The malignancy suppression and ferroptosis facilitation of BCL6 in gastric cancer mediated by FZD7 repression are strengthened by RNF180/RhoC pathway

Background B-cell lymphoma 6 (BCL6) is a transcription repressor that plays a tumor suppressor or promoting role in various tumors. However, its function and molecular mechanism in gastric cancer (GC) remain unclear. Ferroptosis, a novel programmed cell death, is closely related to tumor development. In this research, we aimed to explore the role and mechanism of BCL6 in malignant progression and ferroptosis of gastric cancer. Methods Firstly, BCL6 was identified as an important biomarker that attenuated the proliferation and metastasis of GC through tumor microarrays and confirmed in GC cell lines. RNA sequence was performed to explore the downstream genes of BCL6. The underlying mechanisms were further investigated by ChIP, dual luciferase reporter assays and rescue experiments. Cell death, lipid peroxidation, MDA and -Fe2+ level were detected to determine the effect of BCL6 on ferroptosis and the mechanism was revealed. CHX, MG132 treatment and rescue experiments were used to explore the upstream regulatory mechanism of BCL6. Results Here we showed that BCL6 expression was significantly decreased in GC tissues, and patients with low BCL6 expression showed more malignant clinical features and poor prognosis. The upregulation of BCL6 may significantly inhibited the proliferation and metastasis of GC cells in vitro and in vivo. In addition, we found that BCL6 directly binds and transcriptionally represses Wnt receptor Frizzled 7 (FZD7) to inhibit the proliferation, metastasis of GC cells. We also found that BCL6 promoted lipid peroxidation, MDA and -Fe2+ level to facilitate ferroptosis of GC cells by FZD7/ss catenin/TP63/GPX4 pathway. Furthermore, the expression and function of BCL6 in GC were regulated by the ring finger protein 180 (RNF180)/ras homolog gene family member C (RhoC) pathway, which had been elucidated to be involved in significantly mediating the proliferation and metastasis of GC cells.

Automated summary

BCL6 expression is significantly decreased in gastric cancer tissues, and low expression is associated with malignant clinical features and poor prognosis. BCL6 inhibits the proliferation and metastasis of gastric cancer cells by directly binding and repressing the Wnt receptor FZD7 and promoting ferroptosis through the FZD7/ss catenin/TP63/GPX4 pathway. The expression and function of BCL6 in gastric cancer are regulated by the RNF180/RhoC pathway, which is involved in mediating the proliferation and metastasis of gastric cancer cells.