Abstract 5251: CXCL14 as a functional determinant in a novel model of inflammatory, triple negative breast cancer progression

CXCL14 (BRAK) is a cytokine implicated in inflammatory responses, but its contribution to cancer is largely unknown. Recent studies in clinical breast cancer indicate an association between CXCL14 expression and shortened time to metastatic progression, as well as the presence of CXCL14 in a subset of breast epithelial cells with a stem-like phenotype. Using global gene expression profiling, we identified CXCL14 as the most prominently upregulated cytokine in a novel progression model of triple-negative inflammatory and metaplastic breast cancer that we generated. The model comprises tumor cells established from a locally aggressive primary tumor obtained from a patient at the time of initial surgery (TES-1), and tumor cells from the same site at the time of local failure in the chest wall after chemo and radiation therapy (TES-2b). In contrast to TES-1, TES-2b cells are tumorigenic in immuno deficient mice and can be followed and quantified by non-invasive bioluminescence imaging after injecting the F-luc tagged cancer cells into the 4th mammary fat pad. Illumina microarray analysis revealed a 66-fold increase in CXCL14 expression in TES-2b cells over TES-1 cells, ranking it as one of the top 25 genes most differentially expressed among over 25,000 identified gene transcripts. We validated CXCL14 overexpression in TES-2b cells by real time PCR (TaqMan) (64 fold), and found a significant increase in CXCL14 protein secretion in cultured TES-2b cells (3.8 fold) by immuno-capture ELISA. To address a functional role in CXCL14 in the progression of these aggressive breast cancer cells, we stably reduced CXCL14 expression in TES-2b cells by lentiviral transduction with small interfering RNA and confirmed an 80% reduction in gene expression. CXCL14 protein production was concomitantly reduced 2.7 fold. Importantly, xenograft studies revealed a critical role of CXCL14 in the in vivo growth behavior of these breast cancer cells, as the tumor growth rate in the mammary fat pad of CXCL14 knock-down cells was significantly reduced compared to scrambled control vector treated cells. After injecting 5×105 F-luc tagged tumor cells, 4/6 mice had tumors measuring 10 mm in diameter after 11 weeks (requiring sacrifice of the animals) compared with 1/6 in the CXCL14 knock-down group. These initial results indicate a critical role of tumor cell derived CXCL14 in the in vivo survival and proliferation of these breast cancer cells. Our findings provide a basis for further analyses of CXCL14 in breast cancer progression in vivo and for detailed studies of the mechanisms through which CXCL14 may promote disease progression of highly aggressive triple-negative breast cancer. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 5251. doi:10.1158/1538-7445.AM2011-5251