ELK3-ID4 axis governs the metastatic features of triple negative breast cancer

Cancer cell metastasis is a multistep process, and the mechanism underlying extravasation remains unclear. ELK3 is a transcription factor that plays a crucial role in regulating various cellular processes, including cancer metastasis. Based on the finding that ELK3 promotes the metastasis of triple-negative breast cancer (TNBC), we investigated whether ELK3 regulates the extravasation of TNBC by forming the ELK3-ID4 axis. ID4 functions as a transcriptional regulator that interacts with other transcription factors, inhibiting their activity and subsequently influencing various biological processes associated with cell differentiation, survival, growth, and metastasis.

We assessed the correlation between the expression of ELK3 and that of ID4 in TNBCs using bioinformatics analyses, QRT-PCR, western blot analysis, luciferase reporter assays, and chromatin immunoprecipitation. Migration, adhesion, invasion, and lung metastasis assays were employed to determine whether the ELK3-ID4 axis regulates the metastatic features of TNBC.

We found that ELK3 binds directly to a binding motif close to the ID4 promoter to repress promoter activity. The expression of E-cadherin in TNBC was regulated by the ELK3-ID4 axis. In vitro and in vivo analyses showed that inhibiting ID4 expression in ELK3-knockdown MDA-MB-231 (ELK3KD) cells restored the ability to extravasate and metastasize.

The results indicate that the ELK3 regulates ID4 promoter activity, and that the ELK3-ID4 axis regulates the metastatic characteristics of TNBC cells. Additionally, the data suggest that the ELK3-ID4 axis regulates metastasis of TNBCs by modulating expression of E-cadherin.