A Unique Signature for Cancer-Associated Fibroblasts in Melanoma Metastases

Area of Science:

• Oncology
• Cancer Biology
• Tumor Microenvironment Research

Background:

• Cancer-associated fibroblasts (CAFs) are key components of the tumor microenvironment (TME).
• Previous single-cell RNA-sequencing (scRNA-seq) studies show CAF heterogeneity across different cancer types.
• Understanding CAF diversity is crucial for targeted cancer therapies.

Purpose of the Study:

• To analyze and compare transcriptional signatures of CAFs from primary melanoma tumors and lung metastases.
• To identify distinct CAF subsets in primary versus metastatic settings.
• To investigate potential therapeutic targets within metastasis-associated CAFs.

Main Methods:

• Single-cell RNA-sequencing (scRNA-seq) of approximately 8400 CAFs and normal fibroblasts.
• Comparative analysis of CAF genetic profiles from murine melanoma primary tumors and lung metastases.
• Spatial characterization of metastasis CAFs at RNA and protein levels.
• In vitro recapitulation of identified signaling pathways.
• Analysis of human melanoma metastasis tissue sections.

Main Results:

• Distinct CAF subsets were identified in primary melanoma tumors compared to lung metastases.
• scRNA analyses revealed tumor-dependent crosstalk between neutrophils and CAFs in metastases.
• This crosstalk is mediated by SAA3 and IL1b-related signaling pathways.
• The identified neutrophil-CAF interaction was validated in vitro and observed in human melanoma metastases.
• Unique characteristics of metastasis CAFs were highlighted.

Conclusions:

• Metastasis-associated CAFs possess distinct transcriptional profiles compared to primary tumor CAFs.
• Neutrophil-CAF crosstalk, mediated by SAA3 and IL1b, is a key feature of melanoma metastasis.
• These findings suggest novel therapeutic strategies targeting CAFs in melanoma metastasis.