Interrelationship between chromosome 8 aneuploidy,C-MYC amplification and increased expression in individuals from northern Brazil with gastric adenocarcinoma

AIM: To investigate chromosome 8 numerical aberra- tions, C-MYC oncogene alterations and its expression in gastric cancer and to correlate these findings with histo- pathological characteristics of gastric tumors. METHODS: Specimens were collected surgically from seven patients with gastric adenocarcinomas. Immu- nostaining for C-MYC and dual-color fluorescence in situ hybridization (FISH) for C-MYC gene and chromosome 8 centromere were performed. RESULTS: All the cases showed chromosome 8 aneu- ploidy and C-MYC amplification, in both the diffuse and intestinal histopathological types of Lauren. No significant difference (P < 0.05) was observed between the level ofchromosome 8 ploidy and the site, stage or histological type of the adenocarcinomas. C-MYC high amplification, like homogeneously stained regions (HSRs) and double minutes (DMs), was observed only in the intestinal-type. Structural rearrangement of C-MYC, like translocation, was observed only in the diffuse type. Regarding C-MYC gene, a significant difference (P < 0.05) was observed between the two histological types. The C-MYC protein was expressed in all the studied cases. In the intestinal- type the C-MYC immunoreactivity was localized only in the nucleus and in the diffuse type in the nucleus and cytoplasm. CONCLUSION: Distinct patterns of alterations between intestinal and diffuse types of gastric tumors support the hypothesis that these types follow different genetic path- ways.

Identification of IL11RA and MELK amplification in gastric cancer by comprehensive genomic profiling of gastric cancer cell lines

AIM To identify common copy number alterations on gastric cancer cell lines.METHODS Four gastric cancer cell lines(ACP02, ACP03, AGP01 and PG100) underwent chromosomal comparative genome hybridization and array comparative genome hybridization. We also confirmed the results by fluorescence in situ hybridization analysis using the bacterial artificial chromosome clone and quantitative real time PCR analysis.RESULTS The amplification of 9p13.3 was detected in all cell lines by both methodologies. An increase in the copy number of 9p13.3 was also confirmed by fluorescence in situ hybridization analysis. Moreover, the interleukin 11 receptor alpha(IL11RA) and maternal embryonic leucine zipper kinase(MELK) genes, which are present in the 9p13.3 amplicon, revealed gains of the MELK gene in all the cell lines studied. Additionally, a gain in the copy number of IL11 RA and MELK was observed in 19.1%(13/68) and 55.9%(38/68) of primary gastric adenocarcinoma samples, respectively. CONCLUSION The characterization of a small gain region at 9p13.3 in gastric cancer cell lines and primary gastric adenocarcinoma samples has revealed MELK as a candidate target gene that is possibly related to the development of gastric cancer.