Influence of serum supplements in culture medium on gonadotropin-releasing hormone effects on colony formation

Abstract

A number of studies have demonstrated that GnRH has anti-proliferative effects on various carcinomas of breast, ovary, endometrium, prostate, pancreas, and liver origin [1–17]. In contrast, GnRH increases the proliferative activity of lymphoid tissues and cells, which suggests that GnRH is also an important immunomodulator [18–22]. In a previous study, we demonstrated that the colony-forming efficiencies of HHUA (derived from human endometrial carcinoma) and Jurkat (derived from human mature leukemia) cells are affected by the GnRH agonist Buserelin, and that the conditioned media of HHUA and Jurkat cells severely affect the Buserelin activity [23]. The latter finding suggests that substances in the culture medium have some relation to the GnRH activity. Therefore, in the present study, to evaluate the effect of serum supplements on the colony-forming efficiency assay, the assay was performed using 3 lots of fetal bovine serum (FBS) and 2 lots of Nu-Serum I, a semi-synthetic serum supplement. The results showed that the colony-forming efficiencies of HHUA and Jurkat cells fluctuated greatly depending on the lot of FBS. In contrast, Buserelin significantly affected the colony-forming efficiency to similar extents in the media containing both the lots of Nu-Serum I. These results strongly suggest that the constituents of the serum supplements also influence the effect of GnRH on cell proliferation. For further studies about the relationship between substances in the culture medium and the GnRH effects on cell proliferation, it will be necessary to use a completely defined medium, and that a semi-synthetic serum supplement such as Nu-Serum I will also be useful.