ABSTRACT
MicroRNAs (miRNAs) are short, noncoding RNAs that regulate gene expression by suppressing mRNA translation and reducing mRNA stability. A miRNA can potentially bind many mRNAs, thereby affecting the expression of oncogenes and tumor suppressor genes as well as the activity of whole pathways. The promise of miRNA therapeutics in cancer is to harness this evolutionarily conserved mechanism for the coordinated regulation of gene expression, and thus restoring a normal cell phenotype. However, the promiscuous binding of miRNAs can provoke unwanted off-target effects, which are usually caused by high-dose single-miRNA treatments. Thus, it is desirable to develop miRNA therapeutics with increased specificity and efficacy. To achieve that, we propose the concept of miRNA cooperativity in order to exert synergistic repression on target genes, thus lowering the required total amount of miRNAs. We first review miRNA therapies in clinical application. Next, we summarize the knowledge on the molecular mechanism and biological function of miRNA cooperativity and discuss its application in cancer therapies. We then propose and discuss a systems biology approach to investigate miRNA cooperativity for the clinical setting. Altogether, we point out the potential of miRNA cooperativity to reduce off-target effects and to complement conventional, targeted, or immune-based therapies for cancer.
Subject(s)
Antineoplastic Agents/therapeutic use , Gene Expression Regulation, Neoplastic , MicroRNAs/genetics , Neoplasms/therapy , RNA, Neoplasm/genetics , Systems Biology/methods , Antagomirs/genetics , Antagomirs/metabolism , Antineoplastic Agents/chemistry , Antineoplastic Agents/metabolism , Apoptosis/drug effects , Apoptosis/genetics , Chemotherapy, Adjuvant/methods , Gene Regulatory Networks , Humans , MicroRNAs/agonists , MicroRNAs/antagonists & inhibitors , MicroRNAs/metabolism , Neoplasms/genetics , Neoplasms/metabolism , Neoplasms/pathology , Oligoribonucleotides/genetics , Oligoribonucleotides/metabolism , RNA Stability , RNA, Messenger/genetics , RNA, Messenger/metabolism , RNA, Neoplasm/agonists , RNA, Neoplasm/antagonists & inhibitors , RNA, Neoplasm/metabolism , Small Molecule Libraries/therapeutic use , Tumor Suppressor Proteins/agonists , Tumor Suppressor Proteins/genetics , Tumor Suppressor Proteins/metabolismABSTRACT
Although dexamethasone (DEX) remains a first-line agent for multiple myeloma (MM) therapy, the development of DEX resistance has become an indicator of poor prognosis in MM patients. It is thus urgent to develop strategies to restore the vulnerability of MM to DEX. This study demonstrated long non-coding RNA (lncRNA) nuclear paraspeckle assembly transcript 1 (NEAT1) was highly expressed in DEX-resistant myeloma cell lines, and upregulation of NEAT1 was tightly linked to poor prognosis. The in-depth study revealed that during the development of DEX resistance in these cells, the miR-193a levels were decreased, which resulted in the increased expression of the target gene myeloid cell leukemia-1 (MCL1). We also found knockdown of NEAT1, the DEX-induced sensitivity was enhanced in the resistant cells. Meanwhile, overexpression of NEAT1 increased the DEX-induced resistance in the sensitive cells. In conclusion, the NEAT1/miR-193a/MCL1 pathway is closely associated with the development of DEX resistance in myeloma cells, and knockdown of NEAT1 can significantly improve DEX sensitivity in MM.
