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The failure of DAC to induce OCT2 expression and its remission by hemoglobin-based nanocarriers under hypoxia in renal cell carcinoma
- Source :
- Theranostics
- Publication Year :
- 2019
-
Abstract
- Background: Human organic cation transporter 2 (OCT2) is the most abundant and important uptake transporter involved in the renal excretion of cationic drugs. Abnormal hypermethylation- mediated silencing of OCT2 results in oxaliplatin resistance in renal cell carcinoma (RCC). The epigenetic activation of OCT2 by decitabine (DAC) reversed this resistance in normoxic conditions. Given the hypoxic characteristic of RCC, it is still unclear whether hypoxia promotes DAC resistance and is involved in the regulation of OCT2. Methods: The mRNA and protein expression of OCT2 was determined by qRT-PCR and Western blotting. MSRE-qPCR and BSP were used to examine methylation modifications at the OCT2 promoter. The ChIP-qPCR analysis was performed to detect the abundance of histone modification and HIF-1α. The accumulation of DAC and 5-mC were detected using LC-MS, and the amount of 5-hmC was determined by dot blot analysis. To understand the role of hypoxia in the regulation of equilibrative nucleoside transporter 1 (ENT1) expression, the HIF-1α KO cell model was constructed. The re-emulsion method was used for the construction of H-NPs, an oxygen nanocarrier based on hemoglobin, to alleviate the drug resistance of DAC under hypoxia. Results: DAC was unable to upregulate OCT2 expression in hypoxic conditions because of the hypermethylation and low H3K4me3 modification in its promoter region. Hypoxia-mediated repression of human ENT1, which was markedly suppressed in RCC, resulted in a decrease in the cellular accumulation of DAC. Besides, hypoxia-induced upregulation of histone deacetylase HDAC9, which impaired the enrichment of H3K27ac modification in the OCT2 promoter, led to the transcriptional repression of OCT2. H-NPs could attenuate the hypoxia-induced loss of DAC activity and sensitize RCC cells to the sequential combination therapy of DAC and oxaliplatin. Conclusions: Hypoxia-mediated repression of ENT1 led to the inability of DAC to upregulate the expression of OCT2 under hypoxia. H-NPs could alleviate resistance to oxaliplatin and DAC in RCC cells under hypoxia and may have potential clinical applications.
- Subjects :
- 0301 basic medicine
Epigenomics
Male
Medicine (miscellaneous)
Equilibrative nucleoside transporter 1
OCT2
Histones
Hemoglobins
Mice
0302 clinical medicine
Hypoxia
Promoter Regions, Genetic
Pharmacology, Toxicology and Pharmaceutics (miscellaneous)
Mice, Inbred BALB C
biology
Chemistry
Organic Cation Transporter 2
Kidney Neoplasms
Up-Regulation
Blot
Oxaliplatin
030220 oncology & carcinogenesis
DNA methylation
medicine.symptom
ENT1
Research Paper
Antimetabolites, Antineoplastic
renal cell carcinoma
Antineoplastic Agents
Decitabine
Histone Deacetylases
Equilibrative Nucleoside Transporter 1
03 medical and health sciences
Downregulation and upregulation
medicine
Gene silencing
Animals
Humans
RNA, Messenger
Carcinoma, Renal Cell
HDAC9
Hypoxia (medical)
DNA Methylation
Hypoxia-Inducible Factor 1, alpha Subunit
Repressor Proteins
030104 developmental biology
Drug Resistance, Neoplasm
biology.protein
Cancer research
Nanoparticles
Histone deacetylase
Subjects
Details
- ISSN :
- 18387640
- Volume :
- 10
- Issue :
- 8
- Database :
- OpenAIRE
- Journal :
- Theranostics
- Accession number :
- edsair.doi.dedup.....00b6d7fb0bf77402a4466531b2599ebc