Clinical Trials Study
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World J Gastroenterol. Jul 7, 2014; 20(25): 8229-8236
Published online Jul 7, 2014. doi: 10.3748/wjg.v20.i25.8229
Inhibition of Girdin enhances chemosensitivity of colorectal cancer cells to oxaliplatin
Ya-Jie Zhang, A-Jian Li, Yi Han, Lu Yin, Mou-Bin Lin
Ya-Jie Zhang, A-Jian Li, Yi Han, Lu Yin, Mou-Bin Lin, Department of General Surgery, RuiJin Hospital Affiliated Shanghai Jiaotong University School of Medicine, Shanghai 200025, China
Author contributions: Zhang YJ designed the research; Zhang YJ, Li AJ, Han Y and Lin MB performed the research and analyzed the data; Zhang YJ wrote the paper.
Supported by National Natural Science Foundation of China, No. 81272480/H1609
Correspondence to: Mou-Bin Lin, PhD, Department of General Surgery, RuiJin Hospital Affiliated Shanghai Jiaotong University School of Medicine, No. 197, Ruijin No. 2 Road, Shanghai 200025, China. lmbin@hotmail.com
Telephone: +86-21-64370045 Fax: +86-21-64333548
Received: September 16, 2013
Revised: March 9, 2014
Accepted: April 15, 2014
Published online: July 7, 2014
Abstract

AIM: To investigate the effect of Girdin knockdown on the chemosensitivity of colorectal cancer cells to oxaliplatin and the possible mechanisms involved.

METHODS: Four siRNAs targeting Girdin were transfected into the chemoresistant colorectal cancer cell line DLD1. Real-time polymerase chain reaction (PCR) was employed to assess Girdin mRNA expression and the most effective siRNA was chosen for conversion into shRNA. Then, DLD1 cells were infected with lentiviruses expressing the Girdin shRNA and a scramble control, respectively, and Girdin mRNA and protein expression levels were assessed by real-time PCR and Western blotting. Furthermore, microarray experiments were used to assess global gene expression profile after Girdin suppression in DLD1 cells. Finally, the cytotoxic effect of simultaneous treatment with oxaliplatin and adriamycin (an inhibitor of a significantly downregulated gene after Girdin suppression in DLD1 cells) was examined by MTT assay.

RESULTS: The most effective siRNA suppressed Girdin expression with an inhibition efficiency of 57%. Compared with the scramble control, DLD1 cells infected with the Girdin shRNA displayed decreased Girdin mRNA and protein levels (P < 0.05), and Girdin knockdown significantly enhanced chemosensitivity to oxaliplatin in colorectal cancer cells (P < 0.05). Microarray data revealed that 381 and 162 genes were upregulated and downregulated in response to Girdin reduction, respectively, with ratios > 1.2 or < 0.8 (P < 0.01). Interestingly, TOP2B (DNA topoisomerase 2-β) was downregulated (ratio = 0.78, P = 0.0001) and oxaliplatin/adriamycin combination resulted in increased cell death compared with treatments with individual agents (P < 0.05).

CONCLUSION: Girdin knockdown enhances chemosensitivity of colorectal cancer cells to oxaliplatin via TOP2B down-regulation. These findings provide a promising approach to overcome the chemoresistance of colorectal cancer cells.

Keywords: Oxaliplatin, Chemosensitivity, Girdin, Colorectal cancer, TOP2B

Core tip: The chemoresistance to oxaliplatin is a major problem in the treatment of colorectal cancer (CRC). In this study, a lentivirus-mediated shRNA was constructed to investigate the role of Girdin, a potential regulator of chemotherapy sensitivity. We found that Girdin knockdown enhanced chemosensitivity of colorectal cells to oxaliplatin via reduction of TOP2B. This suggested that Girdin is a modulator of CRC chemoresistance and a potential therapeutic target.