The GH-IGF-I axis and breast cancer

Role of a Whole Plant Foods Diet in Breast Cancer Prevention and Survival

Breast cancer (BC) is one of the leading causes of death and morbidity among women worldwide. Epidemiologic evidence shows that the risk of BC and other chronic diseases decreases as the proportion of whole plant foods increases, while the proportion of animal foods (fish, meat, poultry, eggs, seafood, and dairy products) and non-whole plant foods (e.g., refined grains, added sugars, French fries) in the diet decreases. Whole plant foods include fruits, vegetables, roots, tubers, whole grains, legumes, nuts, and seeds from which no edible part has been removed and to which no non-whole food been added. A whole plant foods diet lowers insulin resistance, inflammation, excess body fat, cholesterol, and insulin-like growth factor 1 and sex hormone bioavailability; it also increases estrogen excretion, induces favorable changes in the gut microbiota, and may also favorably affect mammary microbiota composition and decrease the risk of early menarche, all contributing to reduced BC incidence, recurrence, and mortality. This review explores the connection between a whole plant foods diet and BC risk and mortality as well as the potential mechanisms involved. Additionally, this diet is compared with other dietary approaches recommended for BC. A whole plant foods diet seems the optimal dietary pattern for BC and overall disease prevention as it exclusively consists of whole plant foods which, based on existing evidence, lead to the best health outcomes.

Biosynthesis of a water solubility-enhanced succinyl glucoside derivative of luteolin and its neuroprotective effect

The natural flavonoids luteolin and luteoloside have anti-bacterial, anti-inflammatory, anti-oxidant, anti-tumour, hypolipidemic, cholesterol lowering and neuroprotective effects, but their poor water solubility limits their application in industrial production and the pharmaceutical industry. In this study, luteolin-7-O-β-(6″-O-succinyl)-d-glucoside, a new compound that was prepared by succinyl glycosylation of luteolin by the organic solvent tolerant bacterium Bacillus amyloliquefaciens FJ18 in an 8.0% DMSO (v/v) system, was obtained and identified. Its greater water solubility (2293 times that of luteolin and 12 232 times that of luteoloside) provides the solution to the application problems of luteolin and luteoloside. The conversion rate of luteolin (1.0 g l^-1 ) was almost 100% at 24 h, while the yield of luteolin-7-O-β-(6″-O-succinyl)-d-glucoside reached 76.2%. In experiments involving the oxygen glucose deprivation/reoxygenation injury model of mouse hippocampal neuron cells, the cell viability was significantly improved with luteolin-7-O-β-(6″-O-succinyl)-d-glucoside dosing, and the expressions of the anti-oxidant enzyme HO-1 in the nucleus increased, providing a neuroprotective effect for ischemic cerebral cells. The availability of biosynthetic luteolin-7-O-β-(6″-O-succinyl)-d-glucoside, which is expected to replace luteolin and luteoloside, would effectively expand the clinical application value of luteolin derivatives.

Effect of Type of Pregnancy on Transcriptional and Plasma Metabolic Response in Sheep and Its Further Effect on Progeny Lambs

Simple Summary

The present study was carried out in order to determine the effect of type of pregnancy on the mammary gland development, evaluated through the transcriptional expression of genes that are associated to angiogenesis and cell turnover/lactogenesis and the metabolic response of the animals. For this, six twin and seven single-bearing ewes were fed with naturalized pasture from day −45 pre-partum until day +70 post-partum, taking samples of mammary tissue and plasma at different times from the birth until weaning. The results showed the type of pregnancy could only explain a few differences in the transcriptional expression of in some genes that are involved in angiogenesis and cell turnover/lactogenesis in the mammary gland tissue, which had no impact on the metabolic status of ewes or the metabolic response in plasma, performance, and muscle transcriptional expression of the lambs.

Abstract

The following study was performed in order to determine the effect of type of pregnancy on the transcriptional expression of genes that are engaged in angiogenesis and cell turnover/lactogenesis in the ewe mammary gland, evaluating its impact on the plasma metabolic response. In addition, an assessment of its further influence on plasma metabolic response, performance, and muscle transcriptional expression of lipogenic enzymes in progeny lambs was made. Thirteen Ile de France sheep (six twin- and seven single-bearing ewes) were allocated to graze ad libitum naturalized pasture from d 45 pre-partum to day 70 post-partum, while keeping their lambs on the same diet until day 60 after weaning. The samples were collected at different times and analyzed by qRT-PCR and plasma metabolic indicators. The data were processed using SPSS package. The results showed that twin-bearing ewes overexpressed VEGFR1 at birth, and BCL2 at birth and day 35 post-partum; however, single-bearing ewes overexpressed CAIV and IGF1 at day 35 post-partum. Similar metabolite concentrations in blood plasma were found between groups of ewes. The plasma metabolic response in lambs was similar between groups and it did not influence their performance, where a similar transcriptional expression of lipogenic enzymes in muscle was observed. Therefore, the type of pregnancy can explain the slight differences in mRNA expression that were found in angiogenesis and cell turnover/lactogenesis in mammary gland, although these differences not only did not affect the plasma metabolic response in ewes, but they also had no influence on plasma metabolic response, performance, and muscle transcriptional expression of their lambs.

Targeting IRS-1/mPGES-1/NOX2 to inhibit the inflammatory response caused by insulin-like growth factor-I-induced activation of NF-κB and NLRP3 in cancer cells

The levels of insulin-like growth factor-l (IGF-1) and reactive oxygen species (ROS) are abnormally elevated in various tumour tissues, and IGF-1 has been reported to be associated with the development and progression of inflammation in cancers. In this study, we found that IGF-1 activated nuclear factor-κB (NF-κB) and NLRP3 inflammatory signalling via IRS-1/mPGES-1/NOX2-regulated ROS. Additionally, in the B16-F10 tumour-bearing mouse model, the number of tumours, tumour growth, invasion of tissues and expression of proinflammatory factors in peripheral blood were significantly decreased by treatment with an inhibitor combination compared with those of the IGF-1 group. Taken together, targeting IRS-1/mPGES-1/NOX2 to inhibit inflammation related to NF-κB and NLRP3 is a potential strategy for controlling the development and progression of cancer.

