Huaying Liu1,†,
Ming Zhou1,*,
Heran Wang1,
Yukun Liu1,
Xiayu Li3,
Wei Xiong1,
Jian Ma1,
Xiaoling Li1 and
Guiyuan Li1,*
2Henan Medical College, Zhengzhou 451191, China
3The Third Xiang-Ya Hospital, Central South University, Changsha 410013, China
Abstract The proto-oncogene c-Myc encodes a transcription factor that is involved in the regulation of cellular proliferation, differentiation, and apoptosis. Several studies indicate that the over-expression of c-Myc is a frequent genetic abnormality in nasopharyngeal carcinoma (NPC). Therefore, specifically reducing its level by genetic means in established NPC cell lines helps to better understand its role in the pathogenesis of NPC. In this study, for the first time, we successfully established and characterized NPC 5-8F cell line with stably suppressed c-Myc expression by employing a DNA-based RNA interference approach. The suppression of c-Myc resulted in reduced cell growth, colony formation, and cell cycle progression in 5-8F cells. In vivo tumor formation assays revealed that the knockdown of c-Myc reduced the tumorigenic potential of 5-8F cells in nude mice. At the molecular level, we found that the knockdown of c-Myc could decrease the expression of several critical molecules involved in the Cdk/Rb/E2F pathway, including CDK4, cyclin D1, CDK2, pRb, E2F3, and DP2, and significantly reduced the promoter activity of cyclin D1. Taken together, these findings provide valuable mechanistic insights into the role of c-Myc in nasopharyngeal carcinogenesis and suggest that the knockdown of c-Myc may be a potential therapeutic approach for the treatment of NPC.
Keywords nasopharyngeal carcinoma; c-Myc; 5-8F; cell growth; Cdk/Rb/E2F pathway
Received 2014-9-23
Accepted 2014-12-17
Funding This work was supported by the grants from the National Natural Science Foundation of China (Nos. 30772481, 81071686, 81171934, and 81328019) and the Project Sponsored by the Scientific Research Foundation for the Returned Overseas Chinese Scholars, State
* Correspondence address Tel: +86-731-84805412; Fax: +86-731-84805383; E-mail: [email protected] (M.Z.)/ Tel/Fax: +86-731-84805383; E-mail: [email protected] (G.L.)