The tumor suppressor p53 is one of the most frequently mutated genes in human cancers. MicroRNAs (miRNAs) are small non-protein coding RNAs that regulate gene expression on the post-transcriptional level. Recently, ...The tumor suppressor p53 is one of the most frequently mutated genes in human cancers. MicroRNAs (miRNAs) are small non-protein coding RNAs that regulate gene expression on the post-transcriptional level. Recently, it was shown that p53 regulates the expression of several miRNAs, thereby representing an important mechanism of p53 signaling. Several independent studies identified the members of the miR-34 family as the most prevalent p53-induced miRNAs, miR-34s are frequently silenced in variety of tumor entities, suggesting that they are important tumor suppressors. Indeed, ectopic expression of miR-34s inhibits proliferation, epithelial to mes- enchymat transition, migration, invasion, and metastasis of various cancer celt entities. Moreover, delivery or re-expression of miR-34 leads to notable repression of tumor growth and metastasis in cancer mouse models, and may therefore represent an efficient strategy for future cancer therapeutics. Besides their crucial functions in cancer, members of the miR-34 family also play important roles in spermatogenesis, stem cell differentiation, neuronal development, aging, and cardiovascular functions. Consequently, miR-34 has also been implicated in various non-cancerous diseases, such as brain disorders, osteoporosis, and cardiovascular complications.展开更多
AIM To investigate micro(mi)R-34 a-antagonizing circular(circ)RNA that underlies hepatocellular steatosis.METHODS The effect of circ RNA on mi R-34 a was recognized by the mi RNA response element(MRE), and validated b...AIM To investigate micro(mi)R-34 a-antagonizing circular(circ)RNA that underlies hepatocellular steatosis.METHODS The effect of circ RNA on mi R-34 a was recognized by the mi RNA response element(MRE), and validated by the dual-luciferase reporter assay. Its association with hepatocellular steatosis was investigated in Hep G2-based hepatocellular steatosis induced by free fatty acids(FFAs; 2:1 oleate:palmitate) stimulation. After normalization of the steatosis-related circRNA by expression vector, analysis of mi R-34 a activity,peroxisome proliferator-activated receptor(PPAR)α level, and expression of downstream genes were carried out so as to reveal its impact on the mi R-34 a/PPARα regulatory system. Both triglyceride(TG) assessment and cytopathological manifestations uncovered the role of circRNA in miR-34 a-dependent hepatosteatogenesis.RESULTS Bioinformatic and functional analysis verified circRNA_0046366 to antagonize the activity of mi R-34 a via MRE-based complementation. In contrast to its lowered level during FFA-induced hepatocellular steatosis, circ RNA_0046366 up-regulation abolished the mi R-34 a-dependent inhibition of PPARα that played a critical role in metabolic signaling pathways. PPARα restoration exerted transcriptional improvement to multiple genes responsible for lipid metabolism. TGspecific lipolytic genes [carnitine palmitoyltransferase 1 A(CPT1 A) and solute-carrier family 27 A(SLC27 A)] among these showed significant increase in their expression levels. The circ RNA_0046366-related rebalancing of lipid homeostasis led to dramatic reduction of TG content, and resulted in the ameliorated phenotype of hepatocellular steatosis.CONCLUSION Dysregulation of circ RNA_0046366/mi R-34 a/PPARα signaling may be a novel epigenetic mechanism underlying hepatocellular steatosis. circ RNA_0046366 serves as a potential target for the treatment of hepatic steatosis.展开更多
To investigate whether microRNA (miR)-34a mediates oxaliplatin (OXA) resistance of colorectal cancer (CRC) cells by inhibiting macroautophagy via the transforming growth factor (TGF)-β/Smad4 pathway.METHODSmiR-34a ex...To investigate whether microRNA (miR)-34a mediates oxaliplatin (OXA) resistance of colorectal cancer (CRC) cells by inhibiting macroautophagy via the transforming growth factor (TGF)-β/Smad4 pathway.METHODSmiR-34a expression levels were detected in CRC tissues and CRC cell lines by quantitative real-time polymerase chain reaction. Computational search, functional luciferase assay and western blotting were used to demonstrate the downstream target of miR-34a in CRC cells. Cell viability was measured with Cell Counting Kit-8. Apoptosis and macroautophagy of CRC cells were analyzed by flow cytometry and transmission electron microscopy, and expression of beclin I and LC3-II was detected by western blotting.RESULTSExpression of miR-34a was significantly reduced while expression of TGF-β and Smad4 was increased in CRC patients treated with OXA-based chemotherapy. OXA treatment also resulted in decreased miR-34a levels and increased TGF-β and Smad4 levels in both parental cells and the OXA-resistant CRC cells. Activation of macroautophagy contributed to OXA resistance in CRC cells. Expression levels of Smad4 and miR-34a in CRC patients had a significant inverse correlation and overexpressing miR-34a inhibited macroautophagy activation by directly targeting Smad4 through the TGF-β/Smad4 pathway. OXA-induced downregulation of miR-34a and increased drug resistance by activating macroautophagy in CRC cells.CONCLUSIONmiR-34a mediates OXA resistance of CRC by inhibiting macroautophagy via the TGF-β/Smad4 pathway.展开更多
文摘The tumor suppressor p53 is one of the most frequently mutated genes in human cancers. MicroRNAs (miRNAs) are small non-protein coding RNAs that regulate gene expression on the post-transcriptional level. Recently, it was shown that p53 regulates the expression of several miRNAs, thereby representing an important mechanism of p53 signaling. Several independent studies identified the members of the miR-34 family as the most prevalent p53-induced miRNAs, miR-34s are frequently silenced in variety of tumor entities, suggesting that they are important tumor suppressors. Indeed, ectopic expression of miR-34s inhibits proliferation, epithelial to mes- enchymat transition, migration, invasion, and metastasis of various cancer celt entities. Moreover, delivery or re-expression of miR-34 leads to notable repression of tumor growth and metastasis in cancer mouse models, and may therefore represent an efficient strategy for future cancer therapeutics. Besides their crucial functions in cancer, members of the miR-34 family also play important roles in spermatogenesis, stem cell differentiation, neuronal development, aging, and cardiovascular functions. Consequently, miR-34 has also been implicated in various non-cancerous diseases, such as brain disorders, osteoporosis, and cardiovascular complications.
