Effect Of Insulin-like Growth Factor Binding Protein 4 Research Articles

Insulin-like growth factor binding protein-4 inhibits cell growth, migration and invasion, and downregulates COX-2 expression in A549 lung cancer cells.

Insulin-like growth factor binding protein 4 (IGFBP-4) and cyclooxygenase2 (COX-2) are associated with tumor inflammatory microenvironment which is involved in the progression of tumor. However, it is unclear that the roles of IGFBP-4 in lung cancer and the effects of IGFBP-4 on COX-2 expression. In this study, we showed that IGFBP-4 could decrease COX-2 production in lung cancer A549 cells. IGFBP-4 expression was significantly lower but COX-2 expression was higher in lung cancer tissues compared to matched adjacent normal tissues. In addition, IGFBP-4 could inhibit lung cancer cell proliferation, migration and invasion, and suppress the phosphorylation of PI3 K/AKT, ERK, and CREB. These results indicate that IGFBP-4 has potent antitumor effects in non-small cell lung cancer cells.

Insulin‐Like Growth Factor Binding Protein 4 Enhances Cardiomyocytes Induction in Murine‐Induced Pluripotent Stem Cells

Insulin-like growth factor binding protein 4 (IGFBP4) has been reported to play critical role in cardiomyocytes differentiation of embryonic stem cells (ESCs). But whether it promotes cardiomyocytes induction of iPSCs is unclear. In the present study, we aim to explore the role of IGFBP4 in the cardiogenesis of mouse iPSCs. We observed that IGFBP4 treatment at late stage during differentiation process of mouse iPSCs greatly enhanced the beating frequency of embryoid bodies (EBs). The expressions of Nkx2.5 (cardiac-specific transcription factor), α-MHC, α-actinin, and Troponin I (cardiac-specific protein) were significantly enhanced by IGFBP4 treatment. Immunostaining analysis showed that α-MHC, TNNT2 and connexin 43, typical cardiac markers, were obviously expressed in isolated cardiomyocytes from iPSCs with or without IGFBP4 treatment. Further study revealed that IGFBP4 had little effect on the apoptosis of EBs, but it significantly promoted the proliferation of cardiomyocytes from iPSCs characterized by higher ratio EdU positive cells in differentiated cardiomyocytes. We next observed that IGFBP4 inhibited β-catenin expression in cytosol of EBs at late stage during differentiation of iPSCs. Knockdown of β-catenin using a siRNA technique promoted the proliferation of differentiated cardiomyocytes and enhanced cardiomyocytes induction of iPSCs, suggesting that the effect of IGFBP4 on cardiomyocytes differentiation of iPSCs has relationship with β-catenin signaling pathway. In conclusion, IGFBP4 promotes cardiogenesis of iPSCs by enhancing the proliferation of differentiated cardiomyocytes through inhibiting β-catenin signaling.

PT356 VCP746, a novel A1/A2 adenosine receptor agonist, reduces hypertrophy in cardiac myocytes and collagen synthesis in cardiac fibroblasts and renal mesangial cells