Pyrosequencing analysis of IRS1 methylation levels in schizophrenia with tardive dyskinesia

Tardive dyskinesia (TD) is a serious side effect of certain antipsychotic medications that are used to treat schizophrenia (SCZ) and other mental illnesses. The methylation status of the insulin receptor substrate 1 (IRS1) gene is reportedly associated with SCZ; however, no study, to the best of the authors' knowledge, has focused on the quantitative DNA methylation levels of the IRS1 gene using pyrosequencing in SCZ with or without TD. The present study aimed to quantify DNA methylation levels of 4 CpG sites in the IRS1 gene using a Chinese sample including SCZ patients with TD and without TD (NTD) and healthy controls (HCs). The general linear model (GLM) was used to detect DNA methylation levels among the 3 proposed groups (TD vs. NTD vs. HC). Mean DNA methylation levels of 4 CpG sites demonstrated normal distribution. Pearson's correlation analysis did not reveal any significant correlations between the DNA methylation levels of the 4 CpG sites and the severity of SCZ. GLM revealed significant differences between the 3 groups for CpG site 1 and the average of the 4 CpG sites (P=0.0001 and P=0.0126, respectively). Furthermore, the TD, NTD and TD + NTD groups demonstrated lower methylation levels in CpG site 1 (P=0.0003, P<0.0001 and P<0.0001, respectively) and the average of 4 CpG sites (P=0.0176, P=0.0063 and P=0.003, respectively) compared with the HC group. The results revealed that both NTD and TD patients had significantly decreased DNA methylation levels compared with healthy controls, which indicated a significant association between the DNA methylation levels of the IRS1 gene with SCZ and TD.

Effect of in ovo feeding of β-hydroxy-β-methylbutyrate on hatchability, muscle growth and performance in prenatal and posthatch broilers

BACKGROUND

β-Hydroxy-β-methylbutyrate (HMB) is the metabolite of leucine that plays an important role in muscle protein metabolism. The objective of the present study was to determine the effects of in ovo feeding (IOF) of HMB at 7 days of incubation (DOI) via air cell or 18 DOI via amnion on hatchability, muscle growth and performance in prenatal and posthatch broilers.

RESULTS

IOF of HMB via air cell at 7 DOI increased hatchability by 4.34% compared with the control (89.67% versus 85.33%). Birds in IOF groups exhibited higher body weight, average daily body weight gain and pectoral muscle percentage. Furthermore, IOF of HMB significantly increased the level of plasma growth hormone, insulin and insulin-like growth factor-1. Chicks hatched from IOF treatment had larger diameters of muscle fiber and higher mitotic activity of satellite cells at early posthatch age. IOF of HMB activated satellite cells by upregulation of mRNA expression of myogenic transcription factors, myogenic differentiation one (MyoD) and myogenin. Chicks hatched from air cell injection group had higher pectoral muscle percentage at 5 d posthatch and greater satellite cell mitotic activity at 7 d posthatch than counterparts from amnion injection group.

CONCLUSIONS

IOF of HMB via amnion at 18 DOI or especially via air cell at 7 DOI could be used as an effective approach to enhance hatchability, productive performance and breast muscle yield in broilers. © 2019 Society of Chemical Industry.

Screening for Multiple Autoantibodies in Plasma of Patients with Breast Cancer

BACKGROUND/AIM

Autoantibodies have potential as circulating biomarkers for early cancer detection. This study aimed to screen for known autoantibodies in human plasma using an Autoantibody Profiling System (APS) and quantify the levels in plasma of donors with/without breast cancer.

MATERIALS AND METHODS

Plasma from nine female donors diagnosed with breast cancer (test group) and nine matched donors with no personal history of cancer (reference group) were screened with an APS containing probes for 30 autoantibodies. Autoantibody levels ≥1.5 times the mean concentration of the group were considered elevated, and test/reference ratios ≥1.3 were considered higher in the test group compared to the reference group.

RESULTS

Twenty percent of the probes detected elevated levels of autoantibodies against proteins involved in different cancer mechanisms. Amongst these, the levels of autoantibodies against interleukin 29 (IL29), osteoprotegerin (OPG), survivin (SUR), growth hormone (GRH) and resistin (RES) were significantly higher in the cancer group compared to the reference group (p<0.05), whereas the level of autoantibody against cytotoxic T-lymphocyte associated antigen-4 (CTLA4) was not significantly different between the two groups (p=0.38).

CONCLUSION

Disease-relevant autoantibodies were detected in the plasma of patients with breast cancer and donors without breast cancer. This means that identifying the type and level of autoantibodies in samples will be important in determining their significance in the disease process. A microtiter plate-based array system could be a fast and inexpensive screening method for identifying and quantifying autoantibodies in human plasma.

Influence of Recombinant Human Growth Hormone (rhGH) on Proliferation of Hepatocellular Carcinoma Cells with Positive and Negative Growth Hormone Receptorsin Vitro

Aims and background

Recombinant human growth hormone (rhGH) is increasingly used in the clinic because it promotes the synthesis of proteins. However, rhGH is able to increase malignant transformation and tumor recurrence. The aim of this study was to investigate the effects of rhGH on hepatocellular carcinoma (HCC) cells with positive and negative growth hormone receptors (GHR) in order to guide its clinical application.

Methods and study design

Cells of the human HCC cell lines Bel-7402 (GHR+) and SMMC-7721 (GHR-) as well as human umbilical vein endothelial cell line ECV304 cells in the exponential growth phase were harvested and divided into experimental and control groups. After the human HCC cells were cultured alone or co-cultured with ECV304 cells under the different treatments, cell cycle phase, proliferation index, and expression levels of vascular endothelial growth factor (VEGF) mRNA and proteins were determined.

Results

In the Bel-7402 GHR+ cells treated with rhGH, both the percentage of cell in G2-M phase and the proliferation index were higher than those of controls (P <0.05); this was not the case in the SMMC-7721 GHR- cells treated with rhGH (P >0.05). Although there was no difference in the cell doubling times between ECV304 cells co-incubated with Bel-7721 GHR- cells treated with rhGH and without rhGH, the doubling times of ECV304 cells co-incubated with Bel-7402 GHR+ cells, when treated with rhGH, were significantly shortened compared to those of controls (P <0.05). The cell doubling times of ECV304 cells co-incubated with Bel-7721 GHR- or Bel-7402 GHR+ cells which were treated with bevacizumab were longer than those of controls and of cells with rhGH (P <0.05). The VEGF mRNA and protein expression levels were higher in Bel-7402 GHR+ cells treated with different doses of rhGH than controls (P <0.05 or P <0.01); however, there was no statistically significant difference in the expression levels of VEGF mRNA and proteins between SMMC-7721 GHR- cells treated with rhGH and controls.

Conclusions

rhGH can induce VEGF secretion and stimulate proliferation of Bel-7402 GHR+ cells in vitro, but has little effect on the proliferation of SMMC-7721 GHR-cells, suggesting that rhGH may be applied safely to treatment for the catabolic state in patients with GHR-negative HCC.

