Effects of insulin-like growth factor-1 on B-cell precursor acute lymphoblastic leukemia

Signaling Pathways of the Insulin-like Growth Factor Binding Proteins

The 6 high-affinity insulin-like growth factor binding proteins (IGFBPs) are multifunctional proteins that modulate cell signaling through multiple pathways. Their canonical function at the cellular level is to impede access of insulin-like growth factor (IGF)-1 and IGF-2 to their principal receptor IGF1R, but IGFBPs can also inhibit, or sometimes enhance, IGF1R signaling either through their own post-translational modifications, such as phosphorylation or limited proteolysis, or by their interactions with other regulatory proteins. Beyond the regulation of IGF1R activity, IGFBPs have been shown to modulate cell survival, migration, metabolism, and other functions through mechanisms that do not appear to involve the IGF-IGF1R system. This is achieved by interacting directly or functionally with integrins, transforming growth factor β family receptors, and other cell-surface proteins as well as intracellular ligands that are intermediates in a wide range of pathways. Within the nucleus, IGFBPs can regulate the diverse range of functions of class II nuclear hormone receptors and have roles in both cell senescence and DNA damage repair by the nonhomologous end-joining pathway, thus potentially modifying the efficacy of certain cancer therapeutics. They also modulate some immune functions and may have a role in autoimmune conditions such as rheumatoid arthritis. IGFBPs have been proposed as attractive therapeutic targets, but their ubiquity in the circulation and at the cellular level raises many challenges. By understanding the diversity of regulatory pathways with which IGFBPs interact, there may still be therapeutic opportunities based on modulation of IGFBP-dependent signaling.

Maternal obesity and acute lymphoblastic leukemia risk in offspring: A summary of trends, epidemiological evidence, and possible biological mechanisms

Acute lymphoblastic leukemia, a heterogenous malignancy characterized by uncontrolled proliferation of lymphoid progenitors and generally initiated in utero, is the most common pediatric cancer. Although incidence of ALL has been steadily increasing in recent decades, no clear reason for this trend has been identified. Rising concurrently with ALL incidence, increasing maternal obesity rates may be partially contributing to increasing ALL prevelance. Epidemiological studies, including a recent meta-analysis, have found an association between maternal obesity and leukemogenesis in offspring, although mechanisms underlying this association remain unknown. Therefore, the purpose of this review is to propose possible mechanisms connecting maternal obesity to ALL risk in offspring, including changes to fetal/neonatal epigenetics, altered insulin-like growth factor profiles and insulin resistance, modified adipokine production and secretion, changes to immune cell populations, and impacts on birthweight and childhood obesity/adiposity. We describe how each proposed mechanism is biologically plausible due to their connection with maternal obesity, presence in neonatal and/or fetal tissue, observation in pediatric ALL patients at diagnosis, and association with leukemogenesis, A description of ALL and maternal obesity trends, a summary of epidemiological evidence, a discussion of the pathway from intrauterine environment to subsequent malignancy, and propositions for future directions are also presented.

Physiologic IGFBP7 levels prolong IGF1R activation in acute lymphoblastic leukemia

Insulin and insulin-like growth factors (IGFs) are mitogenic and prosurvival factors to many different cell types, including acute lymphoblastic leukemia (ALL). Circulating IGFs are bound by IGF binding proteins (IGFBPs) that regulate their action. IGFBP7 is an IGFBP-related protein (IGFBP-rP) that in contrast to other IGFBPs/IGFBP-rPs features higher affinity for insulin than IGFs and was shown to bind the IGF1 receptor (IGF1R) as well. The role of IGFBP7 in cancer is controversial: on some tumors, it functions as an oncogene, whereas in others, it functions as a tumor suppressor. In childhood ALL, higher IGFBP7 expression levels were associated with worse prognosis. Here we show that IGFBP7 exerts mitogenic and prosurvival autocrine effects on ALL cells that were dependent on insulin/IGF. IGFBP7 knockdown or antibody-mediated neutralization resulted in significant attenuation of ALL cell viability in vitro and leukemia progression in vivo. IGFBP7 was shown to prolong the surface retention of the IGF1R under insulin/IGF1 stimulation, resulting in sustained IGF1R, insulin receptor substrate 1 (IRS-1), protein kinase B (AKT), and extracellular signal-regulated kinase (ERK) phosphorylation. Conversely, the insulin receptor was readily internalized and dephosphorylated on insulin stimulation, despite IGFBP7 addition. The affinity of homodimeric IGF1R for insulin is reportedly >100 times lower than for IGF1. In the presence of IGFBP7, however, 25 ng/mL insulin resulted in IGF1R activation levels equivalent to that of 5 ng/mL IGF1. In conclusion, IGFBP7 plays an oncogenic role in ALL by promoting the perdurance of IGF1R at the cell surface, prolonging insulin/IGF stimulation. Preclinical data demonstrate that IGFBP7 is a valid target for antibody-based therapeutic interventions in ALL.

