Intracellular Signaling Responses Induced by Radiation within an In Vitro Bone Metastasis Model after Pre-Treatment with an Estrone Analogue.

Jolene Helena,Magdalena Coetzee,Roy Lakier,Anna Joubert,Peace Mabeta,Anne Mercier

doi:10.3390/cells10082105

Jolene Helena, Magdalena Coetzee + Show 4 more

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https://doi.org/10.3390/cells10082105

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Journal: Cells	Publication Date: Aug 17, 2021
Citations: 2	License type: CC BY 4.0

Affiliation: University of Pretoria, Steve Biko Hospital

Abstract

2-Ethyl-3-O-sulfamoyl-estra-1,3,5(10)16-tetraene (ESE-16) is an in silico-designed estradiol analogue which has improved the parent compound’s efficacy in anti-cancer studies. In this proof-of-concept study, the potential radiosensitizing effects of ESE-16 were investigated in an in vitro deconstructed bone metastasis model. Prostate (DU 145) and breast (MDA-MB-231) tumor cells, osteoblastic (MC3T3-E1) and osteoclastic (RAW 264.7) bone cells and human umbilical vein endothelial cells (HUVECs) were representative components of such a lesion. Cells were exposed to a low-dose ESE-16 for 24 hours prior to radiation at non-lethal doses to determine early signaling and molecular responses of this combination treatment. Tartrate-resistant acid phosphatase activity and actin ring formation were investigated in osteoclasts, while cell cycle progression, reactive oxygen species generation and angiogenic protein expression were investigated in HUVECs. Increased cytotoxicity was evident in tumor and endothelial cells while bone cells appeared to be spared. Increased mitotic indices were calculated, and evidence of increased deoxyribonucleic acid damage with retarded repair, together with reduced metastatic signaling was observed in tumor cells. RAW 264.7 macrophages retained their ability to differentiate into osteoclasts. Anti-angiogenic effects were observed in HUVECs, and expression of hypoxia-inducible factor 1-α was decreased. Through preferentially inducing tumor cell death and potentially inhibiting neovascularization whilst preserving bone physiology, this low-dose combination regimen warrants further investigation for its promising therapeutic application in bone metastases management, with the additional potential of limited treatment side effects.

Highlights

Metastasis is an inefficient process with an estimate of only 0.01% of tumor cells successfully disseminating from a solid tumor and establishing themselves at a distant site [1]
human umbilical vein endothelial cells (HUVECs) were cultured in CloneticsTM endothelial basal medium (EBM)TM supplemented with 2% fetal bovine serum (FBS), penicillin G (10 μg/mL), amphotericin B (25 ng/mL), gentamicin (10 μg/mL), heparin sulfate (0.75 μg/mL), hydrocortisone (1 μg/mL), ascorbic acid (50 μg/mL), insulin growth factor (IGF) (15 ng/mL), vascular endothelial growth factor-A (VEGF-A) (5 ng/mL), epidermal growth factor (EGF) (5 ng/mL), basic fibroblast growth factor (5 ng/mL), and L-glutamine (10 mM) (Lonza, Basel, Switzerland)
RAW 264.7 macrophages yielded a GI50 value of 0.625 ± 0.156 μM with increased sensitivity to 4 Gy radiation (GI50 < 0.039 μM)

Summary

Introduction

Metastasis is an inefficient process with an estimate of only 0.01% of tumor cells successfully disseminating from a solid tumor and establishing themselves at a distant site [1]. Establishment of bone metastatic lesions involves a complex interaction between tumor cells, bone-forming and -resorbing cells, angiogenesis, and mineralized bone matrix to form a supportive microenvironment to foster secondary tumor formation [1,3,4]. Metastasis relies on the migratory and invasive properties of propagating tumor cells to form distant lesions. Undifferentiated tumor cells undergo epithelial–mesenchymal transition (EMT) which is brought about by genetic and epigenetic signaling in the tumor microenvironment [5]. Tumorigenesis and tumor survival depend on the induction of angiogenesis [6,7,8]

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