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

Implications of Toll-like receptors (TLRs) and their signaling mechanisms in human cancers

Most essential pattern-recognition receptors regulating innate immune functions are toll-like receptors (TLRs). TLRs are characterized by lack of concurrent epithelial markers and are typically identified by their gene expressions. One major mechanism by which TLRs generate their effector functions is by triggering inflammatory responses. Activation of TLRs can impact initiation, advancement, and control of cancers by regulating the inflammatory microenvironment. Several TLRs have been implicated in human cancers and some of them are identified as cancer biomarkers as well; for example, TLRs 2, 3, 5 are expressed more frequently in most cancers. Knowing the upregulation and downregulation of the TLR genes in human cancers will be useful for the development of newer therapeutic targets which can disrupt the pathways associated with such deregulation. We present here the various TLRs and their functions in human lung, gastric, breast, prostate, oral, ovarian, colorectal, cervical, esophageal, bladder and hepatic cancers.

TLRs expression in canine mammary gland neoplasms: a pathological and molecular study

TLRs are a class of PRRs that play a vital role in innate immunity. TLRs are expressed on immune cells and mammary epithelial cells. They can promote tumor growth, angiogenesis, invasion, and viability signaling. The current study aimed to test the correlation between histologic types and grades of neoplasms and TLRs gene expression levels. Twenty-one tissue samples of canine mammary neoplasms were stained with H&E. Then, it evaluated histologic type and grade according to the methods of Goldschmidt et al. and Peña, respectively. We established real-time PCR quantification assays to measure the mRNA abundances of TLRs in normal and neoplastic mammary glands. Profile pattern of TLR 1, 2, 3, 4, 5, 6, and 9 genes expression in canine mammary glands performed in 21 samples of mammary gland neoplasms and three non-neoplastic mammary gland samples from normal dogs. TLR 3, 4, and 9 mRNA overexpression were detected. In addition, tubulopapillary carcinoma grade II, SCC grade III, and carcinoma mixed type grade II demonstrated the highest relative TLR-3, and 9 mRNA expression levels. Complex carcinoma grade I, ductal carcinoma grade II, and anaplastic carcinoma grade II showed the highest relative TLR4 mRNA expression level. Although histopathological characteristics of tumors, including histologic type, grade, and inflammation, influenced TLRs mRNA expression level, such correlation was insignificant (P > 0.05).

Long Non-Coding RNA CASC7 Promotes Proliferation and Inhibits Apoptosis of Hepatocellular Carcinoma Cells via Downregulating miR-340-5p CASC7/miR-340-5p Axis in Hepatocellular Carcinoma

Background: Hepatocellular carcinoma (HCC) is a common malignant tumor worldwide with a poor prognosis. Amounting studies revealed that long non-coding RNAs (lncRNAs) show important roles in various biological processes. The purpose of this study was to explore the biological function and potential molecular mechanism of CASC7 in HCC. Methods: CASC7 expression in HCC cell lines was detected by qRT-PCR. The expressions of CASC7 and miR-340-5p were changed by transfection of miR-340-5p mimic, the CASC7 overexpression and knockdown plasmids. The interaction between CASC7 and miR-340-5p was assessed by a Dual-Luciferase reporter assay. The biological functions of CASC7 were evaluated by CCK-8, colony formation assay, ROS assay kit, immunofluorescence and flow cytometry (FCM). Results: CASC7 was upregulated in HCC cell lines. CASC7 overexpression significantly promoted cell proliferation, as well as inhibited apoptosis and oxidative stress. In contrast, CASC7 knockdown could reverse these above changes. The result of the Dual-luciferase reporter assay revealed that CASC7 directly targeted miR-340-5p and negatively regulated its expression. In addition, CASC7 promoted proliferation and inhibited apoptosis of HCC cells through activating Nrf2 pathway by downregulating miR-340-5p. Conclusions: In summary, CASC7 promotes HCC tumorigenesis and progression through the Nrf2 pathway by targeting miR-340-5p, which may provide a new target for therapy of HCC.

