Role of transcription factor SOX30 in triple-negative breast cancer metastasis and tumor immune microenvironment through the TNF/TNFR2-NF-κB-CCL20/CCR6 axis.

e13037 Background: Triple-negative breast cancer (TNBC) is more aggressive and more difficult to treat than other types of breast cancer due to tumor metastasis and lack of effective therapeutic targets. Therefore, identification of new therapeutic targets and exploration of the mechanism of cancer metastasis is of great significance to the treatment of patients with TNBC. Methods: SRY-box transcription factor 30 ( SOX30) expression was evaluated in TNBC patients by immunohistochemistry analysis. The prognostic significance of SOX30 expression was assessed by Kaplan–Meier survival analysis. MTS assays were used to assess cell proliferation. Cell migration was assessed by transwell experiments. The lung metastasis models of mice was used to evaluate metastasis of TNBC in vivo. Transcriptome sequencing was used to screen for differentially expressed genes caused by SOX30. The expression of TNFR2 was assessed by qRT-PCR, western blot and IF. ChIP-PCR and dual-luciferase reporter assays were used to explore the transcriptional regulation of TNFR2 by SOX30. Mass cytometry was used to screen for different immune cell subsets induced by SOX30. Flow cytometry was used to verify changes of tumor-associated macrophages (TAMs)in the lung metastasis models of mice. TNFR2 downstream signaling pathway NF-κB wasevaluated by western blot. The recruitment of tumor-associated macrophages by CCL20 chemokines was evaluated by ELISA and in vivo injection of CCR6 inhibitors or TNF inhibitors. Results: SOX30 was significantly upregulated in TNBC subtypes, and its high expression was unfavorable to the survival of patients. It was confirmed that SOX30 promotes metastasis of TNBC, while did not affect the cell proliferation. Transcriptomics and recovery experiment hints that SOX30 may upregulation of TNFR2 to promote the metastasis of TNBC. Luciferase reporter assays and ChIP-PCR assays further indicate that SOX30 can regulate TNFR2 at the transcriptional level. Moreover, differentially expressed genes hints that SOX30 may affect tumor immune microenvironment. Mass cytometry demonstrates that SOX30 facilitates the recruitment of TAMs in lung and further verified by flow cytometry. In addition, NF-κB signal pathway of the downstream of TNFR2 was activated by SOX30. ELISA assays indicated that CCL20 was significantly up-regulated in SOX30 overexpression samples. Blocking CCL20-CCR6 axis by CCR6 inhibitor or blocking TNF-TNFR2 axis by TNF inhibitor in vivo significantly reduced tumor metastasis and the infiltration of TAMs. Altogether, our results indicate that SOX30 promotes the metastasis of TNBC by TNF/TNFR2- NF-κB-CCL20/CCR6 axis. Conclusions: This study confirms that SOX30 promotes TNBC metastasis and reveals its underlying molecular mechanism, which provide new targets for the precision treatment of TNBC.