A molecular analysis of PGE receptor (EP) expression on normal and transformed B lymphocytes: coexpression of EP1, EP2, EP3beta and EP4.
The E-series prostaglandins (PGEs) are complex lipid regulators of B lymphocyte function. They inhibit the growth of certain B lymphoma lines. We report that heterogeneity with respect to PGE-induced growth inhibition correlates with the maturation state of the B cell lines. Specifically, the pre-B cell line 70Z/3 and the immature lymphoma CH31 are extremely sensitive to PGE2. To a lesser degree, other immature lymphomas (CH33, ECH408.1 and WEHI-231) are sensitive to PGE2. More mature lymphomas (BAL-17, CH12 and CH27) and fully differentiated myelomas (J558 and MOPC-315) are insensitive to PGE2. It is unknown what subtype of PGE receptor(s) (EPs) are expressed by B lymphocytes. It is also unknown if modulation of EP receptor expression could account for the differences in the sensitivity of these B cell lines to PGE2. To investigate these issues, reverse transcriptase polymerase chain reaction, Northern blot and DNA sequencing analyses were employed to obtain a definitive EP receptor subtype profile for these B cell lines, and for normal splenic B lymphocytes. Both normal and transformed B lymphocytes express mRNA encoding EP1, EP3beta and EP4 subtypes of PGE receptors. The B lineage cells do not express EP3alpha nor EP3gamma mRNA. The B cell lines are clonal, indicating that EP1, EP3beta and EP4 mRNA are coexpressed. Surprisingly, quantitative differences in basal EP1, EP3beta and EP4 expression were not observed between B cell lines despite their differing susceptibilities to PGE-induced growth inhibition. Conversely, the polyclonal activator LPS selectively upregulates EP4 mRNA expression in the mature B cell line CH12, but not in the LPS-sensitive pre-B cell line, 70Z/3. The activator LPS does not affect EP1 nor EP3beta mRNA expression. Treatment with dbcAMP, an analog of cAMP, mimics PGE-induced growth inhibition indicating that Gs-coupled EP2 and/or EP4 receptors mediate this inhibitory signal. Indeed, EP2 agonists mimic PGE2-induced growth inhibition unlike IP, EP1 and EP3-selective agonists. These data indicate that EP2 receptors are sufficient for mediating PGE-induced growth inhibition of susceptible B lineage cells.
Fedyk
E R
ER
Immunology and Thoracic Oncology Programs of the Cancer Center, University of Rochester School of Medicine and Dentistry, Rochester, NY 14642, USA.
Ripper
J M
JM
Brown
D M
DM
Phipps
R P
RP
D000527:Alprostadil / Q000031:analogs & derivatives / Q000494:pharmacology; D000818:Animals; D001402:B-Lymphocytes / Q000378:metabolism*; D001483:Base Sequence; D003994:Bucladesine / Q000494:pharmacology; D002460:Cell Line; D017931:DNA Primers / Q000737:chemistry; D015232:Dinoprostone / Q000494:pharmacology; D015870:Gene Expression; D006131:Growth Inhibitors / Q000494:pharmacology; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D008811:Mice, Inbred DBA; D016595:Misoprostol / Q000494:pharmacology; D008969:Molecular Sequence Data; D012333:RNA, Messenger / Q000235:genetics; D018078:Receptors, Prostaglandin E / Q000819:agonists / Q000145:classification / Q000378:metabolism*; D013154:Spleen / Q000166:cytology
D017931:DNA Primers; D006131:Growth Inhibitors; D012333:RNA, Messenger; D018078:Receptors, Prostaglandin E; D016595:Misoprostol; D003994:Bucladesine; D000527:Alprostadil; C048491:butaprost; D015232:Dinoprostone