Abstract LB-114: Using molecular imaging to identify modulators of breast cancer metastasis

Abstract

Abstract Metastasis occurs through a sequence of stages involving dissociation of cells from the primary tumor, local invasion and migration through the basement membrane and into the circulation, survival in the circulation, extravasation into foreign organs, tumor dormancy, and finally tumor growth in the new organ. Our laboratory has characterized several preclinical “Human In Mouse” (HIM) breast cancer models for their ability to metastasize from the humanized mammary gland to foreign organs including lymph node, lung, and/or bone. We believe this model of breast cancer metastasis more accurately reflects the biology of human breast metastasis than do currently used methods of introducing cancer cells directly into the mouse circulation. One HIM line, HIM3, is able to grow in cell culture and was characterized as triple negative and wild type for p53. HIM3 was engineered to express a fusion protein for Click Beetle Red Luciferase (CBRluc) and mCherry, and this bioluminescent HIM3 line was further transduced with control lentivirus (HIM3p53WT) or lentivirus encoding shRNA targeting p53 (HIM3p53KD). After engraftment into the humanized mammary fat pad of immune compromised mice, bioluminescence imaging (BLI) was employed to detect metastasis. Preliminary data revealed that disruption of the p53 pathway increased tumor growth and decreased latency to metastasis. In addition, loss of p53 altered the homing of breast tumor cells to secondary sites. Breast tumor cells from the mammary gland as well as secondary metastatic sites (lymph node (LN), lung, liver, and bone) were harvested for RNA isolation and for re-engraftment into the mammary glands of recipient humanized mice. My is goal to enrich for tumor cells that preferentially home to lung, bone, and liver. RNA isolated from these tumors will be subjected to RNA-seq in order to identify genomic and epigenetic changes responsible for organ-specific homing. I have already observed that serial passaging is generating sub populations of tumors that metastasize more quickly out of the mammary gland to populate their preferred organ. I hypothesize that enrichment for metastatic subpopulations will reveal transcriptional profiles that are unique from the primary-site populations from which they derive. Moreover, I hypothesize that human breast cancer cells that home to lung will exhibit diverse transcriptional profiles compared to those that home to bone, and that loss of a functional p53 pathway will lead to the transcriptional upregulation of genes responsible for promoting EMT and metastasis. Functional assessment of the gene products encoded by these differentially expressed genes is expected to add important new information about breast cancer metastasis and lead to future reductions in breast cancer mortality. 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 LB-114. doi:1538-7445.AM2012-LB-114