myCAF-derived exosomal PWAR6 accelerates CRC liver metastasis via altering glutamine availability and NK cell function in the tumor microenvironment

Abstract

Liver metastasis from colorectal cancer (CRC) is a major clinical challenge that severely affects patient survival. myofibroblastic cancer-associated fibroblasts (myCAFs) are a major component of the CRC tumor microenvironment, where they contribute to tumor progression and metastasis through exosomes. Single-cell analysis highlighted a notable increase in myCAFs in colorectal cancer liver metastases (CRLM). Exosomal sequencing identified PWAR6 as the most significantly elevated lncRNA in these metastatic tissues. In vivo and in vitro assays confirmed PWAR6's roles in CRC cell stemness, migration, and glutamine uptake. RNA pulldown, RIP, and Co-IP assays investigated the molecular mechanisms of the PWAR6/NRF2/SLC38A2 signaling axis in CRC progression, flow cytometry was used to assess NK cell activity and cytotoxicity. Clinically, higher PWAR6 expression levels are strongly associated with increased 68Ga FAPI-PET/CT SUVmax values, particularly in CRLM patients, where expression significantly exceeds that of non-LM cases and normal colon tissues. Regression analysis and survival data further support PWAR6 as a negative prognostic marker, with elevated levels correlating with worse patient outcomes. Mechanistically, PWAR6 promotes immune evasion by inhibiting NRF2 degradation through competitive binding with Keap1, thereby upregulating SLC38A2 expression, which enhances glutamine uptake in CRC cells and depletes glutamine availability for NK cells. myCAFs derived exosomes PWAR6 represents a pivotal marker for CRC liver metastasis, and its targeted inhibition with ASO-PWAR6, in combination with FAPI treatment, effectively curtails metastasis in preclinical models, offering promising therapeutic potential for clinical management.