3 and 4. The ER stress signaling inhibitors, salubrinal and 4-(2-aminoethyl) benzenesulfonyl fluoride, decrease mitochondrial damage and reduce RPE apoptosis induced by ER stress. Prolonged ER stress decreases levels of αB crystallin, thus exacerbating mitochondrial dysfunction. Overexpression of αB crystallin protects RPE cells from ER stress-induced apoptosis by attenuating increases in Bax, CHOP, mitochondrial permeability transition, and cleaved caspase 3. Thus, these data collectively demonstrate that αB crystallin provides critical protection of mitochondrial function during ER stress-induced RPE apoptosis.

Novel roles for α-crystallins in retinal function and disease

α-Crystallins are key members of the superfamily of small heat shock proteins that have been studied in detail in the ocular lens. Recently, novel functions for α-crystallins have been identified in the retina and in the retinal pigmented epithelium (RPE). αB-Crystallin has been localized to multiple compartments and organelles including mitochondria, golgi apparatus, endoplasmic reticulum and nucleus. α-Crystallins are regulated by oxidative and endoplasmic reticulum stress, and inhibit apoptosis-induced cell death. α-Crystallins interact with a large number of proteins that include other crystallins, and apoptotic, cytoskeletal, inflammatory, signaling, angiogenic, and growth factor molecules. Studies with RPE from αB-crystallin deficient mice have shown that αB-crystallin supports retinal and choroidal angiogenesis through its interaction with vascular endothelial growth factor. αB-Crystallin has also been shown to have novel functions in the extracellular space. In RPE, αB-crystallin is released from the apical surface in exosomes where it accumulates in the interphotoreceptor matrix and may function to protect neighboring cells. In other systems administration of exogenous recombinant αB-crystallin has been shown to be anti-inflammatory. Another newly described function of αB-crystallin is its ability to inhibit β-amyloid fibril formation. α-Crystallin minichaperone peptides have been identified that elicit anti-apoptotic function in addition to being efficient chaperones. Generation of liposomal particles and other modes of nanoencapsulation of these minipeptides could offer great therapeutic advantage in ocular delivery for a wide variety of retinal degenerative, inflammatory and vascular diseases including age-related macular degeneration and diabetic retinopathy.