Mitogenic signaling of insulin-like growth factor I in MCF-7 human breast cancer cells requires phosphatidylinositol 3-kinase and is independent of mitogen-activated protein kinase

Clinico-pathological characteristics of IGFR1 and VEGF-A co-expression in early and locally advanced-stage lung adenocarcinoma

BACKGROUND

Although targeted therapies and immunotherapy have achieved significant clinical benefits in patients with certain pathological types of lung cancer. However, prognosis for patients with lung adenocarcinoma still remains unsatisfactory. It is of extremely importance to find ideal prognostic indicators to predict the prognosis of lung adenocarcinoma patients, especially for patients with early and locally advanced-stage lung adenocarcinoma. The purpose of this study is to elucidate the significance of Insulin-like growth factor receptor 1 (IGFR1) and Vascular endothelial growth factor A (VEGF-A) expression in predicting progression-free survival (PFS) and overall survival (OS) in patients with early and locally advanced-stage lung adenocarcinoma.

METHODS

In this study, IGFR1 and VEGF-A expression on 119 specimens of patients early and locally advanced-stage lung adenocarcinoma were analyzed by immunohistochemistry with an H-score system.

RESULTS

Both high IGFR1 expression and VEGF-A expression patients were resulted in 59 (49.6%) separately. The numbers and proportions of IGFR1-&VEGF-A- subgroup, IGFR1-&VEGF-A+ subgroup, IGFR1+&VEGF-A- subgroup and IGFR1+&VEGF-A+ subgroup are 23 (19.3%), 37 (31.1%), 37 (31.1%) and 22 (18.5%) respectively. High IGFR1 expression was significantly associated with both poor PFS and OS of all patients in a univariate analysis. Multivariable analysis showed that patients with IGFR1+&VEGF-A+ expression exhibited a worst PFS and OS in the subgroup of lung adenocarcinoma patients with EGFR mutation.

CONCLUSIONS

These results suggest that IGFR1+&VEGF-A+ is expected to be a disadvantageous factor for prognosis in the subgroup of EGFR mutation in patients with early and locally advanced-stage lung adenocarcinoma. What's more, this study may provide the theoretical possibility to screen optimal population for a combination therapy with anti-VEGF and anti-IGFR1 in patients with early and locally advanced-stage lung adenocarcinoma.

Aberrant APOBEC3B Expression in Breast Cancer Is Linked to Proliferation and Cell Cycle Phase

APOBEC3B (A3B) is aberrantly overexpressed in a subset of breast cancers, where it associates with advanced disease, poor prognosis, and treatment resistance, yet the causes of A3B dysregulation in breast cancer remain unclear. Here, A3B mRNA and protein expression levels were quantified in different cell lines and breast tumors and related to cell cycle markers using RT-qPCR and multiplex immunofluorescence imaging. The inducibility of A3B expression during the cell cycle was additionally addressed after cell cycle synchronization with multiple methods. First, we found that A3B protein levels within cell lines and tumors are heterogeneous and associate strongly with the proliferation marker Cyclin B1 characteristic of the G2/M phase of the cell cycle. Second, in multiple breast cancer cell lines with high A3B, expression levels were observed to oscillate throughout the cell cycle and again associate with Cyclin B1. Third, induction of A3B expression is potently repressed throughout G0/early G1, likely by RB/E2F pathway effector proteins. Fourth, in cells with low A3B, induction of A3B through the PKC/ncNF-κB pathway occurs predominantly in actively proliferating cells and is largely absent in cells arrested in G0. Altogether, these results support a model in which dysregulated A3B overexpression in breast cancer is the cumulative result of proliferation-associated relief from repression with concomitant pathway activation during the G2/M phase of the cell cycle.

Circular RNAs in Pregnancy and the Placenta

The emerging field of circular RNAs (circRNAs) has identified their novel roles in the development and function of many cancers and inspired the interest of many researchers. circRNAs are also found throughout the healthy body, as well as in other pathological states, but while research into the function and abundance of circRNAs has progressed, our overall understanding of these molecules remains primitive. Importantly, recent studies are elucidating new roles for circRNAs in pregnancy, particularly in the placenta. Given that many of the genes responsible for circRNA production in cancer are also highly expressed in the placenta, it is likely that the same genes act in the production of circRNAs in the placenta. Furthermore, placental development can be referred to as ‘controlled cancer’, as it shares many key signalling pathways and hallmarks with tumour growth and metastasis. Hence, the roles of circRNAs in this field are important to study with respect to pregnancy success but also may provide novel insights for cancer progression. This review illuminates the known roles of circRNAs in pregnancy and the placenta, as well as demonstrating differential placental expressions of circRNAs between complicated and uncomplicated pregnancies.

Prognostic impact of body mass index (BMI) in HER2+ breast cancer treated with anti-HER2 therapies: from preclinical rationale to clinical implications

Human Epidermal growth factor Receptor 2 (HER2) overexpression or HER2 gene amplification defines a subset of breast cancers (BCs) characterized by higher biological and clinical aggressiveness. The introduction of anti-HER2 drugs has remarkably improved clinical outcomes in patients with both early-stage and advanced HER2+ BC. However, some HER2+ BC patients still have unfavorable outcomes despite optimal anti-HER2 therapies. Retrospective clinical analyses indicate that overweight and obesity can negatively affect the prognosis of patients with early-stage HER2+ BC. This association could be mediated by the interplay between overweight/obesity, alterations in systemic glucose and lipid metabolism, increased systemic inflammatory status, and the stimulation of proliferation pathways resulting in the stimulation of HER2+ BC cell growth and resistance to anti-HER2 therapies. By contrast, in the context of advanced disease, a few high-quality studies, which were included in a meta-analysis, showed an association between high body mass index (BMI) and better clinical outcomes, possibly reflecting the negative prognostic role of malnourishment and cachexia in this setting. Of note, overweight and obesity are modifiable factors. Therefore, uncovering their prognostic role in patients with early-stage or advanced HER2+ BC could have clinical relevance in terms of defining subsets of patients requiring more or less aggressive pharmacological treatments, as well as of designing clinical trials to investigate the therapeutic impact of lifestyle interventions aimed at modifying body weight and composition. In this review, we summarize and discuss the available preclinical evidence supporting the role of adiposity in modulating HER2+ BC aggressiveness and resistance to therapies, as well as clinical studies reporting on the prognostic role of BMI in patients with early-stage or advanced HER2+ BC.

Glucocorticoid receptor triggers a reversible drug-tolerant dormancy state with acquired therapeutic vulnerabilities in lung cancer

The glucocorticoid receptor (GR) regulates gene expression, governing aspects of homeostasis, but is also involved in cancer. Pharmacological GR activation is frequently used to alleviate therapy-related side-effects. While prior studies have shown GR activation might also have anti-proliferative action on tumours, the underpinnings of glucocorticoid action and its direct effectors in non-lymphoid solid cancers remain elusive. Here, we study the mechanisms of glucocorticoid response, focusing on lung cancer. We show that GR activation induces reversible cancer cell dormancy characterised by anticancer drug tolerance, and activation of growth factor survival signalling accompanied by vulnerability to inhibitors. GR-induced dormancy is dependent on a single GR-target gene, CDKN1C, regulated through chromatin looping of a GR-occupied upstream distal enhancer in a SWI/SNF-dependent fashion. These insights illustrate the importance of GR signalling in non-lymphoid solid cancer biology, particularly in lung cancer, and warrant caution for use of glucocorticoids in treatment of anticancer therapy related side-effects.

The Clinical Significance of IGF-1R and Relationship with Epstein-Barr Virus Markers: LMP1 and EBERs in Tunisian Patients with Nasopharyngeal Carcinoma

OBJECTIVES

Tunisia is in the endemic area of nasopharyngeal carcinoma. Epstein-Barr virus (EBV) based assays have been commonly used as standard markers for screening and monitoring the disease. So, it is very important to find novel factors for the early diagnostic and prognostic evaluation of this cancer. The aim of the study was to evaluate the expression of IGF-1R (Insulin Growth Factor Receptor 1), LMP 1 (Latent Membrane Protein 1) and EBERs (EBV encoded RNAs) in order to determine their correlation with clinicopathologic parameters and survival rates in patients with nasopharyngeal carcinoma (NPC). We also looked for the relationship between these biomarkers.

METHODS

IGF-1R and LMP1 expression was performed by means of immunohistochemical method and EBERs were detected using in situ hybridization of paraffin embedded tumor tissues of 94 patients with nasopharyngeal carcinoma and 45 non-cancerous nasopharyngeal mucosa samples.

RESULTS

Our findings demonstrated that IGF-1R was over expressed in 47.87% of NPC patients and only in 2.22% of controls. Positive LMP1 expression was detected in 56.38% of NPC patients and all NPC patients were positive for the EBV-encoded RNAs staining. A statistically significant positive correlation was observed between IGF-1R expression and the tumor size (P < .001). Kaplan-Meier survival curves showed that NPC patients with a strong IGF-1R expression level have shorter median and 5-year Overall Survival than those with weak expression rates (100.15 vs 102.68 months, P = .08). In addition, median and 5-year Disease-Free Survival was significantly lower in the LMP1 positive NPC patients than in the LMP1 negative ones (53.38 vs 93.37 months, P = .03). Moreover, LMP1 expression correlated strongly with IGF-1R expression (P = .018). The relationship between these two biomarkers could influence patient survival.

