title: The phosphatidylinositol-3-kinase inhibitor PX-866 overcomes resistance to the epidermal growth factor receptor inhibitor gefitinib in A-549 human non-small cell lung cancer xenografts.
abstract: Epidermal growth factor receptor (EGFR) inhibitors such as gefitinib show antitumor activity in a subset of non-small cell lung cancer (NSCLC) patients having mutated EGFR. Recent work shows that phosphatidylinositol-3-kinase (PI3-K) is coupled to the EGFR only in NSCLC cell lines expressing ErbB-3 and that EGFR inhibitors do not inhibit PI3-K signaling in these cells. The central role PI3-K plays in cell survival suggests that a PI3-K inhibitor offers a strategy to increase the antitumor activity of EGFR inhibitors in resistant NSCL tumors that do not express ErbB-3. We show that PX-866, a PI3-K inhibitor with selectivity for p110alpha, potentiates the antitumor activity of gefitinib against even large A-549 NSCL xenografts giving complete tumor growth control in the early stages of treatment. A-549 xenograft phospho-Akt was inhibited by PX-866 but not by gefitinib. A major toxicity of PX-866 administration was hyperglycemia with decreased glucose tolerance, which was reversed upon cessation of treatment. The decreased glucose tolerance caused by PX-866 was insensitive to the AMP-activated protein kinase inhibitor metformin but reversed by insulin and by the peroxisome proliferator-activated receptor-gamma activator pioglitazone. Prolonged PX-866 administration also caused increased neutrophil counts. Thus, PX-866, by inhibiting PI3-K signaling, may have clinical use in increasing the response to EGFR inhibitors such as gefitinib in patients with NSCLC and possibly in other cancers who do not respond to EGFR inhibition.
authors.affiliation: Arizona Cancer Center, University of Arizona, Tucson, USA.
authors.forename: Nathan T
authors.initials: NT
authors.lastname: Ihle
authors.forename: Gillian
authors.initials: G
authors.lastname: Paine-Murrieta
authors.forename: Margareta I
authors.initials: MI
authors.lastname: Berggren
authors.forename: Amanda
authors.initials: A
authors.lastname: Baker
authors.forename: Wendy R
authors.initials: WR
authors.lastname: Tate
authors.forename: Peter
authors.initials: P
authors.lastname: Wipf
authors.forename: Robert T
authors.initials: RT
authors.lastname: Abraham
authors.forename: D Lynn
authors.initials: DL
authors.lastname: Kirkpatrick
authors.forename: Garth
authors.initials: G
authors.lastname: Powis
mesh_terms: D000818:Animals; D000970:Antineoplastic Agents / Q000494:pharmacology*; D002289:Carcinoma, Non-Small-Cell Lung / Q000188:drug therapy* / Q000378:metabolism / Q000473:pathology; D019008:Drug Resistance, Neoplasm; D004791:Enzyme Inhibitors / Q000494:pharmacology; D066246:ErbB Receptors / Q000037:antagonists & inhibitors*; D000077156:Gefitinib; D005951:Glucose Tolerance Test; D006067:Gonanes / Q000494:pharmacology*; D006801:Humans; D006943:Hyperglycemia / Q000209:etiology; D007004:Hypoglycemic Agents / Q000494:pharmacology; D008175:Lung Neoplasms / Q000188:drug therapy / Q000378:metabolism / Q000473:pathology; D008297:Male; D008687:Metformin / Q000494:pharmacology; D051379:Mice; D016513:Mice, SCID; D009504:Neutrophils / Q000378:metabolism; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism; D000081082:Phosphoinositide-3 Kinase Inhibitors; D000077205:Pioglitazone; D011799:Quinazolines / Q000494:pharmacology*; D045162:Thiazolidinediones / Q000494:pharmacology; D014183:Transplantation, Heterologous; D014407:Tumor Cells, Cultured
chemical_list: D000970:Antineoplastic Agents; D004791:Enzyme Inhibitors; D066246:ErbB Receptors; D000077156:Gefitinib; D006067:Gonanes; D007004:Hypoglycemic Agents; D008687:Metformin; D019869:Phosphatidylinositol 3-Kinases; D000081082:Phosphoinositide-3 Kinase Inhibitors; D000077205:Pioglitazone; D011799:Quinazolines; D045162:Thiazolidinediones; C496788:PX-866