TLR4 and pSTAT3 Expression on Circulating Tumor Cells (CTCs) and Immune Cells in the Peripheral Blood of Breast Cancer Patients: Prognostic Implications.

Maria A Papadaki,Chara Papadaki,Dimitrios Mavroudis,Katerina Alexakou,Kleita Michaelidou,Christina A Apostolopoulou,Alexia Monastirioti,Sofia Agelaki,Despoina Aggouraki,Maria Vassilakopoulou

doi:10.3390/cancers14041053

Maria A Papadaki, Chara Papadaki + Show 8 more

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https://doi.org/10.3390/cancers14041053

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Journal: Cancers	Publication Date: Feb 18, 2022
Citations: 7	License type: CC BY 4.0

Affiliation: University of Crete, University Hospital of Heraklion

Abstract

Simple SummaryToll-like receptor 4 (TLR4) and phosphorylated signal transducer and activator of transcription protein 3 (pSTAT3) play a prominent role in cancer inflammation and anti-tumor immune response, and their therapeutic targeting is considered a promising strategy for the management of breast cancer (BC). We herein hypothesized that these immunomodulatory molecules may be involved in peripheral tumor-immune crosstalk and could provide valuable prognostic information. Our results provide first evidence that the expression of TLR4 and pSTAT3 on circulating tumor cells (CTCs) and immune cells of BC patients might play a role in peripheral anti-tumor response and metastatic progression, and could be associated with patient outcomes.TLR4 and pSTAT3 are key players in cancer inflammation and immune evasion; however, their role in the peripheral blood (PB) is largely unexplored. Herein we evaluated their expression in the circulating tumor cells (CTCs) and peripheral-blood mononuclear cells (PBMCs) of patients with early (n = 99) and metastatic (n = 100) breast cancer (BC). PB samples obtained prior to adjuvant and first-line therapy, were immunofluorescently stained for Cytokeratins/TLR4/pSTAT3/DAPI and analyzed via Ariol microscopy. TLR4+ CTCs were detected in 50% and 68% of early and metastatic CTC-positive patients, respectively, and pSTAT3+ CTCs in 83% and 68%, respectively. In metastatic patients, CTC detection was associated with a high risk of death (HR: 1.764, p = 0.038), while TLR4+ CTCs correlated with a high risk of disease progression (HR: 1.964, p = 0.030). Regarding PBMCs, TLR4 expression prevailed in metastatic disease (p = 0.029), while pSTAT3 expression was more frequent in early disease (p = 0.014). In early BC, TLR4 expression on PBMCs independently predicted for high risk of relapse (HR: 3.549; p = 0.009), whereas in metastatic BC, TLR4+/pSTAT3− PBMCs independently predicted for high risk of death (HR: 2.925; p = 0.012). These results suggest that TLR4/pSTAT3 signaling on tumor- and immune-cell compartments in the PB could play a role in BC progression, and may hold independent prognostic implications for BC patients.

Highlights

According to the “cancer immunoediting” theory, newly arising tumors are recognized and destroyed by the immune system
We previously demonstrated that CD47 and Progressive disease (PD)-L1, two putative immune checkpoints involved in tumor escape, are more frequently expressed on circulating tumor cells (CTCs) compared to the corresponding primary or metastatic tumor tissues of breast cancer (BC) patients, and that these
Among the 99 metastatic BC patients who were eligible for survival analysis, 84 had progressed and 76 had died at the time of analysis

Summary

Introduction

According to the “cancer immunoediting” theory, newly arising tumors are recognized and destroyed by the immune system. Malignant cells can exploit different mechanisms to escape from immune surveillance, driving the development and growth of a clinically detectable tumor, and subsequently the formation of metastasis [1]. The overcoming of tumor immune evasion formed the basis for the development of different immunotherapy strategies that have already been introduced in clinical practice for the treatment of solid tumors, including triple-negative breast cancer (BC) [2,3]. Cancer-associated inflammation represents another hallmark of cancer, which contributes to genomic instability, epigenetic modification, and the proliferation and dissemination of tumor cells [4]. Studies of the last two decades converge on the existence of a link between chronic inflammation and immune malfunctioning within the tumor microenvironment (TME) [5,6]. Two molecules with a key role in both cancer-associated inflammatory response and immune suppression are toll-like receptor 4 (TLR4) [7] and signal transducer and activator of transcription protein 3 (STAT3) [8]

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