Subject(s)
Dexamethasone/therapeutic use , Drug Resistance, Neoplasm , MicroRNAs/antagonists & inhibitors , Multiple Myeloma/drug therapy , Myeloid Cell Leukemia Sequence 1 Protein/antagonists & inhibitors , RNA, Long Noncoding/metabolism , Signal Transduction/drug effects , Antineoplastic Agents, Hormonal/pharmacology , Antineoplastic Agents, Hormonal/therapeutic use , Apoptosis/drug effects , Cell Line, Tumor , Dexamethasone/pharmacology , Female , Gene Expression Regulation, Neoplastic/drug effects , Humans , Male , MicroRNAs/metabolism , Middle Aged , Multiple Myeloma/diagnosis , Multiple Myeloma/metabolism , Multiple Myeloma/pathology , Mutation , Myeloid Cell Leukemia Sequence 1 Protein/agonists , Myeloid Cell Leukemia Sequence 1 Protein/genetics , Myeloid Cell Leukemia Sequence 1 Protein/metabolism , Neoplasm Staging , Prognosis , RNA/agonists , RNA/antagonists & inhibitors , RNA/metabolism , RNA Interference , RNA, Long Noncoding/agonists , RNA, Long Noncoding/antagonists & inhibitors , RNA, Neoplasm/agonists , RNA, Neoplasm/antagonists & inhibitors , RNA, Neoplasm/metabolism , Recombinant Proteins/chemistry , Recombinant Proteins/metabolism , Survival AnalysisABSTRACT
Tamoxifen-resistant (TAMR) estrogen receptor-positive (ER+) breast cancer is characterized by elevated Erb-B2 receptor tyrosine kinase 2 (ERBB2) expression. However, the underlying mechanisms responsible for the increased ERBB2 expression in the TAMR cells remain poorly understood. Herein, we reported that the ERBB2 expression is regulated at the post-transcriptional level by miR26a/b and the RNA-binding protein human antigen R (HuR), both of which associate with the 3'-UTR of the ERBB2 transcripts. We demonstrated that miR26a/b inhibits the translation of ERBB2 mRNA, whereas HuR enhances the stability of the ERBB2 mRNA. In TAMR ER+ breast cancer cells with elevated ERBB2 expression, we observed a decrease in the level of miR26a/b and an increase in the level of HuR. The forced expression of miR26a/b or the depletion of HuR decreased ERBB2 expression in the TAMR cells, resulting in the reversal of tamoxifen resistance. In contrast, the inactivation of miR26a/b or forced expression of HuR decreased tamoxifen responsiveness of the parental ER+ breast cancer cells. We further showed that the increase in HuR expression in the TAMR ER+ breast cancer cells is attributable to an increase in the HuR mRNA isoform with shortened 3'-UTR, which exhibits increased translational activity. This shortening of the HuR mRNA 3'-UTR via alternative polyadenylation (APA) was observed to be dependent on cleavage stimulation factor subunit 2 (CSTF2/CstF-64), which is up-regulated in the TAMR breast cancer cells. Taken together, we have characterized a model in which the interplay between miR26a/b and HuR post-transcriptionally up-regulates ERBB2 expression in TAMR ER+ breast cancer cells.
Subject(s)
3' Untranslated Regions/drug effects , Breast Neoplasms/drug therapy , Drug Resistance, Neoplasm , ELAV-Like Protein 1/metabolism , MicroRNAs/metabolism , Receptor, ErbB-2/metabolism , Tamoxifen/pharmacology , Antineoplastic Agents, Hormonal/pharmacology , Breast Neoplasms/metabolism , Breast Neoplasms/pathology , Cell Line, Tumor , Cell Proliferation/drug effects , Cleavage Stimulation Factor , Female , Humans , MicroRNAs/antagonists & inhibitors , Mutation , Neoplasm Proteins/agonists , Neoplasm Proteins/antagonists & inhibitors , Neoplasm Proteins/genetics , Neoplasm Proteins/metabolism , Polyadenylation/drug effects , RNA Interference , RNA Stability/drug effects , RNA, Messenger/agonists , RNA, Messenger/antagonists & inhibitors , RNA, Messenger/chemistry , RNA, Messenger/metabolism , RNA, Neoplasm/agonists , RNA, Neoplasm/antagonists & inhibitors , RNA, Neoplasm/chemistry , RNA, Neoplasm/metabolism , RNA-Binding Proteins/agonists , RNA-Binding Proteins/genetics , RNA-Binding Proteins/metabolism , Receptor, ErbB-2/agonists , Receptor, ErbB-2/antagonists & inhibitors , Receptor, ErbB-2/genetics , Response Elements/drug effects , Up-Regulation/drug effectsABSTRACT
Trichloroethylene (TCE), commonly used as an industrial solvent, is ubiquitous in our living environment. TCE exposure can induce hepatocellular carcinoma (HCC) in mice, but the underlying mechanisms remain elusive. To understand the role of miRNA in the hepatocarcinogenesis of TCE, we examined the miRNA expression profiles by microarray in the liver of B6C3F1 male mice exposed to TCE at 0 or 1000 mg/kg b.w. Nine differentially expressed miRNAs were identified, out of which miR-182-5p exhibited the highest increase in expression. Moreover, the TCE-induced upregulation of miR182-5p in mouse liver was dose dependent and correlated with promoter DNA hypomethylation. Treatment of mouse liver cell lines (BNL CL.2 and Hepa1-6) with TCE at non-toxic doses (0.1 and/or 0.3 mM) significantly increased the expression level of miR-182-5p accompanied with elevated cell proliferation. The TCE-induced cell proliferation was further found to be mediated by miR-182-5p overexpression. Additionally, tumor suppressor gene Cited2, which was downregulated in TCE exposed mouse liver cells, was proved to be a direct target of miR-182-5p. In conclusion, TCE might up-regulate miR-182-5p expression by DNA hypomethylation, which could suppress Cited2 and improve cell proliferation rate, resulting in liver tumor.
