Stanniocalcin 1 is important for poststroke functionality, but dispensable for ischemic tolerance

Subconjunctival Administration of an Adeno-Associated Virus Expressing Stanniocalcin-1 Provides Sustained Intraocular Pressure Reduction in Mice

Purpose

To investigate subconjunctival administration of a single-stranded, adeno-associated virus, serotype 2, engineered to express stanniocalcin-1 with a FLAG tag (ssAAV2-STC-1-FLAG) as a novel sustained (IOP) lowering agent with a reduced ocular surface side effect profile.

Design

In vivo preclinical investigation in mice.

Subjects

C57BL/6J, DBA/2J, prostaglandin F (FP) receptor knockout mice.

Methods

Normotensive C57BL/6J mice were treated with a subconjunctival injection of ssAAV2-STC-1-FLAG (2 μL; 6 × 109 viral genomes [VGs]) in 1 eye and the same volume and concentration of ssAAV2-green fluorescent protein (GFP) or the same volume of phosphate-buffered saline in the fellow eye. Ocular hypertensive DBA/2J mice were subconjunctivally injected with 6 × 109 VGs of ssAAV2-STC-1-FLAG or ssAAV2-GFP. Steroid-mediated ocular hypertension was induced in C57BL/6J mice with weekly injections of dexamethasone into the conjunctival fornix, and mice were then injected subconjunctivally with 6 × 109 VGs of ssAAV2-STC-1-FLAG or ssAAV2-GFP. Prostaglandin F receptor knockout mice were injected subconjunctivally with 6 × 109 VGs of ssAAV2-STC-1-FLAG or phosphate-buffered saline. An identical vector was constructed without the FLAG tag (ssAAV2-STC-1) and evaluated in normotensive C57BL/6J mice. Intraocular pressure was assessed using the Tonolab tonometer for all experiments. Tumor necrosis factor alpha (TNFα), a marker of ocular surface inflammation, was compared between subconjunctivally delivered ssAAV2-STC-1-FLAG and other treatments including daily topical latanoprost.

Main Outcome Measures

Intraocular pressure assessment.

Results

Subconjunctival delivery of ssAAV2-STC-1-FLAG significantly reduced IOP for 10 weeks post injection in normotensive mice. Maximal IOP reduction was seen at week 3 postinjection (17.4%; 17.1 ± 0.8 vs. 14.1 ± 0.8 mmHg, P < 0.001). After the IOP-lowering effect had waned, a second injection restored the ocular hypotensive effect. Subconjunctivally delivered ssAAV2-STC-1-FLAG lowered IOP in DBA/2J mice (16.9%; 17.8 ± 2.0 vs. 14.8 ± 0.9 mmHg, P < 0.001) and steroid-mediated ocular hypertensive mice (20.0%; 19.0 ± 0.6 vs. 15.2 ± 0.7 mmHg, P < 0.001) over the experimental period. This construct also reduced IOP to a similar extent in wild-type (15.9%) and FP receptor knockout (15.7%) mice compared with the fellow eye. A related construct also lowered IOP without the FLAG tag in a similar manner. Reduction in conjunctival TNFα was seen when comparing subconjunctivally delivered ssAAV2-STC-1-FLAG to daily topical latanoprost.

Conclusions

Subconjunctival delivery of the STC-1 transgene with a vector system may represent a novel treatment strategy for sustained IOP reduction and improved ocular tolerability that also avoids the daily dosing requirements of currently available medications.

Financial Disclosures

Proprietary or commercial disclosure may be found in the Footnotes and Disclosures at the end of this article.

A Prospective Longitudinal Cohort Study of Serum Stanniocalcin-1 as a Potential Prognostic Biomarker of Severe Traumatic Brain Injury

Background

Stanniocalcin-1 (STC1) may harbor anti-inflammatory and anti-oxidative properties, thereby exerting neuroprotective effects. This study was done with the intent to determine the role of serum STC1 in severity assessment and prognosis prediction of severe traumatic brain injury (sTBI).

Methods

In this prospective longitudinal cohort study of 104 sTBI patients and 104 healthy individuals (controls), serum STC1 levels were quantified. Severity indicators were Glasgow Coma Scale (GCS) and Rotterdam computed tomography classification. Follow-up time was 180 days and extended Glasgow outcome scale (GOSE) score 1-4 was deemed as poor prognosis. Multivariate analyses were applied to assess severity correlations and prognosis associations. Discriminative efficiencies were estimated in terms of area under receiver operating characteristic curve (AUC).

Results

Patients exhibited significantly higher serum STC1 levels than controls. Serum STC1 levels were substantially elevated in order of GCS scores from 8 to 3, Rotterdam scores from 3 to 6 and 180-day GOSE scores from 8 to 1. Also, serum STC1 levels were independently correlated with GCS scores, Rotterdam scores and 180-day GOSE scores. Serum STC1 levels were independently associated with 180-day death, overall survival and poor prognosis, as well as were efficiently predictive of death and poor prognosis. Prediction model containing GCS scores, Rotterdam scores and serum STC1 levels, as opposed to any of them, showed higher discriminative ability for the risks of death and poor prognosis. Alternatively, serum STC1 levels were linearly correlated with risk of death, overall survival and poor prognosis under restricted cubic spline. Subgroup analysis showed that serum STC1 levels non-statistically significantly interacted with age, gender, hypertension, diabetes mellitus, etc.

Conclusion

A significant elevation of serum STC1 levels is highly related to severity and clinical outcome, suggesting that serum STC1 may be a potential prognostic biomarker of sTBI.

