ZBTB6 promotes breast cancer progression by inhibiting ARHGAP6 transcription and modulating the STAT3 signaling pathway.

Background: The ZBTB (zinc finger and BTB domain-containing) protein family comprises a significant class of transcription factors that interact with various corepressors and histone/protein-modifying enzymes. This interaction facilitates chromatin remodeling and the regulation of gene silencing or activation, thereby playing a crucial role in cancer progression. However, the biological effects and molecular mechanisms of ZBTB6, a member of the ZBTB family, in cancer remain unclear.

Methods: The expression levels of ZBTB6 in breast cancer (BC) were investigated through public database queries, real-time quantitative PCR (qRT‒PCR), and Western blot analysis. The effects of ZBTB6 on BC cell viability were assessed via MTT assays. Flow cytometry was utilized to analyze the cell cycle distribution and apoptosis. Additionally, cell-derived xenograft experiments were conducted to study the impact of ZBTB6 on BC growth in vivo. The relationship between ZBTB6 and the ARHGAP6 promoter was evaluated via bioinformatics predictions, chromatin immunoprecipitation (ChIP) coupled with qRT‒PCR, and luciferase reporter assays.

Results: Our study demonstrated that ZBTB6 is highly expressed in primary BC specimens and cell lines and strongly correlated with tumor grade and poor prognosis. In vitro, ZBTB6 knockdown inhibited cell viability and cell cycle progression while promoting apoptosis; conversely, ZBTB6 overexpression elicited the opposite effects. In vivo, the inhibition of ZBTB6 expression in BC cells significantly suppressed tumor growth. Furthermore, we identified ARHGAP6 as a transcriptional target downstream of ZBTB6, with ZBTB6 binding to the promoter region of ARHGAP6 to repress its transcription. Notably, ARHGAP6 can exert an inhibitory effect on tumors by attenuating STAT3 activity. Our results indicate that ZBTB6 overexpression enhances the STAT3 signaling pathway, whereas ARHGAP6 overexpression counteracts the effects of ZBTB6 overexpression in BC cells.

Conclusion: These findings suggest that ZBTB6 promotes breast cancer progression by repressing the transcription of ARHGAP6 and activating the STAT3 signaling pathway. Consequently, ZBTB6 may serve as a potential prognostic biomarker or therapeutic target for breast cancer patients.