Predicting chemoresponsiveness in epithelial ovarian cancer patients using circulating small extracellular vesicle-derived plasma gelsolin.

BACKGROUND: Resistance to chemotherapy continues to be a challenge when treating epithelial ovarian cancer (EOC), contributing to low patient survival rates. While CA125, the conventional EOC biomarker, has been useful in monitoring patients' response to therapy, there are no biomarkers used to predict treatment response prior to chemotherapy. Previous work in vitro showed that plasma gelsolin (pGSN) is highly expressed in chemoresistant EOC cell lines, where it is secreted in small extracellular vesicles (sEVs). Whether sEVs from tumour cells are secreted into the circulation of EOC patients and could be used to predict patient chemoresponsiveness is yet to be determined. This study aims to identify if sEV-pGSN in the circulation could be a predictive biomarker for chemoresistance in EOC. METHODS: Sandwich ELISA was used to measure pGSN concentrations from plasma samples of 96 EOC patients (primarily high grade serous EOC). sEVs were isolated using ExoQuick ULTRA and characterized using western blot, nanoparticle tracking analysis, and electron microscopy after which pGSN was measured from the sEVs. Patients were stratified as platinum sensitive or resistant groups based on first progression free interval (PFI) of 6 or 12 months. RESULTS: Total circulating pGSN was significantly decreased and sEV-pGSN increased in patients with a PFI ≤ 12 months (chemoresistant) compared to those with a PFI > 12 months (chemosensitive). The ratio of total pGSN to sEV-pGSN further differentiated these groups and was a strong predictive marker for chemoresistance (sensitivity: 73.91%, specificity: 72.46%). Predetermined CA125 was not different between chemosensitive and chemoresistant groups and was not predictive of chemoresponsiveness prior to treatment. When CA125 was combined with the ratio of total pGSN/sEV-pGSN, it was a significant predictor of chemoresponsiveness, but the test performance was not as robust as the total pGSN/sEV-pGSN alone. CONCLUSIONS: Total pGSN/sEV-pGSN was the best predictor of chemoresponsiveness prior to treatment, outperforming the individual biomarkers (CA125, total pGSN, and sEV-pGSN). This multianalyte predictor of chemoresponsiveness could help to inform physicians' treatment and follow up plan at the time of EOC diagnosis, thus improving patients' outcomes.

Delayed administration of recombinant plasma gelsolin improves survival in a murine model of severe influenza.

Background: Host-derived inflammatory responses contribute to the morbidity and mortality of severe influenza, suggesting that immunomodulatory therapy may improve outcomes. The normally circulating protein, human plasma gelsolin, is available in recombinant form (rhu-pGSN) and has beneficial effects in a variety of pre-clinical models of inflammation and injury.   Methods: We evaluated delayed therapy with subcutaneous rhu-pGSN initiated 3 to 6 days after intra-nasal viral challenge in a mouse model of influenza A/PR/8/34. Results: Rhu-pGSN administered starting on day 3 or day 6 increased survival (12-day survival: 62 % vs 39 %, pGSN vs vehicle; p < 0.00001, summary of 18 trials), reduced morbidity, and decreased pro-inflammatory gene expression. Conclusions: Rhu-pGSN improves outcomes in a highly lethal influenza model when given after a clinically relevant delay.

The effects of plasma gelsolin on human erythroblast maturation for erythrocyte production.

Gelsolin is an actin binding protein present in blood plasma and in cytoplasm of cells including macrophages. Gelsolin has important functions in cell cycle regulation, apoptotic regulation, and morphogenesis. Even though bone marrow macrophages and serum factors are critical for regulating erythropoiesis, the role of gelsolin on human erythroblasts has not been studied. Here, we investigated the effects of human recombinant plasma gelsolin (pGSN) on human immature erythroblasts. CD34+ cells isolated from cord blood were differentiated into erythroid cells in serum-free medium. When pGSN was applied to the culture medium, it accelerated basophilic and polychromatic erythroblast maturation and increased the enucleation rate with highly expressed erythropoiesis-related mRNAs. Also, pGSN was effective in reducing dysplastic changes caused by vincristine, suggesting its role in cell cycle progression at G2/M checkpoints. Also, pGSN activated caspase-3 during maturation stages in which caspase-3 functions as a non-apoptotic maturational signal or a pro-apoptotic signal depending on maturation stages. Our results suggest that pGSN has a pivotal role in maturation of erythroblasts and this factor might be one of the way how bone marrow macrophages and previously unknown serum factors work to control erythropoiesis. pGSN might be used as additive for in vitro production of erythrocytes.

Hepatoprotective effects of capping protein gelsolin against hyperoxia-induced hepatotoxicity, oxidative stress and DNA damage in neonatal rats.

