Colonic epithelial cathelicidin (LL‐37) expression intensity is associated with progression of colorectal cancer and presence of CD8⁺ T cell infiltrate

Abstract

Colorectal cancer (CRC) remains a leading cause of cancer mortality. Here, we define the colonic epithelial expression of cathelicidin (LL‐37) in CRC. Cathelicidin exerts pleotropic effects including anti‐microbial and immunoregulatory functions. Genetic knockout of cathelicidin led to increased size and number of colorectal tumours in the azoxymethane‐induced murine model of CRC. We aimed to translate this to human disease. The expression of LL‐37 in a large (n = 650) fully characterised cohort of treatment‐naïve primary human colorectal tumours and 50 matched normal mucosa samples with associated clinical and pathological data (patient age, gender, tumour site, tumour stage [UICC], presence or absence of extra‐mural vascular invasion, tumour differentiation, mismatch repair protein status, and survival to 18 years) was assessed by immunohistochemistry. The biological consequences of LL‐37 expression on the epithelial barrier and immune cell phenotype were assessed using targeted quantitative PCR gene expression of epithelial permeability (CLDN2, CLDN4, OCLN, CDH1, and TJP1) and cytokine (IL‐1β, IL‐18, IL‐33, IL‐10, IL‐22, and IL‐27) genes in a human colon organoid model, and CD3+, CD4+, and CD8+ lymphocyte phenotyping by immunohistochemistry, respectively. Our data reveal that loss of cathelicidin is associated with human CRC progression, with a switch in expression intensity an early feature of CRC. LL‐37 expression intensity is associated with CD8+ T cell infiltrate, influenced by tumour characteristics including mismatch repair protein status. There was no effect on epithelial barrier gene expression. These data offer novel insights into the contribution of LL‐37 to the pathogenesis of CRC and as a therapeutic molecule.

Subcellular Epithelial HMGB1 Expression Is Associated with Colorectal Neoplastic Progression, Male Sex, Mismatch Repair Protein Expression, Lymph Node Positivity, and an ‘Immune Cold’ Phenotype Associated with Poor Survival

“…FFPE tissue cores from 650 CRCs and 50 matched normal pairs were presented within a previously validated TMA [ 13 , 14 , 15 ]. Tissue cores were obtained from chemotherapy and radiotherapy-naïve patients undergoing elective surgery for primary CRC between 1994 and 2009 at Aberdeen Royal Infirmary, Scotland UK.…”

“…These epithelial and immune cell markers were chosen because of previously established biology between them and HMGB1 or cancer [ 13 , 16 ]. Immunohistochemistry was performed using a Dako Autostainer (Dako, Ely, UK), as previously described [ 14 , 15 , 16 ]. Antigen retrieval was performed in 10 mM citrate (pH6) or EDTA (pH 7.8) buffer for 20 min, primary antibody was applied for 60 min, and EnVision+ ™ peroxidase-linked biotin-free synthesis (Dako, Ely, UK) with 3′-3′-diaminobenzidine as chromogen was used for detection.…”

Interleukin-27 Regulates the Function of the Gastrointestinal Epithelial Barrier in a Human Tissue-Derived Organoid Model

“…A human colon-derived epithelial organoid model was established as we previously described [10] from a published protocol [11]. Human colonic mucosa was chelated in 2.5 mM EDTA buffer on ice for 40 min with gentle agitation, then passed through a 100 µM cell strainer.…”

Renovation as innovation: Repurposing human antibacterial peptide LL-37 for cancer therapy

“…In addition, via activating TRPV2 and PI3/Akt signaling, and then inducing recruitment of TRPV2 from intracellular vesicles to the plasma membrane of pseudopodia, LL-37 promotes proliferation and growth of breast cancer cells ( Farabaugh et al, 2016 ). On the contrary, it has also been shown that LL-37 can exert anticancer effects on other cancers, including colon cancer, glioblastoma, hematologic malignancy, gastric cancer, and oral squamous cell carcinoma ( Aarbiou et al, 2006 ; Wu et al, 2010b ; Bruns et al, 2015 ; Prevete et al, 2015 ; Chen et al, 2020 ; Porter et al, 2021 ; Chernov et al, 2022 ). There is no smoking gun to explain the reported opposite effects on different cancer types.…”