Inhibition of VEGF secretion and experimental choroidal neovascularization by picropodophyllin (PPP), an inhibitor of the insulin-like growth factor-1 receptor

Mutant PP2A Induces IGFBP2 Secretion to Promote Development of High-Grade Uterine Cancer

Uterine serous carcinoma (USC) and uterine carcinosarcoma (UCS) tumors are uniquely aggressive, suggesting that the primary tumor is intrinsically equipped to disseminate and metastasize. Previous work identified mutational hotspots within PPP2R1A, which encodes the Aα scaffolding subunit of protein phosphatase 2A (PP2A), a heterotrimeric serine/threonine phosphatase. Two recurrent heterozygous PPP2R1A mutations, P179R and S256F, occur exclusively within high-grade subtypes of uterine cancer and can drive tumorigenesis and metastasis. Elucidation of the mechanisms by which PP2A Aα mutants promote tumor development and progression could help identify therapeutic opportunities. Here, we showed that expression of these mutants in USC/UCS cell lines enhanced tumor-initiating capacity, drove a hybrid epithelial-to-mesenchymal plasticity phenotype, and elevated secretion of the tumorigenic cytokine insulin growth factor (IGF) binding protein 2 (IGFBP2). Therapeutic targeting of the IGFBP2/IGF receptor 1 signaling axis using small molecules and genetic approaches resulted in marked tumor growth inhibition. Mechanistically, PP2A regulated IGFBP2 expression through the transcription factor, NF-κB, which harbors a B56 recognition motif. Collectively, these results identify a role for PP2A in regulating paracrine cancer cell signaling that can be targeted to block the initiation and metastasis of high-grade uterine cancer. Significance: Elevated IGFBP2 secretion by uterine cancer cells with heterozygous PPP2R1A mutations supports tumor progression and confers a vulnerability to IGFBP2/IGF1R inhibition as a therapeutic approach for this highly aggressive cancer subtype.

IGF-1 Promotes Epithelial-Mesenchymal Transition of Lens Epithelial Cells That Is Conferred by miR-3666 Loss

The abnormal proliferation, migration, and epithelial-mesenchymal transformation (EMT) of lens epithelial cells (LECs) are the main reasons for vision loss caused by posterior capsular opacification (PCO) after cataract surgery. Insulin-like growth factor-1 (IGF-1) was found to be associated with the pathogenesis of cataracts, but its biological role in PCO is poorly understood. In the present study, IGF-1 overexpression facilitated the proliferation, migration, and EMT, whereas knockdown of IGF-1 markedly suppressed the proliferation, migration, and TGF-β2-induced EMT of LECs. Additionally, to evaluate valuable microRNAs (miRNAs) which target IGF-1 to modulate LEC-EMT, we predicted miR-3666 might regulate IGF-1 by binding its 3'UTR according to the bioinformatics database. Furthermore, we verified that miR-3666 directly targeted IGF-1 by luciferase reporter assay. By using miR-3666 mimics, cell proliferation, migration, and invasion were suppressed, while being enhanced by the reduction of miR-3666. Knockout of IGF1 reverses the effect of the miR-3666 inhibitor on the malignant behavior of LECs. These results indicate the role of miR-3666/IGF-1 in LEC-EMT that offers new strategies for the therapy and prevention of PCO.

Scutellarin Prevents Angiogenesis in Diabetic Retinopathy by Downregulating VEGF/ERK/FAK/Src Pathway Signaling

BACKGROUND

Diabetic retinopathy (DR) is a serious microvascular complication of diabetes. This study demonstrates the antiangiogenic effects of scutellarin (SCU) on high glucose- and hypoxia-stimulated human retinal endothelial cells (HRECs) and on a diabetic rat model by oral administration. The antiangiogenic mechanisms of SCU in vitro and in vivo were investigated.

METHOD

HRECs were cultured in high glucose- (30 mM D-glucose) and hypoxia (cobalt chloride-treated)-stimulated diabetic condition to evaluate the antiangiogenic effects of SCU by CCK-8 test, cell migration experiment (wound healing and transwell), and tube formation experiment. A streptozotocin-induced type II diabetic rat model was established to measure the effects of oral administration of SCU on protecting retinal microvascular dysfunction by Doppler waveforms and HE staining. We further used western blot, luciferase reporter assay, and immunofluorescence staining to study the antiangiogenic mechanism of SCU. The protein levels of phospho-ERK, phospho-FAK, phospho-Src, VEGF, and PEDF were examined in HRECs and retina of diabetic rats.

RESULT

Our results indicated that SCU attenuated diabetes-induced HREC proliferation, migration, and tube formation and decreased neovascularization and resistive index in the retina of diabetic rats by oral administration. SCU suppressed the crosstalk of phospho-ERK, phospho-FAK, phospho-Src, and VEGF in vivo and in vitro.

CONCLUSIONS

These results suggested that SCU can be an oral drug to alleviate microvascular dysfunction of DR and exerts its antiangiogenic effects by inhibiting the expression of the crosstalk of VEGF, p-ERK, p-FAK, and p-Src.

