Inhibition of the type I insulin-like growth factor receptor expression and signaling: novel strategies for antimetastatic therapy

Association of Diabetes Severity and Mortality with Lung Squamous Cell Carcinoma

Simple Summary

The survival impact of diabetes severity on lung cancer survival remains unclear. We performed head-to-head propensity score matching to estimate the survival impact of various adapted diabetes complications severity index (aDCSI) scores in patients with both diabetes and lung squamous cell carcinoma (SqCLC). The results indicated that diabetes severity (aDCSI ≥ 2) is an independent prognostic factor for the overall survival of patients with both diabetes and lung SqCLC who receive standard treatments. Prevention of diabetes progression is necessary for patients with diabetes; it affects not only diabetes control but also improves survival for patients with lung SqCLC.

Abstract

Purpose: The survival impact of diabetes severity on lung cancer remains unclear. We performed head-to-head propensity score matching to estimate the survival impact of various adapted diabetes complications severity index (aDCSI) scores in patients with both diabetes and lung squamous cell carcinoma (SqCLC). Patients and Methods: We enrolled patients with both diabetes and lung SqCLC and categorized them into the mild (aDCSI = 0–1) and moderate-to-severe (aDCSI ≥ 2) diabetes groups. The patients in both groups were matched at a 1:1 ratio. Results: the matching process yielded a final cohort of 5742 patients with both diabetes and lung SqCLC (2871 patients in the mild diabetes group and 2871 patients in the moderate-to-severe diabetes groups) who were eligible for further analysis. A multivariate Cox regression analysis revealed that the adjusted hazard ratio (aHR; 95% confidence interval) of all-cause death for the mild diabetes group relative to the moderate-to-severe diabetes group was 1.17 (1.08–1.28; p = 0.0005). Conclusion: severe diabetes (aDCSI ≥ 2) is an independent prognostic factor for OS among patients with both diabetes and lung SqCLC who receive standard treatments. Preventing diabetes progression is necessary for patients with diabetes because it not only supports diabetes control but also improves survival for patients with lung SqCLC.

Prognostic significance of preoperative haemoglobin A1c level in patients with lung adenocarcinoma

OBJECTIVES

We investigated the influence of the preoperative haemoglobin A1c (HbA1c) value on the prognosis and pathology of patients with lung adenocarcinoma who underwent surgery.

METHODS

We reviewed the medical records of 400 lung adenocarcinoma patients who underwent lobectomy with mediastinal lymph node dissection between 2009 and 2013 using a prospectively maintained database. We stratified 400 patients into 4 groups according to the preoperative HbA1c value as follows: HbA1c ≤ 5.9 (n = 296), 6.0 ≤ HbA1c ≤ 6.9 (n = 70), 7.0 ≤ HbA1c ≤ 7.9 (n = 21) and HbA1c ≥ 8.0 (n = 12). We compared the recurrence-free survival and overall survival (OS) among these 4 groups. Univariate and multivariate analyses were performed to identify the risk factors for recurrence.

RESULTS

The median follow-up period was 61.2 months. On comparing the recurrence-free survival and OS rates among these 4 groups, we found that these rates among patients in the HbA1c ≥ 8.0 group were significantly poorer compared with the other 3 groups (5-year recurrence-free survival: HbA1c ≤ 5.9, 70.4%; 6.0 ≤ HbA1c ≤ 6.9, 69.7%; 7.0 ≤ HbA1c ≤ 7.9, 70.7%; ≥8.0 HbA1c, 18.8%; P = 0.002; and 5-year OS: HbA1c ≤ 5.9, 88.7%; 6.0 ≤ HbA1c ≤ 6.9, 80.6%; 7.0 ≤ HbA1c ≤ 7.9, 90.2%; ≥8.0 HbA1c, 66.7%; P = 0.046). Patients in the HbA1c ≥ 8.0 group had significantly more tumours with vascular invasion (P = 0.041) and experienced distant metastasis significantly more often (P = 0.028) than those with other values. A multivariate analysis revealed that preoperative HbA1c ≥ 8.0 [hazard ratio (HR) 2.33; P = 0.026] and lymph node metastasis (HR 3.94; P < 0.001) were significant independent prognostic factors for recurrence.

CONCLUSIONS

Our results revealed that preoperative HbA1c ≥ 8.0 is associated to poor prognosis due to the occurrence of distant metastasis and we should carefully follow these patients after surgery.

CLINICAL REGISTRATION NUMBER

Hyogo Cancer Center, G-57.

Identification of a Resistance Mechanism to IGF-IR Targeting in Human Triple Negative MDA-MB-231 Breast Cancer Cells

Triple negative breast cancer (TNBC) is associated with unfavorable prognosis and high relapse rates following chemotherapy. There is an urgent need to develop effective targeted therapy for this BC subtype. The type I insulin-like growth factor receptor (IGF-IR) was identified as a potential target for BC management. We previously reported on the production of the IGF-Trap, a soluble IGF-1R fusion protein that reduces the bioavailability of circulating IGF-1 and IGF-2 to the cognate receptor, impeding signaling. In nude mice xenotransplanted with the human TNBC MDA-MB-231 cells, we found variable responses to this inhibitor. We used this model to investigate potential resistance mechanisms to IGF-targeted therapy. We show here that prolonged exposure of MDA-MB-231 cells to the IGF-Trap in vitro selected a resistant subpopulation that proliferated unhindered in the presence of the IGF-Trap. We identified in these cells increased fibroblast growth factor receptor 1 (FGFR1) activation levels that sensitized them to the FGFR1-specific tyrosine kinase inhibitor PD166866. Treatment with this inhibitor caused cell cycle arrest in both the parental and resistant cells, markedly increasing cell death in the latter. When combined with the IGF-Trap, an increase in cell cycle arrest was observed in the resistant cells. Moreover, FGFR1 silencing increased the sensitivity of these cells to IGF-Trap treatment in vivo. Our data identify increased FGFR1 signaling as a resistance mechanism to targeted inhibition of the IGF-IR and suggest that dual IGF-1R/FGFR1 blockade may be required to overcome TNBC cell resistance to IGF-axis inhibitors.

PYP1-4 peptide from Pyropia yezoensis protects against acetaminophen-induced hepatotoxicity in HepG2 cells

Acetaminophen (APAP) is a widely used analgesic and antipyretic. It is safe at normal treatment doses; however, APAP overdose is a major cause of acute liver and kidney failure. A variety of methods to reduce the damage caused by APAP overdose have previously been evaluated. The protein-rich seaweed Pyropia yezoensis has antioxidant, antitumor and anti-inflammatory activities, and protects against cytotoxicity. However, little is known regarding the protective effects of P. yezoensis peptide against APAP-induced hepatotoxicity. The present study investigated the ability of P. yezoensis peptide (PYP1-4) to ameliorate the damage caused by APAP-induced hepatotoxicity using HepG2 as the model cell line in addition to the signaling pathways involved. Briefly, cell viability, nitric oxide, reactive oxygen species and apoptosis assays were performed in conjunction with western blot analysis and reverse transcription-quantitative PCR. First, the present study revealed the minimum toxic concentration of APAP (15 mM) and the resting concentration of PYP1-4 (0–500 ng/ml). Administration of PYP1-4 to APAP-induced cells decreased the nitric oxide and reactive oxygen species levels, and restored the levels of antioxidant-associated proteins (catalase, heme oxygenase 1, superoxide dismutase 2 and quinone oxidoreductase 1). PYP1-4 increased the translocation of nuclear factor, erythroid 2 like 2 to the nucleus and the activities of glycogen synthase kinase-3β, Akt and AMP-activated protein kinase. In addition, APAP induced apoptosis; however, PYP1-4 inhibited apoptosis by modulating the levels of pro-apoptotic markers (Bad), anti-apoptotic markers (Bcl-2 and BH3 interacting domain death agonist), caspases and poly (ADP-ribose) polymerase 1. Subsequently, the insulin-like growth factor 1 receptor signaling pathway was investigated to determine whether PYP1-4 treatment restored the levels of cell growth-associated factors during APAP-induced hepatotoxicity. PYP1-4 treatment impacted the levels of components of the insulin receptor substrate 1/PI3K/Akt and Ras/Raf/ERK signaling pathways, and promoted cell survival. Therefore, the P. yezoensis peptide PYP1-4 may be useful for preventing APAP-induced hepatotoxicity.

