[Show abstract][Hide abstract] ABSTRACT: Aging is influenced by endocrine pathways including the growth hormone/insulin-like growth factor-1 (GH/IGF) axis. Mitochondrial function has also been linked to the aging process, but the relevant mitochondrial signals mediating the effects of mitochondria are poorly understood. Humanin is a novel signaling peptide that acts as a potent regulator of cellular stress responses and protects from a variety of in vitro and in vivo toxic and metabolic insults. The circulating levels of humanin decline with age in mice and humans. Here, we demonstrate a negative correlation between the activity of the GH-IGF axis and the levels of humanin, as well as a positive correlation between humanin and lifespan in mouse models with altered GH/IGF-I axis. Long-lived, GH-deficient Ames mice displayed elevated humanin levels, while short-lived GH-transgenic mice have reduced humanin levels. Furthermore, treatment with GH or IGF-I reduced circulating humanin levels in both mice and human subjects. Our results indicate that GH and IGF are potent regulators of humanin levels and that humanin levels correlate with lifespan in mice. This suggests that humanin represents a circulating mitochondrial signal that participates in modulating the aging process, adding a coordinated mitochondrial element to the endocrine regulation of aging.
[Show abstract][Hide abstract] ABSTRACT: Attenuated growth hormone and insulin-like growth factor-1 (GH/IGF-1) signaling is associated with extended lifespan in several animal models. However, the effect of diminished GH/IGF-1 activity on survival in humans has not been confirmed. We tested the hypothesis that IGF-1 levels in nonagenarians (n = 184), measured at study enrollment, predict the duration of their incremental survival. In the Kaplan-Meier analysis, females with IGF-1 levels below the median (≤ 96 ng mL(-1) ) had significantly longer survival compared with females with levels above the median, P < 0.01. However, this survival advantage was not observed in males (P = 0.83). On the other hand, in both males and females with a history of cancer, lower IGF-1 levels predicted longer survival (P < 0.01). IGF-1 level remained a significant predictor of survival duration in linear regression models after multivariable adjustment in females (P = 0.01) and individuals with a history of cancer (P < 0.01). We show for the first time that low IGF-1 levels predict life expectancy in exceptionally long-lived individuals.
[Show abstract][Hide abstract] ABSTRACT: Mice and humans with growth hormone receptor/IGF-1 deficiencies display major reductions in age-related diseases. Because protein restriction reduces GHR-IGF-1 activity, we examined links between protein intake and mortality. Respondents aged 50-65 reporting high protein intake had a 75% increase in overall mortality and a 4-fold increase in cancer death risk during the following 18 years. These associations were either abolished or attenuated if the proteins were plant derived. Conversely, high protein intake was associated with reduced cancer and overall mortality in respondents over 65, but a 5-fold increase in diabetes mortality across all ages. Mouse studies confirmed the effect of high protein intake and GHR-IGF-1 signaling on the incidence and progression of breast and melanoma tumors, but also the detrimental effects of a low protein diet in the very old. These results suggest that low protein intake during middle age followed by moderate to high protein consumption in old adults may optimize healthspan and longevity.
[Show abstract][Hide abstract] ABSTRACT: Ganitumab is a fully human monoclonal antibody to the human type I insulin-like growth factor receptor (IGF1R). Binding assays showed that ganitumab recognized murine (m)IGF1R with sub-nanomolar affinity (KD=0.22nM) and inhibited the interaction of murine IGF1R with IGF-1 and IGF-2. Ganitumab inhibited IGF-1-induced activation of IGF1R in murine lungs and CT-26 murine colon carcinoma cells and tumors. Adding ganitumab to 5-fluorouracil resulted in enhanced inhibition of tumor growth in the CT-26 model. Pharmacological intervention with ganitumab in naïve nude mice resulted in a number of physiological changes previously described in animals with targeted deletions of IGF-1 and IGF1R, including inhibition of weight gain, reduced glucose tolerance, and significant increase in serum levels of mGH, mIGF-1, and mIGFBP-3. FACS analysis identified GR1/CD11b-positive cells as the highest IGF1R-expressing cells in murine peripheral blood. Administration of ganitumab led to a dose-dependent, reversible decrease in the number of peripheral neutrophils with no effect on erythrocytes or platelets. These findings indicate that acute IGF-availability for its receptor plays a critical role in physiological growth, glucose metabolism, and neutrophil physiology and support the presence of a pituitary IGF1R-driven negative-feedback loop that tightly regulates serum IGF-1 levels through growth hormone signaling.