CONCLUSION

IGF1-R and LMP1 could be valuable prognostic markers in Tunisian NPC patients.

IGF-1 and hyperglycaemia-induced FOXA1 and IGFBP-2 affect epithelial to mesenchymal transition in prostate epithelial cells

Localized prostate cancer (PCa) is a manageable disease but for most men with metastatic disease, it is often fatal. A western diet has been linked with PCa progression and hyperglycaemia has been associated with the risk of lethal and fatal prostate cancer. Using PCa cell lines, we examined the impact of IGF-I and glucose on markers of epithelial-to-mesenchymal transition (EMT), migration and invasion. We examined the underlying mechanisms using cell lines and tumour tissue samples. IGF-I had differential effects on the process of EMT: inhibiting in normal and promoting in cancer cells, whereas hyperglycamia alone had a stimulatory effect in both. These effects were independent of IGF and in both cases, hyperglycaemia induced an increase IGFBP-2(tumour promoter) and FOXA1. A positive correlation existed between levels of IGFBP-2 and FOXA1 in benign and cancerous prostate tissue samples and in vitro and in vivo data indicated that FOXA1 strongly interacted with the IGFBP-2 gene in normal prostate epithelial cells that was associated with a negative regulation of IGFBP-2, whereas in cancer cells the level of FOXA1 associating with the IGFBP-2 gene was minimal, suggesting loss of this negative regulation. IGF-I and hyperglycaemia-induced FOXA1/IGFBP-2 play important roles in EMT.

Cartilage-Targeted IGF-1 Treatment to Promote Longitudinal Bone Growth

Recombinant human growth hormone (GH) is commonly used to treat short stature in children. However, GH treatment has limited efficacy, particularly in severe, non-GH-deficient conditions such as chondrodysplasias, and potential off-target effects. Because short stature results from decreased growth plate chondrogenesis, we developed a cartilage-targeting single-chain human antibody fragment (CaAb) aiming to deliver therapeutic molecules to the growth plate, thereby increasing treatment efficacy while minimizing adverse effects on other tissues. To this end, we created fusion proteins of these CaAbs conjugated with insulin-like growth factor 1 (IGF-1), an endocrine and/or paracrine factor that positively regulates chondrogenesis. These CaAb-IGF-1 fusion proteins retained both cartilage binding and IGF-1 biological activity, and they were able to stimulate bone growth in an organ culture system. Using a GH-deficient (lit) mouse model, we found that subcutaneous injections of these CaAb-IGF-1 fusion proteins increased overall growth plate height without increasing proliferation in kidney cortical cells, suggesting on-target efficacy at the growth plate and less off-target effect on the kidney than IGF-1 alone. Alternate-day injections of these fusion proteins, unlike IGF-1 alone, were sufficient to produce a therapeutic effect. Our findings provide proof of principle that targeting therapeutics to growth plate cartilage can potentially improve treatment for childhood growth disorders.

Metformin increases antitumor activity of MEK inhibitor binimetinib in 2D and 3D models of human metastatic melanoma cells

Melanoma is one of the most aggressive and treatment-resistant tumors that responsible for majority of skin-cancer related deaths. Here we propose a combination of MEK inhibitor binimetinib with metformin as a promising therapy against human melanoma cells in vitro, including BRAF -mutated A375, Mel Z, and Mel IL cells, and NRAS-mutated Mel MTP and Mel Me cells. Additionally, we obtained two close to clinical practice models of melanoma progression. The first one was vemurafenib-resistant Mel IL/R melanoma cells with acquired resistance to BRAF inhibition-targeted therapy, and the second one was tumor spheroids, which are 3D in vitro model of small-size solid tumors in vivo. The cytotoxicity of binimetinib and metformin was synergistic in both 2D and 3D melanoma culture and mediated through apoptotic pathway. The combination reduced the number of melanoma-formed colonies, inhibited cell invasion and migration, and led to G0/G1 cell cycle arrest through cyclin D/CDK4/CDK6 pathway. The mechanism of metformin and binimetinib synergy in melanoma cells was associated with increased activation of p-AMPKα and decreased p-ERK, but not with alterations in p-mTOR. In summary, the combination of metformin and binimetinib resulted in stronger anti-proliferative effects on melanoma cells compared to binimetinib alone, and therefore could be promising for clinical applications.

The β-glucan from Lentinus edodes suppresses cell proliferation and promotes apoptosis in estrogen receptor positive breast cancers

Breast cancer is now the most common cancer in worldwide women, and novel interventions are needed to overcome the resistance occurring in the estrogen-targeted endocrine therapy. Herein, we demonstrate that the β-glucan from Lentinus edodes (LNT) exhibited a profound inhibition ratio of ∼53% against estrogen receptor positive (ER+) MCF-7 tumor growth in nude mice similar to the positive control of cisplatin. Immunohistochemistry images showed that LNT evidently suppressed cell proliferation and promoted apoptosis in MCF-7 tumor tissues. The Western blotting analysis indicated that LNT up-regulated the tumor suppressor p53, phosphorylated extracellular signal-regulated kinase1/2 (p-ERK1/2), cleaved-Caspase 3 and poly [ADP (ribose)] polymerase 1 (PARP 1) protein levels, and reduced the expression of mouse double minute 2 (MDM2), telomerase reverse transcriptase (TERT), nuclear factor-kappa B (NF-κB) p65, B-cell lymphoma-2 (Bcl-2), estrogen receptor α (ERα), etc. in tumor tissues. Moreover, LNT significantly suppressed phosphatidylinositol 3-kinase (PI3K), phosphorylated protein kinase B (p-Akt) and mammalian target of rapamycin (mTOR) protein levels. It was thus proposed that LNT inhibited MCF-7 tumor growth through suppressing cell proliferation and enhancing apoptosis possibly via multiple pathways such as PI3K/Akt/mTOR, NF-κB-, ERK-, ERα-, caspase- and p53-dependent pathways. Interestingly, the cell viability assay, siRNA transfection, Western blotting and flow cytometric analysis suggested that LNT targeted p53/ERα to only suppress cell proliferation via cell cycle arrest at G2/M phase without apoptosis in vitro. The big difference between in vivo and in vitro data suggested that the immune responses triggered by the polysaccharide should mainly contribute to the apoptotic effect in vivo. Overall, this work provides a novel strategy to treat ER+ breast cancers by using a naturally occurring β-glucan from mushrooms.

Insulin-Like Growth Factor I Receptor (IGF-IR) Ligands and BMI in Squamous Intra-Epithelial Lesion (SIL) of Cervix

INTRODUCTION

Cancer cervix is the most common cancer in women in developing countries like India. Several studies have linked insulin-like growth factors-I & II (IGF-I and IGF-II) and IGF binding proteins-3 (IGFBP-3) with pathogenesis of Squamous Intraepithelial Lesion of cervix (SIL). To the best of our knowledge, no study has shown any correlation between circulating C-Peptide levels and SIL.

AIM

The present study has attempted to evaluate the correlation between SIL and IGF-IR ligands (IGF-I, IGF-II, C-Peptide), IGF binding protein (IGFBP-3) and Body Mass Index (BMI).

MATERIALS AND METHODS

The present case-control study consisted of 31 histologically proven SIL cases and 31 age matched controls without evidence of SIL. A 10 ml blood sample was collected in heparinized vial. Plasma was separated immediately using centrifugation and was stored at -80(0) C till further analysis. Plasma levels of IGF-I, IGF-II, C-peptide and IGFBP3 were measured using commercially available Enzyme Linked Immunosorbent Assay (ELISA) kit. Height and weight was noted for calculation of BMI. Bio-effective molar ratio (BEMR) was calculated as 3.72 x {(0.25 x IGF-I) + (0.032 x IGF-II) + (0.0025 x C-peptide)} / {(1435 + IGFBP-3) - (2.79 x IGF-I) - (2.87 x IGF-II)}. Statistical analysis was performed using SPSS and Microsoft Excel software employing student t-test, Mann-Whitney and Chi-square test for trend while binary logistic regression was used to estimate the odds ratios (OR) and corresponding 95% Confidence Intervals (CI).

RESULT

IGF-I, IGF-II levels and BEMR were significantly increased in SIL compared to controls (p= 0.001, p <0.001, and p <0.001, respectively). C-Peptide levels were higher in controls than SIL (p = 0.04). IGFBP-3 & BMI in SIL were not significantly related when compared with controls. Risk of SIL in 4(th) quartile for BEMR, IGF-I, and IGF-II was 12.18(95% CI= 3.13-47.39), 3.94(95% CI = 1.24-12.56), and 4.57(95% CI = 1.42-14.7), respectively.

