Showing papers on "Growth factor receptor inhibitor published in 2002"
TL;DR: Recognized as the single most important angiogenic cytokine, VEGF-A has a central role in tumor biology and will likely have an important role in future approaches designed to evaluate patient prognosis and may also become an important target for cancer therapy.
Abstract: Vascular endothelial growth factor A (VEGF-A), the founding member of the vascular permeability factor (VPF)/VEGF family of proteins, is an important angiogenic cytokine with critical roles in tumor angiogenesis. This article reviews the literature with regard to VEGF-A's multiple functions, the mechanisms by which it induces angiogenesis, and its current and projected roles in clinical oncology. VEGF-A is a multifunctional cytokine that is widely expressed by tumor cells and that acts through receptors (VEGFR-1, VEGFR-2, and neuropilin) that are expressed on vascular endothelium and on some other cells. It increases microvascular permeability, induces endothelial cell migration and division, reprograms gene expression, promotes endothelial cell survival, prevents senescence, and induces angiogenesis. Recently, VEGF-A has also been shown to induce lymphangiogenesis. Measurements of circulating levels of VEGF-A may have value in estimating prognosis, and VEGF-A and its receptors are potential targets for therapy. Recognized as the single most important angiogenic cytokine, VEGF-A has a central role in tumor biology and will likely have an important role in future approaches designed to evaluate patient prognosis. It may also become an important target for cancer therapy.
1,537 citations
TL;DR: It is reported that growth factor withdrawal results in the loss of surface transporters for not only glucose but also amino acids, low-density lipoprotein, and iron, which creates a catabolic state characterized by atrophy and a decline in the mitochondrial membrane potential.
Abstract: In multicellular organisms, constituent cells depend on extracellular signals for growth, proliferation, and survival. When cells are withdrawn from growth factors, they undergo apoptosis. Expression of constitutively active forms of the serine/threonine kinase Akt/PKB can prevent apoptosis upon growth factor withdrawal. Akt-mediated survival depends in part on the maintenance of glucose metabolism, suggesting that reduced glucose utilization contributes to growth factor withdrawal-induced death. However, it is unclear how restricting access to extracellular glucose alone would lead to the metabolic collapse observed after growth factor withdrawal. We report herein that growth factor withdrawal results in the loss of surface transporters for not only glucose but also amino acids, low-density lipoprotein, and iron. This coordinated decline in transporters and receptors for extracellular molecules creates a catabolic state characterized by atrophy and a decline in the mitochondrial membrane potential. Activated forms of Akt maintained these transporters on the cell surface in the absence of growth factor through an mTOR-dependent mechanism. The mTOR inhibitor rapamycin diminished Akt-mediated increases in cell size, mitochondrial membrane potential, and cell survival. These results suggest that growth factors control cellular growth and survival by regulating cellular access to extracellular nutrients in part by modulating the activity of Akt and mTOR.
577 citations
TL;DR: The rationale for EGFR-targeted approaches to cancer treatment is apparent and now well established, and there is increasing evidence that they may represent a significant contribution to cancer therapy.
Abstract: There is a need for new, selective anticancer agents that differentiate between malignant and nonmalignant cells. The benefits of such agents would include a higher therapeutic index and lower toxicity than conventional therapies. Although expressed in nonmalignant cells, the epidermal growth factor receptor (EGFR) is highly expressed in a variety of tumors, and its expression correlates with poor response to treatment, disease progression, and poor survival. Evidence for a role for the EGFR in the inhibition and pathogenesis of various cancers has led to the rational design and development of agents that selectively target this receptor. Activation of the EGFR signaling pathway in cancer cells has been linked with increased cell proliferation, angiogenesis, and metastasis, and decreased apoptosis. Preclinical data show that anti-EGFR therapies can inhibit these effects in vitro and in vivo. In addition, preclinical data confirm that many such agents have the potential to increase the effectiveness of current cytotoxic agents. Following accelerated drug development programs, phase III trials are now under way for a number of EGFR-targeted therapies, including the monoclonal antibody IMC-C225 and the EGFR-tyrosine kinase inhibitors ZD1839 (Iressa) and OSI-774. Thus, the rationale for EGFR-targeted approaches to cancer treatment is apparent and now well established, and there is increasing evidence that they may represent a significant contribution to cancer therapy.
