Suppression of FoxO1 Activity by Long-Chain Fatty Acyl Analogs

Abstract

OBJECTIVEOveractivity of the Forkhead transcription factor FoxO1 promotes diabetic hyperglycemia, dyslipidemia, and acute-phase response, whereas suppression of FoxO1 activity by insulin may alleviate diabetes. The reported efficacy of long-chain fatty acyl (LCFA) analogs of the MEDICA series in activating AMP-activated protein kinase (AMPK) and in treating animal models of diabesity may indicate suppression of FoxO1 activity.RESEARCH DESIGN AND METHODSThe insulin-sensitizing and anti-inflammatory efficacy of a MEDICA analog has been verified in guinea pig and in human C-reactive protein (hCRP) transgenic mice, respectively. Suppression of FoxO1 transcriptional activity has been verified in the context of FoxO1- and STAT3-responsive genes and compared with suppression of FoxO1 activity by insulin and metformin.RESULTSTreatment with MEDICA analog resulted in total body sensitization to insulin, suppression of lipopolysaccharide-induced hCRP and interleukin-6–induced acute phase reactants and robust decrease in FoxO1 transcriptional activity and in coactivation of STAT3. Suppression of FoxO1 activity was accounted for by its nuclear export by MEDICA-activated AMPK, complemented by inhibition of nuclear FoxO1 transcriptional activity by MEDICA-induced C/EBPβ isoforms. Similarly, insulin treatment resulted in nuclear exclusion of FoxO1 and further suppression of its nuclear activity by insulin-induced C/EBPβ isoforms. In contrast, FoxO1 suppression by metformin was essentially accounted for by its nuclear export by metformin-activated AMPK.CONCLUSIONSSuppression of FoxO1 activity by MEDICA analogs may partly account for their antidiabetic anti-inflammatory efficacy. FoxO1 suppression by LCFA analogs may provide a molecular rational for the beneficial efficacy of carbohydrate-restricted ketogenic diets in treating diabetes.

Long-Chain Fatty Acid Analogues Suppress Breast Tumorigenesis and Progression

“…Suppression of MMTV-PyMT and HCC1954 cell survival by MEDICA is shown here to be partly accounted for by suppressing the STAT3 transduction pathway, in line with our previous reports in other cell types (26). Suppression of STAT3 in MMTV-PyMT and HCC1954 cells by MEDICA is reflected by decrease in phospho-STAT3(Tyr705) and in STAT3 transcriptional activity.…”

“…Cell proliferation was quantified using the Methylene Blue assay. Met-1 cells cultured in 24 plate were transfected with M67-TATA-TK-LUC (1 mg) reporter plasmid, expression plasmids for constitutive STAT3 (0.1 mg), and for CMV-b-galactosidase (0.1 mg), using jetPEI DNA transfection reagent (26). Following 8 hours, medium was changed and cells were treated for 24 hours with MEDICA as indicated.…”

“…Following 8 hours, medium was changed and cells were treated for 24 hours with MEDICA as indicated. Luciferase activity normalized to b-galactosidase was measured as previously described (26). HCC1954 cells (ATCC CRL-2338) were cultured in RPMI-1640 (Biological Industries) supplemented with penicillinstreptomycin solution and 10% FCS, and added MEDICA as indicated.…”

“…As such, MEDICA analogues may mimic allosteric activities of free/nonesterified LCFA, while avoiding their role as substrates for b-oxidation or esterification into lipids. Moreover, MEDICA analogues proved antidiabetic hypolipidemic efficacy in a series of obese diabetic animal models (22)(23)(24)26), prompting our interest in studying the efficacy of ketogenic diet and MEDICA in the breast cancer context.…”

AMP-activated protein kinase and ATP-citrate lyase are two distinct molecular targets for ETC-1002, a novel small molecule regulator of lipid and carbohydrate metabolism

“…Although reductions in FOXO1 protein levels were observed in rat liver and primary rat hepatocytes, protein levels did not change in response to ETC-1002 treatment in HepG2 cells. Zatara et al ( 106 ) showed that the LCFA analogs of the AMPK-activating MEDICA series reduced liver FOXO1 protein levels in Sprague-Dawley rats and suppressed the nuclear:cytosolic ratio in HepG2 cells in an AMPK-dependent manner. Additional investigations are required to determine whether ETC-1002 modulates FOXO1 nuclear localization in a similar manner or through a distinct mechanism linked to ACL inhibition.…”