Nelfinavir-induced insulin resistance is associated with impaired plasma membrane recruitment of the PI 3-kinase effectors Akt/PKB and PKC-?

Abstract

Aims/hypothesis. Chronic exposure of 3T3-L1 adipocytes to the HIV protease inhibitor nelfinavir induces insulin resistance, recapitulating key metabolic alterations of adipose tissue in the lipodystrophy syndrome induced by these agents. Our goal was to identify the defect in the insulin signal transduction cascade leading to nelfinavir-induced insulin resistance. Methods. Fully differentiated 3T3-L1 adipocytes were exposed to 30 µmol/l nelfinavir for 18 h, after which the amount, the phosphorylation and the localisation of key proteins in the insulin signalling cascade were evaluated.Results. Insulin-induced interaction of phosphatidylinositol 3′-kinase (PI 3-kinase) with IRS proteins was normal in cells treated with nelfinavir, as was IRS-1-associated PI 3-kinase activity. Yet insulin-induced phosphorylation of Akt/protein kinase B (PKB), p70S6 kinase and extracellular signal-regulated kinase 1/2 was significantly impaired. This could not be attributed to increased protein phosphatase 2A activity or to increased expression of phosphoinositide phosphatases (SHIP2 or PTEN). However, insulin failed to induce translocation of the PI 3-kinase effectors Akt/PKB and protein kinase C-ζ (PKC-ζ) to plasma membrane fractions of nelfinavir-treated adipocytes. Conclusions/interpretation. We therefore conclude that nelfinavir induces a defect in the insulin signalling cascade downstream of the activation of PI 3-kinase. This defect manifests itself by impaired insulin-mediated recruitment of Akt/PKB and PKC-ζ to the plasma membrane.

Nelfinavir, A Lead HIV Protease Inhibitor, Is a Broad-Spectrum, Anticancer Agent that Induces Endoplasmic Reticulum Stress, Autophagy, and Apoptosis In vitro and In vivo

“…Other groups have reported that nelfinavir decreases phosphorylation of Akt at S473 in cancer cell lines, but only after 1 or 3 days of incubation (26,29). In addition, other studies have shown that HIV protease inhibitors can inhibit insulin-stimulated Akt activation (26,38,39). Our study extends these observations by showing that nelfinavir reduces Akt activation in response to EGF or IGF-I, and that decreased Akt stimulation correlates with decreased receptor tyrosine kinase activation.…”

NFV, an HIV-1 protease inhibitor, induces growth arrest, reduced Akt signalling, apoptosis and docetaxel sensitisation in NSCLC cell lines

“…Insulin activates the PI3-K/ Akt signalling, which stimulates glucose transport in adipose and muscle cells (Grinspoon, 2001). Recent studies showed that NFV blocked insulin-induced translocation of Akt to plasma membrane, where PI3-K phosphorylates Akt, resulting in inactivation of Akt (Ben-Romano et al, 2004). It could be the same as NFV inactivates Akt in NSCLC cells.…”

Insulin resistance induced by antiretroviral drugs: Current understanding of molecular mechanisms

“…In this particular study, nelfinavir at 30 µM induced insulin resistance in 3T3-L1 adipocytes by inhibiting recruitment and activation of PI3-K, leading to impaired GLUT4 translocation and thus preventing insulinstimulated glucose uptake. 27,28 These effects were not accompanied by changes in insulin receptor expression or insulin receptor tyrosine phosphorylation. 27 More recently, the effects of nelfinavir were studied in 3T3-L1 adipocytes expressing a GLUT4-green fluorescent protein (GFP) fusion protein to analyse transporter movement.…”

“…27,28 These effects were not accompanied by changes in insulin receptor expression or insulin receptor tyrosine phosphorylation. 27 More recently, the effects of nelfinavir were studied in 3T3-L1 adipocytes expressing a GLUT4-green fluorescent protein (GFP) fusion protein to analyse transporter movement. Fusion of GLUT4 to GFP allows real time visualisation of glucose transporter movement under a fluorescent microscope.…”