Epigenetic silencing of Aristaless-like homeobox-4, a potential tumor suppressor gene associated with lung cancer

Wen-Bin Liu, Fei Han, Xing-Hua Du, Xiao Jiang, Yong-Hong Li, Yong Liu, Hong-Qiang Chen, Lin Ao, Zhi-Hong Cui, Jia Cao, Jin-Yi Liu
International Journal of Cancer. Journal International du Cancer 2014 March 15, 134 (6): 1311-22
Using genome-wide methylation screening, we found Aristaless-like homeobox-4 (ALX4) preferentially methylated in lung cancer. ALX4 is a putative transcription factor that belongs to the family of paired-class homeoproteins involved in epithelial development. However, the role of ALX4 in tumorigenesis remains largely unclear. Here, we analyzed its epigenetic regulation, biological functions and related molecular mechanisms in lung cancer. CpG island methylation and expression of ALX4 were evaluated by methylation-specific polymerase chain reaction (PCR), bisulfite genomic sequencing, reverse-transcription PCR and Western blotting. ALX4 functions were determined by cell viability, colony formation, flow cytometry and in vivo tumorigenicity assays. ALX4 hypermethylation was detected in 55% (54/98) of primary lung cancers compared to none (0/20) of the normal lung tissue samples tested (p < 0.01). ALX4 was readily expressed in normal lung tissues with an unmethylated status, but downregulated or silenced in 90% (9/10) of lung cancer cell lines with a hypermethylation status. Demethylation experiments further confirmed that loss of ALX4 expression was regulated by CpG island hypermethylation. Re-expression of ALX4 in lung cancer cell lines suppressed cell viability, colony formation and migration, whereas it induced apoptosis and G1/S arrest and restrained the tumorigenicity in nude mice. These effects were associated with upregulation of proapoptotic proteins caspase-7, -8 and -9, and downregulation of Bcl-2. On the other hand, knockdown of ALX4 expression by siRNA increased cell viability and proliferation, whereas it inhibited apoptosis and cell cycle arrest. In conclusion, our results suggest that ALX4 is a novel putative tumor suppressor with epigenetic silencing in lung carcinogenesis.

Full Text Links

Find Full Text Links for this Article


You are not logged in. Sign Up or Log In to join the discussion.

Related Papers

Remove bar
Read by QxMD icon Read

Save your favorite articles in one place with a free QxMD account.


Search Tips

Use Boolean operators: AND/OR

diabetic AND foot
diabetes OR diabetic

Exclude a word using the 'minus' sign

Virchow -triad

Use Parentheses

water AND (cup OR glass)

Add an asterisk (*) at end of a word to include word stems

Neuro* will search for Neurology, Neuroscientist, Neurological, and so on

Use quotes to search for an exact phrase

"primary prevention of cancer"
(heart or cardiac or cardio*) AND arrest -"American Heart Association"