Association of Toll like receptor 9 expression with lymph node metastasis in human breast cancer

Toll-like receptors in breast cancer immunity and immunotherapy

Toll-like receptors (TLRs) are a key family of pattern recognition receptors (PRRs) in the innate immune system. The activation of TLRs will not only prevent pathogen infection but also respond to damage-induced danger signaling. Increasing evidence suggests that TLRs play a critical role in breast cancer development and treatment. However, the activation of TLRs is a double-edged sword that can induce either pro-tumor activity or anti-tumor effect. The underlying mechanisms of these opposite effects of TLR signaling in cancer are not fully understood. Targeting TLRs is a promising strategy for improving breast cancer treatment, either as monotherapies or by improving other current therapies. Here we provide an update on the role of TLRs in breast cancer immunity and immunotherapy.

Associations Between Serum Soluble Toll-like Receptors 4 and 9 and Breast Cancer in Egyptian Patients

BACKGROUND

Toll-like receptors (TLRs) play an important role in regulation of immune cells and are vital in tumorigenesis due to its crucial role in inflammatory microenvironment regulation, as they promote the synthesis and release of inflammatory cytokines and chemokines. Toll-like receptors 4 and TLRs 9 were found to be highly expressed in breast cancer. The aim of this study is to investigate the soluble toll-like receptors 4 and 9 (sTLR4 and sTLR9) as potential biomarkers for diagnosis and prognosis of breast cancer and their association with the clinicopathological parameters of breast cancer.

PATIENTS AND METHOD

In this retrospective case-control study, 186 female subjects were recruited and divided into three groups, Group I: 62 healthy control, Group II: 62 subjects diagnosed with non-metastatic breast cancer, and Group III: 62 subjects diagnosed with metastatic breast cancer. Enzyme-linked immunosorbent assay (ELISA) technique was used to quantify the levels of sTLR4 and sTLR9 in serum.

RESULTS

Both non-metastatic and metastatic groups showed significant higher levels of both serum sTLR4 and sTLR9 expression compared to healthy controls. Only sTLR9 was significantly increased among metastatic patients compared to non-metastatic group. Serum levels of sTLR9 and sTLR4 were still significantly associated with breast cancer in a multiple logistic regression model (P = <.001). ROC curves showed that both sTLR4 and sTLR9 can be a significant parameter to discriminate between normal females and breast cancer patients.

CONCLUSION

Soluble toll-like receptors 4 and sTLR9 are over-expressed in patients with metastatic and non-metastatic BC than in benign cases. The expression levels of sTLR4 and TLR9 have clinical interest as indicators of tumor aggressiveness suggested to be prognostic biomarkers. Toll-like receptors may represent therapeutic targets in breast cancer.

The therapeutic potential of targeting Toll like receptor pathway in breast cancer

The toll-like receptor (TLR) signaling pathway plays a key role in inducing immune responses and were shown to be expressed in immune cells and tumor cells, and is involved in the progression of several malignancies including breast cancer. These findings provide a proof of the concept of targeting this pathway as a potential therapeutic option in the treatment of breast cancer. Moreover, there is a growing body of data showing the activation of TLRs in the tumor microenvironment and its dual function as anti-tumoral (dendritic T and natural killer cells activation) or pro-tumoral activity (cell proliferation, and drug resistance). Several agents have been developed for targeting of this pathway and one of these inhibitors, called Bacillus Calmette-Guerin (an agonist of TLR2 and TLR4), is recently being approved by FDA for immunotherapy of bladder cancer. This review summarizes the current knowledge of the mechanisms of action of TLR pathways in the development/progression of cancer for a better management of this disease.

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.

Association of toll-like receptor 9 expression with prognosis of systemic lupus erythematosus

The current study assessed the association between toll-like receptor 9 (TLR9) and systemic lupus erythematosus (SLE) and subsequently determined the predictive value of TLR9 in assessing the prognosis of SLE. A total of 90 newly diagnosed patients with SLE and 49 healthy control subjects were enrolled in the current study. The expression of TLR9 mRNA was measured in whole blood samples from patients and controls. All patients were followed up for ≥2 years and their clinical parameters were recorded. After 2 years, 30 patients were randomly chosen from patient subgroups with high (n=20) or low (n=10) TLR9 levels and the expression of TLR9 mRNA were measured again. Cox proportional hazards regression was used to identify the risk factors of SLE prognosis. Patients with SLE and high SLE disease activity exhibited significantly increased TLR9 expression (P<0.05). Persistent proteinuria of >0.5 g/day [hazard ratio (HR), 6.314; 95% confidence interval (CI), 2.858-13.947], C-reactive protein levels (HR, 1.013; 95% CI, 1.007-1.019) and high-TLR9 mRNA expression (HR, 3.852; 95% CI, 1.931-7.684) were independent risk factors of poor prognosis during a 2-year follow-up period, whereas patient treatment with >1 immunosuppressant (HR, 0.374; 95% CI, 0.173-0.808) was a factor indicating favorable prognosis. Furthermore, the expression of TLR9 mRNA remained high in patients with poor prognosis at the end of a 2-year follow-up period but in patients with a favorable prognosis, TLR9 mRNA expression was significantly reduced compared with the levels measured at SLE onset (P<0.0001). Therefore, the expression of TLR9 mRNA in whole blood samples at SLE onset is associated with SLE disease activity and its expression may be used as an indicator of poor prognosis in patients with SLE.

