title: Melatonin sensitizes H1975 non-small-cell lung cancer cells harboring a T790M-targeted epidermal growth factor receptor mutation to the tyrosine kinase inhibitor gefitinib.
abstract: OBJECTIVE
  The use of tyrosine kinase inhibitors (TKIs) to target active epidermal growth factor receptor (EGFR)-harbouring mutations has been effective in patients with advanced non-small-cell lung cancer (NSCLC). However, the use of TKIs in NSCLS patients with somatic EGFR mutations, particularly T790M, causes drug resistance. Thus, in the present study, we investigated overcoming resistance against the TKI gefitinib by combination treatment with melatonin in H1975 NSCLC cells harbouring the T790M somatic mutation.
  
  
  METHODS
  H1975 and HCC827 cells were treated with melatonin in combination with gefitinib, and cell viability, cell cycle progression, apoptosis, and EGFR, AKT, p38, Bcl-2, Bcl-xL, caspase 3 and Bad protein levels were examined.
  
  
  RESULTS
  Treatment with melatonin dose-dependently decreased the viability of H1975 cells harbouring the T790M somatic mutation compared to HCC827 cells with an EGFR active mutation. Melatonin-mediated cell death resulted in decreased phosphorylation of EGFR and Akt, leading to attenuated expression of survival proteins, such as Bcl-2, Bcl-xL and survivin, and activated caspase 3 in H1975 cells, but not in HCC827 cells. However, we did not observe a significant change in expression of cell cycle proteins, such as cyclin D, cyclin A, p21 and CDK4 in H1975 cells. Surprisingly, co-treatment of gefitinib with melatonin effectively decreased the viability of H1975 cells, but not HCC827 cells. Moreover, co-treatment of H1975 cells caused consistent down-regulation of EGFR phosphorylation and induced apoptosis compared to treatment with gefitinib or melatonin alone.
  
  
  CONCLUSIONS
  Our findings demonstrate that melatonin acts as a potent chemotherapeutic agent by sensitising to gefitinib TKI-resistant H1975 cells that harbour a EGFR T790M mutation.
authors.affiliation: College of Korean Medicine, Kyung Hee University, Seoul, South Korea.
authors.forename: Miyong
authors.initials: M
authors.lastname: Yun
authors.forename: Eun-Ok
authors.initials: EO
authors.lastname: Kim
authors.forename: Duckgue
authors.initials: D
authors.lastname: Lee
authors.forename: Ji-Hyun
authors.initials: JH
authors.lastname: Kim
authors.forename: Jaekwang
authors.initials: J
authors.lastname: Kim
authors.forename: Hyemin
authors.initials: H
authors.lastname: Lee
authors.forename: Jihyun
authors.initials: J
authors.lastname: Lee
authors.forename: Sung-Hoon
authors.initials: SH
authors.lastname: Kim
mesh_terms: D002289:Carcinoma, Non-Small-Cell Lung / Q000188:drug therapy / Q000235:genetics / Q000473:pathology*; D002455:Cell Division / Q000187:drug effects; D045744:Cell Line, Tumor; D066246:ErbB Receptors / Q000235:genetics* / Q000378:metabolism; D005434:Flow Cytometry; D000077156:Gefitinib; D006801:Humans; D008175:Lung Neoplasms / Q000188:drug therapy / Q000235:genetics / Q000473:pathology*; D008550:Melatonin / Q000494:pharmacology*; D009154:Mutation; D010766:Phosphorylation; D011799:Quinazolines / Q000627:therapeutic use*
chemical_list: D011799:Quinazolines; D066246:ErbB Receptors; D008550:Melatonin; D000077156:Gefitinib