ABSTRACT
Deregulated microRNAs (miRNAs) are small noncoding RNAs that are involved in the carcinogenesis of various cancers, including lung cancer. HIF1a has been suggested to be a master regulator of hypoxia-induced cell proliferation. The relationship between HIF1a expression and the progression of non-small cell lung cancer (NSCLC) is not fully understood, and whether HIF1a expression is regulated by miRNAs in this process remains unclear. In this study, we found that the upregulation of HIF1a expression and the reduction in miR-199a levels were highly associated with NSCLC progression. NSCLC cells derived from cancer tissues with low miR-199a levels showed high HIF1a expression and high proliferation capacity. Moreover, HIF1a and glycolysis inhibitors suppress the proliferation of NSCLC cells. MiR-199a overexpression suppressed the hypoxia-induced proliferation of NSCLC cells through targeting elevated HIF1a and blocking the downstream upregulation of PDK1 without affecting AKT activation. Together, these results indicate that downregulation of miR-199a is essential for hypoxia-induced proliferation through derepressing the expression of HIF1a expression and affecting HIF1a mediated glycolytic pathway in NSCLC progression.
Subject(s)
Carcinoma, Non-Small-Cell Lung/genetics , Cell Hypoxia/genetics , Hypoxia-Inducible Factor 1, alpha Subunit/metabolism , Lung Neoplasms/genetics , MicroRNAs/genetics , Cell Line, Tumor , Cell Proliferation , Glycolysis/genetics , Humans , Hypoxia-Inducible Factor 1, alpha Subunit/genetics , MicroRNAs/metabolism , Protein Serine-Threonine Kinases/biosynthesis , Proto-Oncogene Proteins c-akt/metabolism , Pyruvate Dehydrogenase Acetyl-Transferring Kinase , Up-RegulationABSTRACT
The ATR-ATRIP protein kinase complex plays a crucial role in the cellular response to replication stress and DNA damage. Recent studies found that ATR could be activated in response to hypoxia and be involved in hypoxia-induced genetic instability in cancer cells. However, the underlying mechanisms for ATR activation in response to hypoxic stress are still not fully understood. We reported that ATRIP is a direct target of HIF-1. Silencing the expression of HIF-1α in cancer cells by RNA interference abolished hypoxia-induced ATRIP expression. Silencing the expression of ATRIP by RNA interference abolished hypoxia induced ATR activation and CHK1 phosphorylation in cancer cells. Taken together, these data shed novel insights on the mechanism of hypoxia-induced activation of the ATR pathway.
Subject(s)
Adaptor Proteins, Signal Transducing/genetics , Cell Cycle Proteins/genetics , DNA-Binding Proteins/genetics , Hypoxia-Inducible Factor 1, alpha Subunit/genetics , Protein Serine-Threonine Kinases/genetics , Adaptor Proteins, Signal Transducing/metabolism , Ataxia Telangiectasia Mutated Proteins , Binding Sites/genetics , Blotting, Western , Cell Cycle Proteins/metabolism , Cell Hypoxia , Cell Line , Checkpoint Kinase 1 , Chromatin Immunoprecipitation , DNA-Binding Proteins/metabolism , Gene Expression Regulation, Neoplastic , HEK293 Cells , HeLa Cells , Hep G2 Cells , Humans , Hypoxia-Inducible Factor 1, alpha Subunit/metabolism , MCF-7 Cells , Neoplasms/genetics , Neoplasms/metabolism , Neoplasms/pathology , Phosphorylation , Promoter Regions, Genetic/genetics , Protein Binding , Protein Kinases/metabolism , Protein Serine-Threonine Kinases/metabolism , RNA Interference , Response Elements/genetics , Reverse Transcriptase Polymerase Chain ReactionABSTRACT
Hepatocellular carcinoma (HCC) is the most common type of liver cancer. HDAC6 is a transcriptional regulator of the histone deacetylase family, subfamily 2. Previous studies have shown that HDAC6 plays critical roles in transcription regulation, cell cycle progression and developmental events. However, its biological roles in the development of HCC remain largely unexplored. In the present study, we found that mRNA and protein levels of HDAC6 were up-regulated in HCC tissues and cell lines. The proinflammatory cytokines, which were up-regulated in the human HCC microenvironment, increased HDAC6 expression through a proximal NF-kappaB binding site on the HDAC6 gene promoter. Furthermore, overexpression of HDAC6 could promote cell proliferation in HCC cell lines. In contrast, HDAC6 knockdown using small interfering RNA inhibited cell proliferation. At the molecular level, we demonstrated that HDAC6 could interact with p53 and attenuate its transcriptional activity through promotion of its degradation. Therefore, our results suggest a previously unknown HDAC6-p53 molecular network controlling HCC development.
