Abstract 93: Defining the roles of COIL and WIPI1 in breast cancer metastasis

Abstract

Abstract Metastasis of cancerous cells to distant sites is the major cause of death from breast cancer. In a previous study, we performed aCGH on breast invasive duct carcinoma samples with and without lymph node metastases and identified regions of genomic amplification that are associated with lymph node metastasis. These were subsequently validated by q-PCR. Within the 17q22-24 region, we have identified four genes likely to contribute to metastasis based on published data: COIL, WIPI1, TMEM100, and SLC16A6. We are using RNAi and ectopic over-expression to characterize these genes with in vitro functional assays for proliferation, migration, invasion, and survival. We used qRT-PCR analysis on a panel of seven breast cancer cell lines of varying invasiveness: MDA-MB-157, MDA-MB-231, MDA-MB-468, BT-549, CAMA-1, HS578T, MCF-7, and SKBR-3. We identified that WIPI1 and COIL were expressed in the majority. WIPI1 is up-regulated in a variety of tumor cells; studies suggest WIPI1 can activate autophagy by suppressing TORC1. Autophagy can inhibit cancer by maintaining genome stability via disposing of damaged mitochondria and peroxisomes. In clinical data obtained from 298 breast cancer patients, we observed high expression of WIPI1 to be associated with higher survival and lower breast cancer relapse. Alternatively, autophagy can also provide a survival mechanism for tumors with restricted blood supply and resistance to chemotherapy. This is in agreement with our observation of high WIPI1 protein expression in highly invasive breast cancer cell lines. We are over-expressing WIPI1 in SKBR-3 and knocking it down in BT-549 in vitro. WIPI1 could help determine the role of autophagy in tumor initiation processes such as proliferation and invasion, and in maintenance of tumor cells following therapy. COIL is found in a diffuse nucleoplasmic pool and in Cajal bodies (CBs). The role of diffuse COIL is still unclear, but CBs, involved in the formation of macromolecular complexes and found more in cells with high transcriptional activity, require COIL for proper formation and localization. We observed high expression of COIL protein in cell lines with higher proliferation index, noticeably in ER positive cell lines such as CAMA1 and absence in a non-tumorogenic cell line MCF10A. We are investigating the association of COIL with proliferation, invasion and migration abilities by over-expression and knockdown of the COIL protein in MDA231 and MCF7 breast cancer cells. We found from clinical data obtained from 245 breast cancer patients that high expression of COIL resulted in lower survival and a higher risk of relapse. This suggests that COIL may be a potential therapeutic target. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 93. doi:1538-7445.AM2012-93