A consistent pattern ofRIN1 rearrangements in oral squamous cell carcinoma cell lines supports a breakage-fusion-bridge cycle model for 11q13 amplification

Abstract

Gene amplification is a common feature of tumors. Overexpression of some amplified genes plays a role in tumor progression. Gene amplification can occur either extrachromosomally as double‐minute chromosomes (dmin) or intrachromosomally in the form of homogeneously staining regions (hsrs). Approximately one‐half of our oral squamous cell carcinomas (OSCCs) are characterized by amplification of band 11q13, usually as an hsr located entopically (occurring or situated at the normal chromosomal site, as opposed to ectopically). Using chromosomal fluorescence in situ hybridization (FISH), we confirmed the amplification of the cyclin D1 (CCNDx1/PRAD1) and fibroblast growth factor types 3 and 4 (FGF3/INT2 and FGF4/HSTF1) genes within the 11q13 amplicon in our series of primary OSCCs and derived cell lines. The human RIN1 gene was isolated as an RAS interaction/interference protein in a genetic selection in yeast and has been described as a putative effector of both the RAS and ABL oncogenes. We mapped RIN1 to 11q13.2. FISH analysis of 10 11q13‐amplified OSCC cell lines revealed high‐level RIN1 amplification in two cell lines. Three additional cell lines have what appear to be duplications and/or low‐level amplification of RIN1, visible in both interphase and metaphase cells. The hybridization pattern of RIN1 on the metaphase chromosomes is particularly revealing; RIN1 signals flank the 11q13 hsr, possibly as a result of an inverted duplication. The gene amplification model of Coquelle et al. (1997) predicted that gene amplification occurs by breakage‐fusion‐bridge (BFB) cycles involving fragile sites. Our data suggest that the pattern of gene amplification at 11q13 in OSCC cell lines is consistent with a BFB model. RIN1 appears to be a valuable probe for investigating the process of gene amplification in general and, specifically, 11q13 amplification in oral cancer. Genes Chromosomes Cancer 28:153–163, 2000. © 2000 Wiley‐Liss, Inc.

High-resolution mapping of the 11q13 amplicon and identification of a gene, TAOS1 , that is amplified and overexpressed in oral cancer cells

“…Our findings also suggest the presence of two or more as-yet-unidentified breakage hotspots or fragile sites that may be responsible for the breakpoints defining the 11q13 amplicon core. The observation of consistent breakpoints also supports our previous hypothesis that 11q13 amplification arises as a result of BFB cycles in OSCC (30).…”

Localization of deletion to a 300 Kb interval of chromosome 11q13 in cervical cancer

“…It has been suggested that the fragile sites form boundaries of genomic amplifications (Coquelle et al, 1997;Shuster et al, 2000). A breakage-fusion-bridge mechanism of amplification at 11q13 possibly involves breaks at proximal 11q13 (FRA11A) and at INT2 (FRA11H) (Shuster et al, 2000). We speculate therefore that the allelic imbalance at the INT2 locus in some of the primary tumors was preceded by a deletion at D11S913.…”

“…Amplification of this genomic region is observed in a number of human tumors (Shuster et al, 2000). It has been suggested that the fragile sites form boundaries of genomic amplifications (Coquelle et al, 1997;Shuster et al, 2000).…”

“…Amplification of this genomic region is observed in a number of human tumors (Shuster et al, 2000). It has been suggested that the fragile sites form boundaries of genomic amplifications (Coquelle et al, 1997;Shuster et al, 2000). A breakage-fusion-bridge mechanism of amplification at 11q13 possibly involves breaks at proximal 11q13 (FRA11A) and at INT2 (FRA11H) (Shuster et al, 2000).…”

Gene amplification and overexpression of protein phosphatase 1α in oral squamous cell carcinoma cell lines

“…A CEP11 probe labeled with SpectrumGreen s from Vysis was used for enumerating the chromosome 11 centromere. The labeled BAC clone and CEP11 were then used as probes for FISH using standard procedures described previously (Shuster et al, 2000;Reshmi et al, 2004). Approximately 200 interphase nuclei were analysed for each sample.…”