The Effect of Diabetes Mellitus on Lung Cancer Prognosis: A PRISMA-compliant Meta-analysis of Cohort Studies

Previous studies suggested that diabetes mellitus (DM) was associated with risk and mortality of cancer, but studies investigating the correlation between DM and lung cancer prognosis remain controversial. Herein, a meta-analysis was performed to derive a more precise estimate of the prognostic role of DM in lung cancer.Medline and Embase were searched for eligible articles from inception to October 25, 2015. The pooled hazard ratio (HR) with its 95% confidence interval (95% CI) was calculated to evaluate the correlation between DM and lung cancer prognosis. Subgroup meta-analysis was performed based on the histology and the treatment methods.A total of 20 cohort studies from 12 articles were included in the meta-analysis. Also, 16 studies investigated the overall survival (OS) and 4 studies investigated the progression-free survival (PFS). DM was significantly associated with the inferior OS of lung cancer with the pooled HR 1.28 (95% CI: 1.10-1.49, P = 0.001). The association was prominent in the nonsmall cell lung cancer (NSCLC) subgroup (HR 1.35, 95%CI: 1.14-1.60, P = 0.002), whereas the association was not significant in the small cell lung cancer (SCLC) subgroup (HR 1.33, 95% CI: 0.87-2.03, P = 0.18). When NSCLC patients were further stratified by treatment methods, DM had more influence on the surgically treated subgroup than the nonsurgically treated subgroup. There was no obvious evidence for publication bias by Begg's and Egger's test.The results of this meta-analysis exhibit an association of DM with inferior prognosis amongst lung cancer patients, especially the surgically treated NSCLC patients. Given the small number of studies included in this meta-analysis, the present conclusion should be consolidated with more high-quality prospective cohort studies or randomized controlled trials.

Clinical significance of IGF1R gene expression in patients with Stage II/III gastric cancer who receive curative surgery and adjuvant chemotherapy with S-1

PURPOSE

Curative resection and adjuvant chemotherapy is the standard treatment for Stage II/III gastric cancer, and S-1 is widely used for adjuvant chemotherapy. The type 1 insulin-like growth factor receptor (IGF1R) is involved in cell proliferation and prevention of apoptosis in many tumors. We evaluated the relative expression of the IGF1R gene to determine whether such expression correlates with outcomes in patients with Stage II/III gastric cancer.

METHODS

We measured the expression levels of the IGF1R gene in specimens of cancer and adjacent normal mucosa obtained from 134 patients with Stage II/III gastric cancer who received curative resection and adjuvant chemotherapy with S-1. We then evaluated whether the IGF1R gene expression levels correlate with clinicopathological characteristics and outcomes.

RESULTS

IGF1R mRNA expression levels tended to be higher in cancer tissue than in the normal adjacent mucosa (P = 0.078). Multivariate analysis showed that high IGF1R gene expression was a significant independent predictor of poor survival in Stage II/III gastric cancer after curative resection and adjuvant chemotherapy with S-1 (HR 3.681, P = 0.007). The overall survival rate was significantly lower in patients with high IGF1R gene expression than in those with low expression (P = 0.012).

CONCLUSIONS

IGF1R overexpression is considered a useful independent predictor of outcomes in Stage II/III gastric cancer after curative resection and adjuvant chemotherapy with S-1.

The Impact of Diabetes Mellitus on Renal Cell Carcinoma Prognosis: A Meta-Analysis of Cohort Studies

Previous studies that investigated the relationship between DM and survival in renal cell carcinoma (RCC) patients reported inconsistent findings. Hence, we conducted a meta-analysis to obtain a more precise evaluation of the prognostic significance of DM in RCC. A systematic review was conducted with PubMed, Embase, and Web of Science to identify relevant articles that evaluated the effect of DM on RCC patients. Based on the inclusion and quality assessment criteria, 18 studies were eligible for the meta-analysis. Pooled hazard ratios (HR) and corresponding 95% confidence intervals (CI) for overall survival (OS), cancer-specific survival (CSS), and recurrence-free survival (RFS) were calculated by standard meta-analysis techniques. The results suggested that DM was associated with poor OS (HR 1.56, 95% CI, 1.35-1.81, P < 0.001), poor CSS (HR 2.03, 95% CI, 1.37-3.01, P < 0.001), and poor RFS (HR 1.73, 95% CI, 1.25-2.39, P = 0.012). In addition, for patients with localized RCC, patients with clear cell RCC, or patients receiving nephrectomy, DM was associated with both poor OS and CSS by subgroup analyses. Our study revealed that there was a significant negative impact of DM on OS, CSS, and RFS in RCC patients. Therefore, more attention should be paid to RCC patients with preexisting DM because of their poor prognosis.

BMS-536924, an ATP-competitive IGF-1R/IR inhibitor, decreases viability and migration of temozolomide-resistant glioma cells in vitro and suppresses tumor growth in vivo

Glioma is the most common type of primary brain tumor. Despite the combination of surgery, chemotherapy, and radiotherapy, the median survival duration of patients with malignant glioma is still very short. Temozolomide (TMZ) is the primary and most promising therapeutic drug for glioma; however, it is easy to develop acquired resistance during treatment. Activation of receptor tyrosine kinases (RTKs) has been identified to be involved in the acquisition of resistance toward many anticancer drugs. So inhibition of RTKs might be a promising therapeutic strategy for overcoming or attenuating acquired drug resistance. Here, we have investigated the anticancer activities of BMS-536924, an ATP-competitive IGF-1R/IR inhibitor in glioma, especially TMZ-resistant glioma, both in vitro and in vivo. We found that BMS-536924 could effectively reduce viability of both TMZ-sensitive and -resistant glioma cells. BMS-536924 induced dramatic apoptosis in TMZ-resistant cells, and it also dramatically inhibited migration of TMZ-resistant cells. Importantly, BMS-536924 significantly suppressed glioma tumor growth in vivo. This is the first report on anticancer activity of BMS-536924 in glioma. BMS-536924 is a promising compound in the therapy of glioma, especially of TMZ-resistant glioma, which might shed new light on glioma therapy.

Insulin-like growth factor 1 induces the transcription of Gap43 and Ntn1 during hair cell protection in the neonatal murine cochlea

We previously reported that insulin-like growth factor 1 (IGF-1) protects cochlear hair cells against aminoglycosides through activation of the PI3K/Akt and MEK/ERK pathways in supporting cells. In this study, we found that IGF-1 up-regulated the expression levels of Gap43 and Ntn1 as measured using cDNA microarray analysis and qRT-PCR. Using inhibitors of the PI3K/Akt and MEK/ERK pathways, we reveal that both pathways are involved in the up-regulation of Gap43 and Ntn1 expression. Moreover the time window of Gap43 and Ntn1 transcription was limited to within 12h after IGF-1 treatment, indicating that downstream gene expression was tightly controlled by IGF-1.

Something old, something new and something borrowed: emerging paradigm of insulin-like growth factor type 1 receptor (IGF-1R) signaling regulation

The insulin-like growth factor type 1 receptor (IGF-1R) plays a key role in the development and progression of cancer; however, therapeutics targeting it have had disappointing results in the clinic. As a receptor tyrosine kinase (RTK), IGF-1R is traditionally described as an ON/OFF system, with ligand stabilizing the ON state and exclusive kinase-dependent signaling activation. Newly added to the traditional model, ubiquitin-mediated receptor downregulation and degradation was originally described as a response to ligand/receptor interaction and thus inseparable from kinase signaling activation. Yet, the classical model has proven over-simplified and insufficient to explain experimental evidence accumulated over the last decade, including kinase-independent signaling, unbalanced signaling, or dissociation between signaling and receptor downregulation. Based on the recent findings that IGF-1R “borrows” components of G-protein coupled receptor (GPCR) signaling, including β-arrestins and G-protein-related kinases, we discuss the emerging paradigm for the IGF-1R as a functional RTK/GPCR hybrid, which integrates the kinase signaling with the IGF-1R canonical GPCR characteristics. The contradictions to the classical IGF-1R signaling concept as well as the design of anti-IGF-1R therapeutics treatment are considered in the light of this paradigm shift and we advocate recognition of IGF-1R as a valid target for cancer treatment.

Heterogeneity of neuroblastoma cell lines in insulin-like growth factor 1 receptor/Akt pathway-mediated cell proliferative responses

Insulin-like growth factor 1 receptor (IGF-1R) is critical for cancer cell proliferation; however, recent clinical anti-IGF-1R trials did not show clear clinical benefit in cancer therapy. We hypothesized that IGF-1R signaling-mediated proliferative response is heterogeneous in neuroblastoma (NB) cells, and analyzed the cell growth of 31 NB cell lines cultured in three different media, including Hybridoma-SFM medium (with insulin) and RPMI1640 with/without 10% FBS. Three growth patterns were found. In response to IGF and insulin, cell proliferation and Akt phosphorylation were upregulated in 13 cell lines, and suppressed by MK2206 (Akt inhibitor) and picropodophyllin (IGF-1R inhibitor). Interestingly, 3 of these 13 cell lines showed Akt self-phosphorylation and cell proliferation in RPMI1640; their proliferation was downregulated by anti-IGF-1 or anti-IGF-2 neutralizing antibody, suggesting the existence of an autocrine loop in the IGF-1R/Akt pathway. Eighteen NB cell lines did not proliferate in RPMI1640, even though Akt phosphorylation was upregulated by IGF and insulin. Based on the heterogeneous response of the IGF-1R/Akt pathway, the 31 NB cell lines could be classified into group 1 (autocrine IGF-mediated), group 2 (exogenous IGF-mediated) and group 3 (partially exogenous IGF-mediated) NB cell lines. In addition, group 3 NB cell lines were different from group 1 and 2, in terms of serum starvation-induced caspase 3 cleavage and picropodophyllin-induced G2/M arrest. These results indicate that the response of the IGF-1R/Akt pathway is an important determinant of the sensitivity to IGF-1R antagonists in NB. To our knowledge, this is the first report describing heterogeneity in the IGF-1R/Akt-mediated proliferation of NB cells.