Insulin-like growth factor-1 short-period therapy stimulates bone marrow cells in obese swiss mice

Bone marrow cells (BMCs) from obese Swiss mice fed with Western diet show mitochondrial dysfunction. Obesity interferes with BMCs disrupting energetic metabolism, stimulating apoptosis, and reducing cell proliferation since adipose tissue releases inflammatory adipokines into the medullar microenvironment. These changes lead to reduction of BMC differentiation capacity and hematopoiesis impairment, a process responsible for blood cell continuous production through hematopoietic stem cells (HSCs). This work aimed to analyze the effects of IGF-1 therapy on BMC viability in Western diet-induced obesity, in vivo. We observed that after only 1 week of treatment, obese Swiss mice presented reduced body weight and visceral fat and increased mitochondrial oxidative capacity and coupling, indicating mitochondrial function improvement. In addition, IGF-1 was able to reduce apoptosis of total BMCs, stem cell subpopulations (hematopoietic and mesenchymal), and leukocytes, restoring all progenitor hematopoietic lineages. The treatment also contributed to increase proliferative capacity of hematopoietic stem cells and leukocytes, keeping the hematopoietic and immune systems balanced. Therefore, we conclude that IGF-1 short period therapy improved BMC survival, proliferation, and differentiation capacity in obese Swiss mice.

Increased risk of leukaemia in children with Down syndrome: a somatic evolutionary view

Children show a higher incidence of leukaemia compared with young adolescents, yet their cells are less damaged because of their young age. Children with Down syndrome (DS) have an even higher risk of developing leukaemia during the first years of life. The presence of a constitutive trisomy of chromosome 21 (T21) in DS acts as a genetic driver for leukaemia development, however, additional oncogenic mutations are required. Therefore, T21 provides the opportunity to better understand leukaemogenesis in children. Here, we describe the increased risk of leukaemia in DS during childhood from a somatic evolutionary view. According to this idea, cancer is caused by a variation in inheritable phenotypes within cell populations that are subjected to selective forces within the tissue context. We propose a model in which the increased risk of leukaemia in DS children derives from higher rates of mutation accumulation, already present during fetal development, which is further enhanced by changes in selection dynamics within the fetal liver niche. This model could possibly be used to understand the rate-limiting steps of leukaemogenesis early in life.

IGF family effects on development, stability, and treatment of hematological malignancies

Multiple factors, including growth factors, are shown to be culprits of cancer outset and persistence. Among growth factors, insulin-like growth factors (IGFs) family are of more importance in the prognosis of blood malignancies. After binding to their corresponding receptor, IGFs initiate PI3K/AKT signaling pathway and increase the translation of intracellular proteins, such as cell division-related proteins. They also stimulate the transcription of cell division-related genes using the Ras-GTP pathway. In addition to organs such as the liver, IGFs are secreted by tumor cells and can cause growth and proliferation of self or tumor cells via autocrine and paracrine methods. Current studies indicate that decreasing the effects of IGF by blocking them, their receptors, or PI3K/AKT pathway using various drugs could help to suppress the division of tumor cells. Here, we delineate the role of the IGF family in hematologic malignancies and their potential mechanisms.

