Berberine enhances inhibition of glioma tumor cell migration and invasiveness mediated by arsenic trioxide.
BACKGROUND
Arsenic trioxide (As2O3) exhibits promising anticarcinogenic activity in acute promyelocytic leukemic patients and induces apoptosis in various tumor cells in vitro. Here, we investigated the effect of the natural alkaloid berberine on As2O3-mediated inhibition of cancer cell migration using rat and human glioma cell lines.


METHODS
The 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) assay was used to determine the viability of rat C6 and human U-87 glioma cells after treatment with As2O3 or berberine, and after co-treatment with As2O3 and berberine. The wound scratch and Boyden chamber assays were applied to determine the effect of As2O3 and berberine on the migration capacity and invasiveness of glioma cancer cells. Zymography and Western blot analyses provided information on the effect of As2O3 and berberine on the intracellular translocation and activation of protein kinase C (PKC), and some PKC-related downstream factors. Most assays were performed three times, independently, and data were analyzed using ANOVA.


RESULTS
The cell viability studies demonstrated that berberine enhances As2O3-mediated inhibition of glioma cell growth after 24 h incubation. Untreated control cells formed a confluent layer, the formation of which was inhibited upon incubation with 5 microM As2O3. The latter effect was even more pronounced in the presence of 10 microM berberine. The As2O3-mediated reduction in motility and invasion of glioma cells was enhanced upon co-treatment with berberine. Furthermore, it has been reported that PKC isoforms influence the morphology of the actin cytoskeleton, as well as the activation of metalloproteases MT1-MMP and MMP-2, reported to be involved in cancer cell migration. Treatment of glioma cells with As2O3 and berberine significantly decreased the activation of PKC alpha and epsilon and led to actin cytoskeleton rearrangements. The levels of two downstream transcription factors, myc and jun, and MT1-MMP and MMP-2 were also significantly reduced.


CONCLUSIONS
Upon co-treatment of glioma cells with As2O3 and berberine, cancer cell metastasis can be significantly inhibited, most likely by blocking the PKC-mediated signaling pathway involved in cancer cell migration. This study is potentially interesting for the development of novel chemotherapeutic approaches in the treatment of malignant gliomas and cancer development in general.
Lin
Tseng-Hsi
TH
1Institute of Biochemistry and Biotechnology, Chung Shan Medical University, Taichung 402, Taiwan. jth.lin@gmail.com
Kuo
Hsing-Chun
HC
Chou
Fen-Pi
FP
Lu
Fung-Jou
FJ
D000199:Actins / Q000187:drug effects; D000818:Animals; D000970:Antineoplastic Agents / Q000494:pharmacology*; D000077237:Arsenic Trioxide; D001152:Arsenicals / Q000494:pharmacology*; D001599:Berberine / Q000494:pharmacology*; D045744:Cell Line, Tumor; D002465:Cell Movement / Q000187:drug effects; D049109:Cell Proliferation / Q000187:drug effects; D004789:Enzyme Activation / Q000187:drug effects; D005910:Glioma / Q000188:drug therapy* / Q000473:pathology* / Q000556:secondary; D006801:Humans; D007527:Isoenzymes / Q000378:metabolism; D020778:Matrix Metalloproteinase 2 / Q000378:metabolism; D020780:Matrix Metalloproteinase 9 / Q000378:metabolism; D009361:Neoplasm Invasiveness / Q000517:prevention & control*; D010087:Oxides / Q000494:pharmacology*; D051571:Protein Kinase C-alpha / Q000235:genetics / Q000378:metabolism; D051744:Protein Kinase C-epsilon / Q000235:genetics / Q000378:metabolism; D051381:Rats; D014157:Transcription Factors / Q000187:drug effects* / Q000378:metabolism; D014178:Translocation, Genetic / Q000187:drug effects
D000199:Actins; D000970:Antineoplastic Agents; D001152:Arsenicals; D007527:Isoenzymes; D010087:Oxides; D014157:Transcription Factors; D001599:Berberine; D051571:Protein Kinase C-alpha; D051744:Protein Kinase C-epsilon; C522361:MMP2 protein, human; D020778:Matrix Metalloproteinase 2; D020780:Matrix Metalloproteinase 9; D000077237:Arsenic Trioxide