Combinatorial treatment with statins and niclosamide prevents CRC dissemination by unhinging the MACC1-β-catenin-S100A4 axis of metastasis

Colorectal cancer (CRC) is the second-most common malignant disease worldwide, and metastasis is the main culprit of CRC-related death. Metachronous metastases remain to be an unpredictable, unpreventable, and fatal complication, and tracing the molecular chain of events that lead to metastasis would provide mechanistically linked biomarkers for the maintenance of remission in CRC patients after curative treatment. We hypothesized, that Metastasis-associated in colorectal cancer-1 (MACC1) induces a secretory phenotype to enforce metastasis in a paracrine manner, and found, that the cell-free culture medium of MACC1-expressing CRC cells induces migration. Stable isotope labeling by amino acids in cell culture mass spectrometry (SILAC-MS) of the medium revealed, that S100A4 is significantly enriched in the MACC1-specific secretome. Remarkably, both biomarkers correlate in expression data of independent cohorts as well as within CRC tumor sections. Furthermore, combined elevated transcript levels of the metastasis genes MACC1 and S100A4 in primary tumors and in blood plasma robustly identifies CRC patients at high risk for poor metastasis-free (MFS) and overall survival (OS). Mechanistically, MACC1 strengthens the interaction of β-catenin with TCF4, thus inducing S100A4 synthesis transcriptionally, resulting in elevated secretion to enforce cell motility and metastasis. In cell motility assays, S100A4 was indispensable for MACC1-induced migration, as shown via knock-out and pharmacological inhibition of S100A4. The direct transcriptional and functional relationship of MACC1 and S100A4 was probed by combined targeting with repositioned drugs. In fact, the MACC1-β-catenin-S100A4 axis by statins (MACC1) and niclosamide (S100A4) synergized in inhibiting cancer cell motility in vitro and metastasis in vivo. The MACC1-β-catenin-S100A4 signaling axis is causal for CRC metastasis. Selectively repositioned drugs synergize in restricting MACC1/S100A4-driven metastasis with cross-entity potential.

Abstract 2000: Cancer metastasis driven by the novel MEK1 substrate MACC1 is restricted by clinically applicable MEK1 inhibitors

Cancer metastasis is responsible for >90% of cancer deaths and remains a major treatment challenge. In search of new drivers of metastasis we identified the novel, previously undescribed gene Metastasis-Associated in Colon Cancer 1 (MACC1) in human colorectal cancer (CRC). MACC1 induces fundamental processes like proliferation, migration, invasiveness and metastasis in xenografted and transgenic mice. MACC1 has been established by us and many other groups as key player, prognostic and predictive biomarker for tumor progression and metastasis in >20 solid cancer types. Proof-of-concept for MACC1 as a therapeutic target to restrict cancer progression and metastasis was provided by transcriptional and post-transcriptional downregulation of MACC1 for several solid cancers, including CRC. Specific inhibitors targeting MACC1 post-translational protein modifications to restrict tumor growth and metastasis are not identified so far. Here we report the identification of MACC1 as a newly identified substrate of the kinase MEK1 (MAP2K1). MEK1 directly phosphorylates MACC1 leading to accelerated and increased ERK1 activation. Mutating three potential hierarchical MACC1 tyrosine phosphorylation sites abrogates MACC1 dependent target gene expression like MET, cell proliferation and motility in cell culture and importantly, metastasis in mouse xenograft models. Targeting MEK1 by RNAi or by clinically applicable MEK1 inhibitors like AZD6244 and GSK1120212 reduces MACC1 tyrosine phosphorylation and restricts MACC1-induced metastasis formation. Our findings demonstrate that MAP kinase signaling is not linearly leading only to ERK activation, but branches at the level of MEK1. In summary, MACC1 tyrosine phosphorylation is decisive for tumor growth and metastasis. The fundamental finding of MACC1 being a newly identified MEK1 substrate opens new therapeutic options with potential for clinical translation. Targeting MACC1 tyrosine phosphorylation using MEK1 inhibitors thereby intervening in MACC1-induced metastasis aims at the ultimate goal of personalized therapies for inhibition of cancer progression and metastasis, resulting in improved patient survival. Since MACC1 is confirmed as decisive driver for tumor growth and metastasis in a variety of solid cancers, the findings made here for CRC might be translated to further solid tumor types. The usefulness of MACC1 as therapeutic target towards MEK1 inhibitor treatment requires confirmation in clinical trials.

Citation Format: Dennis Kobelt, Daniel Perez-Hernandez, Claudia Fleuter, Mathias Dahlmann, Fabian Zincke, Janice Smith, Rebekka Migotti, Susen Burock, Wolfgang Walther, Gunnar Dittmar, Ulrike S. Stein. Cancer metastasis driven by the novel MEK1 substrate MACC1 is restricted by clinically applicable MEK1 inhibitors [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 2000.

MACC1-the first decade of a key metastasis molecule from gene discovery to clinical translation

Deciphering the paths to metastasis and identifying key molecules driving this process is one important issue for understanding and treatment of cancer. Such a key driver molecule is Metastasis Associated in Colon Cancer 1 (MACC1). A decade long research on this evolutionarily conserved molecule with features of a transcription factor as well as an adapter protein for versatile protein-protein interactions has shown that it has manifold properties driving tumors to their metastatic stage. MACC1 transcriptionally regulates genes involved in epithelial-mesenchymal transition (EMT), including those which are able to directly induce metastasis like c-MET, impacts tumor cell migration and invasion, and induces metastasis in solid cancers. MACC1 has proven as a valuable biomarker for prognosis of metastasis formation linked to patient survival and gives promise to also act as a predictive marker for individualized therapies in a broad variety of cancers. This review discusses the many features of MACC1 in the context of the hallmarks of cancer and the potential of this molecule as biomarker and novel therapeutic target for restriction and prevention of metastasis.