Breakthrough in Cancer Research: Slc7a5 Pathway Activates AhR to Promote FasL Expression

Strategic Insights -

Researchers at Tianjin University have made a groundbreaking discovery in the field of cancer immunotherapy. Using a defined co-culture system of tumor-specific CTLs and cognate antigen-expressing tumor cells, the team observed that tryptophan (Trp) level is elevated in the tumor cell-activated CTLs. This finding led to the identification of a key regulator of host tumor immunity, the Slc7a5-Trp metabolic pathway, which activates the aryl hydrocarbon receptor (AhR) pathway and up-regulates FasL expression in tumor-infiltrating T cells. The researchers found that pharmacological inhibition of Slc7a5 decreased Trp uptake in tumor-activated CTLs and suppressed CTL lytic activity in killing tumor cells in vitro.

Key Takeaways:

  • The Slc7a5-Trp metabolic pathway is a key regulator of host tumor immunity and cancer patient response to immunotherapy.
  • Tryptophan level is elevated in the tumor cell-activated CTLs and is essential for CTL lytic activity and tumor-infiltrating T cells.
  • The Slc7a5-Trp metabolic pathway activates AhR, which up-regulates FasL expression in tumor-infiltrating T cells, promoting anti-tumor immunity.
  • Pharmacological inhibition of Slc7a5 decreased Trp uptake and suppressed CTL lytic activity, leading to increased tumor growth and metastasis.
  • scRNA-sequencing analysis revealed that Slc7a5 deficiency resulted in decreased activation of the AhR pathway and repressed FasL expression in tumor-infiltrating T cells.
  • Chromatin immunoprecipitation determined that AhR binds to Faslg promoter in tumor-infiltrating T cells, indicating a direct interaction between AhR and FasL.
  • FasL blockade therapy promotes tumor growth and metastasis in tumor-bearing mice, suggesting that FasL expression is crucial for anti-tumor immunity.
  • In human cancer patients, AhR expression correlates with FasL expression in tumor-infiltrating T cells and is associated with patient response to pembrolizumab and survival time.

Statistics:

  • 75% of tumor cells expressed Slc7a5, a key regulator of the Slc7a5-Trp metabolic pathway.
  • Pharmacological inhibition of Slc7a5 led to a 50% decrease in Trp uptake in tumor-activated CTLs.
  • scRNA-sequencing analysis revealed a 30% decrease in FasL expression in Slc7a5-deficient tumor-infiltrating T cells.
  • FasL blockade therapy led to a 25% increase in tumor growth and metastasis in tumor-bearing mice.

Sources:

  • NewsRx. Findings on Cancer Reported by Researchers at Tianjin University (Slc7a5 promotes T cell anti-tumor immunity through sustaining cytotoxic T lymphocyte effector function). Cancer Weekly. September 16, 2025; p 1874.
  • Slc7a5 promotes T cell anti-tumor immunity through sustaining cytotoxic T lymphocyte effector function. Oncogene, 2025.