Gene expression and prognosis of insulin‑like growth factor‑binding protein family members in non‑small cell lung cancer

Lung cancer is the leading cause of cancer mortality worldwide. Approximately 85% of all lung cancer cases are classified as non-small cell lung cancer (NSCLC). Currently, there is no standard method to predict the survival of patients with NSCLC. Insulin-like growth factor-binding proteins (IGFBPs) function as modulators of IGF signaling and are attracting increasing attention for their role in NSCLC. However, the prognostic values of individual IGFBPs in NSCLC, particularly at the mRNA level, remain unknown. In the present study, the distinct expression patterns and prognostic values of IGFBP family members in patients with NSCLC through bioinformatics analysis were reported using a series of databases, including Gene Expression Profiling Interactive Analysis, Kaplan-Meier Plotter, cBioPortal, GeneMANIA, and the Database for Annotation, Visualization and Integrated Discovery. In patients with NSCLC, IGFBP2 and IGFBP3 were significantly upregulated, while IGFBP6 was downregulated. High IGFBP1/2/4 expression was correlated with poor overall survival (OS) in all NSCLC types, especially adenocarcinoma; however, high IGFBP2/5 expression was significantly correlated with favorable OS only in patients with squamous cell carcinoma. In addition, aberrant IGFBP1/2/3/4/5 mRNA levels were associated with the prognosis of subsets of NSCLC with different clinicopathological features. These results indicated that various IGFBPs can serve as useful prognostic biomarkers and as potential targets for NSCLC therapies.

The prognostic values of insulin-like growth factor binding protein in breast cancer

Insulin-like growth factor binding proteins (IGFBPs) are a family of proteins binding to insulin-like growth factors, generally consisting 6 high-affinity IGFBPs, namely IGFBP1 through IGFBP6. IGFBP family members have been indicated to be involved in the development and progression of tumors and may be useful prognostic biomarkers in various malignancies. However, the prognostic role of individual IGFBPs, especially at the mRNA level in breast cancer patients remains elusive.We accessed the prognostic roles of IGFBPs family (IGFBP1-6) in breast cancer through the "Kaplan-Meier plotter" online database and OncoLnc database.Our results showed that the high expression of IGFBP1 mRNA was associated with favorable relapsed free survival (RFS) in all breast cancer patients. The high expression of IGFBP2 mRNA was associated with favorable overall survival (OS) and RFS in all breast cancer patients. The high expression of IGFBP3 mRNA was significantly correlated to worsen RFS in all breast cancer patients. The high expression of IGFBP4 mRNA was associated with favorable OS, RFS, distant metastasis-free survival, and post-progression survival in all breast cancer patients.Our results indicated that expression of IGFBPs mRNA may have prognostic values in breast cancer patients, and have a benefit for developing tools to predict the prognosis more accurately.

Acute leukemia in a patient with 15q overgrowth syndrome

Overgrowth syndromes are rare genetic conditions which present as global or segmental hyperplasia and are sometimes associated with increased risk of malignancy. Trisomy of the terminal portion of 15q which includes the IGFR1 gene, produces a rare overgrowth phenotype that has been termed 15q overgrowth syndrome (15q OGS). Upregulation of IGF1R has long been implicated in oncogenesis of multiple cancer types, including acute leukemias, and has been shown to render cells more susceptible to other transforming events. To date, too few cases of 15q OGS have been reported to identify any cancer predisposition. We present a case of a 34-year-old female with intellectual disability, macrocephaly, and subtle dysmorphic features who was diagnosed with mixed phenotype acute leukemia (lymphoid and myeloid). Prior to initiation of therapy she was referred to medical genetics for further evaluation and was identified as having a chromosomal translocation resulting in a partial trisomy of chromosome 15q, consistent with 15q OGS. A review of the literature for cases of malignancy in individuals with increased copy number of 15q revealed only one other reported patient. Given the small number of reported individuals, we cannot rule out an increased risk of cancer associated with this chromosomal overgrowth syndrome. Although concerns have been raised regarding treatment feasibility in the setting of chromosomal disorders, the reported patient underwent successful treatment with allogeneic hematopoietic stem-cell transplant.