Tissues and organs get exposed to high oxygen (O2) supply in hyperoxia conditions. The goal of this research was to investigate the protective effect of actin binding protein gelsolin on hyperoxia-induced hepatotoxicity through histopathology and measurement of oxidative stress parameters and DNA damage in a neonatal Wistar albino rats. The pups were randomly separated to four equal groups such as: normoxia control group (NC), normoxia plus gelsolin group (NG, 10 ng/kg bw/day gelsolin), hyperoxia (≥85% O2) group (HC), hyperoxia plus gelsolin group (HG, ≥85% O2; 10 ng/kg bw/day gelsolin). Histopathological changes of pups in hyperoxia condition were revealed in the form of severe leukocyte infiltration, vascular congestion, necrosis, vacuolar degeneration, binucleated hepatocytes and hemorrhage in the liver tissue. SOD, CAT, GPx and GST activities decreased and MDA level increased in the hyperoxia-induced group in liver tissue (P < 0.05). Tail DNA%, tail length and moment indicating DNA damage statistically increased in hyperoxia treatment groups when compared to controls. Treatment of rats with hyperoxia plus gelsolin prevented hyperoxia-induced changes in tissue structure, antioxidant enzyme activities and MDA level, mean tail DNA% and length. Based on these findings, gelsolin restored these changing to near normal levels but it does not protect completely in the hyperoxia conditions.

Gelsolin decreases actin toxicity and inflammation in murine multiple sclerosis.

Gelsolin is the fourth most abundant protein in the body and its depletion in the blood has been found in multiple sclerosis (MS) patients. How gelsolin affects the MS brain has not been studied. We found that while the secreted form of gelsolin (pGSN) decreased in the blood of experimental autoimmune encephalomyelitis (EAE) mice, pGSN concentration increased in the EAE brain. Recombinant human pGSN (rhp-GSN) decreased extracellular actin and myeloperoxidase activity in the brain, resulting in reduced disease activity and less severe clinical disease, suggesting that gelsolin could be a potential therapeutic target for MS.

Potential therapeutic implications of gelsolin in Alzheimer's disease.

The presence of amyloid plaques and vascular amyloid deposits is one of the pathological features of Alzheimer's disease (AD). Amyloid plaques and vascular deposits mainly consist of amyloid-ß (Aß), which is a metabolic product of amyloid-ß protein precursor cleaved by ß- and γ-secretase. Soluble Aß monomers readily aggregate into oligomers preceding the formation of insoluble fibrils, and Aß oligomers are more toxic than fibrils. Intensive therapeutic efforts have been attempted in the treatment of AD targeting Aß, including preventing Aß generation, inhibiting Aß aggregation, and promoting Aß clearance. The results show that amyloid plaque burden is reduced together with improved cognition performance in AD. Gelsolin, a multifunctional actin-binding protein, exists intracellularly as a cytoplasmic form and extracellularly as a secreted form in blood/cerebrospinal fluid. Gelsolin is suggested to be implicated in AD, based on the findings that some changes of gelsolin are correlated with disease progression rate in AD patients. Gelsolin binds Aß, inhibits its aggregation into fibrils, and protects cells from apoptosis induced by Aß. More importantly, administration or overexpression of gelsolin results in significant reduction of amyloid load and decrease of Aß level in AD transgenic mice. In this article, we review the most recent progress of gelsolin as a potential therapeutic strategy for treatment of AD, and discuss the possible mechanism involved in the clearance of amyloid plaques in AD.

Gelsolin: role of a functional protein in mitigating radiation injury.

The present study was conducted to explore the protective effect of exogenous gelsolin (GSN) in mice exposed to high-dose of radiation. Changes in the levels of GSNs in peripheral blood of mice and cytoplasm of cultured human intestinal epithelial cells (HIECs) were analyzed after their exposure to different doses of (137)Cs γ-rays at a fixed dose rate. The coagulation associated indices, such as prothrombin time (PT) and activated partial thromboplastin time (APTT) were measured. Effect on radiation-mediated oxidative damage was evaluated by estimating the altered glutathione (GSH) and malondialdehyde (MDA) concentrations in the blood. The results showed that radiation induced a pronounced decrease in the pGSN blood levels. However, the cGSN levels of irradiated HIECs were increased in a dose-dependent manner. Administration of recombinant human pGSN to irradiated mice resulted in an ameliorated clotting time as indicated by the PT and the APTT indices. The treatment of mice with hpGSN enhanced the blood levels of GSH while MDA concentrations were decreased indicating an improved antioxidant status. These results suggest that GSNs might play a regulatory role in the suppression of the tissue damage induced by acute radiation exposure.

Treatment with gelsolin reduces brain inflammation and apoptotic signaling in mice following thermal injury.