Journal of Endocrinology 02/2014; · 4.06 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Titrating the dosage of growth hormone (GH) to serum levels of insulin-like growth factor-I (IGF-I) is a feasible treatment strategy in children with GH deficiency (GHD) and idiopathic short stature (ISS). The objective was to assess the dose-sparing effect and theoretical safety of IGF-I based GH therapy.
This was a post-hoc analysis of previously described 2-year, multicenter, open-label, randomised, outpatient, controlled clinical trial in 172 prepubertal short children (age 7.5±2.4 years; height standard deviation score [HSDS] -2.64±0.61) classified by baseline peak GH levels as GHD (<7 ng/mL) or ISS (≥7 ng/mL).
Conventional weight-based dosing of GH (0.04 mg/kg/day) (n=34) or GH dosing titrated to an IGF-I target of 0 SDS (IGF0T; n=70) or IGF-I target of +2 SDS (IGF2T; n=68).
Change in HSDS per GH mg/kg/day dose (∆HSDS/GH-dose ratio) and proportion of IGF-I levels above +2 SDS at end of 2 years.
GH dosing titrated to an IGF-I target of 0 SDS was the most dose-sparing treatment regimen for GHD or ISS children (mean±SE ∆HSDS/GH-dose ratios 48.1±4.4 and 32.5±2.8, respectively) compared with conventional dosing (30.3±6.6 and 21.3±3.5, respectively; P=0.02, P=0.005) and IGF2T (32.7±4.8 and 16.3±2.8, respectively; P=0.02, P<0.0001). IGF0T also resulted in fewest IGF-I excursions above +2 SDS (6.8% vs 30.0% for conventional dosing; P<0.01).
IGF-I-based GH dosing, targeted to age- and gender-adjusted means, may offer a more dose sparing and potentially safer mode of therapy than traditional weight-based dosing. This article is protected by copyright. All rights reserved.
[Show abstract][Hide abstract] ABSTRACT: We previously reported that a 4-6 week low-fat fish oil (LFFO) diet did not affect serum IGF-1 levels (primary outcome) but resulted in lower omega-6 to omega-3 fatty acid ratios in prostate tissue and lower prostate cancer proliferation (Ki67) as compared to a Western diet (WD). In this post-hoc analysis, the effect of the LFFO intervention on serum pro-inflammatory eicosanoids, LTB4 and 15(S)-HETE, and the cell cycle progression (CCP) score were investigated. Serum fatty acids and eicosanoids were measured by gas chromatography and ELISA. CCP score was determined by RT-PCR. Associations between serum eicosanoids, Ki67, and CCP score were evaluated using partial correlation analyses. BLT1 (LTB4 receptor) expression was determined in prostate cancer cell lines and prostatectomy specimens. Serum omega-6 fatty acids and 15(S)-HETE levels were significantly reduced, and serum omega-3 levels were increased in the LFFO group relative to the WD group, whereas there was no change in LTB4 levels. The CCP score was significantly lower in the LFFO compared to the WD group. The 15(S)-HETE change correlated with tissue Ki67 (R=0.48; p<0.01) but not with CCP score. The LTB4 change correlated with the CCP score (r=0.4; p=0.02) but not with Ki67. The LTB4 receptor BLT1 was detected in prostate cancer cell lines and human prostate cancer specimens. In conclusion, a LFFO diet resulted in decreased 15(S)-HETE levels and lower CCP score relative to a WD. Further studies are warranted to determine whether the LFFO diet anti-proliferative effects are mediated through the LTB4/BLT1 and 15(S)-HETE pathways.
