title: Capsaicin induces cell cycle arrest and apoptosis in human KB cancer cells.
abstract: BACKGROUND
  Capsaicin, a pungent phytochemical in a variety of red peppers of the genus Capsicum, has shown an anti-proliferative effect on various human cancer cell lines. In contrast, capsaicin has also been considered to promote the growth of cancer cells. Thus, the effects of capsaicin on various cell types need to be explored. The anti-proliferative effects of capsaicin on human KB cancer cells are still unknown. Therefore, we examined the viability, cell cycle progression, and factors associated with apoptosis in KB cells treated with capsaicin.
  
  
  METHODS
  The cell proliferation/viability and cytotoxicity of KB cells exposed to capsaicin were determined by a sulforhodamine B colorimetric assay and trypan blue exclusion. Apoptosis was detected by Hoechst staining and confirmed by western blot analysis of poly-(ADP-ribose) polymerase cleavage. Cell cycle distribution and changes of the mitochondrial membrane potential were analyzed by flow cytometry. Furthermore, the expression of caspase 3, 8 and 9 was evaluated by immunoblotting.
  
  
  RESULTS
  We found that treatment of KB cells with capsaicin significantly reduced cell proliferation/viability and induced cell death in a dose-dependent manner compared with that in the untreated control. Cell cycle analysis indicated that exposure of KB cells to capsaicin resulted in cell cycle arrest at G2/M phase. Capsaicin-induced growth inhibition of KB cells appeared to be associated with induction of apoptosis. Moreover, capsaicin induced disruption of the mitochondrial membrane potential as well as activation of caspase 9, 3 and poly-(ADP-ribose) polymerase in KB cells.
  
  
  CONCLUSIONS
  Our data demonstrate that capsaicin modulates cell cycle progression and induces apoptosis in human KB cancer cells through mitochondrial membrane permeabilization and caspase activation. These observations suggest an anti-cancer activity of capsaicin.
authors: Department of Otorhinolaryngology, Head and Neck Surgery, Changhua Christian Hospital, 135 Nanhsiao St, Changhua, Taiwan.
authors: Chia-Han
authors: CH
authors: Lin
authors: Wei-Cheng
authors: WC
authors: Lu
authors: Che-Wei
authors: CW
authors: Wang
authors: Ya-Chi
authors: YC
authors: Chan
authors: Mu-Kuan
authors: MK
authors: Chen
mesh_terms: D000972:Antineoplastic Agents, Phytogenic / Q000494:pharmacology / Q000627:therapeutic use; D017209:Apoptosis / Q000187:drug effects*; D002211:Capsaicin / Q000494:pharmacology / Q000627:therapeutic use*; D002212:Capsicum / Q000737:chemistry*; D053148:Caspase 3 / Q000378:metabolism; D053453:Caspase 9 / Q000378:metabolism; D049109:Cell Proliferation / Q000187:drug effects; D002470:Cell Survival / Q000187:drug effects; D004305:Dose-Response Relationship, Drug; D016195:G2 Phase; D006801:Humans; D007624:KB Cells; D059566:M Phase Cell Cycle Checkpoints / Q000187:drug effects*; D053078:Membrane Potential, Mitochondrial / Q000187:drug effects; D008928:Mitochondria / Q000187:drug effects / Q000502:physiology; D009369:Neoplasms / Q000188:drug therapy* / Q000378:metabolism / Q000503:physiopathology; D008517:Phytotherapy; D010936:Plant Extracts / Q000494:pharmacology / Q000627:therapeutic use*; D011065:Poly(ADP-ribose) Polymerases / Q000378:metabolism
chemical_list: D000972:Antineoplastic Agents, Phytogenic; D010936:Plant Extracts; D011065:Poly(ADP-ribose) Polymerases; D053148:Caspase 3; D053453:Caspase 9; D002211:Capsaicin