CONCLUSION

Elevated levels of IGF-I and IGF-II are associated with risk of SIL while BEMR emerges out to be a derived factor strongly associated with risk of SIL.

Six1 induces protein synthesis signaling expression in duck myoblasts mainly via up-regulation of mTOR

As a critical transcription factor, Six1 plays an important role in the regulation of myogenesis and muscle development. However, little is known about its regulatory mechanism associated with muscular protein synthesis. The objective of this study was to investigate the effects of overexpression ofSix1 on the expression of key protein metabolism-related genes in duck myoblasts. Through an experimental model where duck myoblasts were transfected with a pEGFP-duSix1 construct, we found that overexpression of duckSix1 could enhance cell proliferation activity and increase mRNA expression levels of key genes involved in the PI3K/Akt/mTOR signaling pathway, while the expression of FOXO1, MuRF1and MAFbx was not significantly altered, indicating thatSix1 could promote protein synthesis in myoblasts through up-regulating the expression of several related genes. Additionally, in duck myoblasts treated with LY294002 and rapamycin, the specific inhibitors ofPI3K and mTOR, respectively, the overexpression of Six1 could significantly ameliorate inhibitive effects of these inhibitors on protein synthesis. Especially, the mRNA expression levels of mTOR and S6K1 were observed to undergo a visible change, and a significant increase in protein expression of S6K1 was seen. These data suggested that Six1plays an important role in protein synthesis, which may be mainly due to activation of the mTOR signaling pathway.

Reduced expression of EI24 confers resistance to gefitinib through IGF-1R signaling in PC9 NSCLC cells

OBJECTIVES

Lung cancer is the commonly diagnosed cancer and is the leading cause of cancer-related mortality worldwide. The most prevalent form of lung cancer is NSCLC, comprising 80% of all lung cancer cases, and epidermal growth factor receptor (EGFR) is frequently mutated in NSCLC. EI24 is a p53-responsive gene and plays an important role in tumor suppression. In the current study, we found that reduced expression of EI24 conferred resistance to EGFR-tyrosine-kinase inhibitor (TKI) in NSCLC cells.

MATERIALS AND METHODS

The correlation between EI24 expression and EGFR-TKI drug resistance in EGFR-driven tumors were determined from microarray datasets. The phospho-protein expression profiles of receptor tyrosine kinases and protein kinases were examined using antibody arrays method in PC9 cells expressing shRNAs targeting EI24 and gefitinib-resistant PC9-GR cells expressing exogenous EI24.

RESULTS AND CONCLUSIONS

The EGFR-TKI resistant clones had reduced expression of EI24 mRNA compared to the sensitive clones, and EI24 knockdown rendered sensitive cells resistant to EGFR-TKI. Receptor tyrosine kinase screening revealed the involvement of a kinase switch in EI24-mediated regulation of drug sensitivity. We found that EI24 modulates the insulin growth factor-1 receptor (IGF-1R) pathway through the induction of IGF-1. Combination treatment with EGFR and IGF-1R inhibitors significantly reduced the viability of EI24 knockdown-induced resistant cell lines compared to single-agent treatments. We also showed that low EI24 and high IGF-1R expressions in lung cancer patients were correlated with reduced overall survival. Taken together, these results suggest a potential role for EI24 as a biomarker of drug resistance, and indicate that combination therapy with EGFR and IGF-1R inhibitors would be effective in NSCLC patients with low EI24 expression.

Suppressive effect of membrane-permeable peptides derived from autophosphorylation sites of the IGF-1 receptor on breast cancer cells

Insulin-like growth factor-1 (IGF-1) receptors play a crucial role in the biology of human cancer, making them an attractive target for anti-cancer agents. We previously designed oligopeptides containing the amino-acid sequences surrounding the autophosphorylation sites of the insulin receptor and found that two of them, namely, Ac-DIYET-NH2 and Ac-DYYRK-NH2, suppressed phosphorylation of purified insulin receptors in a non-ATP-competitive manner, whereas Ac-NIYQT-NH2 and Ac-NYYRK-NH2 suppressed in an ATP-competitive manner. Because the IGF-1 receptor is closely related to the insulin receptor, the aim of this study was to observe the effects of these peptides, which correspond to the amino-acid sequences of the autophosphorylation sites of the IGF-1 receptor, on the activity of the human breast cancer cell lines MCF-7, T47D, MDA-MB-231, and MDA-MB-453. To facilitate peptide delivery into breast cancer cells, the cell-penetrating peptide, human immunodeficiency virus type 1-transactivator of transcription (Tat), was linked to these peptides. When breast cancer cells were treated with each of these synthetic Tat-conjugated peptides, the conjugated peptides penetrated into the cells and suppressed cell proliferation. An inhibitory effect of Tat-conjugated peptides against IGF-1-stimulated phosphorylation of IGF-1 receptors was observed. In addition, we found that combinations of these peptides suppressed phosphorylation of IGF-1 receptors to a greater extent than the peptides did individually. In conclusion, IGF-1 receptor autophosphorylation site-derived membrane-permeable peptides have the potential to suppress IGF-1 receptor function in breast cancer cells and to be developed into novel and useful agents for cancer therapy.

Insulin-like growth factor and epidermal growth factor signaling in breast cancer cell growth: focus on endocrine resistant disease

Breast cancer is the most common type of cancer for women worldwide with a lifetime risk amounting to a staggering total of 10%. It is well established that the endogenous synthesis of insulin-like growth factor (IGF) and epidermal growth factor (EGF) polypeptide growth factors are closely correlated to malignant transformation and all the steps of the breast cancer metastatic cascade. Numerous studies have demonstrated that both estrogens and growth factors stimulate the proliferation of steroid-dependent tumor cells, and that the interaction between these signaling pathways occurs at several levels. Importantly, the majority of breast cancer cases are estrogen receptor- (ER-) positive which have a more favorable prognosis and pattern of recurrence with endocrine therapy being the backbone of treatment. Unfortunately, the majority of patients progress to endocrine therapy resistant disease (acquired resistance) whereas a proportion of patients may fail to respond to initial therapy (de novo resistance). The IGF-I and EGF downstream signaling pathways are closely involved in the process of progression to therapy resistant disease. Modifications in the bioavailability of these growth factors contribute critically to disease progression. In the present review therefore, we will discuss in depth how IGF and EGF signaling participate in breast cancer pathogenesis and progression to endocrine resistant disease.

Crosstalk with insulin and dependence on PI3K/Akt/mTOR rather than MAPK pathways in upregulation of basal growth following long-term oestrogen deprivation in three human breast cancer cell lines

BACKGROUND

MCF-7, T-47-D, ZR-75-1 human breast cancer cell lines are dependent on oestrogen for growth but can adapt to grow during long-term oestrogen deprivation. This serves as a model for identification of therapeutic targets in endocrine-resistant breast cancer.

METHODS

An overlooked complication of this model is that it involves more than non-addition of oestrogen, and inadequate attention has been given to separating molecular events associated with each of the culture manipulations.

RESULTS

Insulin and oestradiol were shown to protect MCF-7 cells against upregulation of basal growth, demonstrating a crosstalk in the growth adaptation process. Increased phosphorylation of p44/42MAPK and c-Raf reflected removal of insulin from the medium and proliferation of all three cell lines was inhibited to a lesser extent by PD98059 and U0126 following long-term oestrogen/insulin withdrawal, demonstrating a reduced dependence on the MAPK pathway. By contrast, long-term oestrogen/insulin deprivation did not alter levels of phosphorylated Akt and did not alter the dose-response of growth inhibition with LY294002 in any of the three cell lines. The IGF1R inhibitor picropodophyllin inhibited growth of all MCF-7 cells but only in the long-term oestrogen/insulin-deprived cells was this paralleled by reduction in phosphorylated p70S6K, a downstream target of mTOR. Long-term oestrogen/insulin-deprived MCF-7 cells had higher levels of phosphorylated p70S6K and developed increased sensitivity to growth inhibition by rapamycin.

CONCLUSIONS

The greater sensitivity to growth inhibition by rapamycin in all three cell lines following long-term oestrogen/insulin deprivation suggests rapamycin-based therapies might be more effective in breast cancers with acquired oestrogen resistance.

