Mitogenic response of near-diploid mouse cell line m5S/1M induced by epidermal growth factor

✍ Scribed by Sachihiko Watanabe; Masato Umeda; Tomoko Nomura; Tetsuyuki Kobayashi; Tohoru Nakano; Hitoshi Arita; Hiroshi Utsumi; Masao S. Sasaki; Keizo Inoue

• Publisher: John Wiley and Sons
• Year: 1990
• Tongue: English
• Weight: 864 KB
• Volume: 142
• Category: Article
• ISSN: 0021-9541
• DOI: 10.1002/jcp.1041420113

✦ Synopsis

Abstract

A nonmalignant near‐diploid cell line m5s/1M, established by Sasaki and Kodama (J. Cell. Res., 131:114–122, 1987), was shown to respond to the epidermal growth factor (EGF). The m5s/1M cells showed high sensitivity to post‐confluence inhibition of cell division and formed a uniform monolayer after the cells had become confluent. The addition of EGF resulted in loss of contact‐dependent inhibition of growth and caused a massive piling up of a multilayered array of cells after they had become confluent. When EGF was removed from the medium, the cell number decreased rapidly, and the cells formed a uniform monolayer at the density observed in the absence of EGF. m5S/1M cells have high‐ and low‐affinity receptors for EGF (approximately 40,000 receptors per cell), and the apparent dissociation constants of the EGF‐binding reactions were 3.3 nM and 0.15 nM, respectively. The effect of EGF on the intracellular mobilization of Ca^2+^ and the formation of inositol phosphates was studied by using the calcium‐sensitive fluorescent indicator fura 2 and [^3^H]inositol. EGF had no effect either on the mobilization of cytosolic free calcium ([Ca^2+^]~i~) or on the formation of inositol phosphates in m5/1M cells, whereas bradykinin induced a rapid increase in both [Ca^2+^]~i~ and inositol phosphates. Analysis of the gly‐cosphingolipid (GSL) composition of m5S/1M cells showed that globotriaosyl‐ceramide (Gb~3~Cer), which is known to be a Burkitt lymphoma‐associated antigen, is specifically expressed in the EGF‐treated cells. The expression of Gb~3~Cer is dependent on the presence of EGF, with a reversible shift in GSL composition being observed in the presence or absence of EGF.