Insulin-like Growth Factor-1 Inhibitor Research Articles

Role of the IGF-1 Axis in Overcoming Resistance in Breast Cancer.

Over the last two decades, many studies have demonstrated that the insulin-like growth factor-1 (IGF-1) is involved in a number of patho-physiological processes, as well as in the development of different types of solid tumors, including breast cancer (BC). Preclinical and clinical data showed that IGF-1 receptor (R) is overexpressed and hyper-phosphorylated in several subtypes of BCs. The central implications of this pathway in tumor cell proliferation and metastasis make it an important therapeutic target. Moreover, the IGF-1 axis has shown strong interconnection with estrogen regulation and endocrine therapy, suggesting a possible solution to anti-estrogen resistance. IGF-1R might also interfere with other pivotal therapeutic strategies, such as anti HER2 treatments and mTOR inhibitors; several clinical trials are ongoing evaluating the role of IGF-1R inhibition in modulating resistance mechanisms to target therapies. Our aim is to offer an overview of the most recent and significant field of application of IGF-1 inhibitors and relevant therapeutic strategies, weighing their possible future impact on clinical practice.

Update on etiopathogenesis and treatment of Acne.

Acne, the most common skin disease, is a disorder of pilosebaceous units that affects adolescents mainly and adults occasionally. The pathogenesis is multifactorial. Besides genetic predisposition, other major factors include the action of androgens, pro-inflammatory lipids acting as ligands of peroxisome proliferator-activated receptors in the sebocytes, toll-like receptor-2 acting on keratinocytes, recognition of pathogen-associated molecular patterns, cytokines, chemokines, inflammasomes, neuroendocrine regulatory mechanisms, diet and other pro-inflammatory targets implicated in the activation of immune detection and response. Most of these factors converge on mammalian target of rapamycin complex1 (mTORC1) activation which is further enhanced by the nutrient signaling of Western diet. This multitude of pathogenic factors has led to a new armamentarium of drugs for the treatment of acne. Topical anti-androgens, insulin-like growth factor-1 inhibitors, peroxisome proliferator-activated receptor-modulators, acetylcholine inhibitors, topical retinoic acid metabolism-blocking agents, vitamin D analogues, antimicrobial peptides, interleukin-1α and interleukin-1β blockers and immunotherapy are some of the novel treatment options.

Periodic dieting promotes health

Adherence to a periodic fast-mimicking diet improves health and promotes longevity.

ATM regulates insulin-like growth factor 1-secretory clusterin (IGF-1-sCLU) expression that protects cells against senescence.

Downstream factors that regulate the decision between senescence and cell death have not been elucidated. Cells undergo senescence through three pathways, replicative senescence (RS), stress-induced premature senescence (SIPS) and oncogene-induced senescence. Recent studies suggest that the ataxia telangiectasia mutant (ATM) kinase is not only a key protein mediating cellular responses to DNA damage, but also regulates cellular senescence induced by telomere end exposure (in RS) or persistent DNA damage (in SIPS). Here, we show that expression of secretory clusterin (sCLU), a known pro-survival extracellular chaperone, is transcriptionally up-regulated during both RS and SIPS, but not in oncogene-induced senescence, consistent with a DNA damage-inducible mechanism. We demonstrate that ATM plays an important role in insulin-like growth factor 1 (IGF-1) expression, that in turn, regulates downstream sCLU induction during senescence. Loss of ATM activity, either by genomic mutation (ATM-deficient fibroblasts from an ataxia telangiectasia patient) or by administration of a chemical inhibitor (AAI, an inhibitor of ATM and ATR), blocks IGF-1-sCLU expression in senescent cells. Downstream, sCLU induction during senescence is mediated by IGF-1R/MAPK/Egr-1 signaling, identical to its induction after DNA damage. In contrast, administration of an IGF-1 inhibitor caused apoptosis of senescent cells. Thus, IGF-1 signaling is required for survival, whereas sCLU appears to protect cells from premature senescence, as IMR-90 cells with sCLU knockdown undergo senescence faster than control cells. Thus, the ATM-IGF-1-sCLU pathway protects cells from lethality and suspends senescence.

