Mitogenic action of lysophosphatidic acid and phosphatidic acid on fibroblasts. Dependence on acyl-chain length and inhibition by suramin.
Lysophosphatidic acid (LPA) is a naturally occurring phospholipid with growth-factor-like activities [van Corven, Groenink, Jalink, Eichholtz & Moolenaar (1989) Cell 45, 45-54]. We have examined various structural analogues of LPA for their ability to stimulate DNA synthesis in quiescent fibroblasts. When the acyl-chain length is varied, the rank order of mitogenic potency is: 1-oleoyl LPA congruent to 1-palmitoyl LPA greater than 1-myristoyl LPA greater than 1-lauroyl LPA greater than 1-decanoyl LPA; the last compound shows almost no activity over the concentration range tested (1-100 microM). An ether-linked LPA (1-O-hexadecylglycerol 3-phosphate) has much decreased mitogenic activity as compared with the ester-linked analogue at concentrations less than 25 microM, and becomes cytotoxic at higher concentrations. Hexadecylphosphate, which lacks a glycerol backbone, has negligible activity. On a molar basis, diacyl phosphatidic acid (PA) is about equally potent as the corresponding LPA analogue, showing similar acyl-chain-length dependence; the data argue against the possibility that the mitogenic action of PA is due to contaminating traces of LPA. Although the short-chain analogues of LPA and PA fail to antagonize the action of long-chain (L)PAs, the polyanionic drug suramin inhibits LPA- and PA-induced, DNA synthesis in a reversible and dose-dependent manner, at concentrations [IC50 (concn. giving 50% inhibition) approximately 70 microM] that do not affect epidermal-growth-factor-induced DNA synthesis. Suramin appears to act in the early G0/G1 phase of the cell cycle, blocking immediate responses to LPA such as phosphoinositide hydrolysis. We conclude that both LPA and PA can function as growth-promoting phospholipids, with the fatty acid chain length being a major determinant of mitogenic potency.
van Corven
E J
EJ
Division of Cellular Biochemistry, The Netherlands Cancer Institute, Amsterdam.
van Rijswijk
A
A
Jalink
K
K
van der Bend
R L
RL
van Blitterswijk
W J
WJ
Moolenaar
W H
WH
D000818:Animals; D002455:Cell Division / Q000187:drug effects; D002460:Cell Line; D004261:DNA Replication / Q000187:drug effects*; D016232:Endothelins / Q000494:pharmacology; D004815:Epidermal Growth Factor / Q000494:pharmacology; D007700:Kinetics; D008246:Lysophospholipids / Q000037:antagonists & inhibitors / Q000494:pharmacology*; D010712:Phosphatidic Acids / Q000037:antagonists & inhibitors / Q000494:pharmacology*; D013329:Structure-Activity Relationship; D013498:Suramin / Q000494:pharmacology*; D013936:Thymidine / Q000378:metabolism
D016232:Endothelins; D008246:Lysophospholipids; D010712:Phosphatidic Acids; D013498:Suramin; D004815:Epidermal Growth Factor; D013936:Thymidine