Purpose: Our previous studies have shown that oncostatin M (OSM) promotes trophoblast invasion activity through increased enzyme activity of matrix metalloproteinase (MMP)-2 and -9. We further investigated OSM-induced intracellular signaling mechanisms associated with these events in the immortalized human trophoblast cell line HTR8/SVneo.
Materials and methods: We investigated the effects of OSM on RNA and protein expression of MMP-2 and -9 in the first-trimester extravillous trophoblast cell line (HTR8/SVneo) via Western blot. The selective signal transducer and activator of transcription (STAT)3 inhibitor, stattic, STAT3 siRNA, and extracellular signal-regulated kinase (ERK) siRNA were used to investigate STAT3 and ERK activation by OSM. The effects of STAT3 and ERK inhibitors on OSM-induced enzymatic activities of MMP-2 and -9 and invasion activity were further determined via Western blot and gelatin zymography.
Results: OSM-induced MMP-2 and -9 protein expression was significantly suppressed by STAT3 inhibition with stattic and STAT3 siRNA silencing, whereas the ERK1/2 inhibitor (U0126) and ERK silencing significantly suppressed OSM-induced MMP-2 protein expression. OSM-induced MMP-2 and MMP-9 enzymatic activities were significantly decreased by stattic pretreatment. The increased invasion activity induced by OSM was significantly suppressed by STAT3 and ERK1/2 inhibition, though to a greater extent by STAT3 inhibition.
Conclusion: Both STAT3 and ERK signaling pathways are involved in OSM-induced invasion activity of HTR8/SVneo cells. Activation of STAT3 appears to be critical for the OSM-mediated increase in invasiveness of HTR8/SVneo cells.
Keywords: Oncostatin M; extracellular signal-regulated kinases (ERK)1/2; signal transducer and activator of transcription (STAT)3; signaling pathway; trophoblasts.