510 citations
TL;DR: Until EGFR-based assays predictive of a response to receptor-targeted therapies are available, there is no clear justification for stratifying patients by EGFR status or excluding patients with low EGFR levels from trials with ZD1839 or other EGFR inhibitors.
Abstract: The epidermal growth factor receptor (EGFR) is a rational target for antitumor strategies. EGFR signaling causes increased proliferation, decreased apoptosis, and enhanced tumor cell motility and neo-angiogenesis. The EGFR is expressed or highly expressed in a variety of human tumors of epithelial origin. ZD1839 (Iressa) is an orally active, selective EGFR tyrosine kinase inhibitor, which blocks signal transduction pathways implicated in proliferation and survival of cancer cells. The lack of a consistent method of evaluating levels of EGFR has caused a disparity in reports of the EGFR as a prognostic factor; however, for some tumors, EGFR is a strong prognostic indicator associated with more aggressive disease and reduced survival. So far, no clear association between EGFR levels and response to EGFR-targeted agents has been found. Preclinical studies with ZD1839 have noted a relationship between the two in some cases, but not others. EGFR signaling may be increased by a number of mechanisms in addition to high expression levels of EGFR, including receptor mutations, heterodimerization with other members of this receptor family such as HER2 (erbB2), increased expression of (autocrine/ paracrine) ligands, and alterations in molecules that control receptor signaling output. Each of these components could be assessed to give an indication of the magnitude of EGFR signal amplification. Evaluation of signaling components downstream from EGFR should provide information on the activation of the EGFR pathway. Until EGFR-based assays predictive of a response to receptor-targeted therapies are available, there is no clear justification for stratifying patients by EGFR status or excluding patients with low EGFR levels from trials with ZD1839 or other EGFR inhibitors.
472 citations
Journal Article•
439 citations
TL;DR: This review summarizes some new aspects of peptide and steroid hormone signaling in the rodent ovary that appear to regulate cumulus expansion and other aspects relating to ovarian embryogenesis and possibly ovulation and luteinization.
Abstract: The interactions of peptide and steroid hormone signaling cascades in the ovary are critical for follicular growth, ovulation, and luteinization. Although the pituitary gonadotropins follicle-stimulating hormone (FSH) and luteinizing hormone (LH) play key regulatory roles, their actions are also dependent on other peptide signaling pathways, including those stimulated by insulin-like growth factor-1 (IGF-1), transforming growth factor-beta (TGF-beta) family members (e.g., inhibin, activin, growth differentiation factor-9, bone morphogenic proteins), fibroblast growth factor, and Wnts (via Frizzled receptors). Each of these factors is expressed and acts in a cell-specific manner at defined stages of follicular growth. IGF-1, estrogen, and FSH comprise one major regulatory system. The Wnt/Frizzled pathways define other aspects relating to ovarian embryogenesis and possibly ovulation and luteinization. Likewise, the steroid receptors as well as orphan nuclear receptors and their ligands impact ovarian cell function. The importance of these multiple signaling cascades has been documented by targeted deletion of specific genes. For example, mice null for the LH-induced genes progesterone receptor (PR) and cyclo-oxygenase-2 (COX-2) fail to ovulate. Whereas PR appears to regulate the induction of novel proteases, COX-2 appears to regulate cumulus expansion. This review summarizes some new aspects of peptide and steroid hormone signaling in the rodent ovary.
417 citations
TL;DR: It is demonstrated that overproduction of mucus is a direct result of the activation of mucin gene expression by Gram-positive bacteria.
Abstract: In the lungs of cystic fibrosis patients, overproduction of mucus leads to morbidity and mortality by obstructing airflow and shielding bacteria from antibiotics. Here we demonstrate that overproduction of mucus is a direct result of the activation of mucin gene expression by Gram-positive bacteria. Bacterial lipoteichoic acid activates the platelet-activating factor receptor, which is G protein-coupled. This results in activation of a disintegrin and metalloproteinase (ADAM10), kuzbanian, cleavage of pro heparin-binding epidermal growth factor and activation of the epidermal growth factor receptor. Unlike responses in macrophages, the epithelial-cell response to lipoteichoic acid does not require Toll-like receptor 2 or 4.
