TY - JOUR

T1 - Implementation of Oxygen Enhanced Magnetic Resonance Imaging (OE-MRI) and a Pilot Genomic Study of Hypoxia in Bladder Cancer Xenografts

AU - Shabbir, Rekaya

AU - Telfer, Brian

AU - Dickie, Ben

AU - Reardon, Mark

AU - Babur, Muhammad

AU - Williams, Kaye

AU - Choudhury, Ananya

AU - West, Catharine

AU - Smith, Tim

N1 - Copyright © 2024, International Institute of Anticancer Research (Dr. George J. Delinasios), All rights reserved.

PY - 2024/6/27

Y1 - 2024/6/27

N2 - BACKGROUND/AIM: Patients with hypoxic bladder cancer benefit from hypoxia modification added to radiotherapy, but no biomarkers exist to identify patients with hypoxic tumours. We, herein, aimed to implement oxygen-enhanced MRI (OE-MRI) in xenografts derived from muscle-invasive bladder cancer (MIBC) for future hypoxia biomarker discovery work; and generate gene expression data for future biomarker discovery.MATERIALS AND METHODS: The flanks of female CD-1 nude mice inoculated with HT1376 MIBC cells. Mice with small (300 mm 3) or large (700 mm 3) tumours were imaged, breathing air then 100% O 2, 1 h post injection with pimonidazole in an Agilant 7T 16cm bore magnet interfaced to a Bruker Avance III console with a T2-TurboRARE sequence using a dynamic MPRAGE acquisition. Dynamic Spoiled Gradient Recalled Echo images were acquired for 5 min, with 0.1mmol/kg Gd-DOTA (Dotarem, Guerbet, UK) injected after 60 s (1 ml/min). Voxel size and field of view of dynamic contrast enhanced (DCE)-MRI and OE-MRI scans were matched. The voxels considered as perfused with significant post-contrast enhancement (p<0.05) in DCE-MRI scans and tissue were further split into pOxyE (normoxic) and pOxyR (hypoxic) regions. Tumours harvested in liquid N 2, sectioned, RNA was extracted and transcriptomes analysed using Clariom S microarrays. RESULTS: Imaged hypoxic regions were greater in the larger versus smaller tumour. Expression of known hypoxia-inducible genes and a 24 gene bladder cancer hypoxia score were higher in pimonidazole-high versus -low regions: CA9 (p=0.012) and SLC2A1 (p=0.012) demonstrating expected transcriptomic behaviour.CONCLUSION: OE-MRI was successfully implemented in MIBC-derived xenografts. Transcriptomic data derived from hypoxic and non-hypoxic xenograft regions will be useful for future studies.

AB - BACKGROUND/AIM: Patients with hypoxic bladder cancer benefit from hypoxia modification added to radiotherapy, but no biomarkers exist to identify patients with hypoxic tumours. We, herein, aimed to implement oxygen-enhanced MRI (OE-MRI) in xenografts derived from muscle-invasive bladder cancer (MIBC) for future hypoxia biomarker discovery work; and generate gene expression data for future biomarker discovery.MATERIALS AND METHODS: The flanks of female CD-1 nude mice inoculated with HT1376 MIBC cells. Mice with small (300 mm 3) or large (700 mm 3) tumours were imaged, breathing air then 100% O 2, 1 h post injection with pimonidazole in an Agilant 7T 16cm bore magnet interfaced to a Bruker Avance III console with a T2-TurboRARE sequence using a dynamic MPRAGE acquisition. Dynamic Spoiled Gradient Recalled Echo images were acquired for 5 min, with 0.1mmol/kg Gd-DOTA (Dotarem, Guerbet, UK) injected after 60 s (1 ml/min). Voxel size and field of view of dynamic contrast enhanced (DCE)-MRI and OE-MRI scans were matched. The voxels considered as perfused with significant post-contrast enhancement (p<0.05) in DCE-MRI scans and tissue were further split into pOxyE (normoxic) and pOxyR (hypoxic) regions. Tumours harvested in liquid N 2, sectioned, RNA was extracted and transcriptomes analysed using Clariom S microarrays. RESULTS: Imaged hypoxic regions were greater in the larger versus smaller tumour. Expression of known hypoxia-inducible genes and a 24 gene bladder cancer hypoxia score were higher in pimonidazole-high versus -low regions: CA9 (p=0.012) and SLC2A1 (p=0.012) demonstrating expected transcriptomic behaviour.CONCLUSION: OE-MRI was successfully implemented in MIBC-derived xenografts. Transcriptomic data derived from hypoxic and non-hypoxic xenograft regions will be useful for future studies.

KW - Animals

KW - Cell Line, Tumor

KW - Female

KW - Genomics/methods

KW - Heterografts

KW - Humans

KW - Hypoxia/diagnostic imaging

KW - Magnetic Resonance Imaging/methods

KW - Mice

KW - Mice, Nude

KW - Oxygen/metabolism

KW - Pilot Projects

KW - Tumor Hypoxia/genetics

KW - Urinary Bladder Neoplasms/genetics

KW - Xenograft Model Antitumor Assays

U2 - 10.21873/cgp.20455

DO - 10.21873/cgp.20455

M3 - Article

C2 - 38944425

VL - 21

SP - 380

EP - 387

JO - Cancer Genomics & Proteomics

JF - Cancer Genomics & Proteomics

IS - 4

ER -