A NOVEL STEROIDOGENIC ROLE OF SURAMIN-BLOCKED LUTEAL CELL-GROWTH FACTORS

Growth factors synthesized in the ovarian corpus luteum (CL) have been implicated in the development of the CL. One of these growth factors is basic fibroblast growth factor which acts on luteal cells in an aut ocrine manner (Tamura et al. 1991 ; Asakai et al. 1992). To elucidate effects of these growth factors in the development of the CL, we cultu red immature luteal cells with. defined medium for a week in the prese nse or absence of a growth factor inhibitor, and measured progesterone in the medium as an indicator of cell differentiation. Culture of lut eal cells showed an increased amount of progesterone for three days an d continued to synthesize progesterone for at least another four days without serum and pituitary hormones. The addition of suramin, previou sly reported to inhibit autocrine growth stimulation, accelerate the d aily progesterone production of luteal cells apparently by switching o n the early onset of differentiation. Suramin also induced apoptosis o f the cells after the 3rd day of culture. These data suggest that an a utostimulation mechanism by growth factors plays a physiological role on normal cell differentiation, and it is not limited to neoplastic au totransformation.