Evaluation of human endogenous retrovirus gene expression in gastric cancer and marginal tissues

Abstract

Gastric cancer is the fifth most common cancer worldwide and the second leading cause of death. Different biomarkers have been proposed for the early detection of cancers. There are several important families of endogenous retroviruses in the human genome that are increasingly being used in cancer research. The aim of this study was to evaluate the expression of human endogenous retroviral genes in gastric malignancies. Materials and Methods: In this study, from patients with gastrointestinal problems referred for endoscopy, after obtaining consent, tissue samples suspected of gastric cancer were taken from the desired area and normal margins. The collected samples were immediately placed in a nitrogen tank and transferred to a freezer of negative 70 for later use. A checklist containing patient information including previous medical history, medication use, lifestyle, and micro-risk factors was completed. After receiving the pathology response and confirming the cancer in the target tissue using commercial tresol solution, RNA was extracted and cDNA synthesis was performed immediately to maintain the quality of the samples. Specific primers were designed for the target sequences and then the desired HERVs were amplified using quantitative PCR using specific primers. After normalization with the reference gene (GAPDH gene), the results were analyzed with the advice of a statistical consultant and the final result was reported. Results: In this study, out of 40 patients, most of the patients were under 65 years old and were male. Intestinal malignancy had the highest frequency. Half of the masses were larger or equal to 5 cm in size. 60% had lymph node metastasis and 57.5% had distant metastasis. The mean expression of HERV-E and HERV-K in tumor tissue showed a statistically significant difference compared to tumor margins. The expression of HERV-E in the tumor margin tissue was statistically significant with age and sex. Ordinal logistic regression analysis was significant to evaluate the predictability of HERK genes in hysterology.