Plant sterols as anticancer nutrients: evidence for their role in breast cancer

While many factors are involved in the etiology of cancer, it has been clearly established that diet significantly impacts one’s risk for this disease. More recently, specific food components have been identified which are uniquely beneficial in mitigating the risk of specific cancer subtypes. Plant sterols are well known for their effects on blood cholesterol levels, however research into their potential role in mitigating cancer risk remains in its infancy. As outlined in this review, the cholesterol modulating actions of plant sterols may overlap with their anti-cancer actions. Breast cancer is the most common malignancy affecting women and there remains a need for effective adjuvant therapies for this disease, for which plant sterols may play a distinctive role.

A multiplicity of anti-invasive effects of farnesyl transferase inhibitor SCH66336 in human head and neck cancer

Metastasis is a critical event in the progression of head and neck squamous cell carcinoma (HNSCC) and closely correlates with clinical outcome. We previously showed that the farnesyl transferase inhibitor SCH66336 has antitumor activities in HNSCC by inducing the secretion of insulin-like growth factor binding protein 3 (IGFBP-3), which in turn inhibits tumor growth and angiogenesis. In our study, we found that SCH66336 at a sublethal dose for HNSCC inhibited the migration and invasion of HNSCC cells. The inhibitory effect of SCH66336 was associated with the blockade of the IGF-1 receptor (IGF-1R) pathway via suppressing IGF-1R itself and Akt expression. Consistent with previous work, induction of IGFBP-3 by SCH66336 also contributed in part to the anti-invasive effect. SCH66336 treatment also reduced the expression and activity of the urokinase-type plasminogen activator (uPA) and matrix metalloproteinase 2 (MMP-2), both important regulators of tumor metastasis. The effect of SCH66336 on uPA activity was inhibited partly by knockdown of IGFBP-3 using small interfering RNA. The inhibitory effect of SCH66336 on migration or invasion was attenuated partly or completely by knockdown of IGFBP-3, Akt or IGF-1R expression, respectively. Our results demonstrate that the IGF-1R pathway plays a major role in the proliferation, migration and invasion of HNSCC cells, suggesting that therapeutic obstruction of the IGF-1R pathway would be a useful approach to treating patients with HNSCC.

Insulin-like growth factor-1 boosts the developing process of condylar hyperplasia by stimulating chondrocytes proliferation

OBJECTIVE

The etiology of Condylar hyperplasia (CH) of human temporomandibular joint (TMJ) remains largely unknown. Our previous study has demonstrated that enriched insulin-like growth factor-1(IGF-1) was expressed in the proliferation and hypertrophic layers of CH cartilage. Accordingly, this study was aimed to investigate whether IGF-1 regulates CH chondrocytes proliferation in condylar cartilage overgrowth and explore the molecular mechanism of IGF-1 involved in.

METHODS

Chondrocytes were isolated from 6 CH and 3 normal cartilage (NC) specimens and cultured in alginate beads or monolayer, treated with IGF-1 or specific inhibitors such as 7-[trans-3-[(azetidin-1-yl)methyl]cyclobutyl]-5-(3-benzyloxyphenyl)-7H-pyrrolo[2,3-d]pyrimidin-4-amine (NVP-AEW541), U0126, and LY294002. Thereafter, cellular proliferation capacity was evaluated by Cell Viability Analyzer (alginate beads culture) or 3-(4,5-dimethylthiazo(-2-yl)-2,5-diphenyltetrazolium bromide (MTT) (monolayer culture). Gene expression levels of IGF-1, IGF-1 receptor (IGF-1R), collagen type II, type X and those genes associated with proliferation were evaluated by realtime PCR. Protein levels of IGF-1 and IGF-1R synthesized by CH chondrocytes were accessed by enzyme-linked immunosorbent assay (ELISA) and western blotting.

RESULTS

CH chondrocytes enhanced cellular proliferation capacity and expressed significantly higher levels of messenger RNA (mRNA) and protein expressions of IGF-1 and IGF-1R, as compared with NC chondrocytes. Furthermore, enriched IGF-1 enhanced CH chondrocytes proliferation, up-regulated the expressions of specific genes associated with cellular proliferation and elevated the gene expression of collagen type II A1 (COL2A1). Besides, IGF-1-mediated CH chondrocytes proliferation mainly depended on the mitogen-activated protein kinase (MAPK)-ERK pathway.

CONCLUSIONS

IGF-1 promotes human TMJ cartilage overgrowth in the developing process of CH by enhancing chondrocytes proliferation via MAPK-ERK pathway.

Epidermal growth factor receptor and K-Ras mutations and resistance of lung cancer to insulin-like growth factor 1 receptor tyrosine kinase inhibitors

BACKGROUND

Most patients with nonsmall cell lung cancer (NSCLC) have responded poorly to epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors (TKIs). The authors investigated the involvement of insulinlike growth factor 1 receptor (IGF-1R) signaling in primary resistance to EGFR TKIs and the molecular determinants of resistance to IGF-1R TKIs.

METHODS

Phosphorylated IGF-1R/insulin receptor (pIGF-1R/IR) was immunohistochemically evaluated in an NSCLC tissue microarray. The authors analyzed the antitumor effects of an IGF-1R TKI (PQIP or OSI-906), either alone or in combination with a small-molecular inhibitor (PD98059 or U0126) or with siRNA targeting K-Ras or mitogen-activated protein kinase/extracellular signal-regulated kinase kinase (MEK), in vitro and in vivo in NSCLC cells with variable histologic features and EGFR or K-Ras mutations.

RESULTS

pIGF-1R/IR expression in NSCLC specimens was associated with a history of tobacco smoking, squamous cell carcinoma histology, mutant K-Ras, and wild-type (WT) EGFR, all of which have been strongly associated with poor response to EGFR TKIs. IGF-1R TKIs exhibited significant antitumor activity in NSCLC cells with WT EGFR and WT K-Ras but not in those with mutations in these genes. Introduction of mutant K-Ras attenuated the effects of IGF-1R TKIs on NSCLC cells expressing WT K-Ras. Conversely, inactivation of MEK restored sensitivity to IGF-TKIs in cells carrying mutant K-Ras.

CONCLUSIONS

The mutation status of both EGFR and K-Ras could be a predictive marker of response to IGF-1R TKIs. Also, MEK antagonism can abrogate primary resistance of NSCLC cells to IGF-1R TKIs.

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.

Ginsenoside Rp1 from Panax ginseng exhibits anti-cancer activity by down-regulation of the IGF-1R/Akt pathway in breast cancer cells

Cancer prevention is effective and reduces health care costs because cancer is often a preventable disease that can be affected by lifestyle factors. Therefore, researchers are interested in discovering natural compounds that have anticancer activities, such as delaying the development of cancer and preventing its progression. One such natural agent is ginseng (Panax ginseng), which is traditionally used in some parts of the world as a popular remedy for various diseases including cancer. We hypothesized that the ginsenoside Rp1, a component of ginseng, reduces cancer cell proliferation through inhibition of the insulin-like growth factor 1 receptor (IGF-1R)/Akt pathway. We first tested the efficacy of Rp1 against human breast cancer cell lines. Treatment with Rp1 inhibited breast cancer cell proliferation and inhibited both anchorage-dependent and -independent breast cancer cell colony formation. In addition, treatment with 20 μM Rp1 induced cycle arrest and apoptosis-mediated cell growth suppression. Our findings further indicated that Rp1 decreased the stability of the IGF-1R protein in breast cancer cells. Therefore, we suggest that Rp1 has potential as an anticancer drug and that IGF-1R is an important target for treatment and prevention of breast cancer.

Increased expression of insulin-like growth factor-1 receptor is correlated with tumor metastasis and prognosis in patients with osteosarcoma

BACKGROUND

The aim of this study was to investigate the association of insulin-like growth factor-1 receptor (IGF-1R) with metastasis and prognosis of osteosarcoma patients.

METHODS

RT-PCR and Western blot assays were performed to detect IGF-1R mRNA and protein expression in 26 osteosarcoma and noncancerous bone tissues. Immunohistochemistry was performed to analyze the correlation of IGF-1R expression in 84 osteosarcoma tissues with clinicopathological factors or survival of patients. Lentivirus-mediated RNA interference system was employed to downregulate IGF-1R expression and analyze the effects of IGF-1R downregulation on invasion and metastasis of osteosarcoma cells.

RESULTS

The relative levels of IGF-1R mRNA and protein expression were significantly higher in osteosarcoma tissues than in corresponding noncancerous bone tissues. The expression of IGF-1R protein was closely associated with surgical stage and distant metastasis of osteosarcoma patients. Osteosarcoma patients with high IGF-1R expression had poorer survival, and multivariate Cox analyses showed that high IGF-1R expression was an independent prognostic maker. Lentivirus-mediated targeting IGF-1R could significantly inhibit adhesion, migration, invasion, and metastasis of osteosarcoma cells, which might be correlated with of inactivation of Akt signaling pathway.

