Polo-like kinase 1, a new therapeutic target in hepatocellular carcinoma

• Published in: World journal of gastroenterology : WJG 2012-07, Vol.18 (27), p.3527-3536
• Main Authors: Mok, Wei Chuen, Wasser, Shanthi, Tan, Theresa, Lim, Seng Gee
• Format: Article
• Language: English
• Subjects: Adult; Aged; Aged, 80 and over; Amino Acid Chloromethyl Ketones - pharmacology; Animals; Apoptosis; Blotting, Western; Carcinoma, Hepatocellular - enzymology; Carcinoma, Hepatocellular - genetics; Carcinoma, Hepatocellular - pathology; Carcinoma, Hepatocellular - therapy; Caspase 3 - metabolism; Caspase Inhibitors - pharmacology; caspase-3; Cell Cycle Proteins - genetics; Cell Cycle Proteins - metabolism; Cell Proliferation; Endodeoxyribonucleases - metabolism; Female; Fluorescent Antibody Technique; Gene Knockdown Techniques; Genetic Therapy; Hep G2 Cells; Humans; Liver Neoplasms - enzymology; Liver Neoplasms - genetics; Liver Neoplasms - pathology; Liver Neoplasms - therapy; Male; Mice; Mice, Nude; Middle Aged; Original; Polo-Like Kinase 1; Protein Serine-Threonine Kinases - genetics; Protein Serine-Threonine Kinases - metabolism; Proto-Oncogene Proteins - genetics; Proto-Oncogene Proteins - metabolism; Real-Time Polymerase Chain Reaction; Reverse Transcriptase Polymerase Chain Reaction; RNA Interference; RT-PCR; Transfection; Tumor Burden; Western印迹; Xenograft Model Antitumor Assays; 治疗; 激酶; 肝细胞肝癌; 逆转录聚合酶链反应; 靶点
• ISSN: 1007-9327; 2219-2840
• DOI: 10.3748/wjg.v18.i27.3527

AIM： To investigate the role of polo-like kinase 1 （PLK1） as a therapeutic target for hepatocellular carcinoma （HCC）. METHODS： PLK1 gene expression was evaluated in HCC tissue and HCC cell lines. Gene knockdown with short-interfering RNA （siRNA） was used to study PLK1 gene and protein expression using real-time reverse transcription polymerase chain reaction （RT-PCR） and Western blotting, and cell proliferation using 3-（4,5-dim ethylthiazol-2-yl）-5-（3-carboxymethoxyphenyl）-2（4-sulf ophenyl）-2H-tetrazolium （MTS） and bromodeoxyuridine （BrdU） assays. Apoptosis was evaluated using the terminal deoxynucleotidyl transferase dUTP nick end label- ing （TUNEL） assay, and caspase-inhibition assay. Huh-7 cells were transplanted into nude mice and co-cultured with PLK1 siRNA or control siRNA, and tumor progres- sion was compared with controls. RESULTS： RT-PCR showed that PLK1 was overexpre- ssed 12-fold in tumor samples compared with controls, and also was overexpressed in Huh-7 cells, siRNA against PLK1 showed a reduction in PLK1 gene and protein expression of up to 96% in Huh-7 cells, and a reduction in cell proliferation by 68% and 92% in MTS and BrdU cell proliferation assays, respectively. There was a 3-fold increase in apoptosis events, and TUNEL staining and caspase-3 assays suggested that this was caspase-independent. The pan-caspase inhibitor Z-VAD-FMK was unable to rescue the apoptotic cells. Immnofluorescence co-localized endonuclease-G to fragmented chromosomes, implicating it in apoptosis. Huh-7 cells transplanted subcutaneously into nude mice showed tumor regression in siPLKl-treated mice, but not in controls. CONCLUSION： Knockdown of PLK1 overexpression in HCC was shown to be a potential therapeutic target, leading to apoptosis through the endonuclease-G path- way.