Stromelysin-3 over-expression enhances tumourigenesis in MCF-7 and MDA-MB-231 breast cancer cell lines: involvement of the IGF-1 signalling pathway

BMC Cancer Stromelysin-3 over-expression enhances tumourigenesis in MCF-7 and MDA-MB-231 breast cancer cell lines: involvement of the IGF-1 signalling pathway Grit Kasper 2 Matthias Reule 1 Miriam Tschirschmann 0 Niels Dankert 2 Karen Stout-Weider 6 Roland Lauster 0 Evelin Schrock 5 Detlev Mennerich 4 Georg N Duda 2 Kerstin E Lehmann 3 0 University for Technologies , Berlin , Germany 1 Astex Therapeutics , Cambridge , UK 2 Musculoskeletal Research Center Berlin , Charité - Universitätsmedizin Berlin, Berlin , Germany 3 Center for Cardiovascular Research , Charité - Universitätsmedizin Berlin, Berlin , Germany 4 Boehringer Ingelheim Pharma GmbH & CoKG , Biberach , Germany 5 Institute of Clinical Genetics, Technische Universität , Dresden , Germany 6 Institute of Medical Genetics , Charité - Universitätsmedizin Berlin, Berlin , Germany Background: Stromelysin-3 (ST-3) is over-expressed in the majority of human carcinomas including breast carcinoma. Due to its known effect in promoting tumour formation, but its impeding effect on metastasis, a dual role of ST-3 in tumour progression, depending on the cellular grade of dedifferentiation, was hypothesized. Methods: The present study was designed to investigate the influence of ST-3 in vivo and in vitro on the oestrogendependent, non-invasive MCF-7 breast carcinoma cell line as well as on the oestrogen-independent, invasive MDA-MB231 breast carcinoma cell line. Therefore an orthotopic human xenograft tumour model in nude mice, as well as a 3D matrigel cell culture system, were employed. Results: Using both in vitro and in vivo techniques, we have demonstrated that over-expression of ST-3 in MCF-7 and MDA-MB-231 cells leads to both increased cell numbers and tumour volumes. This observation was dependent upon the presence of growth factors. In particular, the enhanced proliferative capacity was in MCF-7/ST-3 completely and in MDAMB-231/ST-3 cells partially dependent on the IGF-1 signalling pathway. Microarray analysis of ST-3 over-expressing cells revealed that in addition to cell proliferation, further biological processes seemed to be affected, such as cell motility and stress response. The MAPK-pathway as well as the Wnt and PI3-kinase pathways, appear to also play a potential role. Furthermore, we have demonstrated that breast cancer cell lines of different differentiation status, as well as the nontumourigenic cell line MCF-10A, have a comparable capability to induce endogenous ST-3 expression in fibroblasts. Conclusion: These data reveal that ST-3 is capable of enhancing tumourigenesis in highly differentiated "early stage" breast cancer cell lines as well as in further progressed breast cancer cell lines that have already undergone epithelialmesenchymal transition. We propose that ST-3 induction in tumour fibroblasts leads to the stimulation of the IGF-1R pathway in carcinoma cells, thus enhancing their proliferative capacity. In addition, further different cellular processes seem to be activated by ST-3, possibly accounting for the dual role of ST-3 in tumour progression and metastasis. Background The human protein family of matrix metalloproteinases (MMPs) includes at least 25 members that are believed to play a role in the various stages of tumourigenesis [ 1,2 ]. Most of these zinc-dependent endopeptidases cleave more than one extracellular matrix (ECM) component and each ECM component is generally cleaved by more than one MMP. Aside from matrix degradation, MMPs play an important role in releasing growth factors, such as TGF-β or VEGF, or other biologically active factors [ 3,4 ]. The effect of over-expression or inhibition of MMPs in tumours might be complex, as these proteases are able to promote and impede tumour relevant processes such as proliferation, apoptosis, angiogenesis and metastasis [ 5 ]. Stromelysin-3 (ST-3, MMP-11) was originally identified as a breast cancer associated gene, which is over-expressed in more than 90% of invasive breast carcinomas [ 6 ]. Recent studies have shown that ST-3 over-expression is found in most human carcinomas [ 7 ]. Expression of the gene has also been detected in fibroblasts at the invasion front of tumours in close proximity to carcinoma cells [ 6 ]. Furthermore, it has been shown that ST-3 expression is induced in fibroblasts by co-culturing with breast carcinoma cells [ 8,9 ]. Although ST-3 was discovered more than a decade ago and assigned to the family of MMPs due to sequence homologies, no ECM component has yet been identified that is cleaved by full length human ST-3 [10]. However, ST-3 has been found to cleave IGFBP-1, thereby releasing IGF-1 [ 11 ]. IGF-1 is known to stimulate proliferation, enhancing survival and migration of cancer cells [ 12 ]. Despite a limited knowledge of ST-3 substrates and mode of action, an in vitro study has demonstrated that ST-3 over-expression in MCF-7 cells is capable of increasing cell survival under serum starvation conditions [ (...truncated)