The role of the insulin-like growth factor system in human cancer

Losartan rewires the tumor-immune microenvironment and suppresses IGF-1 to overcome resistance to chemo-immunotherapy in ovarian cancer

BACKGROUND

Ovarian cancer (OvCa) is the most lethal of the gynecologic malignancies. Immune checkpoint inhibitors, which have revolutionized the treatment of multiple malignancies, have had limited efficacy in OvCa patients. This lack of effectiveness is partly due to the abnormal ovarian tumor microenvironment (TME), displaying a desmoplastic, highly fibrotic extracellular matrix. High extracellular matrix deposition leads to a buildup of compressive forces that cause tumor blood vessel collapse, reduced vessel perfusion, poor delivery of drugs, and compromised trafficking of cytotoxic T-cells to these tumors.

METHODS

Using two syngeneic OvCa models, we tested the effect of losartan, a widely prescribed anti-hypertensive drug, on reprogramming the TME and chemosensitizing the cancer cells.

RESULTS

Losartan treatment (i) reprograms the TME leading to increased vascular perfusion, and thus enhances drug delivery and immune effector cell intratumoral infiltration and function; and (ii) rewires the OvCa cells by suppressing the IGF-1 signaling, resulting in enhanced chemosensitivity. As a result of the combined tumor and stromal effects, losartan treatment enhances the efficacy of chemo-immunotherapy in OvCa models.

CONCLUSION

The safety and low cost ( < $1-2/day) of losartan warrant rapid translation of our findings to patients with OvCa.

IGFBP-3 functions as a molecular switch that mediates mitochondrial and metabolic homeostasis

Mitochondrial dysfunction or loss of homeostasis is a central hallmark of many human diseases. Mitochondrial homeostasis is mediated by multiple quality control mechanisms including mitophagy, a form of selective autophagy that recycles terminally ill or dysfunctional mitochondria in order to preserve mitochondrial integrity. Our prior studies have shown that members of the insulin-like growth factor (IGF) family localize to the mitochondria and may play important roles in mediating mitochondrial health in the corneal epithelium, an integral tissue that is required for the maintenance of optical transparency and vision. Importantly, the IGF-binding protein-3, IGFBP-3, is secreted by corneal epithelial cells in response to stress and functions to mediate intracellular receptor trafficking in this cell type. In this study, we demonstrate a novel role for IGFBP-3 in mitochondrial homeostasis through regulation of the short isoform (s)BNIP3L/NIX mitophagy receptor in corneal epithelial cells and extend this finding to non-ocular epithelial cells. We further show that IGFBP-3-mediated control of mitochondrial homeostasis is associated with alterations in lamellar cristae morphology and mitochondrial dynamics. Interestingly, both loss and gain of function of IGFBP-3 drive an increase in mitochondrial respiration. This increase in respiration is associated with nuclear accumulation of IGFBP-3. Taken together, these findings support a novel role for IGFBP-3 as a key mediator of mitochondrial health in mucosal epithelia through the regulation of mitophagy and mitochondrial morphology.

Immunotherapy and Radioimmunotherapy for Desmoplastic Small Round Cell Tumor

Desmoplastic small round cell tumor (DRSCT) is a highly aggressive primitive sarcoma that primarily affects adolescent and young adult males. The 5-year survival rate is 15-30% and few curative treatment options exist. Although there is no standard treatment for DSRCT, patients are most often treated with a combination of aggressive chemotherapy, radiation, and surgery. Targeted therapy inhibitors of PDGFA and IGF-1R, which are almost uniformly overexpressed in DSRCT, have largely failed in clinical trials. As in cancer in general, interest in immunotherapy to treat DSRCT has increased in recent years. To that end, several types of immunotherapy are now being tested clinically, including monoclonal antibodies, radionuclide-conjugated antibodies, chimeric antigen receptor T cells, checkpoint inhibitors, and bispecific antibodies (BsAbs). These types of therapies may be particularly useful in DSRCT, which is frequently characterized by widespread intraperitoneal implants, which are difficult to completely remove surgically and are the frequent cause of relapse. Successful treatment with immunotherapy or radioimmunotherapy following debulking surgery could eradiate these micrometasteses and prevent relapse. Although there has been limited success to date for immunotherapy in pediatric solid tumors, the significant improvements in survival seen in the treatment of other pediatric solid tumors, such as metastatic neuroblastoma and its CNS spread, suggest a potential of immunotherapy and specifically compartmental immunotherapy in DSRCT.

Colostrogenesis: Role and Mechanism of the Bovine Fc Receptor of the Neonate (FcRn)

Colostrogenesis is a separate and unique phase of mammary epithelial cell activity occurring in the weeks before parturition and rather abruptly ending after birth in the bovine. It has been the focus of research to define what controls this process and how it produces high concentrations of specific biologically active components important for the neonate. In this review we consider colostrum composition and focus upon components that appear in first milked colostrum in concentrations exceeding that in blood serum. The Fc Receptor of the Neonate (FcRn) is recognized as the major immunoglobulin G (IgG) and albumin binding protein that accounts for the proteins' long half-lives. We integrate the action of the pinocytotic (fluid phase) uptake of extracellular components and merge them with FcRn in sorting endosomes. We define and explore the means of binding, sorting, and the transcytotic delivery of IgG1 while recycling IgG2 and albumin. We consider the means of releasing the ligands from the receptor within the endosome and describe a new secretion mechanism of cargo release into colostrum without the appearance of FcRn itself in colostrum. We integrate the insulin-like growth factor family, some of which are highly concentrated bioactive components of colostrum, with the mechanisms related to FcRn endosome action. In addition to secretion, we highlight the recent findings of a role of the FcRn in phagocytosis and antigen presentation and relate its significant and abrupt change in cellular location after parturition to a role in the prevention and resistance to mastitis infections.

MicroRNA-381-A Key Transcriptional Regulator: Its Biological Function and Clinical Application Prospects in Cancer

MicroRNAs (miRNAs) are small non-coding RNA molecules that function by regulating messenger RNAs. Recent studies have shown that miRNAs play important roles in multiple processes of cancer development. MiR-381 is one of the most important miRNAs in cancer progression. MiR-381 is downregulated in some cancers and upregulated in other cancers, including glioma, epithelial sarcoma, and osteosarcoma. MiR-381 regulates epithelial-mesenchymal transition (EMT), chemotherapeutic resistance, radioresistance, and immune responses. Thus, miR-381 participates in tumor initiation, progression, and metastasis. Moreover, miR-381 functions in various oncogenic pathways, including the Wnt/β-catenin, AKT, and p53 pathways. Clinical studies have shown that miR-381 could be considered a biomarker or a novel prognostic factor. Here, we summarize the present studies on the role of miR-381 in cancer development, including its biogenesis and various affected signaling pathways, and its clinical application prospects. MiR-381 expression is associated with tumor stage and survival time, making miR-381 a novel prognostic factor.

Identification of nephronectin as a new target for IGF1 action

INTRODUCTION

The growth hormone (GH)-insulin-like growth factor-1 (IGF1) endocrine axis has a key role in normal growth and development. Laron syndrome (LS) is a type of dwarfism that results from mutation of the GH receptor, leading to congenital IGF1 deficiency. Epidemiological studies have shown that LS patients are protected from cancer. Genome-wide profiling led to the identification of a series of metabolic genes whose differential expression in LS might be linked to cancer protection. Nephronectin (NPNT) is an intracellular and secreted extracellular matrix protein with important roles in kidney development. NPNT was identified as the top-downregulated gene in LS-derived cells in comparison with ethnic-, age- and gender-matched controls (p-value = 0.0148; fold-change = -3.12 versus controls). NPNT has not been previously linked to the IGF1 signaling pathway. The present study was aimed at evaluating the hypothesis that NPNT is a new target for IGF1 action and that decreased expression of NPNT in LS is correlated with cancer protection.

