Microbiome Dysbiosis, Neutrophil Recruitment and Mesenchymal Transition of Mesothelial Cells Promotes Peritoneal Metastasis of Colorectal Cancer

Immunology Biochemistry Life Sciences Cell Biology Oncology Gastroenterology Medicine
microbiome dysbiosis neutrophil recruitment mesothelial cells mesenchymal transition colorectal cancer peritoneal metastasis tumor microenvironment

Background Introduction

Colorectal cancer (CRC) is one of the most prevalent malignancies worldwide, with high incidence and mortality rates. According to statistics, approximately 1.87 million new cases of CRC were diagnosed globally in 2020, resulting in 915,000 deaths. Peritoneal metastasis (PM) is a common metastatic pathway of CRC, with about 5% of patients presenting with PM at the time of initial surgery. The prognosis for PM is extremely poor, with a median survival of only 5 months in untreated patients. Currently, cytoreductive surgery combined with hyperthermic intraperitoneal chemotherapy is the only potentially curative treatment, but the recurrence rate remains as high as 50%-90%. Therefore, there is an urgent need to deeply understand the pathobiology of PM and identify new therapeutic targets.

In recent years, the rapid development of single-cell RNA sequencing (scRNA-seq) technology has provided unprecedented opportunities to study the heterogeneity of the tumor microenvironment (TME). This technology allows researchers to comprehensively analyze the cellular composition of tumors and their metastatic sites, revealing key mechanisms of tumor progression and metastasis. This study aims to explore the molecular mechanisms of PM in CRC using scRNA-seq technology combined with functional experiments, with a particular focus on the roles of microbiome dysbiosis, neutrophil recruitment, and mesenchymal transition of mesothelial cells.

Source of the Paper

This paper was jointly completed by research teams from Fudan University Shanghai Cancer Center, Peking University, City of Hope Comprehensive Cancer Center, and other institutions. The main authors include Qingguo Li, Yiwei Xiao, Lingyu Han, and others. The paper was published in March 2025 in the journal Nature Cancer, titled “Microbiome dysbiosis, neutrophil recruitment and mesenchymal transition of mesothelial cells promotes peritoneal metastasis of colorectal cancer.”

Research Process and Results

1. Single-cell RNA Sequencing Reveals the Cellular Atlas of CRC and PM

The research team first performed single-cell RNA sequencing on 12 treatment-naive CRC patients, analyzing a total of 48 matched samples, including primary CRC, peritoneal metastases, liver metastases, and adjacent normal tissues. Using 10x Genomics technology, the team successfully obtained high-quality transcriptomic data from 316,069 single cells and constructed a single-cell atlas of CRC and PM.

The cells were classified into eight major categories: epithelial cells, T/NK lymphocytes, B cells, plasma cells, myeloid cells, neutrophils, mast cells, and stromal cells. Further subclustering revealed multiple cell subtypes, including various subtypes of neutrophils, macrophages, and fibroblasts. Comparative analysis showed a significant increase in stromal cells in PM, while mast cells and neutrophils were relatively reduced.

2. Differential Distribution of Neutrophils in CRC and PM

The research team found that neutrophils were significantly enriched in the CRC microenvironment but significantly reduced in PM. Through receptor-ligand interaction network analysis, the team revealed the primary mechanism of neutrophil recruitment in CRC: epithelial cells, endothelial cells, and fibroblasts express chemokines such as CXCL1/2/3/6/8 to attract CXCR2/4+ neutrophils. Additionally, neutrophils in the CRC microenvironment highly express NLPR3, suggesting their recruitment may be triggered by sensing bacterial infections.

Using fluorescence in situ hybridization (FISH) technology, the team confirmed the presence of substantial bacterial infiltration in CRC tissues, with intestinal microbiota dysbiosis closely related to neutrophil recruitment. Further functional experiments demonstrated that neutrophils in CRC exhibit a protumor phenotype, while those in PM exhibit an antitumor phenotype.

3. Role of Mesothelial-to-Mesenchymal Transition in PM

The research team found that malignant cells in PM exhibit significant mesenchymal transition characteristics, closely associated with mesothelial-to-mesenchymal transition (MMT). Through scRNA-seq and functional experiments, the team confirmed that mesothelial cells transform into fibroblasts during PM, promoting tumor cell invasion and metastasis.

Additionally, the team discovered that MMT is closely related to direct interactions between mesothelial cells and tumor cells. Co-culture experiments confirmed the co-transition phenomenon between mesothelial cells and tumor cells, revealing its underlying molecular mechanisms.

4. Potential of Anti-Mesothelin Antibody in Inhibiting PM

Based on the critical role of MMT in PM, the research team explored the therapeutic potential of anti-mesothelin antibody (anti-MSLN). Through in vitro and in vivo experiments, the team confirmed that anti-MSLN significantly inhibits MMT and effectively suppresses PM progression.

Research Conclusions and Significance

This study, through scRNA-seq technology combined with functional experiments, revealed the molecular mechanisms of PM in CRC, particularly the key roles of microbiome dysbiosis, neutrophil recruitment, and MMT. The results indicate that neutrophils in CRC exhibit a protumor phenotype, while those in PM exhibit an antitumor phenotype. Additionally, MMT plays a crucial role in PM, and anti-MSLN can effectively inhibit PM progression.

The scientific value of this study lies in its in-depth analysis of the molecular mechanisms of PM in CRC, providing a theoretical basis for developing new treatment strategies. Furthermore, the study proposes potential strategies for tumor therapy through engineered neutrophils and targeting MMT, offering significant clinical application prospects.

Research Highlights

  1. Single-cell RNA Sequencing Reveals the Cellular Atlas of CRC and PM: Through large-scale scRNA-seq, the research team constructed a single-cell atlas of CRC and PM, revealing the heterogeneity of the TME.
  2. Differential Distribution of Neutrophils in CRC and PM: The team found that neutrophils in CRC exhibit a protumor phenotype, while those in PM exhibit an antitumor phenotype, highlighting the dual role of neutrophils in tumor progression.
  3. Key Role of MMT in PM: The team confirmed that mesothelial cells transform into fibroblasts during PM, promoting tumor cell invasion and metastasis, providing a new perspective on the mechanisms of PM.
  4. Potential of Anti-MSLN in Inhibiting PM: Through in vitro and in vivo experiments, the team confirmed that anti-MSLN significantly inhibits PM progression, providing experimental evidence for developing new treatment strategies.

Other Valuable Information

This study also found that intestinal microbiota dysbiosis in CRC is closely related to neutrophil recruitment, suggesting the important role of microbiota in tumor progression. Additionally, the team proposed a potential strategy for tumor therapy through engineered neutrophils, offering new insights into tumor immunotherapy.

Through multi-level experimental design and in-depth data analysis, this study revealed the molecular mechanisms of PM in CRC, providing important theoretical and experimental support for developing new treatment strategies.