Hypoxia-inducible factor-1α inhibition by a pyrrolopyrazine metabolite of oltipraz as a consequence of microRNAs 199a-5p and 20a induction.
Oltipraz, a cancer chemopreventive agent, has antitumor and antiangiogenic effects. In animal models and clinical studies, a considerable amount of oltipraz is metabolized to pyrrolopyrazines, including M2, 7-methyl-6,8-bis(methylthio)pyrrolo[1,2-a]pyrazine; M3, 7-methyl-8-(methylsulfinyl)-6-(methylthio)pyrrolo[1,2-a]pyrazine and M4, 7-methyl-6,8-bis(methylsulfinyl)pyrrolo[1,2-a]pyrazine. In view of the role of hypoxia-inducible factor-1 (HIF-1) α in tumor growth and angiogenesis, this study investigated whether pyrrolopyrazine metabolites of oltipraz inhibit HIF-1α induction, and if so, what the molecular basis is. M2 treatment inhibited the induction of HIF-1α by a variety of stimuli including insulin, hypoxia, CoCl(2) and hydrogen peroxide in HCT116 cells, whereas M3 or M4 failed to do so. Consistently, M2 prevented HIF-1α target gene induction. Moreover, it inhibited cancer cell invasion and migration. M2 caused no change in the expression of HIF-1α transcript but increased the levels of precursor forms of microRNAs (miRNAs) 199a-5p and 20a, but not those of primary forms, indicating facilitation of the maturation process of the miRNAs by M2. Increased levels of the miRNAs contributed to HIF-1α repression, as shown by the results of experiments using mimics. Consistently, M2 treatment inhibited de novo synthesis of HIF-1α, as supported by decreased incorporation of [(35)S]-methionine into HIF-1α with no changes in its ubiquitination or degradation. 7-Ethyl-6,8-bis(methylthio)pyrrolo[1,2-a]pyrazine, a synthetic analog of M2, had a similar inhibitory effect. In conclusion, M2 with pyrrolopyrazine structure and its 7-ethyl congenor have the ability to prevent the induction of HIF-1α, which may result from the inhibition of HIF-1α de novo synthesis, as mediated by the induction of miR-199a-5p and miR-20a.
Department of Pharmacy, College of Pharmacy, Seoul National University, Seoul 151-742, South Korea.
Seul Gi
SG
Kang
Woo Hyung
WH
Lee
Young Hun
YH
Lee
Yong Sup
YS
Lee
Sang Geon
SG
Kim
D015687:Cell Hypoxia; D045744:Cell Line, Tumor; D002465:Cell Movement / Q000187:drug effects; D003035:Cobalt / Q000494:pharmacology; D019073:HT29 Cells; D006801:Humans; D006861:Hydrogen Peroxide / Q000494:pharmacology; D051795:Hypoxia-Inducible Factor 1, alpha Subunit / Q000096:biosynthesis* / Q000235:genetics / Q000378:metabolism; D007328:Insulin / Q000494:pharmacology; D035683:MicroRNAs / Q000096:biosynthesis / Q000378:metabolism*; D009361:Neoplasm Invasiveness; D009389:Neovascularization, Pathologic / Q000235:genetics; D011719:Pyrazines / Q000378:metabolism* / Q000494:pharmacology*; D011724:Pyridazines / Q000494:pharmacology; D011758:Pyrroles / Q000494:pharmacology*; D013871:Thiones; D013876:Thiophenes
C571896:7-ethyl-6,8-bis(methylthio)pyrrolo(1,2-a)pyrazine; D051795:Hypoxia-Inducible Factor 1, alpha Subunit; D007328:Insulin; C534451:MIRN20a microRNA, human; D035683:MicroRNAs; D011719:Pyrazines; D011724:Pyridazines; D011758:Pyrroles; C508945:Pyrrolopyridazine; D013871:Thiones; D013876:Thiophenes; C531408:mirn199 microRNA, human; D003035:Cobalt; C026209:oltipraz; C094803:7-methyl-6,8-bis(methylthio)pyrrolo(1,2-a)pyrazine; D006861:Hydrogen Peroxide; C018021:cobaltous chloride