Gestational diabetes and maternal obesity are associated with sex-specific changes in miRNA and target gene expression in the fetus.

BACKGROUND/OBJECTIVES: Pregnancies complicated by gestational diabetes (GDM) or maternal obesity have been linked to the development of diabetes, obesity, and fatty liver disease later in life with sex-specific manifestations. Alterations in miRNA expression in offspring exposed to GDM and maternal obesity and effects on hepatic development are unknown. Here, we describe how exposure to maternal obesity in utero leads to sex-specific changes in miRNA and target gene expression in human fetal liver. METHODS: Candidate miRNA expression was measured in second trimester amniotic fluid (AF) from women with GDM. Targets of differentially expressed miRNAs were determined and pathway enrichment of target genes was performed. MiRNA and target gene expression were measured in a separate cohort of second trimester primary human fetal hepatocytes (PHFH) exposed to maternal obesity via qPCR and western blot. All studies were IRB approved. RESULTS: GDM-exposed AF had significant increases in miRNAs 199a-3p, 503-5p, and 1268a (fold change (FC) ≥ 1.5, p < 0.05). Female offspring-specific analysis showed enrichment in miRNAs 378a-3p, 885-5p, and 7-1-3p (p < 0.05). MiRNA gene targets were enriched in hepatic pathways. Key genes regulating de novo lipogenesis were upregulated in obesity-exposed PHFH, especially in males. Significantly altered miRNAs in GDM AF were measured in obese-exposed PHFH, with consistent increases in miRNAs 885-5p, 199-3p, 503-5p, 1268a, and 7-1-3p (FC ≥ 1.5, p < 0.05). Female PHFH exposed to maternal obesity had increased expression of miR-885-5p, miR-199-3p, miR-503-5p, miR-1268s, and miR-7-1-3p (p < 0.05), corresponding to decreased target genes expression for ABCA1, PAK4, and INSR. In male PHFHs, no miRNA changes were measured but there was increased expression of ABCA1, PAK4, and INSR (p < 0.05). CONCLUSIONS: Our data suggest sex-specific changes in miRNA and gene expression in PHFH may be one mechanism contributing to the sexual dimorphism of metabolic disease in offspring exposed to GDM and maternal obesity in utero.

Gestational Diabetes Alters the Metabolomic Profile in 2nd Trimester Amniotic Fluid in a Sex-Specific Manner.

Maternal diabetes and obesity induce marked abnormalities in glucose homeostasis and insulin secretion in the fetus, and are linked to obesity, diabetes, and metabolic disease in the offspring, with specific metabolic characterization based on offspring sex. Gestational diabetes (GDM) has profound effects on the intrauterine milieu, which may reflect and/or modulate the function of the maternal⁻fetal unit. In order to characterize metabolic factors that affect offspring development, we profiled the metabolome of second trimester amniotic fluid (AF) from women who were subsequently diagnosed with gestational diabetes (GDM) using a targeted metabolomics approach, profiling 459 known biochemicals through gas chromatography/mass spectrometry (GC/MS) and liquid chromatography/mass spectrometry (LC/MS) assays. Using a nested case-control study design, we identified 69 total biochemicals altered by GDM exposure, while sex-specific analysis identified 44 and 58 metabolites in male and female offspring, respectively. The most significant changes were in glucose, amino acid, glutathione, fatty acid, sphingolipid, and bile acid metabolism with specific changes identified based on the offspring sex. Targeted isotope dilution LC/MS confirmatory assays measured significant changes in docosahexaenoic acid and arachidonic acid. We conclude that the sex-specific alterations in GDM maternal⁻fetal metabolism may begin to explain the sex-specific metabolic outcomes seen in offspring exposed to GDM in utero.

BRAF Inhibition Stimulates Melanoma-Associated Macrophages to Drive Tumor Growth.

PURPOSE: To investigate the roles of melanoma-associated macrophages in melanoma resistance to BRAF inhibitors (BRAFi). EXPERIMENTAL DESIGN: An in vitro macrophage and melanoma cell coculture system was used to investigate whether macrophages play a role in melanoma resistance to BRAFi. The effects of macrophages in tumor resistance were examined by proliferation assay, cell death assay, and Western blot analyses. Furthermore, two mouse preclinical models were used to validate whether targeting macrophages can increase the antitumor activity of BRAFi. Finally, the number of macrophages in melanoma tissues was examined by immunohistochemistry. RESULTS: We demonstrate that in BRAF-mutant melanomas, BRAFi paradoxically activate the mitogen-activated protein kinase (MAPK) pathway in macrophages to produce VEGF, which reactivates the MAPK pathway and stimulates cell growth in melanoma cells. Blocking the MAPK pathway or VEGF signaling then reverses macrophage-mediated resistance. Targeting macrophages increases the antitumor activity of BRAFi in mouse and human tumor models. The presence of macrophages in melanomas predicts early relapse after therapy. CONCLUSIONS: Our findings demonstrate that macrophages play a critical role in melanoma resistance to BRAFi, suggesting that targeting macrophages will benefit patients with BRAF-mutant melanoma.

Melanoma-derived conditioned media efficiently induce the differentiation of monocytes to macrophages that display a highly invasive gene signature.

The presence of tumor-associated macrophages (TAMs) in melanomas is correlated with a poor clinical prognosis. However, there is limited information on the characteristics and biological activities of human TAMs in melanomas. In this study, we developed an in vitro method to differentiate human monocytes to macrophages using modified melanoma-conditioned medium (MCM). We demonstrate that factors from MCM-induced macrophages (MCMI-Mφ) express both M1-Mφ and M2-Mφ markers and inhibit melanoma-specific T-cell proliferation. Furthermore, microarray analyses reveal that the majority of genes up-regulated in MCMI-Mφ are associated with tumor invasion. The most strikingly up-regulated genes are CCL2 and MMP-9. Consistent with this, blockade of both CCL-2 and MMPs diminish MCMI-Mφ-induced melanoma invasion. Finally, we demonstrated that both MCMI-Mφ and in vivo TAMs express the pro-invasive, melanoma-associated gene, glycoprotein non-metastatic melanoma protein B. Our study provides a framework for understanding the mechanisms of cross-talk between TAMs and melanoma cells within the tumor microenvironment.