The Study On The Roles Of Kank 1 Gene In The Pathogenesis Of Nasopharyngeal Carcinoma

Background:Nasopharyngeal carcinoma(NPC) is one of the most common malignant tumors in southern China and Southeast Asia,with an incidence rate ranging from 20 to 50/100,000.As an etiologically multi-factorial disease,carcinogenesis of the nasopharynx may result from combined effects of Epstein-Barr viral,genetic and environmental factors.Although numerous efforts have been made to reveal the molecular mechanism of NPC carcinogenesis,it remains poorly understood.Kank 1(kidney ankyrin repeat-containing protein),a potential tumor suppressor gene cloned from renal cell carcinoma,has multiple physiological and pathophysiological functions.But till now the relationship between the Kankl gene and NPC has not been reported.Methods:RT-PCR and real-time RT- PCR technology were used to detect the expression of Kank 1 mRNA in the human NPC cell lines, immorted normal nasopharyngeal epithelial cell line NP69,NPC tissues and the normal nasopharyngeal mucosal tissues.5-8F NPC cells were stably transfected with Kank 1-expressed plasmid pCMV-Kank 1 or empty vector to establish a stably transfected cell lines.And then in vitro transwell migration and invasion assays were used to examine the effect of Kank 1 up-regulation on the migration and invasion of NPC cells,and MTT assay,Hoechst staining,flow cytometry(FCM) analysis and soft-agar colony formation assay were used to examine the effect of Kank 1 up-regulation on the proliferation,cell cycle distribution,cell apoptosis and anchorage-independent growth of NPC cells,respectively.Results:(1) There was significantly down-regulation in the levels of Kankl mRNA in the human NPC cell lines compared to NP69,and in NPC tissues compared to the normal nasopharyngeal mucosal tissues.(2) 5-8F cell line stably transfected with pCMV-Kank 1 was successfully established.(3) Up-regulation of Kank 1 expression in the 5-8F cell line could inhibit the cell proliferation and anchorage-independent growth, cause an increase in the number of G₀/G₁ phase cells,and induce cell apoptosis.(4) Up-regulation of Kank 1 expression in 5-8F cells could obviously decrease the ability of in vitro cell invasion and migration.Conclusion:Kank 1 mRNA was down-regulaed in NPC tissues and NPC cell lines,and up-regulated Kank 1 expression could inhibit the cell invasion,migration,proliferation and anchorage-independent growth of human NPC cell line 5-8F,and induce 5-8F cell apoptosis,which indicate that Kank 1 downregulation may play an important role in the NPC development and progression.