Fig. 5: PARP-AMPK-regulated SRC protects MEKi-induced metabolic stress.

A Gene set enrichment analysis (GSEA) showed that downregulation of ERK1/2 significantly decreased transcriptional signatures of glycolysis, oxidative phosphorylation, and fatty acid metabolism. The GEO dataset GSE21750 was used for GSEA. B p-ACC (Ser79) protein level negatively correlates with p-MEK1 but positively with PARP1 in MPM patients. The protein expression data [reverse-phase protein array (RPPA)] were downloaded from The Cancer Proteome Atlas (TCPA) portal (https://tcpaportal.org/). C Immunoblots of BE261T cells transfected (72 h) with si-MAP2K1 or scrambled siRNAs. D Respirometric measure (n = 3) of basal respiration (BR) and spare respiration capacity (SRC) in MESO1 cells treated with MEKi (0.5 μM trametinib) and PARPi (5 μM olaparib) for 72 h. *p < 0.05 by paired t-test. E Quantification of mitochondrial oxidative phosphorylation (OXPHOS) in MESO-1 cells treated with DMSO, PARPi, MEKi, and the combination. *p < 0.05 by paired t-test (n = 3). F Quantification of spare respiratory capacity (SRC) in MESO-1 cells treated with DMSO, AMPK inhibitor (AMPKi), and the combination of PARPi and AMPK activator (AMPKa). *p < 0.05 by paired t-test (n = 3). G, H Viability (72 h; G) and clonogenic (1 week; H) assay of MPM cells treated with MEKi (0.5 μM), in the presence or absence of compound C (5 μM). Shown in the insert (G) are immunoblots of BE261T cells treated with DMSO or compound C for 12 h. *p < 0.05, **p < 0.01, by Welch’s t-test. I Immunoblots of MESO1 cells starved (60 min) and co-treated (60 min) with compound C (AMPKi; 5 µM), AICAR (AMPKa; 1 mM), and olaparib (PARPi; 5 µM). Quantification of phospho-proteins was normalized to its total protein and the β-actin.