Circulating insulin-like growth factor-1: a new clue in the pathogenesis of age-related macular degeneration

In order to investigate Insulin-like growth factor-1 (IGF-1) blood levels in male and female age-matched patients affected by early, intermediate, neovascular age related macular degeneration (AMD) and healthy subjects (no AMD) were enrolled in a prospective, observational study. All patients enrolled were classified according to 4 stages classification of AMD from Age-related eye disease study (AREDS). Each subject underwent a complete ophthalmic examination including best corrected visual acuity (BCVA), applanation tonometry, slit-lamp biomicroscopic examination, color fundus photography, optical coherence tomography (OCT) and, if needed, fluorescein angiography. Overall, 224 anti-VEGF naïve subjects including 56 patients in early AMD group, 56 patients in intermediate AMD group, 56 patients in neovascular AMD group and 56 patients in no AMD group were recruited. For each group 28 male patients and 28 female patients were enrolled. IGF-1 hematic levels were significantly higher (p<0.005) in the neovascular AMD group and in the intermediate AMD group in comparison to no AMD group; no significant difference between early AMD group and no AMD group was found. Our analysis has shown an increment of IGF-1 levels in both neovascular and intermediate stage of AMD supporting the hypothesis that IGF-1 may play a role in the pathogenesis of AMD.

Circulating insulin-like growth factor-1: a new clue in the pathogenesis of age-related macular degeneration

In order to investigate Insulin-like growth factor-1 (IGF-1) blood levels in male and female age-matched patients affected by early, intermediate, neovascular age related macular degeneration (AMD) and healthy subjects (no AMD) were enrolled in a prospective, observational study. All patients enrolled were classified according to 4 stages classification of AMD from Age-related eye disease study (AREDS). Each subject underwent a complete ophthalmic examination including best corrected visual acuity (BCVA), applanation tonometry, slit-lamp biomicroscopic examination, color fundus photography, optical coherence tomography (OCT) and, if needed, fluorescein angiography. Overall, 224 anti-VEGF naïve subjects including 56 patients in early AMD group, 56 patients in intermediate AMD group, 56 patients in neovascular AMD group and 56 patients in no AMD group were recruited. For each group 28 male patients and 28 female patients were enrolled. IGF-1 hematic levels were significantly higher (p<0.005) in the neovascular AMD group and in the intermediate AMD group in comparison to no AMD group; no significant difference between early AMD group and no AMD group was found. Our analysis has shown an increment of IGF-1 levels in both neovascular and intermediate stage of AMD supporting the hypothesis that IGF-1 may play a role in the pathogenesis of AMD.

Systemic endothelial function in cases with wet-type age-related macular degeneration

BACKGROUND

Choroidal endothelial dysfunction plays key role in wet-type age-related macular degeneration (AMD). Peripheral vascular endothelial function is not known in wet AMD.

OBJECTIVE

We aimed to analyze peripheral vascular endothelial function in cases with wet-type age-related macular degeneration by measuring flow-mediated dilatation (FMD).

MATERIALS AND METHODS

The study included 20 cases with wet AMD (Group 1, mean age 65.9 ± 7.2 years) and 24 healthy individuals (Group 2, mean age 62.0 ± 11.9 years). In all cases, a cardiologist assessed the responses of endothelial function by measuring the FMD following brachial artery occlusion.

RESULTS

Mean FMD, an indicator of endothelial function was found to be 6.4 ± 2.7 % in Group 1 and 15.6 ± 7.3 % in Group 2 (p < 0.001). There was no significant difference between patient and control groups regarding age, sex, total cholesterol, LDL cholesterol, HDL cholesterol, triglyceride, ESR and CRP.

CONCLUSION

Reduced FMD is present in patients with wet AMD, suggesting that impaired peripheral endothelial function may be involved in its pathogenesis.

Effects of epidermal growth factor receptor and insulin-like growth factor 1 receptor inhibition on proliferation and intracellular signaling in cutaneous SCCHN: potential for dual inhibition as a therapeutic modality

BACKGROUND

Combined inhibition of epidermal growth factor receptor (EGFR) and insulin-like growth factor-1 receptor (IGF-1R) has been proposed as a therapy for cutaneous squamous cell carcinoma of the head and neck (SCCHN).

METHODS

Receptor expression and downstream signaling were assessed in cutaneous squamous cell carcinoma (SCC) cell lines and patient samples. EGFR and IGF-1R signaling was inhibited in cutaneous SCC cell lines using erlotinib and/or picropodophyllin.

RESULTS

EGFR and IGF-1R were overexpressed in cutaneous SCCHN specimens relative to normal skin. Dual inhibition of both receptors prevented cell growth and decreased activation of Akt and p42/44 mitogen-activated protein kinase (MAPK) more effectively than either inhibitor alone.

CONCLUSION

Dual inhibition of EGFR and IGF-1R is effective at blocking cell growth, and is correlated with inhibition of Akt and p42/44 MAPK, suggesting that this may be a promising treatment for cutaneous SCCHN.

Animals as models of age-related macular degeneration: an imperfect measure of the truth

Age-related macular degeneration (AMD) is a degenerative condition that begins in Bruch's membrane and progresses to involve the retinal pigment epithelium and ultimately the overlying photoreceptors. The only required etiologic factor is age, and AMD is regarded as the leading cause of blindness in individuals older than 65 years. AMD results from variable contributions of age, environment, and genetic predisposition. Many loci are linked to AMD; in the majority of cases, the disease is associated with polymorphisms within these genes, rather than mutations that ablate gene function. The etiologic complexity of AMD is reflected by the paucity of animal models that entirely replicate the human disease. This review compares the salient anatomy of the primate and rodent retina, particularly in the light of AMD pathology. It next discusses prevailing hypotheses explaining how AMD may develop. These include the role of complement activation and macrophage chemotaxis in AMD, molecular mechanisms of choroidal neovascularization, and the roles of oxidative damage and lipid metabolism. Finally, the article gives an overview of spontaneous and induced nonhuman primate models and describes relevant mouse models in the context of each pathogenetic mechanism.