Estrogen receptor-α36 is involved in pterostilbene-induced apoptosis and anti-proliferation in in vitro and in vivo breast cancer

Pterostilbene (trans-3,5-dimethoxy-4′-hudroxystilbene) is an antioxidant primarily found in blueberries. It also inhibits breast cancer regardless of conventional estrogen receptor (ER-α66) status by inducing both caspase-dependent and caspase-independent apoptosis. However, the pterostilbene-induced apoptosis rate in ER-α66-negative breast cancer cells is much higher than that in ER-α66-positive breast cancer cells. ER-α36, a variant of ER-α66, is widely expressed in ER-α66-negative breast cancer, and its high expression mediates the resistance of ER-α66-positive breast cancer patients to tamoxifen therapy. The aim of the present study is to determine the relationship between the antiproliferation activity of pterostilbene and ER-α36 expression in breast cancer cells. Methyl-thiazolyl-tetrazolium (MTT) assay, apoptosis analysis, and an orthotropic xenograft mouse model were used to examine the effects of pterostilbene on breast cancer cells. The expressions of ER-α36 and caspase 3, the activation of ERK and Akt were also studied through RT-PCR, western blot analysis, and immunohistochemical (IHC) staining. ER-α36 knockdown was found to desensitize ER-α66-negative breast cancer cells to pterostilbene treatment both in vitro and in vivo, and high ER-α36 expression promotes pterostilbene-induced apoptosis in breast cancer cells. Western blot analysis data indicate that MAPK/ERK and PI3K/Akt signaling in breast cancer cells with high ER-α36 expression are mediated by ER-α36, and are inhibited by pterostilbene. These results suggest that ER-α36 is a therapeutic target in ER-α36-positive breast cancer, and pterostilbene is an inhibitor that targets ER-α36 in the personalized therapy against ER-α36-positive breast cancer.

Function of RasGRP3 in the formation and progression of human breast cancer

Introduction

Ras guanine nucleotide exchange factors (RasGEFs) mediate the activation of the Ras signaling pathway that is over activated in many human cancers. The RasGRP3, an activator of H-Ras and R-Ras protein exerts oncogenic effects and the overexpression of the protein is observed in numerous malignant cancer types. Here, we investigated the putative alteration of expression and potential function of RasGRP3 in the formation and progression of human breast cancer.

Methods

The RasGRP3 and phosphoRasGRP3 expressions were examined in human invasive ductal adenocarcinoma derived samples and cell lines (BT-474, JIMT-1, MCF7, SK-BR-3, MDA-MB-453, T-47D) both in mRNA (Q-PCR) and protein (Western blot; immunohistochemistry) levels. To explore the biological function of the protein, RasGRP3 knockdown cultures were established. To assess the role of RasGRP3 in the viability of cells, annexin-V/PI staining and MitoProbe™ DilC1 (5) assay were performed. To clarify the function of the protein in cell proliferation and in the development of chemotherapeutic resistance, CyQuant assay was performed. To observe the RasGRP3 function in tumor formation, the Severe combined immunodeficiency (SCID) mouse model was used. To investigate the role of the protein in Ras-related signaling Q-PCR and Western blot experiments were performed.

Results

RasGRP3 expression was elevated in human breast tumor tissue samples as well as in multiple human breast cancer cell lines. Down-regulation of RasGRP3 expression in breast cancer cells decreased cell proliferation, induced apoptosis in MCF7 cells, and sensitized T-47D cells to the action of drugs Tamoxifen and trastuzumab (Herceptin). Gene silencing of RasGRP3 reduced tumor formation in mouse xenografts as well. Inhibition of RasGRP3 expression also reduced Akt, ERK1/2 and estrogen receptor alpha phosphorylation downstream from IGF-I insulin like growth factor-I (IGF-I) or epidermal growth factor (EGF) stimulation confirming the functional role of RasGRP3 in the altered behavior of these cells.

Conclusions

Taken together, our results suggest that the Ras activator RasGRP3 may have a role in the pathological behavior of breast cancer cells and may constitute a therapeutic target for human breast cancer.

The therapeutic target of estrogen receptor-alpha36 in estrogen-dependent tumors

Estrogen receptor-alpha36 (ER-α36) is a new isoform of estrogen receptors without transcriptional activation domains of the classical ER-α(ER - α66). ER-α36 is mainly located in cytoplasm and plasma membrane. ER-α36 mediates non-genomic signaling and is involved in genomic signaling of other ERs. Recently ER-α36 is found to play a critical role in the development of estrogen-dependent cancers and endocrine resistance of breast cancer. The present article overviews and updates the biological nature and function of ER-α36, potential interaction of ER-α36 with other estrogen receptors and growth factor receptors, intracellular signaling pathways, potential mechanism by which ER-α36 may play an important role in the development of tumor resistance to endocrine therapies.

PIK3CA gene amplification and PI3K p110α protein expression in breast carcinoma

A family of PI3Ks is the lipid kinases, which enhance intracellular pools of phosphatidyl inositol 3,4,5-tri-phosphate (PIP3) through phosphorylating its precursor. Amplifications and deletions of genes, as well as somatic missense of the PIK3CA gene have been described in many human cancer varieties, including of the brain, colon, liver, lung and stomach. Immunohistochemistry and Real-time quantitative PCR tests were used to determine the PIK3CA gene amplification (gene copy number) and to detect protein expression, respectively. The results obtained were analysed and the ratio of PIK3CA to β-actin gene copy number was calculated. Positive gene amplification of PIK3CA was appointed as a copy number of ≥4. Also, PI3K p110α protein expression was scored from 0 to 3+ and the scores of 2+ and 3+ were considered as positive for PI3K p110α protein expression. We studied 50 breast carcinoma samples for PI3K p110α protein expression and PIK3CA gene copy numbers. In general, 36 out of 50 (72%) breast carcinoma samples showed a significant increase in PIK3CA gene amplification. 12 out of 50 (24%) showed positive staining, and 38 out of 50 (76%) showed negative staining for PI3K p110α expression. We have identified no significant relationship between PIK3CA amplification, race (p= 0.630) and histological type (p=0. 731) in breast carcinoma, but correlation of PIK3CA amplification and age showed a significant relationship (p=0. 003) between them. No significant relationship has been identified in correlation of PI3K p110α protein expression compared to age (p=0. 284), race (p=0. 546) and histological type (p=0. 285). Amplification of PIK3CA was frequent in breast carcinoma and occurs in stages of breast carcinoma. Our result shows that there is a relationship between gene amplification and age in breast carcinoma. We suggest that PIK3CA is significant in breast tumorigenesis serve as a prevalent mechanism contributes to the oncogenic activation pathway of PIK3CA in breast cancer.

Insulin like growth factor 2 regulation of aryl hydrocarbon receptor in MCF-7 breast cancer cells

Insulin like growth factor (IGF)-1 and IGF-2 stimulate normal growth, development and breast cancer cell proliferation. Cyclin D1 (CCND1) promotes cell cycle by inhibiting retinoblastoma protein (RB1). The aryl hydrocarbon receptor (AHR) is a major xenobiotic receptor that also regulates cell cycle. The purpose of this study was to investigate whether IGF-2 promotes MCF-7 breast cancer proliferation by inducing AHR. Western blot and quantitative real time PCR (Q-PCR) analysis revealed that IGF-2 induced an approximately 2-fold increase (P<.001) in the expression of AHR and CCND1. Chromatin immunoprecipitation (ChIP), followed by Q-PCR indicated that IGF-2 promoted (P<.001) a 7-fold increase in AHR binding on the CCND1 promoter. AHR knockdown significantly (P<.001) inhibited IGF-2 stimulated increases in CCND1 mRNA and protein. AHR knockdown cells were less (P<.001) responsive to the proliferative effects of IGF-2 than control cells. Collectively, our findings have revealed a new regulatory mechanism by which IGF-2 induction of AHR promotes the expression of CCND1 and the proliferation of MCF-7 cells. This previously uncharacterized pathway could be important for the proliferation of IGF responsive cancer cells that also express AHR.

Insulin and IGFs in obesity-related breast cancer

Obesity and the Metabolic Syndrome are associated with multiple factors that may cause an increased risk for cancer and cancer-related mortality. Factors involved include hyperinsulinemia, hyperglycemia, hyperlipidemia and IGFs. Insulin resistance is also associated with alterations in the levels of proinflammatory cytokines, chemokines, adipokines (leptin, adiponectin) that may also be contributing factors. The insulin family of proteins is ubiquitously expressed and has pleiotropic effects on metabolism and growth. However insulin, IGF-1 and particularly IGF-2 have been identified as tumor promoters in multiple studies. Mouse models have focused on insulin and IGF-1 and their receptors as being involved in tumor progression and metastases. The role of the insulin receptor as either mediating the effects on tumors or as compensating for the insulin-like growth factor receptor has arisen. Its role has been supported by preclinical studies and the importance of insulin resistance and hyperinsulinemia in obesity and early diabetes. Since the focus of this review is the insulin-family we will focus on insulin, IGF-1 and IGF-2.

MicroRNA signature in metastatic colorectal cancer patients treated with anti-EGFR monoclonal antibodies

BACKGROUND

To investigate whether microRNAs are predictive of sensitivity to anti-epidermal growth factor receptor (EGFR) monoclonal antibodies in patients with metastatic colorectal cancer (mCRC).

METHODS

A total of 183 mCRC cases from 2 independent cohorts (cohort 1: 74 cases; validation cohort: 109 cases) treated with cetuximab or panitumumab were included in the study. MiRNA arrays were analyzed using Agilent's miRNA platform.