METHODS

Basal and IGF1-stimulated NPNT expression were assessed in LS lymphoblastoid cells as well as in human breast and prostate cancer cells. NPNT silencing experiments were conducted using siRNA methodology.

RESULTS

We provide evidence that IGF1 stimulates NPNT expression in LS-derived lymphoblastoids and various cancer cell lines. In addition, we demonstrate that NPNT silencing results in diminished activation of the AKT and ERK1/2 pathways, with ensuing decreases in cellular proliferation.

CONCLUSIONS

Our data identified the NPNT gene as a target for IGF1 action. The clinical implications of the functional and physical interactions between NPNT and the IGF1 pathway merit further investigation.

Coexpression of p-IGF-1R and MMP-7 Modulates Panitumumab and Cetuximab Efficacy in RAS Wild-Type Metastatic Colorectal Cancer Patients

INTRODUCTION

The coexpression of pIGF-1R and MMP-7 (double-positive phenotype, DP) correlates with poor overall survival (OS) in KRAS wild-type (WT) (exon 2) metastatic colorectal cancer (mCRC) patients treated with irinotecan-cetuximab in second/third line.

METHODS

We analyzed two prospective biomarker design trials of newly diagnosed RAS-WT mCRC patients treated with panitumumab-FOLFOX6 (PULSE trial; NCT01288339) or cetuximab plus either FOLFOX6/FOLFIRI (POSIBA trial; NCT01276379). The main exposure was DP phenotype (DP/non-DP), as assessed by two independent pathologists. DP cases were defined by immunohistochemistry as >70% expression of moderate or strong intensity for both MMP-7 and pIGF-1R. Primary endpoint: progression-free survival (PFS); secondary endpoints: OS and response rate. PFS and OS were adjusted by baseline characteristics using multivariate Cox models.

RESULTS

We analyzed 67 patients (30 non-DP, 37 DP) in the PULSE trial and 181 patients in the POSIBA trial (158 non-DP, 23 DP). Response rates and PFS were similar between groups in both studies. DP was associated with prolonged OS in PULSE (adjusted HR: 0.23; 95%CI: 0.11-0.52; P=.0004) and with shorter OS in POSIBA (adjusted HR: 1.67; 95%CI: 0.96-2.90; P=.07).

CONCLUSION

A differential effect of anti-EGFRs on survival by DP phenotype was observed. Panitumumab might be more beneficial for RAS-WT mCRC patients with DP phenotype, whereas cetuximab might improve OS in non-DP.

miR-342-3p suppresses hepatocellular carcinoma proliferation through inhibition of IGF-1R-mediated Warburg effect

Background

Insulin-like growth factor-1 receptor (IGF-1R) is a well-studied oncogenic factor that promotes cell proliferation and energy metabolism and is overexpressed in numerous cancers including hepatocellular carcinoma (HCC). Aerobic glycolysis is a hallmark of cancer, and drugs targeting its regulators, including IGF-1R, are being developed. However, the mechanisms of IGF-1R inhibition and the physiological significance of the IGF-1R inhibitors in cancer cells are unclear.

Materials and methods

Cell proliferation was evaluated by cell counting Kit-8 and colony formation assay. Western blot and real-time PCR were accordingly used to detect the relevant proteins, miRNA and gene expression. Luciferase reporter assays were used to illustrate the interaction between miR-342-3p and IGF-1R. The effect of miR-342-3p on glycolysis was determined by glucose uptake, ATP concentration, lactate generation, extracellular acidification rate and oxygen consumption rate assays. In vivo, subcutaneous tumor formation assay and PET were performed in nude mice.

Results

In this study, we demonstrate that by directly targeting the 3′-UTR (3′-untranslated regions) of IGF-1R, microRNA-342-3p (miR-342-3p) suppresses IGF-1R-mediated PI3K/AKT/GLUT1 signaling pathway both in vitro and in vivo. Through suppression of IGF-1R, miR-342-3p dampens glycolysis by decreasing glucose uptake, lactate generation, ATP production, and extracellular acidification rate (ECAR), and increasing oxygen consumption rate (OCR) in hepatoma cells. Importantly, glycolysis regulated by miR-342-3p is critical for its regulating HCC growth both in vitro and in vivo.

Conclusion

Our findings provide clues regarding the role of miR-342-3p as a tumor suppressor in liver cancer mainly through the inhibition of IGF-1R. Targeting IGF-1R by miR-342-3p could be a potential therapeutic strategy in liver cancer.

MicroRNA-302a inhibits osteosarcoma cell migration and invasion by directly targeting IGF-1R

Osteosarcoma is one of the most frequent types of primary malignant bone neoplasm in children and adolescents. Despite advancements developed in therapeutic modalities, the 5-year overall survival rates for patients with metastatic osteosarcoma disease remain poor. The present study aimed to investigate the expression level of microRNA-302a (miR-302a) in osteosarcoma tissues and cell lines, and the biological roles of miR-302a in osteosarcoma cells. In addition, the molecular mechanism underlying its tumor suppressive roles was evaluated. miR-302a expression in osteosarcoma tissues and cell lines was detected using reverse transcription-quantitative polymerase chain reaction (RT-qPCR). Following transfection of miR-302a mimics or IGF-1R siRNA, transwell migration and invasion, luciferase reporter assay RT-qPCR and western blot assays were conducted in osteosarcoma cells. In the present study, the data demonstrated that miR-302a was frequently reduced in osteosarcoma tissue and cell lines. In addition, the expression of miR-302a was correlated with metastatic features of patients with osteosarcoma. Restoration of miR-302a expression significantly inhibited the migration and invasion capacity of osteosarcoma cells. Mechanistic studies indicated that insulin-like growth factor 1 receptor (IGF-1R) was a direct target gene of miR-302a. Overexpression of miR-302a resulted in decreased expression of IGF-1R at the mRNA and protein levels. Furthermore, the knockdown IGF-1R mimicked the functions of miR-302a overexpression on osteosarcoma cell migration and invasion. Collectively, the results of the current study indicate that miR-302a acts as a metastasis suppressing miRNA and could be investigated as a therapeutic target for the treatment of patients with osteosarcoma to prevent metastasis.

Nuclear translocation of IGF1R by intracellular amphiregulin contributes to the resistance of lung tumour cells to EGFR-TKI

Many Receptor Tyrosine Kinases translocate from the cell surface to the nucleus in normal and pathological conditions, including cancer. Here we report the nuclear expression of insulin-like growth factor-1 receptor (IGF1R) in primary human lung tumours. Using lung cancer cell lines and lung tumour xenografts, we demonstrate that the epidermal growth factor receptor-tyrosine kinase inhibitor (EGFR-TKI) gefitinib induces the nuclear accumulation of IGF1R in mucinous lung adenocarcinoma by a mechanism involving the intracellular re-localization of the growth factor amphiregulin. Amphiregulin allows the binding of IGF1R to importin-β1 and promotes its nuclear transport. The nuclear accumulation of IGF1R by amphiregulin induces cell cycle arrest through p21^WAF1/CIP1 upregulation, and prevents the induction of apoptosis in response to gefitinib. These results identify amphiregulin as the first nuclear localization signal-containing protein that interacts with IGF1R and allows its nuclear translocation. Furthermore they indicate that nuclear expression of IGF1R contributes to EGFR-TKI resistance in lung cancer.

