Downregulation of MUC1 Enhances Antitumor Response in Colon Cancer Model by Decreasing PD-L1 Expression In Vivo and...

Area of Science:

• Oncology
• Immunology
• Molecular Biology

Background:

• Colorectal cancer (CRC) has poor survival rates, necessitating novel diagnostic and therapeutic targets.
• Mucin 1 (MUC1), a transmembrane glycoprotein, influences tumor metabolism and has shown antitumor effects in other cancers, but its role in CRC remains unclear.
• Understanding MUC1's mechanism in CRC is crucial for developing effective treatments.

Purpose of the Study:

• To investigate the molecular mechanism of Mucin 1 (MUC1) in colorectal cancer (CRC).
• To determine the relationship between MUC1 expression and immune responses in CRC.
• To explore MUC1's potential as a therapeutic target for CRC.

Main Methods:

• Immunohistochemistry and Western blot to assess MUC1 expression in tumor and normal tissues.
• MUC1 knockdown/overexpression studies and miR-200c analysis.
• Quantitative real-time PCR (Q-PCR), western blot, immunoprecipitation, and flow cytometry to elucidate molecular pathways involving NF-κB p65 and PD-L1.

Main Results:

• MUC1 expression positively correlates with PD-L1 expression and is upregulated in colon carcinoma tissues.
• MUC1 upregulation promotes CD8+ T cell immune tolerance, immune failure, and infiltration of regulatory T cells (Treg), myeloid-derived suppressor cells (MDSCs), and associated tumor microenvironment cells (ATM).
• MUC1 downregulates PD-L1 via NF-κB p65 and miR-200c; MUC1 downregulation enhances anti-tumor immunity and reduces immune-suppressive cell infiltration.

Conclusions:

• MUC1 plays a significant role in promoting immune evasion in colorectal cancer by modulating PD-L1 expression.
• Downregulating MUC1 enhances the anti-tumor immune response through the NF-κB p65 and miR-200c pathways by reducing PD-L1.
• Targeting MUC1 presents a promising therapeutic strategy to overcome immune resistance in colorectal cancer.