Role of Growth Hormone in Breast Cancer

Breast cancer is one of the most common cancers diagnosed in women. Approximately two-thirds of all breast cancers diagnosed are classified as hormone dependent, which indicates that hormones are the key factors that drive the growth of these breast cancers. Ovarian and pituitary hormones play a major role in the growth and development of normal mammary glands and breast cancer. In particular, the effect of the ovarian hormone estrogen has received much attention in regard to breast cancer. Pituitary hormones prolactin and growth hormone have also been associated with breast cancer. Although the role of these pituitary hormones in breast cancers has been studied, it has not been investigated extensively. In this review, we attempt to compile basic information from most of the currently available literature to understand and demonstrate the significance of growth hormone in breast cancer. Based on the available literature, it is clear that growth hormone plays a significant role in the development, progression, and metastasis of breast cancer by influencing tumor angiogenesis, stemness, and chemoresistance.

PQ401, an IGF-1R inhibitor, induces apoptosis and inhibits growth, proliferation and migration of glioma cells

Growth factor signalling pathways transduce extra-cellular physiological cues to guide cells to maintain critical cellular functions, including cell proliferation, survival and metabolism. Dysregulation of certain growth factor signalling pathways has been shown as a major route to promote tumourigenesis. Glioma is a type of aggressive malignant tumour with no effective systematic therapy so far. Overexpression or hyperactivation of IGF-1R has been observed to be tightly associated with glioma progression and poor prognosis. Here, we examined the biological effects of a specific IGF-1R inhibitor, PQ401, on suppressing U87MG glioma cell growth and migration. Specifically, we observed that PQ401 not only induced cellular apoptosis in U87MG cells and subsequently reduced cell viability and proliferation but also attenuated cell mobility in vitro. More importantly, through a mouse xenograft model, we observed that administration of PQ401 on mice led to suppression of glioma tumour growth in vivo. In summary, our study suggests that PQ401 may serve as a promising leading drug for treating glioma patients with elevated IGF-1R signalling.

Association between IRS1 Gene Polymorphism and Autism Spectrum Disorder: A Pilot Case-Control Study in Korean Males

The insulin-like growth factor (IGF) pathway is thought to play an important role in brain development. Altered levels of IGFs and their signaling regulators have been shown in autism spectrum disorder (ASD) patients. In this study, we investigated whether coding region single-nucleotide polymorphisms (cSNPs) of the insulin receptor substrates (IRS1 and IRS2), key mediators of the IGF pathway, were associated with ASD in Korean males. Two cSNPs (rs1801123 of IRS1, and rs4773092 of IRS2) were genotyped using direct sequencing in 180 male ASD patients and 147 male control subjects. A significant association between rs1801123 of IRS1 and ASD was shown in additive (p = 0.022, odds ratio (OR) = 0.66, 95% confidence interval (CI) = 0.46–0.95) and dominant models (p = 0.013, OR = 0.57, 95% CI = 0.37–0.89). Allele frequency analysis also showed an association between rs1801123 and ASD (p = 0.022, OR = 0.66, 95% CI = 0.46–0.94). These results suggest that IRS1 may contribute to the susceptibility of ASD in Korean males.

Usefulness of IGF-1 serum levels as diagnostic marker of nasopharyngeal carcinoma

BACKGROUND

The role of IGF-1 in promoting cancer has been investigated for many years. The aim of this study is to explore the relationship between rates of IGF-1 and NPC and to evaluate association of IGF-1 with clinical parameters.

MATERIALS AND METHODS

IGF-1 levels was measured by Elisa test among 82 NPC patients and 60 healthy controls

RESULTS

Our results showed, for the first time, a significant increased levels of IGF-I in NPC by in comparison with healthy controls (p<0.01). According to the age, sex and tumor size of NPC patients, we demonstrated that IGF-1 concentrations are significantly higher in NPC aged over 30 years compared to patients aged less than 30 years (p<0.01). The IGF-1 levels are, also, higher among women compared to men (p<0.01). The concentrations of IGF-1 were positively correlated with tumor size of NPC patients (p<0.01).

CONCLUSION

IGF-I could be a good nasopharyngeal cancer diagnostic marker.

A polymorphic repeat in the IGF1 promoter influences the risk of endometrial cancer

Due to the lack of high-throughput genetic assays for tandem repeats, there is a paucity of knowledge about the role they may play in disease. A polymorphic CA repeat in the promoter region of the insulin-like growth factor 1 gene (IGF1 has been studied extensively over the past 10 years for association with the risk of developing breast cancer, among other cancers, with variable results. The aim of this study was to determine if this CA repeat is associated with the risk of developing breast cancer and endometrial cancer. Using a case-control design, we analysed the length of this CA repeat in a series of breast cancer and endometrial cancer cases and compared this with a control population. Our results showed an association when both alleles were considered in breast and endometrial cancers (P=0.029 and 0.011, respectively), but this did not pass our corrected threshold for significance due to multiple testing. When the allele lengths were analysed categorically against the most common allele length of 19 CA repeats, an association was observed with the risk of endometrial cancer due to a reduction in the number of long alleles (P=0.013). This was confirmed in an analysis of the long alleles separately for endometrial cancer risk (P=0.0012). Our study found no association between the length of this polymorphic CA repeat and breast cancer risk. The significant association observed between the CA repeat length and the risk of developing endometrial cancer has not been previously reported.

Genetic polymorphisms of insulin-like growth factor 1 and insulin-like growth factor binding protein 3, xenoestrogen, phytoestrogen, and premenopausal breast cancer

BACKGROUND

Previous studies suggest a combined effect of insulin-like growth factor 1 (igf-1) and igf binding protein 3 (igfbp-3) gene polymorphisms, xenoestrogen, and phytoestrogen on the igf-1 signalling pathway and serum concentrations in the igf system, which are associated with premenopausal breast cancer (bca) risk.

METHODS

Between 2010 and 2012, our study recruited 140 premenopausal bca patients and 160 community-based premenopausal control subjects. Participants were surveyed about oral contraceptive (oc) use, dietary habits, and other bca risk factors. TaqMan assays were used to determine igf-1 rs1520220 and igfbp-3 rs2854744 genotypes. Daily intakes of energy-adjusted soy isoflavones (easis) were calculated by the residual method. Multivariate logistic regression was applied to estimate the adjusted odds ratios (ors) and 95% confidence intervals (cis) of the igf-1 rs1520220 and igfbp-3 rs2854744 genotypes, oc use, and intake of easis. Stratified analyses were performed to detect the gene-environment combined effect, and multivariate logistic regression was used to estimate interaction coefficients (iors) by the multiplicative model, with 95% cis. The delta method was used to calculate interaction coefficients by the additive model [relative excess risk of interaction (reri), attributable proportions of interaction (apis)] and 95% cis.

