Objective    To study gene expression involved in hedgehog signaling pathway in human esophageal cancer cell lines

and to investigate the relationship between human hedgehog interacting protein (HHIP) expression and CpG island methylation of HHIP gene promoter.     Methods    In esophageal squamous cell carcinoma cell lines Kyse450

Kyse510 and Yes2 and esophageal adenocarcinoma cell lines Skgt4 and Te7

the expression of hedgehog pathway components SHH

PTCH1

SMO

HHIP and Gli was studied

via

RT-PCR. HHIP gene promoter methylation in esophageal cancer cell lines w

as analyzed through digestion with methylation-sensitive restriction enzyme

Hha

Ⅰ and methylation-dependent restriction enzyme McrBC as well as real-time PCR. The esophageal cancer cell lines were treated with 5-aza-2′-deoxycitydine (5-Aza-CdR)

and the changes of HHIP mRNA expression before and after 5-Aza-CdR treatment were tested.     Results     SHH

PTCH1

SMO and Gli had relatively high mRNA expression levels in all of the five cell lines

while HHIP only showed higher mRNA expression in Kyse450 cell line

with 3-5 times that in the other 4 cell lines. The CpG islands of HHIP gene were in an unmethylated state in Kyse450 cell line

but in a highly methylated state in the other 4 cell lines. In Yes2 cell line that had highly methylated CpG islands

HHIP gene expression level was increased by 10-20 times after 5-Aza-CdR demethylation.     Conclusion      Abnormal activation of hedgehog signaling pathway may be involved in carcinogenesis and development of esophageal cancer. The inhibition of HHIP gene expression is correlated to the high methylation level of the CpG islands in its gene promoter.