VSMCs from a postmenopausal donor were transfected with MT1-MMP or negative control siRNAs, treated with estrogen (Est), analyzed by q-PCR, Western blot, zymography, migration, invasion, and proliferation assays.
Est treatment of MT1-MMP silenced cells still resulted in increased MT1-MMP expression (C = 41%卤 4%; Est = 52%卤 2%; P < 0.05). Silencing of MT1-MMP decreased basal MMP-2 activity (nonsilenced = 100%; MT1-silenced = 87%卤 3%; P < 0.05) but had no effect on basal invasion or proliferation. Est treatment of MT1-MMP silenced cells still resulted in increased MMP-2 activity (C = 87%卤 3%; Est = 101%卤 4%; P < 0.05) and invasion (C = 89%卤 6%; Est = 109%卤 3%; P聽< 0.05) compared with MT1-MMP silenced control cells. However, silencing of MT1-MMP did inhibit Est- and serum-stimulated proliferation (C = 106%卤 18%; Est = 104%卤 16%; FBS = 121%卤 24%; P = NS).
Silencing of MT1-MMP in aged VSMCs results in impaired but not complete inhibition of basal and Est-stimulated increases in MMP-2 activity. Other mechanisms appear to be playing a role in hormonally-regulated cellular processes of IH pathogenesis. Future studies will target other signaling cascades, with the goal of identifying mechanisms responsible for hormonally-modulated unbalanced MMPs. In vivo manipulation of the expression patterns聽of MT1-MMP will be examined for the prevention of IH in animal models of vascular disease.