348 citations
TL;DR: MUC2 and MUC5AC are two target genes of EGFR ligands in lung cancer cells, and up-regulation of these two genes goes through concomitant activation of the EGFR/Ras/Raf/Extracellular Signal-regulated Kinase-signaling pathway and Sp1 binding to their promoters.
262 citations
TL;DR: The combination of anti-VEGF-R and anti-EGF-R therapies was effective in inhibiting gastric cancer growth and support the hypothesis that inhibiting multiple biological pathways that mediate tumour growth may be an effective therapeutic strategy.
257 citations
TL;DR: The discovery of a cell survival mechanism by which Met, a growth factor receptor tyrosine kinase, directly binds to and sequesters the death receptor Fas in hepatocytes, thus inhibiting Fas activation and apoptosis is reported.
221 citations
TL;DR: It is demonstrated that blockade of the EGF receptor by a new drug in phase III clinical trails for cancer, ZD1839, potently induces apoptosis in mammary epithelial cell lines and primary cultures, as well as in a primary pleural effusion from a breast cancer patient.
Journal Article•
TL;DR: It is proposed that PlGF-2 contributes to tumor angiogenesis by providing increased survival function to endothelial cells and macrophages by inducing survival gene expression and inhibits apoptosis in vitro.
Abstract: The vascular endothelial growth factor (VEGF)-related factor, placental growth factor (PlGF),has been shown recently to play an important role in pathological VEGF-driven angiogenesisIn this study, we examine the effects of mPlGF/PlGF-2 overexpression in tumors grown from glioma cells containing a tetracycline-regulated mPlGF cDNA Overexpression of mPlGF leads to increased tumor growth and vascular survival When tetracycline is used to abruptly withdraw mPlGF overexpression, we see increased apoptosis in both vascular cells and macrophages In addition, PlGF-2 induces survival gene expression and inhibits apoptosis in vitro Thus, we propose that PlGF-2 contributes to tumor angiogenesis by providing increased survival function to endothelial cells and macrophages
Patent•
17 May 2002TL;DR: In this article, DNA isolates coding for a vascular endothelial cell growth factor may be used to produce the protein via recombinant expression systems, which is useful therapeutically to treat conditions in which a selective action on the vascular endothel cells, in the absence of excessive connective tissue proliferation, is desirable.
Abstract: DNA isolates coding for a vascular endothelial cell growth factor may be used to produce the protein via recombinant expression systems. Such protein is useful therapeutically to treat conditions in which a selective action on the vascular endothelial cells, in the absence of excessive connective tissue proliferation, is desirable.
Journal Article•
TL;DR: It is demonstrated that PI3K-Akt signaling promotes SCLC growth, survival, and chemotherapy resistance, and selective inhibitors of PI3k or Akt could potentially be useful as novel therapeutic agents in the treatment of SclC.
Abstract: A promising therapeutic alternative to inhibition of growth factor receptors is the inhibition of downstream signal transduction pathways. Such an approach may be especially important in tumors that can use signals from multiple growth factor receptors for growth and survival. Both stem cell factor (SCF) and insulin-like growth factor (IGF)-I, components of prominent small cell lung cancer (SCLC) autocrine loops, as well as FCS, can potently activate phosphatidylinositol 3-kinase (PI3K)-Akt signaling, albeit with different kinetics. SCF-induced PI3K-Akt activation occurs rapidly but fades within 60 min; IGF-I and FCS-induced activation persists for at least 6 h. SCF and IGF-I-mediated growth was potently inhibited by LY294002 in proportion to its ability to inhibit phosphatidylinositol 3-kinase (PI3K)-Akt signaling. A panel of six SCLC cell lines grown in 10% FCS was also very sensitive to LY294002, with average IC50 and LD50 of 5 and 25 μm, respectively. These drug concentrations suppressed the growth of the MRC-5 pulmonary fibroblast cell line and primary bronchial epithelial cells but did not induce significant cell death. Because LY294002 can also inhibit PI3K-related enzymes, we confirmed the role of the PI3K-Akt pathway in SCLC using doxycycline-regulated expression of a dominant-negative (kinase dead) and a constitutively active (CA; myristolated) Akt allele. Expression of dominant-negative Akt, which could only be achieved at relatively low levels, completely inhibited growth in the absence of exogenous growth factors and inhibited SCF-mediated growth but had no effect on IGF-I-mediated growth at the expression levels attained. Expression of CA Akt markedly augmented growth in the absence of exogenous growth factors but had minimal effect on growth in the presence of saturating concentrations SCF or IGF-I. Because PI3K-Akt signaling is known to promote survival under apoptotic stresses, we determined the effect of this pathway on SCLC sensitivity to etoposide. LY294002 potentiated the effect of low concentrations of etoposide in inhibiting growth and inducing apoptosis. The effect of low concentrations of LY294002 could largely be reversed by expression of CA Akt, suggesting that it was mediated by inhibition of Akt signaling. Expression of CA Akt by itself also induced resistance to etoposide-mediated apoptosis. Taken together, these data demonstrate that PI3K-Akt signaling promotes SCLC growth, survival, and chemotherapy resistance. Therefore, selective inhibitors of PI3K or Akt could potentially be useful as novel therapeutic agents in the treatment of SCLC.
