A reporter system evaluates tumorigenesis, metastasis, β-catenin/MMP regulation, and druggability

Cancer invasion, metastasis, and therapy resistance are the crucial phenomena in cancer malignancy. The high-expression of matrix metalloproteinase 9 (MMP9) is a biomarker as well as a causal factor of cancer invasiveness and metastatic activity. However, a regulatory mechanism underlying MMP9 expression in cancer is not clarified yet. Additionally, a new strategy for anti-cancer drug discovery is becoming an important clue. In the present study, we aimed (i) to develop a novel reporter system evaluating tumorigenesis, invasiveness, metastasis, and druggability with a combination of three-dimensional (3D) tumoroid model and Mmp9 promoter and (ii) to examine pharmacological actions of anti-cancer medications using this reporter system. High expression and genetic amplification of MMP9 were found in colon cancer cases. We found that proximal promoter sequences of MMP9 in murine and human contained conserved binding sites for transcription factors β-catenin/TCF/LEF, glucocorticoid receptor (GR), and NF-κB. The murine Mmp9 promoter (-569 to +19) was markedly activated in metastatic colon cancer cells and additionally activated by tumoroid formation and by β-catenin signaling stimulator lithium chloride (LiCl). The Mmp9 promoter-driven fluorescent reporter cells enabled the monitoring of activities of MMP9/gelatinase, tumorigenesis, invasion, and metastasis in allogeneic/syngenic transplantation experiments. We also demonstrated pharmacological actions as follows. ids Dexamethasone and hydrocortisone, steroidal medications binding to GR, inhibited the Mmp9 promoter but did not inhibit tumorigenesis. On the other hand, an antimetabolite 5-fluorouracil, a golden standard for colon cancer chemotherapy, inhibited tumoroid formation but did not inhibit Mmp9 promoter activity. Notably, anti-malaria medication artesunate inhibited both tumorigenesis and the Mmp9 promoter in vitro, potentially through inhibition of β-catenin/TCF/LEF signaling. Thus, this novel reporter system enabled monitoring tumorigenesis, invasiveness, metastasis, key regulatory signalings such as β-catenin/MMP9 axis, and druggability.

This is an Accepted Manuscript of an article published by Mary Ann Liebert