CONCLUSIONS

IGF-1R is an independent prognostic marker for osteosarcoma patients and increased expression of this molecular is correlated with metastasis of osteosarcoma.

Ghrelin and cachexia: will treatment with GHSR-1a agonists make a difference for patients suffering from chronic wasting syndromes?

Cachexia is a syndrome of wasting and anorexia that worsens the prognosis of many chronic diseases including cancer, chronic kidney disease, chronic heart disease and chronic obstructive pulmonary disease. Properties of the orexigenic hormone ghrelin-including appetite-stimulation, weight-gain production and increased cardiac output make it a logical treatment for cachexia. While endogenous ghrelin levels are increased in the setting of cachexia, treatment with ghrelin and other GHSR-1a agonists in animal models of cachexia and in humans with cachexia has demonstrated consistent effects of increased appetite and improved weight gain. These positive effects occur in multiple underlying diseases associated with cachexia and appear to be sustained over treatment duration of up to 12 weeks. The mechanism of action in producing these effects is likely related to stimulation of central appetite centers such as the central melanocortin system and to increased growth hormone release, though ghrelin's effects may also relate to decreased systemic inflammation and other direct and indirect actions. Questions regarding the long-term safety of ghrelin treatment are still unanswered, as is the important question of whether successful treatment of cachexia will improve the prognosis of the underlying disease itself.

Small is beautiful: insulin-like growth factors and their role in growth, development, and cancer

Insulin-like growth factors were discovered more than 50 years ago as mediators of growth hormone that effect growth and differentiation of bone and skeletal muscle. Interest of the role of insulin-like growth factors in cancer reached a peak in the 1990s, and then waned until the availability in the past 5 years of monoclonal antibodies and small molecules that block the insulin-like growth factor 1 receptor. In this article, we review the history of insulin-like growth factors and their role in growth, development, organism survival, and in cancer, both epithelial cancers and sarcomas. Recent developments regarding phase I to II clinical trials of such agents are discussed, as well as potential studies to consider in the future, given the lack of efficacy of one such monoclonal antibody in combination with cytotoxic chemotherapy in a first-line study in metastatic non-small-cell lung adenocarcinoma. Greater success with these agents clinically is expected when combining the agents with inhibitors of other cell signaling pathways in which cross-resistance has been observed.

Insulin-like growth factor-1 receptor and phosphorylated AKT-serine 473 expression in 132 resected thymomas and thymic carcinomas

BACKGROUND

Thymic malignancies are rare tumors. The insulin-like growth factor-1 (IGF-1)/IGF-1 receptor (IGF-1R) system is involved in the development of the thymus. IGF-1R expression in thymic epithelial malignancies is unknown.

METHODS

The authors investigated the expression of IGF-1R and phosphorylated AKT serine 473 (p-AKT) by using immunohistochemistry and examined the clinicopathologic correlations in a retrospective, single-institution surgical series of 132 patients with thymic epithelial malignancies.

RESULTS

Earlier disease stage, less aggressive histologic types, and complete resection were significant positive prognostic factors for disease-related survival and progression-free survival, and being a woman was a better prognostic factor for disease-related survival. IGF-1R and p-AKT protein levels were expressed in 20% and 36% of thymic tumors, respectively. Both markers were expressed more commonly in recurrent disease than in primary tumors, in more aggressive subtypes, and in more advanced disease stages. There was a trend toward better survival and progression-free survival in patients who were negative for IGF-1R or p-AKT expression in the whole series. When only the 91 primary tumors, IGF1R expression was associated with worse progression-free survival (P < .001).

CONCLUSIONS

The current retrospective analysis demonstrated that disease stage, tumor histology, sex, and resection type were major prognostic factors in the survival of patients with thymic malignancies. The expression levels of IGF-1R and p-AKT in thymic tumors suggested that IGF-1R is a potential target for treatment.

Ras-related protein 1 and the insulin-like growth factor type I receptor are associated with risk of progression in patients diagnosed with carcinoma in situ

Currently, there are no applied molecular markers to aid in predicting risk of carcinoma in situ (CIS) progression to invasive cancer, and therefore, all women diagnosed with CIS undergo surgery. Standard assessment of protein expression in fixed tissue by immunohistochemistry (IHC) is not quantitative and hence is not well suited for measuring biomarkers. In this study, we developed an original analytical method for IHC quantification. Using our novel image-based uniplex (IBU) method, quantitative protein profiling was performed on 90 samples of the breast (17 histologically normal tissues, 16 benign lesions, 15 CIS, and 42 invasive carcinomas). Differences between groups were assessed using analysis of variance (ANOVA) and mixed effects models. Measuring protein expression on a continuous scale revealed a significant increase in Ras-related protein 1 (Rap1) and the insulin-like growth factor type I receptor (IGF-IR) in conjunction with the presence of cancer invasion. Women with invasive cancers were four times more likely to have increased levels of Rap1 [odds ratio (OR) = 3.91; P = 0.0002] and IGF-IR (OR=4.33; P<0.0001) than women with non-invasive lesions. Furthermore, expression of both proteins was also increased significantly in CIS adjacent to invasive tumors compared with non-cancerous tissue. These novel findings of a significant up-regulation of Rap1 and IGF-IR in CIS progressing to invasive cancers warrant further investigation of Rap1 and IGF-IR together as a dual biomarker to aid in predicting risk of progression and ultimately providing non-surgical treatment options to those at lower risk.

Regulation of receptor for activated C kinase 1 protein by the von Hippel-Lindau tumor suppressor in IGF-I-induced renal carcinoma cell invasiveness

von Hippel-Lindau (VHL) tumor suppressor loss is associated with renal cell carcinoma (RCC) pathogenesis. Meanwhile, aberrant activation of the insulin-like growth factor-I (IGF-I) signaling has been implicated in the development of highly invasive metastatic RCC. However, the link between VHL inactivation and RCC invasiveness is still unexplored. Here, we show that the receptor for activated C kinase 1 (RACK1) is a novel pVHL-interacting protein. pVHL competes with IGF-I receptor (IGF-IR) for binding to RACK1 thus potentially modulating the downstream IGF-I signal pathway. Upon IGF-I stimulation, pVHL-deficient RCC cells exhibit increased RACK1/IGF-IR binding and increased IGF-IR tyrosine kinase activity. pVHL-deficient RCC cells also demonstrate elevated PI3K/Akt signaling and matrix metalloproteinase-2 activity that culminates in enhanced cellular invasiveness, which can be partially suppressed by RACK1 small interfering RNA. Domain mapping analysis showed that the pVHL α-domain and the RACK1 WD 6-7 domains are critical for the interaction. Additionally, the RACK1 expression level is not regulated by pVHL expression status, suggesting that pVHL modifies RACK1 functions independent of the VHL/elongin E3 ubiquitin ligase complex. Our data indicate that RACK1 serves as a direct mediator between loss of pVHL function and enhanced IGF-IR signaling pathway in RCC.

Study of growth factors and receptors in carcinoma ex pleomorphic adenoma

Carcinoma ex pleomorphic adenoma (CXPA) is a rare malignant salivary gland tumor derived from a pre-existing pleomorphic adenoma. It is a good model to study the evolution of carcinogenesis, starting with in situ areas to frankly invasive carcinoma. Growth factors are associated with several biological and neoplastic processes by transmembrane receptors. In order to investigate, by immunohistochemistry, the expression of some growth factors and its receptors [EGF receptor, fibroblast growth factor, fibroblast growth factor receptor 1, fibroblast growth factor receptor 2, hepatocyte growth factor, c-Met, transforming growth factor (TGF) beta1, TGFbetaR-II and insulin-like growth factor receptor 1] in the progression of CXPA, we have used ten cases of CXPA in several degrees of invasion- intracapsular, minimally and frankly invasive carcinoma- with only epithelial component. Slides were qualitatively and semi-quantitatively evaluated according to the percentage of stained tumor cells from 0 to 3 (0 = less than 10%; 1 = 10-25%; 2 = 25-50%; 3 = more than 50% of cells). Malignant epithelial cells starting with in situ areas showed stronger expression than luminal cells of pleomorphic adenoma for all antibodies. Most of the intracapsular, minimally and frankly invasive CXPA presented score 3. However, score 2 was more evident in the frankly invasive one. In small nests of invasive carcinoma, negative cells were observed probably indicating that the proliferative process is replaced by the invasive mechanism. Altogether this data infers that these factors may contribute to cell proliferation during initial phases of the tumor.