RESULTS

The igf-1 and igfbp-3 genotypes, oc use, and easis were not found to be associated with bca risk (p > 0.05). Stratified analysis showed that the risk of bca was markedly increased in women carrying the igfbp-3C allele and using ocs compared with women either carrying the igfbp-3C allele or using ocs (or: 3.02; 95% ci: 1.04 to 8.79). The interaction coefficients ior, reri, and api were 4.89 (95% ci: 1.09 to 21.90), 2.42 (95% ci: -0.76 to 5.61), and 0.80 (95% ci: 0.46 to 1.67) respectively.

CONCLUSIONS

The igfbp-3 rs2854744 polymorphism and oc use might synergistically increase premenopausal bca risk.

Antitumor and biological investigation of doubly cyclometalated ruthenium(ii) organometallics derived from benzimidazolyl derivatives

In this study, we report the synthesis, anticancer and biological properties of three doubly cyclometalated phenylbenzimidazole derived ruthenium(ii) organometallics (1–3) and their corresponding three organic ligands.

Autocrine human growth hormone stimulates the tumor initiating capacity and metastasis of estrogen receptor-negative mammary carcinoma cells

The oncogenic effects of autocrine human growth hormone (hGH) have been intensively investigated in estrogen receptor-positive mammary carcinoma (ER + MC) cells. We demonstrated herein that autocrine hGH promoted cancer stem cell (CSC)-like properties of estrogen receptor-negative mammary carcinoma (ER-MC) cells in vitro. In xenograft studies, autocrine hGH increased the tumor initiating capacity of ER-MC cells. We also observed that autocrine hGH promoted migration and invasion of ER-MC cells in vitro, and metastasis in vivo. Thus, inhibition of hGH is a potential therapeutic strategy to prevent tumor initiation and metastasis of ER-MC.

Obesity alters gene expression for GH/IGF-I axis in mouse mammary fat pads: differential role of cortistatin and somatostatin

Locally produced growth hormone (GH) and IGF-I are key factors in the regulation of mammary gland (MG) development and may be important in breast cancer development/progression. Somatostatin (SST) and cortistatin (CORT) regulate GH/IGF-I axis at various levels, but their role in regulating GH/IGF-I in MGs remains unknown. Since obesity alters the expression of these systems in different tissues and is associated to MG (patho) physiology, we sought to investigate the role of SST/CORT in regulating GH/IGF-I system in the MGs of lean and obese mice. Therefore, we analyzed GH/IGF-I as well as SST/CORT and ghrelin systems expression in the mammary fat pads (MFPs) of SST- or CORT-knockout (KO) mice and their respective littermate-controls fed a low-fat (LF) or a high-fat (HF) diet for 16 wks. Our results demonstrate that the majority of the components of GH/IGF-I, SST/CORT and ghrelin systems are locally expressed in mouse MFP. Expression of elements of the GH/IGF-I axis was significantly increased in MFPs of HF-fed control mice while lack of endogenous SST partially suppressed, and lack of CORT completely blunted, the up-regulation observed in obese WT-controls. Since SST/CORT are known to exert an inhibitory role on the GH/IGFI axis, the increase in SST/CORT-receptor sst2 expression in MFPs of HF-fed CORT- and SST-KOs together with an elevation on circulating SST in CORT-KOs could explain the differences observed. These results offer new information on the factors (GH/IGF-I axis) involved in the endocrine/metabolic dysregulation of MFPs in obesity, and suggest that CORT is not a mere SST sibling in regulating MG physiology.

The GH-IGF-SST system in hepatocellular carcinoma: biological and molecular pathogenetic mechanisms and therapeutic targets

Hepatocellular carcinoma (HCC) is the sixth most common malignancy worldwide. Different signalling pathways have been identified to be implicated in the pathogenesis of HCC; among these, GH, IGF and somatostatin (SST) pathways have emerged as some of the major pathways implicated in the development of HCC. Physiologically, GH-IGF-SST system plays a crucial role in liver growth and development since GH induces IGF1 and IGF2 secretion and the expression of their receptors, involved in hepatocytes cell proliferation, differentiation and metabolism. On the other hand, somatostatin receptors (SSTRs) are exclusively present on the biliary tract. Importantly, the GH-IGF-SST system components have been indicated as regulators of hepatocarcinogenesis. Reduction of GH binding affinity to GH receptor, decreased serum IGF1 and increased serum IGF2 production, overexpression of IGF1 receptor, loss of function of IGF2 receptor and appearance of SSTRs are frequently observed in human HCC. In particular, recently, many studies have evaluated the correlation between increased levels of IGF1 receptors and liver diseases and the oncogenic role of IGF2 and its involvement in angiogenesis, migration and, consequently, in tumour progression. SST directly or indirectly influences tumour growth and development through the inhibition of cell proliferation and secretion and induction of apoptosis, even though SST role in hepatocarcinogenesis is still opened to argument. This review addresses the present evidences suggesting a role of the GH-IGF-SST system in the development and progression of HCC, and describes the therapeutic perspectives, based on the targeting of GH-IGF-SST system, which have been hypothesised and experimented in HCC.

Growth hormone is secreted by normal breast epithelium upon progesterone stimulation and increases proliferation of stem/progenitor cells

Using in vitro and in vivo experimental systems and in situ analysis, we show that growth hormone (GH) is secreted locally by normal human mammary epithelial cells upon progesterone stimulation. GH increases proliferation of a subset of cells that express growth hormone receptor (GHR) and have functional properties of stem and early progenitor cells. In 72% of ductal carcinoma in situ lesions, an expansion of the cell population that expresses GHR was observed, suggesting that GH signaling may contribute to breast cancer development.

Increased genome instability and oxidative DNA damage and their association with IGF-1 levels in patients with active acromegaly

OBJECTIVE

The objectives of this study were to assess cytokinesis-block micronucleus cytome (CBMN Cyt) assay parameters and also oxidative DNA damage in patients with active acromegaly and controls and to assess the relationship between age, serum insulin-like growth factor 1 (IGF-1) levels, pituitary adenoma diameters, 8-hydroxy-2'-deoxyguanosine (8-OHdG) levels and CBMN Cyt assay parameters in patients with active acromegaly.

DESIGN

The study population included 30 patients with active acromegaly and 30 age- and sex-matched healthy controls. CBMN Cyt assay parameters in peripheral blood lymphocytes of patients with active acromegaly and controls were evaluated and plasma 8-OHdG levels were measured.

