Significant increase in hEGF uptake is correlated with formation of EGFR dimers induced by the EGFR tyrosine kinase inhibitor gefitinib

Purpose

The epidermal growth factor receptor (EGFR) tyrosine kinase inhibitor gefitinib (ZD1839, Iressa) is approved for cancer treatment. We investigated whether gefitinib treatment can enhance human EGF (hEGF) uptake in vitro, thereby increasing the potential of hEGF as a vehicle for EGFR-targeted therapy.

Methods

Western blotting was used to detect the effect of gefitinib on EGFR signaling. Different EGFR-expressing tumor cells (SCC-1, 22B, A549, and HT-29) were pretreated with gefitinib, and then with ¹²⁵I-hEGF or ¹²⁵I-Vectibix (an anti-EGFR monoclonal antibody). Cell-associated activity was then measured. A cross-linking assay detected increased EGFR dimer formation in gefitinib-treated cells.

Results

Total EGFR levels were not changed, but EGFR phosphorylation was reduced in cells pretreated with gefitinib. Gefitinib mediated formation of EGFR dimers; binding of ¹²⁵I-hEGF to cells pretreated with gefitinib significantly increased. In contrast, binding of ¹²⁵I-Vectibix to tumor cells did not increase. Although total EGFR levels did not increase, binding of hEGF to EGFR + tumors was significantly enhanced after gefitinib treatment, because of increased hEGF binding to gefitinib-induced EGFR dimers.

Conclusion

These results suggest that hEGF could enhance EGFR-targeting when used with gefitinib.     

Concomitant high gene copy number and protein overexpression of IGF1R and EGFR negatively affect disease-free survival of surgically resected non-small-cell-lung cancer patients

Background

Insulin-like growth factor 1 receptor (IGF1R) represents a novel molecular target in non-small-cell-lung cancer (NSCLC). IGF1R and epidermal growth factor receptor (EGFR) activation are essential to mediate tumor cell survival, proliferation, and invasion. This study investigates the prognostic role of IGF1R and EGFR in surgically resected NSCLC.

Materials and methods

IGF1R and EGFR copy number gain (CNG) were tested by fluorescence in situ hybridization (FISH) and protein expression by immunohistochemistry (IHC) in 125 stage I–II–IIIA NSCLC patients.

Results

Fourty-six tumors (40.3 %) were IGF1R FISH-positive (FISH+), and 76 (67.2 %) were EGFR FISH+. Tumors with concomitant IGF1R/EGFR FISH+ were observed in 34 cases (30.1 %). IGF1R and EGFR FISH+ were associated with SCC histology (p = 0.01 and p = 0.04, respectively). IGF1R and EGFR protein over-expression (IHC+) were detected in 45 (36.0 %) and 69 (55.2 %) cases, respectively. Tumors with concomitant IGF1R/EGFR IHC+ were detected in 31 (24.8 %) patients. IGF1R/EGFR FISH+ and IGF1R/EGFR IHC+ were significantly associated (χ² = 4.02, p = 0.04). Patients with IGF1R/EGFR FISH+ and IGF1R/EGFR IHC+ were associated with shorter disease-free survival (DFS) (p = 0.05 and p = 0.05, respectively). Patients with concomitant IGF1R/EGFR FISH+/IHC+ had a worse DFS and overall survival (p = 0.005 and p = 0.01, respectively). The multivariate model confirmed that IGF1R/EGFR FISH+/IHC+ (hazard ratio (HR), 4.08; p = 0.01) and tumor stage (II–III vs I) (HR, 4.77; p = 0.003) were significantly associated with worse DFS.

Conclusions

IGF1R/EGFR FISH+ correlates with IGF1R/EGFR IHC+. IGF1R/EGFR FISH+/IHC+ is an independent negative prognostic factor for DFS in early NSCLC. These features may have important implications for future anti-IGF1R therapeutic approaches.     

