LOXL1 and LOXL4 are novel target genes of the Zn-bound form of ZEB1 and play a crucial role in the acceleration of invasive events in triple-negative breast cancer cells.

BACKGROUND

EMT has been proposed to be a crucial early event in cancer metastasis. EMT is rigidly regulated by the action of several EMT-core transcription factors, particularly ZEB1. We previously revealed an unusual role of ZEB1 in the S100A8/A9-mediated metastasis in breast cancer cells that expressed ZEB1 at a significant level and showed that the ZEB1 was activated on the MCAM-downstream pathway upon S100A8/A9 binding. ZEB1 is well known to require Zn for its activation based on the presence of several Zn-finger motifs in the transcription factor. However, how Zn-binding works on the pleiotropic role of ZEB1 through cancer progression has not been fully elucidated.

METHODS

We established the engineered cells, MDA-MB-231 MutZEB1 (MDA-MutZEB1), that stably express MutZEB1 (ΔZn). The cells were then evaluated for their invasion activities. Finally, an RNA-Seq analysis was performed to compare the gene alteration profiles of the established cells comprehensively.

RESULTS

MDA-MutZEB1 showed a significant loss of the EMT, ultimately stalling the invasion. Inclusive analysis of the transcription changes after the expression of MutZEB1 (ΔZn) in MDA-MB-231 cells revealed the significant downregulation of LOX family genes, which are known to play a critical role in cancer metastasis. We found that LOXL1 and LOXL4 remarkably enhanced cancer invasiveness among the LOX family genes with altered expression.

CONCLUSIONS

These findings indicate that ZEB1 potentiates Zn-mediated transcription of plural EMT-relevant factors, including LOXL1 and LOXL4, whose upregulation plays a critical role in the invasive dissemination of breast cancer cells.