Optical In Vivo Imaging of the Alarmin S100A9 in Tumor Lesions Allows for Estimation of the Individual Malignant Potential by Evaluation of Tumor–Host Cell Interaction

Abstract

Tumors recruit and reprogram immune cells to support tumor development and spread, the most prominent among them being of monocytic origin such as tumor-associated macrophages (TAM) or myeloid-derived suppressor cells (MDSC). The alarmin S100A8/ A9 has been implicated in the induction of TAM and MDSC. We assessed S100A9 as a molecular imaging marker for the activity of tumor-associated immune cells in a syngeneic murine breast cancer model. S100A9 could serve as a surrogate marker for tumor immune crosstalk as a function of malignancy, providing a tool with the potential for both basic research in tumor immunology and clinical stratification of patients. Methods: BALB/c mice were inoculated with murine breast cancer cells of common origin but different metastatic capability. At different times during tumor development, optical imaging was performed using a S100A9-specific probe to visualize activated monocytes. To further explore the impact of tumor-educated monocytes, splenic myeloid cells were isolated from either healthy or tumor-bearing animals and injected into tumor-bearing mice. We analyzed the effect of the cell transfer on immune cell activity and tumor development. Results: We could prove S100A9-driven imaging to sensitively and specifically reflect monocyte activity in primary tumor lesions. The imaging results were corroborated by histology and fluorescence-activated cell sorting analyses. In a prospective experiment, S100A9 imaging proved indicative of the individual tumor growth, with excellent correlation. Moreover, we could show that the monocyte activity as depicted by S100A9 activity in the primary tumor lesion mirrored the tumor's metastatic behavior. Treatment with tumor-primed splenic monocytes induced increased tumor growth, accompanied by an augmented infiltration of activated myeloid cells (MDSC and TAM) into the tumor. The consecutive S100A9 expression as depicted by in vivo imaging was significantly increased. Conclusion: S100A9 proved to be a sensitive and specific marker for the activity of tumor-associated immune cells. To our knowledge, S100A9 imaging represents a first in vivo imaging approach for the estimation of recruitment and activity of tumorassociated myeloid immune cells. We demonstrated the potential value of this imaging approach for prediction of local and systemic tumor development.

Involvement of calprotectin (S100A8/A9) in molecular pathways associated with HNSCC

“…The biological effects of S100A8/A9 depend on the extra- or intracellular localization of the protein complex. Likely released by infiltrating polymorphonuclear leukocytes, macrophages [ 13 , 14 ], and by epithelial cells, extracellular S100A8/A9 in the tumor microenvironment is associated with inflammation-induced tumor progression [ 15 ] and may serve as a prognostic marker in some types of cancer [ 16 , 17 ]. For example, S100A8/A9 is often abnormally elevated in tumors originating in tissues that are negative for the protein complex, whereas intracellular levels decrease in tumors such as HNSCC that originate from tissues with constitutive expression [ 1 ].…”

Visualization of Tumor-Immune Interaction - Target-Specific Imaging of S100A8/A9 Reveals Pre-Metastatic Niche Establishment

“…Several different cells including various tumor cells and immune cells have been reported as potential producers and providers of S100A8/A9 and this can also be found in the tumor microenvironment as well as in premetastatic tissue. For the experimental model we have been using, we could however exclude tumor cells as the source of S100A8/A9, by analysis of cell lysates and tissue culture supernatants, and by FACS of harvested tumor tissue, showing virtually all S100A9 + cells in the 4T1.2 model, to be CD11b + 15. Metastatic breast cancer is known to secrete CCL2 39, which can stimulate MDSC-like and trigger S100A8/A9 release (Fig.…”

“…We recently established target-specific in vivo S100A8/A9 optical imaging for monitoring of monocyte activity in local inflammation 14 and primary cancer lesions 15, using fluorescence-labeled antibodies. The local S100A8/A9-release correlated with the accumulation of tumour-associated CD11b + cells and proved predictive of tumor development.…”

Utility of Different Immunohistochemical Stain for Diagnosis of Invasive Breast Cancer

“…It will promote the circulating breast tumor cells to seed the lung. Becker A also reported that S100A8 has been implicated in the induction of tumor associated macrophaged (TAM) or myeloid-derived suppressor cells (MDSC), which support tumor development and spread [35]. Also there are increasing studies showed the signaling pathways of S100A8 in breast cancer, such as p38-MAPK, IL6 -JAK2-STAT3 [36] and so on.…”