Functional Significance of Metastasis-inducing S100A4(Mts1) in Tumor-Stroma Interplay

Abstract

Causal implication of S100A4 in inducing metastases was convincingly shown previously. However, the mechanisms that associate S100A4 with tumor progression are not well understood. S100A4 protein, as a typical member of the S100 family, exhibits dual, intracellular and extracellular, functions. This work is focused on the extracellular function of S100A4, in particular its involvement in tumor-stroma interplay in VMR (mouse adenocarcinoma cell line) tumor cells, which exhibit stroma-dependent metastatic phenotype. We demonstrated the reciprocal influence of tumor and stroma cells where tumor cells stimulate S100A4 secretion from fibroblasts in culture. In turn, extracellular S100A4 modifies the cytoskeleton and focal adhesions and triggers several other events in tumor cells. We found stabilization of the tumor suppressor protein p53 and modulation of its function. In particular, extracellular S100A4 down-regulates the pro-apoptotic bax and the angiogenesis inhibitor thrombospondin-1 genes. For the first time, we demonstrate here that the S100A4 protein added to the extracellular space strongly stimulates proteolytic activity of VMR cells. This activity most probably is associated with matrix metalloproteinases and, in particular, with matrix metalloproteinase-13. Finally, the application of the recombinant S100A4 protein confers stroma-independent metastatic phenotype on VMR tumor cells. In conclusion, our results indicate that metastasis-inducing S100A4 protein plays a pivotal role in the tumor-stroma environment. S100A4 released either by tumor or stroma cells triggers pro-metastatic cascades in tumor cells.Metastatic dissemination of cancer cells results in incurable disease and becomes one of the leading causes of cancer patient deaths. Studies on genes and their protein products involved in this process are of great importance.Causal implication of S100A4 (mts1, CAPL, pEL98, Calvasculin, p9Ka, and FSP1) in metastatic tumor progression was demonstrated by several approaches. Transfection of rodent and human non-metastatic tumor cell lines with S100A4 converts their phenotype to metastatic cells, and contrariwise, the antisense-and ribozyme-mediated mts1-inactivation abolish the metastatic potential of metastatic tumor cells (1-4). Tumors developed in transgenic mice bearing exogenous S100A4 gene acquired metastatic phenotype (5, 6). The tight association of S100A4 with metastasis allows us to rate it among the most reliable prognostic markers. A high level of S100A4 in various types of cancers (breast, esophageal, gastric, colorectal, bladder, gallbladder, and lung) correlates with unfavorable prognosis and lethality (7-11). S100A4 belongs to the S100 family of Ca 2ϩ -binding proteins that comprises 20 members. They are involved in the regulation of various important cellular functions such as cell growth, cell-cell communication, energy metabolism, contraction, neurite outgrowth, and cell motility (for review see Refs. 12-14). S100A4 protein, as a typical member of the S100 family, exerts dual, intracellul...

Metastasis-associated S100A4 is a specific amine donor and an activity-independent binding partner of transglutaminase-2

“…The extracellular role of S100A4 is less described, its specific receptor(s) and mode of internalization and secretion are not well-known. Secreted S100A4 acts as a paracrine and autocrine factor inducing angiogenesis, cell migration, invasion, as well as neurite outgrowth [11]. Its overexpression is strongly associated with certain inflammatory diseases, epithelial to mesenchymal transition and tumor metastasis, and it is considered as a prognostic marker for poor patient survival in a number of cancer metastases [12].…”

The metastasis associated protein S100A4: role in tumour progression and metastasis

“…S100A4 can also be secreted and once extracellular can affect several facets of tumour progression such as angiogenesis, stimulation of cell motility, upregulation of matrix metalloproteinases (MMPs), modulation of tumour-related transcription factors, and potentially as a stromal factor Belot et al, 2002;Schmidt-Hansen et al, 2004a, b). S100A4 may be released from both tumour and/or stroma cells by an as yet undetermined mechanism.…”

Opposite roles of metastasin (S100A4) in two potentially tumoricidal mechanisms involving human lymphocyte protein Tag7 and Hsp70

“…This small (Ϸ10 kDa) readily dimerizing polypeptide can take part in quite diverse processes both inside and outside the cell (2,3). Particularly, it has been implicated in tumor metastasis (1,(4)(5)(6)(7).…”