CUG-binding protein 1 (CUGBP1) expression and prognosis of non-small cell lung cancer

Background and aims

Non-small cell lung cancer (NSCLC) is the leading cause of cancer mortality worldwide. As CUGBP1 may also play a great role in tumor genesis and deterioration, the purpose of this study was to detect the expression of CUGBP1 mRNA and CUGBP1 and assess the prognostic significance of CUGBP1 in NSCLC.

Methods

Expression of CUGBP1 mRNA and CUGBP was detected by Semi-quantitative PCR and Immunohistochemistry, respectively, from 57 NSCLC patients. The percentage of CUGBP1 mRNA and CUGBP1 expression was correlated with clinical characteristics using χ ² test. The prognostic significance was assessed by univariate and multivariate analyses in the Cox hazard model.

Results

The expression of CUGBP1 mRNA and CUGBP1 was over-expressed in cancer group and was correlated with TNM stage and Differentiation. By both univariate and multivariate survival analyses, CUGBP1 expression (P = 0.0074, HR = 3.701, 95 % CI 1.420–9.648), TNM-stage (HR = 4.043, 95 % CI 2.098–7.794) and age (HR = 3.207, 95 % CI 1.544–6.664) were noted to be independent indicators of a shorter postsurgical survival.

Conclusions

The expression of CUGBP1 independently predicted a shorter postsurgical survival in NSCLC.     

Epidermal growth factor receptor (EGFR) mRNA levels and protein expression levels in primary colorectal cancer and corresponding liver metastases

Purpose

High expression levels of EGFR mRNA are reported to be associated with a higher response probability in epidermal growth factor receptor (EGFR) targeted drugs. Our aim was to determine how EGFR gene expression levels in primary colorectal cancer (CRC) were related to those in liver metastases.

Methods

31 pairs of primary CRC and corresponding liver metastases were analyzed. Gene expression level was measured using real-time RT-PCR.

Results

No significant difference was observed between median mRNA expression levels of EGFR in primary cancer and those in corresponding liver metastases (P = 0.99). When matched tissue sets were compared on an individual basis, there was a significant correlation for EGFR mRNA expression between primary cancer and corresponding liver metastases (r _s = 0.78, P < 0.0001).

Conclusions

A good prediction of EGFR mRNA levels in liver metastases can be obtained by measuring those in the primary CRC.     

Phase II study of S-1 monotherapy in patients with previously treated, advanced non-small-cell lung cancer

Background

In this phase II clinical trial, we evaluated the efficacy and safety of S-1 monotherapy in patients with previously treated advanced non-small-cell lung cancer (NSCLC). We also measured plasma concentrations of 5-fluorouracil (5-FU) and 5-chloro-2,4-dihydroxypyridine components of S-1 and examined correlation with effectiveness and toxicity.

Methods

S-1 was given orally at a dose of 80?mg/m²/day for 14 consecutive days, followed by a 7-day rest period. This treatment course was repeated until disease progression or intolerable toxicity.

Results

We enrolled 30 patients. The response rate was 26.7% (8/30), and the disease control rate was 70% (21/30). Median progression-free survival (PFS) was 3.1?months, and median overall survival (OS) was 11.2?months. Mutations in the epidermal growth factor receptor (EGFR) gene were analyzed in 27 patients. The response rate was higher in patients with mutant EGFR (50.0%) than in those with wild-type EGFR (11.8%, P?=?0.0288). Median PFS was 4.8 and 2.5?months (P?=?0.038), and median OS was 22.4 and 8.4?months (P?=?0.071). There was no grade 4 toxicity in this study. Five patients had grade 3 non-hematologic toxicity, and there was a trend toward higher plasma concentrations of 5-FU in those patients than in another patients.

Conclusions

S-1 monotherapy is effective and well-tolerated treatment for previously treated advanced NSCLC.     

Doxorubicin-induced suppression of poly(ADP-ribose) polymerase-1 (PARP-1) activity and expression and its implication for PARP inhibitors in clinical trials

Purpose

Monozygotic twins provide an excellent tool to study environmental effects on human health. Poly(ADP-ribose) polymerase-1 (PARP-1) is an important enzyme primarily involved in DNA repair and genomic stability and is under clinical investigation as a target for anticancer therapy. As a part of a PARP pharmacogenetics study, elderly male monozygotic twins, one healthy and the other with a Trojani grade 3 sarcoma treated with doxorubicin (DOX: 142.5 mg/m²), were recruited for the study.