TL;DR: Modulation of cytokines and growth factors by 1alpha,25(OH)(2)D(3) during bone remodeling plays an important role in the coupling of osteoblastic bone formation with osteoclastic resorption to maintain bone mass.
Abstract: Distinct from its classic functions in the regulation of calcium and phosphorus metabolism as a systemic hormone, 1alpha,25-dihydroxyvitamin D(3) [1alpha,25(OH)(2)D(3)] is involved in the local control and regulation of cellular growth and differentiation in various tissues, including epidermis (keratinocytes) and bone (osteoblasts and osteoclasts). In this review, the impact of 1alpha,25(OH)(2)D(3) on growth factor/cytokine synthesis and signaling is discussed, particularly as it pertains to bone cells and keratinocytes. 1alpha,25(OH)(2)D(3) not only regulates growth factor/cytokine synthesis but may also alter growth factor signaling. Recently discovered examples for such interactions are the interactions between the vitamin D receptor and the mothers against decapentaplegic-related proteins that function downstream of TGFbeta receptors. Inhibitory effects of 1alpha,25(OH)(2)D(3) on keratinocytes through TGFbeta activation and IL-1alpha, IL-6, and IL-8 suppression may provide a rationale for its beneficial effects in the treatment of hyperproliferative skin disorders, whereas stimulatory effects through the epidermal growth factor-related family members and platelet-derived growth factor may be operative in its beneficial effects in skin atrophy and wound healing. Modulation of cytokines and growth factors by 1alpha,25(OH)(2)D(3) during bone remodeling plays an important role in the coupling of osteoblastic bone formation with osteoclastic resorption to maintain bone mass.
Journal Article•
TL;DR: These studies demonstrate that the IGF ligand-receptor system plays an important role in multiple mechanisms that mediate human colon cancer growth including regulation of VEGF and angiogenesis.
Abstract: Purpose and Experimental Design: Insulin-like growth factors (IGFs) I and II and their principle receptor, IGF-I receptor (IGF-IR), are frequently expressed in human colon cancers and play a role in preventing apoptosis, enhancing cell proliferation, and inducing expression of vascular endothelial growth factor (VEGF). To elucidate the in vitro and in vivo effects of IGF-IR in human colon cancer growth and angiogenesis, HT29 cells were transfected with a truncated dominant-negative (DN) form of IGF-IR or vector alone. Results: IGF-I increased VEGF expression in parental and vector-transfected cells, whereas IGF-I induction of VEGF mRNA and protein was abrogated in IGF-IR DN cells. The IGF-IR DN cells demonstrated inhibited growth in both monolayer culture and soft agar ( P P P Conclusions: These studies demonstrate that the IGF ligand-receptor system plays an important role in multiple mechanisms that mediate human colon cancer growth including regulation of VEGF and angiogenesis.
TL;DR: It is proposed that, in addition to its role as an angiogenic factor, vascular endothelial growth factor (VEGF) can act as a survival factor for tumour cells protecting them from apoptosis, and anti-VEGF strategies may overcome therapy- induced tumour cell resistance.