Tilsotolimod: an investigational synthetic toll-like receptor 9 (TLR9) agonist for the treatment of refractory solid tumors and melanoma

INTRODUCTION

Cancer immunotherapy has seen tremendous strides in the past 15 years, with the introduction of several novel immunotherapeutic agents. Nevertheless, as clinical practice has shown, significant challenges remain with a considerable number of patients responding sub-optimally to available therapeutic options. Research has demonstrated the important immunoregulatory role of the tumor microenvironment (TME), with the potential to either hinder or promote an effective anti-tumor immune response. As such, scientific efforts have focused on investigating novel candidate immunomodulatory agents with the potential to alter the TME toward a more immunopotentiating composition.

AREAS COVERED

Herein, we discuss the novel investigational toll-like receptor 9 agonist tilsotolimod currently undergoing phase II and III clinical trials for advanced refractory cancer, highlighting its mode of action, efficacy, tolerability, and potential future applications in the treatment of cancer. To this effect, we conducted an exhaustive Web of Science and PubMed search to evaluate available research on tilsotolimod as of August 2021.

EXPERT OPINION

With encouraging early clinical results demonstrating extensive TME immunomodulation and abscopal effects on distant tumor lesions, tilsotolimod has emerged as a potential candidate immunomodulatory agent with the possibility to augment currently available immunotherapy and provide novel avenues of treatment for patients with advanced refectory cancer.

A Combined TLR7/TLR9/GATA3 Score Can Predict Prognosis in Biliary Tract Cancer

Biliary tract cancer (BTC) refers to a heterogenous group of epithelial malignancies arising along the biliary tree. The highly aggressive nature combined with its silent presentation contribute to the dismal prognosis of this tumor. Tumor-infiltrating immune cells (TIICs) are frequently present in BTC and there is growing evidence regarding their role as therapeutic targets. In this study, we analyzed the immune cell infiltration in BTC and developed a promising immune signature score to predict prognosis in BTC. Immunohistochemistry (IHC) was carried out on tissue microarray sections from 45 patients with resectable cholangiocarcinoma for the detection of 6-sulfoLacNAc+ monocytes (slanMo), BDCA-2+ plasmacytoid dendritic cells (pDC), CD8+ or CD4+T-lymphocytes, CD103+ cells, GATA3+ cells, Toll-like receptor (TLR) 3, 7 and 9-expressing cells as well as programmed cell death protein 1 and programmed cell death ligand 1 positive cells. Data from the IHC staining were analyzed and correlated with clinicopathological and survival data. High expression of TLR7, TLR9, and GATA3 was associated with improved overall survival (OS, Log-rank p < 0.05). In addition, TLR9 was associated with better disease-free survival (Log-rank p < 0.05). In the multivariate Cox proportional-hazards model for OS, the TLR/TLR9/GATA3 score was found to be an independent prognostic factor for OS (“Score 2” vs. “Score 0”: HR 11.17 95% CI 2.27–54.95, p < 0.01).

Toll-Like Receptor 9 Expression Levels in Breast Carcinoma Correlate with Improved Overall Survival in Patients Treated with Neoadjuvant Chemotherapy and Could Serve as a Prognostic Marker

