MOP-dependent enhancement of methadone on the effectiveness of ALA-PDT for A172 cells by upregulating phosphorylated JNK and BCL2

Photodiagnosis Photodyn Ther. 2020 Jun:30:101657. doi: 10.1016/j.pdpdt.2020.101657. Epub 2020 Jan 13.


Background: Methadone, as a long-acting opioid analgesic, shows an ability to sensitize the treatment of ALA-PDT for glioblastoma cells (A172) in vitro by promoting apoptosis. However, the mechanisms how methadone enhances the effectiveness of ALA-PDT for tumor cells remains to be clarified.

Methods: The expression of mu opioid receptor (MOP), apoptosis, phosphorylated c-Jun N-terminal kinase (JNK) and phosphorylated apoptosis regulator B cell lymphoma 2 (BCL2) were measured by flow cytometry. Cytotoxicity was determined using Cell Counting Kit-8 (CCK-8). A MOP antagonist, naloxone, was used to evaluate the role of MOP in the above process.

Results: It was found that A172 cells show the expression of MOP and that naloxone inhibits the enhancement of the methadone effect on apoptosis following ALA-PDT (p < 0.05). Phosphorylated JNK and BCL2 induced by ALA-PDT were promoted in the presence of methadone (p < 0.05). These methadone effects were also inhibited by naloxone (p < 0.05).

Conclusions: The results suggest that apoptosis induced by ALA-PDT is enhanced by methadone, mostly MOP-mediated, through the upregulation of accumulation of phosphorylated JNK and BCL2, leading to a promotion of cytotoxicity of ALA-PDT for A172 cells.

Keywords: ALA-PDT; Apoptosis; BCL2; Glioblastoma; JNK; MOP; Methadone.

MeSH terms

  • Aminolevulinic Acid* / pharmacology
  • Apoptosis
  • Cell Line, Tumor
  • Humans
  • MAP Kinase Kinase 4
  • Methadone / pharmacology*
  • Phosphorylation
  • Photochemotherapy* / methods
  • Photosensitizing Agents / pharmacology
  • Proto-Oncogene Proteins c-bcl-2
  • Receptors, Opioid, mu
  • Triazenes


  • BCL2 protein, human
  • Photosensitizing Agents
  • Proto-Oncogene Proteins c-bcl-2
  • Receptors, Opioid, mu
  • Triazenes
  • 1-phenyl-3,3-dimethyltriazene
  • Aminolevulinic Acid
  • MAP Kinase Kinase 4
  • Methadone