RESULTS

The study identified the cluster Let-7c/miR-99a/miR-125b as a signature associated with an outcome different from that of anti-EGFR therapies. In the first cohort, patients with high-intensity signatures had a significantly longer progression-free survival (PFS) (6.1 vs. 2.3 mo; P = .02) and longer overall survival (OS) ( 29.8 vs. 7.0 mo, P = .08) than patients with low-intensity signatures. In the validation cohort, patients with high signature had significantly longer PFS and OS than individuals with low-intensity signatures (PFS 7.8 vs. 4.3 mo, P = .02; OS 12.8 vs. 7.5 mo, P = .02). In the KRAS wild-type population (n = 120), high-intensity signature patients had a significantly longer PFS (7.8 vs. 4.6 mo, P = .016) and longer OS (16.1 vs. 10.9 mo, P = .09) than low-signature individuals, with no difference in KRAS mutated patients.

CONCLUSION

The MiR-99a/Let-7c/miR-125b signature may improve the selection of patients with KRAS wild-type mCRC as good candidates for anti-EGFR therapy.

K(+) channels and cell cycle progression in tumor cells

K⁺ ions play a major role in many cellular processes. The deregulation of K⁺ signaling is associated with a variety of diseases such as hypertension, atherosclerosis, or diabetes. K⁺ ions are important for setting the membrane potential, the driving force for Ca²⁺ influx, and regulate volume of growing cells. Moreover, it is increasingly recognized that K⁺ channels control cell proliferation through a novel signaling mechanisms triggered and modulated independently of ion fluxes. In cancer, aberrant expression, regulation and/or sublocalization of K⁺ channels can alter the downstream signals that converge on the cell cycle machinery. Various K⁺ channels are involved in cell cycle progression and are needed only at particular stages of the cell cycle. Consistent with this idea, the expression of Eag1 and HERG channels fluctuate along the cell cycle. Despite of acquired knowledge, our understanding of K⁺ channels functioning in cancer cells requires further studies. These include identifying the molecular mechanisms controlling the cell cycle machinery. By understanding how K⁺ channels regulate cell cycle progression in cancer cells, we will gain insights into how cancer cells subvert the need for K⁺ signal and its downstream targets to proliferate.

Phosphatidylinositol 3-kinases inhibitor LY294002 potentiates the cytotoxic effects of doxorubicin, vincristine, and etoposide in a panel of cancer cell lines

Many novel therapeutic approaches to overcome chemoresistance have involved targeting specific signaling pathways such as the phosphatidylinositol 3-kinase (PI3K) pathway. PI3K is a known stress response pathway which is involved in the regulation of cell survival, apoptosis, and growth. Inhibition of this pathway may possibly restore or augment the effectiveness of chemotherapy. Using three human malignant cell lines, we examined the effects of LY294002 (PI3K inhibitor) on chemotherapeutic agent-induced apoptosis and cytotoxicity. An antimicrotubule agent vincristine, a topoisomerase II inhibitor etoposide, and a DNA cross-linking agent doxorubicin were used accompanied with LY294002. Cell viability was determined by MTT assay, and the induction of apoptosis was assessed by immunoblotting of caspase-3. Blocking the PI3K/Akt cascade with a PI3K inhibitor LY294002 (10 μM) increased the cytotoxic effect of vincristine and doxorubicin on SK-OV-3 cell line. Furthermore, LY294002 showed a greater promoting effect in etoposide- and doxorubicin-induced cytotoxicity on MDA-MB-468 and A549 cells. The quantity of cleaved caspase-3 in cancer cells that had combination therapy was increased compared with that in the cells treated with each drug alone. We suggest that inhibitors of the PI3K/Akt pathway in combination with chemotherapeutic agents may induce cell death effectively and be a potent modality to treat various types of cancer. The effectiveness of such combination therapy is depending to the used cell line and class of anticancer drug.

Resveratrol regulates the cell viability promoted by 17β-estradiol or bisphenol A via down-regulation of the cross-talk between estrogen receptor α and insulin growth factor-1 receptor in BG-1 ovarian cancer cells

Endocrine disrupting chemicals (EDCs) and estrogens appear to promote development of estrogen-dependent cancers, including breast and ovarian carcinomas. In this study, we evaluated the cell viability effect of BPA on BG-1 human ovarian cancer cells, along with the growth inhibitory effect of resveratrol (trans-3,4,5-trihydroxystilbene; RES), a naturally occurring phytoestrogen. In addition, we investigated the underlying mechanism(s) of BPA and RES in regulating the interaction between estrogen receptor alpha (ERα) and insulin-like growth factor-1 receptor (IGF-1R) signals, a non- genomic pathway induced by 17β-estradiol (E2). BPA induced a significant increase in BG-1 cell growth and up-regulated mRNA levels of ERα and IGF-1R. In parallel with its mRNA level, the protein expression of ERα was induced, and phosphorylated insulin receptor substrate-1 (p-IRS-1), phosphorylated Akt1/2/3, and cyclin D1 were increased by BPA or E2. However, RES effectively reversed the BG-1 cell proliferation induced by E2 or BPA by inversely down-regulating the expressions of ERα, IGF-1R, p-IRS-1, and p-Akt1/2/3, and cyclin D1 at both transcriptional and translational levels. Taken together, these results suggest that RES is a novel candidate for prevention of tumor progression caused by EDCs, including BPA via effective inhibition of the cross-talk of ERα and IGF-1R signaling pathways.

miR-223 functions as a potent tumor suppressor of the Lewis lung carcinoma cell line by targeting insulin-like growth factor-1 receptor and cyclin-dependent kinase 2

microRNAs (miRNAs) have been hypothesized to function as oncogenes or tumor suppressors by targeting specific cancer-related genes. Previous studies have reported that miR-223 may serve as a tumor suppressor in a number of cancer types, however, knowledge of its targets in non-small cell lung cancer (NSCLC) remains limited. In the current study, miR-223 was found to inhibit cell proliferation in vitro by CCK-8 assay, growth curves and an anchorage-independent growth assay in a Lewis lung carcinoma (LLC) cell line. miR-223 transfection in the LLC cells was observed to significantly inhibit migration and invasion, induce G₂/M arrest and decrease the expression levels of Sca-1, a marker of murine stem cells. In addition, miR-223 transfection markedly suppressed AKT and ERK signaling, as well as insulin-like growth factor-1 receptor (IGF-1R)-mediated downstream signaling, pathways that are crucial for cell proliferation and invasion in NSCLC cells. Analyses in C57BL/6 mice demonstrated that miR-223 suppresses tumorigenicity in vivo. Using a luciferase activity assay and western blot analysis, IGF-1R and cyclin-dependent kinase 2 (CDK2) were identified as direct targets of miR-223. In the present study, novel cancer-related targets of miR-223 were identified and verified in a LLC cell line, indicating that miR-223 functions as a tumor suppressor, which may fine-tune the activity of the IGF-1R pathway in lung cancer. Therefore, increasing miR-223 expression may provide a novel approach for the treatment of NSCLC.

Interaction between IGF-IR and ER induced by E2 and IGF-I

Estrogen receptor (ER) is a nuclear receptor and the insulin-like growth factor-I (IGF-I) receptor (IGF-IR) is a transmembrane tyrosine kinase receptor. Estrogen and IGF-I are known to have synergistic effects on the growth of breast cancer cells. Recently, non-nuclear effects of ER have been under investigation. To study the mechanism involved in this process, we have used MCF-7 breast cancer cell lines transfected with IGF-IR anti-sense cDNA (SX13, MCF-7(SX13)) that resulted in 50% reduction of IGF-IR. In MCF-7 cells, estradiol (E2) and IGF-I induced the rapid association of ER to IGF-IR, however, the interaction was abrogated in MCF-7(SX13) cells. In addition, NWTB3 cells (NIH3T3 cells overexpressing IGF-IR) were transiently transfected with ERα, the ER-IGF-IR interaction was induced by both E2 and IGF-I. Moreover, ERα regulated the IGF-I signaling pathways through phosphorylation of ERK1/2 and Akt and the interaction of ER-IGF-IR potentiated the cell growth. Finally, E2 and IGF-I stimulated translocation of ER from the nucleus to the cytoplasm. Taken together, these findings reveal that the interaction of the ER and IGF-IR is important for the non-genomic effects of ER.