Effects of Parental Aging During Embryo Development and Adult Life: The Case of Nothobranchius furzeri

Studies on parental aging are a very attractive field, although it is poorly understood how parental age affects embryonic development and adult traits of the offspring. In this study, we used the turquoise killifish Nothobranchius furzeri, as is the vertebrate with shortest captive lifespan and an interesting model. The embryos of N. furzeri can follow two distinct developmental pathways either entering diapause or proceeding through direct development. Thus, this embryonic plasticity allows this model to be used to study different factors that could affect their embryonic development, including parental age. The first goal of the present study was to investigate whether parental aging could affect the embryo development. To do this, we collected F1 embryos from two breeder groups (old parents and young parents). We monitored the duration of embryonic development and analyzed genes involved in dorsalization process. The second goal was to investigate if embryonic developmental plasticity could be modulated by an epigenetic process. To this end, the expression of DNMTs genes was examined. Our data support the hypothesis that diapause, occurring more frequently in embryos from old parents, is associated with increased expression of DNMT3A and DNMT3B suggesting an epigenetic control. Finally, we analyzed whether parental age could affect metabolism and growth during adult life. Morphometric results and qPCR analysis of genes from IGF system showed a slower growth in adults from old breeders. Moreover, a gender-specificity effect on growth emerged. In conclusion, these results may contribute to the better understanding of the complex mechanism of aging.

MicroRNA-381 inhibits cell proliferation and invasion in endometrial carcinoma by targeting the IGF-1R

Endometrial carcinoma (EC) is the sixth most common type of malignant tumor occurring in females. MicroRNAs (miRNAs) serve as oncogenes or tumor suppressors in human cancer and play important roles in tumorigenesis, and tumor development by regulating various processes. Thus, further investigation into miRNAs involved in EC formation and progression may aid in developing effective therapeutic strategies for patients with this disease. miRNA‑381 (miR‑381) is aberrantly expressed in multiple types of human cancer. However, the expression pattern, biological roles and underlying mechanisms of miR‑381 in EC are poorly understood. In the present study, the results showed that miR‑381 was downregulated in EC tissues and cell lines. Decreased miR‑381 expression correlated with the International Federation of Gynecology and Obstetrics stage, lymph nodes metastasis and myometrial invasion of EC. The ectopic expression of miR‑381 significantly inhibited the proliferation and invasion of EC cells. Through a series of experiments, the insulin‑like growth factor receptor 1 (IGF‑1R) was identified as a novel direct target of miR‑381 in EC. Furthermore, IGF‑1R was highly expressed in EC tissues and inversely correlated with miR‑381 levels. IGF‑1R overexpression partially abrogated the tumor‑suppressive effects of miR‑381 on the proliferation and invasion of EC cells. miR‑381 targeted IGF‑1R to inactivate the protein kinase B (AKT) and extracellular signal‑regulated kinase (ERK) signaling pathways in EC. These results suggest that miR‑381 acts as a tumor suppressor in EC by directly targeting IGF‑1R, and indirectly regulating the AKT and ERK signaling pathways. Thus, miR‑381 should be investigated as a prognostic biomarker and novel therapeutic target for the treatment of patients with EC.

Nuclear IGF-1R predicts chemotherapy and targeted therapy resistance in metastatic colorectal cancer

Background:

Although chemotherapy is the cornerstone treatment for patients with metastatic colorectal cancer (mCRC), acquired chemoresistance is common and constitutes the main reason for treatment failure. Monoclonal antibodies against insulin-like growth factor-1 receptor (IGF-1R) have been tested in pre-treated mCRC patients, but results have been largely deceiving.

Methods:

We analysed time to progression, overall survival, and the mutational status of RAS, BRAF and nuclear p-IGF-1R expression by immunohistochemistry, in 470 metastatic CRC patients. The effect of IGF-1R activation and distribution was also assessed using cellular models of CRC and RNAi for functional validation.

Results:

Nuclear IGF-1R increased in metastatic tumours compared to paired untreated primary tumours, and significantly correlated with poor overall survival in mCRC patients. In vitro, chemo-resistant cell lines presented significantly higher levels of IGF-1R expression within the nuclear compartment, and PIAS3, a protein implicated also in the sumoylation process of intranuclear proteins, contributed to IGF-1R nuclear sequestration, highlighting the essential role of PIAS3 in this process. Intriguingly, we observed that ganitumab, an IGF-1R blocking-antibody used in several clinical trials, and dasatinib, an SRC inhibitor, increased the nuclear localisation of IGF-1R.

Conclusions:

Our study demonstrates that IGF-1R nuclear location might lead to chemotherapy and targeted agent resistance.

Overexpression of Glypican 3 Promotes Proliferation, Regulates Cell Cycle Progression, and Inhibits Apoptosis of Human Fetal Osteoblastic Cell Line 1.19

Craniosynostosis is a complex disease condition, which involves premature fusion of cranial vault sutures and lacks desirable treatment. Previous studies have demonstrated decreased proliferation rate of osteoblasts and downregulated expression of glypican 3 (GPC3) in syndromic craniosynostosis patients. In this study, quantitative and qualitative analysis were utilized to assess the effect of GPC3 in human fetal osteoblastic cell line, hFOB 1.19. Lentiviral transfection efficiency with green fluorescent protein images was obtained after 72 hours. Western Blot and quantitative real-time polymerase chain reaction analysis results indicated that GPC3 was overexpressed in hFOB 1.19 cells transfected with recombinant lentivirus LV-GPC3-GFP. Cell proliferation was assessed by CCK-8 assay and cell cycle progression and apoptosis were analyzed by flow cytometric assay. Results revealed that GPC3 promoted cell viability, induced cell cycle entry into S phase, and inhibited cell apoptosis. These findings provide novel ideas in understanding the pathogenesis of craniosynostosis. It also provides novel insights in the treatment of craniosynostosis by targeting GPC3.

MicroRNA-379 acts as a tumor suppressor in non-small cell lung cancer by targeting the IGF‑1R-mediated AKT and ERK pathways

Lung cancer is one of the most common types of malignancy in humans and is a leading cause of cancer-related deaths among men and women worldwide. Aberrantly expressed microRNAs in non-small cell lung cancer (NSCLC) contribute to tumor occurrence and development as either tumor suppressors or promoters. MicroRNA-379 (miR‑379) is dysregulated in several types of human cancer. However, its expression pattern, role and underlying mechanism in NSCLC progression and metastasis are poorly understood. In this study, assay of reverse transcription-quantitative polymerase chain reaction showed that miR‑379 was downregulated in both NSCLC tissue and cell lines. Low miR‑379 expression in NSCLC tissues was significantly correlated with TNM stage and lymph node metastasis. In addition, functional experiments revealed that restoring the expression of miR‑379 inhibited cell proliferation, migration and invasion of NSCLC. The insulin-like growth factor receptor-1 (IGF‑1R) was identified as a direct target of miR‑379 in NSCLC. IGF‑1R was highly expressed in NSCLC tissues and inversely correlated with miR‑379 expression. Downregulation of IGF‑1R had tumor suppressive roles similar to that of miR‑379 overexpression on NSCLC cell proliferation, migration and invasion. Moreover, the upregulation of IGF‑1R effectively rescued the tumor suppressive roles induced by miR‑379 overexpression in NSCLC. The resumption of the expression of miR‑379 inhibited the activation of AKT and ERK signaling pathways in NSCLC. These findings suggested that miR‑379 acts as a tumor suppressor in NSCLC by directly targeting IGF‑1R and indirectly regulating AKT and ERK signaling pathways. miR‑379 provides novel therapeutic targets for the treatment of patients with this disease.

MicroRNA-184 inhibits cell proliferation and metastasis in human colorectal cancer by directly targeting IGF-1R

Colorectal cancer is currently the third most common cancer in males and the second in females worldwide. In spite of marked progress having been achieved in surgical resection, radiotherapy and chemotherapy, the prognosis for patients with colorectal cancer remains poor. Previous studies have demonstrated that the abnormal expression of microRNAs contributed to human cancer carcinogenesis and progression, suggesting miRNAs as novel therapeutic targets in colorectal cancer. The aim of the present study was to investigate the expression, functions and underlying molecular mechanisms of microRNA-184 (miR-184) in colorectal cancer. The results identified that miR-184 was significantly downregulated in colorectal cancer tissues and cell lines. In vitro functional studies demonstrated that miR-184 significantly inhibited colorectal cancer cell proliferation, migration and invasion. Notably, insulin-like growth factor 1 receptor (IGF-1R) was identified as a direct target of miR-184 in colorectal cancer. Furthermore, the functions of IGF-1R small interfering RNA were similar to those induced by miR-184 in colorectal cancer, suggesting IGF-1R as a functional target of miR-184 in colorectal cancer. The results of the present study indicated that miR-184 may be a novel therapeutic strategy regimen of targeted therapy for colorectal cancer.

