Inhibition of transient receptor potential canonical channels impairs cytokinesis in human malignant gliomas.
OBJECTIVE
Glial-derived primary brain tumours, gliomas, are among the fastest growing malignancies and present a huge clinical challenge. Research suggests an important, yet poorly understood, role of ion channels in growth control of normal and malignant cells. In this study, we sought to functionally characterize Transient Receptor Potential Canoncial (TRPC) channels in glioma cell proliferation. TRPC channels form non-selective cation channels that have been suggested to represent a Ca(2+) influx pathway impacting cellular growth.


METHODS
Employing a combination of molecular, biochemical and biophysical techniques, we characterized TRPC channels in glioma cells.


RESULTS
We showed consistent expression of four channel family members (TRPC-1, -3, -5, -6) in glioma cell lines and acute patient-derived tissues. These channels gave rise to small, non-voltage-dependent cation currents that were blocked by the TRPC inhibitors GdCl(3), 2-APB, or SKF96365. Importantly, TRPC channels contributed to the resting conductance of glioma cells and their acute pharmacological inhibition caused an approximately 10 mV hyperpolarization of the cells' resting potential. Additionally, chronic application of the TRPC inhibitor SKF96365 caused near complete growth arrest. A detailed analysis, by fluorescence-activated cell sorting and time-lapse microscopy, showed that growth inhibition occurred at the G(2)+ M phase of the cell cycle with cytokinesis defects. Cells underwent incomplete cell divisions and became multinucleate, enlarged cells.


CONCLUSIONS
Nuclear atypia and enlarged cells are histopathological hallmarks for glioblastoma multiforme, the highest grade glioma, suggesting that a defect in TRPC channel function may contribute to cellular abnormalities in these tumours.
Bomben
V C
VC
Department of Neurobiology, Center for Glial Biology in Medicine, University of Alabama at Birmingham, AL 35294, USA.
Sontheimer
H W
HW
D001706:Biopsy; D015153:Blotting, Western; D001896:Boron Compounds / Q000494:pharmacology; D001932:Brain Neoplasms / Q000378:metabolism / Q000473:pathology*; D002453:Cell Cycle; D045744:Cell Line, Tumor; D049109:Cell Proliferation; D005910:Glioma / Q000378:metabolism / Q000473:pathology*; D006801:Humans; D007093:Imidazoles / Q000494:pharmacology; D007150:Immunohistochemistry; D050051:Transient Receptor Potential Channels / Q000037:antagonists & inhibitors* / Q000378:metabolism / Q000502:physiology
C504876:2-aminoethoxydiphenylborane; D001896:Boron Compounds; D007093:Imidazoles; D050051:Transient Receptor Potential Channels; C063159:1-(2-(3-(4-methoxyphenyl)propoxy)-4-methoxyphenylethyl)-1H-imidazole