Patent highlights August-September 2023

A snapshot of noteworthy recent developments in the patent literature of relevance to pharmaceutical and medical research and development.

Serum Olink Proteomics-Based Identification of Protein Biomarkers Associated with the Immune Response in Ischemic Stroke

The immune response is considered essential for pathology of ischemic stroke (IS), but it remains unclear which immune response-related proteins exhibit altered expression in IS patients. Here, we used Olink proteomics to examine the expression levels of 92 immune response-related proteins in the sera of IS patients (n = 88) and controls (n = 88), and we found that 59 of these proteins were differentially expressed. Feature variables were screened from the differentially expressed proteins by the least absolute shrinkage and selection operator (LASSO) and the random forest and by determining whether their proteins had an area under the curve (AUC) greater than 0.8. Ultimately, we identified six potential protein biomarkers of IS, namely, MASP1, STC1, HCLS1, CLEC4D, PTH1R, and PIK3AP1, and established a logistic regression model that used these proteins to diagnose IS. The AUCs of the models in the internal validation and the test set were 0.962 (95% confidence interval (CI): 0.895-1.000) and 0.954 (95% CI: 0.884-1.000), respectively, and the same protein detection method was performed in an external independent validation set (AUC: 0.857 (95% CI: 0.801-0.913)). These proteins may play a role in immune regulation via the C-type lectin receptor signaling pathway, the PI3K-AKT signaling pathway, and the B-cell receptor signaling pathway.

Usability of Serum Stanniocalcin-1 as a Prognostic Biochemical Marker of Acute Supratentorial Intracerebral Hemorrhage: A Prospective Cohort Study

Objective

Stanniocalcin-1 (STC1) may be neuroprotective. This study aimed to evaluate the prognostic role of serum STC1 levels in intracerebral hemorrhage (ICH).

Methods

This prospective observational study was assigned in two parts. In the first part, blood samples of 48 patients with ICH were acquired on admission and on days 1, 2, 3, 5, and 7 after ICH, and those of 48 controls were collected at their entry into the study. In the second part, blood samples of 141 patients with ICH were obtained upon admission. Serum STC1 levels were measured, and the National Institutes of Health Stroke Scale (NIHSS), hematoma volume, and poststroke 6-month modified Rankin Scale (mRS) scores were recorded. Dynamic changes in serum STC levels and their correlation with disease severity and prognosis were investigated.

Results

Serum STC1 levels were elevated after ICH, peaked on day 1, plateaued on day 2, declined gradually afterwards, and were significantly higher than those in controls. Serum STC1 levels were independently correlated with NIHSS scores, hematoma volume, and the 6-month post-injury mRS scores. Serum STC1 levels, NIHSS scores, and hematoma volume independently predicted a poor prognosis (mRS scores of 3-6). The model integrating serum STC1 levels, NIHSS scores, and hematoma volume was visually displayed using a nomogram and was relatively stable using the Hosmer-Lemeshow test and calibration curve analysis. Under the receiver operating characteristic curve, serum STC1 levels efficiently predicted a poor prognosis and showed similar prognostic ability to NIHSS scores and hematoma volume. The preceding model had significantly higher prognostic capability than NIHSS scores and hematoma volume alone and their combination.

Conclusion

Substantial enhancement of serum STC1 levels after ICH, which is strongly correlated with severity, independently distinguished the risk of poor prognosis, assuming that serum STC1, as a prognostic parameter, may be clinically valuable in ICH.

Intravitreal Administration of Stanniocalcin-1 Rescues Photoreceptor Degeneration with Reduced Oxidative Stress and Inflammation in a Porcine Model of Retinitis Pigmentosa

PURPOSE

To investigate the effect of stanniocalcin-1 (STC-1), a secreted polypeptide exhibiting multiple functions in cell survival and death, on photoreceptor degeneration in a porcine model of retinitis pigmentosa (RP).

METHODS

P23H transgenic pigs (TG P23H) and wild-type hybrid littermates were obtained from the National Swine Resource and Research Center. Human recombinant STC-1 was injected intravitreally every 2 weeks from postnatal day 15 (P15) to P75. The contralateral eye was injected with balanced salt solution as a control. Electroretinography (ERG) and spectral domain optical coherence tomography (SD-OCT) were performed to evaluate retinal function and morphology in vivo at P90. Retinal tissue was collected for histologic analysis and molecular assays to evaluate the antioxidative and anti-inflammatory mechanisms by which STC-1 may rescue photoreceptor degeneration.

RESULTS

Intravitreal injection of STC-1 improved retinal function in TG P23H pigs with increased photopic and flicker ERG a- and b-wave amplitudes. Greater integrity of the ellipsoid zone (EZ) band on SD-OCT and morphologic rescue with preservation of cone photoreceptors were observed in STC-1-treated TG P23H pigs. STC-1 altered gene expression in TG P23H pig retina on microarray analysis and increased photoreceptor specific gene expression by reverse transcription-polymerase chain reaction analysis. STC-1 significantly decreased oxidative stress and the expressions of NLRP3 inflammasome, cleaved caspase-1, and IL-1β in TG P23H pig retina.

CONCLUSIONS

Intravitreal administration of STC-1 enhances cone photoreceptor function, improves EZ integrity, and reduces retinal degeneration through antioxidative and anti-inflammatory effects in a large animal (pig) model of the most common form of autosomal dominant RP in the United States.

