We have shown that WT-161, a histone deacetylase 6 (HDAC6) inhibitor, shows remarkable anti-tumor activity in multiple myeloma (MM) in preclinical models. However, its activity in other type of cancers has not yet been shown. In this study, we further evaluated the biologic sequelae of WT161 in breast cancer cell lines. WT161 triggers apoptotic cell death in MCF7, T47D, BT474, and MDA-MB231 cells, associated with decreased expression of EGFR, HER2, and ERα and downstream signaling. However, HDAC6 knockdown shows that cytotoxicity and destabilization of these receptors triggered by WT161 are not dependent on HDAC6 inhibition. Moreover WT161 analog MAZ1793, which lacks HDAC inhibitory effect, similarly triggers cell line growth inhibition and downregulation of these receptors. We also confirm that WT161 significantly inhibits in vivo MCF7 cell growth, associated with downregulation of ERα, in a murine xenograft model. Finally, WT161 synergistically enhances bortezomib-induced cytotoxicity, even in bortezomib-resistant breast cancer cells. Our results therefore provide the rationale to develop a novel class of therapeutic agents targeting growth pathways central to the pathogenesis of breast cancer.

Children with high risk sarcoma have a poor prognosis despite surgical resection, irradiation and chemotherapy. Alternative therapies are urgently needed. Urokinase-type plasminogen activator receptor (uPAR) and epidermal growth factor receptor (EGFR) are surface proteins expressed by some pediatric sarcomas. We show for the first time that a de-immunized bispecific ligand toxin, EGFATFKDEL, directed against EGFR and uPAR, successfully targets pediatric sarcoma. Using flow cytometry, we identified a rhabdomyosarcoma (RMS) cell line, RH30, that expresses both uPAR and EGFR, and a Ewing sarcoma (EWS) cell line, TC-71, that expresses only uPAR. We tested the differential sensitivity of these two sarcoma cell lines to toxin-induced killing, using both in vitro assays and an in vivo murine model. We show that pediatric sarcomas are highly sensitive to EGFATFKDEL (at subnanomolar concentrations) in vitro. In vivo, tumor growth was significantly attenuated after treatment with EGFTFKDEL, compared to untreated controls, in both RH30 and TC-71 tumor bearing mice. In addition, we found that simultaneously targeting both receptors in a dual positive cell line was more effective than targeting a single receptor or antigen, resulting in a greater tumor response, including complete tumor regression in an animal model of bulky disease. Our findings provide support for further exploration of bispecific targeting of pediatric sarcomas with bispecific ligand toxins, such as EGFATFKDEL.

Many studies have suggested that disialogangliosides, GD2 and GD3, are involved in the development of various tumor types. However, the functional relationships between ganglioside expression and cancer development or aggressiveness are not fully described. GD3 is upregulated in approximately half of all invasive ductal breast carcinoma cases, and enhanced expression of GD3 synthase (GD3S, alpha-N-acetylneuraminide alpha-2,8-sialyltransferase) in estrogen receptor-negative breast tumors, was shown to correlate with reduced overall patient survival. We previously found that GD2 and GD3, together with their common upstream glycosyltransferases, GD3S and GD2/GM2 synthase, maintain a stem cell phenotype in breast cancer stem cells (CSCs). In the current study, we demonstrate that GD3S alone can sustain CSC properties and also promote malignant cancer properties. Using MALDI-MS and flow cytometry, we found that breast cancer cell lines, of various subtypes with or without ectopic GD3S-expression, exhibited distinct GD2/GD3 expression profiles. Furthermore, we found that GD3 was associated with EGFR and activated EGFR signaling in both breast CSCs and breast cancer cell lines. In addition, GD3S knockdown enhanced cytotoxicity of the EGFR-inhibitor gefitinib in resistant MDA-MB468 cells, both in vitro and in vivo. Based on this evidence, we propose that GD3S contributes to gefitinib-resistance in EGFR-positive breast cancer cells and may be an effective therapeutic target in drug-resistant breast cancers.

