ABSTRACT
Programmed cell death 4 (PDCD4), as a tumor suppressor gene, is frequently reduced in a variety of tumors, including gastric cancer. Previous findings have indicated that PDCD4 participates in tumorigenesis through the regulation of apoptosis, but the molecular basis of this process has not been fully elucidated, and no studies have shown the upstream regulation of this gene in gastric cancer. In this study, we used bioinformatics analysis to search for miRNAs that could potentially target PDCD4 and identified miR-93 as a candidate. Moreover, we observed the inverse correlation between miR-93 and PDCD4 protein levels, but not mRNA levels, in human gastric cancer tissues. We further experimentally validated PDCD4 as the direct target of miR-93 by evaluating PDCD4 expression in gastric cancer cells after the overexpression or knockdown of miR-93. Additionally, the biological consequences of targeting PDCD4 through miR-93 were examined using cell apoptosis assays in vitro. We demonstrated that the repression of PDCD4 through miR-93 suppressed the apoptosis of gastric cancer cells. Finally, we revealed that miR-93 promoted the development of gastric tumor growth in xenograft mice by negatively regulating PDCD4. Taken together, the findings of the present study indicated the oncogenic role of miR-93 in gastric cancer tumorigenesis through targeting PDCD4, particularly in apoptosis.
Subject(s)
Apoptosis Regulatory Proteins/genetics , Down-Regulation , MicroRNAs/genetics , RNA-Binding Proteins/genetics , Stomach Neoplasms/genetics , 3' Untranslated Regions/genetics , Animals , Apoptosis/genetics , Apoptosis Regulatory Proteins/metabolism , Blotting, Western , Cell Line, Tumor , Gene Expression Profiling/methods , Gene Expression Regulation, Neoplastic , Humans , Male , Mice, SCID , Oncogenes/genetics , RNA Interference , RNA-Binding Proteins/metabolism , Reverse Transcriptase Polymerase Chain Reaction , Stomach Neoplasms/metabolism , Stomach Neoplasms/pathology , Transplantation, Heterologous , Tumor Burden/geneticsABSTRACT
Cell-derived exosomes have been demonstrated to be efficient carriers of small RNAs to neighbouring or distant cells, highlighting the preponderance of exosomes as carriers for gene therapy over other artificial delivery tools. In the present study, we employed modified exosomes expressing the neuron-specific rabies viral glycoprotein (RVG) peptide on the membrane surface to deliver opioid receptor mu (MOR) siRNA into the brain to treat morphine addiction. We found that MOR siRNA could be efficiently packaged into RVG exosomes and was associated with argonaute 2 (AGO2) in exosomes. These exosomes efficiently and specifically delivered MOR siRNA into Neuro2A cells and the mouse brain. Functionally, siRNA-loaded RVG exosomes significantly reduced MOR mRNA and protein levels. Surprisingly, MOR siRNA delivered by the RVG exosomes strongly inhibited morphine relapse via the down-regulation of MOR expression levels. In conclusion, our results demonstrate that targeted RVG exosomes can efficiently transfer siRNA to the central nervous system and mediate the treatment of morphine relapse by down-regulating MOR expression levels. Our study provides a brand new strategy to treat drug relapse and diseases of the central nervous system.