Arachidonic acid enhances TPA-induced differentiation in human leukemia HL-60 cells via reactive oxygen species-dependent ERK activation

The phorbol ester, 12-O-tetradecanoylphorbol-13-acetate (TPA), is a potent stimulator of differentiation in human leukemia cells; however, the effects of arachidonic acid (AA) on TPA-induced differentiation are still unclear. In the present study, we investigated the contribution of AA to TPA-induced differentiation of human leukemia HL-60 cells. We found that treatment of HL-60 cells with TPA resulted in increases in cell attachment and nitroblue tetrazolium (NBT)-positive cells, which were significantly enhanced by the addition of AA. Stimulation of TPA-induced intracellular reactive oxygen species (ROS) production by AA was detected in HL-60 cells via a DCHF-DA analysis, and the addition of the antioxidant, N-acetyl-cysteine (NAC), was able to reduce TPA+AA-induced differentiation in accordance with suppression of intracellular peroxide elevation by TPA+AA. Furthermore, activation of extracellular-regulated kinase (ERK) and c-Jun N-terminal kinase (JNK) by TPA+AA was identified in HL-60 cells, and the ERK inhibitor, PD98059, but not the JNK inhibitor, SP600125, inhibited TPA+AA-induced NBT-positive cells. Suppression of TPA+AA-induced ERK protein phosphorylation by PD98059 and NAC was detected, and AA enhanced ERK protein phosphorylation by TPA was in HL-60 cells. AA clearly increased TPA-induced HL-60 cell differentiation, as evidenced by a marked increase in CD11b expression, which was inhibited by NAC and PD98059 addition. Eicosapentaenoic acid (EPA) as well as AA showed increased intracellular peroxide production and differentiation of HL-60 cells elicited by TPA. Evidence of AA potentiation of differentiation by TPA in human leukemia cells HL-60 via activation of ROS-dependent ERK protein phosphorylation was first demonstrated herein.

Concomitant high gene copy number and protein overexpression of IGF1R and EGFR negatively affect disease-free survival of surgically resected non-small-cell-lung cancer patients

BACKGROUND

Insulin-like growth factor 1 receptor (IGF1R) represents a novel molecular target in non-small-cell-lung cancer (NSCLC). IGF1R and epidermal growth factor receptor (EGFR) activation are essential to mediate tumor cell survival, proliferation, and invasion. This study investigates the prognostic role of IGF1R and EGFR in surgically resected NSCLC.

MATERIALS AND METHODS

IGF1R and EGFR copy number gain (CNG) were tested by fluorescence in situ hybridization (FISH) and protein expression by immunohistochemistry (IHC) in 125 stage I-II-IIIA NSCLC patients.

RESULTS

Fourty-six tumors (40.3%) were IGF1R FISH-positive (FISH+), and 76 (67.2%) were EGFR FISH+. Tumors with concomitant IGF1R/EGFR FISH+ were observed in 34 cases (30.1%). IGF1R and EGFR FISH+ were associated with SCC histology (p = 0.01 and p = 0.04, respectively). IGF1R and EGFR protein over-expression (IHC+) were detected in 45 (36.0%) and 69 (55.2%) cases, respectively. Tumors with concomitant IGF1R/EGFR IHC+ were detected in 31 (24.8%) patients. IGF1R/EGFR FISH+ and IGF1R/EGFR IHC+ were significantly associated (χ(2) = 4.02, p = 0.04). Patients with IGF1R/EGFR FISH+ and IGF1R/EGFR IHC+ were associated with shorter disease-free survival (DFS) (p = 0.05 and p = 0.05, respectively). Patients with concomitant IGF1R/EGFR FISH+/IHC+ had a worse DFS and overall survival (p = 0.005 and p = 0.01, respectively). The multivariate model confirmed that IGF1R/EGFR FISH+/IHC+ (hazard ratio (HR), 4.08; p = 0.01) and tumor stage (II-III vs I) (HR, 4.77; p = 0.003) were significantly associated with worse DFS.

CONCLUSIONS

IGF1R/EGFR FISH+ correlates with IGF1R/EGFR IHC+. IGF1R/EGFR FISH+/IHC+ is an independent negative prognostic factor for DFS in early NSCLC. These features may have important implications for future anti-IGF1R therapeutic approaches.

Ligand-free estrogen receptor activity complements IGF1R to induce the proliferation of the MCF-7 breast cancer cells

Background

Ligand-dependent activation of the estrogen receptor (ER) as well as of the insulin-like growth factor type 1 (IGF1R) induces the proliferation of luminal breast cancer cells. These two pathways cooperate and are interdependent. We addressed the question of the mechanisms of crosstalk between the ER and IGF1R.

Methods

We evaluated the mitogenic effects of estradiol (E2; agonist ligand of ER) and of insulin (a ligand of IGF1R) in the MCF-7 cells by flow cytometry and by analyzing the cell levels of cell cycle-related proteins (immunoblotting) and mRNA (RT-QPCR). To verify the requirement for the kinase activity of Akt (a downstream target of IGF1R) in the mitogenic action of estradiol, we used shRNA strategy and shRNA-resistant expression vectors.

Results

The activation of the ER by E2 is unable to induce the cell cycle progression when the phosphatidyl inositol-3 kinase (PI3K)/Akt signaling is blocked by a chemical inhibitor (LY 294002) or by shRNA targeting Akt1 and Akt2. shRNA-resistant Akt wild-type constructs efficiently complemented the mitogenic signaling activity of E2 whereas constructs with inactivated kinase function did not. In growth factor-starved cells, the residual PI3K/Akt activity is sufficient to complement the mitogenic action of E2. Conversely, when ER function is blocked by the antiestrogen ICI 182780, IGF1R signaling is intact but does not lead to efficient reinitiation of the cell cycle in quiescent, growth factor-starved MCF-7 cells. The basal transcription-promoting activity of ligand-free ER in growth factor-starved cells is sufficient to complement the mitogenic action of the IGF1R-dependent signaling.

Conclusions

The basal ER activity in the absence of ligand is sufficient to allow efficient mitogenic action of IGF1R agonists and needs to be blocked to prevent the cell cycle progression.

Gαo potentiates estrogen receptor α activity via the ERK signaling pathway

The estrogen receptor α (ERα) is a transcription factor that mediates the biological effects of 17β-estradiol (E(2)). ERα transcriptional activity is also regulated by cytoplasmic signaling cascades. Here, several Gα protein subunits were tested for their ability to regulate ERα activity. Reporter assays revealed that overexpression of a constitutively active Gα(o) protein subunit potentiated ERα activity in the absence and presence of E(2). Transient transfection of the human breast cancer cell line MCF-7 showed that Gα(o) augments the transcription of several ERα-regulated genes. Western blots of HEK293T cells transfected with ER±Gα(o) revealed that Gα(o) stimulated phosphorylation of ERK 1/2 and subsequently increased the phosphorylation of ERα on serine 118. In summary, our results show that Gα(o), through activation of the MAPK pathway, plays a role in the regulation of ERα activity.

Insulin-like growth factor 1 attenuates antiestrogen- and antiprogestin-induced apoptosis in ER+ breast cancer cells by MEK1 regulation of the BH3-only pro-apoptotic protein Bim

Introduction

In this pre-clinical in vitro study conducted in estrogen receptor positive (ER+) breast cancer cells, we have characterized the effects of insulin-like growth factor I (IGF-1) on the cytostatic and cytotoxic action of antiestrogen treatment when used as a single agent or in combination with the antiprogestin mifepristone (MIF). Our goal was to identify new molecular targets to improve the efficacy of hormonal therapy in breast cancer patients that have a poor response to hormonal therapy, in part, due to high circulating levels of unbound insulinIGF-1.

Methods

IGF-1-mediated effects on cytostasis and apoptotic cell death were determined with cell counts conducted in the presence and absence of trypan blue; enzyme-linked immunosorbent assays to determine the intracellular levels of cleaved cytokeratin 18, a marker of epithelial cancer cell apoptosis; and immunoblot analysis to determine the levels of cleaved poly-ADP ribose polymerase (PARP) and lamin A that result from caspase-dependent apoptosis. Cytotoxicity was further characterized by determination of the levels of reactive oxygen species (ROS) and the percent of mitochondrial membrane depolarization in cell populations treated with the different hormones in the presence and absence of IGF-1. Small molecule inhibitors of the dual-specificity protein kinase MEK1, MEK1 siRNA, Bim siRNA, and vectors overexpressing MEK1 wild type and mutant, dominant negative cDNA were used to identify key IGF-1 downstream prosurvival effectors.

Results

IGF-1, at physiologically relevant levels, blocked the cytotoxic action(s) of the antiestrogens 4-hydroxytamoxifen (4-OHT) and tamoxifen (TAM) when used as single agents or in combination with the antiprogestin MIF. The antiapoptotic action of IGF-1 was mediated primarily through the action of MEK1. MEK1 expression reduced the levels of ROS and mitochondrial membrane depolarization induced by the hormonal treatments via a mechanism that involved the phosphorylation and proteasomal turnover of the proapoptotic BH3-only Bcl-2 family member Bim. Importantly, small-molecule inhibitors of MEK1 circumvented the prosurvival action of IGF-1 by restoring Bim to levels that more effectively mediated apoptosis in ER⁺ breast cancer cells.

Conclusion

his study provides strong support for the use of MEK1 inhibitors in combination with hormonal therapy to effectively affect cytostasis and activate a Bim-dependent apoptotic pathway in ER⁺ breast cancer cells. We discuss that MEK1 blockade may be a particularly effective treatment for women with high circulating levels of IGF-1, which have been correlated to a poor prognosis.