Methods

PARP activity and expression were measured in peripheral blood mononuclear cells (PBMCs) by methods validated to GCLP standard and used as a pharmacodynamic endpoint for clinical trials.

Results

The mean PARP activity for the patient before treatment was 160 pmol PAR/10⁶ cells and was similar to that of his brother (130 pmol PAR/10⁶ cells). There was approximately ninefold decrease (P = 0.001) in PARP activity in a second sample from the patient taken 21 days after the first DOX administration (17 pmol PAR/10⁶ cells) and a decrease in PARP-1 expression. Investigations into BALB/C mice revealed that DOX treatment (5 mg/kg) resulted in a significant transient decrease in PARP activity after 1 h (63% control, P ? 0.05) and 24 h (53% control, P ? 0.05) but that PARP activity was restored 1 week after DOX treatment (86% control, P = 0.24).

Conclusions

We showed here that administration of DOX can have a profound effect on the measured level of PARP activity and expression in PBMCs from patients and animals. Results obtained in clinical trials where PARP activity is used as a pharmacodynamic marker of PARP inhibition could reflect the effect of a chemotherapeutic on PBMCs rather than the effectiveness of a tested PARP inhibitor.     

PTEN inhibits BMI1 function independently of its phosphatase activity

Background

The Warburg phenotype in cancer cells has been long recognized, but there is still limited insight in the consecutive metabolic alterations that characterize its establishment. We obtained better understanding of the coupling between metabolism and malignant transformation by studying mouse embryonic fibroblast-derived cells with loss-of-senescence or H-RasV12/E1A-transformed phenotypes at different stages of oncogenic progression.

Results

Spontaneous immortalization or induction of senescence-bypass had only marginal effects on metabolic profiles and viability. In contrast, H-RasV12/E1A transformation initially caused a steep increase in oxygen consumption and superoxide production, accompanied by massive cell death. During prolonged culture in vitro, cell growth rate increased gradually, along with tumor forming potential in in vitro anchorage-independent growth assays and in vivo tumor formation assays in immuno-deficient mice. Notably, glucose-to-lactic acid flux increased with passage number, while cellular oxygen consumption decreased. This conversion in metabolic properties was associated with a change in mitochondrial NAD⁺/NADH redox, indicative of decreased mitochondrial tricarboxic acid cycle and OXPHOS activity.

Conclusion

The high rate of oxidative metabolism in newly transformed cells is in marked contrast with the high glycolytic rate in cells in the later tumor stage. In our experimental system, with cells growing under ambient oxygen conditions in nutrient-rich media, the shift towards this Warburg phenotype occurred as a step-wise adaptation process associated with augmented tumorigenic capacity and improved survival characteristics of the transformed cells. We hypothesize that early-transformed cells, which potentially serve as founders for new tumor masses may escape therapies aimed at metabolic inhibition of tumors with a fully developed Warburg phenotype.     

Efficacy of EGFR tyrosine kinase inhibitors for non-adenocarcinoma NSCLC patients with EGFR mutation

Purpose

The epidermal growth factor receptor tyrosine kinase inhibitors (EGFR TKIs) gefitinib and erlotinib have shown dramatic response rate (RR) and significant prolongation of progression-free survival (PFS) in non-small-cell lung cancer (NSCLC) patients with EGFR mutation. Since only a few patients with non-adenocarcinoma histology have been enrolled in clinical trials, the efficacy of EGFR TKIs in non-adenocarcinoma NSCLC patients with EGFR mutation has not yet been fully determined.

Methods

We retrospectively analyzed clinical outcomes, including RR, PFS, and OS, in patients who were treated with the EGFR TKIs gefitinib or erlotinib and compared the results with those of adenocarcinoma patients with EGFR mutation and non-adenocarcinoma patients with wild-type EGFR.