Platelet-derived growth factor (PDGF) signaling, besides other growth factor-mediated signaling pathways like vascular endothelial growth factor (VEGF) and epidermal growth factor (EGF), seems to play a crucial role in tumor development and progression. We have recently provided evidence for upregulation of PDGF expression in UICC stage I-IV primary colorectal cancer (CRC) and demonstrated PDGF-mediated induction of PI3K/Akt/mTOR signaling in CRC cell lines. The present study sought to follow up on our previous findings and explore the alternative receptor cross-binding potential of PDGF in CRC. Our analysis of primary human colon tumor samples demonstrated upregulation of the PDGFRβ, VEGFR1, and VEGFR2 genes in UICC stage I-III tumors. Immunohistological analysis revealed co-expression of PDGF and its putative cross-binding partners, VEGFR2 and EGFR. We then analyzed several CRC cell lines for PDGFRα, PDGFRβ, VEGFR1, and VEGFR2 protein expression and found these receptors to be variably expressed amongst the investigated cell lines. Interestingly, whereas Caco-2 and SW480 cells showed expression of all analyzed receptors, HT29 cells expressed only VEGFR1 and VEGFR2. However, stimulation of HT29 cells with PDGF resulted in upregulation of VEGFR1 and VEGFR2 expression despite the absence of PDGFR expression and mimicked the effect of VEGF stimulation. Moreover, PDGF recovered HT29 cell proliferation under simultaneous treatment with a VEGFR or EGFR inhibitor. Our results provide some of the first evidence for PDGF cross-signaling through alternative receptors in colorectal cancer and support anti-PDGF therapy as a combination strategy alongside VEGF and EGF targeting even in tumors lacking PDGFR expression.

The involvement of ErbB family members in breast cancer progression and metastasis has been demonstrated by many studies. However, the downstream effectors that mediate their migratory and invasive responses have not been fully explored. In this study, we show that the non-receptor tyrosine kinase PYK2 is a key effector of EGFR and HER2 signaling in human breast carcinoma. We found that PYK2 is activated by both EGF and heregulin (HRG) in breast cancer cells, and positively regulates EGF/HRG-induced cell spreading, migration and invasion. PYK2 depletion markedly affects ERK1/2 and STAT3 phosphorylation in response to EGF/HRG as well as to IL8 treatment. Importantly, PYK2 depletion also reduced EGF/HRG-induced MMP9 and IL8 transcription, while IL8 inhibition abrogated EGF-induced MMP9 transcription and attenuated cell invasion. IL8, which is transcriptionally regulated by STAT3 and induces PYK2 activation, prolonged EGF-induced PYK2, STAT3 and ERK1/2 phosphorylation suggesting that IL8 acts through an autocrine loop to reinforce EGF-induced signals. Collectively our studies suggest that PYK2 is a common downstream effector of ErbB and IL8 receptors, and that PYK2 integrates their signaling pathways through a positive feedback loop to potentiate breast cancer invasion. Hence, PYK2 could be a potential therapeutic target for a subset of breast cancer patients.

Data about the expression of Epidermal Growth Factor Receptors (EGFRs) in colorectal adenomas remain scarce.

Bee venom (BV) has been used as a traditional medicine to treat arthritis, rheumatism, back pain, cancerous tumors, and skin diseases. However, the effects of BV on the colon cancer and their action mechanisms have not been reported yet. We used cell viability assay and soft agar colony formation assay for testing cell viability, electro mobility shift assay for detecting DNA binding activity of nuclear factor kappa B (NF-κB) and Western blotting assay for detection of apoptosis regulatory proteins. We found that BV inhibited growth of colon cancer cells through induction of apoptosis. We also found that the expression of death receptor (DR) 4, DR5, p53, p21, Bax, cleaved caspase-3, cleaved caspase-8, and cleaved caspase-9 was increased by BV treatment in a dose dependent manner (0-5 μg/ml). Consistent with cancer cell growth inhibition, the DNA binding activity of nuclear factor kappa B (NF-κB) was also inhibited by BV treatment. Besides, we found that BV blocked NF-κB activation by directly binding to NF-κB p50 subunit. Moreover, combination treatment with BV and p50 siRNA or NF-κB inhibitor augmented BV-induced cell growth inhibition. However, p50 mutant plasmid (C62S) transfection partially abolished BV-induced cell growth inhibiton. In addition, BV significantly suppressed tumor growth in vivo. Therefore, these results suggested that BV could inhibit colon cancer cell growth, and these anti-proliferative effects may be related to the induction of apoptosis by activation of DR4 and DR5 and inhibition of NF-κB.