MicroRNA-592 targets IGF-1R to suppress cellular proliferation, migration and invasion in hepatocellular carcinoma

MicroRNAs (miRs) can function as tumor suppressors or oncogenes in different types of human malignancy, and may provide an effective therapy for cancer. The expression and functions of miR-592 have previously been studied in relation to cancer. However, the expression and potential functions of miR-592 in hepatocellular carcinoma (HCC) are still unknown. Using quantitative polymerase chain reaction, MTT assays, cellular migration and invasion assays, bioinformatics software, western blot analysis and dual-luciferase report assays, the present study explored the expression and roles of miR-592 in HCC. It was identified that miR-592 was significantly downregulated in HCC tissues and cell lines. The statistical analysis revealed that low expression of miR-592 was evidently associated with tumor node metastasis stage and lymph node metastasis. Additionally, the present study provided the first evidence that miR-592 was likely to directly target the insulin-like growth factor 1 receptor in vitro. The present results indicated that miR-592 could be investigated as an efficacious therapeutic target for HCC in the future.

MicroRNA-320a is downregulated in non-small cell lung cancer and suppresses tumor cell growth and invasion by directly targeting insulin-like growth factor 1 receptor

Accumulating evidence has demonstrated that microRNAs (miRs/miRNAs) are implicated in carcinogenesis and cancer progression, and can function as oncogenes or tumor suppressor genes in human cancer types. Previous profile studies of miRNA expression levels have revealed that miR-320a was downregulated in breast cancer, colon cancer, bladder cancer, glioblastoma and salivary adenoid cystic carcinoma. However, its expression level, potential functions and the mechanisms underlying its functions in non-small cell lung cancer (NSCLC) require further investigation. The present study investigated the expression level, biological roles and underlying molecular mechanisms of miR-320a in NSCLC. The expression levels of miR-320a in NSCLC tissue and cell lines were detected using the reverse transcription-quantitative polymerase chain reaction. Cell proliferation and Transwell invasion assays were performed to examine the effects of miR-320a on NSCLC cells. In addition, bioinformatic analysis, western blot analysis and luciferase reporter assays were performed to identify the direct gene target of miR-320a in NSCLC. In the present study it was demonstrated that miR-320a was significantly downregulated in NSCLC tissues and cell lines. Ectopic overexpression of miR-320a suppressed the proliferation and invasion of NSCLC cells. Further studies indicated that miR-320a directly targeted the 3'-untranslated region of insulin-like growth factor 1 receptor (IGF-1R) and suppressed its expression at the mRNA and protein levels. As well as restoring the miR-320a expression level, the knockdown of IGF-1R also decreased the growth and invasion of the NSCLC cells. These results suggested that miR-320a served as a tumor suppressor in the NSCLC cells by directly targeting IGF-1R. Therefore, miR-320a should be investigated as a therapeutic target for the treatment of NSCLC.

Hemodialysis for Lactic Acidosis

Lactic acidosis (Type A) is common in critically ill patients and usually treated by correcting the underlying etiology. We present the case of a young female who presented with life-threatening lactic acidosis secondary to hematological malignancy. Timely initiation of hemodialysis was lifesaving. The case highlights the importance of considering Type B lactic acidosis (in this case secondary to a hematological malignancy) and also initiating renal replacement therapy when routine measures are ineffective.

The Emerging Role of the Insulin-like Growth Factors in Oral Biology

The insulin-like growth factors (IGF) are a family of growth factors, receptors and binding proteins that are involved in numerous growth and differentiation processes, as well as in various pathological conditions. The aim of this review is to summarize data that has been accumulating in recent years linking the IGF system to a number of physiological and pathological oral processes. The IGF system fulfills an important role in growth and development of teeth, mandible, maxillae, and tongue. It has been postulated that IGF-I may be of great value in the treatment of periodontal defects and in tissue healing. Furthermore, IGF-II has been shown to be overexpressed in salivary gland adenomas, suggesting that aberrant IGF signaling may be a key factor in the etiology of oral malignancies. Understanding the role and regulation of IGF system components in salivary glands and other oral structures will be of significant basic and clinical relevance.

Effects of the Insulin-like Growth Factor Pathway on the Regulation of Mammary Gland Development

The insulin-like growth factor (IGF) pathway is a key signal transduction pathway involved in cell proliferation, migration, and apoptosis. In dairy cows, IGF family proteins and binding receptors, including their intracellular binding partners, regulate mammary gland development. IGFs and IGF receptor interactions in mammary glands influence the early stages of mammogenesis, i.e., mammary ductal genesis until puberty. The IGF pathway includes three major components, IGFs (such as IGF-I, IGF-II, and insulin), their specific receptors, and their high-affinity binding partners (IGF binding proteins [IGFBPs]; i.e., IGFBP1–6), including specific proteases for each IGFBP. Additionally, IGFs and IGFBP interactions are critical for the bioactivities of various intracellular mechanisms, including cell proliferation, migration, and apoptosis. Notably, the interactions between IGFs and IGFBPs in the IGF pathway have been difficult to characterize during specific stages of bovine mammary gland development. In this review, we aim to describe the role of the interaction between IGFs and IGFBPs in overall mammary gland development in dairy cows.

Insulin-like Growth Factor 1 Signaling Axis Meets p53 Genome Protection Pathways

Clinical, epidemiological, and experimental evidence indicate that the insulin-like growth factors (IGFs) are important mediators in the biochemical chain of events that lead from a phenotypically normal to a neoplastic cell. The IGF1 receptor (IGF1R), which mediates the biological actions of IGF1 and IGF2, exhibits potent pro-survival and antiapoptotic activities. The IGF1R is highly expressed in most types of cancer and is regarded as a promising therapeutic target in oncology. p53 is a transcription factor with tumor suppressor activity that is usually activated in response to DNA damage and other forms of cellular stress. On the basis of its protective activities, p53 is commonly regarded as the guardian of the genome. We provide evidence that the IGF signaling axis and p53 genome protection pathways are tightly interconnected. Wild-type, but not mutant, p53 suppresses IGF1R gene transcription, leading to abrogation of the IGF signaling network, with ensuing cell cycle arrest. Gain-of-function, or loss-of-function, mutations of p53 in tumor cells may disrupt its inhibitory activity, thus generating oncogenic molecules capable of transactivating the IGF1R gene. The interplay between the IGF1 and p53 pathways is also of major relevance in terms of metabolic regulation, including glucose transport and glycolysis. A better understanding of the complex physical and functional interactions between these important signaling pathways will have major basic and translational relevance.

Expression and function of microRNA-497 in human osteosarcoma

The expression and function of microRNA-497 (miR-497) has previously been reported in various types of human cancer; however, miR-497 has not previously been investigated in human osteosarcoma (OS). In the present study, the expression levels of miR‑497 were analyzed by reverse transcription‑quantitative polymerase chain reaction (RT‑qPCR) in OS tissues and cell lines. In addition, post-transfection with miR‑497, RT‑qPCR, cell proliferation, migration and invasion assays, western blot analysis, and luciferase assays were performed in OS cell lines. The results of the present study demonstrated that miR‑497 was downregulated in OS tissues and cells compared with normal controls. Furthermore, upregulation of miR‑497 inhibited cell proliferation, migration and invasion in osteosarcoma cell lines compared with the negative control group. In addition, the present study demonstrated that miR‑497 may function by directly targeting insulin‑like growth factor 1 receptor in OS cells. These findings indicated that miR‑497 may be useful as a therapeutic target for the treatment of OS.