Results

Among 250 patients with non-adenocarcinoma of the lung who underwent EGFR mutation genotyping, 21 were found to have an EGFR mutation (8.4?%). Twelve of the 21 patients were treated with the EGFR TKIs gefitinib (n?=?6) or erlotinib (n?=?6). The most common mutation was exon 19 deletion (n?=?7). The RR and disease control rate for 12 patients receiving EGFR TKIs were 50 and 75?%, respectively. The median PFS was 3.67?months (95?% CI: 1.34?C5.99), which was significantly lower than that of 269 adenocarcinoma patients with EGFR mutation (13.53?months) but better than that of 32 non-adenocarcinoma patients with wild-type EGFR (1.83?months) who were treated with EGFR TKIs.

Conclusions

The results of this study show that the EGFR mutation rate in Korean patients with non-adenocarcinoma of the lung is relatively high and that the clinical outcomes of EGFR TKIs are modest.     

Jab1 is a target of EGFR signaling in ERα-negative breast cancer

Introduction

c-Jun activation domain-binding protein-1 (Jab1) is a multifunctional signaling protein that previously has been shown to be a master regulator of a poor prognostic gene signature in invasive breast cancer and to mediate the action of S100A7. Since epidermal growth factor receptor (EGFR), like S100A7, is often expressed in estrogen receptor-alpha-negative (ERα^-) breast cancer, we set out to investigate the role of Jab1 in mediating EGFR signaling, another facet of the ERα^- phenotype.

Methods

MDA-MB-231 and MDA-MB-468 ERα^-/EGFR⁺ cell lines were assessed for localization of Jab1 and levels of downstream genes by immunofluorescence and nuclear protein extract assay following treatment with epidermal growth factor (EGF) and extracellular signal-regulated kinase (ERK) pathway inhibitor. A cohort of 424 human breast tumors was also assessed by immunohistochemistry.

Results

EGF treatment of cell lines resulted in increased Jab1 nuclear expression. This effect was inhibited by the ERK pathway inhibitor, PD98059. EGF treatment was also associated with colocalization of pERK (phosphorylated ERK) and Jab1 as well as regulation of the Jab1 downstream target gene, p27. When Jab1 activity was knocked down, p27 levels were restored to pre-EGF treatment level. Analysis of EGFR and Jab1 expression in a cohort of invasive breast tumors by tissue microarray and immunohistochemistry confirmed a relationship between EGFR and increased nuclear Jab1 within the ERα^- subset (n = 154, P = 0.019). The same association was also confirmed for S100A7 and Jab1 (P = 0.036), and high Jab1 nuclear expression was most frequent in tumors that were positive for both EGFR and S100A7 (P = 0.004).

Conclusion

Jab1 is a target of EGFR signaling in ERα^- cell lines and breast tumors and therefore may be a common central factor and potential therapeutic target for important cell signaling pathways in ERα^- breast cancer.     

EGFR expression is linked to osteopontin and Nf-κB signaling in clear cell renal cell carcinoma

Aim and background

Epidermal growth factor receptor (EGFR) is a receptor tyrosine kinase involved in many important aspects of cell biology that are related to tumorigenesis. There are opposite evidences of the role of EGFR in renal cancer and the outcome of EGFR-targeted therapies, suggesting the complexity of EGFR signaling pathways. In vitro, osteopontin (OPN) and nuclear factor kappa B (NF-κB) are thought to be involved in specific ligand-independent EGFR activation that could have a role in resistance to EGFR mAb therapy. Aim of this study was to analyze the relationship between EGFR and OPN at the protein and mRNA level, as well as their relation to NF-κB in clear cell renal cell carcinoma (CCRCC).

Materials and methods

Expression of EGFR, OPN, and p65 NF-κB protein was analyzed using immunohistochemistry and compared mutually in 88 CCRCC samples. Expression of EGFR and OPN mRNAs was analyzed using quantitative Real-time PCR in 22 CCRCC samples and compared mutually and with NF-κB protein expression.

Results

Epidermal growth factor receptor mRNA level was higher in CCRCC samples in comparison with normal renal tissue (p = 0.012) and was associated with high OPN mRNA level, and with NF-κB activation (p < 0.001 and p = 0.045, respectively). Immunohistochemical staining showed the inverse association; high EGFR protein expression was related with low OPN and NF-κB protein expression (p < 0.001 and p = 0.047, respectively).

