CAFs-Derived Lactate Drives Oxaliplatin Resistance via ANTXR1 in CRC

Study Background and Research Question

Colorectal cancer (CRC) remains one of the leading causes of cancer mortality worldwide, with oxaliplatin-based chemotherapy serving as a cornerstone for both metastatic and adjuvant treatment. Despite advances, a significant proportion of CRC patients—up to 40%—demonstrate primary or acquired resistance to oxaliplatin, limiting long-term therapeutic success. Cancer stem cells (CSCs) are increasingly recognized for their roles in chemoresistance and tumor relapse, but the tumor microenvironment's contribution to this phenomenon has not been fully understood. The reference study, He et al., Cancer Letters (2025), investigates the molecular mechanisms by which cancer-associated fibroblasts (CAFs) influence oxaliplatin resistance in CRC, with a focus on the metabolic interplay and epigenetic modifications that sustain cancer stemness.

Key Innovation from the Reference Study

The principal innovation of this work lies in elucidating a metabolite-driven, epigenetic regulatory axis: CAFs exhibiting heightened glycolytic activity secrete increased lactate, which in turn induces both transcriptional and post-translational modifications of ANTXR1 in CRC cells via histone and protein lactylation. Specifically, lactylation at lysine 453 of ANTXR1 stabilizes the protein and activates downstream signaling pathways associated with stemness and therapy resistance. This mechanistic insight connects stromal-cancer cell crosstalk to the emergence of drug-resistant, stem-like cancer phenotypes, providing a clear molecular target for intervention.

Methods and Experimental Design Insights

The study employed a comprehensive range of in vitro and in vivo experimental approaches:

• Co-culture systems and conditioned medium assays to model CAF-CRC cell metabolic interactions.
• Biochemical quantification of lactate production and uptake.
• Chromatin immunoprecipitation (ChIP) and mass spectrometry to detect histone and protein lactylation, focusing on ANTXR1 and its K453 residue.
• CRISPR/Cas9-mediated gene editing and pharmacological inhibition to dissect the roles of lactate transport, ANTXR1 expression, and downstream pathways (RhoC/ROCK1/SMAD5).
• Flow cytometry and immunostaining for established cancer stem cell markers (LGR5, CD133, CD44).
• Assessment of chemosensitivity in vitro and in patient- or cell-derived xenograft mouse models, with quantification of tumor growth and response to oxaliplatin.

These methods collectively enabled the authors to rigorously track the source and impact of lactate within the tumor microenvironment and to link molecular changes to functional treatment outcomes.

Core Findings and Why They Matter

Several interconnected findings emerged from this study:

• Metabolic reprogramming of CAFs: A subset of CAFs in CRC tumors display upregulated glycolysis, leading to elevated lactate secretion.
• Lactate-induced ANTXR1 regulation: Lactate from CAFs promotes both the transcription of ANTXR1 via histone lactylation and post-translational modification of ANTXR1 at lysine 453 (K453la) in CRC cells.
• Activation of stemness and drug resistance pathways: Lactylated ANTXR1 is stabilized, leading to activation of the RhoC/ROCK1/SMAD5 signaling cascade, which in turn sustains cancer stem cell properties and increases resistance to oxaliplatin.
• Clinical correlations: High ANTXR1 and K453la levels correlate with oxaliplatin resistance and poor prognosis in CRC patient samples (He et al., 2025).
• Therapeutic implications: Inhibition of lactate shuttling between CAFs and tumor cells, either genetically or pharmacologically, restores oxaliplatin sensitivity both in vitro and in xenograft models.

These findings collectively highlight how tumor-stromal metabolic cooperation can directly reprogram cancer cell epigenetics and drive clinically relevant drug resistance. By linking CAF-derived metabolites to specific, targetable modifications within cancer cells, the study opens new avenues for improving chemotherapy outcomes in CRC.

Comparison with Existing Internal Articles

While this reference study focuses on the tumor microenvironment's role in chemoresistance, several internal articles provide practical context for molecular workflows relevant to these findings:

• Optimizing Cell-Based Assays with DNase I (RNase-free) emphasizes the importance of precise DNA removal in workflows such as RT-PCR and in vitro transcription, which are crucial for accurate quantification of gene expression and stem cell marker analysis in experimental oncology.
• DNase I (RNase-free): Precision DNA Removal in RNA Extraction highlights the necessity of removing genomic DNA to ensure the reliability of RNA-based assays, which underpins many of the methods used in the reference study, such as transcriptomic profiling of ANTXR1 and stemness markers.
• DNase I (RNase-free): Endonuclease for Precise DNA Removal provides insights into best practices for using ribonuclease-free DNase I in advanced molecular biology protocols—a consideration when designing workflows that interrogate epigenetic changes and gene regulation in cancer research.

Together, these internal resources bridge protocol optimization with the mechanistic insights described in the reference study, underscoring the importance of robust sample preparation for sensitive detection of molecular events driving chemoresistance.

Limitations and Transferability

Despite the depth of mechanistic investigation, certain limitations should be noted:

• Heterogeneity of CAFs: The study identifies a glycolytic subset of CAFs, but tumor stroma is highly heterogeneous. Further research is needed to determine whether similar mechanisms operate across different CRC subtypes and patient backgrounds.
• Model systems: While both in vitro and xenograft models provide strong preclinical evidence, clinical translation will require validation in larger patient cohorts and in the context of combination therapies.
• Broader applicability: The precise role of ANTXR1 lactylation and CAF-derived lactate in other cancer types remains unexplored, limiting immediate cross-domain generalizability.

Nonetheless, the study's integration of metabolic, epigenetic, and signaling analyses strengthens its conclusions and provides a solid framework for further inquiry.

Protocol Parameters

• CAF-conditioned medium preparation: Culture CAFs under glycolytic-promoting conditions; collect medium after 48-72 hours for co-culture experiments.
• Lactate quantification: Use enzymatic assays to determine extracellular lactate concentrations in both CAF and CRC cell cultures.
• Chromatin immunoprecipitation (ChIP): Perform ChIP for lactylated histone marks (e.g., H3K18la) followed by qPCR for target gene promoters such as ANTXR1.
• Protein lactylation detection: Employ immunoprecipitation and mass spectrometry to identify lactylated lysine residues, particularly K453 on ANTXR1.
• RNA extraction for gene expression studies: Utilize DNase I (RNase-free) during RNA isolation to prevent DNA contamination in downstream RT-PCR or transcriptomic analyses.

Research Support Resources

For researchers aiming to replicate or extend these findings, robust nucleic acid preparation is critical. DNase I (RNase-free) (SKU K1088) from APExBIO is suitable for the efficient removal of DNA during RNA extraction, in vitro transcription, and chromatin studies. Its efficacy in preventing DNA contamination supports sensitive detection of gene expression and epigenetic modifications, as outlined in both the reference study and internal literature. For detailed workflow guidance, see DNase I (RNase-free): Precision DNA Removal in RNA Extraction.