Aim: Toll-like receptor 9 (TLR9) can recognize the DNA fragments released from chemotherapy-treated cancer cells in tumor tissues and induce an inflammatory response. The aim of the present study was to evaluate the survivability benefit of TLR9 expression levels as a potential prognostic marker in breast cancer patients treated with neoadjuvant chemotherapy (NACT). Methods: To study the expression of TLR9 in breast tumor, immunohistochemical (IHC) analyses were performed on two patient cohorts, with NACT (n = 19) and without NACT (n = 23). To corroborate the findings from the in-house cohort, we also used publicly available datasets including SurvExpress (GSE 20685) and the Kaplan-Meier plotter tool (GSE 16446) to analyze the relationship between the expression of TLR9 and overall survivability for NACT. Results: The IHC analyses of our inhouse cohort demonstrated that TLR9 was expressed in both malignant breast epithelial cancer cells as well as in the adjacent stromal cells. The IHC results also indicated that, the percentage of malignant epithelial cells (54.76%) expressing TLR9 was higher than in the adjacent stromal compartment (11.9%). We also observed an increase in the expression levels of TLR9 in the patients who were given NACT (p = 0.0379). Further, the analysis of publicly available datasets demonstrated that elevated TLR9 expression was related to increased overall survival in patients treated with NACT. Conclusions: In this study, we show for the first time that elevated TLR9 tissue expression levels in breast cancer may serve as a prognostic marker for patients treated with NACT and could potentially be used to select the neoadjuvant regime.

Toll-like receptor (TLR) gene expression and immunostimulatory effect of CpG oligonucleotides in hormone receptor positive cell line T47D and triple negative breast cancer cell line MDA-MB-468

BACKGROUND

We investigated the expression of TLR genes and the effects of CpG ODN in Estrogen Receptor positive, Progesterone Receptor positive breast cancer cell line (T47D) and a triple-negative breast cancer cell line (MDA-MB-468) followed by studying the immunostimulatory activity of CpG oligonucleotides in breast cancer cell lines T47D and MDA-MB-468.

MATERIALS AND METHODS

We evaluated the expression pattern of TLR genes (TLR1 to TLR9) in T47D and MDA-MB-468 cells using Real-time qPCR analysis. The intracellular TLR9 protein expression was studied by flow cytometry. The effect of CpG ODN on cell viability was tested using MTT assay. The relative expression of pro-inflammatory (IL6 and TNFα) and anti- inflammatory/immunosuppressive cytokines genes (IL10 and TGF beta1) were examined by Real-time qPCR.

RESULTS

We found that MDA-MB-468 cells expressed TLR2, TLR3, TLR6, TLR8, and TLR9 genes and T47D cells expressed TLR3, TRL5, TLR8, and TLR9 genes. Stimulation of TLR9 in vitro with CpG significantly reduced the cell viability of T47D and MDA-MB-468 cells. IL6 cytokine gene expression was significantly reduced in both CpG treated T47D cells and MDA-MB-468 cells. TNFα gene expression was significantly reduced after treatment with CpG in MDA-MB-468 cells but not in T47D cells. IL10 and TGFβ1 expression were downregulated in CpG treated T47D cells. Whereas, IL10 and TGFβ1 were elevated in CpG treated MDA-MB-468 cells.

CONCLUSION

Our in vitro finding gives preliminary evidence that triggering TLR9 using CpG ODN decreases the cell proliferation and alters the pro-inflammatory cytokines in favor of inhibition of hormone receptor positive breast cancer cells T47D and triple negative breast cancer cells MDA-MB-468.

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

The recent emergence of lyn kinase as a driver of aggressive behaviour in triple-negative breast cancer (TNBC) remains a major concern posing a burden for people living with breast cancer and drug development. The binding of UM-164 to lyn protein has been noted to impact the conformational dynamics required for drug fitness. Herein, we provide the first account of the molecular impact of an experimental drug, UM-164 binding on lyn protein using various computational approaches including molecular docking and molecular dynamics simulation. These computational modelling methods enabled us to analyse parameters, for example principal component analysis (PCA), dynamics cross-correlation matrices (DCCM) analysis, hydrogen bond occupancy, thermodynamics calculation and ligand–residue interaction. Findings from these analyses revealed that UM-164 exhibited a higher binding affinity of −9.9 kcal mol⁻¹ with lyn protein than Dasatinib, with a binding affinity of −8.3 kcal mol⁻¹ on docking. It was observed that the binding of UM-164 to lyn protein decreases the capacity of its loop to fluctuate, influences the ligand optimum orientation on the conformational space of lyn protein, and increases the hydrogen bond formation in the lyn-UM-164 system. Also, an increase in drug binding energy of UM-164 was recorded with increasing residue correlation in the lyn-UM-164 system. It is quite informative to note that Met85 was a key stabilising factor in the binding of UM-164 to lyn protein. These findings can provide important insights that will potentially serve as a baseline in the design of novel lyn inhibitors. It could also stimulate further research into multidimensional approaches required to curb the influence of lyn protein in TNBC.