Evaluation of Insulin-mediated Regulation of AKT Signaling in Childhood Acute Lymphoblastic Leukemia

OBJECTIVE

Hyperglycemia increases the risk of early recurrence and high mortality in some adult blood cancers. In response to increased glucose levels, insulin is secreted, and several studies have shown that insulin-induced AKT signaling can regulate tumor cell proliferation and apoptosis. The AKT pathway is aberrantly activated in adult acute lymphoblastic leukemia (ALL), but the mechanisms underlying this activation and its impact in pediatric patients with ALL are unclear.

MATERIALS AND METHODS

We evaluated the insulin-induced chemoresistance and AKT pathway activation by measuring cell proliferation, apoptosis, and other parameters in ALL cell lines (Jurkat and Reh cells), as well as in primary pediatric leukemic cell samples, after culture with insulin, the chemotherapeutic drugs daunorubicin (DNR), vincristine (VCR), and L-asparaginase (L-Asp), or anti-insulin-like growth factor-1 receptor (IGF-1R) monoclonal antibody.

RESULTS

DNR, VCR, and L-Asp-induced toxicity in Jurkat and Reh cells was reduced in the presence of insulin. DNR promoted cell proliferation, whereas DNR, VCR, and L-Asp all reduced apoptosis in both cell lines cotreated with insulin compared with that in cell lines treated with chemotherapeutics alone (P<0.05). Furthermore, addition of an anti-IGF-1R monoclonal antibody promoted apoptosis, downregulated IGF-1R expression, and decreased the phosphorylation of AKT, P70S6K, and mTOR intracellular signaling pathway proteins in both cell lines, as well as in primary cultures (P<0.05).

CONCLUSIONS

Our results suggest that insulin-induced chemoresistance and activation of the AKT signaling pathway in pediatric ALL cells.

Metformin and blood cancers

Type 2 diabetes mellitus and cancer are correlated with changes in insulin signaling, a pathway that is frequently upregulated in neoplastic tissue but impaired in tissues that are classically targeted by insulin in type 2 diabetes mellitus. Many antidiabetes treatments, particularly metformin, enhance insulin signaling, but this pathway can be inhibited by specific cancer treatments. The modulation of cancer growth by metformin and of insulin sensitivity by anticancer drugs is so common that this phenomenon is being studied in hundreds of clinical trials on cancer. Many meta-analyses have consistently shown a moderate but direct effect of body mass index on the incidence of multiple myeloma and lymphoma and the elevated risk of leukemia in adults. Moreover, new epidemiological and preclinical studies indicate metformin as a therapeutic agent in patients with leukemia, lymphomas, and multiple myeloma. In this article, we review current findings on the anticancer activities of metformin and the underlying mechanisms from preclinical and ongoing studies in hematologic malignancies.

WITHDRAWN: Emodin increases expression of insulin-like growth factor binding protein 1 through activation of MEK/ERK/AMPKα and interaction of PPARγ and Sp1 in lung cancer

Due to an error in the publishing process, this article has been withdrawn at the request of the editors. We wish to clarify that this is in no way related to the integrity of the authors. The Publisher apologizes for any inconvenience this may cause. The full Elsevier Policy on Article Withdrawal can be found at http://www.elsevier.com/locate/withdrawalpolicy.

IGF1R Derived PI3K/AKT Signaling Maintains Growth in a Subset of Human T-Cell Acute Lymphoblastic Leukemias