Inhibitory effects of andrographolide on migration and invasion in human non-small cell lung cancer A549 cells via down-regulation of PI3K/Akt signaling pathway

Lung cancer is the leading cause of death among cancers worldwide and non-small cell lung cancer (NSCLC) comprises more than 80% of lung cancer cases. Treatment options for patients with advanced NSCLC have evolved in the last decade with the advent of novel biological agents. Andrographolide, a diterpenoid lactone isolated from a traditional herbal medicine Andrographis paniculata, is known to have the potential to be developed as a chemotherapeutic agent. In order to understand the anti-cancer properties of andrographolide, we examined its effect on migration and invasion in human NSCLC A549 cells. The results of wound-healing assay and in vitro transwell assay revealed that andrographolide inhibited dose-dependently the migration and invasion of A549 cells under non-cytotoxic concentrations. Molecular data showed that the effect of andrographolide in A549 cells might be mediated via sustained inactivation of phosphatidylinositol 3-kinase (PI3K)/Akt signal involved in the up-regulation of matrix metalloproteinases (MMPs). Our results showed that andrographolide exerted an inhibitory effect on the activity and the mRNA and protein levels of MMP-7, but not MMP-2 or MMP-9. The andrographolide-inhibited MMP-7 expression or activity appeared to occur via activator protein-1 (AP-1) because of its DNA binding activity was suppressed by andrographolide. Additionally, the transfection of Akt over-expression vector (Akt1 cDNA) to A549 cells could result in an increase expression of MMP-7 concomitantly with a marked induction on cell invasion. These findings suggested that the inhibition on MMP-7 expression by andrographolide may be through suppression on PI3K/Akt/AP-1 signaling pathway, which in turn led to the reduced invasiveness of the cancer cells.

Myeloma cell growth inhibition is augmented by synchronous inhibition of the insulin-like growth factor-1 receptor by NVP-AEW541 and inhibition of mammalian target of rapamycin by Rad001

Multiple myeloma is still incurable. Myeloma cells become resistant to common drugs and patients eventually die of tumour progression. Therefore, new targets and drugs are needed immediately. NVP-AEW541 is a new, orally bioavailable small molecule inhibitor of the insulin-like growth factor-1 receptor (IGF-1R). Here, we show that NVP-AEW541 inhibits cell growth in myeloma cells at low concentrations in a time-dependent and a dose-dependent manner. Further experiments using the annexin-V-fluorescein isothiocyanate/propidium iodide assay revealed induction of apoptosis in common myeloma cell lines, but not in peripheral blood mononuclear cell from healthy donors. Stimulation of myeloma cells with IGF-1 led to a vast increase of cell growth and this was blocked by low doses of NVP-AEW541. Stimulation of myeloma cells with conditioned medium obtained from a 48-h-old HS-5 stromal cell culture was only partly blocked by NVP-AEW541. Western blotting experiments revealed that NVP-AEW541 decreased the phosphorylation status of P70S6 kinase and 4E-BP-1 but not of mammalian target of rapamycin (mTOR). Combined inhibition of IGF-1R and mTOR using the novel mTOR inhibitor Rad001 led to additive/synergistic increase of cell growth inhibition in multiple myeloma cells, which was accompanied by a stronger dephosphorylation of P70S6 kinase and 4E-BP-1. Taken together, we show that the combined inhibition of IGF-1R and mTOR by combining NVP-AEW541 and Rad001 is highly effective in multiple myeloma and might represent a potential new treatment strategy.

Lentivirus-mediated RNAi knockdown of insulin-like growth factor-1 receptor inhibits growth, reduces invasion, and enhances radiosensitivity in human osteosarcoma cells

The type 1 insulin-like growth factor receptor (IGF-1R) is essential for tumorigenicity, tumor proliferation, and protection from apoptosis. IGF-1R overexpression has been found in many human cancers including osteosarcoma. To explore its possibility as a therapeutic target for the treatment of osteosarcoma, lentivirus-mediated siRNA was employed to downregulate endogenous IGF-1R expression to study the function of IGF-1R in tumorigenesis and radioresistance of osteosarcoma cells. The IGF-1R expression was persistently and markedly reduced by lentivirus-mediated RNAi. Downregulation of IGF-1R expression in osteosarcoma cells significantly suppressed their growth rates in vitro and reduced the potential of tumorigenicity in vivo. Moreover, the specific downregulation arrested cells in G(0)/G(1) phase of cell cycle and also induced apoptosis which correlated with the activation of Caspase-3. Furthermore, we also observed that suppression of IGF-1R could reduce the invasiveness of osteosarcoma cells and enhance their radiosensitivity. Our study suggested that lentivirus-mediated RNAi silencing targeting IGF-1R could induce potent antitumor activity and radiosensitizing activity in human osteosarcomas.

Growth factor receptors signaling in glioblastoma cells: therapeutic implications

In this study, we investigated the protein expression of platelet-derived growth factor receptor (PDGFR), insulin like growth factor-1 receptor (IGF-1R), phosphatidylinositol 3-kinase (PI3-K) and extracellular signal-regulated kinase (ERK1/2) in five primary glioblastoma (GB), with a view to their possible use as therapeutic targets. Our results demonstrated that appreciable levels of these proteins could be detected in the analysed GB cell lines, except for a low level of PDGFR and ERK1/2 expression in one GB cell line. The small molecule inhibitors towards IGF-1R, PDGFR, PI3-K and ERK1/2 respectively, have only modest or no anti-tumour activity on GB cells and therefore their combination with other therapy modalities was analysed. The interaction between small inhibitors and radiation was mostly additive or sub-additive; synergistic interaction was found in five of forty analysed combinations. Our results showed that GB cells are in general resistant to treatment and illustrate the difficulties in predicting the treatment response in malignant gliomas.

Heterogeneity of receptor function in colon carcinoma cells determined by cross-talk between type I insulin-like growth factor receptor and epidermal growth factor receptor

This study identifies a novel cross-talk paradigm between the type I insulin-like growth factor receptor (IGF1R) and epidermal growth factor receptor (EGFR) in colon cancer cells. IGF1R activation by ligand exposure in growth factor-deprived cells induces Akt activation in the FET, CBS, and GEO colon cancer cell lines. Investigation of IGF1R-mediated signaling pathways using small interfering RNA approaches indicated that, as expected, phosphatidylinositol 3'-kinase (PI3K) was activated by IGF1R. Mitogen-activated protein kinase (MAPK) activity as reflected by phospho-extracellular signal-regulated kinase (ERK) induction was not significantly activated until later times following release of these cells from growth factor deprivation stress. The appearance of phospho-ERK was proximal to EGFR activation. Treatment of cells with the PI3K inhibitor LY294002 before release from stress resulted in a concentration-dependent loss of EGFR activation, whereas treatment with the MAPK inhibitor PD98059 did not block EGFR activation, indicating that EGFR activation was downstream of the IGF1R/PI3K pathway. PD98059 inhibition of MAPK was associated with a concentration-dependent reduction in EGFR-mediated phospho-ERK. EGFR inhibitor blocked induction of phospho-ERK, showing that MAPK activity was a consequence of EGFR-mediated signaling. On the other hand, a small-molecule IGF1R inhibitor, PQIP, blocked Akt phosphorylation. The divergent signaling functions of IGF1R and EGFR suggested the potential for synergism by a combination of therapy directed at the two receptors. Combination treatment with PQIP and EGFR inhibitor Tarceva resulted in synergistic effects as indicated by combination index analysis in all three cell lines tested.

Simultaneous blockade of AP-1 and phosphatidylinositol 3-kinase pathway in non-small cell lung cancer cells

c-Jun is a major constituent of AP-1 transcription factor that transduces multiple mitogen growth signals, and it is frequently overexpressed in non-small cell lung cancers (NSCLCs). Earlier, we showed that blocking AP-1 by the overexpression of a c-Jun dominant-negative mutant, TAM67, inhibited NSCLC cell growth. The phosphatidylinositol 3-kinase (PI3K)/Akt signal transduction pathway is important in transformation, proliferation, survival and metastasis of NSCLC cells. In this study, we used NCI-H1299 Tet-on clone cells that express TAM67 under the control of inducible promoter to determine the effects of inhibition of AP-1 and PI3K on cell growth. The PI3K inhibitor, LY294002, produced a dose-dependent inhibition of growth in H1299 cells and that inhibition was enhanced by TAM67. TAM67 increased dephosphorylation of Akt induced by LY294002 and reduced the TPA response element DNA-binding of phosphorylated c-Jun. TAM67 increased G1 cell cycle blockade induced by LY294002, which was partially associated with cyclin A decrease and p27^Kip1 accumulation. Furthermore, TAM67 and LY294002 act, at least additively, to inhibit anchorage-independent growth of the H1299 cells. These results suggest that AP-1 and PI3K/Akt pathways play an essential role in the growth of some NSCLC cells.

Impact of insulin-like growth factor type 1 receptor, epidermal growth factor receptor, and HER2 expressions on outcomes of patients with gastric cancer

PURPOSE

Expression levels of insulin-like growth factor type 1 receptor (IGF-IR), epidermal growth factor receptor (EGFR), and HER2 expressions have been linked to clinical outcomes in several solid tumors. However, the clinical significance of these biomarkers in gastric cancer (GC) remains unclear. This study was designed to delineate the clinical implications of these three biomarkers in GC.

EXPERIMENTAL DESIGN

The study group comprised 87 patients who underwent gastrectomy at National Cancer Center Hospital and subsequently received chemotherapy for recurrent or residual tumors. Using immunohistochemical techniques, we analyzed the expressions of IGF-IR, EGFR, and HER2 on formalin-fixed paraffin-embedded specimens of surgically removed primary tumors.

