title: G0S2 is an all-trans-retinoic acid target gene.
abstract: All-trans-retinoic acid (RA) treatment of acute promyelocytic leukemia (APL) cases expressing the t(15;17) product, PML/RARalpha, is a successful example of differentiation therapy. Uncovering RA target genes is of considerable interest in APL. This study comprehensively examines in APL cells transcriptional and post-transcriptional regulation of the novel candidate RA target gene, G0S2, the G0/G1 switch gene. Reverse transcription (RT)-polymerase chain reaction (PCR) and heteronuclear PCR assays performed +/- treatment with the protein synthesis inhibitor cycloheximide (CHX) revealed G0S2 induction within 3 h of RA-treatment. Treatment with the RNA synthesis inhibitor actinomycin D did not implicate G0S2 transcript stabilization in the RA-mediated increase of G0S2 mRNA expression. Promoter elements of G0S2 were cloned into a reporter plasmid and retinoic acid receptor (RAR) co-transfection assays confirmed transcriptional activation after RA-treatment. Consistent with G0S2 being a direct RA target gene, retinoic acid response element (RARE) half-sites were found in this promoter. Mutation of these sites blocked RA-transcriptional activation of G0S2. To extend analyses to the protein expression level, a polyclonal anti-G0S2 antibody was derived and detected murine and human G0S2 species. G0S2 protein was rapidly induced in cultured NB4-S1 human APL cells and in APL transgenic mice treated with RA. An RAR pan-antagonist confirmed dependence on RARs for this induction. That these findings are clinically relevant was shown by analyses of APL cells derived directly from patients. These leukemic cells induced both a prominent increase in the cellular differentiation marker nitrotetrazolium blue (NBT) staining and marked increase in G0S2 expression. Taken together, these findings indicate G0S2 is an RA target gene. The functional role of G0S2 in retinoid response of APL warrants further study.
authors.affiliation: Department of Pharmacology and Toxicology, Dartmouth Medical School, Hanover, NH 03755, USA.
authors.forename: Sutisak
authors.initials: S
authors.lastname: Kitareewan
authors.forename: Steven
authors.initials: S
authors.lastname: Blumen
authors.forename: David
authors.initials: D
authors.lastname: Sekula
authors.forename: Reid P
authors.initials: RP
authors.lastname: Bissonnette
authors.forename: William W
authors.initials: WW
authors.lastname: Lamph
authors.forename: Qingping
authors.initials: Q
authors.lastname: Cui
authors.forename: Robert
authors.initials: R
authors.lastname: Gallagher
authors.forename: Ethan
authors.initials: E
authors.lastname: Dmitrovsky
mesh_terms: D000818:Animals; D000970:Antineoplastic Agents / Q000494:pharmacology*; D018797:Cell Cycle Proteins / Q000187:drug effects* / Q000235:genetics* / Q000378:metabolism; D045744:Cell Line, Tumor; D015870:Gene Expression / Q000187:drug effects; D006801:Humans; D015151:Immunoblotting; D015473:Leukemia, Promyelocytic, Acute / Q000235:genetics / Q000378:metabolism; D051379:Mice; D008822:Mice, Transgenic; D020411:Oligonucleotide Array Sequence Analysis; D011401:Promoter Regions, Genetic / Q000187:drug effects / Q000235:genetics; D012333:RNA, Messenger / Q000032:analysis; D018168:Receptors, Retinoic Acid / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014212:Tretinoin / Q000494:pharmacology*; D030181:Vitamin D Response Element / Q000187:drug effects / Q000502:physiology
chemical_list: D000970:Antineoplastic Agents; D018797:Cell Cycle Proteins; C508073:G0S2 protein, human; D012333:RNA, Messenger; D018168:Receptors, Retinoic Acid; D014212:Tretinoin