Nrf2 modulates the hybrid epithelial/mesenchymal phenotype and Notch signaling during collective cancer migration

Abstract

Hybrid epithelial/mesenchymal cells (E/M) are key players in aggressive cancer metastasis. A challenge is to understand how these cells, which are mostly non-existent in healthy tissue, become stable phenotypes participating collective cancer migration. The transcription factor Nrf2, which is associated with tumor progression and resistance to therapy, appears to be central to this process. Here, using a combined experimental-computational approach, we show that Nrf2 functions as a phenotypic stability factor for hybrid E/M cells by inhibiting a complete epithelial-mesenchymal transition (EMT) during collective cancer migration. We demonstrate that Nrf2 and EMT signaling are spatially coordinated near the migrating front. Computational analysis of Nrf2-EMT-Notch network and experimental modulation of Nrf2 by pharmacological treatment and CRISPR/Cas9 gene editing reveal that Nrf2 stabilizes a hybrid E/M phenotype maximally observed in the interior region immediately behind the leading edge. We further demonstrate that the Nrf2-EMT-Notch network enhances Dll4 and Jagged1 expression near the leading edge, which correlates with the formation of protruding tips and leader cells. Together, Nrf2 acts as a phenotypic stability factor in restricting complete EMT and coordinating collective cancer migration.

Long Noncoding RNA MALAT1 is Dynamically Regulated in Leader Cells during Collective Cancer Invasion

“…In agreement with previous studies, the cells migrated coherently and formed protruding tips with the leader-follower organization (Fig. 3a) 36,37 . The formation of migration tips and leader cells was clearly observed eight hours after scratching.…”

“…In agreement with previous studies, the cells migrated coherently and formed protruding tips with the leader-follower organization ( Fig. 3a ) 36, 37 The formation of migration tips and leader cells was clearly observed eight hours after scratching. In this study, the cells at the protruding tips were classified as leader cells, and the cells behind were considered as follower cells.…”

“…S8). However, the cell monolayer was less coherent compared to typical epithelia in wound healing studies 37,41 . After scratching, the cells exhibited an elongated, spindle-shaped morphology near the migrating front.…”

“…We further evaluated the relationship between MALAT1 and leader cells using a 3D tumor invasion assay 37, 39 . We formed 3D cancer spheroids with bladder cancer cells transfected with the FRET nanobiosensors.…”

Intratumoral Heterogeneity Promotes Collective Cancer Invasion through NOTCH1 Variation

“…There are several limitations of the study. In particular, the simplified computational model was not an explicit representation of the underlying signaling network [48], and the model parameters were not verified quantitatively. The computational model was only intended to illustrate the potential influence of NOTCH variation.…”