Transgene expression of Stanniocalcin-1 provides sustained intraocular pressure reduction by increasing outflow facility

Glaucoma is the leading cause of irreversible blindness worldwide. Therapies for glaucoma are directed toward reducing intraocular pressure (IOP), the leading risk factor and only reliable therapeutic target via topical medications or with procedural intervention including laser or surgery. Though topical therapeutics are typically first line, less than 50% of patients take drops as prescribed. Sustained release technologies that decrease IOP for extended periods of time are being examined for clinical use. We recently identified Stanniocalcin-1, a naturally occurring hormone, as an IOP-lowering agent. Here, we show that a single injection into the anterior chamber of mice with an adeno-associated viral vector containing the transgene of stanniocalcin-1 results in diffuse and sustained expression of the protein and produces IOP reduction for up to 6 months. As the treatment effect begins to wane, IOP-lowering can be rescued with a repeat injection. Aqueous humor dynamic studies revealed an increase in outflow facility as the mechanism of action. This first-in-class therapeutic approach has the potential to improve care and reduce the rates of vision loss in the 80 million people worldwide currently affected by glaucoma.

Early-stage serum Stanniocalcin 1 as a predictor of outcome in patients with aneurysmal subarachnoid hemorrhage

Stanniocalcin-1 (STC1) takes part in anti-inflammatory and anti-oxidative processes, thus demonstrating neuroprotective properties. Early brain injuries associated with initial subarachnoid hemorrhage typically led to secondary cerebral infarction and poor outcomes. This retrospective study aimed to clarify the clinical significance of serum STC1 level in patients with subarachnoid hemorrhage.We collected demographic information, comorbidities, neurological status in detail. All blood samples were collected on admission. Enzyme-linked immunosorbent assay kits were used to detect the serum level of STC1. Spearman analysis was used to explore the relationship between STC1 and clinical severity. Multivariate logistic regression was used to investigate the prognostic role of STC1 in patients with aneurysmal subarachnoid hemorrhage (aSAH). Receiver operating characteristic curve was performed to investigate the power of STC1 in predicting outcome in aSAH patients.Serum STC1 concentration was significantly higher in aSAH patients than in healthy individuals. Serum concentration of STC1 positively correlated with Hunt-Hess grade (r = 0.62, P < .01) and Fisher grade (r = 0.48, P < .01), and negatively correlated with Glasgow Coma Scale on admission (r = -0.45, P < .01). Patients with delayed cerebral ischemia (DCI) had higher level of serum STC1 than those without DCI (13.12 ± 1.44 vs 8.56 ± 0.31, P < .01). Moreover, patients with poor outcome had higher concentration of STC1 than patients with good outcome (11.82 ± 0.62 vs 8.21 ± 0.35,P < 0.01). Results of univariate and multivariate logistic analysis revealed that Hunt-hess III-IV, DCI, and high STC1 level were independent risk factors associated with poor outcome of patients with aSAH. Further analysis revealed that combination of STC1 with Hunt-hess grade was more superior to 2 indicators alone in predicting clinical outcome of aSAH patients.STC1 can be used as a novel biomarker in predicting outcome of patients with aSAH, especially when combined with Hunt-hess grade.

Stanniocalcin-1 Reduced Intraocular Pressure in Two Models of Ocular Hypertension

Purpose/Aim: Glaucomatous optic neuropathy (GON) remains the world's leading cause of irreversible blindness. Treatments including topical medications are directed at reducing intraocular pressure (IOP), the most significant risk factor for GON. Current medications, while generally effective, are limited by insufficient response and side-effects in some patients. In search of a more targeted therapy that acts downstream of existing medications that has a potential for a lower side effect profile, our laboratory has identified Stanniocalcin-1 (STC-1), a multifunctional hormone, as an effector molecule in latanoprost-mediated IOP reduction with similar IOP-lowering efficacy as latanoprost in normotensive mice.Materials and methods: To investigate whether STC-1 can also reduce IOP in ocular hypertensive mice, we used a steroid-induced ocular hypertensive mouse model characterized by trabecular meshwork dysfunction as well as the DBA/2J mouse as an inherited model of pigment dispersion and secondary angle closure. Steroid-induced ocular hypertension was induced by weekly injections of dexamethasone into the conjunctival fornix of wild-type C57BL/6J mice (6-8 months old). After confirmation of the steroid response, mice were administered STC-1 or phosphate buffered saline (PBS) topically once daily for six weeks. For DBA/2J mice (14 months old), after baseline IOP measurements, mice were treated topically once daily with STC-1 or PBS for 5 days and IOP was assessed twice daily.Results: In steroid-induced ocular hypertensive mice, STC-1 lowered IOP by 26% (P < .001, week three) and maintained this level of IOP reduction throughout the remainder of the treatment period (P < .001, week six). In DBA/2J mice, STC-1 lowered IOP by 37% (P < .001).Conclusions: Together, these data show that STC-1 reduced IOP in two models of ocular hypertension with different mechanisms of outflow obstruction.

STC1 ameliorates cognitive impairment and neuroinflammation of Alzheimer's disease mice via inhibition of ERK1/2 pathway

OBJECTIVE

To investigate the regulatory role of STC1 (Stanniocalcin-1) mediated ERK1/2 pathway in cognitive impairment and neuroinflammation of Alzheimer's disease (AD).

