Evaluation of HER2, MDM2, MYC, MET and TP53 gene copy number alterations in gastric cancer patients

Gastric cancer (GC) is considered as one of the most common types of cancer worldwide with poor prognosis and generally limited treatment options. Recent studies have indicated that HER2, MDM2, MYC, MET, and TP53 play an important role in the development of gastric cancer. Therefore, the aim of this study was to evaluate the incidence of amplification/deletion of these genes in patients with gastric cancer.

In this descriptive study, a total of 37 gastric cancer tissue samples from GC patients including 23 males (62.2%) and 14 females (37.8%) referred to the Hematology-Oncology and Stem Cell Research Center of Shariati Hospital, Tehran, from March 2015 to February 2016 were evaluated. The patient's age at diagnosis ranged from 33 to 85 years (median: 65 years). The amplification pattern of HER2, MDM2, MYC and MET genes and TP53 deletion were investigated by fluorescence in situ hybridization (FISH) technique performed on 3 to 5 micron section obtained from formalin-fixed and paraffin-embedded cancer tissues.

The tumors were preferably identified at the distal stomach (54.05%) in comparison to tumors arising from the gastric cardia. The tumor size varied between 2 and 5 cm (average, 3.5 cm). Seven of the cases (19%) had advanced tumors at the time of diagnosis. HER2, MDM2, MYC, MET and TP53 copy number alteration were successfully determined in all samples obtained from the GC patients. HER2, MDM2, and c-MYC genes were amplified in 2 (5.41%), 1 (2.7%) and 3 (8.11%) of 37 patient samples, however, MET gene amplification and TP53 deletion were not observed in the obtained GC tissue samples. Co-amplification of HER2, MDM2, and MYC genes, and co-amplification of HER2 and MYC genes were detected in one patient.

The results of this study indicate the low frequency of MDM2, HER2 and MYC genes in gastric cancer patient and their copy number alterations may provide diagnostic and prognostic marker for GC patients.