The Effects of Insulin-like Growth Factor 1 and Growth Hormone on Human Meibomian Gland Epithelial Cells

A phase 1 study has reported that dry eye disease is the most common adverse effect of human exposure to the antibody figitumumab, an anticancer drug that prevents insulin-like growth factor 1 (IGF-1) from binding to its receptor. We hypothesized that the mechanism underlying this effect is the inhibition of IGF-1 action in epithelial cells of the meibomian gland. To test the hypothesis that IGF-1 stimulates meibomian gland function in vitro and to examine whether growth hormone, a closely related hormone of IGF-1, has the same effect. DESIGN, SETTING, AND MATERIAL: Immortalized human meibomian gland epithelial cells were cultured in the presence or the absence of IGF-1, growth hormone, and an IGF-1 receptor-blocking antibody. Signaling pathways, cell proliferation, neutral lipid staining, and a key protein involved in lipid biogenesis were evaluated. Application of IGF-1 and growth hormone to human meibomian gland epithelial cells. Immunoblotting, cell counting, and neutral lipid staining. RESULTS Insulin-like growth factor 1 activated the phosphoinositol 3-kinase/Akt and forkhead box O1 pathways (showing a dose-dependent effect on immunoblotting), stimulated cellular proliferation (about 1.8-fold increase in cell number), increased sterol regulatory element-binding protein 1 expression (about 3-fold increase on immunoblotting), and promoted lipid accumulation in human meibomian gland epithelial cells (about 2-fold increase in lipid staining). These IGF-1 actions, which may be blocked by cotreatment with the anti-IGF-1 antibody, were accompanied by inconsistent effects on extracellular signal-regulated kinase phosphorylation. We were not able to demonstrate activation of Akt, forkhead box O1, extracellular signal-regulated kinase, Janus kinase 2, or signal transducers and activators of transcription 5, induced cell proliferation, or lipid accumulation in these cells by growth hormone application. Our results support the hypothesis that IGF-1 acts on human meibomian gland epithelial cells and may explain why treatment with figitumumab, the IGF-1 inhibitor, causes dry eye disease. Ophthalmic care for dry eye disease may be needed when patients with cancer undergo treatment with drugs that inhibit IGF-1 action.

Abstract 3235: The IGF1 inhibitor BMS-754807 synergizes with Lapatinib in colorectal cancer cell lines

Abstract Colorectal cancer is the second leading cause of cancer deaths worldwide. Early screening has improved survival rates, but at the time of diagnosis, a significant percentage of patients have advanced disease. Despite improved chemotherapy regimens, the average rate of survival remains less than two years. Drugs that target the epidermal growth factor (EGF) pathway have proven to be beneficial in patients who retain a wild-type KRAS. However 40% of colorectal tumors have a mutated KRAS, and are resistant to EGF-based therapies. One new approach is to target pathways that regulate cancer cell metabolism. The insulin-like growth factor-1 (IGF1) pathway regulates cell growth and motility, activates anti-apoptotic pathways and increases the frequency of cancer stem cells (CSCs). We have previously shown that inhibition of IGF1 signaling with a monoclonal antibody that blocks the IGF1R receptor, inhibited metastasis. In the current study, we examined whether simultaneous inhibition of the IGF1 and EGF pathways would be sufficient to block AKT activation and induce cell death, and also whether the dual targeting of these pathways would increase the cytotoxicity of other anticancer therapies. We report here that the small molecule inhibitor BMS-754807, which blocks the IGF1 and insulin receptors with equal potency, effectively kills a panel of 8 human colorectal cancer cell lines as determined using cell viability assays. The IGF-1R/IR dual inhibitor was found to reduce the size of the cancer stem cell population in several cell lines when measured by side-population analysis. No additional cell death was observed when the IGF1 inhibitor was used in combination with 5-FU and Irinotecan, however, when BMS-754807 was combined with an EGF pathway inhibitor synergy in the induction of cell death was observed in a subset of colorectal cancer cell lines. This effect was seen with the EGFR small molecule inhibitor Lapatinib, but not with the monoclonal antibody Cetuximab. While both Lapatinib and Cetuximab inhibited ERK activation, AKT activation was only inhibited by combination therapy with BMS-754807 and Lapatinib. EGFR activation was, furthermore, inhibited by BMS-754807 alone indicating that there may be cross-talk between the two pathways. We have previously reported that Lapatinib has off target effects in colorectal cancer cell lines, which require higher doses of Lapatinib and induction of DR5 via the JNK pathway. We are currently investigating whether the observed synergy between Lapatinib and BMS-754807 involves off target effects of Lapatinib, although the synergy observed is at doses thought to specifically target the EGFR family. The synergy between BMS-754807 and Lapatinib was observed in cell lines that have mutant BRAF as well as in those with mutant KRAS. This drug combination may consequently provide a new potential treatment strategy for patients who do not derive benefit from current EGFR-based therapies. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 3235. doi:1538-7445.AM2012-3235

