Biopathological Significance of TLR9 Expression in Cancer Cells and Tumor Microenvironment Across Invasive Breast Carcinomas Subtypes

Abstract

Toll-like receptors (TLRs) are pattern recognition receptors mainly expressed by cells of the immune system but also by epithelial tumor cells. Little is known about expression patterns of TLR genes in breast tumors, and their clinical significance is unclear. The aim of our study was to investigate expression of TLRs pathway components in pre-invasive breast lesions and invasive breast carcinomas (IBCs). We used RT-PCR assays to quantify mRNA levels of the 10 TLR genes and genes involved in TLR pathways in 350 breast tumors from patients with known clinical/pathological status and long-term outcome. Sets of 158 breast samples were also analyzed by immunochemistry including; 40 early noninvasive breast lesions, 38 IBCs and 80 triple negative carcinomas subtype (TNCs). We identified TLR9 as the major TLR gene family member upregulated in breast tumors and more particularly in TNCs. Immunohistochemical studies demonstrated that TLR9 protein was expressed in tumor epithelial and stromal cells of the TLR9 mRNA-overexpressing tumors. TLR9 overexpression appears very early during breast carcinogenesis. High TLR9 levels were associated with favorable outcome in the TNC sub-group. TLR9 overexpression was associated with alterations of down-stream components of the TLR9 signaling pathway, epithelio-mesenchymal transition (EMT) induction and EGFR pathway deregulation. TNCs with TLR9 overexpression were significantly correlated with development of a fibrous and inflammatory microenvironment with variable status of nuclear phosphoSTAT3. Our results suggest that TLR9 could play a role in TNC carcinogenesis and could be useful as predictive biomarker and therapeutic target.Keywords Toll-like receptor 9 . Breast cancer subtypes .

Lower frequency of TLR9 variant associated with protection from breast cancer among African Americans

“…[ 15 ] This finding has since been independently verified by a group of French scientists. [ 32 ] Furthermore, these findings are not limited to TNBC as low TLR9 expression predicts poor survival also in renal cell carcinoma, pancreatic cancer and possibly also in mucoepidermoid salivary gland carcinoma. [ 13 , 31 , 33 ] Whether low tumor TLR9 expression is only a biomarker for poor survival, or whether it actually contributes to cancer pathophysiology in these tumors, is not currently known.…”

“…[ 15 , 33 ] Ethnicity of the patients with results similar to ours was not disclosed in the French cohort. [ 32 ] Despite these promising results, tumor TLR9 expression is not currently used as a prognostic clinical tool. To be used as such will require further clinical studies, and preferably a demonstration that use of the TLR9 biomarker improves patient outcomes.…”

Significance of Tumor Microenvironment Scoring and Immune Biomarkers in Patient Stratification and Cancer Outcomes

“…Comparatively, in triple-negative breast cancer, three TME subtypes using IHC analyses have been identified: (1) a first subtype with TLR9 high expression by cancer cells, hypercellular stroma and numerous TILs overexpressing TLR9; (2) a second subtype with TLR9 low expression by cancer cells, a predominantly paucicellular stroma, and rare inflammatory cells expressing TLR9 without TILs; and (3) a third subtype with TLR9 low expression by cancer cells, a predominantly fibrotic and vascular stroma containing some immune and inflammatory cells [55].…”

An analogue of a kinase inhibitor exhibits subjective characteristics that contribute to its inhibitory activities as a potential anti-cancer candidate: insights through computational biomolecular modelling of UM-164 binding with lyn protein

“…6 The aggressive behaviour of TNBCs may be attributed to cellular senescence and cytoprotective autophagy that can enhance the malignant phenotype responsible for this disease. 11,12 The major histopathological changes resulting from a genetic mutation that occurs in TNBC include brosis and inammation, 13 hence the establishment of a panel of markers for the diagnosis of TNBCs metastasis is said to be a welcome idea. However, TNBCs usually exhibit a negative prole for most markers of breast origin 13 consequently, routine diagnosis becomes a difficult tax.…”

“…11,12 The major histopathological changes resulting from a genetic mutation that occurs in TNBC include brosis and inammation, 13 hence the establishment of a panel of markers for the diagnosis of TNBCs metastasis is said to be a welcome idea. However, TNBCs usually exhibit a negative prole for most markers of breast origin 13 consequently, routine diagnosis becomes a difficult tax. 14 Efforts have been made in establishing a panel of makers with clinical usage for proper diagnosis of TNBCs metastases, 14 this was mate with stiff challenges.…”