Abstract 3622: Characterizing the metastatic potential and clonal dynamics of invasive subpopulations in TNBC cells in response to chemotherapy

Abstract

Abstract Triple negative breast cancer (TNBC) is one of the deadliest forms of breast cancer and is characterized by its high rates of metastasis, significant intra-tumor heterogeneity and lack of hormonal treatments. Through utilization of a novel genetic cell tracking technology, ClonMapper, we identify and characterize the origins of invasive subpopulations. Genetic barcodes are stably integrated into HCC1806 cells to generate starting parental populations of ~1000 unique barcoded cells. Invasive barcoded subpopulations were selected by migration through transwell assays for 24 hours and then collected for expansion. Clonal abundance sequencing across all replicates showed a >8-fold decrease in the number of unique barcodes. Similarity was quantified using the Bray-Curtis and Cosine similarity indexes. 5 out of 8 replicates shared the same lineages, where more than 50% of the replicates were composed of the same 9 unique barcodes thus indicating the pre-existence of invasive clones. Following cell subpopulation isolation, we observed that isolated subpopulations display faster growth rates than parental populations. A scratch assay verified that the 5 similar invasive subpopulations displayed elevated migration rates in this 2D migration format (invasive populations vs parental population, n= 6). Separate transwell assays also confirmed the 3-dimensional migration rates of isolated subpopulations. Parental HCC1806 and invasive subpopulations were treated with doxorubicin, cisplatin, paclitaxel and 5-flourouracil (5-FU) at their respective LD50 for 48 hours then allowed to recover to confluency before assessment by scratch assay. We observed that paclitaxel significantly decreased the migration rate, but that both doxorubicin and 5-FU resistant cells had a significantly higher migration rate (chemoresistant populations vs parental population, n=5) indicating that these drugs select for more migratory populations. Future studies will elucidate whether invasive clones are pre-existing or de novo and determine the effect of chemotherapeutics on these populations. Citation Format: Carolina De Santiago, Amy Brock. Characterizing the metastatic potential and clonal dynamics of invasive subpopulations in TNBC cells in response to chemotherapy. [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 3622.