Clinical significance of immunohistochemical expression of insulin-like growth factor-1 receptor and matrix metalloproteinase-7 in resected non-small cell lung cancer

Insulin-like growth factor-1 receptor (IGF-1R) and matrix metalloproteinase-7 (MMP-7) have been reported to be related to tumor invasion and metastasis in various malignancies. The aim of this study was to evaluate the expression levels of IGF-1R and MMP-7 in resected non-small cell lung cancer (NSCLC) and to examine the relationship of such levels to clinical characteristics and survival. Expression was measured immunohistochemically. The percentage of stained cells was multiplied by the staining intensity. The sample was classified as high when the score was equal or higher than the median value or was otherwise considered to be low. High IGF-1R expression was associated with nodal metastasis and recurrence (P=0.034 and 0.006, respectively). High IGF-1R expression was associated with significantly poorer overall survival than low IGF-1R expression (P=0.011). MMP-7 expression did not significantly correlate with any clinicopathological factor. There was a trend toward slightly, but not significantly poorer survival in patients with MMP-7-high tumors than in those with MMP-7-low tumors (P=0.220). There was no significant correlation between IGF-1R expression and MMP-7 expression (P=0.184). Upon multivariate analysis, IGF-1R expression was independently related to the outcomes of patients with NSCLC. Overexpression of IGF-1R may be a useful predictor of lymph node metastasis, recurrence and post-surgical outcomes in patients with NSCLC.

Developmental stage determines estrogen receptor alpha expression and non-genomic mechanisms that control IGF-1 signaling and mammary proliferation in mice

Insulin like growth factor-1 (IGF-1) stimulates increased proliferation and survival of mammary epithelial cells and also promotes mammary tumorigenesis. To study the effects of IGF-1 on the mammary gland in vivo, we used BK5.IGF-1 transgenic (Tg) mice. In these mice, IGF-1 overexpression is controlled by the bovine keratin 5 promoter and recapitulates the paracrine exposure of breast epithelium to stromal IGF-1 that is seen in women. Studies have shown that BK5.IGF-1 Tg mice are more susceptible to mammary tumorigenesis than wild-type littermates. Investigation of the mechanisms underlying increased mammary cancer risk, reported here, revealed that IGF-1 preferentially activated the PI3K/Akt pathway in glands from prepubertal Tg mice, resulting in increased cyclin D1 expression and hyperplasia. However, in glands from postpubertal Tg mice, a pathway switch occurred and activation of the Ras/Raf/MAPK pathway predominated, without increased cyclin D1 expression or proliferation. We further showed that in prepubertal Tg glands, signaling was mediated by formation of an ERα/IRS-1 complex, which activated IRS-1 and directed signaling via the PI3K/Akt pathway. Conversely, in postpubertal Tg glands, reduced ERα expression failed to stimulate formation of the ERα/IRS-1 complex, allowing signaling to proceed via the alternate Ras/Raf/MAPK pathway. These in vivo data demonstrate that changes in ERα expression at different stages of development direct IGF-1 signaling and the resulting tissue responses. As ERα levels are elevated during the prepubertal and postmenopausal stages, these may represent windows of susceptibility during which increased IGF-1 exposure maximally enhances breast cancer risk.

The stimulation of IGF-1R expression by Lewis(y) antigen provides a powerful development mechanism of epithelial ovarian carcinoma

OBJECTIVE

This study aimed to measure and correlate the expression of insulin-like growth factor receptor-1 (IGF-1R) and the Lewis(y) antigen in ovarian cancer cell lines and tissue samples.

METHODS

Reverse transcriptase PCR (RT-PCR), Western blotting, immunoprecipitation, immunohistochemistry, and immunofluorescence double-labeling techniques were applied to detect and measure the expression of Lewis(y) and IGF-1R.

RESULTS

In α1,2-fucosyltransferase (α1,2-FT)-transfected cells, IGF-1R expression was significantly upregulated compared with cells that do not overexpress α1,2-FT (P < 0.05). The amount of Lewis(y) expressed on IGF-1R increased 1.81-fold in α1,2-FT-overexpressing cells (P < 0.05), but the ratio of Lewis(y) expressed on IGF-1R to total IGF-1R was unaltered between two cells (P > 0.05). In malignant epithelial ovarian tumors, the positivity rates of Lewis(y) and IGF-1R detection were 88.3% and 93.33%, respectively, which is higher than the positivity rates in marginal (60.00% and 63.33%, all P < 0.05), benign (33.00% and 53.33%, all P < 0.01), and normal (0% and 40%, all P < 0.01) ovarian samples. No correlations were detected in positivity rates of Lewis(y) or IGF-1R expression with respect to clinicopathological parameters in ovarian cancers (all P > 0.05). Both IGF-1R and Lewis(y) were highly expressed in ovarian cancer tissues, and their expression levels were positively correlated (P < 0.05).

CONCLUSION

Overexpression of Lewis(y) results in overexpression of IGF-1R. Both IGF-1R and Lewis(y) are associated with the occurrence and development of ovarian cancers.

MicroRNA-99a inhibits hepatocellular carcinoma growth and correlates with prognosis of patients with hepatocellular carcinoma

In our in-depth analysis carried out by the Illumina Solexa massive parallel signature sequencing, microRNA-99a (miR-99a) was found to be the sixth abundant microRNA in the miRNome of normal human liver but was markedly down-regulated in hepatocellular carcinoma (HCC). Compelling evidence has suggested the important roles of microRNAs in HCC development. However, the biological function of miR-99a deregulation in HCC remains unknown. In this study, we found that miR-99a was remarkably decreased in HCC tissues and cell lines. Importantly, lower miR-99a expression in HCC tissues significantly correlated with shorter survival of HCC patients, and miR-99a was identified to be an independent predictor for the prognosis of HCC patients. Furthermore, restoration of miR-99a dramatically suppressed HCC cell growth in vitro by inducing the G(1) phase cell cycle arrest. Intratumoral injection of cholesterol-conjugated miR-99a mimics significantly inhibited tumor growth and reduced the α-fetoprotein level in HCC-bearing nude mice. Insulin-like growth factor 1 receptor (IGF-1R) and mammalian target of rapamycin (mTOR) were further characterized as the direct targets of miR-99a. Furthermore, protein levels of IGF-1R and mTOR were found to be inversely correlated with miR-99a expression in HCC tissues. miR-99a mimics inhibited IGF-1R and mTOR pathways and subsequently suppressed expression of cell cycle-related proteins, including cyclin D1 in HCC cells. Conclusively, miR-99a expression was frequently down-regulated in HCC tissues and correlates with the prognosis of HCC patients, thus proposing miR-99a as a prospective prognosis predictor of HCC. miR-99a suppresses HCC growth by inducing cell cycle arrest, suggesting miR-99a as potential tumor suppressor for HCC therapeutics.

Identification of the cathelicidin peptide LL-37 as agonist for the type I insulin-like growth factor receptor

The human cathelicidin antimicrobial protein-18 and its C terminal peptide, LL-37, displays broad antimicrobial activity that is mediated through direct contact with the microbial cell membrane. In addition, recent studies reveal that LL-37 is involved in diverse biological processes such as immunomodulation, apoptosis, angiogenesis and wound healing. An intriguing role for LL-37 in carcinogenesis is also beginning to emerge and the aim of this paper was to explore if and how LL-37 contributes to the signaling involved in tumor development. To this end, we investigated the putative interaction between LL-37 and growth factor receptors known to be involved in tumor growth and progression. Among several receptors tested, LL-37 bound with the highest affinity to insulin-like growth factor 1 receptor (IGF-1R), a receptor that is strongly linked to malignant cellular transformation. Furthermore, this interaction resulted in a dose-dependent phosphorylation and ubiquitination of IGF-1R, with downstream signaling confined to the mitogen-activated protein kinase/extracellular signal-regulated kinase (ERK)-pathway but not affecting phosphatidylinositol 3 kinase/Akt signaling. We found that signaling induced by LL-37 was dependent on the recruitment of β-arrestin to the fully functional IGF-1R and by using mutant receptors we demonstrated that LL-37 signaling is dependent on β-arrestin-1 binding to the C-terminus of IGF-1R. When analyzing the biological consequences of increased ERK activation induced by LL-37, we found that it resulted in enhanced migration and invasion of malignant cells in an IGF-1R/β-arrestin manner, but did not affect cell proliferation. These results indicate that LL-37 may act as a partial agonist for IGF-1R, with subsequent intra-cellular signaling activation driven by the binding of β-arrestin-1 to the IGF-1R. Functional experiments show that LL-37-dependent activation of the IGF-1R signaling resulted in increased migratory and invasive potential of malignant cells.

