Abstract 31: Li-Fraumeni syndrome patient-derived LFS50 progression cell series: An experimental model for breast cancer prevention research

Background: Invasive cancer can be prevented or delayed in healthy but high-risk individuals; however, its prevention is a challenge partly due to (i) the lack of preclinical models that represent high-risk individuals in mechanistic in vitro studies and (ii) the difficulty in rational selection of novel targets and agents with a favorable risk to benefit ratio. Preclinical cell line models developed from high-risk, non-malignant breast tissue of women genetically predisposed to breast cancer can be a renewable resource for in vitro exploratory and cancer prevention studies. Toward this goal, contralateral breast tissue of a Li-Fraumeni syndrome (LFS) patient (patient 50 with a germline TP53 [M133T] mutation) undergoing breast cancer surgery was used to generate human mammary epithelial (HME) LFS progression series. This HME LFS50 series comprises of distinct pre-immortal (HME50), spontaneously immortalized (HME50-5E), hTERT-immortalized (HME50hTERT), HrasV12-transformed/pre-invasive (HME50hTR) and tumorigenic (HMET) cell lines and can be used to model different stages of breast cancer. Methods and Results: We have characterized the HME LFS50 cell lines in vitro as monolayers, 3D cultures, and by bioinformatics approach. Gene expression signatures of LFS50 series cells were profiled using HG-U133_Plus_2 Affymetrix chips, principal component analyses (PCA), and hierarchical clustering. Using the TNBCtype subtyping tool, we aligned LFS50 cell lines to triple negative breast cancer (TNBC) signatures that classified each of LFS50 cell lines as a different TNBC subtype model, suggesting that each HME LFS50 cell line would respond differentially to different chemotherapeutic agents. Furthermore, using Ingenuity Pathway Analysis (IPATM) we identified the most differentially expressed genes and canonical pathways that also support the TNBC subtyping results and provide rational targeting for chemoprevention studies. We determined the effects of p53 rescue agents (e.g., PRIMA-1) and chemopreventive agents such as epigallocatechin-3-galate and resveratrol, and found that tumorigenic HMET cells were most sensitive to these agents as compared to non-malignant HME50-hTERT and MCF10A controls. In addition, anchorage-independent growth could be prevented by chemopreventive agents for the HME50hTR pre-invasive cells. Finally, as a proof-of-principle for drug targeting, treatment of the LFS50 series with PRIMA-1 using 3D cultures resulted in a reduction in acini size of th