Decoy Receptor 3 Expression in AsPC-1 Human Pancreatic Adenocarcinoma Cells via the Phosphatidylinositol 3-Kinase-, Akt-, and NF-κB-Dependent Pathway

Many cancers develop different means of escaping destruction by the immune system, such as resistance to Fas ligand (FasL)-Fas interaction-mediated apoptotic signals. Decoy receptor 3 (DcR3), a soluble receptor for FasL, is highly expressed in cancer cells and plays a significant role in immune suppression and tumor progression. However, how DcR3 expression is modulated is unclear. In this study, immunoprecipitation and ELISA using human pancreatic cancer cells showed the presence of high levels of DcR3 protein in AsPC-1 cells, but not in PANC-1 cells. Treatment with herbimycin A (a tyrosine kinase inhibitor), LY294002 or wortmannin (PI3K inhibitors), pyrrolidine dithiocarbamate (an NF-kappaB inhibitor), or AG1024 (an insulin-like growth factor-1 inhibitor) significantly reduced endogenous DcR3 levels in AsPC-1 cells. Furthermore, transfection of AsPC-1 cells with Akt or IkappaBalpha dominant-negative plasmids also markedly reduced DcR3 levels. In contrast, 48-h transfection of PANC-1 cells with a constitutively active Akt induced DcR3 expression. Flow cytometry assays indicated that apoptosis was not seen in AsPC-1 cells incubated with soluble FasL or membrane-bound FasL, but was seen when DcR3 small interfering RNA-transfected AsPC-1 cells underwent the same treatment. In addition, PANC-1 cell incubation with conditioned medium from AsPC-1 cells transfected with dominant-negative Akt or IkappaBalpha plasmids or DcR3 small interfering RNA showed increased soluble FasL-mediated apoptosis compared with the control group. Our results show that insulin-like growth factor-1-induced activation of the PI3K/Akt/NF-kappaB signaling pathway is involved in the modulation of endogenous DcR3 expression in AsPC-1 cells, and that reducing endogenous DcR3 levels increases FasL-induced apoptosis of human pancreatic cancer cells.

Tyrphostin AG 1024 modulates radiosensitivity in human breast cancer cells

Insulin-like growth factor-1 (IGF-1) plays an important growth-promoting effect by activating the PI3K/Akt signalling pathway, inhibiting apoptotic pathways and mediating mitogenic actions. Tyrphostin AG 1024, one selective inhibitor of IGF-1R, was used to evaluate effects on proliferation, radiosensitivity, and radiation-induced cell apoptosis in a human breast cancer cell line MCF-7. Exposure to Tyrphostin AG 1024 inhibited proliferation and induced apoptosis in a time-dependent manner, and the degree of growth inhibition for IC20 plus irradiation (4 Gy) was up to 50% compared to the control. Examination of Tyrphostin AG 1024 effects on radiation response demonstrated a marked enhancement in radiosensitivity and amplification of radiation-induced apoptosis. Western blot analysis indicated that Tyrphostin AG 1024-induced apoptosis was associated with a downregulation of expression of phospho-Akt1, increased expression of Bax, p53 and p21, and a decreased expression of bcl-2 expression, especially when combined with irradiation. To our knowledge, this is the first report showing that an IGF-1 inhibitor was able to markedly increase the response of tumour cells to ionizing radiation. These results suggest that Tyrphostin AG 1024 could be used as a potential therapeutic agent in combination with irradiation. http://www.bjcancer.com © 2001 Cancer Research Campaign

Real-time detection of insulin-like growth factor-1 stimulation of the MAC-T bovine mammary epithelial cell line.

Binding of growth factors by cell-surface receptors is an essential means by which cells regulate normal tissue growth and differentiation. Exposure to growth factors is often transient, and our goal was to determine whether short-term exposure to insulin-like growth factor-1 (IGF-1) would lead to activation, assayed as cell proliferation, of mammary epithelial cells. The MAC-T cell line is an immortalized bovine mammary epithelial cell line, chosen as our model mammary cell line because of its known sensitivity to IGF-1. Using the Cytosensor Microphysiometer System, a biosensor capable of measuring extracellular acidification, we were able to measure activation of the cells owing to IGF-1 addition in real time and found that peak acidification occurred in only 14 min. We show that this rapid response to IGF-1 is dose dependent and specific for IGF-1. A significant increase in [3H]thymidine incorporation by cells after a similar short-term exposure to IGF-1 suggests that the measured increase in extracellular acidification following IGF-1 addition is physiologically relevant. This technology offers a new, novel, and rapid means for the study of IGF-1 activity, as well as the screening of IGF-1 inhibitors, in mammary epithelial cells.