Glucagon secretion involves a combination of paracrine, autocrine, hormonal, and autonomic neural mechanisms. Type 2 diabetes often presents impaired glucagon suppression by insulin and glucose. Insulin-like growth factor-I (IGF-1) has elevated homology with insulin, and regulates pancreatic β-cells insulin secretion. Insulin and IGF-1 receptors share considerable structure homology and function. We hypothesized the existence of a mechanism linking the inhibition of α-cells glucagon secretion to IGF-1. Herein, we evaluated the association between plasma IGF-1 and glucagon levels in 116 nondiabetic adults. After adjusting for age gender and BMI, fasting glucagon levels were positively correlated with 2-h post-load glycaemia, HOMA index and fasting insulin, and were negatively correlated with IGF-1 levels. In a multivariable regression, the variables independently associated to fasting glucagon were circulating IGF-1 levels, HOMA index and BMI, explaining 20.7% variation. To unravel the molecular mechanisms beneath IGF-1 and glucagon association, we investigated whether IGF-1 directly modulates glucagon expression and secretion in an in vitro model of α-cells. Our data showed that IGF-1 inhibits the ability of low glucose concentration to stimulate glucagon expression and secretion via activation of the phosphatidylinositol-3-kinase/Akt/FoxO1 pathway. Collectively, our results suggest a new regulatory role of IGF-1 on α-cells biological function.

The transcription factor Kruppel-like factor 2 (KLF2) displays anticarcinogenic activities but the mechanism that underlies this activity is unknown. We show here that KLF2 is markedly downregulated in human breast cancers and that its expression positively correlates with breast cancer patient survival. We show further that KLF2 suppresses tumor development by controlling the transcriptional activity of the vitamin A metabolite retinoic acid (RA). RA regulates gene transcription by activating two types of nuclear receptors: RA receptors (RARs), which inhibit tumor development, and peroxisome proliferator-activated receptor β/δ (PPARβ/δ), which promotes tumorigenesis. The partitioning of RA between these receptors is regulated by two carrier proteins: cellular retinoic acid-binding protein 2 (CRABP2), which delivers RA to RARs, and fatty acid-binding protein 5 (FABP5), which shuttles ligands to PPARβ/δ. We show that KLF2 induces the expression of CRABP2 and RARγ and inhibits the expression FABP5 and PPARβ/δ thereby shifting RA signaling from the pro-carcinogenic FABP5/PPARβ/δ to the growth-suppressing CRABP2/RAR path. The data thus reveal that KLF2 suppresses tumor growth by controlling the transcriptional activities of RA.

We have recently demonstrated that, fibroblast growth factor 2 (FGFR2), signalling via ribosomal S6 kinase 2 (RSK2), promotes progression of breast cancer (BCa). Loss of progesterone receptor (PR), whose activity in BCa cells can be stimulated by growth factor receptors (GFRs), is associated with poor patient outcome. Here we showed that FGF7/FGFR2 triggered phosphorylation of PR at Ser294, PR ubiquitination and subsequent receptor`s degradation via the 26S proteasome pathway in BCa cells. We further demonstrated that RSK2 mediated FGF7/FGFR2-induced PR downregulation. In addition, a strong synergistic effect of FGF7 and progesterone (Pg), reflected in the enhanced anchorage-independent growth and cell migration, was observed. Analysis of clinical material demonstrated that expression of PR inversely correlated with activated RSK (RSK-P) (p = 0.016). Patients with RSK-P(+)/PR(-) tumours had 3.629-fold higher risk of recurrence (p = 0.002), when compared with the rest of the cohort. Moreover, RSK-P(+)/PR(-) phenotype was shown as an independent prognostic factor (p = 0.006). These results indicate that the FGF7/FGFR2-RSK2 axis promotes PR turnover and activity, which may sensitize BCa cells to stromal stimuli and contribute to the progression toward steroid hormone negative BCa.

