Emerging role of insulin-like growth factor-binding protein 7 in hepatocellular carcinoma

Insulin-like growth factor-binding protein 7 (IGFBP7): A microenvironment-dependent regulator of angiogenesis and vascular remodeling

Insulin-like Growth Factor-Binding Protein 7 (IGFBP7) is an extracellular matrix (ECM) glycoprotein, highly enriched in activated vasculature during development, physiological and pathological tissue remodeling. Despite decades of research, its role in tissue (re-)vascularization is highly ambiguous, exhibiting pro- and anti-angiogenic properties in different tissue remodeling states. IGFBP7 has multiple binding partners, including structural ECM components, cytokines, chemokines, as well as several receptors. Based on current evidence, it is suggested that IGFBP7's bioactivity is strongly dependent on the microenvironment it is embedded in. Current studies indicate that during physiological angiogenesis, IGFBP7 promotes endothelial cell attachment, luminogenesis, vessel stabilization and maturation. Its effects on other stages of angiogenesis and vessel function remain to be determined. IGFBP7 also modulates the pro-angiogenic properties of other signaling factors, such as VEGF-A and IGF, and potentially acts as a growth factor reservoir, while its actual effects on the factors' signaling may depend on the environment IGFBP7 is embedded in. Besides (re-)vascularization, IGFBP7 clearly promotes progenitor and stem cell commitment and may exhibit anti-inflammatory and anti-fibrotic properties. Nonetheless, its role in inflammation, immunomodulation, fibrosis and cellular senescence is again likely to be context-dependent. Future studies are required to shed more light on the intricate functioning of IGFBP7.

The Rise of IGFBP4 in People with Obstructive Sleep Apnea and Multilevel Sleep Surgery Recovers Its Basal Levels

IGFBP4 is the smallest member of the insulin-like growth factor binding protein family (IGFBP). It is a hepatic protein that plays a role in modulating the activity and bioavailability of IGF-I. The expression of IGFBP4 was found to increase under conditions of hypoxia. Obstructive sleep apnea (OSA) is a common disorder, characterized by cyclic episodes of intermittent hypoxia and fragmented sleep. Our aim was to quantify levels of circulating IGFBP1, IGFBP2, IGFBP3, IGFBP4, and IGFBP7 in fasting plasma samples of 69 Kuwaiti participants and explore its correlation with indices of OSA. The quantification was performed using multiplexing assay. The study involved 28 controls and 41 patients with OSA. Levels of circulating IGFBP4 were significantly higher in people with OSA (289.74 ± 23.30 ng/ml) compared to the control group (217.60 ± 21.74 ng/ml, p = 0.028). The increase in IGFBP4 correlated significantly and positively with AHI (r = .574, p = .01) and AI (r = .794, p = .001) in people with moderate and severe OSA. There was a significant decline in circulating IGFBP4 after 3 months of surgery (225.89 ± 18.16 ng/ml, p = 0.012). This was accompanied by a prominent improvement in OSA (AHI 8.97 ± 2.37 events/h, p = 0.001). In this study, our data showed a significant increase in circulating IGFBP4 in people with OSA. We also report a significant positive correlation between IGFBP4 and indices of OSA at baseline, which suggests IGFBP4 as a potential diagnostic biomarker for OSA. There was a significant improvement in OSA after 3 months of surgical intervention, which concurred with a significant decline in IGFBP4 levels. Altogether, the detected change suggests a potential link between IGFBP4 and OSA or an OSA-related factor, whereby OSA might play a role in triggering the induction of IGFBP4 expression.

Epithelial cell senescence: an adaptive response to pre-carcinogenic stresses?

Senescence is a cell state occurring in vitro and in vivo after successive replication cycles and/or upon exposition to various stressors. It is characterized by a strong cell cycle arrest associated with several molecular, metabolic and morphologic changes. The accumulation of senescent cells in tissues and organs with time plays a role in organismal aging and in several age-associated disorders and pathologies. Moreover, several therapeutic interventions are able to prematurely induce senescence. It is, therefore, tremendously important to characterize in-depth, the mechanisms by which senescence is induced, as well as the precise properties of senescent cells. For historical reasons, senescence is often studied with fibroblast models. Other cell types, however, much more relevant regarding the structure and function of vital organs and/or regarding pathologies, are regrettably often neglected. In this article, we will clarify what is known on senescence of epithelial cells and highlight what distinguishes it from, and what makes it like, replicative senescence of fibroblasts taken as a standard.

[Effects of maternal folate deficiency on the methylation of insulin-like growth factor system in the offspring rats]

OBJECTIVE

To study the effects of maternal folate deficiency on fetal growth and development and the methylation profiles of insulin-like growth factor system in the offspring rats.

METHODS

Twenty-two Sprague-Dawley female rats were randomly assigned to two groups: a folate deficient group (n=12) and a control group (n=10). They were fed with folate deficient and normal diet respectively. Dams were mated after 2 weeks of feeding. Eight female rats from each group were pregnant. On the 20th day of gestation, the fetuses were delivered by caesarean section. Thirty-two fetal rats from each group were randomly selected and the body length and weight were measured. Eight fetal rats from each group were randomly selected and ELISA was used to measure the level of folate content, IGF-1 and IGFBP-3 in the fetal brain and liver. Three fetal rats from each group were randomly selected and methylated DNA immunoprecipitation sequencing (MeDIP-Seq) was used to detect the methylation level of insulin-like growth factor system in the fetal brain and liver. ELISA was used to measure the level of IGF-1 and IGFBP-3 in the maternal serum from both groups.

RESULTS

The mean fetal length and weight were lower in the folate deficient group than in the control group (P<0.05). The levels of IGF-1 and IGFBP-3 in the maternal serum, as well as folate content and IGFBP-3 in the fetal brain and liver were significantly lower in the folate deficient group than in the control group (P<0.05). The methylation levels of IGF-1R, IGF-2R, IGFBP-2, IGFBP-5, IGFBP-6 and IGFBP-7 in the fetal brain were higher in the folate deficient group than in the control group (P<0.05). The methylation levels of IGF-1R, IGF-2R, IGFBP-3 and IGFBP-5 in the fetal liver were higher in the folate deficient group than in the control group. The methylation of IGF-2 gene showed a significant reduction in the folate deficient group (P<0.05).

CONCLUSIONS

Maternal folate deficiency may cause retardation of growth and development of the offspring, which is possibly associated with the changes of methylation profiles of insulin-like growth factors.