Subject(s)
Carcinogenesis/drug effects , Carcinogens/toxicity , Carcinoma, Hepatocellular/chemically induced , Liver/drug effects , MicroRNAs/agonists , Repressor Proteins/antagonists & inhibitors , Trans-Activators/antagonists & inhibitors , Trichloroethylene/toxicity , Animals , Carcinoma, Hepatocellular/metabolism , Carcinoma, Hepatocellular/pathology , Cell Line , Cell Line, Tumor , Cell Proliferation/drug effects , Crosses, Genetic , DNA Methylation/drug effects , Gene Expression Regulation, Neoplastic/drug effects , Genes, Reporter/drug effects , Humans , Liver/metabolism , Liver/pathology , Liver Neoplasms/chemically induced , Liver Neoplasms/metabolism , Liver Neoplasms/pathology , Male , Mice , MicroRNAs/metabolism , Neoplasm Proteins/antagonists & inhibitors , Neoplasm Proteins/genetics , Neoplasm Proteins/metabolism , Promoter Regions, Genetic/drug effects , RNA, Neoplasm/agonists , RNA, Neoplasm/metabolism , Random Allocation , Repressor Proteins/genetics , Repressor Proteins/metabolism , Solvents/toxicity , Trans-Activators/genetics , Trans-Activators/metabolismABSTRACT
BACKGROUND AND PURPOSE: Gambogic acid (GA) and methyl jasmonate (MJ) are increasingly being recognized as novel natural anticancer compounds. Here, we investigated the antitumour effects of GA in combination with MJ on human bladder cancer cells. EXPERIMENTAL APPROACH: Cell viability was detected by cell counting kit-8 assay. Cell apoptosis was assessed by Hoechst 33258 staining and flow cytometry. Protein levels were determined by immunoblotting and expressions of mRNA and miRNAs by RT-PCR. Differential expressions of a group of downstream genes were identified using microarray analysis. KEY RESULTS: MJ significantly sensitized bladder cancer cells to GA-induced growth inhibition and apoptosis while sparing normal fibroblasts. MJ enhanced GA-induced activation of caspase-3 and caspase-9, and down-regulated the expression of XIAP. Furthermore, treatment of bladder cancer cells with a combination of GA and MJ induced synergistic inhibition of the enhancer of zeste homologue 2 (EZH2) expression, whereas miR-101 expression was up-regulated. Conversely, knockdown of miR-101 restored this decreased expression of EZH2 and suppressed the inhibitory effect of GA and MJ on the growth of bladder cancer cells. Microarray analysis showed that genes closely associated with bladder cancer development were significantly down-regulated by GA and MJ. In a s.c. xenograft mouse model of human bladder carcinoma, the combination of GA and MJ exerted an increased antitumour effect compared with GA alone. CONCLUSION AND IMPLICATIONS: MJ sensitizes bladder cancer cells to GA-induced apoptosis by down-regulating the expression of EZH2 induced by miR-101. Thus, the combination of selective anti-cancer agents MJ and GA could provide a novel strategy for treating human bladder cancer.