Basic fibroblast growth factor (bFGF) has been implicated in tumor growth via interactions with its receptors (FGFRs) on the cell surface and therefore, bFGF/FGFRs are considered essential targets for cancer therapy. Herein, a consensus heptapeptide (LSPPRYP) was identified for the first time from a phage display heptapeptide library after three sequential rounds of biopanning against FGFR-expressing cells with competitive displacement of phage by bFGF, followed by subtraction of non-specific binding by FGFR-deficient cells. Phage bearing LSPPRYP showed high levels of binding to Balb/c 3T3 cells expressing high-affinity bFGF-binding FGFR (bFGFR), but not to the cells that do not express bFGFR (Cos-7), or express a very low affinity bFGFR (HaCat). The selected-phage-derived peptide synthesized by solid phase method using a rapid and practical Fmoc strategy was found to specifically compete with bFGF for binding to its receptors, inhibit bFGF-stimulated cell proliferation by inducing cell cycle arrest, and block bFGF-induced activation of Erk1 and Erk2 kinase in B16-F10 melanoma cells. Importantly, treatment of melanoma-bearing mice with the synthetic peptide significantly suppressed tumor growth. The results demonstrate a strong anticancer activity of the isolated bFGFR-binding peptide (and its future derivatives), which may have great potential for cancer therapy.

Despite recent progress in advanced melanoma therapy, identification of signalling pathways involved in melanoma switch from proliferative to invasive states is still crucial to uncover new therapeutic targets for improving the outcome of metastatic disease. Neuropilin-1 (NRP-1), a co-receptor for vascular endothelial growth factor-A (VEGF-A) tyrosine kinase receptors (VEGFRs), has been suggested to play a relevant role in melanoma progression. NRP-1 can be activated by VEGF-A also in the absence of VEGFRs, triggering specific signal transduction pathways (e.g. p130Cas phosphorylation). Since melanoma cells co-expressing high levels of NRP-1 and platelet derived growth factor-C (PDGF-C) show a highly invasive behaviour and PDGF-C shares homology with VEGF-A, in this study we have investigated whether PDGF-C directly interacts with NRP-1 and promotes melanoma aggressiveness. Results demonstrate that PDGF-C specifically binds in vitro to NRP-1. In melanoma cells expressing NRP-1 but lacking PDGFRα, PDGF-C stimulates extra-cellular matrix (ECM) invasion and induces p130Cas phosphorylation. Blockade of PDGF-C function by neutralizing antibodies or reduction of its secretion by specific siRNA inhibit ECM invasion and vasculogenic mimicry. Moreover, PDGF-C silencing significantly down-modulates the expression of Snail, a transcription factor involved in tumour invasiveness that is highly expressed in NRP-1 positive melanoma cells. In conclusion, our results demonstrate for the first time a direct activation of NRP-1 by PDGF-C and strongly suggest that autocrine and/or paracrine stimulation of NRP-1 by PDGF-C might contribute to the acquisition of a metastatic phenotype by melanoma cells.

Designated for cyclic shedding, the endometrial stroma is rich in endometrial mesenchymal stem cells (EMSCs) and may play an important role in the development of endometrial carcinoma (EC). This study characterized the crosstalk of EC cells with EMSCs and the resultant effects on malignant phenotypes. The cultured EMSCs expressed CD73, CD90, and CD105, but not CD14, CD19, CD34, CD45, or human leukocyte antigen-antigen D related markers. These EMSCs also showed osteogenic, adipogenic, and chondrogenic differentiation ability. Transforming growth factor (TGF)-β1 and C-X-C motif chemokine ligand 12 (CXCL12) secretion or expression were reciprocally enhanced in EC cells and EMSCs, as well as in their tissues. By acting on the receptors expressed in their mutual target cells, the interaction between TGF-β and CXCL12 results in the enhanced migration, invasion, tumorigenesis, and epithelial-mesenchymal transition of EC cells, which can be blocked by neutralizing the antibody of either CXCL12 or C-X-C chemokine receptor type 4. The study revealed unprecedented paracrine interactions between EC cells and EMSCs that resulted in the enhancement of transformation phenotypes. Thus, the blocking of TGF-β or CXCL12 signaling can be a therapeutic target for EC.

Aberrant activation of the Sonic Hedgehog (SHH) gene is observed in various cancers. Previous studies have shown a "cross-talk" effect between the canonical Hedgehog signaling pathway and the Epidermal Growth Factor (EGF) pathway when SHH is active in the presence of EGF. However, the precise mechanism of the cross-talk effect on the entire gene population has not been investigated. Here, we re-analyzed publicly available data to study how SHH and EGF cooperate to affect the dynamic activity of the gene population. We used genome dynamic analysis to explore the expression profiles under different conditions in a human medulloblastoma cell line. Ordinary differential equations, equipped with solid statistical and computational tools, were exploited to extract the information hidden in the dynamic behavior of the gene population. Our results revealed that EGF stimulation plays a dominant role, overshadowing most of the SHH effects. We also identified cross-talk genes that exhibited expression profiles dissimilar to that seen under SHH or EGF stimulation alone. These unique cross-talk patterns were validated in a cell culture model. These cross-talk genes identified here may serve as valuable markers to study or test for EGF co-stimulatory effects in an SHH+ environment. Furthermore, these cross-talk genes may play roles in cancer progression, thus they may be further explored as cancer treatment targets.

