Invasion of human glioma cells is regulated by multiple chloride channels including ClC-3.
BACKGROUND
Glioblastoma is a type of highly malignant primary brain tumour. By means of ion excretion and the associated obligatory water loss, glioma cells can change shapes and undergo extensive migration and invasion. This study investigated the effects of inhibition of ion excretion in glioma cells.


METHODS
The expression of chloride channels (ClCs) and metalloproteinase-2 (MMP-2) was studied in two human glioma cell lines (STTG1 and U251-MG). The effects of ClC inhibition with chlorotoxin (a ClC-3 inhibitor), 5-nitro-2-3-phenylpropylamino benzoic acid (NPPB) (a non-specific ClC inhibitor), and ClC-3 siRNA knockdown were studied.


RESULTS
Both STTG1 and U251-MG cells expressed ClC family members ClC-2, -3, -4, -5, -6 and -7, as well as MMP-2. Glioma cell invasion was markedly but not completely inhibited by ClC-3 and MMP-2 siRNA knockdown, and by chlorotoxin treatment. Addition of chlorotoxin to siRNA-treated glioma cells only slightly increased the suppression of invasion. In contrast, invasion was completely blocked by the non-specific ClC blocker NPPB.


CONCLUSIONS
ClCs are crucial in glioma cell migration and invasion. Blockade of a single ClC, however, is not sufficient to achieve complete inhibition of glioma cell invasion, suggesting that any future therapy should be targeted at pharmacological blockade of multiple ClCs.
Department of Surgery, LKS Faculty of Medicine, The University of Hong Kong, Pokfulam, Hong Kong, PR China.
Vincent Chi Hang
VC
Lui
Steven Sin Sai
SS
Lung
Jenny Kan Suen
JK
Pu
Kwan Ngai
KN
Hung
Gilberto Kat Kit
GK
Leung
D015153:Blotting, Western; D001932:Brain Neoplasms / Q000235:genetics / Q000473:pathology*; D002448:Cell Adhesion / Q000187:drug effects; D002465:Cell Movement / Q000187:drug effects*; D049109:Cell Proliferation / Q000187:drug effects; D018118:Chloride Channels / Q000502:physiology*; D005455:Fluorescent Antibody Technique; D020868:Gene Silencing / Q000502:physiology; D005910:Glioma / Q000235:genetics / Q000473:pathology*; D006801:Humans; D007124:Immunoenzyme Techniques; D020778:Matrix Metalloproteinase 2 / Q000502:physiology*; D009361:Neoplasm Invasiveness; D009498:Neurotoxins / Q000494:pharmacology; D012333:RNA, Messenger / Q000235:genetics; D034741:RNA, Small Interfering / Q000235:genetics; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012604:Scorpion Venoms / Q000494:pharmacology; D014407:Tumor Cells, Cultured
D018118:Chloride Channels; C115376:ClC-3 channel; D009498:Neurotoxins; D012333:RNA, Messenger; D034741:RNA, Small Interfering; D012604:Scorpion Venoms; C091539:Chlorotoxin; D020778:Matrix Metalloproteinase 2