title: Melatonin induces apoptosis through biomolecular changes, in SK-LU-1 human lung adenocarcinoma cells.
abstract: OBJECTIVE
  Anti-cancer effects of melatonin (N-acetyl-5-methoxytryptamine, an indole-amine), have been widely reported, however, little has been known, regarding its mechanism(s) of action in lung cancer. Thus, we investigated its induction of apoptosis through biomolecular changes (lipid, protein and nucleic acid/DNA) in the SK-LU-1 human lung cancer cell line.
  
  
  METHODS
  We used Fourier transform infrared (FTIR) microspectroscopy, and conventional methods, to confirm changes in lipid (annexin V/PI staining for membrane alteration), protein (caspase-3/7 protein activity) and DNA (DAPI staining for DNA fragmentation).
  
  
  RESULTS
  We observed from FTIR data that melatonin increased lipid content and reduced intensity of nucleic acid/DNA, confirmed by annexin V/PI and DAPI respectively. Secondary protein structure at 1656 cm(-1) (α-helix) was reduced and peak position of β-sheet structure (1637 cm(-1) ) was shifted to lower frequency. Alteration in apoptotic proteins was demonstrated via caspase-3/7 activity induction.
  
  
  CONCLUSIONS
  High melatonin concentration exerted anti-cancer effects by changing biomolecular structure of lipids, nucleic acids and proteins, supporting its enhancement of apoptotic induction.
authors.affiliation: Melatonin Research Group, Faculty of Pharmaceutical Sciences, Khon Kaen University, Khon Kaen, 40002, Thailand.
authors.forename: P
authors.initials: P
authors.lastname: Plaimee
authors.forename: N
authors.initials: N
authors.lastname: Weerapreeyakul
authors.forename: K
authors.initials: K
authors.lastname: Thumanu
authors.forename: W
authors.initials: W
authors.lastname: Tanthanuch
authors.forename: S
authors.initials: S
authors.lastname: Barusrux
mesh_terms: D000230:Adenocarcinoma / Q000378:metabolism / Q000473:pathology; D017209:Apoptosis / Q000187:drug effects*; D053148:Caspase 3 / Q000737:chemistry / Q000378:metabolism; D053179:Caspase 7 / Q000737:chemistry / Q000378:metabolism; D045744:Cell Line, Tumor; D053938:DNA Fragmentation / Q000187:drug effects; D006801:Humans; D008175:Lung Neoplasms / Q000378:metabolism / Q000473:pathology; D008550:Melatonin / Q000633:toxicity*; D008563:Membrane Lipids / Q000737:chemistry; D025341:Principal Component Analysis; D017433:Protein Structure, Secondary; D017550:Spectroscopy, Fourier Transform Infrared
chemical_list: D008563:Membrane Lipids; D053148:Caspase 3; D053179:Caspase 7; D008550:Melatonin