EFFECTS OF BIOLOGICALLY-ACTIVE TUMOR-PROMOTING AND NONPROMOTING PHORBOL ESTERS ON INVITRO GROWTH OF MELANOCYTIC CELLS

Sapintoxin A (SAP A), a naturally occurring biologically active but non‐promoting phorbol ester, acts as an effective in vitro mitogen for freshly derived human melanocytes. Seven days after addition of 50 nM SAP A there was a four to fivefold increase in melanocyte number over that observed in untreated control cultures comparable to that achieved with a 50 nM concentration of 12‐0‐tetradecanoylphorbol 13‐acetate (TPA). The fluorescent stage 2 promoter sapintoxin D (SAP D) also supported the growth of these cells, with a 50 nM dose producing an increase in cell number comparable to that observed with 200 nM TPA. Similar results were obtained with an established, but non‐tumorigenic, line of murine melanocytes. The same compounds exerted a potent anti‐proliferative effect against transformed melanocyte lines of murine and human origin associated with morphological alterations and an increase in melanin production consistent with induced cytodifferentiation. Copyright © 1990, Wiley Blackwell. All rights reserved