The GRP94 Inhibitor PU-WS13 Decreases M2-like Macrophages in Murine TNBC Tumors: A Pharmaco-Imaging Study with 99mTc-Tilmanocept SPECT

Triple-negative breast cancer (TNBC) is the most aggressive subtype of breast cancers and is not eligible for hormone and anti-HER2 therapies. Identifying therapeutic targets and associated biomarkers in TNBC is a clinical challenge to improve patients’ outcome and management. High infiltration of CD206+ M2-like macrophages in the tumor microenvironment (TME) indicates poor prognosis and survival in TNBC patients. As we previously showed that membrane expression of GRP94, an endoplasmic reticulum chaperone, was associated with the anti-inflammatory profile of human PBMC-derived M2 macrophages, we hypothesized that intra-tumoral CD206+ M2 macrophages expressing GRP94 may represent innovative targets in TNBC for theranostic purposes. We demonstrate in a preclinical model of 4T1 breast tumor-bearing BALB/c mice that (i) CD206-expressing M2-like macrophages in the TME of TNBC can be specifically detected and quantified using in vivo SPECT imaging with 99mTc-Tilmanocept, and (ii) the inhibition of GRP94 with the chemical inhibitor PU-WS13 induces a decrease in CD206-expressing M2-like macrophages in TME. This result correlated with reduced tumor growth and collagen content, as well as an increase in CD8+ cells in the TME. 99mTc-Tilmanocept SPECT imaging might represent an innovative non-invasive strategy to quantify CD206+ tumor-associated macrophages as a biomarker of anti-GRP94 therapy efficacy and TNBC tumor aggressiveness.

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Radioactive Labeling of Milk-Derived Exosomes with 99mTc and In Vivo Tracking by SPECT Imaging

Nanomaterials ◽

10.3390/nano10061062 ◽

2020 ◽

Vol 10 (6) ◽

pp. 1062 ◽

Cited By ~ 4

Author(s):

María Isabel González ◽

Pilar Martín-Duque ◽

Manuel Desco ◽

Beatriz Salinas

Keyword(s):

Single Photon ◽

Photon Emission ◽

Spect Imaging ◽

Emission Computed Tomography ◽

Histological Techniques ◽

Non Invasive ◽

Longitudinal Tracking ◽

Pharmacokinetic Properties ◽

Photon Emission Computed Tomography

Over the last decade, exosomes from diverse biological sources have been proposed as new natural platforms in drug delivery. Translation of these nanometric tools to clinical practice requires deep knowledge of their pharmacokinetic properties and biodistribution. The pharmacokinetic properties of exosomes are sometimes evaluated using biochemical and histological techniques that are considerably invasive. As an alternative, we present radiochemical labeling of milk-derived exosomes based on reduced 99mTc (IV) without modifying biological and physicochemical properties. This approach enables longitudinal tracking of natural exosomes by non-invasive single photon emission computed tomography (SPECT) imaging and the evaluation of their pharmacokinetic properties according to the route of administration.

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Bone marrow CD8 cells down-modulate membrane IL-7Rα expression and exhibit increased STAT-5 and p38 MAPK phosphorylation in the organ environment.

Blood ◽

10.1182/blood-2006-09-045807 ◽

2007 ◽

Vol 110 (6) ◽

pp. 1960-1969 ◽

Cited By ~ 25

Author(s):

Giuliana Cassese ◽

Elisabetta Parretta ◽

Laura Pisapia ◽

Angela Santoni ◽

John Guardiola ◽

...

Keyword(s):

Bone Marrow ◽

Lymph Nodes ◽

Ex Vivo ◽

Mitogen Activated Protein Kinase ◽

Membrane Expression ◽

Cd8 Cells ◽

Interleukin 7 ◽

Polycytidylic Acid

Abstract By comparing mature CD8-cell turnover in different organs, we previously demonstrated that CD8 cells proliferate predominantly in the bone marrow (BM). To investigate the mechanisms underlying such increased turnover, we compared BM, lymph nodes, and spleen CD8 cells from untreated C57BL/6 mice regarding in vivo proliferation within the organ; in vitro response to interleukin-7 (IL-7), IL-15, IL-21; ex vivo expression of membrane CD127 (IL-7Rα), intracellular Bcl-2, phospho–STAT-5 (signal transducer and activator of transcription 5), phospho-p38 mitogen activated protein kinase (MAPK); and in vivo proliferation on adoptive transfer. In the BM, the proliferation rate was increased for either total CD8 cells or individual CD44 and CD122 subsets. In contrast, purified CD8+ cells from the BM did not show an enhanced in vitro proliferative response to IL-7, IL-15, and IL-21 compared with corresponding spleen cells. After transfer and polyinosinic-polycytidylic acid (polyI:C) treatment, both spleen-derived and BM-derived CD8 cells from congenic donors proliferated approximately twice more in the recipient BM than in spleen and lymph nodes. Our results suggest that BM CD8 cells are not committed to self-renewal, but rather are stimulated in the organ. Molecular events constantly induced in the CD8 cells within the BM of untreated mice include increase of both phosphorylated STAT-5 and phosphorylated p38 intracellular levels, and the reduction of CD127 membrane expression.

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