Computational model of EGFR and IGF1R pathways in lung cancer: a Systems Biology approach for Translational Oncology

In this paper we propose a Systems Biology approach to understand the molecular biology of the Epidermal Growth Factor Receptor (EGFR, also known as ErbB1/HER1) and type 1 Insulin-like Growth Factor (IGF1R) pathways in non-small cell lung cancer (NSCLC). This approach, combined with Translational Oncology methodologies, is used to address the experimental evidence of a close relationship among EGFR and IGF1R protein expression, by immunohistochemistry (IHC) and gene amplification, by in situ hybridization (FISH) and the corresponding ability to develop a more aggressive behavior. We develop a detailed in silico model, based on ordinary differential equations, of the pathways and study the dynamic implications of receptor alterations on the time behavior of the MAPK cascade down to ERK, which in turn governs proliferation and cell migration. In addition, an extensive sensitivity analysis of the proposed model is carried out and a simplified model is proposed which allows us to infer a similar relationship among EGFR and IGF1R activities and disease outcome.

Targeting the insulin-like growth factor I receptor inhibits proliferation and VEGF production of non-small cell lung cancer cells and enhances paclitaxel-mediated anti-tumor effect

The effects of AVE1642, a human monoclonal antibody against IGF-IR, were examined in NSCLC cell lines in order to characterize its anti-proliferative and anti-angiogenic activity as a single agent and in combination with chemotherapy. AVE1642 inhibited IGF-IR signaling and suppressed IGF-I-induced, serum-stimulated or autocrine-mediated proliferation of NSCLC cells in vitro. Furthermore, the combination of paclitaxel and AVE1642 resulted in a sequence-dependent increase in the inhibition of cell proliferation, compared to each agent alone, which was associated with a dose-dependent increase in phosphorylated IGF-IR and Akt. Moreover, inhibition of IGF-IR signaling by AVE1642 reduced IGF-I-induced VEGF production by NSCLC cells as well as the migratory capacity of HUVEC cells challenged with conditioned media from lung cancer cells previously exposed to IGF-I. The above results suggest that inhibition of IGF-IR signaling by AVE1642 enhances the efficacy of chemotherapy and modulates VEGF and angiogenesis in NSCLC. These effects may have important clinical implications in the treatment of NSCLC.

12-O-Tetradecanoyl phorbol-13-acetate (TPA)-induced growth arrest is increased by silibinin by the down-regulation of cyclin B1 and cdc2 and the up-regulation of p21 expression in MDA-MB231 human breast cancer cells

TPA is a potent regulator of cell growth, including cell proliferation and differentiation. In this study, we determined the effect of silibinin on TPA-induced growth arrest in breast cancer cells. Silibinin increased growth arrest of the G2/M phase in a dose-dependent fashion. Silibinin decreased the basal level of cyclin B1 and cdc2 expression, which is involved in S phase and G2/M transition. In addition, TPA-induced G2/M phase arrest was increased by silibinin. Under the same conditions, TPA-induced down-regulation of cyclin B1 and cdc2 was decreased by silibinin. In contrast, TPA-induced p21 expression was further increased by silibinin. To determine the regulatory mechanism of TPA-induced growth arrest, we pretreated cells with various inhibitors, such as UO126, SB203580, and LY294002. Interestingly, TPA-induced growth arrest was significantly increased by LY294002, but not by UO126 and SB203580. In addition, TPA-induced down-regulation of cyclin B1 was inhibited by LY294002; however, the basal level of p21 was increased by TPA and TPA-induced p21 expression was further increased by LY294002. Finally, adenoviral constitutively active-Akt (Ad-CA-Akt) overexpression regulated the up-regulation of cyclin B1 and the down-regulation of p21. Therefore, we have demonstrated that silibinin has an additive effect on TPA-induced growth arrest through the PI-3-kinase/Akt-dependent pathway.

Regulation of ERalpha-mediated transcription of Bcl-2 by PI3K-AKT crosstalk: implications for breast cancer cell survival

Both estrogen, through the estrogen receptor (ER), and growth factors, through the phosphatidylinositol-3-kinase (PI3K)-AKT pathway, have been shown to independently promote cell survival. Here, we investigated the role of ER/PI3K-AKT crosstalk in the regulation of cell survival in MCF-7 breast carcinoma cells. The ER inhibitor ICI 182,780 was used to determine the requirement of the ER for estrogen in the suppression of tumor necrosis factor-alpha (TNFalpha) induced apoptosis. Gene reporter assays and Western blot analyses were used to determine the involvement of the pro-survival factor Bcl-2 and the coactivator GRIP1 in this survival crosstalk. We demonstrated that an intact ER signaling pathway was required for estrogen to suppress apoptosis induced by TNFalpha. Our gene reporter assays revealed that ERalpha, not ERbeta, was targeted by AKT, resulting in transcriptional potentiation of the full-length Bcl-2 promoter, ultimately leading to increased Bcl-2 protein levels. AKT targeted both activation function (AF) domains of the ERalpha for maximal induction of Bcl-2 reporter activity, although the AF-II domain was predominately targeted. In addition, AKT also caused an upregulation of GRIP1 protein levels. Finally, AKT and GRIP1 cooperated to increase Bcl-2 protein expression to a greater level than either factor alone. Collectively, our study suggests a role for ER/PI3K-AKT crosstalk in cell survival and documents the ability of AKT to regulate Bcl-2 expression via differential activation of ERalpha and ERbeta as well as regulation of GRIP1.

Insulin-like growth factor-1 receptor and phosphorylated AKT-serine 473 expression in 132 resected thymomas and thymic carcinomas

BACKGROUND

Thymic malignancies are rare tumors. The insulin-like growth factor-1 (IGF-1)/IGF-1 receptor (IGF-1R) system is involved in the development of the thymus. IGF-1R expression in thymic epithelial malignancies is unknown.

METHODS

The authors investigated the expression of IGF-1R and phosphorylated AKT serine 473 (p-AKT) by using immunohistochemistry and examined the clinicopathologic correlations in a retrospective, single-institution surgical series of 132 patients with thymic epithelial malignancies.

RESULTS

Earlier disease stage, less aggressive histologic types, and complete resection were significant positive prognostic factors for disease-related survival and progression-free survival, and being a woman was a better prognostic factor for disease-related survival. IGF-1R and p-AKT protein levels were expressed in 20% and 36% of thymic tumors, respectively. Both markers were expressed more commonly in recurrent disease than in primary tumors, in more aggressive subtypes, and in more advanced disease stages. There was a trend toward better survival and progression-free survival in patients who were negative for IGF-1R or p-AKT expression in the whole series. When only the 91 primary tumors, IGF1R expression was associated with worse progression-free survival (P < .001).

CONCLUSIONS

The current retrospective analysis demonstrated that disease stage, tumor histology, sex, and resection type were major prognostic factors in the survival of patients with thymic malignancies. The expression levels of IGF-1R and p-AKT in thymic tumors suggested that IGF-1R is a potential target for treatment.

ER-alpha36, a variant of ER-alpha, promotes tamoxifen agonist action in endometrial cancer cells via the MAPK/ERK and PI3K/Akt pathways

Background

Recently, a novel variant of ER-α, ER-α36 was identified and cloned. ER-α36 lacks intrinsic transcription activity and mainly mediates nongenomic estrogen signaling. Here, we studied the role of nongenomic estrogen signaling pathways mediated by ER-α36 in tamoxifen resistance and agonist action.

Methodology

The cellular localization of ER-α36 was examined by immunofluorescence in MCF-7 cells and Hec1A cells. MCF-7 breast cancer cells, MCF-7 cells expressing recombinant ER-α36 (MCF-7/ER36), Hec1A endometrial cancer cells and Hec1A cells with siRNA knockdown of ER-α36 (Hec1A/RNAiER36) were treated with 17β-estradial (E2) and tamoxifen (TAM) in the absence and presence of kinase inhibitor U0126 and LY294002. We examined phosphorylation of signaling molecules and the expression of c-Myc by immunoblotting, and tumor cell growth by MTT assay.

Conclusions

ER variant ER-α36 enhances TAM agonist activity through activation of the membrane-initiated signaling pathways in endometrial cancer, and that ER-α36 is involved in de novo and acquired TAM resistance in breast cancer.

MCF-7 human mammary adenocarcinoma cells exhibit augmented responses to human insulin on a collagen IV surface

Human mammary cell lines are extensively used for preclinical safety assessment of insulin analogs. However, it is essentially unknown how mitogenic responses can be optimized in mammary cell-based systems. We developed an insulin mitogenicity assay in MCF-7 human mammary adenocarcinoma cells, under low serum (0.1% FCS) and phenol red-free conditions, with 3H thymidine incorporation as endpoint. Based on EC50 values determined from 10-fold dilution series, beta-estradiol was the most potent mitogen, followed by human IGF-1, human AspB10 insulin and native human insulin. AspB10 insulin was significantly more mitogenic than native insulin, validating the ability of the assay to identify hypermitogenic human insulin analogs. With MCF-7 cells on a collagen IV surface, the ranking of mitogens was maintained, but fold mitogenic responses and dynamic range and steepness of dose-response curves were increased. Also, PI3K pathway activation by insulin was enhanced on a collagen IV surface. This study provided the first determination and ranking of the mitogenic potencies of standard reference compounds in an optimized MCF-7 assay. The optimized MCF-7 assay described here is of relevance for in vitro toxicological testing and carcinogenicity safety assessment of new insulin compounds.