Differential Expression of miRNAs in Hypoxia ("HypoxamiRs") in Three Canine High-Grade Glioma Cell Lines.

Jennifer Koehler,Shawn A Levy,Maninder Sandey,Xiaozhu Wang,Xu Wang,Nripesh Prasad

doi:10.3389/fvets.2020.00104

Abstract

Dogs with spontaneous high-grade gliomas increasingly are being proposed as useful large animal pre-clinical models for the human disease. Hypoxia is a critical microenvironmental condition that is common in both canine and human high-grade gliomas and drives increased angiogenesis, chemo- and radioresistance, and acquisition of a stem-like phenotype. Some of this effect is mediated by the hypoxia-induced expression of microRNAs, small (~22 nucleotides long), non-coding RNAs that can modulate gene expression through interference with mRNA translation. Using an in vitro model with three canine high-grade glioma cell lines (J3T, SDT3G, and G06A) exposed to 72 h of 1.5% oxygen vs. standard 20% oxygen, we examined the global “hypoxamiR” profile using small RNA-Seq and performed pathway analysis for targeted genes using both Panther and NetworkAnalyst. Important pathways include many that are well-established as being important in glioma biology, general cancer biology, hypoxia, angiogenesis, immunology, and stem-ness, among others. This work provides the first examination of the effect of hypoxia on miRNA expression in the context of canine glioma, and highlights important similarities with the human disease.

Highlights

Glioblastomas are malignant primary brain tumors that comprise ∼1/5 of all primary brain tumors in adult humans and are associated with a rapid clinical decline and short survival time after diagnosis, with or without treatment [1]
When examining the target gene set from the 21 miRNAs differentially expressed in all three cell lines using the Panther tool, the highest number of hits were in the Wnt signaling pathway, followed by the pathways listed in Table 1 and in Supplemental Table 2, many of which are known to be involved in cancer biology, progression, metastasis, or acquisition or maintenance of a stem-like phenotype
Because there is some degree of bias inherent in any pathwayprediction database, predicted gene targets for miRNAs that were differentially upregulated in all three cell lines were analyzed for involvement in specific pathways using NetworkAnalyst, including miR-1-3p, miR-122-5p, miR-134-5p, miR-1835p, miR-193a-5p, miR-204-5p, miR-210-3p, miR-215-5p, of a single manuscript, for the purposes of discussion we have chosen to present a brief overview of some of the most highly differentially regulated miRNAs and those that may be relevant from a comparative cancer biology or therapeutic targeting perspective

Summary

Introduction

Glioblastomas are malignant primary brain tumors that comprise ∼1/5 of all primary brain tumors in adult humans and are associated with a rapid clinical decline and short survival time after diagnosis, with or without treatment [1]. Canine patients suffer from malignant gliomas, with tumors that are largely similar in histopathological appearance, clinical progression, and some key molecular features [2,3,4,5]. Canine Glioma Hypoxia-Induced miRNAs mutation-induced genetic heterogeneity and methylation patterns, as well as regional phenotypic differences secondary to microenvironmental influences such as oxygen level, pH, and extracellular matrix stiffness [13,14,15,16,17]. Hypoxia secondary to ineffective tumor vascularization and tissue infarction is common in both human and canine high-grade gliomas, and is an extremely important driver of tumor growth, invasiveness, chemo- and radioresistance, and acquisition of a stem-like phenotype [18,19,20,21,22]

Methods

Results

Conclusion