Type I insulin-like growth factor as a liver reserve assessment tool in hepatocellular carcinoma

Chronic liver diseases (CLDs) encompass a wide range of illnesses, including nonalcoholic fatty liver disease, nonalcoholic steatohepatitis, and viral hepatitis. Deterioration of liver capacity, with subsequent progression into cirrhosis and hepatocellular carcinoma (HCC), ultimately leads to a further decrease in the hepatic reserve. The Child-Turcotte-Pugh scoring system is the standard tool for assessing underlying liver reserve capacity in routine practice and in clinical trials of CLD and HCC. In this review, we highlight the clinical significance of insulin-like growth factor-I (IGF-I) and the growth hormone (GH) signaling pathway in HCC. IGF-I could be a marker for liver reserve capacity in CLDs and HCC in clinical practice. This approach could improve the risk assessment and stratifications of patients on the basis of their underlying liver reserve, either before active treatment in routine practice or before they are enrolled in clinical trials.

Molecular cloning of the insulin-like growth factor 3 and difference in the expression of igf genes in orange-spotted grouper (Epinephelus coioides)

Insulin-like growth factor (Igf) is the key regulator for development, growth, and reproduction. In most vertebrate species, the Igf family has two forms: Igf1 and Igf2. A novel form of Igf, termed Igf3, was recently discovered in fish. In the present study, we isolated igf3 from the orange-spotted grouper (Epinephelus coioides). The orange-spotted grouper igf3 consisted of a full-length cDNA of 1014 nucleotides with an open reading frame (ORF) of 597 bp, encoding for proteins of 199 amino acid residues in length. Tissue distribution analysis showed that igf1 widely expressed with the highest expression in the pituitary and liver. igf2 was expressed highly in all the tissues except the olfactory bulb, while igf3 showed the highest expression in the ovary, and moderate expression in brain areas. The expression profiles of three igf genes during the ovarian development and growth hormone (Gh) and human chorionic gonadotropin (hCG) treatment were also investigated. Three igf genes exhibited different expression patterns during the ovarian development, and showed different responses to the Gh and hCG treatments, appearing to play distinct roles in ovarian development. The present study provides further evidence for the existence of an intraovarian Igf system in orange-spotted grouper.

Hyaluronan/RHAMM interactions in mesenchymal tumor pathogenesis: role of growth factors

Fibrosarcoma belongs to the sarcoma cancer group, which are spindle cell malignancies of mesenchymal origin, and owe their name to the predominant cell line that is present within the tumor. The extracellular matrix (ECM) is a complicated structure that surrounds and supports cells within tissues. Its main components are proteoglycans, collagens, glycoproteins, hyaluronan (HA), and several matrix-degrading enzymes. During cancer progression, significant changes can be observed in the structural and mechanical properties of ECM components. The ECM provides a physical scaffold to which tumor cells attach and migrate. Thus, it is required for key cellular events such as cell motility, adhesion, proliferation, invasion, and metastasis. Importantly, fibrosarcomas were shown to have a high content and turnover of ECM components including HA, proteoglycans, collagens, fibronectin, and laminin. In this review, we will focus on the HA component of fibrosarcoma ECM and critically discuss its role and involved mechanisms during fibrosarcoma pathogenesis.

Cloning, molecular characterization and expression analysis of insulin-like growth factor binding protein-2 (IGFBP-2) cDNA in goldfish, Carassius auratus

In the present study, a full-length cDNA encoding the insulin-like growth factor binding protein-2 (IGFBP-2) was cloned from the liver of goldfish (Carassius auratus) by rapid amplification of cDNA ends technique. The goldfish IGFBP-2 cDNA sequence was 1,513 bp long and had an open reading frame of 825 bp encoding a predicted polypeptide of 274 amino acid residues. Semi-quantitative RT-PCR results revealed that goldfish IGFBP-2 mRNA was expressed in all detected tissues. In liver, central nervous system and pituitary gland, goldfish IGFBP-2 expressed at high levels, followed by anterior intestine, middle intestine and kidney. In posterior intestine, ovary, skin, fat, spleen, muscle and gill, the goldfish IGFBP-2 expression levels were very low. Fasting and refeeding experiment showed that the mRNA expression of goldfish IGFBP-2 was up-regulated significantly in liver compared to the fed group and restored rapidly to normal level after refed. However, the mRNA expressions of IGFBP-2 in hypothalamus and pituitary of goldfish were insensitive to fasting. Furthermore, the mRNA expressions of IGFBP-2 in hypothalamus, pituitary and liver were varied in periprandial changes and significantly down-regulated at 2 and 4 h after meal. These results imply that the IGFBP-2 mRNA expression may be associated with anabolic and catabolic metabolism and regulated by metabolic factors in goldfish.

SUMOylation of insulin-like growth factor 1 receptor, promotes proliferation in acute myeloid leukemia

Current valid treatments for acute myeloid leukemia (AML) include chemotherapy and hematopoietic stem cell transplantation, which are defective and limited respectively. The insulin-like growth factor 1 receptor (IGF-1R) is up-regulated in many solid tumors; therefore, it may be a target for tumor therapy. Interestingly, IGF-1R is modified by SUMOylation, a type of reversible post-translational modification. In this study, we found that IGF-1R was increased in both cell lines and clinical samples of AML and was modified by SUMO-1. Furthermore, IGF-1, ligand of IGF-1R, induced the up-regulation of IGF-1R and increased the proliferation of leukemia cell line. After mutation of Lys(1025) and Lys(1100) in IGF-1R, the evolutionarily conserved lysine residues were identified as the SUMOylation sites of IGF-1R, because the SUMOylation of IGF-1R in these mutants was significantly inhibited. Furthermore, the cell proliferation mediated by IGF-1 was also reduced. After inhibition of UBC9, the activating enzyme of SUMOylation, co-expression of IGF-1R and SUMO-1 was down-regulated, and cell proliferation was also inhibited. However, cell apoptosis was not significantly affected. These results suggest that IGF-1R and its SUMOylation may be a new therapeutic target for strategy of AML.

Association between dairy intake and gastric cancer: a meta-analysis of observational studies

Purpose

Observational studies have given inconsistent findings on the relationship between intake of dairy products and gastric cancer. We therefore conducted a systematic review with a meta-analysis of observational studies to summarize available evidence on this point.

Methods

We searched the electronic literature databases of PubMed (Medline), EMBASE and the Chinese Biomedical Literature Database up until August 30, 2013. All studies were limited to the English language. Random-effects models were used to pool study results between dairy products consumption and the risk of gastric cancer. We also performed subgroup, publication bias and sensitivity analysis.

Results

Eight prospective studies and 18 case-control studies were included in our analysis, with a total number of 7272 gastric cancer cases and 223,355 controls. Pooled relative risks of all studies showed no significant association between dairy intake and gastric cancer (odds ratio [OR]: 1.09, 95% confidence interval [CI]: 0.96–1.25). When study design was separately analyzed, population-based case-control studies showed a positive association between dairy intake and gastric cancer risk (OR: 1.36; 95% CI: 1.07–1.74), whereas no associations were shown by hospital-based case-control studies (OR: 0.86, 95% CI: 0.72–1.02) or cohort studies (OR = 1.01, 95% CI = 0.91–1.13).

Conclusions

The meta-analysis shows that no clear association apparently exists between consumption of dairy products and gastric cancer risk. Further well-designed cohort and intervention studies should be conducted to verify this lack of association.