Abstract: Angiogenesis is central to both the growth and metastasis of solid tumours. Anti-angiogenic strategies result in blood vessel regression accompanied by tumour cell apoptosis. Radiotherapy and many chemotherapeutic agents kill tumours by inducing apoptotic cell death. We propose that, in addition to its role as an angiogenic factor, vascular endothelial growth factor (VEGF) can act as a survival factor for tumour cells protecting them from apoptosis. Thus anti-angiogenics, in particular those directed against VEGF, have multiple anti-tumour effects. We suggest that anti-VEGF strategies prevent vessel growth and block a tumour cell survival factor, VEGF, rendering tumour cells more sensitive to chemotherapy and radiotherapy. In addition, as chemotherapy and radiotherapy have been shown to increase VEGF expression, anti-VEGF strategies may overcome therapy- induced tumour cell resistance. BioEssays 24:280–283, 2002. © 2002 Wiley Periodicals, Inc.; DOI 10.1002/bies.10043
TL;DR: It is shown that MMP9-expressing tumor-associated macrophages play a key role in prepping premetastatic sites for eventual malignant cell growth in a manner dependent upon vascular endothelial growth factor receptor-1 (VEGFR-1).
TL;DR: The inactivation and loss of expression of p16, p53, and p21, and the expression of several apoptotic genes, such as bax and bcl-2, have not been found to be of any prognostic significance, however, theexpression of wild type p53 may predict responsiveness to chemotherapy.
Abstract: Pancreatic cancer has a very poor prognosis and is a common cause of cancer death in the Western world. Certain genetic alterations may be important in the prognosis of pancreatic cancer. Activation mutations in the K- ras oncogene occur in around 90% of pancreatic cancers, and the overexpression of growth factors epidermal growth factor (EGF), transforming growth factor (TGF)alpha, TGFbetas 1-3, acidic fibroblast growth factor (aFGF), basic FGF (bFGF), and growth factor receptors c-erbB-2 and -3 and TGFRbetas 1-3 is common. High mutation levels of cell cycle control genes such as p53, p16, p21, SMAD4, and cyclin D1 are found, and there is abnormal expression of apoptotic genes, such as bcl-2, bcl-XL, and bax. The expression of several of these growth factors and their receptors has been found to be associated with poorly differentiated tumors of an advanced stage and decreased survival. However, the inactivation and loss of expression of p16, p53, and p21, and the expression of several apoptotic genes, such as bax and bcl-2, have not been found to be of any prognostic significance. The expression of wild type p53, however, may predict responsiveness to chemotherapy. TGFbeta1 expression has been shown to be associated with longer survival in patients with pancreatic cancer. Two studies (including our own) have found bcl-XL expression to be significantly associated with poor survival. These and newer molecular markers may prove to be important in the choice of future therapies for pancreatic cancer.
TL;DR: Preclinical studies have shown that ZD1839, an oral anilinoquinazoline, targets the epidermal growth factor receptor-associated tyrosine kinase, reversibly inhibiting critical downstream signaling and resulting in cancer cell growth arrest.
TL;DR: In this paper, the Notch family of receptors and ligands plays an important role in cell fate determination, vasculogenesis, and organogenesis in adult vascular smooth muscle cells (VSMCs).
Abstract: The Notch family of receptors and ligands plays an important role in cell fate determination, vasculogenesis, and organogenesis. Mutations of the Notch-3 receptor result in an arteriopathy that predisposes to early-onset stroke. However, the functional role of the Notch signaling pathway in adult vascular smooth muscle cells (VSMCs) is poorly characterized. This study documents that the Notch-3 receptor, the ligand Jagged-1, and the downstream transcription factor, HESR-1, are expressed in the normal adult rat carotid artery, and that this expression is modulated after vascular injury. In cultured VSMCs, both angiotensin II and platelet-derived growth factor (PDGF) markedly downregulated Notch-3 and Jagged-1 through ERK-dependent signaling mechanisms and prevented the glycosylation of Jagged-1. The downregulation of Jagged-1 and Notch-3 was associated with a decrease in CBF-1-mediated gene transcription activation and a fall in the mRNA levels of the downstream target transcription factor HESR-1. To test the hypothesis that the Notch pathway was coupled to growth regulation, we generated VSMC lines overexpressing the constitutively active form of Notch-3 (A7r5-N3IC). These cells exhibited a biphasic growth behavior in which the growth rate was retarded during the subconfluent phase and failed to decelerate at postconfluence. The lack of cell-cycle arrest in postconfluent A7r5-N3IC was associated with an attenuated upregulation of the cell-cycle inhibitor p27(kip) relative to control cells. This study documents the regulation of the Jagged-1 and Notch-3 genes in VSMCs by growth factor stimulation as well as a role for Notch-3 as a determinant of VSMC growth.