METHODS

WT mice and STC1 Tg mice (transgenic overexpression of STC1) were used to establish AD models to perform behavioral test by Morris water maze. Hippocampal cell apoptosis was quantified by TUNEL staining, the levels of inflammatory cytokines in serum and hippocampal tissues determined by ELISA, as well as oxidative stress-related factors detected by corresponding testing kits, and protein expression of STC1 and ERK1/2 pathway measured by Western blotting.

RESULTS

Compared with WT Sham group, WT AD mice had prolonged escape latency, decreased crossing platform times, increased hippocampal cell apoptosis with up-regulated inflammatory cytokines and oxidative stress-related factors, as well as increased STC1 and ERK1/2 pathway-related molecules. By contrast, STC1 Tg AD mice showed shortened escape latency, increased crossing platform times than WT AD mice, and they also exhibited the decreased apoptosis index and inflammatory cytokines, alleviated oxidative stress-injury, down-regulated protein expression of ERK1/2 pathway, and up-regulated the protein expression of STC1 and UCP2.

CONCLUSION

STC1 overexpression could alleviate oxidative stress-induced injury, reduce neuroinflammation, improve cognitive function to play a neuro-protective role by inhibiting ERK1/2 signaling pathway.

Stanniocalcin 1 Inhibits the Inflammatory Response in Microglia and Protects Against Sepsis-Associated Encephalopathy

Sepsis-associated encephalopathy is a serious consequence of sepsis, triggered by the host response against an infectious agent, that can lead to brain damage and cognitive impairment. Several mechanisms have been proposed in this bidirectional communication between the immune system and the brain after sepsis as neuroinflammation, oxidative stress, and mitochondrial dysfunction. Stanniocalcin-1 (STC-1), an endogen neuroprotective protein, acts as an anti-inflammatory and suppresses superoxide generation through induction of uncoupling proteins (UCPs) in the mitochondria. Here, we demonstrated a protective role of STC-1 on inflammatory responses in vitro, in activated microglia stimulated with LPS, and on neuroinflammation, oxidative stress, and mitochondrial function in the hippocampus of rats subjected to an animal model of sepsis by cecal ligation and puncture (CLP), as well the consequences on long-term memory. Recombinant human STC-1 (rhSTC1) suppressed the pro-inflammatory cytokine production in LPS-stimulated microglia without changing the UCP-2 expression. Besides, rhSTC1 injected into the cisterna magna decreased acute hippocampal inflammation and oxidative stress and increased the activity of complex I and II activity of mitochondrial respiratory chain and creatine kinase at 24 h after sepsis. rhSTC1 was effective in preventing long-term cognitive impairment after CLP. In conclusion, rhSTC1 confers significant neuroprotection by inhibiting the inflammatory response in microglia and protecting against sepsis-associated encephalopathy in rats.

Pathophysiology of Blood-Brain Barrier Permeability Throughout the Different Stages of Ischemic Stroke and Its Implication on Hemorrhagic Transformation and Recovery

The blood-brain barrier (BBB) is a dynamic interface responsible for maintaining the central nervous system homeostasis. Its unique characteristics allow protecting the brain from unwanted compounds, but its impairment is involved in a vast number of pathological conditions. Disruption of the BBB and increase in its permeability are key in the development of several neurological diseases and have been extensively studied in stroke. Ischemic stroke is the most prevalent type of stroke and is characterized by a myriad of pathological events triggered by an arterial occlusion that can eventually lead to fatal outcomes such as hemorrhagic transformation (HT). BBB permeability seems to follow a multiphasic pattern throughout the different stroke stages that have been associated with distinct biological substrates. In the hyperacute stage, sudden hypoxia damages the BBB, leading to cytotoxic edema and increased permeability; in the acute stage, the neuroinflammatory response aggravates the BBB injury, leading to higher permeability and a consequent risk of HT that can be motivated by reperfusion therapy; in the subacute stage (1-3 weeks), repair mechanisms take place, especially neoangiogenesis. Immature vessels show leaky BBB, but this permeability has been associated with improved clinical recovery. In the chronic stage (>6 weeks), an increase of BBB restoration factors leads the barrier to start decreasing its permeability. Nonetheless, permeability will persist to some degree several weeks after injury. Understanding the mechanisms behind BBB dysregulation and HT pathophysiology could potentially help guide acute stroke care decisions and the development of new therapeutic targets; however, effective translation into clinical practice is still lacking. In this review, we will address the different pathological and physiological repair mechanisms involved in BBB permeability through the different stages of ischemic stroke and their role in the development of HT and stroke recovery.

Oxidative Stress Markers and the Retinopathy of Prematurity

Retinopathy of prematurity (ROP) is a leading cause of potentially preventable blindness in low birth weight preterm infants. Several perinatal and postnatal factors contribute to the incomplete maturation of retinal vascularization, leading to oxidative stress damage. Literature data suggest that the lack of equilibrium between pro-oxidants and anti-oxidants plays a key role. In the last decade, there has been an increasing interest in identifying the antecedents of ROP and the relevant pathogenic mechanisms involved. In this context, a panel of biomarkers was investigated in order to achieve early detection of oxidative stress occurrence and to prevent retinal damage. Several nutritional elements have been found to play a relevant role in ROP prevention. At this stage, no conclusive data have been shown to support the usefulness of one biomarker over another. Recently, the Food and Drugs Administration, the European Medicine Agency, and the National Institute of Health proposed a series of criteria in order to promote the inclusion of new biomarkers in perinatal clinical guidelines and daily practice. The aim of the present review is to offer an update on a panel of biomarkers, currently investigated as potential predictors of ROP, highlighting their strengths and weaknesses.

