Helicobacter pylori membrane protein 1: A new carcinogenic factor of Helicobacter pylori

Considering a suspected link between Helicobacter pylori infection and huma n stomach cancer, a new H. pylori gene for membrane protein 1 (HP-MP1) was recently cloned. Because HP-MP1 induces release of inflammatory cytokines a nd tumor necrosis factor-alpha acts as both initiator and tumor promoter, w e studied the possible involvement of HP-MP1 in carcinogenesis of H. pylori . Two cell lines, BALB/3T3 cells as control and v-Ha-ras-transfected BALB/3 T3 cells (Bhas 42 cells) as putative initiated cells, were each transfected with HP-MP1, urease B genes, or vector alone. All of the Bhas/mpl clones s howed strong expression of tumor necrosis factor-alpha gene and produced tu mors in 100% of nude mice. Two Bhas/ure clones showed weak tumorigenicity; the other Bhas and BALB clones showed none. Results indicate strong carcino genic activity of HP-MP1 in cooperation with viral Ras protein and weak act ivity of urease B.