Methylation of annexin A1 Gene Promotes Lymphoid Node Metastasis in Nasopharyngeal Carcinoma

Abstract: Objective To study the effect of rotary magnetic field (RMF) combining 5-Fu on the cycle and apoptosis of mouse cell line SP2/0 in vitro. Methods SP2/0 cells were randomly divided into four groups: control group (N), 5-Fu group (C), magnetic group (M) and magnetic combining 5-Fu group (M+C).The M and M+C groups were treated with a RMF for two hours once a day.On day 4, the C and M+C groups were treated with 5-Fu 20 μg/ml.On day 5, cell cycle and apoptosis were measured by the flow cytometric (FCM). Results The S phase proportion of the M group and the G1 phase proportion of the C group were higher than that of the other three groups（P<0.05）.The S phase proportion of the M+C group decreased and lower than that of the M group，but was still higher than that of the N and C groups（P<0.05）.There was no significant difference in apoptosis rates between the N and M groups（P>0.05）.The apoptosis rates of the C and M+C groups were remarkedly higher than those of the N and M groups and the M+C group had the highest apoptosis rate. Conclusion The RMF can't induce the apoptosis.But it can enhance the cytotoxicity of 5-Fu and promote the cell apoptosis.The mechanism of the apoptosis may be related to SP2/0 cell line arrested at S phase.Objective To explore the methylation status of annexin A1 gene in nasopharyngeal carcinoma (NPC) tissues and the role of annexin A1 methylation in NPC. Methods Biopsy specimens were harvested from 75 primary NPC tissues and 25 chronic nasopharyngitis nasopharyngeal mucosal tissues.Then, methylation specific PCR (MSP) was conducted to determine methylation status of annexin A1, and semi-quantitative reverse transcription PCR (RT-PCR) was performed to quantify the expression of annexin A1, parallelly, immunohistochemical staining was carried out to assess the ANNEXIN A1 protein levels.Finally, correlation analysis was developed between methylation status, protein expression and the gender, age, NPC staging. Results annexin A1 methylation status in NPC tissues were 7 exhaustive methylation, 62 partial methylation and 6 unmethylation, whereas they were 3 partial methylation and 22 unmethylation in chronic nasopharyngitis nasopharyngeal mucosal tissues.The frequency of annexin A1 methylation in NPC tissues was significant higher than in chronic nasopharyngitis nasopharyngeal mucosal tissues (92% vs. 12%, χ2=60; P<0.05).The results of semi-quantitive RT-PCR and immunohistochemical staining demonstrated that annexin A1 exhaustive methylation leads to absent annexin A1 mRNA and ANNEXIN A1 expression in both NPC tissues and normal nasopharyngeal mucosal tissues.Tissues characterized with partial methylation annexin A1 represented remarkable decreased annexin A1 mRNA and ANNEXIN A1 expression when compared with tissues characterized with unmethylation annexin A1.Correlation analysis indicated that both annexin A1 hypermethylation status and ANNEXIN A1 expression intensity was correlated with NPC lymphoid node metastasis but not with gender, age, prime tumour staging and clinical staging. Conclusion Annexin A1 was frequently methylated in NPC tissues.Methylation leads to the decreased or depleted expression of ANNEXIN A1, and promotes NPC lymphoid node metastasis.