RESULTS

IGF-IR expression (defined as >10% membranous staining) was found in 67 tumors (77%), EGFR expression in 55 (63%), and HER2 expression in 16 (18%). Positive coexpression of IGF-IR and EGFR was found in 48 tumors (55%), that of IGF-IR and HER2 in 16 (18%), and that of EGFR and HER2 in 13 (15%). Multivariate survival analysis showed that IGF-IR-positive expression [hazard ratio (HR) 2.14, 95% confidence interval (95% CI) 1.20-3.82; P = 0.01], performance status 1 or 2 (HR 1.83, 95% CI 1.15-2.91; P = 0.01), and diffuse type tumors (HR 1.71; 95% CI 1.08-2.70; P = 0.02) were significant predictors of poor survival.

CONCLUSIONS

IGF-IR expression in surgical GC specimens, poor performance status, and diffuse type tumors are significant predictors of poor outcomes in patients with GC. Our data suggest that anti-IGF-IR strategies may prove valuable in such patients.

Clinical significance of insulin-like growth factor type 1 receptor and epidermal growth factor receptor in patients with advanced gastric cancer

OBJECTIVE

To better understand the clinical implications of insulin-like growth factor type 1 receptor (IGF-1R), epidermal growth factor receptor (EGFR) and HER2 expressions in gastric cancer (GC).

METHODS

The study group comprised 86 patients who received first-line chemotherapy for advanced GC at the National Cancer Center Hospital. Using laser-captured microdissection and a real-time RT-PCR assay, we quantitatively evaluated mRNA levels of IGF-1R, EGFR and HER2 in paraffin-embedded cancer specimens of surgically removed primary tumors.

RESULTS

In univariate analysis of the study group as a whole, patients with low expression of both IGF-1R and EGFR (n = 13) had a significantly longer overall survival than the other patients (n = 51; median, 24.6 vs. 12.8 months; log-rank p = 0.013). Multivariate survival analysis demonstrated that high EGFR expression [hazard ratio, HR: 2.94 (95% confidence interval, CI: 1.40-6.17), p = 0.004] and poor performance status [HR: 1.96 (95% CI: 1.12-3.42), p = 0.018] were significant predictors of poor survival. In patients given first-line S-1 monotherapy (n = 29), low IGF-1R (p = 0.002) and low EGFR (p = 0.035) gene expression correlated with a better response, without a significant prolongation of survival.

CONCLUSION

Our data warrant further investigations on the strategy of co-targeting IGF-1R and EGFR in GC.

[Molecular pathogenesis of hepatocellular carcinoma: new therapeutic approaches and predictive pathology]

Hepatocellular carcinoma is one of the most prevalent malignancies worldwide and its incidence is increasing. Multimodal strategies directed towards this carcinoma include primary (e.g. immunisation) and secondary (e.g. antiviral therapy) prevention, surgical approaches, novel specific systemic therapies (targeted therapy), and the treatment of comorbidity (cirrhosis). New molecular approaches are currently under development. These tackle several specific targets, with pathology being challenged in many aspects: experimental evaluation, the development of valid tumor-relevant diagnostic tests as well as morphological evaluation in the context of clinical studies, and finally in routine diagnosis.

The insulin-like growth factor-I receptor inhibitor NVP-AEW541 provokes cell cycle arrest and apoptosis in multiple myeloma cells

Multiple myeloma (MM) is a B-cell malignancy characterized by accumulation of monoclonal plasma cells in the bone marrow (BM). Despite recent advances in the treatment, MM represents an incurable disease for which development of new therapies is required. We report the antimyeloma effect of NVP-AEW541, a small molecule that belongs to the pyrrolo[2,3-d]pyrimidine class, identified as a selective inhibitor of the insulin-like growth factor-I receptor (IGF-IR) in vitro kinase activity. NVP-AEW541 had a potent cytotoxic effect on fresh cells and in a murine MM model. NVP-AEW541 partially abrogated the proliferative advantage conferred by the coculture with BM stromal cells and the presence of growth factors produced by the BM microenvironment. In addition, NVP-AEW541 potentiated the action of drugs, such as bortezomib, lenalidomide, dexamethasone or melphalan. Moreover the triple combination of NVP-AEW541, dexamethasone and bortezomib resulted in a significant increase in growth inhibition. Mechanistic studies indicated that NVP-AEW541 provoked a marked cell cycle blockade accompanied by pRb downregulation. Interestingly, NVP-AEW541 increased the levels of p27 associated with a reduction in the CDK2 activity. Finally, NVP-AEW541 induced cell death through caspase-dependent and -independent mechanisms. All these data, suggest the potential effect of IGF-IR kinase inhibitors as therapeutic agents for MM patients.

RAV12 Accelerates the Desensitization of Akt/PKB Pathway of Insulin-like Growth Factor I Receptor Signaling in COLO205

RAV12 is a high-affinity immunoglobulin G(1) (IgG(1)) chimeric antibody recognizing an N-linked carbohydrate epitope expressed on a number of human carcinomas and adenocarcinomas. RAV12 is efficacious in treating colon, gastric, and pancreatic tumors in xenograft models in vivo. Insulin-like growth factor-I receptor (IGF-IR) is a protein widely overexpressed in tumor-derived cell lines that promotes cell survival and prevents apoptosis. We found the RAV12 epitope (RAAG12) decorated the IGF-IR proteins of RAV12-responsive cell lines such as COLO201, COLO205, and SNU-16. Here, we report findings of IGF-IR signaling manipulation by RAV12. We found that RAV12 caused a significantly accelerated IGF-I-mediated IGF-IR phosphorylation and desensitization in COLO205. We also observed significant changes in some of the major downstream signaling components of IGF-IR. Data suggested that RAV12 treatment accelerated the desensitization of Akt/PKB through IRS1, and such activation could be attenuated by Tyrphostin AG538 (IGF-IR inhibitor), LY294002, or Wortmannin (phosphoinositide-3-kinase inhibitor). Furthermore, RAV12-inhibited IGF-I stimulated COLO205 growth, and the inhibition could be significantly augmented by mitogen-activated protein kinase inhibitor.

Inhibition of hepatocellular carcinoma growth by antisense oligonucleotides to type I insulin-like growth factor receptor in vitro and in an orthotopic model

AIM

The type I insulin-like growth factor receptor (IGF-IR) is overexpressed in many tumors including human hepatocellular carcinoma (HCC). It is a critical signaling molecule for tumor cell proliferation and survival. In the present study, IGF-IR expression was down-regulated by phosphorothioate antisense oligonucleotides (AS[S]ODN) to evaluate their specific effects on growth of hepatoma cells in vitro and in vivo.

METHODS

HepG2 cells were transfected with different doses of AS[S]ODN, sense [S]ODN, mismatch [S]ODN, or Lipofectin for 72 h, and cell proliferation was analyzed by MTS assay. In vivo, an orthotopic transplant model of HCC was established in nude mice, which were then injected with AS[S]ODN, sense [S]ODN, 5-fluorouracil or saline. At the endpoint of treatment, the tumors were excised and evaluated.

RESULTS

Compared to sense and mismatched oligonucleotides, AS[S]ODN targeting to IGF-IR mRNA significantly inhibited hepatoma cell lines HepG2 proliferation and IGF-IR expression at both mRNA and protein levels. The in vivo results showed that systemic treatment also resulted in significant inhibition in tumor growth. Tumor growth in mice treated with AS[S]ODN (50 and 75 mg/kg per day) was significantly inhibited (71.81% and 61.74%, respectively) compared to the saline-treated group (P < 0.01) in a dose-dependent manner. The antitumor effect of IGF-IR AS[S]ODN was associated with down-regulation of IGF-IR in tumor xenografts. Furthermore, IGF-IR AS[S]ODN prevented liver recurrence tumor growth and metastasis in the lung, showing a dose-dependent response. The level of serum alpha-fetoprotein in AS[S]ODN-treated groups was also decreased in a dose-dependent manner, and a good correlation was observed between tumor volume and serum alpha-fetoprotein concentration.

CONCLUSIONS

These data suggest that IGF-IR AS[S]ODN can effectively and specifically inhibit HCC growth in vitro and in vivo. Blockage of IGF-IR expression could be a promising therapeutic approach for the management of patients with HCC.

