Inflammation and IGF‐I activate the Akt pathway in breast cancer

Abstract

Akt signaling may promote breast cancer progression and poor disease outcome. We hypothesized that serum insulin-like growth factor I (IGF-I) and a proinflammatory tumor environment induce phosphorylation of Akt and downstream targets of Akt in breast cancer. We studied the relationship between Akt pathway activation, IGF-I and markers of inflammation, e.g., nitric oxide synthase-2 (NOS2), cyclooxygenase-2 (COX2) and tumor phagocyte density, in 248 breast tumors. We also examined the association of Akt phosphorylation with breast cancer survival. We observed that phosphorylation of Akt, BAD and caspase-9 correlated strongly with the expression of the 2 proinflammatory enzymes, NOS2 and COX2, in breast tumors (p < 0.001; Spearman rank correlation). Both NOS2 and COX2 expression were independently associated with Akt phosphorylation in the multivariate analysis. Serum IGF-I concentrations and the IGF-I/IGFBP3 ratio correlated with Akt phosphorylation at Thr308 and Ser473 in breast tumors (p 0.05; Spearman rank correlation). The association with Akt phosphorylation at Thr308 remained statistically significant in the multivariate analysis. Akt pathway activation was not associated with overall survival in the unstratified analysis, but we observed a statistical interaction between Akt phosphorylation and tumor phagocyte density on breast cancer survival (p interaction < 0.05). We further corroborated our findings in cell culture models by demonstrating that ANA-1 macrophages, nitric oxide and prostaglandin E 2 induce Akt phosphorylation in human breast cancer cells. In summary, a proinflammatory environment was found to activate the Akt pathway in breast cancer, and may modify the association between the Akt phosphorylation status and breast cancer survival. ' 2006 Wiley-Liss, Inc.Key words: breast cancer; Akt; inflammation; insulin-like growth factor; survival The Akt family of serine/threonine protein kinases are putative oncogenes that enhance the survival of various cell types. 1,2 The 3 closely related Akt isoforms induce cell proliferation and soft agar growth, and disrupt the acinar architecture of human mammary cells, but do not induce transformation by themselves. 3-5 Akt activation requires 2 critical phosphorylation steps at Thr308 and Ser473. The phosphorylation is induced by ligand-mediated activation of growth factor receptors and receptor tyrosine kinases. Insulin-like growth factor I (IGF-I), insulin and the epidermal growth factor are ligands that activate Akt through the receptormediated pathway. 1,6 The phosphorylation of membrane-bound Akt establishes the full Akt kinase activity and induces Akt translocation into the cytosol and nucleus. 7-10 Activated Akt phosphorylates a number of downstream targets such as BAD, caspase-9, p21, p27, GSK3b, Mdm2, mTOR, IKKa and others. 1,11,12 The phosphorylation of BAD and caspase-9 blocks the apoptotic activity of the 2 proteins and raises the threshold for apoptosis. [13][14][15] Thus, tumors that show a high phosphorylation of BAD and caspase-9 may have a ...

ADHFE1 is a breast cancer oncogene and induces metabolic reprogramming

“…The peroxidase blocking agent, peroxidase-labeled polymer, and the chromogen were part of the Dako EnVision System kit (Agilent Technologies). ADHFE1 expression in the tumor epithelium was scored as negative, low, moderate, or high using a standard scoring system as previously described (12,57), and then categorized into low (negative to low) and high (moderate to high) for correlation and survival analysis. The IHC for E-cadherin was performed with the same general protocol but with the Dako mouse monoclonal anti-human E-cadherin antibody (clone NCH-38), 1:100 diluted.…”

The chemical biology of nitric oxide: Implications in cellular signaling

“…At sustained NO levels between 10-30 nM, phosphorylation of ERK occurs through a cGMP dependent mechanism in MCF7 and endothelial cells. At 30-60 nM NO Akt was phosphorylated 40,42,43 . When NO reaches a threshold concentration of about 100 nM, HIF-1α is stabilized 40 .…”

Increased NOS2 predicts poor survival in estrogen receptor–negative breast cancer patients

“…Thus, NO's effects in human solid tumors are difficult to predict and are best estimated from the expression analysis of nitric oxide synthase enzymes in these tumors and their association with tumor markers and survival. We and others have previously discovered that NOS2 expression correlates with increased Akt phosphorylation in breast tumors and that NO induces Akt phosphorylation and activation of the oncogenic Akt pathway in breast cancer cells in culture (21,22). Here, we tested the hypothesis that NOS2 is a predictor of breast cancer survival and examined the mechanism by which NO may induce a poor outcome phenotype.…”