Cell-free DNA derived from cancer cells facilitates tumor malignancy through Toll-like receptor 9 signaling-triggered interleukin-8 secretion in colorectal cancer

Circulating cell-free DNA (cfDNA) has become a potential diagnostic and prognostic biomarker for colorectal cancer (CRC). In non-cancerous diseases, it has been confirmed that cfDNA can be recognized by Toll-like receptor 9 (TLR9), leading to a significant biological change. Nevertheless, the biological significance of cfDNA and its relationship with TLR9 in tumor malignancy is still unclear. Therefore, the purpose of this study is to explore the biological role of cfDNA in colorectal cancer (CRC). The expression of TLR9 was measured in different CRC cell lines and cancerous samples by RT-PCR or immunohistochemistry, which showed that high expression of TLR9 was significantly correlated with the tumor metastasis, advanced TNM stage and poor prognosis of patients. Then, cfDNA was obtained from fluorouracil (5FU)-induced apoptotic cancer cells in vitro and transfection techniques were used to transfect siRNA and cDNA plasmid for TLR9. Cancer cells were stimulated using isolated cfDNA fragments, and results showed that cfDNA could promote colorectal cancer cell proliferation via TLR9. Meanwhile, we demonstrated that the cfDNA binding to TLR9 could facilitate cell migration and invasion. Finally, we demonstrated that cfDNA initiated downstream TLR9-MyD88 signaling and induced robust release of chemokine interleukin 8 (IL-8), which helped to elucidate the mechanisms underlying these phenomena. Our data suggest that cancer cell-derived cfDNA contributes to cancer progression through activation of TLR9-MyD88 signaling and IL-8 secretion in CRC. These findings provide a novel perspective for understanding of tumor progression and provoke a potential therapeutic target for CRC treatment.

Naltrexone Inhibits IL-6 and TNFα Production in Human Immune Cell Subsets following Stimulation with Ligands for Intracellular Toll-Like Receptors

The opioid antagonist naltrexone hydrochloride has been suggested to be a potential therapy at low dosage for multiple inflammatory conditions and cancers. Little is known about the immune-modulating effects of naltrexone, but an effect on the activity of toll-like receptor 4 (TLR4) has been reported. We analyzed the effects of naltrexone hydrochloride on IL-6 secretion by peripheral blood mononuclear cells (PBMC) in vitro following stimulation with ligands for TLR4 and for the intracellular receptors TLR7, TLR8, and TLR9. Naltrexone did not affect cell viability or induce apoptosis of PBMC. Intracellular staining demonstrated that naltrexone inhibited production of IL-6 and TNFα by monocyte and plasmacytoid dendritic cell subsets within the PBMC population following treatment with ligands for TLR7/8 and TLR9, respectively. No effect of cytokine production by PBMC following stimulation of TLR4 was observed. Additionally, naltrexone inhibited IL-6 production in isolated monocytes and B cells after TLR7/8 and TLR9 stimulation, respectively, but no effect on IL-6 production in isolated monocytes after TLR4 stimulation was observed. These findings indicate that naltrexone has the potential to modulate the secretion of inflammatory cytokines in response to intracellular TLR activity, supporting the hypothesis that it may have potential for use as an immunomodulator.

Screening for transcription factors and their regulatory small molecules involved in regulating the functions of CL1-5 cancer cells under the effects of macrophage-conditioned medium

Many reports have inferred that macrophages can interact with tumor cells in the tumor microenvironment (TME) in a vicious cycle of tumor development; however, the changes in gene expression in tumor cells under the effects of macrophages are still largely unknown. The present study was carried out to illustrate the changes in the gene expression profile in lung cancer cells under the effects of macrophage-conditioned medium. Gene expression profile data were derived from the GEO database GSE9315. The GSM234968 sample was derived from a highly invasive human pulmonary adenocarcinoma cell line, CL1-5, and was treated with conditioned medium (supernatant of a culture solution of human monocyte THP-1). The GSM234967 sample that was not treated with the conditioned medium was used as a control. GO and KEGG enrichment analyses were carried out using DAVID software, and visualization networks were constructed using Cytoscape software. The results showed that 40 differentially expressed genes were annotated. Five differentially expressed transcription factors were identified, EIF2B4, EIF2B5, JUNB, GNG11 and HMGB2, which were all related to 'stress' and 'responses'. The gene cluster of JUNB was mainly enriched in cancer-related pathways, 'Wnt signaling pathway' and 'MAPK signaling pathway'. Finally, 10 small molecules, thioridazine, resveratrol, astemizole, ciclopirox, calmidazolium, etoposide, anisomycin, pyrvinium, azacyclonol and terfenadine, which may act on transcription factors, were identified using the CMap database. In conclusion, we identified transcription factors playing key roles in tumor cells under the effects of macrophages in order to provide new clues for blocking this vicious cycle of tumor development.

The roles of beta-adrenergic receptors in tumorigenesis and the possible use of beta-adrenergic blockers for cancer treatment: possible genetic and cell-signaling mechanisms

Cancer is the leading cause of death in the USA, and the incidence of cancer increases dramatically with age. Beta-adrenergic blockers appear to have a beneficial clinical effect in cancer patients. In this paper, we review the evidence of an association between β-adrenergic blockade and cancer. Genetic studies have provided the opportunity to determine which proteins link β-adrenergic blockade to cancer pathology. In particular, this link involves the major histocompatibility complex class II molecules, the renin-angiotensin system, transcription factor nuclear factor-kappa-light-chain-enhancer of activated B cells, poly(ADP-ribose) polymerase-1, vascular endothelial growth factor, and the reduced form of nicotinamide adenine dinucleotide phosphate oxidase. Beta-adrenergic blockers also exert anticancer effects through non-genomic factors, including matrix metalloproteinase, mitogen-activated protein kinase pathways, prostaglandins, cyclooxygenase-2, oxidative stress, and nitric oxide synthase. In conclusion, β-adrenergic blockade may play a beneficial role in cancer treatment. Additional investigations that examine β-adrenergic blockers as cancer therapeutics are required to further elucidate this role.