Triple-negative breast cancer metastasis involves complex epithelial-mesenchymal transition dynamics and requires vimentin

Abstract

Triple-negative breast cancer (TNBC) is an aggressive subtype associated with early metastatic recurrence and worse patient outcomes. TNBC tumors express molecular markers of the epithelial-mesenchymal transition (EMT), but its requirement during spontaneous TNBC metastasis in vivo remains incompletely understood. We demonstrated that spontaneous TNBC tumors from a genetically engineered mouse model (GEMM), multiple patient-derived xenografts, and archival patient samples exhibited large populations in vivo of hybrid E/M cells that lead invasion ex vivo while expressing both epithelial and mesenchymal characteristics. The mesenchymal marker vimentin promoted invasion and repressed metastatic outgrowth. We next tested the requirement for five EMT transcription factors and observed distinct patterns of utilization during invasion and colony formation. These differences suggested a sequential activation of multiple EMT molecular programs during the metastatic cascade. Consistent with this model, our longitudinal single-cell RNA analysis detected three different EMT-related molecular patterns. We observed cancer cells progressing from epithelial to hybrid E/M and strongly mesenchymal patterns during invasion and from epithelial to a hybrid E/M pattern during colony formation. We next investigated the relative epithelial versus mesenchymal state of cancer cells in both GEMM and patient metastases. In both contexts, we observed heterogeneity between and within metastases in the same individual. We observed a complex spectrum of epithelial, hybrid E/M, and mesenchymal cell states within metastases, suggesting that there are multiple successful molecular strategies for distant organ colonization. Together, our results demonstrate an important and complex role for EMT programs during TNBC metastasis.

Recreating heterogeneity of bladder cancer microenvironment to study its recurrences and progression

“…A similar observation can be made on the epithelial-to-mesenchymal transition, whereas it constitutes a wide spectrum and cancer cells that present intermediary phenotype might be more metastatic (21)(22)(23). Some of those works have relied on the use of engineered experimental 3D models to investigate heterogeneity in a context of a heterogeneous population (21,22). Therefore, given the identified cell subpopulations, a logical next step would be to explore their actual contribution to BCa progression and resistance to therapeutics strategies in more advanced experimental models.…”

“…Importantly, implication of EZH2 in tumor progression is not new and has been suggested in numerous tumor types from breast to prostate cancer and it can act as either as a tumor suppressor or as an oncogene (20). A similar observation can be made on the epithelial-to-mesenchymal transition, whereas it constitutes a wide spectrum and cancer cells that present intermediary phenotype might be more metastatic (21)(22)(23). Some of those works have relied on the use of engineered experimental 3D models to investigate heterogeneity in a context of a heterogeneous population (21,22).…”

“…In fact, it might be the best method to account for the stromal cell heterogeneities, and as we have previously demonstrated, the addition of CAF allows to establish a BCa-like tumor stroma that can triggers partial EMT in the epithelial compartment (32). In addition, all those 3D methods are compatible with omics assays, including scRNA-seq (22), meaning that it would be possible to see if the heterogeneity observed by Wang et al is maintained in these in vitro models. Overall, a combination of several such models is likely key in testing clinically relevant parameters, such as cell invasion or drug resistance, for targets identified in studies similar to the one presented by Wang et al in a physiologically relevant setting.…”

Stabilization of E-cadherin adhesions by COX-2/GSK3β signaling is a targetable pathway in metastatic breast cancer

“…In addition, it is becoming more evident that cancer cell dissemination may not require complete EMT but rather fluid transitions between EM phenotypes or hybrid states, termed EM plasticity (EMP) (8 , 9, 10). Thus, it has been shown that E-cadherin expression can contribute to collective cell migration, establishment of metastases, chemotherapy resistance, and cancer cell survival under hypoxia (8,(11)(12)(13)(14)(15). Furthermore, a recent report confirmed that not only is E-cadherin expressed on cluster circulating tumor cells (cCTC), which are highly metastatic and predict poor outcome (16,17), but is even more abundant than EpCAM, the traditional epithelial marker for CTCs (18).…”

Molecular insights into triple‐negative breast cancer metastasis: Epithelial– mesenchymal transition

“…“These cancers often return within three years of diagnosis, and treatments used for other breast cancers do not typically work for triple‐negative [breast cancer],” said Andrew J. Ewald, PhD, the Virginia DeAcetis Professor in Basic Cancer Research, director of the Department of Cell Biology, and coleader of the Cancer Invasion and Metastases Program at the Sidney Kimmel Cancer Center at Johns Hopkins University School of Medicine, Baltimore, Maryland, in a news release accompanying a study published in Science Translational Medicine 1,2 …”