TL;DR: It is believed that gangliosides do not act independently of many well-established mechanisms of receptor regulation, such as clathrin-coated pit internalization and ubiquitination, but that they contribute to these functions and to signal transduction pathways.
Abstract: Since their discovery in the 1940s, gangliosides have been associated with a number of biological processes, such as growth, differentiation, and toxin uptake. Hypotheses about regulation of these processes by gangliosides are based on indirect observations and lack a clear definition of their mechanisms within the cell. The first insights were provided when a reduction in cell proliferation in the presence of gangliosides was attributed to inhibition of the epidermal growth factor receptor (EGFR). Since that initial finding, most, if not all, growth factor receptors have been described as regulated by gangliosides. In this review, we describe the effects of gangliosides on growth factor receptors, beginning with a list of known effects of gangliosides on growth factor receptors; we then present three models based on fibroblast growth factor (FGFR), platelet-derived growth factor receptor (PDGFR), and EGFR. We focus first on ganglioside modulation of ligand binding; second, we discuss ganglioside regulation of receptor dimerization; and third, we describe a model that implicates gangliosides with receptor activation state and subcellular localization. The methodology used to develop the three models may be extended to all growth factor receptors, bearing in mind that the three models may not be mutually exclusive. We believe that gangliosides do not act independently of many well-established mechanisms of receptor regulation, such as clathrin-coated pit internalization and ubiquitination, but that gangliosides contribute to these functions and to signal transduction pathways. We hypothesize a role for the diverse structures of gangliosides in biology through the organization of the plasma membrane into lipid raft microdomains of unique ganglioside composition, which directly affect the signal duration and membrane localization of the growth factor receptor.
TL;DR: The ability of mast cells to express and/or secrete several growth factors of the fibroblast growth factor family as well as heparin-binding epidermal growth factor directly or indirectly via stimulation of fibroblasts is demonstrated, underlining the potentially pivotal role of these cells during human tissue repair and homeostasis.
TL;DR: In vivo, ABX-EGF not only blocks formation of human epidermoid carcinoma A431 xenografts in athymic mice, but also mediates therapeutic elimination of established tumors and acts cooperatively with chemotherapeutics in mediating tumor regression.
TL;DR: An immune-based antiangiogenic strategy that is based on the generation of T lymphocytes that possess a killing specificity for cells expressing vascular endothelial growth factor receptors (VEGFRs), which may prove to be a powerful means for controlling tumor growth.
Abstract: The demonstration that angiogenesis is required for the growth of solid tumors has fueled an intense interest in the development of new therapeutic strategies that target the tumor vasculature. Here we report the development of an immune-based antiangiogenic strategy that is based on the generation of T lymphocytes that possess a killing specificity for cells expressing vascular endothelial growth factor receptors (VEGFRs). To target VEGFR-expressing cells, recombinant retroviral vectors were generated that encoded a chimeric T cell receptor comprised of VEGF sequences linked to intracellular signaling sequences derived from the ζ chain of the T cell receptor. After transduction of primary murine CD8 lymphocytes by such vectors, the transduced cells were shown to possess an efficient killing specificity for cells expressing the VEGF receptor, Flk-1, as measured by in vitro cytotoxicity assays. After adoptive transfer into tumor-bearing mice, the genetically modified cytotoxic T lymphocytes strongly inhibited the growth of a variety of syngeneic murine tumors and human tumor xenografts. An increased effect on in vivo tumor growth inhibition was seen when this therapy was combined with the systemic administration of TNP-470, a conventional angiogenesis inhibitor. The utilization of the immune system to target angiogenic markers expressed on tumor vasculature may prove to be a powerful means for controlling tumor growth.
TL;DR: Results from Phase I – II trials in advanced cancer demonstrate that anti-epidermal growth factor receptor agents have an acceptable tolerability and an interesting clinical activity in patients with a variety of tumour types.