Stanniocalcin 1 is a prognostic biomarker in glioma

Malignant gliomas are the most common type of primary malignancy of the central nervous system with a poor prognosis. Stanniocalcin 1 (STC1) is closely associated with tumor genesis and development. However, its role in the development and progression of glioma is poorly understood. In silico analysis, The Cancer Genome Atlas (TCGA), Chinese Glioma Genome Atlas (CGGA), Rembrandt and GSE16011 datasets were used to assess the expression levels of STC1 in non-tumor brain tissues and gliomas. Moreover, reverse transcription-quantitative PCR and immunohistochemistry were used to detect STC1 expression in tumor tissues collected in the Department of Neurosurgery of Shenzhen People's Hospital (Shenzhen, China). The association between STC1 expression and different molecular pathological features was analyzed in four public datasets, as well as via Kaplan-Meier analysis. Furthermore, normalized mRNA expression in TCGA was used to perform Gene Ontology analysis. It was revealed that STC1 expression was significantly elevated in glioma tissues compared with the non-tumor brain tissues, both in silico analysis and via cohort validation. According to TCGA, CGGA, Rembrandt and GSE16011 datasets, it was identified that STC1 expression was increased in high grade glioma compared with low grade glioma. In addition, the results indicated STC1 expression was enriched in the isocitrate dehydrogenase (IDH) wild-type and mesenchymal subtype in TCGA, GSE16011 and Rembrandt datasets. Moreover, it was demonstrated that patients with higher STC1 expression exhibited shorter overall survival times compared with those with lower STC1 expression using Kaplan-Meier analysis, according to both the public datasets and validation cohort. Furthermore, the results of the Gene Ontology analysis demonstrated that STC1 was primarily involved in the reorganization of extracellular matrix and was significantly correlated with invasive-related proteins. Therefore, the present results indicate that STC1 was upregulated in glioma tissues and may represent a prognostic biomarker in patients with glioma.

Expression, function and clinical application of stanniocalcin-1 in cancer

The glycoprotein stanniocalcin-1 functions as a regulatory endocrine hormone that maintains the balance of calcium and phosphorus in bony fish and as a paracrine/autocrine factor involved in many physiological/pathological processes in humans, including carcinogenesis. In this review, we provide an overview of (a) the possible mechanisms through which STC1 affects the malignant properties of cancer, (b) transcriptional and post-transcriptional regulation pathways of STC1 and (c) the potential clinical relevance of STC1 as a cancer biomarker and even a therapeutic target in the future. Exploring the role of STC1 in cancer development may provide a better understanding of the tumorigenesis process in humans and may facilitate finding an effective therapeutic method against cancer.

Stanniocalcin-1 (STC-1), a downstream effector molecule in latanoprost signaling, acts independent of the FP receptor for intraocular pressure reduction

Prostaglandin F2 alpha (PGF2α) analogues such as latanoprost are common first-line intraocular pressure (IOP) lowering medications. However, their clinical use is limited in some patient populations due to minimal or no IOP lowering response or side effects. In searching for a more targeted approach for IOP reduction, our lab recently identified Stanniocalcin-1 (STC-1) as a molecule that was required for latanoprost-mediated IOP reduction and also acted as a stand-alone IOP lowering agent. In order to determine whether latanoprost and STC-1 were equivalent and/or additive for IOP reduction, we treated C57BL/6J mice with one or a combination of these agents and measured IOP. Importance of the FP receptor for latanoprost- and STC-1-mediated IOP reduction was examined in C57BL/6J mice utilizing the pharmacologic FP receptor inhibitor AL-8810 as well as FP receptor knockout mice generated in our laboratory. Latanoprost-free acid (LFA) and STC-1 reduced IOP to a similar degree and were non-additive in C57BL/6J mice. As expected, the IOP lowering effects of LFA were abrogated by pharmacologic inhibition of the FP receptor with AL-8810 and in FP receptor knockout mice. In contrast, STC-1 maintained IOP-lowering effects in the presence of AL-8810 and also in FP receptor knockout mice. These results suggest that LFA and STC-1 show equivalent and non-additive IOP reduction in C57BL/6J mice and that unlike LFA, STC-1-mediated IOP reduction occurs independent of the FP receptor.

Stanniocalcin-1 is a Modifier of Oxygen-Induced Retinopathy Severity

Purpose/Aim: Abnormal activation of signaling pathways related to angiogenesis, inflammation, and oxidative stress has been implicated in the pathophysiology of retinopathy of prematurity (ROP), a leading cause of blindness in pre-term infants. Therapies for ROP include laser and anti-vascular endothelial growth factor agents. However, these therapies have side effects, and even with adequate treatment, visual acuity can be impaired. Novel therapeutic options are needed. Stanniocalcin-1 (STC-1) is a neuroprotective protein with anti-inflammatory and anti-oxidative stress properties. Rodent models of oxygen-induced retinopathy (OIR) were selected to determine whether STC-1 plays a role in the development of OIR.Materials and methods: STC-1 gene and protein expression was first evaluated in the Sprague Dawley rat OIR model that is most similar to human ROP. OIR was then induced in wild-type and Stc-1-/- mice. Retinas were isolated and evaluated for avascular and neovascular area on retinal flat mounts. Quantification of gene expression by quantitative real-time PCR was performed. VEGF was assayed by ELISA in media obtained from induced pluripotent stem-cell-derived retinal pigment epithelial (iPS-RPE) cells following treatment with recombinant STC-1.Results: STC-1 was significantly upregulated in a rat model of OIR compared to room air controls at the gene (P < .05) and protein (P < .001) level. Stc-1-/- OIR mice showed significantly worse ROP compared to wild-type mice as assessed by avascular (20.2 ± 2.4% vs 15.2 ± 2.5%; P = .02) and neovascular area (14.3 ± 2.7% vs 8.8 ± 3.7%; P < .05). Transcript levels of vascular endothelial growth factor-A were significantly higher in Stc-1-/- OIR mice compared to wild-type controls (P = .03). STC-1 reduced VEGF production in iPS-RPE cells (P = .01).Conclusions: STC-1 plays a role in the OIR stress response and development of pathologic vascular features in rodent OIR models by regulating VEGF levels.