Introduction: The establishment of induced pluripotent stem cells (iPSCs) potentially provides a unique resource for generating patient specific cardiomyocytes to for cardiac repair. However, the poor efficiency and yield of cardiomyocytes currently limits the application of this technology. Insulin-like growth factor binding protein 4 (IGFBP4) has been reported to play critical role in cardiomyocytes differentiation of embryonic stem cells (ESCs). But whether it promotes iPSCs into cardiomyocytes is unclear. Objectives: In the present study, we aim to explore the role of IGFBP4 in the cardiogenesis of mouse iPSCs. Methods: For differentiation, iPSCs were trypsinized and EBs were generated by the threedimensional hanging-drop method. EBs were grown in hanging drops for three days (day 0 to day 3), each drop initially consisted of 1000 cells in 30 mL of differentiation medium (growth medium without LIF). IGFBP4 (Sino Biological Inc.) was added at day 3-8,day 3-6 and day 6-8 period under 1 mg/ mL to determine the effective time-window. Results: We observed that IGFBP4 treatment at late-stage during differentiation process of mouse iPSCs greatly enhanced the beating frequency of embryoid bodies (EBs). The expressions of Nkx2.5 (cardiac specific transcription factor), a-MHC, a-actinin and Troponin I (cardiac specific protein) were significantly enhanced by IGFBP4 treatment. Immunostaining analysis showed that a-MHC, TNNT2 and connex43, typical cardiac markers, were obviously expressed in isolated cardiomyocytes from iPSCs with or without IGFBP4 treatment. Further study revealed that IGFBP4 had little effect on the apoptosis of EBs. But it significantly promoted the proliferation of cardiomycytes from iPSCs chracterized by higher ratio BrdU positive cells in differentiated cardiomyocytes. We next observed that IGFBP4 inhibted b-catenin expression in cytosol of EBs at late-stage during differentiation of iPSCs. Knockdown of b-catenin using a siRNA technique promoted the proliferation of differentiated cardiomyocytes and enhancing cardiomyocytes induction of iPSCs, suggesting that the effect of IGFBP4 on cardiomyocyte differentiation of iPSCs has relationship with b-catenin signaling pathway. Conclusion: In conclusion, IGFBP4 promotes cardiogenesis of iPSCs by enhancing the proliferation of differentiated cardiomyocytes through b-catenin signaling. Disclosure of Interest: None Declared

PT353 Identification of miRNA networks in pathological cardiac remodelling-New therapeutic targets

Introduction: The establishment of induced pluripotent stem cells (iPSCs) potentially provides a unique resource for generating patient specific cardiomyocytes to for cardiac repair. However, the poor efficiency and yield of cardiomyocytes currently limits the application of this technology. Insulin-like growth factor binding protein 4 (IGFBP4) has been reported to play critical role in cardiomyocytes differentiation of embryonic stem cells (ESCs). But whether it promotes iPSCs into cardiomyocytes is unclear. Objectives: In the present study, we aim to explore the role of IGFBP4 in the cardiogenesis of mouse iPSCs. Methods: For differentiation, iPSCs were trypsinized and EBs were generated by the threedimensional hanging-drop method. EBs were grown in hanging drops for three days (day 0 to day 3), each drop initially consisted of 1000 cells in 30 mL of differentiation medium (growth medium without LIF). IGFBP4 (Sino Biological Inc.) was added at day 3-8,day 3-6 and day 6-8 period under 1 mg/ mL to determine the effective time-window. Results: We observed that IGFBP4 treatment at late-stage during differentiation process of mouse iPSCs greatly enhanced the beating frequency of embryoid bodies (EBs). The expressions of Nkx2.5 (cardiac specific transcription factor), a-MHC, a-actinin and Troponin I (cardiac specific protein) were significantly enhanced by IGFBP4 treatment. Immunostaining analysis showed that a-MHC, TNNT2 and connex43, typical cardiac markers, were obviously expressed in isolated cardiomyocytes from iPSCs with or without IGFBP4 treatment. Further study revealed that IGFBP4 had little effect on the apoptosis of EBs. But it significantly promoted the proliferation of cardiomycytes from iPSCs chracterized by higher ratio BrdU positive cells in differentiated cardiomyocytes. We next observed that IGFBP4 inhibted b-catenin expression in cytosol of EBs at late-stage during differentiation of iPSCs. Knockdown of b-catenin using a siRNA technique promoted the proliferation of differentiated cardiomyocytes and enhancing cardiomyocytes induction of iPSCs, suggesting that the effect of IGFBP4 on cardiomyocyte differentiation of iPSCs has relationship with b-catenin signaling pathway. Conclusion: In conclusion, IGFBP4 promotes cardiogenesis of iPSCs by enhancing the proliferation of differentiated cardiomyocytes through b-catenin signaling. Disclosure of Interest: None Declared

Biology of insulin-like growth factor binding protein-4 and its role in cancer (review)

