Formononetin enhances cisplatin chemotherapy sensitivity in osteosarcoma by inducing ferroptosis and reconstructing the immune microenvironment.

BACKGROUND

Osteosarcoma is a rare malignant tumor originating from bone tissue. Despite advancements in neoadjuvant chemotherapy, the 5-year survival rate for osteosarcoma patients has plateaued around 60 % for the past fifty years, primarily due to the development of chemo-insensitivity. Cisplatin, a cornerstone in current treatment regimens, still has a low response rate in osteosarcoma patients, highlighting the need for strategies to enhance cisplatin sensitivity.

PURPOSE: The purpose of this study is to explore the effects of formononetin, a bioactive compound, in sensitizing osteosarcoma cells to cisplatin.

STUDY

DESIGN

We utilized PDX models of osteosarcoma to evaluate the combined therapeutic effect of formononetin and cisplatin. Single-cell RNA sequencing and single-cell ATAC sequencing were performed on tumor tissues from these models to provide a detailed molecular profile of the treatment effects.

METHODS

PDX models of osteosarcoma were established, followed by treatment with formononetin and cisplatin. A total of 7216 human-derived osteosarcoma cells and 89,558 mouse-derived cells were analyzed to assess their role in cisplatin sensitivity and tumor immune microenvironment changes.

RESULTS

Our findings demonstrated that cisplatin insensitivity in osteosarcoma is strongly linked to ferroptosis. Formononetin sensitized osteosarcoma cells to cisplatin by inhibiting MAZ/GPX4 axis and inducing ferroptosis. Additionally, formononetin increased NK cell infiltration and immune activity, while reducing the infiltration of exhausted Cd8+ T cells and tumor-associated neutrophils, thereby reprogramming the tumor immune microenvironment and further enhancing cisplatin sensitivity.

CONCLUSION

This study is the first to demonstrate that formononetin can enhance cisplatin sensitivity in osteosarcoma. By using osteosarcoma PDX models and performing comprehensive single-cell sequencing analyses, we identified formononetin as a promising sensitizer for cisplatin treatment. Our findings offer new therapeutic insights and mechanistic understanding that could help overcome cisplatin insensitivity in osteosarcoma and potentially improve patient outcomes.