Molecular cloning, expression profiles and promoter analysis of insulin-like growth factor binding protein-4 (IGFBP-4) in Japanese flounder (Paralichthys olivaceus)

We cloned and characterized cDNA sequence of insulin-like growth factor binding protein-4 (IGFBP-4) from Japanese flounder (Paralichthys olivaceus). The 1493 bp full-length cDNA sequence contained an open reading frame (ORF) of 780 bp, which encoded a protein of 259 amino acids. The deduced amino acid sequences included a putative signal peptide of 28 amino acid residues resulting in a mature protein of 231 amino acids. Twenty cysteine residues and two conserved IGFBPs motif (GCGCCXXC and CWCV) were found in the N- and C-terminal domain. In the over 13 kbp genomic sequence, four exons, three introns, and 5'-/3'-flanking sequences were identified. Sequence alignment and phylogenetic analysis showed that Japanese flounder IGFBP-4 was indeed the ortholog of the human IGFBP-4 gene and shared high identities with other teleost IGFBP-4 genes. The promoter region was also analyzed and several potential transcription factor (TF) binding sites were determined which may modulate the IGFBP-4 expression. Quantitative real-time PCR analysis revealed that IGFBP-4 mRNA was observed in various tissues, with intestine showing the highest expression. The maternal transcripts of IGFBP-4 gene existed in the early embryonic stages and then increased in the following stages until hatching, suggesting that IGFBP-4 may be involved in the fish early development. The expression level of IGFBP-4 mRNA was relatively higher at 3 days post hatching (dph) and 15 dph, and gradually decreased during the metamorphosis period. All these results indicated that IGFBP-4 plays a significant role in IGF regulating vertebrate growth and development.

IGF1 induces cell proliferation in human pituitary tumors - functional blockade of IGF1 receptor as a novel therapeutic approach in non-functioning tumors

Insulin-like growth factor (IGF1) and its receptor display potent proliferative and antiapoptotic activities and are considered key players in malignancy. The objective of the study was to explore the role of IGF1 and its downstream pathways in the proliferation of non-functioning pituitary tumor cells and to develop a targeted therapeutic approach for the treatment of these tumors. Cultures of human non-functioning pituitary adenomas and the non-secreting immortalized rat pituitary tumor cell line MtT/E were incubated with IGF1, IGF1 receptor inhibitor or both, and cell viability, proliferation and signaling were examined. Our results show that IGF1 elevated cell proliferation and enhanced cell cycle progression as well as the expression of cyclins D1 and D3. IGF1 also induced the phosphorylation of ERK, Akt and p70S6K. On the other hand, the selective IGF1R inhibitor NVP-AEW541 abrogated IGF1-induced cell proliferation as well as IGF1 receptor phosphorylation and downstream signaling.

Antibodies directed against receptor tyrosine kinases: current and future strategies to fight cancer

Approximately 30 therapeutic monoclonal antibodies have already been approved for cancers and inflammatory diseases, and monoclonal antibodies continue to be one of the fastest growing classes of therapeutic molecules. Because aberrant signaling by receptor tyrosine kinases (RTKs) is a commonly observed factor in cancer, most of the subclasses of RTKs are being extensively studied as potential targets for treating malignancies. The first two RTKs that have been targeted by antibody therapy, with five currently marketed antibodies, are the growth factor receptors EGFR and HER2. However, due to systemic side effects, refractory patients and the development of drug resistance, these treatments are being challenged by emerging therapeutics. This review examines current monoclonal antibody therapies against RTKs. After an analysis of agents that have already been approved, we present an analysis of antibodies in clinical development that target RTKs. Finally, we highlight promising RTKs that are emerging as new oncological targets for antibody-based therapy.

The complexity of the IGF1 gene splicing, posttranslational modification and bioactivity

The insulinlike growth factor-I (IGF-I) is an important factor which regulates a variety of cellular responses in multiple biological systems. The IGF1 gene comprises a highly conserved sequence and contains six exons, which give rise to heterogeneous mRNA transcripts by a combination of multiple transcription initiation sites and alternative splicing. These multiple transcripts code for different precursor IGF-I polypeptides, namely the IGF-IEa, IGF-IEb and IGF-IEc isoforms in humans, which also undergo posttranslational modifications, such as proteolytic processing and glycosylation. IGF-I actions are mediated through its binding to several cell-membrane receptors and the IGF-I domain responsible for the receptor binding is the bioactive mature IGF-I peptide, which is derived after the posttranslational cleavage of the pro-IGF-I isoforms and the removal of their carboxy-terminal E-peptides (that is, the Ea, Eb and Ec). Interestingly, differential biological activities have been reported for the different IGF-I isoforms, or for their E-peptides, implying that IGF-I peptides other than the IGF-I ligand also possess bioactivity and, thus, both common and unique or complementary pathways exist for the IGF-I isoforms to promote biological effects. The multiple peptides derived from IGF-I and the differential expression of its various transcripts in different conditions and pathologies appear to be compatible with the distinct cellular responses observed to the different IGF-I peptides and with the concept of a complex and possibly isoform-specific IGF-I bioactivity. This concept is discussed in the present review, in the context of the broad range of modifications that this growth factor undergoes which might regulate its mechanism(s) of action.

Circulating concentrations of C-Peptide and colorectal adenoma

Hyperinsulinemia may increase the risk of colorectal neoplasia because of its mitogenic and antiapoptotic properties, which have a growth-promoting effect. We examined the association between circulating concentrations of C-peptide, a biomarker of insulin secretion, and colorectal adenoma prevalence in a case-control study of Korean adults. A total of 364 participants (112 cases and 252 controls) were included. Participants who underwent a colonoscopy completed questionnaires and provided blood samples. We used multivariate logistic regression models to obtain odds ratios (ORs) and 95% confidence intervals (CIs) for colorectal adenoma. Circulating concentrations of C-peptide were not associated with colorectal adenoma; the multivariate OR (95% CI) was 0.95 (0.51-1.75) comparing the highest tertile with the lowest tertile (p for trend = 0.91). When we used a conditional logistic regression model by fasting status and sex matching, there was still no association (OR = 0.92; 95% CI = 0.43-1.99) when comparing the highest tertile with the lowest tertile. We observed no association between circulating concentrations of C-peptide and colorectal adenoma prevalence in Korean adults.

Nutrient pathways and breast cancer risk: the Long Island Breast Cancer Study Project

The relative importance of biochemical pathways has not been previously examined when considering the influence of diet on breast cancer risk. To address this issue, we used interview data from a population-based sample of 1463 breast cancer cases and 1500 controls. Dietary intake was assessed shortly after diagnosis using a 101-item food frequency questionnaire. Age- and energy-adjusted odds ratios (ORs) for individual micro- and macronutrients were estimated with logistic regression. Hierarchical modeling was used to account for biologically plausible nutrient pathways (1-carbon metabolism, oxidative stress, glycemic control, and phytoestrogens). Effect estimates from hierarchical modeling were more precise and plausible compared to those from multivariable models. The strongest relationship observed was for the glycemic control pathway, but confidence intervals (CI) were wide [OR (95% CI): 0.86 (0.62, 1.21)]. Little or no effect was observed for the 1-carbon metabolism, oxidative stress, and phytoestrogen pathways. Associations were similar when stratified by supplement use. Our approach that emphasizes biochemical pathways, rather than individual nutrients, revealed that breast cancer risk may be more strongly associated with glycemic control factors than those from other pathways considered. Our study emphasizes the importance of accounting for multiple nutrient pathways when examining associations between dietary intake and breast cancer.