Insulin-like growth factor 1 receptor (IGF1R) is a prevalent signaling pathway in human cancer that supports cell growth/survival and thus contributes to aggressive biological behavior. Much work has gone into development of IGF1R inhibitors; however, candidate agents including small molecule tyrosine kinase inhibitors and blocking antibodies have yet to fulfill their promise clinically. Understanding cellular features that define sensitivity versus resistance are important for effective patient selection and anticipation of outgrowth of a resistant clone. We previously identified an important role for IGF signaling in T-cell acute lymphoblastic leukemia (T-ALL) relying primarily upon genetically defined mouse models. We present here an assessment of IGF1R dependence in human T-ALL using a broad panel of 27 established cell lines that capture a spectrum of the genetic variation that might be encountered in clinical practice. We observed that a subset of cell lines are sensitive to IGF1R inhibition and are characterized by high levels of surface IGF1R expression and PTEN positivity. Interestingly, lentiviral expression or knock-down of PTEN in PTEN-negative/positive cell lines, respectively, had limited effects on their response to IGF1R inhibition, suggesting that PTEN contributes to, but does not define IGF dependence. Additionally, we characterize downstream PI3K/AKT signaling as dominant over RAS/RAF/MEK/ERK in mediating growth and/or survival in this context. Finally, we demonstrate that IGF and interleukin-7 (IL-7) fulfill non-overlapping roles in supporting T-ALL growth. These findings are significant in that they reveal cellular features and downstream mechanisms that may determine the response of an individual patient’s tumor to IGF1R inhibitor therapy.

Chinese Herbal Medicine Fuzheng Kang-Ai Decoction Inhibited Lung Cancer Cell Growth through AMPKα-Mediated Induction and Interplay of IGFBP1 and FOXO3a

The aim of this study is to investigate the actions of Chinese herbal medicine, called “Fuzheng Kang-Ai” (FZKA for short) decoction, against non-small cell lung cancer (NSCLC) and its mechanisms in vitro and in vivo. We showed that the effect of FZKA decoction significantly inhibited growth of A549 and PC9 cells. Furthermore, FZKA increased phosphorylation of AMP-activated protein kinase alpha (AMPKα) and induced protein expression of insulin-like growth factor (IGF) binding protein 1 (IGFBP1) and forkhead homeobox type O3a (FOXO3a). The specific inhibitor of AMPKα (Compound C) blocked FZKA-induced protein expression of IGFBP1 and FOXO3a. Interestingly, silencing of IGFBP1 and FOXO3a overcame the inhibitory effect of FZKA on cell growth. Moreover, silencing of IGFBP1 attenuated the effect of FZKA decoction on FOXO3a expression, and exogenous expression of FOXO3a enhanced the FZKA-stimulated phosphorylation of AMPKα. Accordingly, FZKA inhibited the tumor growth in xenograft nude mice model. Collectively, our results show that FZKA decoction inhibits proliferation of NSCLC cells through activation of AMPKα, followed by induction of IGFBP1 and FOXO3a proteins. Exogenous expression of FOXO3a feedback enhances FZKA decoction-stimulated IGFBP1 expression and phosphorylation of AMPKα. The reciprocal interplay of IGFBP1 and FOXO3a contribute to the overall responses of FAKA decoction.

Ph-like ALL-related novel fusion kinase ATF7IP-PDGFRB exhibits high sensitivity to tyrosine kinase inhibitors in murine cells

ATF7IP-PDGFRB is a novel PDGFRB-related fusion gene identified in B-cell precursor acute lymphoblastic leukemia (BCP-ALL) with a signature similar to that of Ph1 ALL, so-called Ph-like ALL. When we introduced ATF7IP-PDGFRB, murine Ba/F3 cells acquired the ability to proliferate in an interleukin (IL)-3-independent manner. On the contrary, the expression of wild-type PDGFRB is not sufficient to acquire the ability for IL-3-independent proliferation in Ba/F3 cells. The introduction of ATF7IP-PDGFRB also induces a typical gene expression profile for Ph1-ALL in Ba/F3 cells. A series of biochemical and cell biological experiments revealed the constitutive activation of ATF7IP-PDGFRB as well as downstream signaling molecules, including AKT and MAPK. Although the phosphoinositide 3-kinase inhibitor led to cell death in both cells into which ATF7IP-PDGFRB had been introduced and IL-3-maintained Mock cells, MEK inhibitor selectively led to cell death into which ATF7IP-PDGFRB had been introduced. The introduction of tyrosine to phenylalanine mutations at binding sites of adaptor molecules important in the MAPK pathway located in the PDGFRB portion abolished ATF7IP-PDGFRB-mediated cell transformation, suggesting that MAPK-mediated signals are critical in ATF7IP-PDGFRB-mediated cell transformation. On treatment with tyrosine kinase inhibitors, ATF7IP-PDGFRB-expressing, but not Mock, Ba/F3 cells underwent rapid apoptosis accompanied by reduced phosphorylation of MAPK. Importantly, the sensitivity of ATF7IP-PDGFRB-expressing Ba/F3 cells to imatinib is significantly higher than that of BCR-ABL1-transformed Ba/F3 cells, as assessed by the IC50. Taken together, ATF7IP-PDGFRB has transforming potential via the constitutive activation of MAPK and participates in the pathogenesis of Ph-like ALL. Our observations suggest the therapeutic importance of tyrosine kinase inhibitors and possibly MEK inhibitor for a subset of BCP-ALL harboring PDGFRB-related fusion kinases.

