Aberrantly hypermethylated Homeobox A2 derepresses metalloproteinase-9 through TBP and promotes invasion in Nasopharyngeal carcinoma.
Nasopharyngeal carcinoma (NPC) is notorious for its high invasiveness and metastatic ability. In this study, we identified a differential hypermethylated transcription repressor, Homeobox A2 (HOXA2), which may render NPC cells invasive and metastatic. Aberrant hypermethylation of HOXA2 led to low RNA expression in NPC tumors and cells. Addition of methylation inhibitor 5'Aza restored HOXA2 RNA expression in NPC cells. Methylated HOXA2 promoter reduces the binding affinity of the transcriptional co-activator p300, causing transcriptional repression of HOXA2. In NPC cells, re-expression of ectopic HOXA2 was correlated with decreased invasive ability and reduced metalloproteinase MMP-9 RNA and protein expression. Promoter, ChIP and DNA-pull down assays indicated that HOXA2 competes with the transcription activator, TATA-box binding protein (TBP) for a recognition sequence near the MMP-9 transcription start site, and suppresses MMP-9 transcription. Thus, HOXA2 acts as a suppressor or TBP-antagonist to inhibit MMP-9 expression; while methylation-mediated inactivation of HOXA2 in NPC derepresses MMP-9 production and increases invasion of NPC cells. In NPC plasma samples, increased plasma EBV copy number was correlated with increased in cell-free HOXA2 hypermethylation and elevated MMP-9 levels. Plasma EBV DNA and methylated cell-free HOXA2 can be used as biomarkers for monitoring NPC treatment.
Graduate Institute of Biomedical Sciences, Chang Gung University, Taoyuan, Taiwan, Republic of China.
Hsin-Pai
HP
Li
Chen-Ching
CC
Peng
I-Che
IC
Chung
Mei-Yuan
MY
Huang
Shao-Tung
ST
Huang
Chia-Chun
CC
Chen
Kai-Ping
KP
Chang
Cheng-Lung
CL
Hsu
Yu-Sun
YS
Chang
D002277:Carcinoma; D048708:Cell Growth Processes / Q000502:physiology; D045744:Cell Line, Tumor; D019175:DNA Methylation; D005801:Genes, Homeobox; D018398:Homeodomain Proteins / Q000235:genetics* / Q000378:metabolism; D006801:Humans; D020780:Matrix Metalloproteinase 9 / Q000235:genetics* / Q000378:metabolism; D000077274:Nasopharyngeal Carcinoma; D009303:Nasopharyngeal Neoplasms / Q000188:drug therapy / Q000235:genetics* / Q000378:metabolism / Q000473:pathology; D009361:Neoplasm Invasiveness; D035181:TATA-Box Binding Protein / Q000235:genetics* / Q000378:metabolism; D015533:Transcriptional Activation
C520321:HOXA2 protein, human; D018398:Homeodomain Proteins; D035181:TATA-Box Binding Protein; C509817:TBP protein, human; D020780:Matrix Metalloproteinase 9