title: [Molecular mechanism of chemosensitization to paclitaxel in human melanoma cells induced by targeting the EGFR signaling pathway].
abstract: OBJECTIVE
  To study the molecular mechanism of epidermal growth factor receptor (EGFR) signaling pathway in mediating paclitaxel-resistance and improving paclitaxel sensitivity in human melanoma A375 cells.
  
  
  METHODS
  Human melanoma cell line A375 cells were treated with different concentrations of paclitaxel with or without 20 µmol/L AG1478 (EGFR inhibitor), 40 µmol/L PD98059 (extracellular signal conditioning kinase (ERK) 1/2 blockers) or 10 µmol/L LY294002 (PI3K inhibitor). MTT method was used to measure the proliferation of A375 cells. Flow cytometry was used to detect cell cycle and apoptosis in the A375 cells. The expressions of P-EGFR, P-ERK and P-AKT proteins were determined by Western blot analysis.
  
  
  RESULTS
  Paclitaxel (0.001 µmol/L to 0.1 µmol/L) inhibited the growth of A375 cells (P < 0.01) and induced apoptosis (P < 0.05) in a dose- and time-dependent manner. AG1478 (20 µmol/L) increased the 0.01 µmol/L paclitaxel-induced inhibition rate from 38.5% to 62.6% at 72 h. Different doses of paclitaxel induced apoptosis in A375 cells by different ways, in which G0/G1 phase cells were decreased and mitotic phase was prolonged at 0.01 µmol/L, and cell cycle arrest at G2/M phase by 0.1 µmol/L paclitaxel. When DNA damage occurred in A375 cells exposed to paclitaxel, expression of P-EGFR, P-ERK and P-AKT proteins was increased. When EGFR signaling pathway was blocked, paclitaxel did not activate MAPK signaling pathway or PI3K/AKT signaling pathway and did not change its effect on cell cycle in vitro. When EGFR was inhibited by 20 µmol/L tyrophostin AG1478, the 0.001 and 0.01 µmol/L paclitaxel-induced early apoptosis rate in A375 cells was increased by 1.73- and 1.80-fold, respectively. When the ERK signaling was blocked by 40 µmol/L PD98059, the 0.001 and 0.01 µmol/L paclitaxel-induced early apoptosis rate in A375 cells was increased by 2.73- and 2.25-fold, respectively. When the AKT signaling was blocked by 10 µmol/L LY294002, the 0.001 and 0.01 µmol/L paclitaxel-induced early apoptosis rate in A375 cells was increased by 2.02- and 1.46-fold, respectively.
  
  
  CONCLUSIONS
  Human melanoma A375 cells produce resistance to paclitaxel (0.001 to 0.1 µmol/L) by activating MAPK signaling and PI3K/AKT signaling pathways. Targeting EGFR, ERK and AKT signaling pathways significantly enhances the cytotoxic effect of paclitaxel on human melanoma cells.
authors.affiliation: Department of Bone and Soft Tissue Tumors, Liaoning Tumor Hospital, Clinical Cancer Institute, Dalian Medical University, Shenyang 110042, China.
authors.forename: Xiao-jing
authors.initials: XJ
authors.lastname: Zhang
authors.forename: Liang
authors.initials: L
authors.lastname: Zhang
authors.forename: Yun-peng
authors.initials: YP
authors.lastname: Liu
authors.forename: Hui-mian
authors.initials: HM
authors.lastname: Xu
authors.forename: Ping
authors.initials: P
authors.lastname: Sun
authors.forename: Jin-gang
authors.initials: JG
authors.lastname: Song
authors.forename: Ya-hong
authors.initials: YH
authors.lastname: Luo
mesh_terms: D000972:Antineoplastic Agents, Phytogenic / Q000008:administration & dosage / Q000494:pharmacology*; D017209:Apoptosis / Q000187:drug effects; D002453:Cell Cycle / Q000187:drug effects; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects; D002867:Chromones / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D019008:Drug Resistance, Neoplasm; D066246:ErbB Receptors / Q000037:antagonists & inhibitors / Q000378:metabolism*; D048049:Extracellular Signal-Regulated MAP Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism; D005419:Flavonoids / Q000494:pharmacology; D006801:Humans; D008545:Melanoma / Q000378:metabolism / Q000473:pathology*; D009025:Morpholines / Q000494:pharmacology; D017239:Paclitaxel / Q000008:administration & dosage / Q000494:pharmacology*; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism; D000081082:Phosphoinositide-3 Kinase Inhibitors; D010766:Phosphorylation; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism; D011799:Quinazolines / Q000494:pharmacology; D015398:Signal Transduction / Q000187:drug effects; D020032:Tyrphostins / Q000494:pharmacology
chemical_list: D000972:Antineoplastic Agents, Phytogenic; D002867:Chromones; D066246:ErbB Receptors; D048049:Extracellular Signal-Regulated MAP Kinases; D005419:Flavonoids; D009025:Morpholines; D017239:Paclitaxel; D019869:Phosphatidylinositol 3-Kinases; D000081082:Phosphoinositide-3 Kinase Inhibitors; D051057:Proto-Oncogene Proteins c-akt; D011799:Quinazolines; D020032:Tyrphostins; C101044:RTKI cpd; C085911:2-(4-morpholinyl)-8-phenyl-4H-1-benzopyran-4-one; C093973:2-(2-amino-3-methoxyphenyl)-4H-1-benzopyran-4-one