title: Dual inhibition of EGFR at protein and activity level via combinatorial blocking of PI4KIIα as anti-tumor strategy.
abstract: Our previous studies indicate that phosphatidylinositol 4-kinase IIα can promote the growth of multi-malignant tumors via HER-2/PI3K and MAPK pathways. However, the molecular mechanisms of this pathway and its potential for clinical application remain unknown. In this study, we found that PI4KIIα could be an ideal combinatorial target for EGFR treatment via regulating EGFR degradation. Results showed that PI4KIIα knockdown reduced EGFR protein level, and the expression of PI4KIIα shows a strong correlation with EGFR in human breast cancer tissues (r = 0.77, P < 0.01). PI4KIIα knockdown greatly prolonged the effects and decreased the effective dosage of AG-1478, a specific inhibitor of EGFR. In addition, it significantly enhanced AG1478-induced inhibition of tumor cell survival and strengthened the effect of the EGFR-targeting anti-cancer drug Iressa in xenograft tumor models. Mechanistically, we found that PI4KIIα suppression increased EGFR ligand-independent degradation. Quantitative proteomic analysis by stable isotope labeling with amino acids in cell culture (SILAC) and LC-MS/MS suggested that HSP90 mediated the effect of PI4KIIα on EGFR. Furthermore, we found that combined inhibition of PI4KIIα and EGFR suppressed both PI3K/AKT and MAPK/ERK pathways, and resulted in downregulation of multiple oncogenes like PRDX2, FASN, MTA2, ultimately leading to suppression of tumor growth. Therefore, we conclude that combined inhibition of PI4KIIα and EGFR exerts a multiple anti-tumor effect. Dual inhibition of EGFR at protein and activity level via combinatorial blocking of PI4KIIα presents a novel strategy to combat EGFR-dependent tumors.
authors.affiliation: National Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, 100101, China.
authors.forename: Jiangmei
authors.initials: J
authors.lastname: Li
authors.forename: Lunfeng
authors.initials: L
authors.lastname: Zhang
authors.forename: Zhen
authors.initials: Z
authors.lastname: Gao
authors.forename: Hua
authors.initials: H
authors.lastname: Kang
authors.forename: Guohua
authors.initials: G
authors.lastname: Rong
authors.forename: Xu
authors.initials: X
authors.lastname: Zhang
authors.forename: Chang
authors.initials: C
authors.lastname: Chen
mesh_terms: D000818:Animals; D000970:Antineoplastic Agents / Q000494:pharmacology; D001943:Breast Neoplasms / Q000378:metabolism / Q000473:pathology; D045744:Cell Line, Tumor; D002470:Cell Survival / Q000187:drug effects; D066246:ErbB Receptors / Q000037:antagonists & inhibitors / Q000378:metabolism*; D005260:Female; D018841:HSP90 Heat-Shock Proteins / Q000378:metabolism; D006801:Humans; D061986:MCF-7 Cells; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C; D008819:Mice, Nude; D015778:Minor Histocompatibility Antigens; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism; D017853:Phosphotransferases (Alcohol Group Acceptor) / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism; D011799:Quinazolines / Q000494:pharmacology; D014183:Transplantation, Heterologous; D020032:Tyrphostins / Q000494:pharmacology
chemical_list: D000970:Antineoplastic Agents; D018841:HSP90 Heat-Shock Proteins; D015778:Minor Histocompatibility Antigens; D011799:Quinazolines; D020032:Tyrphostins; C101044:RTKI cpd; D019869:Phosphatidylinositol 3-Kinases; D017853:Phosphotransferases (Alcohol Group Acceptor); C402182:phosphatidylinositol phosphate 4-kinase; C512478:EGFR protein, human; D066246:ErbB Receptors; D051057:Proto-Oncogene Proteins c-akt; D020928:Mitogen-Activated Protein Kinases