Original ArticlesExosomal transfer of miR-151a enhances chemosensitivity to temozolomide in drug-resistant glioblastoma
Introduction
GBM is a WHO grade IV tumor with a dismal prognosis [1]. The current standard of treatment for GBM patients is surgical resection followed by adjuvant radiation therapy and chemotherapy with TMZ [2]. TMZ is used as a first-line therapy in GBM. However, drug resistance limits the durability of the treatment response.
Exosomes, which are adsorption vesicles of ∼50–120 nm in diameter, are implicated in intercellular communication by transporting intracellular cargos, such as proteins and RNAs [3,4]. The transfer of GBM-released extracellular vesicle (EV) miRNAs to microglia could affect target mRNA and its protein levels in microglia [5]. Intratumoral GBM-released EV miRNAs transfer is also found to augment the heterogeneity of GBM stem-like cells [6]. However, the contribution of GBM exosomal miRNAs to TMZ resistance within the heterogeneous intratumoral ecosystem remains to be elucidated.
The monofunctional DNA-alkylating agent, TMZ exerts its cytotoxic function by inducing DNA damage in GBM cells [7,8]. Damaged bases and nucleotides caused by TMZ could ultimately lead to DNA double-strand breaks (DSBs), resulting in GBM cell death via caspase-dependent apoptotic pathways [7,9,10]. Non-homologous end-joining (NHEJ) is the major pathway by which DSBs are repaired [7,9]. As a vital step in NHEJ process, XRCC4 protein can combine with DNA ligase IV to form the DNA ligase IV/XRCC4 heterodimer and this complex in turn covalently joins the broken DNA ends to help cells survive [7,11]. A possible role of NHEJ pathway in TMZ chemosensitivity has also been reported in GBM cells [7]. Previously, our group has demonstrated that polymorphisms of XRCC4 contribute to glioma susceptibility [12]. XRCC4 expression levels are found significantly downregulated in glioma tissue, indicating crucial roles of XRCC4 in brain carcinogenesis [13]. However, it is still unclear how XRCC4 maintains its oncogenic and TMZ chemoresistant properties in GBMs. Here, we explored the contribution of miR-151a/XRCC4 signaling to TMZ resistance and investigated its therapeutic implications for TMZ-resistant GBM patients.
Our results suggest that exosomes derived from resistant GBM cells could confer drug resistance to sensitive GBM cells. We transfected resistant GBM cells with miR-151a to achieve efficient loading of their exosomes with therapeutic miR-151a. Our data provided strong evidences that loading exogenous miR-151a into exosomes abrogated their ability to confer TMZ resistance to recipient cells and promised therapeutic potential in combination with TMZ chemotherapy. Meanwhile, miR-151a expression of CSF-derived exosomes could also be used as surrogate diagnostic markers for biopsy profiling to predict chemotherapy efficacy in GBM patients.
Section snippets
Patients and samples
Fifteen primary GBM and corresponding recurrent GBM samples from patients who received TMZ treatment (each pair was from the same patient) were obtained from the Chinese Glioma Genome Atlas (CGGA) (patients details in Supplementary Table S1). A total of 156 high-grade glioma (HGG) patients (75 GBMs and 81 Grade III gliomas) who underwent TMZ treatment after receiving surgical resection between January 2010 and December 2016 were from CGGA. Patient information is detailed in the online
miR-151a is lowly expressed in recurrent GBM specimens and TMZ-resistant cells
Our previous analysis of 82 primary glioblastomas have identified that the TMZ chemoresistant subtype (TCR subtype) has poor prognosis [18]. Three top downregulated miRNAs in TCR subtype are let-7i, miR-93 and miR-151a [18].
To obtain TMZ-resistant GBM cells, we grafted U251 and primary GBM N3 cells (N3) into nude mice flanks and performed cycles of TMZ treatment along with serial passage in vivo (Fig. 1A). GBM xenografts from the third passage displayed poor response to TMZ treatment (
Discussion
A strengthened DNA repair mechanism can increase the survival of damaged or mutated tumor cells, resulting in resistance and tumor recurrence [22]. NHEJ plays an important role in tumor cell survival through the acute phase of DNA damage [23,24]. XRCC4, a major participator of NHEJ, has previously been reported to be associated with TMZ resistance [[24], [25], [26]]. However, the mechanism by which its expression is controlled and sustained remains unclear. In our study, we found XRCC4 is a
Funding
This work was supported by a grant from the National Natural Science Foundation of China (No. 81402056 and 81472362), National High Technology Research, Development Program of China (863) (No.2012AA02A508) and National Key Research and Development Plan (No. 2016YFC0902500).
Declarations of interest
None.
Conflicts of interest
None.
References (28)
- et al.
MicroRNA signatures and molecular subtypes of glioblastoma: the role of extracellular transfer
Stem Cell Rep.
(2017) - et al.
DNA double-strand break repair: from mechanistic understanding to cancer treatment
DNA Repair
(2007) - et al.
Mechanisms of human DNA repair: an update
Toxicology
(2003) - et al.
Recombination at double-strand breaks and DNA ends: conserved mechanisms from phage to humans
Mol. Cell
(2001) - et al.
IDH1/2 mutation status combined with Ki-67 labeling index defines distinct prognostic groups in glioma
Oncotarget
(2015) - et al.
Radiotherapy plus concomitant and adjuvant temozolomide for glioblastoma
N. Engl. J. Med.
(2005) - et al.
Exosomes in cancer development, metastasis, and drug resistance: a comprehensive review
Canc. Metastasis Rev.
(2013) - et al.
Tumour exosomes from cells harbouring PTPRZ1-MET fusion contribute to a malignant phenotype and temozolomide chemoresistance in glioblastoma
Oncogene
(2017) - et al.
Directly visualized glioblastoma-derived extracellular vesicles transfer RNA to microglia/macrophages in the brain
Neuro Oncol.
(2016) - et al.
Complex DNA repair pathways as possible therapeutic targets to overcome temozolomide resistance in glioblastoma
Front. Oncol.
(2012)
The DNA damage response: implications for tumor responses to radiation and chemotherapy
Annu. Rev. Med.
Homologous recombination in cancer development, treatment and development of drug resistance
Carcinogenesis
The DNA damage response: implications for tumor responses to radiation and chemotherapy
Annu. Rev. Med.
Genetic polymorphisms of DNA double-strand break repair pathway genes and glioma susceptibility
BMC Canc.
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