This study provides the first account of the molecular impact of UM-164 binding on lyn protein using various computational approaches.

Beyond PD-1/PD-L1 Inhibition: What the Future Holds for Breast Cancer Immunotherapy

Cancer immunotherapy has altered the management of human malignancies, improving outcomes in an expanding list of diseases. Breast cancer - presumably due to its perceived low immunogenicity - is a late addition to this list. Furthermore, most of the focus has been on the triple negative subtype because of its higher tumor mutational load and lymphocyte-enriched stroma, although emerging data show promise on the other breast cancer subtypes as well. To this point the clinical use of immunotherapy is limited to the inhibition of two immune checkpoints, Programmed Cell Death Protein 1 (PD-1) and Cytotoxic T-lymphocyte-associated Protein 4 (CTLA-4). Consistent with the complexity of the regulation of the tumor - host interactions and their lack of reliance on a single regulatory pathway, combinatory approaches have shown improved efficacy albeit at the cost of increased toxicity. Beyond those two checkpoints though, a large number of co-stimulatory or co-inhibitory molecules play major roles on tumor evasion from immunosurveillance. These molecules likely represent future targets of immunotherapy provided that the promise shown in early data is translated into improved patient survival in randomized trials. The biological role, prognostic and predictive implications regarding breast cancer and early clinical efforts on exploiting these immune-related therapeutic targets are herein reviewed.

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

Introduction

Toll-like receptor 9 (TLR9) is an innate immune system DNA-receptor that regulates tumor invasion and immunity in vitro. Low tumor TLR9 expression has been associated with poor survival in Caucasian patients with triple negative breast cancer (TNBC). African American (AA) patients with TNBC have worse prognosis than Caucasians but whether this is due to differences in tumor biology remains controversial. We studied the prognostic significance of tumor Toll like receptor-9 (TLR9) protein expression among African American (AA) triple negative breast cancer (TNBC) patients. Germline TLR9 variants in European Americans (EAs) and AAs were investigated, to determine their contribution to AA breast cancer risk.

Methods

TLR9 expression was studied with immunohistochemistry in archival tumors. Exome Variant Server and The Cancer Genome Atlas were used to determine the genetic variation in the general EA and AA populations, and AA breast cancer cases. Minor allele frequencies (MAFs) were compared between EAs (n = 4300), AAs (n = 2203), and/or AA breast cancer cases (n = 131).

Results

Thirty-two TLR9 variants had a statistically significant MAF difference between general EAs and AAs. Twenty-one of them affect a CpG site. Rs352140, a variant previously associated with protection from breast cancer, is more common in EAs than AAs (p = 2.20E-16). EAs had more synonymous alleles, while AAs had more rare coding alleles. Similar analyses comparing AA breast cancer cases with AA controls did not reveal any variant class differences; however, three previously unreported TLR9 variants were associated with late onset breast cancer. Although not statistically significant, rs352140 was observed less frequently in AA cases compared to controls. Tumor TLR9 protein expression was not associated with prognosis.

Conclusions

Tumor TLR9 expression is not associated with prognosis in AA TNBC. Significant differences were detected in TLR9 variant MAFs between EAs and AAs. They may affect TLR9 expression and function. Rs352140, which may protect from breast cancer, is 1.6 X more common among EAs. These findings call for a detailed analysis of the contribution of TLR9 to breast cancer pathophysiology and health disparities.