Conclusion

Epidermal growth factor receptor gene is upregulated in CRCC and associated with OPN gene expression and NF-kB signaling. The inverse relation between OPN and EGFR at the protein level could probably reflect dynamic changes that EGFR undergoes following activation.     

Phase I study of continuous afatinib (BIBW 2992) in patients with advanced non-small cell lung cancer after prior chemotherapy/erlotinib/gefitinib (LUX-Lung 4)

Purpose

This Phase I study determined the maximum-tolerated dose (MTD) of afatinib (Afatinib is an investigational compound and its safety and efficacy have not yet been established) (BIBW 2992; trade name not yet approved by FDA), an irreversible inhibitor of epidermal growth factor receptor (EGFR)/human epidermal growth factor receptor (HER)1 and 2, up to a dose of 50?mg/day in advanced non-small cell lung cancer (NSCLC), to establish the recommended dose for Phase II.

Methods

Patients with advanced NSCLC who had received prior platinum-doublet chemotherapy and/or erlotinib/gefitinib therapy, or who were ineligible for, or not amenable to, treatment with established therapies, received oral afatinib once daily. The MTD was determined based on dose-limiting toxicities (DLTs); other assessments included safety, pharmacokinetic profile, antitumour activity according to response evaluation criteria in solid tumours and EGFR/HER1 mutation analysis where possible.

Results

Twelve evaluable patients were treated at doses of 20–50?mg/day. One DLT was observed at 50?mg/day in Course 1 (Grade 3 mucositis). The most frequent drug-related adverse events were diarrhoea, dry skin, stomatitis, rash, paronychia and anorexia; most were Grade 1 or 2. Six out of 12 patients had tumour size reductions; durable stable disease was achieved in three patients including one with EGFR/HER1 exon 19 and T790?M mutations. Peak plasma concentrations of afatinib were reached 3–4?h after administration and declined with a half-life of 30–40?h. Afatinib 50?mg/day was well tolerated with an acceptable safety profile during Phase I.

Conclusion

Recommended dose for Phase II was defined as 50?mg/day for Japanese patients; the same as for non-Japanese patients.     

Y-box binding protein 1 enhances DNA topoisomerase 1 activity and sensitivity to camptothecin via direct interaction

Background

The Y-box binding protein 1 (YB-1) possesses pleiotropic functions through its interactions with various cellular proteins, and its high expression levels make it a potential useful prognostic biomarker for cancer cells. Eukaryotic DNA topoisomerases, such as DNA topoisomerase 1 (TOPO1) and DNA topoisomerase 2 (TOPO2), are the essential DNA metabolism regulators that usually overexpressed in cancer cells, and multiple proteins have been reported to regulate the enzyme activity and the clinical efficacy of their inhibitors. The present study unraveled the interaction of YB-1 with TOPO1, and further investigated the related function and potential mechanisms during the interaction.

Methods

The direct association of TOPO1 with specific domain of YB-1 was explored by co-immunoprecipitation and GST pull-down assays. The interaction function was further clarified by DNA relaxation assays, co-immunoprecipitation and WST-8 assays with in vitro gain- and loss- of function models.

Results

We found that YB-1 interacts directly with TOPO1 (but not with TOPO2) and promotes TOPO1 catalytic activity. Interactions between YB-1 and TOPO1 increased when cancer cells were treated with the TOPO1 inhibitor, camptothecin (CPT), but not with the TOPO2 inhibitor, adriamycin (ADM). Furthermore, we found that the interaction is prevented by pretreatment with the antioxidant agent, N-acetyl cysteine, and that YB-1 downregulation renders cells resistant to CPT.

Conclusions

Our findings suggest that nuclear YB-1 serves as an intracellular promoter of TOPO1 catalytic activity that enhances CPT sensitivity through its direct interaction with TOPO1.