Cancer Prevention Research 10/2013; · 4.89 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Humanin (HN) is a novel 24-amino acid mitochondrial-derived peptide that has demonstrated diverse cytoprotective effects, including an emerging role in diabetes. The purpose of this study was to examine the pharmacokinetics of humanin analogues, which show great potential as therapeutic agents (HNG and the nonIGFBP-3 binding, HNGF6A). 11-week-old male IGFBP-3(-/-) and wild type (WT) mice were divided into three groups: WT mice treated with HNG, WT mice treated with HNGF6A, and IGFBP-3(-/-)mice treated with HNG. Plasma was obtained from mice following intraperitonial (IP) injection with HN analogues, and HN levels were measured with ELISA. WT mice treated with HNGF6A and IGFBP-3(-/-)mice treated with HNG displayed a longer half-life of HN compared with WT mice treated with HNG. Following HNG injection, both IGF-1 and IGFBP-3 levels decreased over time. Adult male Sprague Dawley rats were also IP injected with HNG, and HN levels were measured in various tissues (plasma, liver, heart, and brain) by ELISA. The half-life of HN was found to be longer in rats compared with mice. In rats, HN levels were found to be highest in plasma, present in liver, and undetectable in brain or heart. The current study provides evidence of HN and IGFBP-3 association in the circulation, and suggests that native HN may modulate the distribution of IGF-1 and IGFBP-3. The results also demonstrate varying kinetic profiles of HN analogues and interspecies variation in rodents. Sustainable levels of circulating HN measured in plasma underline the potential value of HN analogues as a new therapeutic intervention in the treatment of diabetes.
[Show abstract][Hide abstract] ABSTRACT: Background/Aims: Limited data exist on long-term dose response to recombinant human growth hormone (rhGH) in prepubertal GH-deficient (GHD) children. The effect of low, intermediate, and high-dose rhGH (25, 50, and 100 μg/kg/day, respectively) on growth and puberty in children with GHD was investigated for 48 months. Methods: A prospective, dose-response study in 111 patients (aged 3-16 years) evaluated growth velocity (cm/year), height standard deviation score (HSDS), corrected HSDS, bone age/chronologic age ratio, body mass index SDS, and the percentage starting puberty. Results: Dose-related increases were observed in growth velocity (p < 0.001), HSDS (p < 0.001), and corrected HSDS (p < 0.001) from baseline to 48 months. Increases in the bone age/chronologic age ratio (p = 0.043) and body mass index SDS (p = 0.018) occurred up to 36 months at intermediate and high doses versus low-dose rhGH; increases at 48 months were not significant. No significant differences in growth were found between intermediate and high doses of rhGH. Percentages of rhGH-treated patients starting puberty at each dose were equivalent (p = 0.607). Conclusions: rhGH, 50 and 100 μg/kg/day, induced greater growth than 25 μg/kg/day without altering the proportion of children starting puberty. The maximum approved dose for pubertal patients (100 μg/kg/day) is not required or recommended for prepubertal children with GHD.
Hormone Research in Paediatrics 06/2013; · 1.55 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Context:Prostate cancer patients at increased risk for relapse after prostatectomy were treated in a neo-adjuvant study with androgen deprivation therapy (ADT) in combination with cixutumumab, an inhibitory fully human monoclonal antibody against insulin-like growth factor receptor 1 (IGF-IR).Objective:A clinical trial with prospective collection of serum and tissue was designed to test the potential clinical efficacy of neoadjuvant IGF-IR blockade combined with ADT in these patients. Effect of body mass index (BMI) on response of IGF-IR/insulin components to IGF-IR blockade was also examined.Design:Eligibility for the trial required the presence of high-risk prostate adenocarcinoma. Treatment consisted of bicalutamide, goserelin, and cixutumumab for thirteen weeks before prostatectomy. Here we report on an analysis of serum samples from 29 enrolled patients. Changes in IGF and glucose homeostasis pathways were compared to control samples from patients in a concurrent clinical trial of neoadjuvant ADT alone.Results:Significant increases were seen in growth hormone (p = 0.001), IGF-I (p < 0.0001), IGF-II (p = 0.003), IGFBP-3 (p < 0.0001), C-peptide (p = 0.0038), and insulin (p = 0.05) compared to patients treated with ADT alone. IGFBP-1 levels were significantly lower in the cixutumumab+ADT cohort (p = 0.001). No significant changes in blood glucose were evident. Patients with BMIs in the normal range had significantly higher growth hormone (p < 0.05) and IGFBP-1 (p < 0.05) levels compared to overweight and obese patients.Conclusions:Patients with IGF-IR blockade in combination with ADT demonstrated significant changes in IGF and glucose homeostasis pathway factors compared to patients receiving ADT alone. In the patients receiving combination therapy, patients with normal BMI had serum levels of glucose homeostasis components similar to individuals in the ADT alone cohort, while patients with overweight and obese BMIs had serum levels that differed from the ADT cohort.
