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A novel amplicon at 8p22-23 results in overexpression of cathepsin B in esophageal adenocarcinoma.

ABSTRACT: Cathepsin B (CTSB) is overexpressed in tumors of the lung, prostate, colon, breast, and stomach. However, evidence of primary genomic alterations in the CTSB gene during tumor initiation or progression has been lacking. We have found a novel amplicon at 8p22-23 that results in CTSB overexpression in esophageal adenocarcinoma. Amplified genomic NotI-HinfI fragments were identified by two-dimensional DNA electrophoresis. Two amplified fragments (D4 and D5) were cloned and yielded unique sequences. Using bacterial artificial chromosome clones containing either D4 or D5, fluorescent in situ hybridization defined a single region of amplification involving chromosome bands 8p22-23. We investigated the candidate cancer-related gene CTSB, and potential coamplified genes from this region including farnesyl-diphosphate farnesyltransferase (FDFT1), arylamine N-acetyltransferase (NAT-1), lipoprotein lipase (LPL), and an uncharacterized expressed sequence tag (D8S503). Southern blot analysis of 66 esophageal adenocarcinomas demonstrated only CTSB and FDFT1 were consistently amplified in eight (12.1%) of the tumors. Neither NAT-1 nor LPL were amplified. Northern blot analysis showed overexpression of CTSB and FDFT1 mRNA in all six of the amplified esophageal adenocarcinomas analyzed. CTSB mRNA overexpression also was present in two of six nonamplified tumors analyzed. However, FDFT1 mRNA overexpression without amplification was not observed. Western blot analysis confirmed CTSB protein overexpression in tumor specimens with CTSB mRNA overexpression compared with either normal controls or tumors without mRNA overexpression. Abundant extracellular expression of CTSB protein was found in 29 of 40 (72. 5%) of esophageal adenocarcinoma specimens by using immunohistochemical analysis. The finding of an amplicon at 8p22-23 resulting in CTSB gene amplification and overexpression supports an important role for CTSB in esophageal adenocarcinoma and possibly in other tumors.

SUBMITTER: Hughes SJ

PROVIDER: S-EPMC22845 | biostudies-literature | 1998 Oct

REPOSITORIES: biostudies-literature

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A novel amplicon at 8p22-23 results in overexpression of cathepsin B in esophageal adenocarcinoma.

Hughes S J SJ Glover T W TW Zhu X X XX Kuick R R Thoraval D D Orringer M B MB Beer D G DG Hanash S S

Proceedings of the National Academy of Sciences of the United States of America 19981001 21

Cathepsin B (CTSB) is overexpressed in tumors of the lung, prostate, colon, breast, and stomach. However, evidence of primary genomic alterations in the CTSB gene during tumor initiation or progression has been lacking. We have found a novel amplicon at 8p22-23 that results in CTSB overexpression in esophageal adenocarcinoma. Amplified genomic NotI-HinfI fragments were identified by two-dimensional DNA electrophoresis. Two amplified fragments (D4 and D5) were cloned and yielded unique sequences. ...[more]

PMID: 9770500

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Project description:Ninety percent of patients with esophageal adenocarcinoma ultimately die of their disease, highlighting the need for novel therapeutic targets. The goal of this study was to define the functional significance of overexpression of Dickkopf-3 (DKK3) in esophageal adenocarcinoma.DKK3 expression was analyzed by real-time polymerase chain reaction in 95 chemonaive and 21 chemoresistant esophageal adenocarcinomas. The esophageal adenocarcinoma cell line OE33 was stably transfected with DKK3 (OE33/DKK3) and evaluated using WST-1 (Roche, Basel, Switzerland), Matrigel (BD Biosciences, San Jose, Calif), endothelial tube formation, and chemosensitivity assays. Tumorigenesis was evaluated by injecting 1 × 10(6) OE33/DKK3 and vector cells in NOD/SCID? mice.DKK3 was overexpressed (>2-fold) in 75.8% (72/95) of esophageal adenocarcinomas. DKK3 protein was present at moderate to high levels in 46.8% (29/62) of esophageal adenocarcinomas on tissue microarray. Stable transfection of DKK3 significantly increased proliferation (P < .05) and Matrigel invasion (P < .001). Levels of SMAD4, a key mediator of the transforming growth factor-ß pathway, increased after activin treatment of OE33/DKK3, and siSMAD4 significantly decreased Matrigel invasion, suggesting that DKK3 acts through the transforming growth factor-? pathway. OE33/DKK3 cells increased endothelial tube formation and were significantly more resistant to 5-fluorouracil and cisplatin, and DKK3 expression was significantly higher in chemoresistant esophageal adenocarcinomas (P < .005). In NOD/SCID? mice, OE33/DKK3 cells resulted in tumors at all sites (8/8), whereas vector cells grew in only 1 of 8 sites. Nodal metastases were also significantly increased in patients with esophageal adenocarcinomas highly overexpressing DKK3, 28 of 32 (88%) versus 42 of 63 (68%) (P < .05).These findings suggest that DKK3 may be important in mediating invasion in esophageal adenocarcinoma and could be a novel target in the treatment and prevention of metastatic disease.

Project description:Multiple lines of evidence have implicated the short arm of chromosome 8 as harboring genes important in prostate carcinogenesis. Although most of this evidence comes from the identification of frequent somatic alterations of 8p loci in prostate cancer cells (e.g., loss of heterozygosity), studies have also suggested a role for 8p genes in mediation of inherited susceptibility to prostate cancer. To further examine this latter possibility, we performed linkage analyses, in 159 pedigrees affected by hereditary prostate cancer (HPC), using 24 markers on the short arm of chromosome 8. In the complete set of families, evidence for prostate cancer linkage was found at 8p22-23, with a peak HLOD of 1.84 (P=.004), and an estimate of the proportion of families linked (alpha) of 0.14, at D8S1130. In the 79 families with average age at diagnosis >65 years, an allele-sharing LOD score of 2.64 (P=.0005) was observed, and six markers spanning a distance of 10 cM had LOD scores >2.0. Interestingly, the small number of Ashkenazi Jewish pedigrees (n=11) analyzed in this study contributed disproportionately to this linkage. Mutation screening in HPC probands and association analyses in case subjects (a group that includes HPC probands and unrelated case subjects) and unaffected control subjects were carried out for the putative prostate cancer-susceptibility gene, PG1, previously localized to the 8p22-23 region. No statistical differences in the allele, genotype, or haplotype frequencies of the SNPs or other sequence variants in the PG1 gene were observed between case and control subjects. However, case subjects demonstrated a trend toward higher homozygous rates of less-frequent alleles in all three PG1 SNPs, and overtransmission of a PG1 variant to case subjects was observed. In summary, these results provide evidence for the existence of a prostate cancer-susceptibility gene at 8p22-23. Evaluation of the PG1 gene and other candidate genes in this area appears warranted.

Dataset Information

A novel amplicon at 8p22-23 results in overexpression of cathepsin B in esophageal adenocarcinoma.

Publications

A novel amplicon at 8p22-23 results in overexpression of cathepsin B in esophageal adenocarcinoma.

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