Fig. 4

RARRES2 regulates lipid metabolism in MDA-MB-231 cells. a Correlation heatmap shows the lipid profiles between shRARRES2-2 and shControl MDA-MB-231 cells detected by untargeted lipidomic analysis. b Volcano plot showing the differentially expressed lipid metabolites in shRARRES2 in comparison to shControl samples. Blue and red circles represent lipid species that were significantly downregulated and upregulated, respectively, in shRARRES2 cells. c Relative differences in the content of lipid species between shRARRES2 and shControl MDA-MB-231 cells. d Metabolic pathways that were significantly upregulated in shRARRES2 MDA-MB-231 cells, based on our lipidomic profiling and the KEGG human metabolome database. e Heatmap of lipid metabolism genes differentially expressed between RARRES2-OE and control MDA-MB-231 cells. Each column in the matrix corresponds to a sample. Blue squares indicate genes downregulated in RARRES2-OE cells; red squares indicate genes upregulated in RARRES2-OE cells. f mRNA levels of ACACA and HMGCR in shRARRES2-1 and shControl MDA-MB-231 cells were examined by RT-qPCR. Levels of mRNA were normalized to those of GAPDH. ^**P = 0.006, ^***P = 0.0007, ^****P < 0.0001 (two-tailed unpaired-samples t test). g Viability of shRARRES2-2 and control MDA-MB-231 cells treated with 10 μmol/L etomoxir. The differences were tested for their significance using two-way ANOVA with Geisser-Greenhouse correction: ^**P = 0.0079. RARRES2 retinoic acid receptor responder 2, KEGG Kyoto Encyclopedia of Genes and Genomes, ACACA acetyl-CoA carboxylase alpha, HMGCR hydroxymethylglutaryl-CoA reductase, RT-qPCR real-time quantitative polymerase chain reaction, Car acylcarnitine, BMP bismonoacylglycerophosphate, CE cholesteryl ester, Cer_NDS ceramide non-hydroxyfatty acid-dihydrosphingosine, Cer_NS ceramide non-hydroxyfatty acid-sphingosine, CL cardiolipin, DG diacylglycerol, DGTS/A diacylglyceryl trimethylhomoserine/diacylglyceryl hydroxymethyl-N,N,N-trimethyl-β-alanine, HexCer_NDS hexosylceramide non-hydroxyfatty acid-sphingosine, HexCer_NS hexosylceramide non-hydroxyfatty acid-dihydrosphingosine, LPC lysophophatidylcholine, LPE lysophosphatidylethanolamine, PC phosphatidylcholine, PE phosphatidylethanolamine, PEtOH phosphatidylethanol, PG phosphatidylglycerol, PMeOH phosphatidylmethanol, SM sphingomyelin, SQDG sulfoquinovosyl diacylglycerol, TAG triacylglycerol, RARRES2-OE RARRES2 overexpression, ns non-significant