The Journal of Clinical Endocrinology and Metabolism 03/2013; · 6.31 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Mitochondria have been largely considered as 'end-function' organelles, servicing the cell by producing energy and regulating cell death in response to complex signals. Being cellular entities with vital roles, mitochondria communicate back to the cell and actively engage in determining major cellular policies. These signals, collectively referred to as retrograde signals, are encoded in the nuclear genome or are secondary products of mitochondrial metabolism. Here, we discuss humanin, the first small peptide of a putative set of mitochondrial-derived peptides (MDPs), which exhibits strong cytoprotective actions against various stress and disease models. The study of humanin and other mitochondrial-derived retrograde signal peptides will aid in the identification of genes and peptides with therapeutic and diagnostic potential in treating human diseases.
Trends in Endocrinology and Metabolism 02/2013; · 8.90 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Calorie restriction (CR) inhibits prostate cancer progression, partially through modulation of the IGF axis. IGF-1 receptor (IGF-1R) blockade reduces prostate cancer xenograft growth. We hypothesized that combining calorie restriction with IGF-1R blockade would have an additive effect on prostate cancer growth. Severe combined immunodeficient mice were subcutaneously injected with 22Rv1 cells and randomized to: (1) Ad libitum feeding/intraperitoneal saline (Ad-lib); (2) Ad-lib/20 mg/kg twice weekly, intraperitoneal ganitumab [anti-IGF-1R antibody (Ad-lib/Ab)]; (3) 40% calorie restriction/intraperitoneal saline (CR); (4) CR/ intraperitoneal ganitumab, (CR/Ab). CR and ganitumab treatment were initiated one week after tumor injection. Euthanasia occurred 19 days post treatment. Results showed that CR alone decreased final tumor weight, plasma insulin and IGF-1 levels, and increased apoptosis. Ganitumab therapy alone reduced tumor growth but had no effect on final tumor weight. The combination therapy (CR/Ab) further decreased final tumor weight and proliferation, increased apoptosis in comparison to the Ad-lib group, and lowered plasma insulin levels relative to the Ad-lib and Ad-lib/Ab groups. Tumor AKT activation directly correlated with plasma IGF-1 levels. In conclusion, whereas ganitumab therapy modestly affected 22Rv1 tumor growth, combining IGF-1R blockade with calorie restriction resulted in a significant decrease in final tumor weight and improved metabolic profile.
International Journal of Molecular Sciences 01/2013; 14(7):13782-95. · 2.46 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: The discovery of humanin, a novel, mitochondria-derived peptide, has created a potentially new category of biologically active peptide. As more research unravels the endogenous role of humanin as well as its potential pharmacological use, its role in stress resistance has become clearer. Humanin protects cells from oxidative stress, serum starvation, hypoxia, and other insults in vitro and also improves cardiovascular disease as well as Alzheimer's disease in vivo. In this review we discuss the emerging role of humanin in stress resistance and its proposed mechanism of action.