Nerve growth factor (NGF)/nerve growth factor receptors (NGFRs) axis and canonical WNT/β-catenin pathway have shown to play crucial roles in tumor initiation, progression and prognosis. But little did we know the relationship between them in modulation of tumor progress. In this report, we found that NGF/NGFRs and β-catenin were coexpression in ovarian cancer cell lines, and NGF can decrease the expression level of β-catenin and affect its activities, which may be related to the NGF-induced down-regulation of B-cell CLL/lymphoma 9-like (BCL9L, BCL9-2). Furthermore, NGF can also increase or decrease the downstream target gene expression levels of WNT/β-catenin depending on the cell types. Especially, we created a novel in vitro cell growth model based on a microfluidic device to intuitively observe the effects of NGF/NGFRs on the motility behaviors of ovarian cancer cells. The results showed that the migration area and maximum distance into three dimensional (3D) matrigel were decreased in CAOV3 and OVCAR3 cells, but increased in SKOV3 cells following the stimulation with NGF. In addition, we found that the cell colony area was down-regulated in CAOV3 cells, however, it was augmented in OVCAR3 cells after treatment with NGF. The inhibitors of NGF/NGFRs, such as Ro 08-2750, K252a and LM11A-31,can all block NGF-stimulated changes of gene expression or migratory behavior on ovarian cancer cells. The different results among ovarian cancer cells illustrated the heterogeneity and complexity of ovarian cancer. Collectively, our results suggested for the first time that NGF is functionally linked to β-catenin in the migration of human ovarian cancer cells, which may be a novel therapeutic perspective to prevent the spread of ovarian carcinomas by studying the interaction between NGF/NGFRs and canonical WNT/β-catenin signaling.

The estrogen receptor (ER) promotes non-small cell lung cancer (NSCLC) proliferation. Since fibroblast growth factors (FGFs) are known regulators of stem cell markers in ER positive breast cancer, we investigated whether a link between the ER, FGFs, and stem cell markers exists in NSCLC. In lung preneoplasias and adenomas of tobacco carcinogen exposed mice, the anti-estrogen fulvestrant and/or the aromatase inhibitor anastrozole blocked FGF2 and FGF9 secretion, and reduced expression of the stem cell markers SOX2 and nanog. Mice administered β-estradiol during carcinogen exposure showed increased FGF2, FGF9, SOX2, and Nanog expression in airway preneoplasias. In normal FGFR1 copy number NSCLC cell lines, multiple FGFR receptors were expressed and secreted several FGFs. β-estradiol caused enhanced FGF2 release, which was blocked by fulvestrant. Upon co-inhibition of ER and FGFRs using fulvestrant and the pan-FGFR inhibitor AZD4547, phosphorylation of FRS2, the FGFR docking protein, was maximally reduced, and enhanced anti-proliferative effects were observed. Combined AZD4547 and fulvestrant enhanced lung tumor xenograft growth inhibition and decreased Ki67 and stem cell marker expression. To verify a link between ERβ, the predominant ER in NSCLC, and FGFR signaling in patient tumors, mRNA analysis was performed comparing high versus low ERβ expressing tumors. The top differentially expressed genes in high ERβ tumors involved FGF signaling and human embryonic stem cell pluripotency. These results suggest interaction between the ER and FGFR pathways in NSCLC promotes a stem-like state. Combined FGFR and ER inhibition may increase the efficacy of FGFR inhibitors for NSCLC patients lacking FGFR genetic alterations.

