The Impact of Focused Ultrasound in Two Tumor Models: Temporal Alterations in the Natural History on Tumor Microenvironment and Immune Cell Response

Gadi Cohen,Parwathy Chandran,Lauren E Tomlinson,Rebecca M Lorsung,Joseph A Frank,Scott R Burks,Maggie Sundby

doi:10.3390/cancers12020350

Abstract

Image-guided focused ultrasound (FUS) has been successfully employed as an ablative treatment for solid malignancies by exposing immune cells to tumor debris/antigens, consequently inducing an immune response within the tumor microenvironment (TME). To date, immunomodulation effects of non-ablative pulsed-FUS (pFUS) on the TME are poorly understood. In this study, the temporal differences of cytokines, chemokines, and trophic factors (CCTFs) and immune cell populations induced by pFUS were interrogated in murine B16 melanoma or 4T1 breast cancer cells subcutaneously inoculated into C57BL/6 or BALB/c mice. Natural history growth characteristics during the course of 11 days showed a progressive increase in size for both tumors, and proteomic analysis revealed a shift toward an immunosuppressive TME. With respect to tumor natural growth, pFUS applied to tumors on days 1, 5, or 9 demonstrated a decrease in the growth rate 24 h post-sonication. Flow cytometry analysis of tumors, LNs, and Sp, as well as CCTF profiles, relative DNA damage, and adaptive T-cell localization within tumors, demonstrated dynamic innate and adaptive immune-modulation following pFUS in early time points of B16 tumors and in advanced 4T1 tumors. These results provide insight into the temporal dynamics in the treatment-associated TME, which could be used to evaluate an immunomodulatory approach in different tumor types.

Highlights

Tumors exist as a complex heterogenous milieu comprising populations of neoplastic cells, stromal cells, immune cells, secreted factors, vasculature, and extracellular matrices (ECMs), collectively acknowledged as the tumor microenvironment (TME) [1,2,3,4]
We evaluated the natural history of the CCTF and cell adhesion molecules (CAMs) changes in 4T1 and B16 flank tumors over a period of 11 days to determine how the TME was altered with tumor growth
This study examined the proteomic changes in B16 and 4T1 flank tumors with respect to their growth in size over time, demonstrating temporal shifts that could favor either an anti-tumor or an immunosuppressive TME

Summary

Introduction

Tumors exist as a complex heterogenous milieu comprising populations of neoplastic cells, stromal cells, immune cells, secreted factors, vasculature, and extracellular matrices (ECMs), collectively acknowledged as the tumor microenvironment (TME) [1,2,3,4]. Various cellular and biological immunotherapies have revolutionized the treatment of human malignancies by shifting the balance from an immunosuppressive to an anti-tumor TME by modulating immune cell populations within solid tumors. These approaches are associated with limited therapeutic efficacy [17,18,19], and interventional approaches are still considered as a stand-alone treatment or in combination with chemotherapy and/or radiation therapy for many patients with solid tumors [20]. We recently characterized changes in CCTFs, CAMs, and immune cell infiltration

Methods

Results

Discussion

Conclusion