RESULTS

Frequencies of micronucleus (MN), nucleoplasmic bridges (NPBs) and nuclear buds (NBUDs) in lymphocytes of patients with acromegaly were found to be significantly higher than those in controls (p<0.001, p<0.001, p<0.001, respectively). The frequencies of apoptotic and necrotic cells in lymphocytes of patients with acromegaly were found to be significantly higher than those in controls (p<0.001 and p<0.001 respectively). No statistically significant differences in the number of cells in metaphase, the number of bi-nucleated cells (M2), the number of tri-nucleated cells (M3), the number of tetra-nucleated cells (M4) and nuclear division index (NDI) values were observed between patients and controls (p>0.05). Plasma 8-OHdG (ng/ml) levels in patients with acromegaly were found to be significantly higher than those in controls (p<0.005). MN frequency in the lymphocytes of patients with acromegaly increased with elevated serum IGF-1 levels (p<0.05), whereas the number of NPBs and the frequency of apoptotic cells decreased with elevated serum IGF-1 levels (p<0.01 and p<0.05 respectively).

CONCLUSIONS

Both the increase in chromosomal/oxidative DNA damage and the positive association between MN frequency and serum IGF-1 levels may predict an increased risk of malignancy in acromegalic patients. Long-term follow-up of patients with acromegaly will be necessary to establish the degree of cancer risk in this population.

Prognosis of pregnancy-associated breast cancer: a meta-analysis of 30 studies

BACKGROUND

Pregnancy-associated breast cancer (PABC) is relatively rare with considerable controversy regarding its prognosis.

PATIENTS & METHODS

Two of the authors independently performed a literature search with no date or language restrictions. Eligible studies were control-matched, population-based and hospital-based studies that addressed the outcome of patients diagnosed during pregnancy or 1-year afterwards. The primary and secondary end-points were overall and disease-free survival respectively. Pooling of data was done using the random effect model.

RESULTS

30 studies were included in this meta-analysis (3,628 cases and 37,100 controls). PABC patients had a significantly higher risk of death compared to those with non-pregnancy-related breast cancer (pooled hazard ratio (pHR): 1.44; 95% CI [1.27-1.63]). The same results were encountered on restricting the analysis to HRs of multivariate analyses (pHR: 1.40 [1.17-1.67]). A clearer trend of poorer outcome was seen in those diagnosed postpartum (pHR: 1.84; 95% CI [1.28-2.65]) than those diagnosed during pregnancy (pHR: 1.29; 95% CI [0.74-2.24]). DFS analysis showed a significantly higher risk of relapse associated with PABC as well (pHR: 1.60 [1.19-2.16]).

CONCLUSION

Our results show that PABC is independently associated with poor survival particularly those diagnosed shortly post-partum. This underscores a possible impact of the pregnant breast microenvironment on the biology and consequently the prognosis of these tumors.

Mammary cancer promotion by ovarian hormones involves IGFR/AKT/mTOR signaling

In a previous study, we observed that N-methyl-N-nitrosourea (MNU)-induced mammary lesions are promoted to overt mammary cancers by exogenous administration of estradiol (E) and progesterone (P). The purpose of the present study was to identify the early molecular events occurring during the hormonal promotion of mammary carcinogenesis and persistent activation of molecular pathways responsible for tumor growth. Seven-week-old female Copenhagen (COP) rats, which are resistant to MNU-induced mammary carcinogenesis, were intraperitoneally administered a single dose of MNU (50 mg/kg body weight). Six weeks after carcinogen administration, the rats were treated with E+P, killed at 15th week and 43rd week to obtain mammary lesions and tumor tissues and the molecular analysis were performed. Quantitative RT-PCR experiments showed increased mRNA expression of Igfr, Grb2, Sos1, and Shc1 in mammary lesions and tumors. Immunoblot data also showed increased protein levels of IGFR, GRB2 and SHC1 in mammary lesions and tumors, which is in correlation with their respective RT-PCR data. Activation of AKT and ERK1/2 were up regulated in E+P treated mammary lesions and tumors. Molecular analysis of mTOR pathway proteins revealed increased phosphorylation of p70S6K and 4EBP1 in the hormone treated tumors indicating the activation of mTOR signaling. E+P treatment reduced the protein expression of BAX and increased BCL2 expression along with down regulation of active caspase 3 and 8. Together, these data demonstrate that ovarian hormones promote the lesions to mammary tumors by enhancing IGFR and Akt/mTOR signaling along with inhibition of apoptotic stimuli.

Expression of ghrelin is correlated to a favorable outcome in invasive breast cancer

BACKGROUND

Expression of the peptide hormones ghrelin and obestatin has previously been demonstrated in human mammary glands. However, the clinical implications of the expression of these peptides in breast cancer are unclear. The aim of this study was to investigate the potential clinical value of ghrelin and obestatin as breast cancer biomarkers.

METHODS

A tissue microarray containing breast cancer specimens from 144 patients was immunostained with antibodies directed towards ghrelin and obestatin. Using varying cut-offs, the expression of the two peptides was evaluated and correlated to previously known prognostic factors in breast cancer and to the outcome. Cox regression analysis was used to assess whether these markers may predict survival of breast cancer patients.

RESULTS

Moderate to strong immunoreactivity for ghrelin and obestatin was observed in 71.5% and 77.1% of the cases, respectively. Ghrelin and obestatin expression was significantly but weakly correlated to low histological grade, estrogen receptor positivity, small tumor size and low proliferation. Only ghrelin expression was significantly correlated to better recurrence-free and breast cancer-specific survival (HR = 0.3-0.4, p = 0.02-0.05) in both uni- and multivariate analyses. The optimal cut-off was any ghrelin expression versus none. Reproducibility between the two readers was very good for both stainings with kappa values of 0.94-1.00.

CONCLUSIONS

Patients with tumors expressing ghrelin had 2.5-3 times lower risk for recurrence or breast cancer death than those lacking ghrelin expression. Ghrelin expression is easily assessable with high reproducibility using immunohistochemistry. Further investigations are needed to establish the clinical significance of ghrelin as a biomarker in breast cancer.

Hyperinsulinemia enhances c-Myc-mediated mammary tumor development and advances metastatic progression to the lung in a mouse model of type 2 diabetes

INTRODUCTION

Hyperinsulinemia, which is common in early type 2 diabetes (T2D) as a result of the chronically insulin-resistant state, has now been identified as a specific factor which can worsen breast cancer prognosis. In breast cancer, a high rate of mortality persists due to the emergence of pulmonary metastases.

METHODS

Using a hyperinsulinemic mouse model (MKR+/+) and the metastatic, c-Myc-transformed mammary carcinoma cell line Mvt1, we investigated how high systemic insulin levels would affect the progression of orthotopically inoculated primary mammary tumors to lung metastases.