The mannose 6-phosphate/insulin-like growth factor II receptor (M6P/IGF2R) binds M6P-capped ligands and IGF-II at different binding sites within the ectodomain and mediates ligand internalization and trafficking to the lysosome. Multivalent M6P-based ligands can cross-bridge the M6P/IGF2R, which increases the rate of receptor internalization, permitting IGF-II binding as a passenger ligand and subsequent trafficking to the lysosome, where the IGF-II is degraded. This unique feature of the receptor may be exploited to design novel therapeutic agents against IGF-II-dependent cancers that will lead to decreased bioavailable IGF-II within the tumor microenvironment. We have designed a panel of M6P-based ligands that bind to the M6P/IGF2R with high affinity in a bivalent manner and cause decreased cell viability. We present evidence that our ligands bind through the M6P-binding sites of the receptor and facilitate internalization and degradation of IGF-II from conditioned medium to mediate this cellular response. To our knowledge, this is the first panel of synthetic bivalent ligands for the M6P/IGF2R that can take advantage of the ligand-receptor interactions of the M6P/IGF2R to provide proof-of-principle evidence for the feasibility of novel chemotherapeutic agents that decrease IGF-II-dependent growth of cancer cells.

Lung cancer remains the leading cause of cancer-related deaths worldwide. β-arrestin-1 (ARRB1), a scaffolding protein involved in the desensitization of signals arising from activated G-protein-coupled receptors (GPCRs), has been shown to play a role in invasion and proliferation of cancer cells, including nicotine-induced proliferation of human non-small cell lung cancers (NSCLCs). In this study, we identified genes that are differentially regulated by nicotine in an ARRB1/β-arrestin-1 dependent manner in NSCLC cells by microarray analysis. Among the identified genes, SCF (Stem cell factor) strongly differentiated smokers from non-smokers in the Director's Challenge Set expression data and its high expression correlated with poor prognosis. SCF, a major cytokine is the ligand for the c-Kit proto-oncogene and was found to be over expressed in human lung adenocarcinomas, but not squamous cell carcinomas. Data presented here show that transcription factor E2F1 can induce SCF expression at the transcriptional level and depletion of E2F1 or ARRB1/β-arrestin-1 could not promote self-renewal of SP cells. These studies suggest that nicotine might be promoting NSCLC growth and metastasis by inducing the secretion of SCF, and raise the possibility that targeting signalling cascades that activate E2F1 might be an effective way to combat NSCLC.

Neuroblastoma is the most common extracranial tumor in children. Despite aggressive multimodal treatment, high-risk neuroblastoma remains a clinical challenge with survival rates below 50%. Adding targeted drugs to first-line therapy regimens is a promising approach to improve survival in these patients. TACR1 activation by substance P has been reported to be mitogenic in cancer cell lines. Tachykinin receptor (TACR1) antagonists are approved for clinical use as an antiemetic remedy since 2003. Tachykinin receptor inhibition has recently been shown to effectively reduce growth of several tumor types. Here, we report that neuroblastoma cell lines express TACR1, and that targeting TACR1 activity significantly reduced cell viability and induced apoptosis in neuroblastoma cell lines. Gene expression profiling revealed that TACR1 inhibition repressed E2F2 and induced TP53 signaling. Treating mice harboring established neuroblastoma xenograft tumors with Aprepitant also significantly reduced tumor burden. Thus, we provide evidence that the targeted inhibition of tachykinin receptor signaling shows therapeutic efficacy in preclinical models for high-risk neuroblastoma.

The local renin-angiotensin system (RAS) and insulin-like growth factor 1 (IGF-1) have been involved in longevity, neurodegeneration and aging-related dopaminergic degeneration. However, it is not known whether IGF-1 and angiotensin-II (AII) activate each other. In the present study, AII, via type 1 (AT1) receptors, exacerbated neuroinflammation and dopaminergic cell death. AII, via AT1 receptors, also increased the levels of IGF-1 and IGF-1 receptors in microglial cells. IGF-1 inhibited RAS activity in dopaminergic neurons and glial cells, and also inhibited the AII-induced increase in markers of the M1 microglial phenotype. Consistent with this, IGF-1 decreased dopaminergic neuron death induced by the neurotoxin MPP+ both in the presence and in the absence of glia. Intraventricular administration of AII to young rats induced a significant increase in IGF-1 expression in the nigral region. However, aged rats showed decreased levels of IGF-1 relative to young controls, even though RAS activity is known to be enhanced in aged animals. The study findings show that IGF-1 and the local RAS interact to inhibit or activate neuroinflammation (i.e. transition from the M1 to the M2 phenotype), oxidative stress and dopaminergic degeneration. The findings also show that this mechanism is impaired in aged animals.