Abstract 2094: Regulation of site-specific liver metastasis by collagen IV-conveyed signals

Abstract The liver is a primary site of metastasis for some of the most common human malignancies. At present, surgical resection is the most effective curative option for liver metastases, but most patients with liver metastases still succumb to their disease. A better understanding of the underlying biology is essential for design of more effective therapy. We previously identified basement membrane type IV collagen α1/α2 expression levels as determinants of the liver colonizing potential in a murine lung carcinoma model (1) and observed high collagen IV expression levels in surgical specimens of liver metastases from diverse tumor types. The aim of this study was to elucidate the functional relevance of increased collagen IV expression to liver metastases formation. We reported that collagen IV α1/α2 overexpression in non-metastatic lung carcinoma M-27 (M27colIV) cells increased specifically their liver (but not lung) metastasizing potential. A transcriptome analysis was therefore performed on these cells in order to identify changes to gene expression that could account for the newly acquired metastatic potential. This analysis revealed that type IV collagen levels regulated the expression of multiple genes. Prominent among them were genes encoding for chemokines such as CCL-5 and CCL-7 and for growth factors such as amphiregulin (AREG) that were all upregulated by ≥ 3 fold. These changes were validated at the RNA and protein levels using qPCR and Western blotting, respectively. When the expression of these genes in M27colIV cells was subsequently silenced using shRNA, a significant decrease (5-10 folds) was observed in their ability to generate experimental liver metastases, as compared to wild type or mock-transfected cells and they failed to develop metastases in 40-50 % of injected mice. A similar correlation between CCL-5 and CCL-7 expression levels and liver metastases formation was also noted in human colon carcinoma cell lines. The results identify a type IV collagen-regulated gene expression signature that promotes liver metastasis and suggest that collagen IV-induced changes in chemokine and growth factor production levels mediate this effect. They provide a rationale for further exploration of the clinical utility of CCL-5, CCL-7 and AREG as targets in the management of liver metastases. Supported by a grant from the Canadian Institute for Health Research (to PB) and a Henry R. Shibata Cedars Cancer Fellowship (to RR). REFERENCES 1. Burnier JV, Wang N, Michel RP, Hassanain M, Li S, Lu Y, et al. Type IV collagen-initiated signals provide survival and growth cues required for liver metastasis. Oncogene. 2011;30:3766-83. Citation Format: Roni F. Rayes, Ni Wang, Julia V. Burnier, France Bourdeau, Pnina Brodt. Regulation of site-specific liver metastasis by collagen IV-conveyed signals. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 2094. doi:10.1158/1538-7445.AM2014-2094