Identification of fibroblast subpopulations facilitating to chemotherapy resistance in metastasis of ovarian cancer

Ovarian cancer, currently the deadliest gynecological malignancy, remains a challenging therapeutic issue due to chemotherapy resistance leading to tumor relapse. Chemoresistance in ovarian cancer is associated with various factors, and the role and mechanisms of cancer-associated fibroblasts (CAFs) in this process remain poorly understood. In this study, we analyzed single-cell RNA sequencing data from pre- and post-chemotherapy ovarian cancer samples to examine and compare the differences in tumor stromal cell composition. We found that the proportion of tumor-associated fibroblasts in the post-chemotherapy tumor microenvironment was significantly upregulated. Further analysis of fibroblast subpopulations revealed that chemotherapy altered the subtyping and transcriptional expression patterns of ovarian cancer fibroblasts. Through the analysis of cell composition, transcriptional expression, tissue metastasis, and functional state differences of fibroblast subpopulations before and after chemotherapy, we identified three fibroblast subpopulations with the potential to promote chemoresistance and metastasis in ovarian cancer: CCL3 ⁺ fibroblasts, MGP ⁺ fibroblasts, and MMP1 ⁺ fibroblasts. The CCL3 ⁺ and MGP ⁺ fibroblast subpopulations were upregulated in metastatic omental tissues after chemotherapy, while the MMP1 ⁺ fibroblast subpopulation was upregulated in metastatic peritoneal tissues. Differential gene expression analyses showed that CCL3 ⁺ and MGP ⁺ fibroblasts upregulated several cytokines promoting cell growth and angiogenesis, while MMP1 ⁺ fibroblasts upregulated cytokines mediating immune suppression. Moreover, secretory factors such as CCL3, MGP, MMP1, PTX3, GSN, and MMP3, which promote tumor growth and metastasis, were highly expressed in these upregulated post-chemotherapy tumor-associated fibroblasts. Pathway enrichment analysis revealed that PI3K-Akt, MAPK, TNF, NFκB, and IL-17 signaling pathways were significantly activated in these macrophage subpopulations. Finally, immunofluorescence staining of omental and peritoneal metastatic tissues from ovarian cancer patients confirmed the post-chemotherapy emergence of the CCL3 ⁺ , MGP ⁺ , and MMP1 ⁺ fibroblast subpopulations. These findings contribute to understanding the role and mechanisms of fibroblasts in ovarian cancer chemoresistance and may aid in developing therapeutic strategies targeting fibroblasts for overcoming chemoresistance in ovarian cancer.