Antimetastatic activity of insulin-like growth factor binding protein-3 in lung cancer is mediated by insulin-like growth factor-independent urokinase-type plasminogen activator inhibition

Insulin-like growth factor binding protein-3 (IGFBP-3), a major IGF-binding protein in human serum, regulates the growth of non-small cell lung cancer (NSCLC) cells through IGF-dependent and IGF-independent mechanisms. However, the role of IGFBP-3 in lung cancer metastasis is not well known. In the present study, we showed that noncytotoxic doses of adenoviral or recombinant IGFBP-3 significantly decreased the migration and invasion of H1299 and A549 NSCLC cells. Furthermore, treatment of human lung fibroblasts with recombinant IGFBP-3 suppressed their ability to stimulate the invasion of H1299 cells. Overexpression of IGFBP-3 markedly reduced lung metastasis of A549 cells in an experimental animal model system and prolonged the survival time of the animals. Urokinase-type plasminogen activator (uPA) inhibitor treatment or uPA small interfering RNA transfection of A549 and H1299 cells resulted in a significant decrease in invasion. Corresponding ELISA, Western blot, gelatin zymogram, and semiquantitative reverse transcription-PCR analyses revealed that IGFBP-3 reduced the expression of uPA mRNA through IGF-independent mechanisms. The specific role of uPA in anti-invasive activity of IGFBP-3 was further confirmed in NSCLC cells, in which uPA expression/activity was suppressed by the transfection with synthetic small interfering RNA or by the treatment with uPA inhibitor or induced by the infection with an adenoviral vector. IGFBP-3 also decreased the expression/activity of matrix metalloproteinase-2 through IGF-dependent but uPA-independent pathways. Taken together, our data suggest that IGFPB-3 effectively block uPA- and matrix metalloproteinase-2-stimulated invasion pathways, ultimately reducing lung cancer cell metastasis. Our findings indicate that IGFBP-3 may be a promising anti-invasive and antimetastatic therapeutic agent in lung cancer.

ATP non-competitive IGF-1 receptor kinase inhibitors as lead anti-neoplastic and anti-papilloma agents

The insulin-like growth factor-1 receptor (IGF-1 receptor) is a receptor tyrosine kinase, highly homologous to the insulin receptor. In contrast to the insulin receptor, which is mostly involved in metabolic pathways, the IGF-1 system plays a pivotal role in normal and neoplastic cell growth through anti-apoptotic, proliferative and metastatic pathways. Furthermore, IGF-1 receptor over-activation is found to correlate with a variety of tumors, such as breast cancer, prostate cancer, hematological malignancies, colorectal cancer and other proliferative diseases, such as psoriasis and papilloma. In addition, accumulating evidence implies that blockade of IGF-1 receptor activity causes reversal of tumor progression in cell lines as well as in animal tumor models. Because of the central role the IGF-1 receptor plays in oncogenic maintenance and metastatic processes, it is a highly appropriate target for anti-cancer agents. Here we report on a novel substrate-mimic family of IGF-1 receptor inhibitors. These compounds are tertiary aromatic amines, non-competitive with ATP and possess high affinity towards the IGF-1 receptor. The most potent compound, SBL02 inhibited the IGF-1 receptor with an IC(50) of 170 nM in a cell-free kinase assay and was found to inhibit IGF-1 receptor auto-phosphorylation and substrate phosphorylation at the low micromolar range in cellular assays. SBL02 also blocks the formation of colonies in soft agar by cancer cells and inhibits the growth of keratinocytes and of HPV16 immortalized keratinocytes. This new family of non-ATP competitive, IGF-1 receptor inhibitors can serve as a lead for the development of anti-cancer, anti-psoriatic and anti-papilloma agents.

Comparison of three approaches for inhibiting insulin-like growth factor I receptor and their effects on NSCLC cell lines in vitro

The insulin-like growth factor-1 receptor (IGF-1R) mitogenic signaling mediates malignant cell survival by many complex and redundant pathways. This study compared the effects of IGF-1R inhibition on viability and apoptosis of two NSCLC cell lines, using three different methods for the impairment of IGF-1R function: (IR3, an anti-IGF-1R antibody; tyrphostin AG1024, a tyrosine kinase inhibitor (TKI) and IGF-1R-small interfering RNA (siRNA). IGF-1R inhibition led to a decrease of cell survival and induced apoptosis in a manner depending on the approach used for the receptor inhibition. To find an explanation, we analyzed the effects of these treatments on three major antiapoptotic pathways evoked by IGF-1R signaling: IRS-1, Shc and 14.3.3-dependent mitochondrial translocation of Raf-1 kinase (mitRaf). (IR3 downregulated IRS-1 phosphorylation in A549 cells and Shc phosphorylation in U1810 cells. While in A549 cells AG1024 treatment decreased both IRS-1 and Shc phosphorylation, in U1810 cells the IRS-1 phosphorylation was only slightly affected and the Shc phosphorylation drastically downregulated. Neither (IR3 nor AG1024 had any effect on Raf-1 kinase translocation. Irrespective of the cell line, IGF-1R-siRNA treatment induced downregulation of both IRS-1 and Shc phosphorylation coupled with the abrogation of mitRaf. In addition, the IGF-1R-siRNA proved to be the most potent inducer of apoptosis suggesting that more than one antiapoptotic pathway in IGF-1R signaling should be inhibited to effectively induce apoptosis in lung cancer cells.

Suppression of type 1 Insulin-like growth factor receptor expression by small interfering RNA inhibits A549 human lung cancer cell invasion in vitro and metastasis in xenograft nude mice

Cancer invasion and metastasis, involving a variety of pathological processes and cytophysiological changes, contribute to the high mortality of lung cancer. The type 1 insulin-like growth factor receptor (IGF-1R), associated with cancer progression and invasion, is a potential anti-invasion and anti-metastasis target in lung cancer. To inhibit the invasive properties of lung cancer cells, we successfully down-regulated IGF-1R gene expression in A549 human lung cancer cells by small interfering RNA (siRNA) technology, and evaluated its effects on invasion-related gene expression, tumor cell in vitro invasion, and metastasis in xenograft nude mice. A549 cells transfected with a plasmid expressing hairpin siRNA for IGF-1R showed a significantly decreased IGF-1R expression at the mRNA level as well as the protein level. In biological assays, transfected A549 cells showed a significant reduction of cell-matrix adhesion, migration and invasion. Consistent with these results, we found that down-regulation of IGR-1R concomitantly accompanied by a large reduction in invasion-related gene expressions, including MMP-2, MMP-9, u-PA, and IGF-1R specific downstream p-Akt. Direct tail vein injections of plasmid expressing hairpin siRNA for IGF-1R significantly inhibited the formation of lung metastases in nude mice. Our results showed the therapeutic potential of siRNA as a method for gene therapy in inhibiting lung cancer invasion and metastasis.

Early effects of imatinib mesylate on the expression of insulin-like growth factor binding protein-3 and positron emission tomography in patients with gastrointestinal stromal tumor

BACKGROUND

Imatinib has demonstrated marked clinical efficacy against gastrointestinal stromal tumor (GIST). Microarray technology, real-time polymerase chain reaction (PCR) validation, and fluorodeoxyglucose-positron emission tomography (FDG-PET) imaging were used to study the early molecular effects of imatinib antitumor activity in GIST.

METHODS

After exposure of sensitive and resistant sarcoma cell lines to imatinib for 24 to 48 hours, the changes in gene expression were evaluated using a 1146 unique pathway array with Western blot validation. Real-time PCR was used to confirm changes in gene expression in human GIST samples (preimatinib biopsy and postimatinib surgical specimen after 3-7 days of therapy). FDG-PET was performed to correlate radiographic findings with the effects of imatinib on gene expression in GIST.

RESULTS

In all, 55 genes demonstrated a > or = 2-fold change after imatinib treatment of the GIST882 cells. Among these genes there was up-regulation of insulin-like growth factor binding protein-3 (IGFBP-3), a protein that modulates proliferation and apoptosis. Western blot analysis confirmed the increase of IGFBP-3 only in imatinib-sensitive GIST882 cells. Up to a 7-fold induction (49% mean increase; P = .08) of IGFBP-3 mRNA was found in tumor samples from patients with low residual FDG uptake, whereas there was an up to 12-fold reduction (-102% mean decrease; P = .03) in IGFBP-3 in those patients with high residual FDG uptake after imatinib therapy.

CONCLUSIONS

In the current study, imatinib appears to regulate numerous genes and specifically induces IGFBP-3 in GIST cells and tumor samples. IGFBP-3 levels also were found to be inversely correlated with residual FDG uptake in GIST patients early in imatinib therapy. These initial observations suggest that IGFBP-3 is an important early marker of antitumor activity of imatinib in GIST.

Targeting the insulin-like growth factor axis as a cancer therapy

The insulin-like growth factor (IGF) axis has been implicated in malignant transformation and in tumor cell biology. Human population studies have demonstrated that high levels of circulating IGF-I are associated with an increased risk of certain malignancies. Many model systems show that IGFs stimulate tumor cell proliferation, survival and metastasis. In a new era of anticancer treatments aimed at tumor-specific targets, efforts are in progress for the development of novel anti-IGF therapies. Disrupting type I IGF-receptor (IGF-IR) function in vitro and in vivo results in tumor growth inhibition in several model systems. Antireceptor therapies in particular have provided encouraging results leading to the approval of the first Phase I human clinical trial targeting IGF-IR. Additional methods to decrease levels of circulating IGF-I and II have also been developed. In principle, a benefit of targeted therapies could be their relative lack of toxicity compared with conventional chemotherapy. Anti-IGF-IR therapies, however, raise theoretical concerns for the development of serious side effects, including diabetes. As targeted therapies against the IGF axis continue to be developed, efforts will need to be made to minimize the side effects that result from blocking normal ligand and receptor-induced functions.

