Glioblastoma (GBM) is the most malignant brain tumour with poor prognosis and limited therapy effectiveness. Tumour hypoxia is considered as a main reason of GBM’s resistance to medical treatment. It seems that improvement of therapeutic response can be achieved by the combination of chemotherapeutics application with refinement of oxygenation status of tumour tissue. One of the novel anti-tumour compounds is isothiourea derivative ZKK-3, which inhibits the activity of protein kinase D1 (PKD1). PKD1 promotes tumour growth and mediates detoxification of mitochondrial reactive oxygen species (ROS). The aim of this study was to examine the impact of hyperbaric oxygenation (HBO) on the expression of PKD1 protein as well as its phosphorylated forms - pPKD1 (Ser 916) and pPKD1 (Ser 744/748) in glioma cells treated with ZKK-3 in vitro.
Human glioblastoma T98G cell line was cultured in medium supplemented with ZKK-3 and exposed to the various oxygen conditions: normoxia, hypoxia, HBO, double hypoxia, hypoxia/HBO. After 24 hours of incubation cell lysis was made. The level of tested proteins in obtained lysates was examined using Western Blot technique.
Increasing concentration of ZKK-3 caused diminution of PKD1, pPKD1 (Ser 916) and pPKD1 (Ser 744/748) levels in all tested oxygen conditions. Comparison of hypoxia and HBO conditions showed that hyperbaric oxygen administration resulted in enhancement of expressions of all PKD1 forms. Moreover, in groups preincubated in hypoxia conditions the levels of tested proteins were also markedly elevated after hyperbaric oxygenation (hypoxia/HBO) in comparison to the double hypoxia groups.
Increase of PKD1 protein expression as well as its phosphorylated forms evidenced that HBO application resulted in enhancement of oxidative stress in T98G cell line in vitro. This combined with ZKK-3 ability to inhibit activities of those kinases gives ground to consider ZKK-3/HBO therapy as a promising therapeutic strategy for patients with malignant gliomas. Acknowledgement: The research was supported by KNOW-MMRC project and Foundation for the Development of Diagnostic and Therapy.
Clinical trial identification
Legal entity responsible for the study
Mossakowski Medical Research Centre Polish Academy of Sciences
The research was supported by KNOW-MMRC project and Foundation for the Development of Diagnostic and Therapy.
All authors have declared no conflicts of interest.