RESULTS

We found that orthotopically injected Mvt1 cells gave rise to larger mammary tumors and to a significantly higher mean number of pulmonary macrometastases in hyperinsulinemic mice over a period of six weeks (hyperinsulinemic, 19.4 ± 2.7 vs. control, 4.0 ± 1.3). When Mvt1-mediated mammary tumors were allowed to develop and metastasize for approximately two weeks and were then surgically removed, hyperinsulinemic mice demonstrated a significantly higher number of lung metastases after a four-week period (hyperinsulinemic, 25.1 ± 4.6 vs. control, 7.4 ± 0.42). Similarly, when Mvt1 cells were injected intravenously, hyperinsulinemic mice demonstrated a significantly higher metastatic burden in the lung than controls after a three-week period (hyperinsulinemic, 6.0 ± 1.63 vs. control, 1.5 ± 0.68). Analysis of Mvt1 cells both in vitro and in vivo revealed a significant up-regulation of the transcription factor c-Myc under hyperinsulinemic conditions, suggesting that hyperinsulinemia may promote c-Myc signaling in breast cancer. Furthermore, insulin-lowering therapy using the beta-adrenergic receptor agonist CL-316243 reduced metastatic burden in hyperinsulinemic mice to control levels.

CONCLUSIONS

Hyperinsulinemia in a mouse model promotes breast cancer metastasis to the lung. Therapies to reduce insulin levels in hyperinsulinemic patients suffering from breast cancer could lessen the likelihood of metastatic progression.

Motherhood after breast cancer: searching for la dolce vita

Advances in the field of adjuvant therapy in breast cancer have led to significant improvements in breast cancer survival. This has resulted in a progressive decline in breast cancer-related mortality, such that in 2010 there were estimated to be 400,000 breast cancer survivors under the age of 40 in the USA. Hence, enquiry into the feasibility of fertility preservation, subsequent pregnancy and breastfeeding is increasingly encountered. Fertility counseling remains suboptimal in breast cancer clinics, and there is a wide perception that pregnancy could worsen the prognosis of young breast cancer survivors, despite the lack of evidence supporting this notion. In addition, fertility preservation by means of embryo or oocyte cryopreservation requires ovarian stimulation, which is associated with a significant rise in estradiol levels and might delay initiation of therapy. All these factors, and others, have influenced the quality of fertility counseling offered to young breast cancer patients. In this article, we will critically analyze the available clinical and biological evidence on the safety and feasibility of pregnancy and breastfeeding following breast cancer. In addition, we will discuss the different fertility-preservation techniques available for these patients.

[Growth hormone receptor antagonist in the treatment of acromegaly]

Exploration of construction, function and interaction of human growth hormone and growth hormone receptor in details resulted in the innovation of the new growth hormone receptor antagonist, pegvisomant. Pegvisomant with different mechanism of action extended the tools of medical management of acromegaly. Importance of the novel treatment modality is high. In one hand the necessity of the strict control of growth hormone/insulin-like growth factor-I axis has been proven regarding the mortality of the disease. On the other hand, despite the use of all current modes of treatment (surgery, radiotherapy, dopamine agonists, somatostatin analogs), a significant cohort of patients with acromegaly remains inadequately controlled. Pegvisomant has been registered in 2004. Since 2006, it has been used in Hungary for the treatment of acromegaly in patients who have had an inadequate response to surgery and/or radiation therapy and/or other medical therapies, or for whom these therapies are not appropriate. Clinical use of pegvisomant in the treatment of acromegaly is effective, well tolerated, and safe, based on international Acrostudy database. In order to improve the efficacy of therapy clinical trials started with pegvisomant and somatostatin analog combination treatment. Evidence of several further effects of the growth hormone/insulin-like growth factor-I axis suggests other potential uses of growth hormone receptor antagonists.

Role of the growth hormone-IGF-1 axis in cancer

A substantial body of evidence supports a role for the growth hormone (GH)-IGF-1 axis in cancer incidence and progression. This includes epidemiological evidence relating elevated plasma IGF-1 to cancer incidence as well as a lack of cancers in GH/IGF-1 deficiency. Rodent models lacking GH or its receptor are strikingly resistant to the induction of a wide range of cancers, and treatment with the GH antagonist pegvisomant slows tumor progression. While GH receptor expression is elevated in many cancers, autocrine GH is present in several types, and overexpression of autocrine GH can induce cell transformation. While the mechanism of autocrine action is not clear, it does involve both STAT5 and STAT3 activation, and probably nuclear translocation of the GH receptor. Development of a more potent GH receptor antagonist or secretion inhibitor is warranted for cancer therapy.

Insulin-like growth factor-1 and childhood cancer risk

Overexpression of growth factors and/or their receptors is a common event in malignancy and provides the underlying mechanisms for one of the hallmarks of cancer, uncontrolled proliferation. Mounting evidence suggests that IGF-1 is involved in the pathogenesis and progression of different types of human cancer such as colon, breast, prostate and lung. However, only a few studies have investigated the association between IGF-1 levels and childhood cancer risk. We aimed to compare the IGF-1 serum level in children with de novo malignancies to healthy children, and to assess its relationship with cancer type, stage, metastasis and different disease characteristics. The study was carried out on 100 children; 50 children with de novo malignancies and 50 healthy children of matched age and gender as a control group. The patients were subjected to a routine work-up for their cancers according to our local standards. Estimation of the serum level of IGF-1 was carried out in the two groups using ELISA. Our results showed that children with cancer had significantly higher levels of IGF-1 than healthy controls of the same age and gender. No association was found between IGF-1 and tumor type, stage, metastasis and other disease characteristics. In conclusion, the IGF-1 serum level is an important indicator of risk for the most prevalent forms of childhood cancer. It may be used to identify children at the highest risk for these cancers and aid in determing who may benefit most from preventive strategies. Given the small number of children in our study, studies with larger populations are required to confirm these results.

Thyroid cancer is the most common cancer associated with acromegaly

The aim of the study was to screen the malignancy in an acromegalic patient group and to determine whether there was any increased risk and the incidence of malignancy and its association with disease characteristics such as duration of disease, latency in diagnosis, and GH and IGF-1 levels. One hundred-five (65 female, 40 male) patients with acromegaly followed and treated at Cerrahpasa Medical School, Endocrinology and Metabolism outpatient clinic between 1983 and 2007 were included in this study. The patients were screened with colonoscopy, mammography, and thyroid and prostate ultrasonography (US). Malignancy was detected in 16 (15%) patients. Thyroid cancer was found in 5 patients (4.7%), breast cancer in 3 (2.8%), colon cancer in 2 (1.9%), lung cancer in 2 (1.9%), cervix cancer in 1 (0.9%), myelodysplastic syndrome (MDS) in 1 (0.9%), cholangiocarcinoma in 1 (0.9%), and multiple endocrine neoplasm (MEN) type 1 in 1 patient (0.9%). Cancer was more common in the male patients (P = 0.046) and high levels of GH increased the risk of cancer development (P = 0.046). In this series, the most commonly detected cancer types were thyroid followed by breast and colon cancers. Although high levels of initial GH seemed to increase the risk of cancer development in acromegalic patients, age, gender, age at the time of diagnosis, duration of disease, and initial IGF-I levels were not associated with cancer development.

