VILIP-1 downregulation in non-small cell lung carcinomas: mechanisms and prediction of survival.
VILIP-1, a member of the neuronal Ca++ sensor protein family, acts as a tumor suppressor gene in an experimental animal model by inhibiting cell proliferation, adhesion and invasiveness of squamous cell carcinoma cells. Western Blot analysis of human tumor cells showed that VILIP-1 expression was undetectable in several types of human tumor cells, including 11 out of 12 non-small cell lung carcinoma (NSCLC) cell lines. The down-regulation of VILIP-1 was due to loss of VILIP-1 mRNA transcripts. Rearrangements, large gene deletions or mutations were not found. Hypermethylation of the VILIP-1 promoter played an important role in gene silencing. In most VILIP-1-silent cells the VILIP-1 promoter was methylated. In vitro methylation of the VILIP-1 promoter reduced its activity in a promoter-reporter assay. Transcriptional activity of endogenous VILIP-1 promoter was recovered by treatment with 5'-aza-2'-deoxycytidine (5'-Aza-dC). Trichostatin A (TSA), a histone deacetylase inhibitor, potently induced VILIP-1 expression, indicating that histone deacetylation is an additional mechanism of VILIP-1 silencing. TSA increased histone H3 and H4 acetylation in the region of the VILIP-1 promoter. Furthermore, statistical analysis of expression and promoter methylation (n = 150 primary NSCLC samples) showed a significant relationship between promoter methylation and protein expression downregulation as well as between survival and decreased or absent VILIP-1 expression in lung cancer tissues (p<0.0001). VILIP-1 expression is silenced by promoter hypermethylation and histone deacetylation in aggressive NSCLC cell lines and primary tumors and its clinical evaluation could have a role as a predictor of short-term survival in lung cancer patients.
Fu
Jian
J
Department of Pathology, Fox Chase Cancer Center, Philadelphia, Pennsylvania, USA.
Fong
Kathryn
K
Bellacosa
Alfonso
A
Ross
Eric
E
Apostolou
Sinoula
S
Bassi
Daniel E
DE
Jin
Fang
F
Zhang
Jirong
J
Cairns
Paul
P
Ibañez de Caceres
Inmaculada
I
Braunewell
Karl-Heinz
KH
Klein-Szanto
Andres J
AJ
D002289:Carcinoma, Non-Small-Cell Lung / Q000175:diagnosis / Q000235:genetics* / Q000401:mortality; D019175:DNA Methylation; D015536:Down-Regulation / Q000235:genetics*; D015972:Gene Expression Regulation, Neoplastic; D020868:Gene Silencing; D006657:Histones / Q000378:metabolism; D006801:Humans; D051596:Neurocalcin / Q000235:genetics*; D011401:Promoter Regions, Genetic; D012333:RNA, Messenger / Q000235:genetics; D015996:Survival Rate
D006657:Histones; D051596:Neurocalcin; D012333:RNA, Messenger; C496688:VSNL1 protein, human