Targeting non-small cell lung cancer cells by dual inhibition of the insulin receptor and the insulin-like growth factor-1 receptor

Phase III trials of the anti-insulin-like growth factor-1 receptor (IGF1R) antibody figitumumab in non-small cell lung cancer (NSCLC) patients have been discontinued owing to lack of survival benefit. We investigated whether inhibition of the highly homologous insulin receptor (IR) in addition to the IGF1R would be more effective than inhibition of the IGF1R alone at preventing the proliferation of NSCLC cells. Signalling through IGF1R and IR in the NSCLC cell lines A549 and Hcc193 was stimulated by a combination of IGF1, IGF2 and insulin. It was inhibited by antibodies that block ligand binding, αIR3 (IGF1R) and IR47-9 (IR), and by the ATP-competitive small molecule tyrosine kinase inhibitors AZ12253801 and NVPAWD742 which inhibit both IGF1R and IR tyrosine kinases. The effect of inhibitors was determined by an anchorage-independent proliferation assay and by analysis of Akt phosphorylation. In Hcc193 cells the reduction in cell proliferation and Akt phosphorylation due to anti-IGF1R antibody was enhanced by antibody-mediated inhibition of the IR whereas in A549 cells, with a relatively low IR:IGF1R expression ratio, it was not. In each cell line proliferation and Akt phosphorylation were more effectively inhibited by AZ12253801 and NVPAWD742 than by combined αIR3 and IR47-9. When the IGF1R alone is inhibited, unencumbered signalling through the IR can contribute to continued NSCLC cell proliferation. We conclude that small molecule inhibitors targeting both the IR and IGF1R more effectively reduce NSCLC cell proliferation in a manner independent of the IR:IGF1R expression ratio, providing a therapeutic rationale for the treatment of this disease.

The type 1 insulin-like growth factor receptor signalling system and targeted tyrosine kinase inhibition in cancer

Type 1 insulin-like growth factor receptor (IGF1R) signalling plays a critical role in normal cell growth, and in cancer development and progression. IGF1R and the insulin-like growth factors 1 and 2 (IGF1 and IGF2) are involved in various aspects of the malignant phenotype, suggesting that IGF1R is a potential target for cancer therapy. IGF1R is particularly important in the establishment and maintenance of the transformed phenotype, in mediating proliferation, and for the survival of tumour cells with anchorage-independent growth. IGF1R also exerts antiapoptotic activity and has a substantial influence on the control of the cell and body size. This property enables transformed cells to form macroscopic tumours and to survive the process of detachment required for metastasis. Pharmaceutical companies are investigating molecules that target IGF1R, including specific low molecular weight tyrosine kinase inhibitors and monoclonal antibodies, both of which possess various advantages and display different activity profiles. This review article focuses on the preclinical and clinical development of low molecular weight IGF1R tyrosine kinase inhibitors. It is critical to pursue a thorough molecular analysis of the metabolic activity of IGF1R to avoid possible side-effects of its inhibition.

Targeting IGF-1 signaling pathways in gynecologic malignancies

INTRODUCTION

The signaling pathways of the insulin-like growth factors (IGF) have been implicated in the etiology of a number of epithelial neoplasms including prostate, breast, colon and more recently, gynecologic cancers. The insulin-like growth factor-1 receptor (IGF-1R) is expressed in most transformed cells, where it displays potent anti-apoptotic, cell-survival and potentially, transforming activities. IGF-1R expression and activation are typical hallmarks associated with tumor initiation and progression. Multiple approaches have been used to abrogate IGF-1R signaling for targeted cancer therapy including antibodies and small molecule tyrosine kinase inhibitors. These novel IGF-1R targeting agents have produced significant experimental and clinical results in many cancers and generated considerable optimism in the field of cancer therapy.

AREAS COVERED

The authors will review important research advances regarding the role of the IGF axis in cancer, particularly preclinical and clinical studies in cervical, uterine and ovarian cancers. The significance of tumor expression and circulating levels of the IGF pathway as well as targeting therapies of the IGF axis in the gynecologic cancers will be discussed.

EXPERT OPINION

Accumulating data confirm that the IGF-1R pathway has an important role in gynecologic cancers and in vivo and in vitro studies have shown a significant impact of IGF-1R targeted therapies in these malignancies, mainly ovarian and endometrial cancers. Currently, ongoing preclinical and clinical trials are evaluating the efficacy of IGF-1R targeting. A better understanding of the complex mechanisms underlying the regulation of the IGF system will improve the ability to develop effective treatment modalities for these malignancies.

Evidence for the Possible Biological Significance of the igf-1 Gene Alternative Splicing in Prostate Cancer

Insulin-like growth factor-I (IGF-I) has been implicated in the pathogenesis of prostate cancer (PCa), since it plays a key role in cell proliferation, differentiation, and apoptosis. The IGF-I actions are mediated mainly via its binding to the type I IGF receptor (IGF-IR), however IGF-I signaling via insulin receptor (IR) and hybrid IGF-I/IR is also evident. Different IGF-I mRNA splice variants, namely IGF-IEa, IGF-IEb, and IGF-IEc, are expressed in human cells and tissues. These transcripts encode several IGF-I precursor proteins which contain the same bioactive product (mature IGF-I), however, they differ by the length of their signal peptides on the amino-terminal end and the structure of the extension peptides (E-peptides) on the carboxy-terminal end. There is an increasing interest in the possible different role of the IGF-I transcripts and their respective non-(mature)IGF-I products in the regulation of distinct biological activities. Moreover, there is strong evidence of a differential expression profile of the IGF-I splice variants in normal versus PCa tissues and PCa cells, implying that the expression pattern of the various IGF-I transcripts and their respective protein products may possess different functions in cancer biology. Herein, the evidence that the IGF-IEc transcript regulates PCa growth via Ec peptide specific and IGF-IR/IR-independent signaling is discussed.

Phase 1 study of ganitumab (AMG 479), a fully human monoclonal antibody against the insulin-like growth factor receptor type I (IGF1R), in Japanese patients with advanced solid tumors

PURPOSE

This study was to investigate the safety and tolerability of ganitumab in Japanese patients with advanced solid tumors.

METHODS

Patients were enrolled into 1 of 3 dose cohorts (6, 12, or 20 mg/kg) of single-agent ganitumab administered intravenously every 2 weeks. Dose-limiting toxicity (DLT) was assessed for the first 28 days. The primary objectives were to assess the safety, tolerability, and pharmacokinetics (PK) of ganitumab in Japanese patients with advanced solid tumors. An exploratory pharmacodynamic analysis was done to investigate the relationship between exposure and changes in the level of circulating factors in IGF1R pathway (IGFBP-3 and total IGF-1).

RESULTS

Nineteen patients with ECOG performance status 0-1 (6 in cohort 1 and 3, 7 in cohort 2) received at least 1 dose of ganitumab. Median age was 58.0 years. Tumor types included: breast (4), gastric (3), rectal (2), NSCLC (2), thymic (2), and other cancers (6). No DLTs were observed. The most common grade ≥3 adverse events were neutropenia (21 %), leukopenia (16 %) and lymphopenia (11 %). There was a trend of dose-dependency on severity of thrombocytopenia, but not on that of neutropenia. No neutralizing anti-ganitumab antibodies were detected during this study. Dose-linearity on PK of ganitumab was indicated in the dose range. Tumor response was assessed for 19 patients. Stable disease as best response was reported in 7 patients.

CONCLUSIONS

Ganitumab up to 20 mg/kg was tolerable in Japanese patients with advanced solid tumors. The safety and PK profiles were similar to those previously observed in non-Japanese patients.

