CD44 is a potential target of amplification within the 11p13 amplicon detected in gastric cancer cell lines

Abstract

Classical cytogenetic approaches have revealed many of the chromosomal aberrations that may occur in gastric cancers (GC), although few alterations of specific genes have been identified so far. Genes that affect progression of this disease need to be identified if clinicians are to achieve optimal management of patients with GC. As the first step toward the cloning of gene(s) that may be involved in gastric carcinogenesis, we examined 25 GC cell lines for aberrations in DNA copy number to detect chromosomal gains and losses, as well as gene amplifications, by comparative genomic hybridization (CGH). Our CGH study revealed high‐level amplifications in chromosomal regions that had been well defined in GC but also in sites that had not, including 3p24, 5p15, 11p11.2–14, 13q34, 15q26, Xp24, and Xq26–28. The minimal common region at 11p13, within the 11p11.2–14 amplicon, harbors the CD44 gene. Northern and Western blot analyses showed that an alternatively spliced form of CD44, with variant exons 8–10 (CD44E), was overexpressed in all cell lines bearing the 11p13 amplicon. However, cell adhesion activity was no greater in these lines than in cell lines without amplifications at the CD44 locus, suggesting that the major property of upregulated CD44 in these cases might be to transduce signals critically associated with growth and proliferation of the tumor cells. © 2000 Wiley‐Liss, Inc.

IQGAP1, a negative regulator of cell-cell adhesion, is upregulated by gene amplification at 15q26 in gastric cancer cell lines HSC39 and 40A

“…To identify target genes in this amplicon, we first screened ESTs localized to 15q25-26, using Southern blot analysis, in 25 GC cell lines (Fukuda et al 2000). Among them, GEN-326C09 and GEN-154A06 showed amplifications in two cell lines, HSC39 and HSC40A (Fig.…”

“…All of the 25 GC cell lines previously analyzed by CGH (Fukuda et al 2000) were maintained in RPMI 1640 medium supplemented with 10% fetal calf serum (FCS) and penicillin-streptomycin. Of the cell lines, HSC39 and 40A were a gift from Dr. K. Yanagihara.…”

“…The beads were then washed with buffer A, and the bound proteins were coeluted with GST fusion proteins by the addition of buffer A containing 10 mM reduced glutathione. The eluates were subjected to (Fukuda et al 2000). Note that amplification and overexpression of IQGAP1 were observed in these two cell lines (A, B, C).…”

“…Recently, we identified novel amplifications in different chromosomes by comparative genomic hybridization (CGH) in 25 GC cell lines (Fukuda et al 2000). Among these, a novel amplicon at 15q26 was detected in two cell lines, HSC39 and 40A, established from a patient with signet-ring cell carcinoma, using different methods (Yanagihara et al 1991).…”

ADAM23, a possible tumor suppressor gene, is frequently silenced in gastric cancers by homozygous deletion or aberrant promoter hypermethylation

“…The results of the new CGH-array analysis were mostly in accord with our previous CGH/CGH-array data (Fukuda et al, 2000;Takada et al, 2005) and with other published CGH/CGH-array data derived from analysis of primary gastric tumors (Sakakura et al, 1999;Tay et al, 2003;Kimura et al, 2004;Weiss et al, 2004;Gorringe et al, 2005). That is, loci that were frequently detected as high-level amplifications in our study contained the same genes whose amplifications had been known to play important roles in pathogenesis of GC as putative oncogenes, such as MYC, PVT1, KSAM, MET, and KRAS (Tahara, 1995;Koo et al, 2000;Peng et al, 2003).…”