Antenatal Steroids and Cord Blood T-cell Glucocorticoid Receptor DNA Methylation and Exon 1 Splicing.

Antenatal administration of glucocorticoids such as betamethasone (BMZ) during the late preterm period improves neonatal respiratory outcomes. However, glucocorticoids may elicit programming effects on immune function and gene regulation. Here, we test the hypothesis that exposure to antenatal BMZ alters cord blood immune cell composition in association with altered DNA methylation and alternatively expressed Exon 1 transcripts of the glucocorticoid receptor (GR) gene in cord blood CD4+ T-cells. Cord blood was collected from 51 subjects in the Antenatal Late Preterm Steroids Trial: 27 BMZ, 24 placebo. Proportions of leukocytes were compared between BMZ and placebo. In CD4+ T-cells, methylation at CpG sites in the GR promoter regions and expression of GR mRNA exon 1 variants were compared between BMZ and placebo. BMZ was associated with an increase in granulocytes (51.6% vs. 44.7% p = 0.03) and a decrease in lymphocytes (36.8% vs. 43.0% p = 0.04) as a percent of the leukocyte population vs. placebo. Neither GR methylation nor exon 1 transcript levels differed between groups. BMZ is associated with altered cord blood leukocyte proportions, although no associated alterations in GR methylation were observed.

OSM potentiates preintravasation events, increases CTC counts, and promotes breast cancer metastasis to the lung.

BACKGROUND: Systemic and chronic inflammatory conditions in patients with breast cancer have been associated with reduced patient survival and increased breast cancer aggressiveness. This paper characterizes the role of an inflammatory cytokine, oncostatin M (OSM), in the preintravasation aspects of breast cancer metastasis. METHODS: OSM expression levels in human breast cancer tissue samples were assessed using tissue microarrays, and expression patterns based on clinical stage were assessed. To determine the in vivo role of OSM in breast cancer metastasis to the lung, we used three orthotopic breast cancer mouse models, including a syngeneic 4T1.2 mouse mammary cancer model, the MDA-MB-231 human breast cancer xenograft model, and an OSM-knockout (OSM-KO) mouse model. Progression of metastatic disease was tracked by magnetic resonance imaging and bioluminescence imaging. Endpoint analysis included circulating tumor cell (CTC) counts, lung metastatic burden analysis by qPCR, and ex vivo bioluminescence imaging. RESULTS: Using tissue microarrays, we found that tumor cell OSM was expressed at the highest levels in ductal carcinoma in situ. This finding suggests that OSM may function during the earlier steps of breast cancer metastasis. In mice bearing MDA-MB-231-Luc2 xenograft tumors, peritumoral injection of recombinant human OSM not only increased metastases to the lung and decreased survival but also increased CTC numbers. To our knowledge, this is the first time that a gp130 family inflammatory cytokine has been shown to directly affect CTC numbers. Using a 4T1.2 syngeneic mouse model of breast cancer, we found that mice bearing 4T1.2-shOSM tumors with knocked down tumor expression of OSM had reduced CTCs, decreased lung metastatic burden, and increased survival compared with mice bearing control tumors. CTC numbers were further reduced in OSM-KO mice bearing the same tumors, demonstrating the importance of both paracrine- and autocrine-produced OSM in this process. In vitro studies further supported the hypothesis that OSM promotes preintravasation aspects of cancer metastasis, because OSM induced both 4T1.2 tumor cell detachment and migration. CONCLUSIONS: Collectively, our findings suggest that OSM plays a crucial role in the early steps of metastatic breast cancer progression, resulting in increased CTCs and lung metastases as well as reduced survival. Therefore, early therapeutic inhibition of OSM in patients with breast cancer may prevent breast cancer metastasis.