Article
Methadone induced cell death in glioblastoma cells compared to normal astrocytes
Methadon induzierter Zelltod in Glioblastom Zellen verglichen mit normalen Astrozyten
Search Medline for
Authors
Published: | May 8, 2019 |
---|
Outline
Text
Objective: Glioblastoma (GBM) is the most frequent primary brain tumor in the adulthood and carries a dismal prognosis. Recently, D,L-methadone has been put forward as adjuvant treatment in GBM. In order to address bioavailability issues and test for in vivo efficacy, we plan to apply D,L-methadone in an implanted rat GBM model. In preparation of this work, we wanted to analyze three aspects:
- 1.
- The efficacy of D,L-methadone alone and in conjunction with temozolomide (TMZ) in a panel of rat GBM cell lines
- 2.
- The susceptibility of normal rat astrocytes to D,L-methadone in order to establish a potential therapeutic window in tumor cells compared to their non-neoplastic counterpart; and
- 3.
- The expression of µ-opiod receptor as the target of D,L-methadone in all tested cell lines.
Methods: We utilized three different established rat GBM cell lines (9L, F98, S635) suitable for in vivo modelling. Normal rat astrocytes were obtained as a primary culture from Fisher 344 rats harvested on day three postnatally. The μ-opioid receptor expression was tested by Western blot and immunofluorescence staining. Cells were exposed to 5 concentrations of D,L-methadone (0.3, 1.0, 15, 30, 45 µg/ml) with or without TMZ (100 µM). Cell viability was tested by crystal violet assay.
Results: Expression of the μ-opioid receptor was similar in the tested cell lines; in particular, there was no difference between the GBM cells compared to normal astrocytes. All GBM lines displayed reduced cell viability upon treatment with D,L-methadone starting at 15 µg/ml, however the astrocytes were entirely refractory. Regarding to the interaction with TMZ 100 µM, low concentrations of D,L-methadone were antagonistic in 9L (0.3 & 1 µg/ml) and F98 (1 µg/ml), whereas higher concentrations (15–45 µg/ml) were synergistic in 9L und S635. In contrast, the astrocytes did not react significantly neither to TMZ nor to TMZ combined with D,L-methadone at any concentration.
Conclusion: Although the target expression is comparable, we found a significantly higher susceptibility to D,L-methadone in GBM cells compared to normal astrocytes. However, the tumor cell killing started at concentrations which will not be reached in patients with GBM. At clinically achievable concentrations, D,L-methadone was antagonistic to TMZ in two GBM lines suggesting caution regarding its premature use in the management of GBM patients