Ulrike Sack

Novel Effect of Antihelminthic Niclosamide on S100A4-Mediated Metastatic Progression in Colon Cancer

BACKGROUND Metastasis formation in colon cancer severely reduces the survival rate in patients. S100A4, a calcium-binding protein, is implicated in promoting metastasis formation in colon cancer. METHODS To identify a transcription inhibitor of S100A4, high-throughput screening of 1280 pharmacologically active compounds was performed using a human colon cancer cell line expressing a S100A4 promoter-driven luciferase (LUC) reporter gene construct (HCT116-S1004p-LUC). Niclosamide, an antihelminthic agent, was identified as a potential candidate. Colon cancer cell lines (HCT116, SW620, LS174T, SW480, and DLD-1) were treated with 1 μM niclosamide to analyze the effect on S100A4 mRNA and protein expression by quantitative reverse transcription-polymerase chain reaction and immunoblot assays, and effects on cell migration, invasion, proliferation, and colony formation were also assessed in vitro. The effect of niclosamide on liver metastasis was assessed in a xenograft mouse model of human colon cancer (n = 8 mice) by in vivo imaging. The long-term effect of niclosamide on metastasis formation after discontinued treatment was quantified by scoring, and overall survival (n = 12 mice) was analyzed by Kaplan-Meier method after discontinuation of treatment. All statistical tests were two-sided. RESULTS Reduced S100A4 mRNA and protein expression, and inhibited cell migration, invasion, proliferation, and colony formation were observed in niclosamide-treated colon cancer cells in vitro. In vivo imaging of niclosamide-treated mice showed reduced liver metastasis compared with solvent-treated control mice (n = 4 mice per group). Compared with the control group, discontinuation of treatment for 26 days showed reduced liver metastasis formation in mice (n = 6 mice per group) (control vs discontinuous treatment, mean metastasis score = 100% vs 34.9%, mean difference = 65.1%; 95% confidence interval [CI] = 18.4% to 111.9%, P < .01) and increased overall survival (n = 6 mice per group; control vs discontinuous treatment, median survival = 24 vs 46.5 days, ratio = 0.52, 95% CI = 0.19 to 0.84, P = .001). CONCLUSION Niclosamide inhibits S100A4-induced metastasis formation in a mouse model of colon cancer and has therapeutic potential.

S100A4-induced cell motility and metastasis is restricted by the Wnt/β-catenin pathway inhibitor calcimycin in colon cancer cells

Calcimycin restricts Wnt/β-catenin–regulated S100A4 expression, leading to reduced S100A4-mediated cell migration and invasion in colon cancer cells, as well as to inhibition of metastasis formation in xenografted mice.

In vivo imaging of colorectal cancer growth and metastasis by targeting MACC1 with shRNA in xenografted mice

We previously identified the gene metastasis-associated in colon cancer-1 (MACC1) and demonstrated its important role for metastasis prediction in colorectal cancer. MACC1 induces cell motility and proliferation in vitro as well as metastasis in several mouse models. Here we report non-invasive real time imaging of inhibition of colorectal tumor progression and metastasis in xenografted mice by MACC1 shRNA. First, we demonstrated reduction of tumors and liver metastases by endpoint imaging of mice transplanted with MACC1 endogenously high expressing colorectal cancer cells and treated with shRNAs acting on MACC1 or Met. Next, we generated a novel bicistronic IRES vector simultaneously expressing the reporter gene firefly luciferase and MACC1 to ensure a direct correlation of bioluminescence signal with MACC1 expression. We transfected MACC1 endogenously low expressing colorectal cancer cells with this luciferase-IRES-MACC1 construct, transplanted them intrasplenically, and monitored MACC1 induced tumor growth and metastasis by in vivo imaging over time. Transfection of an IRES construct harboring the firefly luciferase reporter gene together with MACC1 lacking the SH3-domain reduced tumor growth and metastasis. Finally, we counteracted the luciferase-IRES-MACC1 induced effects by shRNA targeting MACC1 and monitored reduced tumor growth and metastasis by in vivo imaging over weeks. In summary, the new bicistronic luciferase-IRES-MACC1 construct is suitable for in vivo imaging of tumor progression and metastasis, and moreover, for imaging of therapy response such as treatment with MACC1 shRNA. Thereby, we provide proof-of-concept for employment of this MACC1-based in vivo model for evaluating therapeutic intervention strategies aiming at inhibition of tumor growth and metastasis.

Anti-metastatic treatment in colorectal cancer: targeting signaling pathways.

Colorectal cancer is one of the most common cancers worldwide and one of the leading causes of cancer-related death in the Western world. Tumor progression towards metastasis affects a large number of patients with colorectal cancer and seriously affects their clinical outcome. Therefore, considerable effort has been made towards the development of therapeutic strategies that can decrease or prevent colorectal cancer metastasis. Standard treatment of metastatic colorectal cancer with chemotherapy has been improved in the last 10 years by the addition of new targeted agents. The currently used antibodies bevacizumab, cetuximab and panitumumab target the VEGF and EGFR signaling pathways, which are crucial for tumor progression and metastasis. These antibodies have shown relevant efficacy in both first- and second-line treatment of metastatic colorectal cancer. Additionally, other signaling pathways, including the Wnt and HGF/Met pathways, have a well-established role in colorectal cancer progression and metastasis and constitute, therefore, promising targets for new therapeutic approaches. Several new drugs targeting these pathways, including different antibodies and small-molecule tyrosine kinase inhibitors, are currently being developed and tested in clinical trials. In this review, we summarize the new developments in this field, focusing on the inhibitors that show more promising results for use in colorectal cancer patients.

Abstract 2258: Targeting MACC1: In vivo imaging of distant metastases reduction by MACC1-shRNA in human colon cancer xenografts

We identified the previously undescribed gene MACC1 by a genome-wide search for differentially expressed genes in human colon cancer tissues, metastases and normal tissues. MACC1 plays an important role for metastasis prediction, in particular for early-stage patients. Based on MACC1 mRNA expression in not (yet) metastasized primary colon cancers of stages I, II and III, our negative and positive prediction of the development of metachronous distant metastases was correct to 80% and 74%, respectively. The 5-year-survival for subjects suffering from colon cancer was 80% for MACC1 low expressors, but 15% for individuals with high MACC1 expression in their primary tumors. Moreover, we found MACC1 to act as an inducer of migration, invasion and proliferation in cell culture, and of distant metastases in several xenograft models. MACC1 transcriptionally regulates the receptor tyrosine kinase Met, that activates the HGF/Met signaling pathway resulting in enhanced cell motility, invasion and metastasis. Here we report the reduction of metastasis by using shRNA targeting the metastasis-inducer MACC1 in vivo. MACC1 high expressing human colon cancer cells were transfected with MACC1-shRNA, Met-shRNA, or control-shRNA harboring plasmids, together with luciferase-containing constructs. Cell clones were intrasplenically transplanted into mice. Tumor growth and metastases formation was demonstrated by in vivo imaging. Signals in MACC1-shRNA/luc mice and in Met-shRNA/luc mice originated exclusively from spleen tumors, not from liver metastases, as demonstrated with the isolated organs by luminescence. By contrast, signals in control-shRNA/luc mice originated from spleen tumors and liver metastases. These findings were confirmed by brightfield images, demonstrating reduced tumor growth and metastases development in MACC1-shRNA/luc and Met-shRNA/luc mice compared to control-shRNA/luc mice. In summary, knock down of MACC1 by MACC1-shRNA led to reduction of tumor growth and metastasis in mice, making MACC1-shRNA a useful tool for metastasis intervention of colon cancer. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 2258.