Sampangine Inhibits Heme Biosynthesis in both Yeast and Human

Abstract

The azaoxoaporphine alkaloid sampangine exhibits strong antiproliferation activity in various organisms. Previous studies suggested that it somehow affects heme metabolism and stimulates production of reactive oxygen species (ROS). In this study, we show that inhibition of heme biosynthesis is the primary mechanism of action by sampangine and that increases in the levels of reactive oxygen species are secondary to heme deficiency. We directly demonstrate that sampangine inhibits heme synthesis in the yeast Saccharomyces cerevisiae. It also causes accumulation of uroporphyrinogen and its decarboxylated derivatives, intermediate products of the heme biosynthesis pathway. Our results also suggest that sampangine likely works through an unusual mechanism-by hyperactivating uroporhyrinogen III synthase-to inhibit heme biosynthesis. We also show that the inhibitory effect of sampangine on heme synthesis is conserved in human cells. This study also reveals a surprising essential role for the interaction between the mitochondrial ATP synthase and the electron transport chain.

An extended set of yeast-based functional assays accurately identifies human disease mutations

“…Under this model, the disease-causing HsUROS variants alleviate this growth defect by decreasing enzymatic activity and/or expression, while still maintaining an activity that is sufficient to support growth. This model is supported by two previous studies: (1) a systematic study showing that overexpression of the ScHEM4 gene reduces growth rate (Sopko et al 2006); and (2) a study suggesting that the azaoxoaporphine alkaloid sampangine inhibits heme synthesis by hyperactivating the ScHEM4 gene (Huang et al 2011). The latter study showed that either sampagine treatment or ScHEM4 overexpression causes a growth defect that is remediable by heme supplementation.…”

Heme deficiency sensitizes yeast cells to oxidative stress induced by hydroxyurea

“…Earlier studies suggest that in addition to broken forks, HU may also kill the cells by generating oxidative stress (26 -29). Treatment of human leukemia cell lines with the heme synthesis inhibitor sampangine (SMP) has been reported to generate reactive oxygen species (ROS) and to induce apoptosis (30,31). Because of the potential defect in heme biosynthesis in hem13-1 cells, we surmised that the cell death induced by HU might be caused by accumulated ROS inside the mutant cells.…”

Discovering Thiamine Transporters as Targets of Chloroquine Using a Novel Functional Genomics Strategy

“…Yeast media used in this study include a haploid selection synthetic complete medium SC−Leu−His−Arg+G418+canavanine [46] and a synthetic complete (SC) medium that either contained or lacked uracil (SC-Ura) or leucine (SC-Leu). Amodiaquine dihydrochloride, Chloroquine diphosphate, mefloquine hydrochloride, primaquine bisphosphate, pyrithiamine hydrobromide, quinacrine dihydrochloride, quinine, quinidine, thiamine hydrochloride, and ferric chloride were all purchased from Sigma.…”

“…Genome-wide DGSL screens and subsequent individual validation were carried out as previously described [46], [47]. 5 mM of CQ was used in the screen.…”