     

How to do it: the difficult thyroid

Background

We examine the potential prognostic and predictive roles of EGFR variant III mutation, EGFR gene copy number (GCN), human papillomavirus (HPV) infection, c-MET and p16 ^INK4A protein expression in recurrent or metastatic squamous cell carcinoma of the head and neck (R/M SCCHN).

Methods

We analyzed the archival tumor specimens of 53 patients who were treated in 4 phase II trials for R/M SCCHN. Two trials involved the EGFR inhibitor erlotinib, and 2 trials involved non-EGFR targeted agents. EGFRvIII mutation was determined by quantitative RT-PCR, HPV DNA by Linear Array Genotyping, p16 and c-MET protein expression by immunohistochemistry, and EGFR GCN by FISH.

Results

EGFRvIII mutation, detected in 22 patients (42%), was associated with better disease control, but no difference was seen between erlotinib-treated versus non-erlotinib treated patients. EGFRvIII was not associated with TTP or OS. The presence of HPV DNA (38%), p16 immunostaining (32%), c-MET high expression (58%) and EGFR amplification (27%), were not associated with response, TTP or OS.

Conclusion

EGFRvIII mutation, present in about 40% of SCCHN, appears to be an unexpected prognostic biomarker associated with better disease control in R/M SCCHN regardless of treatment with erlotinib. Larger prospective studies are required to validate its significance.     

Metaplastic breast carcinomas exhibit EGFR, but not HER2, gene amplification and overexpression: immunohistochemical and chromogenic in situ hybridization analysis

Introduction

Metaplastic breast carcinomas constitute a heterogeneous group of neoplasms, accounting for less than 1% of all invasive mammary carcinomas. Approximately 70–80% of metaplastic breast carcinomas overexpress the epidermal growth factor receptor (EGFR). Human epidermal growth factor receptor (HER)2 and EGFR have attracted much attention in the medical literature over the past few years owing to the fact that humanized monoclonal antibodies against HER2 and therapies directed against the extracellular ligand-binding domain or the intracellular tyrosine kinase domain of EGFR have proven successful in treating certain types of human cancer. We investigated whether HER2 and EGFR overexpression was present and evaluated gene amplification in a series of metaplastic breast carcinomas.

Method

Twenty-five metaplastic breast carcinomas were immunohistochemically analyzed using a monoclonal antibody (31G7) for EGFR and two antibodies for HER2 (Herceptest and CB11) and scored using the Herceptest scoring system. Gene amplification was evaluated by chromogenic in situ hybridization using Zymed Spot-Light EGFR and HER2 amplification probe. The results were evaluated by bright field microscopy under 40× and 63× objective lenses.

Results

Nineteen (76%) metaplastic breast carcinomas exhibited EGFR ovexpression, and among these EGFR amplification (defined either by large gene clusters or >5 signals/nucleus in >50% of neoplastic cells) was detected in seven cases (37%): three carcinomas with squamous differentiation and four spindle cell carcinomas. One case exhibited HER2 overexpression of grade 2+ (>10% of cells with weak to moderate complete membrane staining), but HER2 gene amplification was not detected.

Conclusion

Metaplastic breast carcinomas frequently overexpressed EGFR, which was associated with EGFR gene amplification in one-third of cases. Our findings suggest that some patients with metaplastic breast carcinomas might benefit from novel therapies targeting EGFR. Because most metaplastic breast carcinomas overexpress EGFR without gene amplification, further studies to evaluate EGFR activating mutations are warranted.     

Gastrokine 1 inhibits gastrin-induced cell proliferation

Background

Gastrokine 1 (GKN1) acts as a gastric tumor suppressor. Here, we investigated whether GKN1 contributes to the maintenance of gastric mucosal homeostasis by regulating gastrin-induced gastric epithelial cell growth.

Methods

We assessed the effects of gastrin and GKN1 on cell proliferation in stable AGS^GKN1 and MKN1^GKN1 gastric cancer cell lines and HFE-145 nonneoplastic epithelial cells. Cell viability and proliferation were analyzed by MTT and BrdU incorporation assays, respectively. Cell cycle and expression of growth factor receptors were examined by flow cytometry and Western blot analyses.