Journal of Molecular Endocrinology 12/2012; · 3.58 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Humanin is a small endogenous anti-apoptotic peptide, originally identified as protective against Alzheimer's disease but subsequently also found on human endothelium as well as carotid artery plaques. Endothelial dysfunction is a precursor to the development of atherosclerotic plaques, which are characterized by a highly pro-inflammatory, reactive oxygen species, and apoptotic milieu. Previous animal studies demonstrated that humanin administration may improve endothelial function. Thus, the aim of this study was to test the hypothesis that patients with coronary endothelial dysfunction have reduced systemic levels of humanin. Forty patients undergoing coronary angiography and endothelial function testing were included and subsequently divided into two groups based on coronary blood flow (CBF) response to intracoronary acetylcholine (normal > 50% increase from baseline, n=20 each). Aortic plasma samples were obtained at the time of catheterization for the analysis of humanin levels and traditional biomarkers of atherosclerosis including C-reactive protein, Lp-Pla2, and homocysteine. Baseline characteristics were similar in both groups. Patients with coronary endothelial dysfunction (change in CBF = -33±25%) had significantly lower humanin levels (1.3±1.1 ng/ml vs. 2.2±1.5 ng/ml, p=0.03) compared to those with normal coronary endothelial function (change in CBF = 194±157%). There was a significant and positive correlation between improved CBF and humanin levels (p=0.0091) not seen with changes in coronary flow reserve (p=0.76). C-reactive protein, Lp-Pla(2), and homocysteine were not associated with humanin levels. We observed that preserved human coronary endothelial function is uniquely associated with higher systemic humanin levels, introducing a potential diagnostic and/or therapeutic target for patients with coronary endothelial function.
AJP Heart and Circulatory Physiology 12/2012; · 4.01 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Context:GH receptor (GHR) exon 3-deleted/full-length (d3/fl) polymorphism has been proposed to affect the responsiveness to GH therapy. Conventional multiplex PCR genotyping method for this polymorphism detection requires DNA samples, which may be difficult to obtain due to ethical and procedural issues and may limit further studies into the role of this polymorphism in health and disease.Objective:The objective of the study was to develop a simple genotyping-alternative method for GHRd3 identification by directly measuring serum levels of total GH binding protein (tGHBP) and exon 3-positive GHBP[(E3((+))GHBP] by immunoassay and thereby assess the GHRd3 status.Design:The GHRd3 genotype was determined by PCR, and tGHBP and E3((+))GHBP levels were measured in serum of 88 healthy adults.Main Outcome Measures:The GHRd3 chemotype by ELISA was compared with the genotype by conventional PCR.Results:The concordance rate of GHR exon 3 status identification between PCR genotyping and ELISA chemotyping was shown to be 100%. There were negligible detectable serum levels of E3((+))GHBP in d3/d3 subjects. The ratio of serum levels E3((+))GHBP vs. tGHBP in fl/fl and d3/fl subjects was (mean ± sd) 96.6 ± 5.1 and 57.1 ± 8.4%, respectively (P < 0.0001). Interestingly, we observed that d3/d3 subjects had significantly lower serum levels of tGHBP compared with fl/fl and d3/fl genotypes.Conclusions:This dual ELISA against tGHBP and E3((+))GHBP can be used as an alternative method for determining GHRd3 polymorphism status. The implications of differences in serum levels of tGHBP among different genotypes and responsiveness to GH therapy need to be further investigated.
The Journal of Clinical Endocrinology and Metabolism 11/2012; · 6.31 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Insulin-like growth factor binding protein-3 (IGFBP-3) is a pro-apoptotic, anti-metastasic, and anti-angiogenic protein. Low serum IGFBP-3 has been associated with risk of more aggressive prostate cancer (PCa). We investigated the impact of nuclear and cytoplasmic IGFBP-3 protein expression levels in PCa by examining their in situ expression across a wide spectrum of primary tumors by immunohistochemical analysis of tissue microarrays. Immunohistochemistry was performed on PCa microarrays constructed from 226 hormone naïve patients who underwent radical prostatectomy. Both cytoplasmic and nuclear IGFBP-3 expressions were scored in a semi-quantitative fashion using an integrated measure of intensity and positivity. The distribution of IGFBP-3 protein expression was examined across the spectrum of epithelial tissues, and its association with standard clinicopathological covariates and tumor recurrence was examined. There was a broad range of IGFBP-3 staining across all histologies examined. Tumor had higher IGFBP-3 cytoplasmic and nuclear staining than benign histologies. For IGFBP-3 nuclear staining, PCa was significantly different than benign prostatic hyperplasia, normal prostate, and prostate intraepithelial neoplasia. As both a continuous and dichotomized variable, higher nuclear IGFBP-3 expression had statistically significant associations with PCa recurrence. The cytoplasmic staining had no significance in any patient subgroup. In patients with low-grade cancer, IGFBP-3 nuclear positivity was a better predictor of recurrence than baseline PSA, tumor margin status, TNM tumor stage, or presence of capsular invasion. High nuclear IGFBP-3 is amongst the strongest predictors of cancer recurrence in patients with low-grade prostate cancers and may therefore play an important role in risk stratification.