Stanniocalcin-1 ameliorates cerebral ischemia by decrease oxidative stress and blood brain barrier permeability

Blood brain barrier (BBB) permeability and oxidative stress have been reported to be important mechanisms for brain damage following ischemic stroke and stanniocalcin-1 (STC-1), a neuroprotective protein, has anti-inflammatory and anti-oxidative stress properties. Herein, we report the effect of STC-1 on BBB permeability and brain oxidative stress after stroke in an animal model. Male Wistar received an intracerebroventricularly injection of human recombinant STC-1 (100 ng/kg) or saline and were subjected to sham procedure or global cerebral ischemia/reperfusion (I/R) model. Six and 24 h after I/R, neurological evaluation was performed; at 24 h brain water content was evaluated in the total brain, and BBB permeability, nitrite/nitrate (N/N) concentration, lipid peroxidation, protein carbonyls formation, superoxide dismutase (SOD) and catalase (CAT) activity were determined in the hippocampus, cortex, prefrontal cortex, striatum and cerebellum. Rats exhibited neurological deficit at 6 and 24 h after I/R and STC-1 reduction at 24 h. After I/R there were an increase of brain water content, BBB permeability in the hippocampus, cortex and pre-frontal cortex and N/N in the hippocampus, and STC-1 decreased this level only in the hippocampus. STC-1 decreased lipid peroxidation in the hippocampus, cortex and prefrontal cortex and protein oxidative damage in the hippocampus and cortex. SOD activity decreased in the hippocampus, cortex and prefrontal cortex after I/R and STC-1 reestablished these levels in the hippocampus and cortex. CAT activity decreased only in the hippocampus and cortex and STC-1 increased the CAT activity in the hippocampus. Our data provide the first experimental demonstration that STC-1 reduced brain dysfunction associated with cerebral I/R in rats, by decreasing BBB permeability and oxidative stress parameters.

Role of stanniocalcin-1 in breast cancer

Breast cancer is a highly heterogeneous disease consisting of five disease subtypes with distinct histological characteristics, clinical behaviors and prognostic features. Stanniocalcin-1 (STC1) is a secreted glycoprotein hormone that has been demonstrated to regulate calcium and phosphate homeostasis. Mammalian STC1 is expressed in various tissues and is implicated in multiple physiological and pathophysiological processes. In addition, growing evidence has suggested that STC1 serves an oncogenic role in a number of different types of tumor. However, the role of STC1 in breast cancer is complex, considering that some studies have shown that it exerts an oncogenic role, whereas other studies have demonstrated the opposite. The aim of the present review article is to evaluate the currently available data on mammalian STC1 and discuss its potential roles in each subtype of breast cancer.

Intravitreal Stanniocalcin-1 Enhances New Blood Vessel Growth in a Rat Model of Laser-Induced Choroidal Neovascularization

Purpose

The purpose of this study was to investigate the impact of stanniocalcin-1 (STC-1), a photoreceptor-protective glycoprotein, on the development of choroidal neovascularization (CNV) in relation to VEGF and its main receptor (VEGFR2) expression after laser injury.

Methods

In rats, CNV was induced by laser photocoagulation in both eyes, followed by intravitreal injection of STC-1 in the right eye and vehicle or denatured STC-1 injection in the left eye as control. Two weeks after laser injury, fundus autofluorescence (FAF) imaging and fundus fluorescein angiography (FFA) were performed. Fluorescein leakage from CNV was graded using a defined scale system. The size of CNV was quantified with spectral domain optical coherence tomography (SD-OCT), fluorescein-labeled choroid-sclera flat mounts, and hematoxylin-eosin staining. Protein expressions were evaluated by Western blot.

Results

Photocoagulation produced a well-circumscribed area of CNV. With STC-1 treatment, CNV lesions assessed by FAF were increased by 50% in both intensity and area. The CNV lesions were also increased with SD-OCT, flat-mount, and histologic analyses. FFA disclosed enhanced fluorescein leakage in CNV lesions in STC-1 treated eyes. The STC-1 protein was detected in the choroidal tissue and its level was increased with CNV lesions in correlation with VEGF and VEGFR2 expressions. Intravitreal administration of STC-1 significantly increased choroidal expression of both VEGF and VEGFR2 proteins.

Conclusions

Chorodial tissue expresses STC-1, which seemingly acts as a stress response protein by enhancing pathological new blood vessel growth in laser-induced CNV. It is likely that STC-1 promotes CNV development via VEGF signaling.

