Insulin growth factor binding protein 2 mediates the progression of lymphangioleiomyomatosis

Evidence for shared genetic risk factors between lymphangioleiomyomatosis and pulmonary function

Introduction

Lymphangioleiomyomatosis (LAM) is a rare low-grade metastasising disease characterised by cystic lung destruction. The genetic basis of LAM remains incompletely determined, and the disease cell-of-origin is uncertain. We analysed the possibility of a shared genetic basis between LAM and cancer, and LAM and pulmonary function.

Methods

The results of genome-wide association studies of LAM, 17 cancer types and spirometry measures (forced expiratory volume in 1 s (FEV1), forced vital capacity (FVC), FEV1/FVC ratio and peak expiratory flow (PEF)) were analysed for genetic correlations, shared genetic variants and causality. Genomic and transcriptomic data were examined, and immunodetection assays were performed to evaluate pleiotropic genes.

Results

There were no significant overall genetic correlations between LAM and cancer, but LAM correlated negatively with FVC and PEF, and a trend in the same direction was observed for FEV1. 22 shared genetic variants were uncovered between LAM and pulmonary function, while seven shared variants were identified between LAM and cancer. The LAM-pulmonary function shared genetics identified four pleiotropic genes previously recognised in LAM single-cell transcriptomes: ADAM12, BNC2, NR2F2 and SP5. We had previously associated NR2F2 variants with LAM, and we identified its functional partner NR3C1 as another pleotropic factor. NR3C1 expression was confirmed in LAM lung lesions. Another candidate pleiotropic factor, CNTN2, was found more abundant in plasma of LAM patients than that of healthy women.

Conclusions

This study suggests the existence of a common genetic aetiology between LAM and pulmonary function.

Oestrogen actions contribute to female gender-specific risks in the development of lung carcinoma

Lung cancer is increasing in incidence particularly among women, associated with a global change in smoking habits. Steroid hormones, particularly oestrogen exert an influence on tumour progression in tissues where their target receptor is expressed. Oestrogen receptor, particularly ERβ is highly expressed in the lung and becomes more highly expressed in lung carcinogenesis. Genes involved in the process of lung carcinoma progression and signalling cascades linked to invasion and angiogenesis are modulated by oestrogen receptors. This review intends to collate recently published evidence identifying a role for oestrogen in the initiation and progression of lung carcinoma and how these two processes are differentially affected by circulating oestrogens both in women and in men. Circulating oestrogens may be a significant risk factor in women's susceptibility to lung carcinoma and also provide an additional approach for more targeted therapy.

Expression of genes encoding IGF1, IGF2, and IGFBPs in blood of obese adolescents with insulin resistance

OBJECTIVE

The development of obesity and its metabolic complications is associated with dys-regulation of various intrinsic mechanisms, which control basic metabolic processes via changes in the expression of numerous regulatory genes. The main goal of this work was to study the association between the expression of insulin-like growth factors (IGF1 and IGF2) and IGF-binding proteins and insulin resistance in obese adolescents for evaluation of possible contribution of these genes in development of insulin resistance.

METHODS

The expression of IGF1, IGF2, and IGFBPs mRNA was measured in blood of obese adolescents with normal insulin sensitivity and insulin resistance in comparison with the normal (control) individuals.

RESULTS

In the blood of obese adolescents with normal insulin sensitivity the expression of IGFBP4, IGFBP5 and HTRA1 genes was down-regulated, but IGFBP2 and IGFBP7 genes up-regulated as compared to control (normal) group. At the same time, no significant changes in IGF1 and IGF2 gene expressions in this group of obese adolescents were found. Insulin resistance in obese adolescents led to up-regulation of IGF2, IGFBP2, and IGFBP7 gene expressions as well as to down-regulation of the expression of IGF1, IGFBP5 and HTRA1 genes in the blood in comparison with the obese patients, which have normal insulin sensitivity. Furthermore, the level of IGFBP4 gene expression was similar in both groups of obese adolescents.

CONCLUSIONS

Results of this investigation provide evidence that insulin resistance in obese adolescents is associated with gene specific changes in the expression of IGF1, IGF2, IGFBP2, IGFBP5, IGFBP7, and HTRA1 genes and these changes possibly contribute to the development of glucose intolerance and insulin resistance.

Activation of EGFR-DNA-PKcs pathway by IGFBP2 protects esophageal adenocarcinoma cells from acidic bile salts-induced DNA damage

Background

The incidence of esophageal adenocarcinoma (EAC) is rising rapidly in the US and Western countries. The development of Barrett’s esophagus (BE) and its progression to EAC have been linked to chronic gastroesophageal reflux disease (GERD). Exposure of BE and EAC cells to acidic bile salts (ABS) in GERD conditions induces high levels of oxidative stress and DNA damage. In this study, we investigated the role of insulin-like growth factor binding protein 2 (IGFBP2) in regulating ABS-induced DNA double-strand breaks.

Methods

Real-time RT-PCR, western blot, immunohistochemistry, immunofluorescence, co-immunoprecipitation, flow cytometry, and cycloheximide (CHX) chase assays were used in this study. To mimic GERD conditions, a cocktail of acidic bile salts (pH 4) was used in 2D and 3D organotypic culture models. Overexpression and knockdown of IGFBP2 in EAC cells were established to examine the functional and mechanistic roles of IGFBP2 in ABS-induced DNA damage.