BACKGROUND: Burn survivors develop long-term cognitive impairment with increased inflammation and apoptosis in the brain. Gelsolin, an actin-binding protein with capping and severing activities, plays a crucial role in the septic response. We investigated if gelsolin infusion could attenuate neural damage in burned mice. METHODS: Mice with 15% total body surface area burns were injected intravenously with bovine serum albumin as placebo (2 mg/kg), or with low (2 mg/kg) or high doses (20 mg/kg) of gelsolin. Samples were harvested at 8, 24, 48 and 72 hours postburn. The immune function of splenic T cells was analyzed. Cerebral pathology was examined by hematoxylin/eosin staining, while activated glial cells and infiltrating leukocytes were detected by immunohistochemistry. Cerebral cytokine mRNAs were further assessed by quantitative real-time PCR, while apoptosis was evaluated by caspase-3. Neural damage was determined using enzyme-linked immunosorbent assay of neuron-specific enolase (NSE) and soluble protein-100 (S-100). Finally, cerebral phospho-ERK expression was measured by western blot. RESULTS: Gelsolin significantly improved the outcomes of mice following major burns in a dose-dependent manner. The survival rate was improved by high dose gelsolin treatment compared with the placebo group (56.67% vs. 30%). Although there was no significant improvement in outcome in mice receiving low dose gelsolin (30%), survival time was prolonged against the placebo control (43.1 ± 4.5 h vs. 35.5 ± 5.0 h; P < 0.05). Burn-induced T cell suppression was greatly alleviated by high dose gelsolin treatment. Concurrently, cerebral abnormalities were greatly ameliorated as shown by reduced NSE and S-100 content of brain, decreased cytokine mRNA expressions, suppressed microglial activation, and enhanced infiltration of CD11b+ and CD45+ cells into the brain. Furthermore, the elevated caspase-3 activity seen following burn injury was remarkably reduced by high dose gelsolin treatment along with down-regulation of phospho-ERK expression. CONCLUSION: Exogenous gelsolin infusion improves survival of mice following major burn injury by partially attenuating inflammation and apoptosis in brain, and by enhancing peripheral T lymphocyte function as well. These data suggest a novel and effective strategy to combat excessive neuroinflammation and to preserve cognition in the setting of major burns.

Plasma gelsolin is a marker and therapeutic agent in animal sepsis.

OBJECTIVE: Plasma gelsolin is a circulating actin-binding protein that serves a protective role against tissue injuries. Depletion of plasma gelsolin in systemic inflammation may contribute to adverse outcomes. We examined the role of plasma gelsolin in animal models of sepsis. DESIGN: Animal and laboratory experiments. SETTING: Academic research laboratory. SUBJECTS: Adult male mice. INTERVENTIONS: Mice subjected to endotoxin or cecal ligation and puncture (CLP) were treated with exogenous plasma gelsolin or placebo. MEASUREMENTS AND MAIN RESULTS: We document the depletion of plasma gelsolin (25-50% of normal) in murine models of sepsis associated with the presence of circulating actin within 6 hrs of septic challenge. Repletion of plasma gelsolin leads to solubilization of circulating actin aggregates and significantly reduces mortality in endotoxemic mice (survival rates were 88% in the gelsolin group vs. 0% in the saline group, p < .001) and in CLP-challenged mice (survival rates were 30% in the gelsolin group vs. 0% in the saline group, p = .001). Plasma gelsolin repletion also shifted the cytokine profile of endotoxemic mice toward anti-inflammatory (plasma interleukin-10 levels were 205 +/- 108 pg/mL in the gelsolin group vs. 39 +/- 29 pg/mL in the saline group, p = .02). CONCLUSIONS: We propose that circulation of particulate actin is a marker for sepsis-induced cell injury, that plasma gelsolin has a crucial protective role in sepsis, and that gelsolin replacement represents a potential therapy for this common lethal condition.

[Tumor suppressive function of gelsolin].

We examined the expression of gelsolin in a murine ras tumor and a number of human stomach, colon, bladder, and lung cancer cell lines and tissues. In most of the cell lines and tumor tissues, gelsolin expression was undetectable or extremely low in comparison with its expression in normal epithelial cells. Upon the introduction of the exogenous human wild-type gelsolin cDNA into human cancer cell lines, the gelsolin transfectants had greatly reduced colony-forming ability and tumorigenicity in vivo. After UVC irradiation, the gelsolin-overexpressing bladder cancer cells demonstrated increased accumulation and/or protracted delay in G2 phase as compared to neotransfected cells. UVC-induced production of diacylglycerol was reduced in gelsolin-overexpressed UMUC-2 cells as compared to neo-transfected UMUC-2 cells. Levels of cyclin B in the synchronized and gelsolin-overexpressing UMUC-2 cells remained low during the G2 delay. To investigate the in vivo efficacy of gene therapy with the gelsolin tumor suppressor, we treated human urinary bladder cancers (UMUC-2 and DAB-1), inoculated in nude mice, with recombinant retrovirus packaging cells containing the human gelsolin cDNA. This gene therapy resulted in remarkable tumor growth inhibition, and prolonged survival time in the majority of animals. These observations suggest that gelsolin plays a key role as a tumor suppressor by regulating a G2 checkpoint function of cancer cells through phosphoinositol lipid metabolism, and demonstrate the potential of using the gelsolin tumor suppressor in human urinary bladder carcinoma.