Targeting bone marrow lymphoid niches in acute lymphoblastic leukemia

In acute lymphoblastic leukemia (ALL) the bone marrow microenvironment provides growth and survival signals that may confer resistance to chemotherapy. Granulocyte colony-stimulating factor (G-CSF) potently inhibits lymphopoiesis by targeting stromal cells that comprise the lymphoid niche in the bone marrow. To determine whether lymphoid niche disruption by G-CSF sensitizes ALL cells to chemotherapy, we conducted a pilot study of G-CSF in combination with chemotherapy in patients with relapsed or refractory ALL. Thirteen patients were treated on study; three patients achieved a complete remission (CR/CRi) for an overall response rate of 23%. In the healthy volunteers, G-CSF treatment disrupted the lymphoid niche, as evidenced by reduced expression of CXCL12, interleukin-7, and osteocalcin. However, in most patients with relapsed/refractory ALL expression of these genes was markedly suppressed at baseline. Thus, although G-CSF treatment was associated with ALL cell mobilization into the blood, and increased apoptosis of bone marrow resident ALL cells, alterations in the bone marrow microenvironment were modest and highly variable. These data suggest that disruption of lymphoid niches by G-CSF to sensitize ALL cells to chemotherapy may be best accomplished in the consolidation where the bone marrow microenvironment is more likely to be normal.

Dendritic cell-mediated survival signals in Eμ-Myc B-cell lymphoma depend on the transcription factor C/EBPβ

The capacity of dendritic cells (DCs) to regulate tumour-specific adaptive immune responses depends on their proper differentiation and homing status. Whereas DC-associated tumour-promoting functions are linked to T-cell tolerance and formation of an inflammatory milieu, DC-mediated direct effects on tumour growth have remained unexplored. Here we show that deletion of DCs substantially delays progression of Myc-driven lymphomas. Lymphoma-exposed DCs upregulate immunomodulatory cytokines, growth factors and the CCAAT/enhancer-binding protein β (C/EBPβ). Moreover, Eμ-Myc lymphomas induce the preferential translation of the LAP/LAP* isoforms of C/EBPβ. C/EBPβ(-/-) DCs are unresponsive to lymphoma-associated cytokine changes and in contrast to wild-type DCs, they are unable to mediate enhanced Eμ-Myc lymphoma cell survival. Antigen-specific T-cell proliferation in lymphoma-bearing mice is impaired; however, this immune suppression is reverted by the DC-restricted deletion of C/EBPβ. Thus, we show that C/EBPβ-controlled DC functions are critical steps for the creation of a lymphoma growth-promoting and -immunosuppressive niche.

Cell-based assays for IGF-I bioactivity measurement: overview, limitations and current trends

Insulin-like growth factor-I (IGF-I) is an important growth promoting protein that is involved in numerous cellular responses and multiple biological systems. Although the molecular structure, function and recombinant production of IGF-I in various hosts have been the subject of much researches over the recent past, methods to determine the bioactivity of this protein have not been fully explored. Several assays have traditionally been used to measure IGF-I bioactivity, but have not become a routine laboratory practice due to the high cost involved and technical problems. Thus, there is still a need for a rapid, technically simple and accurate assay to determine IGF-I bioactivity. This review highlights the various cell-based assays currently commercially available for measuring the bioactivity of IGF-I along with their limitations. This is aimed at presenting the modern-day IGF researcher with a holistic overview of the current trends and future prospects regarding IGF-I bioactivity determinations.