MYOMETRIAL CHARACTERISTICS OF THE SYRIAN-HAMSTER UTERINE SMOOTH-MUSCLE CELL-LINE, SHM

We describe several characteristics of a novel smooth muscle cell line , SHM (Syrian hamster myometrium) derived from a primary uterine leiom yosarcoma which was induced by chronic estrogen plus androgen treatmen t of a female Syrian (golden) hamster. To determine the usefulness of the SHM cell line as a model for understanding myometrial function and its regulation, we have examined the morphologic and immunocytochemic al properties of these cells, and the ability of uterotonic agonists t o activate transmembrane signaling via phosphoinositide hydrolysis. Th e SHM cells exhibited a spindle-shape, smooth musclelike morphology wh en subconfluent, and a more compact, stellate shape at confluence. Lik e primary myocytes, SHM cells expressed the intermediate filament desm in and the contractile protein alpha smooth muscle actin, but not the epithelial antigen cytokeratin. Norepinephrine and bradykinin, which s timulate contraction and inositol polyphosphate production in the uter us, also stimulated inositol polyphosphate production in SHM cells. Th e maximal phosphoinositide signaling responses were lower in SHM cells compared with primary hamster uterine myocytes. We conclude that the SHM cell line exhibits primary uterine myocyte characteristics, and ma y therefore be a useful system for examining the mechanisms through wh ich myometrial functions are regulated.