Insulin-like growth factor binding protein-4 (IGFBP-4) is an important member of the insulin-like growth factor (IGF) system. The IGFBP-4 has three domains of which the N-terminal sequence is important for the binding of IGF. It acts as a transport protein for IGF-I and IGF-II and modulates their biological effects. There is increasing evidence that IGFBP-4 inhibits IGF-induced cellular growth both in vitro and in vivo. IGFBP-4 can also mediate its actions through a mechanism independent of IGFs. IGFBP-4 level and expression in various tissues are influenced by IGFBP protease, nutrition, several growth factors and hormones. Overexpression of IGFBP-4 in transgenic animal models causes reduced growth of organs containing smooth muscle. Most cancers express IGFBP-4 at levels which correlate with their state of differentiation. However, the effects of IGFBP-4 on tumor growth are uncertain. In vitro studies have shown that overexpression of IGFBP-4 inhibit the growth of some colon cancer cells. Overexpression of IGFBP-4 in vivo has been reported to decrease the growth of prostate cancer. The effect of altered expression of IGFBP-4 in vivo in colon and other cancers needs to be explored as locally available IGFs appear to stimulate mitogenesis.

Overexpression of insulin-like growth factor-binding protein-4 (IGFBP-4) in smooth muscle cells of transgenic mice through a smooth muscle alpha-actin-IGFBP-4 fusion gene induces smooth muscle hypoplasia.

Insulin-like growth factor I (IGF-I) has been postulated to function as a smooth muscle cell (SMC) mitogen and to play a role in the pathogenesis of bladder hypertrophy, estrogen-induced uterine growth, and restenosis after arterial angioplasty. IGF-binding protein-4 (IGFBP-4) inhibits IGF-I action in vitro and is the most abundant IGFBP in the rodent arterial wall. To explore the function of this binding protein in vivo, transgenic mouse lines were developed harboring fusion genes consisting of a rat IGFBP-4 complementary DNA cloned downstream of either a -724 bp fragment of the mouse smooth muscle alpha-actin 5'-flanking region (SMP2-BP-4) or -1074 bp, 63 bp of 5'-untranslated region, and 2.5 kb of intron 1 of smooth muscle alpha-actin (SMP8-BP-4). SMP2-BP-4 mice expressed low levels of the exogenous IGFBP-4 messenger RNA (mRNA), which was not specifically targeted to SMC-rich tissue environments, and were therefore not analyzed further. Six SMP8-BP-4 transgenic lines derived from separate founders were characterized. Mating of hemizygous SMP8-BP-4 mice with controls produced about 50% transgenic offspring, with equal sex distribution. Expression of IGFBP-4 mRNA in nontransgenic littermates was maximal in liver and kidney. By contrast, transgenic IGFBP-4 mRNA expression, distinguished because of a smaller transcript size, was confined to SMC-containing tissues, with the following hierarchy: bladder > aorta > stomach = uterus. There was no transgene expression in skeletal muscle, brain, or cardiac myocytes. The abundance of IGFBP-4 measured by Western ligand blotting or by immunoblotting, was 8- to 10-fold higher in aorta and bladder of SMP8-BP-4 mice than in their nontransgenic littermates, with no change in plasma IGFBP-4 levels. Transgenic mice exhibited a significant reduction in wet weight of SMC-rich tissues, including bladder, intestine, aorta, uterus, and stomach, with no change in total body or carcass weight. In situ hybridization showed that transgene expression was targeted exclusively to the muscular layers of the arteries, veins, bladder, ureter, stomach, intestine, and uterus. Overexpression of IGFBP-4 was associated with SMC hypoplasia, a reciprocal phenotype to that of transgenic mice overexpressing IGF-I under control of the same promoter (SMP8-IGF-I). Double transgenic mice derived from mating SMP8-BP-4 with SMP8-IGF-I animals showed a modest decrease in wet weight at selected SMC tissues. Although we cannot exclude that the effects of IGFBP-4 may be IGF independent, these data suggest that IGFBP-4 is a functional antagonist of IGF-I action on SMC in vivo.