Helicobacter pylori-stimulated EGF receptor transactivation requires metalloprotease cleavage of HB-EGF C. Wallasch, a, * ,1 J.E. Crabtree, b,1 D. Bevec, a P.A. Robinson, b H. Wagner, c and A. Ullrich d a Axxima Pharmaceuticals AG, Am Klopferspitz 19, 82152 Martinsried, Germany b Molecular Medicine Unit, St. James’s University Hospital, Leeds, LS9 7TF, UK c Institute for Medical Microbiology, Immunology and Hygiene, Technical University of Munich, Trogerstr. 9, 81675 Munich, Germany d Department of Molecular Biology, Max–Planck-Institute for Biochemistry, Am Klopferspitz 18a, 82152 Martinsried, Germany Accepted 17 June 2002 Abstract Helicobacter pylori has a major aetiological role in human gastric carcinogenesis but the cellular and molecular pathways by which infection promotes transformation remain to be resolved. This study demonstrates that H. pylori exposure to MKN-1, ST42, and MKN-28 gastric epithelial tumour cells results in the activation of HB-EGF gene expression and EGFR tyrosine phospho- rylation. These cell responses are induced by both cagPAI positive and cagPAI negative H. pylori strains and are dependent on cell surface expression of the HB-EGF precursor. The induction of HB-EGF gene transcription by H. pylori requires metalloprotease-, EGFR-, and Mek1-activities, indicating the involvement of the ‘‘triple membrane passing signal’’ (TMPS) for EGFR transacti- vation. Moreover, the release of the inflammatory cytokine IL-8 by cells exposed to H. pylori is significantly impaired by inhibitors of TMPS pathway elements. Our findings support a model in which H. pylori triggers constitutive EGFR signal activation, which enhances IL-8 production, and initiates neoplastic transformation of gastric epithelial cells. Ó 2002 Elsevier Science (USA). All rights reserved. Keywords: Helicobacter pylori; EGFR; Transactivation; Gastric cancer; Triple membrane passing signal; HB-EGF; Metalloprotease Infection with the gastric bacterium Helicobacter pylori, the causative agent of chronic gastritis, is as- sociated with increased risk of developing distal gastric cancer [1–3]. The International Agency for Research on Cancer has classified H. pylori as a type I carcinogen [4]. Recent studies show that the risk of cancer is greatest in infected subjects with non-ulcer dyspepsia or gastric ulceration who develop severe gastric atro- phy and intestinal metaplasia [5]. Both bacterial viru- lence factors such as the cag pathogenicity island (PAI) [6–9] and polymorphisms in the interleukin-1 loci as- sociated with overexpression of IL-1 and hypochlo- rhydria [10,11] have been linked to increased risk of developing gastric atrophy and/or intestinal type gas- tric cancer. The mechanism by which H. pylori promotes the development of gastric cancer is presently unclear. In- fection in humans is associated with increased prolif- eration of gastric epithelial cells [12,13] and increased gastric mucosal levels of epidermal growth factor (EGF) protein and EGF receptor (EGFR) transcripts [14]. Gastric expression of EGF-related peptides am- phiregulin (AR) [15,16] and heparin-binding EGF (HB- EGF) [17] are also increased in patients with H. pylori infection and/or gastric cancer. The increased expres- sion of EGF and related peptides, which act via the EGFR, are thought to have an important role in mu- cosal repair [18]. However, overexpression of HB-EGF in human gastric cancer [17] and hypergastrinaemic transgenic mice which develop gastric cancer [19] sug- gests that EGFR signalling may play an important role in progression to gastric neoplasia. Interestingly, in hypergastrinaemic transgenic mice, not only does gas- tric Helicobacter infection accelerate the progression to atrophy and gastric cancer [19], but the increase in Biochemical and Biophysical Research Communications 295 (2002) 695–701 www.academicpress.com BBRC * Corresponding author. Fax: +49-89-740-165-20. E-mail address: wallasch@axxima.com (C. Wallasch). 1 Equal contributors. 0006-291X/02/$ - see front matter Ó 2002 Elsevier Science (USA). All rights reserved. PII:S0006-291X(02)00740-4