Effect of blocking IGF-I receptor on growth of human hepatocellular carcinoma cells

AIM: To study the expression level and localization of insulin-like growth factor -I receptor (IGF-IR) in HepG2 cells and Chang liver cells, and to observe the effect of anti-IGF-IR monoclonal antibody (αIR3) on the growth of HepG2 cells.

METHODS: The expression of IGF-IR in HepG2 cells and Chang liver cells was detected by immunohistochemistry. The influences of αIR3 on proliferation and apoptosis were examined by the 3- (4, 5-dimethylthiazol-2-yl)-2, 5- diphenyltetrazolium bromide (MTT) assay and electron microscopy, respectively. Flow cytometry (FCM) was applied for the analysis of cell cycle and apoptosis was observed under electron microscope.

RESULTS: IGF-IR was located in the membranes of both HepG2 and Chang liver cell lines, and the expression level of IGF-IR was higher in HepG2 cells than in Chang liver cells. Treated with 0.1 μg/mL αIR3 for 48 h in vitro, the cell growth index (GI) of HepG2 cells was significantly higher than that of control (103.41% vs 100%, P < 0.01). However, the αIR3 for 24 h at final concentration of 4.0 μg/mL made the GI of HepG2 cells lower than that of control (93.37% vs 100%, P < 0.01). Compared with control, treated with αIR3 for 48 h at final concentrations ranging from 1.0 μg/mL to 4.0 μg/mL markedly reduced the GIs of HepG2 cells (97.63%, 97.16%, 95.13%, 92.53% vs 100%, P < 0.05 or P < 0.01), treated with αIR3 for 72 h at final concentrations ranging from 0.2 μg/mL to 4.0 μg/mL decreased the GIs of HepG2 cells obviously (95%, 91.63%, 90.77%, 89.84%, 88.51% vs 100%, P < 0.01), and treated with αIR3 for 96 h at final concentrations ranging from 0.5 μg/mL to 4.0 μg/mL made GIs of HepG2 cells lower significantly (88.86%, 83.97%, 79.81%, 77.24%, 70.51% vs 100%, P < 0.05 or P < 0.01). Moreover, treated with αIR3 from 24 h to 96 h at final concentrations ranging from 0.2 μg/mL to 4.0 μg/mL reduced the GI of HepG2 cells from 97.63% to 70.51% in a dose- and time-dependent manner. Also, αIR3 treatment for 72 h at final concentration from 0.5 μg/mL to 2.0 μg/mL increased the proportion of G₀/G₁ phase cells(61.73%, 67.1%, 83.7%,76.87% vs 44.47%, P < 0.01) and significantly decreased that of S phase cells(28.63%, 25.13%, 15.63%, 23.13% vs 53.17%, P < 0.01), in contrast to the proportion of G₂/M phase cells. The apoptotic rates of HepG2 cells were increased more than that of control (7.83%, 16.13%, 21.1%, 37.73% vs 4.13%, P < 0.01).

CONCLUSION: The malignant cell phenotype of human hepatocarcinoma cell is related to overexpression of IGF-IR. The blockage of IGF-IR with αIR3 may contribute to the inhibition of proliferation and induction of apoptosis in HepG2 cells.

Insulin-like growth factor receptor 1 (IGFR-1) is significantly associated with longer survival in non-small-cell lung cancer patients treated with gefitinib

BACKGROUND

The aim of the study was to assess whether loss of PTEN and expression of insulin-like growth factor receptor 1 (IGFR-1) could be responsible for intrinsic resistance to the tyrosine kinase inhibitor (TKI) gefitinib.

PATIENTS AND METHODS

One hundred and twenty-four gefitinib-treated patients with advanced non-small-cell lung cancer (NSCLC) were analyzed for PTEN and IGFR-1 expression by immunohistochemistry.

RESULTS

IGFR-1 was evaluated in 77 patients and resulted positive in 30 (39.0%). IGFR-1 expression was not significantly associated with clinical or biological characteristics. No difference in response to gefitinib treatment (16.7% versus 12.8%, P = 0.74) and time to progression (2.6 versus 3.06 months, P = 0.83) was observed between IGFR-1+ and IGFR-1-. Median survival was significantly longer in IGFR-1+ patients (17.8 versus 7.3 months, P = 0.013). PTEN expression was successfully evaluated in 93 cases. Loss of PTEN was detected in 19 tumors (20.4%) and was not associated with any clinical or biological characteristic. No difference in terms of response, time to progression and survival was observed between PTEN+ and PTEN- patients. In multivariable analysis IGFR-1 negative status was significantly associated with higher risk of death (hazard ratio 2.21, P = 0.012).

CONCLUSIONS

IGFR-1 expression and loss of PTEN are not associated with intrinsic resistance to gefitinib. Clinical relevance of these two biomarkers as determinant for acquired resistance, and the prognostic role of IGFR-1 expression in patients not exposed to TKIs should be evaluated further.

The insulin-like growth factor system and colorectal cancer: clinical and experimental evidence

OBJECTIVE

The aim of this review is to clarify the involvement of the insulin-like growth factor (IGF) system in the development of colorectal malignancy.

MATERIALS AND METHODS

Medline searches were used to identify key articles relating the IGF system with the development of colorectal cancer.

RESULTS

The IGF system has been linked to colorectal malignancy by a convergence of data from epidemiological, clinical and laboratory-based sources.

CONCLUSION

Further work is needed to characterise the IGF system expression in the colon. Such clarification could lead to the identification of targets that can be manipulated for clinical advantage.

The insulin-like growth factor-1 receptor inhibitor PPP produces only very limited resistance in tumor cells exposed to long-term selection

The cyclolignan PPP was recently demonstrated to inhibit the activity of insulin-like growth factor-1 receptor (IGF-1R), without affecting the highly homologous insulin receptor. In addition, PPP caused complete regression of xenografts derived from various types of cancer. These data highlight the use of this compound in cancer treatment. However, a general concern with antitumor agents is development of resistance. In light of this problem, we aimed to investigate whether malignant cells may develop serious resistance to PPP. After trying to select 10 malignant cell lines, with documented IGF-1R expression and apoptotic responsiveness to PPP treatment (IC50s less than 0.1 microM), only two survived an 80-week selection but could only tolerate maximal PPP doses of 0.2 and 0.5 microM, respectively. Any further increase in the PPP dose resulted in massive cell death. These two cell lines were demonstrated not to acquire any essential alteration in responsiveness to PPP regarding IGF-1-induced IGF-1R phosphorylation. Neither did they exhibit any increase in expression of the multidrug resistance proteins MDR1 or MRP1. Consistently, they did not exhibit decreased sensitivity to conventional cytostatic drugs. Rather, the sensitivity was increased. During the first half of the selection period, both cell lines responded with a temporary and moderate increase in IGF-1R expression, which appeared to be because of an increased transcription of the IGF-1R gene. This increase in IGF-1R might be necessary to make cells competent for further selection but only up to a PPP concentration of 0.2 and 0.5 microM. In conclusion, malignant cells develop no or remarkably weak resistance to the IGF-1R inhibitor PPP.

Insulin-like growth factor-I receptor signaling in tamoxifen-resistant breast cancer: a supporting role to the epidermal growth factor receptor

There is considerable evidence that the epidermal growth factor receptor (EGFR) and IGF-I receptor (IGF-IR) cross-talk in breast cancer cells. In the present study, we have examined whether EGFR/IGF-IR cross-talk exists in EGFR-positive tamoxifen-resistant variants of MCF-7 (Tam-R) and T47D (T47D-R) breast cancer cell lines. Although Tam-R cells expressed reduced IGF-IR protein levels compared with their wild-type MCF-7 counterparts, phosphorylated IGF-IR protein levels were equivalent in the two cell lines under basal growth conditions, possibly as a consequence of increased IGF-II expression in Tam-R cells. IGF-II activated both IGF-IR and EGFR in Tam-R cells, whereas only activation of IGF-IR was observed in wild-type cells. In contrast, epidermal growth factor rapidly induced EGFR, but not IGF-IR, phosphorylation in Tam-R cells. IGF-II promoted direct association of c-SRC with IGF-IR, phosphorylated c-SRC, and increased EGFR phosphorylation at tyrosine 845, a c-SRC-dependent phosphorylation site. Pretreatment with either AG1024 (IGF-IR-specific inhibitor) or an IGF-II neutralizing antibody inhibited basal IGF-IR, c-SRC, and EGFR phosphorylation, and AG1024 significantly reduced Tam-R basal cell growth. The c-SRC inhibitor SU6656 also inhibited growth, reduced basal and IGF-II-induced c-SRC and EGFR phosphorylation, and blocked EGFR activation by TGFalpha. Similarly, in T47D-R cells, AG1024 and SU6656 inhibited basal and IGF-II-induced phosphorylation of c-SRC and EGFR, and SU6656 reduced TGFalpha-induced EGFR activity. These results suggest the existence of a unidirectional IGF-IR/EGFR cross-talk mechanism whereby IGF-II, acting through the IGF-IR, regulates basal and ligand-activated EGFR signaling and cell proliferation in a c-SRC-dependent manner in Tam-R cells. This cross-talk between IGF-IR and EGFR is not unique to Tam-R cells because this mechanism is also active in a tamoxifen-resistant T47D-R cell line.