Abstract 3019: The role of TACC3 in the progression from ductal carcinoma in situ to invasive breast cancer

Abstract

Abstract Ductal carcinoma in situ (DCIS) is a non-invasive breast cancer with the potential to become invasive/metastatic. The development of DCIS to invasive breast cancer is an important aspect of breast tumor aggressiveness, however, little is known about the genetic and molecular alterations involved in this progression. Also, analysis of molecular markers and genetic signatures of DCIS and invasive breast cancer have failed to identify transition-specific biomarkers or pathways. Hence, identifying the molecular mechanisms by which DCIS progresses to invasive breast cancer is critical for the success of diagnosis, prognosis and therapy of breast cancer. Members of the transforming acidic coiled-coil (TACC) protein family are key players in the maintenance of centrosome integrity, the regulation of microtubule assembly, and spindle stability during mitosis. TACC3 has been shown to be involved in the regulation of centrosome-microtubule dynamic networks, cell growth and differentiation, and transcription/gene expression through interactions with other molecules. Mounting evidence indicates that high levels of TACC3 may contribute to breast cancer development. Here, we investigated the significance of TACC3 in the transition of DCIS to invasive breast cancer. First, we examined the expression of TACC3 in non-tumorigenic human mammary epithelial MCF10A cells and MCF10DCIS.COM cells, which are known to form DCIS-like lesions in mice and to progress to invasive cancer, and found that the expression of TACC3 is elevated in MCF10DCIS.COM cells compared to MCF10A cells. By analyzing tissue microarray data, we found that expression of TACC3 gradually increased from normal breast to DCIS, and further increased in invasive breast cancer. In addition, ectopic expression of TACC3 in MCF10DCIS.COM cells promoted cell proliferation, migratory and invasive capabilities as well as the epithelial-mesenchymal transition (EMT)-like phenotype. Moreover, MCF10DCIS.COM cells stably expressing TACC3 exhibited increased expression of stemness markers. Interestingly, a small molecule inhibitor of TACC3, KHS101 treatment in MCF10DCIS.COM cells significantly suppressed cell proliferation and the PI3K/AKT signaling pathway while having little effect on MCF10A cells. Our findings, therefore, suggest that TACC3 may play an important role in the progression from DCIS to invasive breast cancer and that targeting TACC3 could be a promising new therapeutic strategy for DCIS patients. Citation Format: Loredana Campo, Maya Mathew, Eun-Kyoung breuer, William Small. The role of TACC3 in the progression from ductal carcinoma in situ to invasive breast cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 3019. doi:10.1158/1538-7445.AM2017-3019