Long-term photoreceptor rescue in two rodent models of retinitis pigmentosa by adeno-associated virus delivery of Stanniocalcin-1

Retinal degenerations, including age-related macular degeneration and the retinitis pigmentosa family of diseases, are among the leading causes of legal blindness in the United States. We previously found that Stanniocalcin-1 (STC-1) reduced photoreceptor loss in the S334ter-3 and Royal College of Surgeons rat models of retinal degeneration. The results were attributed in part to a reduction in oxidative stress. Herein, we tested the hypothesis that long-term delivery of STC-1 would provide therapeutic rescue in more chronic models of retinal degeneration. To achieve sustained delivery, we produced an adeno-associated virus (AAV) construct to express STC-1 (AAV-STC-1) under the control of a retinal ganglion cell targeting promoter human synapsin 1 (hSYN1). AAV-STC-1 was injected intravitreally into the P23H-1 and S334ter-4 rhodopsin transgenic rats at postnatal day 10. Tissues were collected at postnatal day 120 for confirmation of STC-1 overexpression and histologic and molecular analysis. Electroretinography (ERG) was performed in a cohort of animals at that time. Overexpression of STC-1 resulted in a significant preservation of photoreceptors as assessed by outer nuclear thickness in the P23H-1 (P < 0.05) and the S334ter-4 (P < 0.005) models compared to controls. Additionally, retinal function was significantly improved in the P23H-1 model with overexpressed STC-1 as assessed by ERG analysis (scotopic b-wave P < 0.005 and photopic b-wave P < 0.05). Microarray analysis identified common downstream gene expression changes that occurred in both models. Genes of interest based on their function were selected for validation by quantitative real-time PCR and were significantly increased in the S334ter-4 model.

Stanniocalcin-1 Is an Ocular Hypotensive Agent and a Downstream Effector Molecule That Is Necessary for the Intraocular Pressure-Lowering Effects of Latanoprost

Purpose

To identify downstream signaling molecules through which intraocular pressure (IOP) is lowered following treatment with the prostaglandin analog latanoprost.

Methods

Total RNA and protein isolated from primary human Schlemm's canal cells (n = 3) treated with latanoprost (free acid; 100 nM) were processed for quantitative PCR and Western blot analysis. IOP was evaluated in stanniocalcin-1 (STC-1^−/−) and wild-type mice following treatment with latanoprost or Rho kinase inhibitor Y27632. Human anterior segment pairs (n = 8) were treated with recombinant STC-1 (5, 50, or 500 ng/mL) and pressure was recorded using custom-designed software. The effect of recombinant STC-1 (0.5 mg/mL) on IOP was evaluated in wild-type mice. Tissue morphology was evaluated by light and transmission electron microscopy.

Results

Increased STC-1 mRNA (4.0- to 25.2-fold) and protein expression (1.9- to 5.1-fold) was observed within 12 hours following latanoprost treatment. Latanoprost reduced IOP in wild-type mice (22.0% ± 1.9%), but had no effect on STC-1^−/− mice (0.5% ± 0.7%). In contrast, Y27632 reduced IOP in both wild-type (12.5% ± 1.2%) and in STC-1^−/− mice (13.1% ± 2.8%). Human anterior segments treated with STC-1 (500 ng/mL) showed an increase in outflow facility (0.15 ± 0.03 to 0.27 ± 0.09 μL/min/mm Hg) while no change was observed in paired vehicle-treated controls. Recombinant STC-1 reduced IOP in wild-type mice by 15.2% ± 3.0%. No observable morphologic changes were identified between treatment groups when evaluated by microscopy.

Conclusions

Latanoprost-induced reduction of IOP is mediated through the downstream signaling molecule STC-1. When used by itself, STC-1 exhibits ocular hypotensive properties.

Depletion of carbonic anhydrase IX abrogates hypoxia-induced overexpression of stanniocalcin-1 in triple negative breast cancer cells

Carbonic anhydrase IX (CAIX) is a pH-regulating enzyme that plays a key role in maintaining an alkaline intracellular pH under hypoxic conditions. It is overexpressed in a variety of solid cancers, including breast cancer (BC), and has been implicated in the migration, invasion and stemness of breast cancer cells. Therefore, CAIX recently emerged as a novel therapeutic target for the treatment of BC. To gain an insight into the mechanism of action of CAIX inhibitors, we investigated the impact of CAIX knock-down on the transcriptional response to hypoxia in 2 BC cell lines - MCF7 and MDA-MB-231, by performing a global gene expression analysis. This showed that CAIX knock-down had a relatively minor effect on the global transcriptional response to hypoxia, however it blocked hypoxia-induced upregulation of stanniocalcin-1 (STC1), a secreted glycoprotein that has been shown to promote tumor progression and metastasis in BC. Kaplan-Meier survival analysis showed that high STC1 expression is significantly associated with poor survival in patients with basal-type breast cancer but not luminal A and HER2+ subtypes. Moreover, the association was particularly high in a subgroup of basal-type BC patients with TP53 mutations thus revealing a putative cooperation of STC1 with mutated TP53 in generating highly aggressive BC subgroup. Taken together, these findings show that CAIX inhibitors at least partially act through blocking STC1 induction in BC cells and reveal a subgroup of BC patients, who potentially would benefit most from the treatment with CAIX inhibitors.

