Aristin Revilla, S. | Search bioRxiv

bioRxiv2025

Site-dependent Treg cell transcriptional reprograming in a metastatic colorectal cancer model holds prognostic significance

In colorectal cancer (CRC), tumor-infiltrating regulatory T (Treg) cells suppress anti-tumor immunity, promoting immune evasion and tumor progression. Effective therapies require selectively targeting tumor-infiltrating Treg (TI-Treg) cells while preserving systemic Treg cells, necessitating insight into their adaptations within the tumor microenvironment. Here, CRC-organoids were implanted in the liver of Foxp3eGFP mice to investigate location-specific phenotypic differences in TI-Treg cells. Tumor tissue exhibited an increased proportion of Treg cells and a decrease of effector CD4 and CD8 T cells compared to matched healthy tissue. RNA sequencing of Treg cells isolated from the spleen, primary liver tumor transplant, or metastases identified gene expression profiles previously associated with CRC-related Treg cells in patients. Location-specific differences included elevated expression of WNT-pathway genes in peritoneal TI-Treg cells compared to liver counterparts. Higher expression of genes upregulated in liver TI-Treg cells correlated with poor CRC prognosis. Splenic Treg cells from tumor-bearing mice displayed distinct transcriptional profiles from both their healthy counterparts and TI-Treg cells, suggesting they represent a distinct CD4+ population. Taken together, these findings highlight TI-Treg cells heterogeneity across different tumor sites and the distinct nature of splenic Treg cells in tumor-bearing hosts.

immunology↗

bioRxiv2024

Tumor-derived colorectal cancer organoids induce a unique Treg cell population through direct modulation of CD4+ T cell differentiation.

In colorectal cancer (CRC), increased numbers of tumor-infiltrating CD4+ regulatory T (Treg) cells correlate with tumor development and immunotherapy failure, leading to poor prognosis. However, the molecular and cellular mechanisms governing Treg recruitment, expansion, or differentiation remain unclear. Here, we developed an in vitro co-culture system to assess the capacity of CRC tumors to directly modulate Treg cell differentiation. CD4+ T cells from Foxp3eGFP mice were co-cultured with murine tumor-derived CRC organoids, resulting in a significant increase in Treg cell numbers. This induction of Treg cells was not due to increased proliferation, but rather through differentiation of CD4+ T cells in a TGF{beta}-dependent manner. Human CRC tumor organoids similarly induced Treg cells that exhibited enhanced suppressive capacity compared to TGF{beta}-induced Treg cells. RNA-sequencing analysis identified distinct transcriptional profiles between CRC organoid-induced Treg cells and TGF{beta}-induced Treg cells, with upregulation of key functional signature genes linked to CRC Treg cells in vivo. High expression of genes upregulated in CRC organoid-induced Treg cells correlates with shorter progression free interval and overall survival of CRC patients, highlighting their prognostic potential. Taken together, CRC tumor organoids drive CD4+ differentiation to Treg cells with a phenotype resembling tumor-infiltrating Treg cells. This model can be applied to both understand the molecular mechanisms by which tumors can directly modulate CD4+ T cell differentiation and identify approaches to disrupt Treg cell function and stimulate anti-tumor immunity.

immunology↗