K(Ca)3.1 Channels and Glioblastoma: In Vitro Studies

Background: Several tumor entities including brain tumors aberrantly overexpress intermediate conductance Ca2+ activated K(Ca)3.1 K+ channels. These channels contribute significantly to the transformed phenotype of the tumor cells. Method: PubMed was searched in order to summarize our current knowledge on the molecular signaling upstream and downstream and the effector functions of K(Ca)3.1 channel activity in tumor cells in general and in glioblastoma cells in particular. In addition, K(Ca)3.1 expression and function for repair of DNA double strand breaks was determined experimentally in primary glioblastoma cultures in dependence on the abundance of proneural and mesenchymal stem cell markers. Results: By modulating membrane potential, cell volume, Ca2+ signals and the respiratory chain, K(Ca)3.1 channels in both, plasma and inner mitochondrial membrane, have been demonstrated to regulate many cellular processes such as migration and tissue invasion, metastasis, cell cycle progression, oxygen consumption and metabolism, DNA damage response and cell death of cancer cells. Moreover, K(Ca)3.1 channels have been shown to crucially contribute to resistance against radiotherapy. Futhermore, the original in vitro data on K(Ca)3.1 channel expression in subtypes of glioblastoma stem(-like) cells propose K(Ca)3.1 as marker for the mesenchymal subgroup of cancer stem cells and suggest that K(Ca)3.1 contributes to the therapy resistance of mesenchymal glioblastoma stem cells. Conclusion: The data suggest K(Ca)3.1 channel targeting in combination with radiotherapy as promising new tool to eradicate therapy-resistant mesenchymal glioblastoma stem cells.