Evolution and functions of stanniocalcins in cancer

Stanniocalcin (STC), first isolated from the corpuscles of stannius of teleost fishes, was originally known for its regulation on calcium/phosphate transport. Increasing evidence demonstrates that STCs display the important function in some physiological and pathological behaviors such as calcium regulation, oxidative stress, anti-inflammation, angiogenesis, ischemia reperfusion, nerve diseases, etc. Moreover, STCs are implicated in the development and progression of multiple malignancies through promoting cell growth, proliferation, invasion, metastasis, and apoptotic escape. Some studies have shown that NF-κB upregulates STC expression, thereby activating the downstream HIF-1/ERK1/2 signaling pathway, enhancing the transcriptional activity of tumor-related factors (MMP-2/9, cyclinD1, Bcl-2, N-cadherin, etc) and contributing to tumorigenesis. Here, this brief review describes recent progress of STCs in mammalians, focused mainly on their critical functions in cancer.

Stanniocalcin-1 Protects a Mouse Model from Renal Ischemia-Reperfusion Injury by Affecting ROS-Mediated Multiple Signaling Pathways

Stanniocalcin-1 (STC-1) protects against renal ischemia-reperfusion injury (RIRI). However, the molecular mechanisms remain widely unknown. STC-1 inhibits reactive oxygen species (ROS), whereas most ROS-mediated pathways are associated with ischemic injury. Therefore, to explore the mechanism, the effects of STC-1 on ROS-medicated pathways were studied. Non-traumatic vascular clamps were used to establish RIRI mouse models. The serum levels of STC-1, interleukin-6 (IL-6), interferon (IFN) γ, P53, and capase-3 were measured by ELISA kits. Superoxide dismutase (SOD) and malondialdehyde (MDA) were measured by fluorescence spectrofluorometer. All these molecules changed significantly in a RIRI model mouse when compared with those in a sham control. Kidney cells were isolated from sham and model mice. STC-1 was overexpressed or knockout in these kidney cells. The molecules in ROS-medicated pathways were measured by real-time quantitative PCR and Western blot. The results showed that STC-1 is an effective ROS scavenger. The serum levels of STC-1, MDA and SOD activity were increased while the serum levels of IL-6, iIFN-γ, P53, and capase-3 were decreased in a model group when compared with a sham control (p < 0.05). Furthermore, the levels of STC-1,p53, phosphorylated mitogen-activated protein kinase kinase (p-MEKK-1), c-Jun N-terminal kinase (p-JNK), extracellular signal-regulated kinase (p-ERK), IkB kinase (p-IKK), nuclear factor (NF) κB, apoptosis signal-regulating kinase 1 (ASK-1) and caspase-3 changed significantly in kidney cells isolated from a RIRI model when compared to those isolated from a sham control (p < 0.05). Meanwhile, STC-1 overexpression or silence caused significant changes of the levels of these ROS-mediated molecules. Therefore, STC-1 maybe improve anti-inflammation, anti-oxidant and anti-apoptosis activities by affecting ROS-mediated pathways, especially the phospho-modifications of the respective proteins, resulting in the increase of SOD and reduce of capase-3, p53, IL-6 and IFN-γ.

Characteristics of a rat model of an open craniocerebral injury at simulated high altitude

To establish a rat model of an open craniocerebral injury at simulated high altitude and to examine the characteristics of this model. Rats were divided randomly into a normobaric group and a high-altitude group and their corresponding control groups. A rat model of an open craniocerebral injury was established with a nail gun shot. Simulated high-altitude conditions were established with a hypobaric chamber at 0.6 ATA to mimic pressure at an altitude of 4000 m. Mortality, brain water content (BWC), Evans blue content, pathology, regional cerebral blood flow (rCBF), partial pressure of brain tissue oxygen (PbtO₂), and brainstem auditory-evoked potential were observed after injury. The mortality of the high-altitude group was significantly greater than that of the normobaric group within 72 h after injury (P<0.05). BWC and Evans blue content increased by 48 h after injury (P<0.05); pathological changes in damaged brains were more serious. In contrast, rCBF and PbtO₂ had decreased markedly by 72 h (P<0.01); brainstem auditory-evoked potential values were significantly prolonged (P<0.05). Moreover, an inverse correlation between rCBF and BWC and a positive correlation between rCBF and PbtO₂ were found. The rat model of an open craniocerebral injury at simulated high altitude can be established successfully using a nail gun shot and a hypobaric chamber. The injury characteristics at high altitude were more serious, rapid, and prolonged than those in the normobaric group.

STC1 expression is associated with tumor growth and metastasis in breast cancer

Stanniocalcin-1 (STC1) is a secreted glycoprotein implicated in several pathologies including retinal degeneration, cerebral ischemia, angiogenesis and inflammation. Aberrant STC1 expression has been reported in breast cancer but the significance of this is not clear. High levels of STC1 expression were found in the aggressive 4T1 murine mammary tumor cells and in the MDA-MB-231 human breast cancer line. To investigate its significance, stable clones with STC1 down-regulation using shRNA were generated in both tumor models. The consequences of STC1 down-regulation on cell proliferation, chemotactic invasion, tumor growth and metastasis were assessed. Down-regulation of STC1 in the 4T1 murine mammary tumor cells had a major impact on mammary tumor growth. This observation was replicated in a second tumor model with the MDA-MB-231 human breast cancer line, with a significant reduction in primary tumor formation and a major inhibition of metastasis as well. Interestingly, in both models, proliferation in vitro was not affected. Subsequent microarray gene expression profiling identified 30 genes to be significantly altered by STC1 down-regulation, the majority of which are associated with known hallmarks of carcinogenesis. Furthermore, bioinformatic analysis of breast cancer datasets revealed that high expression of STC1 is associated with poor survival. This is the first study to show definitively that STC1 plays an oncogenic role in breast cancer, and indicates that STC1 could be a potential therapeutic target for treatment of breast cancer patients.