Gene regulation by growth hormone

Since the somatomedin hypothesis of growth hormone (GH) action was first formulated more than 50 years ago, the key roles of both GH and insulin-like growth factor-I (IGF-I) in human growth have been extended to include important effects on tissue maintenance and repair. More recent observations have revealed that this pathway has a negative side, as it has been implicated as a potential contributor to the development of several human cancers and has been linked to diminished lifespan in experimental animals. This brief review focuses on fundamental aspects of gene regulation by GH, as long-term hormonal effects all require changes in gene expression. Topics to be discussed include GH-stimulated signal transduction pathways, mechanisms of gene activation and gene repression by GH, and an analysis of control of IGF-I gene transcription by the GH-stimulated transcription factor, signal transducer and activator of transcription (Stat)5b.

Somatostatin and somatostatin receptors: implications for neoplastic growth and cancer biology

Somatostatin agonists (SM-As) are capable of achieving durable symptomatic relief and significant clinical responses in certain tumours. Herein, we review the diverse direct and indirect mechanisms of antineoplastic activity elicited by SM-As as well as the hurdles that complicate their use as monotherapies in a broader range of malignancies. Emphasis is placed on recent clinical attempts to neutralise the IGF-mediated survival factor effects in the bone metastasis microenvironment in advanced prostate cancer. The first clinical trials of this 'anti-survival factor manipulation' strategy utilised the ability of SM-As to suppress the growth hormone-dependent liver-derived IGF-I bioavailability in combination with other drugs, such as dexamethasone, zolendronate and oestrogens, acting systemically and at the bone metastasis microenvironment. These regimens restored androgen ablation responsiveness in stage D3 prostate cancer patients and successfully produced objective clinical responses while only mild toxicities were observed. Furthermore, we focus on the preclinical experimental data of a targeted SM-A coupled to the super-potent doxorubicin derivative AN-201. The resulting conjugate (AN-238) has shown increased antitumour potency with a favourable toxicity profile. The potential use of novel SM-As as anticancer drugs is discussed in relation to data suggesting other direct and indirect treatment approaches pertaining to the somatostatin system.

Distinct alterations in chromatin organization of the two IGF-I promoters precede growth hormone-induced activation of IGF-I gene transcription

Many of the physiological actions of GH are mediated by IGF-I, a secreted 70-residue peptide whose gene expression is induced by GH in the liver and other tissues via mechanisms that remain incompletely characterized but depend on the transcription factor Stat5b. Here we investigate the chromatin landscape of the IGF-I gene in the liver of pituitary-deficient young adult male rats and assess the impact of a single systemic GH injection. Despite minimal ongoing transcription in the absence of GH, both IGF-I promoters appear to reside in open chromatin environments, at least as inferred from relatively high levels of acetylation of core histones H3 and H4 when compared with adjacent intergenic DNA and from enhanced trimethylation of histone H3 at lysine 4. This landscape of open chromatin may reflect maturation of the liver. Surprisingly, in the absence of hormone, IGF-I promoter 1 appears poised to be activated, as evidenced by the presence of the transcriptional coactivator p300 and recruitment of RNA polymerase (Pol) II into a preinitiation complex. By contrast, chromatin surrounding IGF-I promoter 2 is devoid of both p300 and RNA Pol II. Systemic GH treatment causes an approximately 15-fold increase in transcription from each IGF-I promoter within 60 min of hormone administration, leading to a sustained accumulation of IGF-I mRNA. The coordinated induction of both IGF-I promoters by GH is accompanied by hyperacetylation of histones H3 and H4 in promoter-associated chromatin, a decline in monomethylation at lysine 4 of histone H3, and recruitment of RNA Pol II to IGF-I promoter 2. We conclude that GH actions induce rapid and dramatic changes in hepatic chromatin at the IGF-I locus and activate IGF-I gene transcription in the liver by distinct promoter-specific mechanisms: at promoter 1, GH causes RNA Pol II to be released from a previously recruited paused preinitiation complex, whereas at promoter 2, hormone treatment facilitates recruitment and then activation of RNA Pol II to initiate transcription.

Genetic variation and circulating levels of IGF-I and IGFBP-3 in relation to risk of proliferative benign breast disease

Insulin-like growth factor-I (IGF-I) and its major binding protein IGFBP-3 have been implicated in breast carcinogenesis. We examined the associations between genetic variants and circulating levels of IGF-I and IGFBP-3 with proliferative benign breast disease (BBD), a marker of increased breast cancer risk, in the Nurses' Health Study II (NHSII). Participants were 359 pathology-confirmed proliferative BBD cases and 359 matched controls. Circulating IGF-I and IGFBP-3 levels were measured in blood samples collected between 1996 and 1999. Thirty single nucleotide polymorphisms (SNPs) in IGF-I, IGFBP-1, and IGFBP-3 genes were selected using a haplotype tagging approach and genotyped in cases and controls. Circulating IGF-I levels were not associated with proliferative BBD risk. Higher circulating IGFBP-3 levels were significantly associated with increased risk of proliferative BBD (highest vs. lowest quartile odds ratio (OR) [95% confidence interval (CI)], 1.70 (1.06-2.72); p-trend = 0.03). The minor alleles of 2 IGFBP-3 SNPs were associated with lower proliferative BBD risk (homozygous variant vs. homozygous wild-type OR (95% CI): rs3110697: 0.6 (0.4-0.9), p-trend = 0.02; rs2132570: 0.2 (0.1-0.6), p-trend = 0.02). Three other IGFBP-3 SNPs (rs2854744, rs2960436 and rs2854746) were significantly associated with circulating IGFBP-3 levels (p < 0.01). Although these SNPs were not significantly associated with proliferative BBD risk, there was suggestive evidence that the alleles associated with higher circulating IGFBP-3 levels were also associated with higher risk of proliferative BBD. These results suggest that genetic variants and circulating levels of IGFBP-3 may play a role in the early stage of breast carcinogenesis.

Autocrine human growth hormone stimulates oncogenicity of endometrial carcinoma cells

Recent published data have demonstrated elevated levels of human GH (hGH) in endometriosis and endometrial adenocarcinoma. Herein, we demonstrate that autocrine production of hGH can enhance the in vitro and in vivo oncogenic potential of endometrial carcinoma cells. Forced expression of hGH in endometrial carcinoma cell lines RL95-2 and AN3 resulted in an increased total cell number through enhanced cell cycle progression and decreased apoptotic cell death. In addition, autocrine hGH expression in endometrial carcinoma cells promoted anchorage-independent growth and increased cell migration/invasion in vitro. In a xenograft model of human endometrial carcinoma, autocrine hGH enhanced tumor size and progression. Changes in endometrial carcinoma cell gene expression stimulated by autocrine hGH was consistent with the altered in vitro and in vivo behavior. Functional antagonism of hGH in wild-type RL95-2 cells significantly reduced cell proliferation, cell survival, and anchorage-independent cell growth. These studies demonstrate a functional role for autocrine hGH in the development and progression of endometrial carcinoma and indicate potential therapeutic relevance of hGH antagonism in the treatment of endometrial carcinoma.

