Oncostatin M Regulation of Gene Expression in Breast Tumour Cells.

Oncostatin m (OSM) induces potent growth inhibitory and morphogenic responses in several different tumour cell types but the genetic events are not well understood. OSM can signal through two separate heterodimeric receptor complexes, gp130/LIFRα and gp130/OSMRβ. In this investigation we utilised cytokines, oncostatin M, interleukin-6 (IL-6) and leukaemia inhibitory factor (LIF) and LIF receptor antagonist, LIF-05, to help identify patterns of gene expression elicited by the different IL-6 receptor complexes in breast tumour cell line, T47D . We have tried to identify an OSM gene signature common to multiple breast tumour-derived cell lines (T47D, MCF-7 and MDA-MB-231) and identified OSM-gene regulation at time-points which coincide with the onset of OSM-induced biological effects. These findings identify a core transcriptional mechanism specific to the OSMRβ in breast tumour cells. Keywords: Comparative, timecourse, cell line-specific The first aim was to identify OSM-specific gene expression events at early time-points (30 and 60 minutes) in T47D breast tumour cells and compare these against gene expression regulated by IL-6 (30 and 60 minutes) and LIF (60 minutes) respectively. Arrays performed included: (A) unstimulated versus OSM + LIF-05 (B) unstimulated versus OSM (C) unstimulated versus IL-6 (D) unstimulated versus LIF (E) unstimulated versus LIF-05 This allowed gene expression arising from stimulation of gp130/OSMRβ (A) or gp130/LIFRα and gp130/OSMRβ (B) to be assessed and compared with expression arising from stimulation of gp130/gp130 (C) and gp130/LIFRα (D) receptor complexes. The LIF receptor antagonist, which blocks OSM-induced gp130/LIFRα signalling, was also assessed for aberrant gene activity (E). For each condition two replicate arrays were performed (dye swap). This gives a total of 16 arrays. Secondly, gene expression resulting from OSM stimulation was identified at extended time-points (180 minutes, 1 day, 3 days and 6 days) and also included dye-swap replicate arrays. A further 8 arrays were performed. Finally, gene expression resulting from 60 minutes OSM stimulation of T47D, MCF-7 and MDA-MB-231 breast tumour cell lines was compared (including dye-swap replicates). A further 4 arrays were performed (MCF-7 and MDA-B-321).