基金National Key Research and Development Plan‘Precision Medicine Research’,No.2017YFSF090203National Natural Science Foundation of China,No.81070346,No.81270492,No.81470859,No.81270491 and No.81470840+2 种基金State Key Development Program for Basic Research of China,No.2012CB517501100 Talents Program,No.XBR2011007hProgram of the Committee of Science and Technology,No.09140903500
文摘AIM To investigate micro(mi)R-34 a-antagonizing circular(circ)RNA that underlies hepatocellular steatosis.METHODS The effect of circ RNA on mi R-34 a was recognized by the mi RNA response element(MRE), and validated by the dual-luciferase reporter assay. Its association with hepatocellular steatosis was investigated in Hep G2-based hepatocellular steatosis induced by free fatty acids(FFAs; 2:1 oleate:palmitate) stimulation. After normalization of the steatosis-related circRNA by expression vector, analysis of mi R-34 a activity,peroxisome proliferator-activated receptor(PPAR)α level, and expression of downstream genes were carried out so as to reveal its impact on the mi R-34 a/PPARα regulatory system. Both triglyceride(TG) assessment and cytopathological manifestations uncovered the role of circRNA in miR-34 a-dependent hepatosteatogenesis.RESULTS Bioinformatic and functional analysis verified circRNA_0046366 to antagonize the activity of mi R-34 a via MRE-based complementation. In contrast to its lowered level during FFA-induced hepatocellular steatosis, circ RNA_0046366 up-regulation abolished the mi R-34 a-dependent inhibition of PPARα that played a critical role in metabolic signaling pathways. PPARα restoration exerted transcriptional improvement to multiple genes responsible for lipid metabolism. TGspecific lipolytic genes [carnitine palmitoyltransferase 1 A(CPT1 A) and solute-carrier family 27 A(SLC27 A)] among these showed significant increase in their expression levels. The circ RNA_0046366-related rebalancing of lipid homeostasis led to dramatic reduction of TG content, and resulted in the ameliorated phenotype of hepatocellular steatosis.CONCLUSION Dysregulation of circ RNA_0046366/mi R-34 a/PPARα signaling may be a novel epigenetic mechanism underlying hepatocellular steatosis. circ RNA_0046366 serves as a potential target for the treatment of hepatic steatosis.
基金Supported by Science Foundation of Education Department of Heilongjiang Province,China,no.12541430
文摘To investigate whether microRNA (miR)-34a mediates oxaliplatin (OXA) resistance of colorectal cancer (CRC) cells by inhibiting macroautophagy via the transforming growth factor (TGF)-β/Smad4 pathway.METHODSmiR-34a expression levels were detected in CRC tissues and CRC cell lines by quantitative real-time polymerase chain reaction. Computational search, functional luciferase assay and western blotting were used to demonstrate the downstream target of miR-34a in CRC cells. Cell viability was measured with Cell Counting Kit-8. Apoptosis and macroautophagy of CRC cells were analyzed by flow cytometry and transmission electron microscopy, and expression of beclin I and LC3-II was detected by western blotting.RESULTSExpression of miR-34a was significantly reduced while expression of TGF-β and Smad4 was increased in CRC patients treated with OXA-based chemotherapy. OXA treatment also resulted in decreased miR-34a levels and increased TGF-β and Smad4 levels in both parental cells and the OXA-resistant CRC cells. Activation of macroautophagy contributed to OXA resistance in CRC cells. Expression levels of Smad4 and miR-34a in CRC patients had a significant inverse correlation and overexpressing miR-34a inhibited macroautophagy activation by directly targeting Smad4 through the TGF-β/Smad4 pathway. OXA-induced downregulation of miR-34a and increased drug resistance by activating macroautophagy in CRC cells.CONCLUSIONmiR-34a mediates OXA resistance of CRC by inhibiting macroautophagy via the TGF-β/Smad4 pathway.