O hormônio de crescimento na síndrome de Turner: dados e reflexões

A baixa estatura é a principal característica na síndrome de Turner (ST). O agravo estatural na ST é precoce e torna-se mais evidente na puberdade. A haploinsuficiência do gene SHOX tem sido implicada como principal fator na definição da estatura de mulheres, no entanto, ainda que a maioria das pacientes não tenha deficiência do hormônio de crescimento, a terapia com GHr melhora a altura final. Recentemente, tem-se chamado a atenção para a associação entre GH e câncer. O risco de câncer nessas pacientes está associado à presença de fragmentos do cromossomo Y que pode levar ao desenvolvimento de gonadoblastoma. Dessa forma, a administração de GHr na ST deve ser feita com cautela. A investigação de seqüências do cromossomo Y deve ser realizada, bem como a gonadectomia profilática nos casos positivos, conferindo maior segurança ao tratamento.

Crosstalk between GH/IGF-I axis and steroid hormones (progesterone, 17beta-estradiol) in canine mammary tumours

Growth hormone (GH), insulin-like growth factor I (IGF-I), progesterone (P4) and 17beta-estradiol (17-E2) concentrations have been studied in 84 mammary tumours (44 dysplasias and benign tumours and 40 malignant neoplasias) from 33 female dogs. Thirteen normal mammary glands from 80 healthy female dogs were also analysed as controls. GH concentrations were determined in mammary homogenates by radio-immunoassay. IGF-I, P4 and 17-E2 tissue levels were determined by enzyme-immunoassay (EIA) techniques. The potential correlations between GH/IGF-I concentrations and P4 and 17-E2 mammary tissue levels were investigated. Tissue GH (p<0.01) and IGF-I concentrations (p<0.01) were significantly higher in malignant tumours than in benign neoplasms. Likewise, malignant tumours were the mammary lesions that displayed the highest P4 and 17-E2 tissue levels. Strong correlations between GH/IGF-I (n=84; r=0.436; p<0.001), P4/GH (n=84; r=0.562; p<0.001) and 17-E2/IGF-I (n=84; r=0.638; p<0.001) were observed in tumoral tissue homogenates. Our study provides evidence that P4 might increase autocrine GH production which might directly stimulate local or systemic IGF-I secretion. Additionally, the IGF-I effect might be influenced by local levels of 17-E2. These results suggest that all these hormones and factors might act as local growth factors stimulating the development and/or maintenance of canine mammary tumours in an autocrine/paracrine manner.

Growth hormone treatment in human ageing: benefits and risks

This paper will focus on the rationale of using Growth Hormone (GH) as an anti-ageing therapy in the healthy elderly with age-related decline in the activity of the GH/IGF-I axis, the so called "somatopause". Although the age-related decline in the activity of the GH/IGF-I axis is considered to contribute to age-related changes similar to those observed in Growth Hormone Deficient (GHD) adults, GH/IGF-I deficiency or resistance is also known to result in prolonged life expectancy, at least in animals. These data raise the question whether or not GH deficiency constitutes a beneficial adaptation to ageing and therefore requires no therapy. Moreover, although GH therapy has been shown to exert positive effects in GHD patients, its safety, efficacy and role in healthy elderly individuals is highly controversial. This review provides a comprehensive account of the implications of GH therapy in the ageing subject.

Mammary stem cell number as a determinate of breast cancer risk

The 'cancer stem cell hypothesis' posits that cancers, including breast cancer, arise in tissue stem or progenitor cells. If this is the case, then it follows that the risk for developing breast cancer may be determined in part by the number of breast stem/progenitor cells that can serve as targets for transformation. Stem cell number may be set during critical windows of development, including in utero, adolescence, and pregnancy. The growth hormone/insulin-like growth factor-1 axis may play an important role in regulating breast stem cell number during these developmental windows, suggesting an important link between this signaling pathway and breast cancer risk.

The contribution of growth hormone to mammary neoplasia

While the effects of growth hormone (GH) on longitudinal growth are well established, the observation that GH contributes to neoplastic progression is more recent. Accumulating literature implicates GH-mediated signal transduction in the development and progression of a wide range malignancies including breast cancer. Recently autocrine human GH been demonstrated to be an orthotopically expressed oncogene for the human mammary gland. This review will highlight recent evidence linking GH and mammary carcinoma and discuss GH-antagonism as a potential therapeutic approach for treatment of breast cancer.

IGF-1 activates hEAG K(+) channels through an Akt-dependent signaling pathway in breast cancer cells: role in cell proliferation

Previous work from our laboratory has shown that human ether à go-go (hEAG) K(+) channels are crucial for breast cancer cell proliferation and cell cycle progression. In this study, we investigated the regulation of hEAG channels by an insulin-like growth factor-1 (IGF-1), which is known to stimulate cell proliferation. Acute applications of IGF-1 increased K(+) current-density and hyperpolarized MCF-7 cells. The effects of IGF-1 were inhibited by hEAG inhibitors. Moreover, IGF-1 increased mRNA expression of hEAG in a time-dependent manner in parallel with an enhancement of cell proliferation. The MCF-7 cell proliferation induced by IGF-1 is inhibited pharmacologically by Astemizole or Quinidine or more specifically using siRNA against hEAG channel. Either mitogen-activated protein kinase (MAPK) or phosphatidylinositol 3-kinase (PI3K) are known to mediate IGF-1 cell proliferative signals through the activation of extracellular signal-regulated kinase 1/2 (Erk 1/2) and Akt, respectively. In MCF-7 cells, IGF-1 rapidly stimulated Akt phosphorylation, whereas IGF-1 had little stimulating effect on Erk 1/2 which seems to be constitutively activated. The application of wortmannin was found to block the effects of IGF-1 on K(+) current. Moreover, the inhibition of Akt phosphorylation by the application of wortmannin or by a specific reduction of Akt kinase activity reduced the hEAG mRNA levels. Taken together, our results show, for the first time, that IGF-1 increases both the activity and the expression of hEAG channels through an Akt-dependent pathway. Since a hEAG channel is necessary for cell proliferation, its regulation by IGF-1 may thus play an important role in IGF-1 signaling to promote a mitogenic effect in breast cancer cells.