A longitudinal study of the metabolic syndrome and risk of colorectal cancer in postmenopausal women

The metabolic syndrome is associated with increased risk of diabetes and coronary heart disease. Although higher BMI and other related factors have been frequently associated with colorectal cancer, whether the metabolic syndrome is associated with the risk of colorectal cancer is unclear. We therefore assessed the association of the metabolic syndrome with the risk of colorectal cancer in a subsample of participants of the Women's Health Initiative who had repeated measurements of the components of the syndrome at baseline and during follow-up. Women with diabetes at baseline enrollment were excluded. Cox proportional hazards models were used to estimate hazard ratios (HRs) and 95% confidence intervals (95% CI) at baseline and in time-dependent analyses. Among 4862 eligible women, 81 incident cases of colorectal cancer were identified over a median follow-up of 12 years. Presence of the metabolic syndrome at baseline was associated with increased risk of colorectal cancer (HR 2.15, 95% CI 1.30-3.53) and colon cancer (HR 2.28, 95% CI 1.31-3.98). These associations were largely explained by positive associations of serum glucose and systolic blood pressure with both outcomes. Time-dependent covariate analyses supported the baseline findings. Our results suggest that the positive association of the metabolic syndrome with risk of colorectal cancer is largely accounted for by serum glucose levels and systolic blood pressure. The biological mechanism underlying these associations remains to be clarified.

Targeting the mTOR-DEPTOR pathway by CRL E3 ubiquitin ligases: therapeutic application

The mammalian target of rapamycin (mTOR), an evolutionarily conserved serine/threonine protein kinase, integrates both intracellular and extracellular signals and serves as a central regulator of cell metabolism, growth, proliferation, survival, and autophagy. The mTOR pathway is frequently activated in many human cancers, mainly resulting from alterations in the upstream regulators, such as phosphoinositide 3-kinase (PI3K)/AKT activation, PTEN loss or dysregulation of mTOR-negative regulators (e.g., TSC1/2), leading to uncontrolled proliferation. Thus, inhibiting the PI3K/AKT/mTOR pathways is widely considered as an effective approach for targeted cancer therapy. Recently, we and others found that DEPTOR, a naturally occurring inhibitor of both mTORC1 and mTORC2, was degraded by SCF (Skp1-Cullin-F box proteins) E3 ubiquitin ligase, the founding member of cullin-RING-ligases (CRLs), resulting in mTOR activation and cell proliferation. In addition to DEPTOR, previous studies have demonstrated that several other negative regulators of mTOR pathway are also substrates of CRL/SCF E3s. Thus, targeting CRL/SCF E3s is expected to cause the accumulation of these mTOR signal inhibitors to effectively block the mTOR pathway. In this review, we will discuss mTOR signaling pathway, how DEPTOR regulates mTOR/AKT axis, thus acting as a tumor suppressor or oncogene in some cases, how DEPTOR is ubiquitinated and degraded by SCF(β-TrCP) E3, and how MLN4924, a small-molecule indirect inhibitor of CRL/SCF E3 ligases through blocking cullin neddylation, might be useful as a novel approach of mTOR pathway targeting for cancer therapy.

Cellular distribution of the IGF-1R in corneal epithelial cells

This study characterized the expression and subcellular localization of the IGF-1R in human corneal epithelial cells. Using a human telomerase-immortalized corneal epithelial cell line, IGF-1R expression and localization was assayed by immunofluorescence and subcellular fractionation followed by western blot. IGF-1R expression was confirmed in primary cultured human corneal epithelial cells. Nuclear localization was assessed under basal and IGF-1 stimulated culture conditions; phosphorylation status of the receptor in response to IGF-1 was demonstrated by western blot. IGF-1R:E-cadherin interactions were detected by immunofluorescence and co-immunoprecipitation of whole cell lysates. The results of this study demonstrated that IGF-1R localized predominantly to the nucleus and in a perinuclear cap pattern which co-localized with the Golgi complex in proliferating corneal epithelial cells. There was no difference in nuclear localization between primary or telomerized cell lines. Subcellular fractionation confirmed IGF-1Rα- and β-subunit localization in soluble and chromatin-bound nuclear fractions. Neither growth factor withdrawal nor IGF-1 stimulation altered nuclear IGF-1R. At points of cell-cell contact, IGF-1R co-localized with E-cadherin; co- immunoprecipitation assays confirmed the presence of an IGF-1R:E-cadherin complex. Importantly, this is the first report to identify IGF-1R in the nucleus and complexed with E-cadherin at points of cell-cell contact in corneal epithelial cells. Nuclear trafficking appeared to be independent of ligand-mediated events at the plasma membrane. The identification of IGF-1R in the nucleus and complexed with E-cadherin suggests novel regulatory functions outside the canonical ligand-induced endocytosis signaling pathway.

A longitudinal study of serum insulin and glucose levels in relation to colorectal cancer risk among postmenopausal women

Background:

It is unclear whether circulating insulin or glucose levels are associated with increased risk of colorectal cancer. Few prospective studies have examined this question, and only one study had repeated measurements.

Methods:

We conducted a prospective study of colorectal cancer risk using the subsample of women in the Women's Health Initiative study whose fasting blood samples, collected at baseline and during follow-up, were analysed for insulin and glucose. Cox proportional hazards models were used to assess associations with colorectal cancer risk in both baseline and time-dependent covariates analyses.

Results:

Among 4902 non-diabetic women with baseline fasting serum insulin and glucose values, 81 incident cases of colorectal cancer were identified over 12 years of follow-up. Baseline glucose levels were positively associated with colorectal cancer and colon cancer risk: multivariable-adjusted hazard ratio (HR) comparing the highest (⩾99.5 mg dl⁻¹) with the lowest tertile (<89.5 mg dl⁻¹): 1.74, 95% confidence interval (CI) 0.97–3.15 and 2.25, 95% CI: 1.12–4.51, respectively. Serum insulin and homeostasis model assessment were not associated with risk. Analyses of repeated measurements supported the baseline results.

Conclusion:

These data suggest that elevated serum glucose levels may be a risk factor for colorectal cancer in postmenopausal women.

Plasma and tissue insulin-like growth factor-I receptor (IGF-IR) as a prognostic marker for prostate cancer and anti-IGF-IR agents as novel therapeutic strategy for refractory cases: a review

Cancer database analysis indicates that prostate cancer is one of the most seen cancers in men meanwhile composing the leading cause of morbidity and mortality among developed countries. Current available therapies are surgery, radiotherapy and androgene ablation for prostate carcinoma. The response rate is as high nearly 90% however, most of these recur or become refractory and androgene independent (AI). Therefore recent studies intensified on molecular factors playing role on development of prostate carcinoma and novel treatment strategies targetting these factors and their receptors. Insulin-like growth factor-I (IGF-I) and its primary receptor insulin-like growth factor receptor-I (IGF-IR) are among these factors. Biologic functions and role in malign progression are primarily achieved via IGF-IR which is a type 2 tyrosine kinase receptor. IGF-IR plays an important role in mitogenesis, angiogenesis, transformation, apoptosis and cell motility. It also generates intensive proliferative signals leading to carcinogenesis in prostate tissue. So IGF-IR and its associated signalling system have provoked considerable interest over recent years as a novel therapeutic target in cancer. In this paper it is aimed to sum up the lately published literature searching the relation of IGF-IR and prostate cancer in terms of incidence, pathologic features, and prognosis. This is followed by a discussion of the different possible targets within the IGF-1R system, and drugs developed to interact at each target. A systems-based approach is then used to review the in vitro and in vivo data in the published literature of the following compounds targeting IGF-1R components using specific examples: growth hormone releasing hormone antagonists (e.g. JV-1-38), growth hormone receptor antagonists (e.g. pegvisomant), IGF-1R antibodies (e.g. CP-751,871, AVE1642/EM164, IMC-A12, SCH-717454, BIIB022, AMG 479, MK-0646/h7C10), and IGF-1R tyrosine kinase inhibitors (e.g. BMS-536942, BMS-554417, NVP-AEW541, NVP-ADW742, AG1024, potent quinolinyl-derived imidazo (1,5-a)pyrazine PQIP, picropodophyllin PPP, nordihydroguaiaretic acid Insm-18/NDGA). And the other end point is to yield an overview on the recent progress about usage of this receptor as a novel anticancer agent of targeted therapies in treatment of prostate carcinoma.