Fez1/lzts1 alterations in gastric carcinoma.
OBJECTIVE
Loss of heterozygosity (LOH) involving the short arm of chromosome 8 (8p) is a common feature of the malignant progression of human tumors, including gastric cancer. We have cloned and mapped a candidate tumor suppressor gene, FEZ1/LZTS1, to 8p22. Here we have analyzed whether FEZ1/LZTS1 alterations play a role in the development and progression of gastric carcinoma.


METHODS
We examined Fez1/Lzts1 expression in 8 gastric carcinoma cell lines by Western blot, and in 88 primary gastric carcinomas by immunohistochemistry. Twenty-six of these 88 primary gastric carcinomas were also microdissected and tested for LOH at the FEZ1/LZTS1 locus and for mutation of the FEZ1/LZTS1 gene. Furthermore, we studied the FEZ1/LZTS1 gene regulation and transcriptional control and the methylation status of the 5' region of the gene in all 8 gastric carcinoma cell lines.


RESULTS
Fez1/Lzts1 protein was barely detectable in all of the gastric cancer cell lines tested and was absent or significantly reduced in 39 of the 88 (44.3%) gastric carcinomas analyzed by immunohistochemistry, with a significant correlation (P < 0.001) to diffuse histotype. DNA allelotyping analysis showed allelic loss in 3 of 17 (18%) and microsatellite instability in 4 of 17 (23.5%) cases informative for D8S261 at the FEZ1/LZTS1 locus. When we compared the presence of LOH with Fez1/Lzts1 expression, we found loss of protein expression in all three of the tumors with allelic imbalance at D8S261. A missense mutation was detected in one case that did not express Fez1/Lzts1. Hypermethylation of the CpG island flanking the Fez1/Lzts1 promoter was evident in six of the eight cell lines examined as well as in the normal control.


CONCLUSIONS
Our findings support FEZ1/LZTS1 as a candidate tumor suppressor gene at 8p in a subtype of gastric cancer and suggest that its inactivation is attributable to several factors including genomic deletion and methylation.
Vecchione
A
A
Kimmel Cancer Center, Jefferson Medical College of Thomas Jefferson University, Philadelphia, Pennsylvania 19107, USA.
Ishii
H
H
Shiao
Y H
YH
Trapasso
F
F
Rugge
M
M
Tamburrino
J F
JF
Murakumo
Y
Y
Alder
H
H
Croce
C M
CM
Baffa
R
R
D048868:Adaptor Proteins, Signal Transducing; D000483:Alleles; D001483:Base Sequence; D015139:Blotting, Southern; D015153:Blotting, Western; D001921:Brain / Q000378:metabolism; D002467:Cell Nucleus / Q000378:metabolism; D002898:Chromosomes, Human, Pair 8; D018899:CpG Islands; D004247:DNA / Q000378:metabolism; D019175:DNA Methylation; D004252:DNA Mutational Analysis; D018076:DNA, Complementary / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000096:biosynthesis* / Q000235:genetics*; D017353:Gene Deletion; D015723:Gene Library; D016147:Genes, Tumor Suppressor; D006801:Humans; D015151:Immunoblotting; D007150:Immunohistochemistry; D019656:Loss of Heterozygosity; D008969:Molecular Sequence Data; D020125:Mutation, Missense; D009419:Nerve Tissue Proteins; D011233:Precipitin Tests; D011401:Promoter Regions, Genetic; D011485:Protein Binding; D011994:Recombinant Proteins / Q000378:metabolism; D013274:Stomach Neoplasms / Q000235:genetics* / Q000378:metabolism*; D014407:Tumor Cells, Cultured; D025521:Tumor Suppressor Proteins
D048868:Adaptor Proteins, Signal Transducing; D018076:DNA, Complementary; D004268:DNA-Binding Proteins; C528597:FEZ1 protein, human; C118711:LZTS1 protein, human; D009419:Nerve Tissue Proteins; D011994:Recombinant Proteins; D025521:Tumor Suppressor Proteins; D004247:DNA