[Show abstract][Hide abstract] ABSTRACT: Humanin (HN) is an endogenous mitochondrial-derived cytoprotective peptide that has shown protective effects against atherosclerosis and is expressed in human vessels. However, its effects on the progression of kidney disease are unknown. We hypothesized that HN would protect the kidney in the early phase of atherogenesis.
Forty-eight mice were studied in four groups (n=12 each). Twenty-four ApoE deficient mice were fed a 16-week high-cholesterol diet supplemented with saline or HN (4mg/kg/day, intraperitoneal). C57BL/6 mice were fed a normal diet supplemented with saline or HN. Microvascular architecture was assessed with micro-CT and vascular wall remodeling by alpha-SMA staining. The effects of HN on angiogenesis, inflammation, apoptosis and fibrosis were evaluated in the kidney tissue by Western blotting and histology.
Cortical microvascular spatial density and media/lumen area ratio were significantly increased in high-cholesterol diet fed ApoE deficient mice, but restored by HN. HN up-regulated the renal expressions of anti-angiogenic proteins angiostatin and TSP-1, and inhibited angiopoietin-1. HN attenuated inflammation by down-regulating MCP-1, TNF-alpha and osteopontin. HN also tended to restore pSTAT3 and attenuated Bax expression, suggesting blunted apoptosis. Kidney collagen IV expression was alleviated by HN treatment.
HN attenuates renal microvascular remodeling, inflammation and apoptosis in the early stage of kidney disease in hypercholesterolemic ApoE(-/-) mice. HN may serve as a novel therapeutic target to mitigate kidney damage in early atherosclerosis.
Life sciences 07/2012; 91(5-6):199-206. · 2.56 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: In preclinical models, both dietary fat reduction and insulin-like growth factor I receptor (IGF-1R) blockade individually inhibit prostate cancer xenograft growth. We hypothesized that a low-fat diet combined with IGF-1R blockade would cause additive inhibition of prostate cancer growth and offset possible untoward metabolic effects of IGF-1R blockade antibody therapy. Fifty severe combined immunodeficient mice were injected with 22Rv1 cells subcutaneously. Ten days postinjection, the animals were randomized to four groups: (i) high-fat diet + saline (HF); (ii) high-fat diet + IGF-1R blocking antibody, ganitumab (HF/Ab); (iii) low-fat diet + saline (LF); and (iv) low-fat diet + ganitumab (LF/Ab). After 19 days of treatment, the animals were euthanized, serum was collected, and tumors were weighed. Tumor Ki67, Akt and extracellular signal-regulated kinase (ERK) activation, serum insulin, IGF-I and TNF-α were measured. In vitro, ganitumab treatment inhibited growth and induced apoptosis in several prostate cancer cell lines. In vivo, tumor weights and volumes were unaffected by the different treatments. The LF/Ab therapy significantly reduced proliferation (Ki67) and ERK activation in tumors. The HF/Ab group had significantly higher serum insulin levels than the HF group. However, LF/Ab combination significantly reduced serum insulin back to normal levels as well as normalizing serum TNF-α level. Whereas the combination of low-fat diet and IGF-1R blockade did not have additive inhibitory effects on tumor weight, it led to reduced tumor cell proliferation and a reduction in serum insulin and TNF-α levels.
Molecular Cancer Therapeutics 05/2012; 11(7):1539-46. · 5.60 Impact Factor