Original Article
Copyright ©2012 Baishideng Publishing Group Co., Limited. All rights reserved.
World J Gastroenterol. Aug 21, 2012; 18(31): 4127-4135
Published online Aug 21, 2012. doi: 10.3748/wjg.v18.i31.4127
siRNA-mediated downregulation of TC21 sensitizes esophageal cancer cells to cisplatin
Md. Raghibul Hasan, Shyam Singh Chauhan, Rinu Sharma, Ranju Ralhan
Md. Raghibul Hasan, Shyam Singh Chauhan, Department of Biochemistry, All India Institute of Medical Sciences, New Delhi 110029, India
Rinu Sharma, Department of Biotechnology, School of Biotechnology, Guru Gobind Singh Indraprastha University, New Delhi 110075, India
Ranju Ralhan, Department of Otolaryngology-Head and Neck Surgery, Joseph and Mildred Sonshine Family Centre for Head and Neck Diseases, Mount Sinai Hospital, Toronto, ON M5G 1X5, Canada
Ranju Ralhan, Department of Pathology and Laboratory Medicine, Alex Simona Shnaider Laboratory for Molecular Oncology, Mount Sinai Hospital, Toronto, ON M5G 1X5, Canada
Author contributions: Hasan MR designed the study and carried out the experimental procedures, and significantly contributed to the analysis of data and manuscript preparation; Chauhan SS contributed to drafting the manuscript; Sharma R conceptualized and designed the study, contributed in the initial standardization of the RNAi experiments and was involved in interpretation of data and drafting the manuscript; Ralhan R was involved in drafting the manuscript, revising it critically for important intellectual content, and has given approval for the final version; all authors approve the final manuscript.
Supported by Department of Science and Technology, Government of India
Correspondence to: Dr. Rinu Sharma, Assistant Professor, School of Biotechnology, Guru Gobind Singh Indraprastha University, Sector 16 C , Dwarka, New Delhi 110075, India. rinusharma@gmail.com
Telephone: +91-11-25302312 Fax: +91-11-25302111
Received: November 24, 2011
Revised: May 7, 2012
Accepted: May 26, 2012
Published online: August 21, 2012

AIM: To determine the functional significance of TC21 in esophageal squamous cell carcinoma (ESCC).

METHODS: TC21 siRNA transfection was carried out using Hyperfectamine to knock down TC21, and transcripts were analyzed by reverse transcription-polymerase chain reaction and protein by Western blotting. We demonstrated the effect of TC21 downregulation of cell signaling in esophageal cancer cells by assessing the phosphorylation status of its downstream targets, phosphoinositide 3-kinase (PI3K), phosphatase and tensin homolog (PTEN), protein kinase B (pAkt), nuclear factor-κB (NF-κB) and cyclinD1 using specific antibodies. Cell survival analysis after cisplatin treatment was carried out by cell viability assay and cell cycle analysis using flow cytometry.

RESULTS: TC21 knockdown in human ESCC cell line TE13 cells, showed only a marginal increase (14.2%) in cell death compared with control cells. The expressions of the signaling proteins PI3K and pAkt, transcription factor NF-κB, and cell cycle protein cyclin D1 were markedly decreased in response to TC21 downregulation, whereas the level of pPTEN, an antagonist of PI3K, was increased. In addition, we evaluated the potential of TC21 as a putative target for sensitizing ESCC cells to the chemotherapeutic agent cisplatin. Increased cell death (38.4%) was observed in cells treated with cisplatin after TC21 knockdown compared with cells which were treated with cisplatin alone (20% cell death).

CONCLUSION: Results suggest that TC21 mediates its effects via the PI3K-Akt pathway, NF-κB and cyclin D1, and enhances chemoresistance in esophageal cancer cells.

Keywords: TC21, Esophageal squamous cell carcinoma, siRNA, Cisplatin, Chemosensitivity