Abstract: The epidermal growth factor receptor is a cell membrane growth factor receptor that plays a key role in cancer development and progression. Epidermal growth factor receptor-activated signalling pathways control cell proliferation, apoptosis, angiogenesis and metastatic spread in the majority of human epithelial cancers. Targeting the epidermal growth factor receptor represents a valuable molecular approach to cancer therapy. Promising strategies in clinical development include monoclonal antibodies which block ligand binding and small molecule inhibitors of the tyrosine kinase enzymatic activity which prevent epidermal growth factor receptor autophosphorylation and propagation of downstream intracellular signals. Several anti-epidermal growth factor receptor agents are in clinical development for cancer therapy. Among these, IMC-225 (cetuximab), a chimeric human-mouse monoclonal IgG1 antibody, OSI-774 (Tarceva) and ZD1839 (Iressa), two small molecule epidermal growth factor receptor-selective tyrosine kinase inhibitors, are currently in Phase II and III development as single agents or in combination with conventional therapies, such as radiotherapy or chemotherapy. Results from Phase I - II trials in advanced cancer demonstrate that these drugs have an acceptable tolerability and an interesting clinical activity in patients with a variety of tumour types.
Journal Article•
TL;DR: Observations support the concept that simultaneously co-targeting tyrosine kinase receptors may be therapeutically useful, and provide a specific rationale for combining IGF-1R and HER2/erbB2 targeting strategies in anti-neoplastic approaches.
Abstract: BACKGROUND The humanized anti-HER2 monoclonal antibody trastuzumab (Herceptin) is useful in the treatment of ErbB2-overexpressing breast cancers, but its efficiency is limited because development of resistance is common. In order to study the possibility of improving the efficacy of therapies directed against HER2/erbB2, we investigated the effects of co-targeting this receptor and the insulin-like growth factor 1 receptor (IGF-1R), a widely-expressed protein tyrosine kinase with important roles in suppression of apoptosis and stimulation of proliferation. MATERIAL/METHODS The experimental strategy involved combining trastuzumab treatment and reduction of IGF-1R signaling through incremental heat-induced expression of the dominant-negative IGF-1 receptor 486/STOP under the control of the heat-sensitive Drosophila HSP70 promoter, in HER2/erbB2-overexpressing MCF7her18 breast cancer cells. RESULTS Isobologram analysis of combinatorial treatment data revealed a strong synergistic interaction between trastuzumab treatment and the induction of the dominant-negative IGF-1R expression, resulting in potentiation of growth inhibition in transfected cancer cells. CONCLUSIONS These observations support the concept that simultaneously co-targeting tyrosine kinase receptors may be therapeutically useful, and provide a specific rationale for combining IGF-1R and HER2/erbB2 targeting strategies in anti-neoplastic approaches.
TL;DR: The role of IGFs and IGFBPs in growth, tumorigenesis and diabetes are examined, and treatment modalities for each disease involving the GH-IGF-igFBP axis are discussed, including discussion of current in vitro and in vivo investigations in this field.
TL;DR: A signaling pathway for IGFBP-3 is defined from a cell surface receptor to nuclear transcriptional activity, requiring TGF-βRII but not dependent on the nuclear translocation of IGF BP-3.
TL;DR: It is suggested that overexpression of EF-1α results in selective resistance to apoptosis induced by growth factor withdrawal and ER stress, and not from nuclear damage or death receptor signaling.
Abstract: To identify genes that contribute to apoptotic resistance, IL-3 dependent hematopoietic cells were transfected with a cDNA expression library and subjected to growth factor withdrawal. Transfected cells were enriched for survivors over two successive rounds of IL-3 withdrawal and reconstitution, resulting in the identification of a full-length elongation factor 1 alpha (EF-1alpha) cDNA. Ectopic EF-1alpha expression conferred protection from growth factor withdrawal and agents that induce endoplasmic reticulum stress, but not from nuclear damage or death receptor signaling. Overexpression of EF-1alpha did not lead to growth factor independent cell proliferation or global alterations in protein levels or rates of synthesis. These findings suggest that overexpression of EF-1alpha results in selective resistance to apoptosis induced by growth factor withdrawal and ER stress.