Human TLR gene family members are differentially expressed in patients with urothelial carcinoma of the bladder

PURPOSE

Toll-like receptors (TLRs) have an important role in the activation of both innate and adaptive immunity in response to pathogens and endogenous danger signals from damaged or dying cells. The aim of this study was to determine the relationship between urothelial carcinoma (UC) and TLR expression.

BASIC PROCEDURES

Real-time polymerase chain reaction evaluation was made of the messenger RNA expression of TLRs 1-10 in 24 UC samples and 46 nontumoral bladder tissue samples. The levels of proinflammatory cytokines (IL-1β, IL-6, and IL-8) in the urine samples were also determined with enzyme-linked immunosorbent assay.

MAIN FINDINGS

TLR2-7 and TLR10 expressions were significantly higher in UC than in the control group (P<0.05 for all comparisons). No concordance was found between matched tumor tissue and urine samples in terms of TLR expression. IL-1β, IL-6, and IL-8 levels were significantly higher in urine specimens of patients with UC (P = 0.033, P = 0.001, and P = 0.008, respectively).

PRINCIPAL CONCLUSIONS

The results of this study demonstrated that the TLR gene expression profiles reflect the heterogeneity within UC. These results might also prompt further investigation to better understand the role of the TLR gene family expression in the tumor progression of UC.

Triple negative breast cancer: the kiss of death

One of the most controversial women malignancies, triple negative breast cancers (TNBCs) are critically overviewed here, being focused on data useful in clinical practice or to improve the therapy and patients survival. TNBCs "choose" young women and its "kiss" is, unfortunately deadly in most cases. Currently, few sparse data are available in literature concerning the origins of TNBC. Vasculogenic mimicry detected in TNBCs, seems to be determined by a population of CD133+ cells and may be stimulated by different pharmacological agents such sunitinib. Despite the fact that TNBCs do not usually metastasize through the lymphatic pathways, TNBCs may be characterized by lymphatic invasion and by an increased lymphatic microvascular density. If TNBCs treatment depends on the molecular profile of the tumor, the same statement may be postulated for TNBCs metastasis. Whether metastases have a similar phenotype as the primary tumor remains an enigma. Therefore, the question: 'Could TNBC be subject to a standardized, unanimously accepted therapeutic strategy or is it strictly subclass-dependent?' remains to be further investigated.

Toll-like receptor 9 expression is associated with breast cancer sensitivity to the growth inhibitory effects of bisphosphonates in vitro and in vivo

Bisphosphonates are standard treatments for bone metastases. When given in the adjuvant setting, they reduce breast cancer mortality and recurrence in bone but only among post-menopausal patients. Optimal drug use would require biomarker-based patient selection. Such biomarkers are not yet in clinical use. Based on the similarities in inflammatory responses to bisphosphonates and Toll-like receptor (TLR) agonists, we hypothesized that TLR9 expression may affect bisphosphonate responses in cells. We compared bisphosphonate effects in breast cancer cell lines with low or high TLR9 expression. We discovered that cells with decreased TLR9 expression are significantly more sensitive to the growth-inhibitory effects of bisphosphonates in vitro and in vivo. Furthermore, cancer growth-promoting effects seen with some bisphosphonates in some control shRNA cells were not detected in TLR9 shRNA cells. These differences were not associated with inhibition of Rap1A prenylation or p38 phosphorylation, which are known markers for bisphosphonate activity. However, TLR9 shRNA cells exhibited increased sensitivity to ApppI, a metabolite that accumulates in cells after bisphosphonate treatment. We conclude that decreased TLR9-expression sensitizes breast cancer cells to the growth inhibitory effects of bisphosphonates. Our results suggest that TLR9 should be studied as a potential biomarker for adjuvant bisphosphonate sensitivity among breast cancer patients.