Protein profile and search for diagnostic markers in gastric cancer patients in Algeria

摘要

Gastric cancer is one of the most common cancers in the world with one million new cases each year. It remains the second leading cause of death by cancer for both sexes. In Algeria, it represents 5% of all cancers listed and it comes in the fifth position with 1430 new cases each year. Gastric cancer was associated with Epstein-Barr virus (EBV) with an incidence of 10 to 18%. The LMP-1 protein is considered as the major EBV oncogene. Thanks to its signaling, LMP1 presents immortalization and transformation properties, able of inhibiting cell differentiation. The most promising approach to reduce mortality from gastric cancer is the early diagnosis by identifying specific and sensitive biomarkers. It is in this context that we first realized electrophoresis on cellulose acetate plates of the sera of patients with gastric cancer. The proteinogram obtained are, in general, very similar and they have a uniform appearance like paths known to be normal. Some of them have hypo-proteinemia and hypo-albuminemia in relation with inflammation and protein losses by digestive bleeding. In a second step, we performed SDS-PAGES to compare protein profiles of sera of gastric cancer subjects with those of healthy subjects. We have noted the existence of an additional band of 27 kDa in 20% of gastric cancer topics we found a disparity concerning the 18 kDa band which is present in 65% of patients and only in 43% of subjects healthy. Then, we performed ELISA on sera and on protein extracts of gastric biopsies to look for the presence of the LMP1 protein. The latter was detected in about 50% of cases. In healthy subjects, the samples were negative. By statistical tests, we have shown that the protein is expressed without regard to the patient's age or stage of cancer progression. LMP-1 may thus, serve as a biomarker for the diagnosis of EBV positive gastric cancer.