Results

Gastrin treatment stimulated a significant time-dependent increase in cell viability and proliferation in AGS^mock and MKN1^mock, but not in HFE-145, AGS^GKN1, and MKN1^GKN1, cells, which stably expressed GKN1. Additionally, gastrin markedly increased the S-phase cell population, whereas GKN1 significantly inhibited the effect of gastrin by regulating the expression of G₁/S cell-cycle regulators. Furthermore, gastrin induced activation of the NF-kB and β-catenin signaling pathways and increased the expression of CCKBR, EGFR, and c-Met in AGS and MKN1 cells. However, GKN1 completely suppressed these effects of gastrin via downregulation of gastrin/CCKBR/growth factor receptor expression. Moreover, GKN1 reduced gastrin and CCKBR mRNA expression in AGS and MKN1 cells, and there was an inverse correlation between GKN1 and gastrin, as well as between GKN1 and CCKBR mRNA expression in noncancerous gastric mucosae.

Conclusion

These data suggest that GKN1 may contribute to the maintenance of gastric epithelial homeostasis and inhibit gastric carcinogenesis by downregulating the gastrin-CCKBR signaling pathway.

     

Estimation of age- and stage-specific Catalan breast cancer survival functions using US and Catalan survival data

Background

The insulin-like growth factor (IGF) axis is an important signaling pathway in the growth and survival of many cell and tissue types. This pathway has also been implicated in many aspects of cancer progression from tumorigenesis to metastasis. The multiple roles of IGF signaling in cancer suggest that inhibition of the pathway might yield clinically effective therapeutics.

Methods

We describe A-928605, a novel pyrazolo [3,4- d]pyrimidine small molecule inhibitor of the receptor tyrosine kinases (IGF1R and IR) responsible for IGF signal transduction. This compound was first tested for its activity and selectivity via conventional in vitro kinome profiling and cellular IGF1R autophosphorylation. Additionally, cellular selectivity and efficacy of A-928605 were analyzed in an IGF1R oncogene-addicted cell line by proliferation, signaling and microarray studies. Finally, in vivo efficacy of A-928605 was assessed in the oncogene-addicted cell line and in a neuroblastoma model as a single agent as well as in combination with clinically approved therapeutics targeting EGFR in models of pancreatic and non-small cell lung cancers.

Results

A-928605 is a selective IGF1R inhibitor that is able to abrogate activation of the pathway both in vitro and in vivo. This novel compound dosed as a single agent is able to produce significant growth inhibition of neuroblastoma xenografts in vivo. A-928605 is also able to provide additive effects when used in combination with clinically approved agents directed against EGFR in non-small cell lung and human pancreatic tumor models.

Conclusion

These results suggest that a selective IGF1R inhibitor such as A-928605 may provide a useful clinical therapeutic for IGF pathway affected tumors and warrants further investigation.     

The Tumor Suppressor Function of Human Sulfatase 1 (SULF1) in Carcinogenesis

Introduction

Human sulfatase 1 (SULF1) was recently identified and shown to desulfate cellular heparan sulfate proteoglycans (HSPGs). Since sulfated HSPGs serve as co-receptors for many growth factors and cytokines, SULF1 was predicted to modulate growth factor and cytokine signaling.

Discussion

The role of SULF1 in growth factor signaling and its effects on human tumorigenesis are under active investigation. Initial results show that SULF1 inhibits the co-receptor function of HSPGs in multiple receptor tyrosine kinase signaling pathways, particularly by the heparin binding growth factors—fibroblast growth factor 2, vascular endothelial growth factor, hepatocyte growth factor, PDGF, and heparin-binding epidermal growth factor (HB-EGF). SULF1 is downregulated in the majority of cancer cell lines examined, and forced expression of SULF1 decreases cell proliferation, migration, and invasion. SULF1 also promotes drug-induced apoptosis of cancer cells in vitro and inhibits tumorigenesis and angiogenesis in vivo.

Conclusion

Strategies targeting SULF1 or the interaction between SULF1 and the related sulfatase 2 will potentially be important in developing novel cancer therapies.