Results

Our results demonstrated high levels of IGFBP2 mRNA and protein in EAC cell lines as compared to precancerous Barrett’s cell lines, and IGFBP2 is frequently overexpressed in EACs (31/57). Treatment of EAC cells with ABS, to mimic GERD conditions, induced high levels of IGFBP2 expression. Knocking down endogenous IGFBP2 in FLO1 cells (with constitutive high levels of IGFBP2) led to a significant increase in DNA double-strand breaks and apoptosis, following transient exposure to ABS. On the other hand, overexpression of exogenous IGFBP2 in OE33 cells (with low endogenous levels of IGFBP2) had a protective effect against ABS-induced double-strand breaks and apoptosis. We found that IGFBP2 is required for ABS-induced nuclear accumulation and phosphorylation of EGFR and DNA-PKcs, which are necessary for DNA damage repair activity. Using co-immunoprecipitation assay, we detected co-localization of IGFBP2 with EGFR and DNA-PKcs, following acidic bile salts treatment. We further demonstrated, using cycloheximide chase assay, that IGFBP2 promotes EGFR protein stability in response to ABS exposure.

Conclusions

IGFBP2 protects EAC cells against ABS-induced DNA damage and apoptosis through stabilization and activation of EGFR - DNA-PKcs signaling axis.

Electronic supplementary material

The online version of this article (10.1186/s13046-018-1021-y) contains supplementary material, which is available to authorized users.

Lymphangioleiomyomatosis: a case report and review of diagnosis and treatment

Lymphangioleiomyomatosis (LAM) is a rare disease that generally affects young women and involves the abnormal proliferation of smooth muscle-like cells (LAM cells) in the lungs (pulmonary LAM) and extrapulmonary sites (extrapulmonary LAM). This disease is rare in males. It is hard to distinguish between lung cancer and pulmonary LAM, especially during early stages. Herein, we present a case of a 66-year-old man with a small nodule in the right upper lobe that was first diagnosed as a lung malignancy using a chest CT scan. After a wedge dissection, a pathologist performed a histologic and immunohistochemical examination, and a diagnosis of pulmonary LAM was made. We further performed a 518-gene panel analysis using next-generation sequencing, and only three genes, BARD1, BLM, and BRCA2, were found to have mutations. We also provide a summary of the diagnosis and treatment of this disease.

IGFBP2 promotes salivary adenoid cystic carcinoma metastasis by activating the NF-κB/ZEB1 signaling pathway

Metastasis is a major cause of poor prognosis in patients suffered with salivary adenoid cystic carcinoma (SACC), in which many factors are implicated. In this study, we identified that IGFBP2, overexpressed in SACC, correlated positively with perineural invasion or metastasis and indicated worse outcome. Moreover, IGFBP2 overexpression could dramatically improve motility and invasion capacity of SACC cells in vitro. Mechanically, IGFBP2 enhanced expression of ZEB1 in a NF-κB (p65)-dependent manner and then promoted epithelial-mesenchymal transition (EMT) in SACC. In addition, IGFBP2 mutation in the nuclear localization signal could impede nuclear translocation of p65, lower ZEB1 expression, and abrogate the EMT process. In xenograft models, IGFBP2 overexpression promoted lung and liver metastases of SACC cells; while if nuclear IGFBP2 was reduced, the formation of metastases in lung and liver was weakened. Together, these results for the first time demonstrate that IGFBP2 plays an important role in invasion and metastasis of SACC through the NF-κB/ZEB1 signaling pathway and IGFBP2 may be a novel biomarker and target for SACC.

Rapamycin-independent IGF2 expression in Tsc2-null mouse embryo fibroblasts and human lymphangioleiomyomatosis cells

Lymphangioleiomyomatosis (LAM) is a rare, almost exclusively female lung disease linked to inactivating mutations in tuberous sclerosis complex 2 (TSC2), a tumor suppressor gene that controls cell metabolic state and growth via regulation of the mechanistic target of rapamycin (mTORC1) signaling. mTORC1 is frequently activated in human cancers and, although the mTORC1 inhibitor rapamycin has a cytostatic effect, it is, in general, unable to elicit a robust curative effect or tumor regression. Using RNA-Seq, we identified (1) Insulin-like Growth Factor (IGF2) as one of the genes with the highest fold-change difference between human TSC2-null and TSC2-expressing angiomyolipoma cells from a patient with LAM, and (2) the mouse IGF2 homolog Igf2, as a top-ranking gene according to fold change between Tsc2^-/- and Tsc2^+/+ mouse embryo fibroblasts (MEFs). We extended transcript-level findings to protein level, observing increased Igf2 protein expression and Igf2 secretion by Tsc2^-/- MEFs. Increased Igf2 expression was not due to epigenetic imprinting, but was partially mediated through the Stat3 pathway and was completely insensitive to rapamycin treatment. An siRNA-mediated decrease of Igf2 resulted in decreased Stat3 phosphorylation, suggesting presence of an autocrine Igf2/Stat3 amplification cycle in Tsc2^-/- MEFs. In human pulmonary LAM lesions and metastatic cell clusters, high levels of IGF2 were associated with mTORC1 activation. In addition, treatment of three primary IGF2-expressing LAM lung cell lines with rapamycin did not result in IGF2 level changes. Thus, targeting of IGF2 signaling may be of therapeutic value to LAM patients, particularly those who are unresponsive to rapamycin.