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Histone deacetylase 8 (HDAC8), a unique member of class I HDACs, shows remarkable correlation with advanced disease stage. The depletion of HDAC8 leads to inhibition of proliferation, apoptosis and cell cycle arrest in multiple malignant tumors. However, little is known about the contribution of HDAC8 to the tumorigenesis of gastric cancer (GC). The present study investigated expression of HDAC8 in GC cell lines and tissues, and the roles of HDAC8 inhibition in the proliferation, cell cycle and apoptosis of gastric cancer cells and explored the potential mechanisms. In the present study, quantitative real-time reverse transcription polymerase chain reaction (qRT-PCR), western blotting, and immunohistochemistry were used to examine the mRNA and protein expression of HDAC8 in GC cell lines and tissues. Then, the correlation between the clinicopathological parameters and the expression of HDAC8 was assessed. Finally, siRNA transfection and HDAC8 plasmid was performed to explore the functions of HDAC8 in GC progression in vitro. We found that the expression of HDAC8 was significantly upregulated both in GC cell lines and tumor tissues compared to human normal gastric epithelial cell, GES-1 and matched non-tumor tissues. Furthermore, depletion of HDAC8 remarkably inhibited GC cell proliferation, increased the apoptosis rate and G0/G1 phase percentage in vitro. Western blotting showed that the expression of protein promoting apoptosis such as, Bmf, activated caspase-3, caspase-6 were elevated following HDAC8 depletion. Our data exhibited an important role of HDAC8 in promoting gastric cancer tumorigenesis and identify this HDAC8 as a potential therapeutic target for the treatment of gastric cancer.

IntroductionRecently, increasing evidence has shown that long non-coding RNAs (lncRNAs) play critical roles in tumor progression and development. However, the expression pattern and biological function of lncRNA HULC (highly upregulated in liver cancer) in prostate cancer (PCa) remain largely unclear.Material and methodsThe expression of lncRNA HULC in 53 paired PCa tissues and cell lines was detected by quantitative real-time polymerase chain reaction (qRT-PCR). The χ2 test was used to explore the association of lncRNA HULC expression with clinicopathologic features. Kaplan-Meier analysis was used to detect the association between HULC expression and overall survival of PCa patients. Furthermore, the function of HULC in cell growth and metastasis was detected in PCa cells.ResultsOur data showed that HULC expression was upregulated in PCa tissues and cell lines compared to adjacent non-tumor tissues and the normal prostate cell line RWPE-1 (p < 0.05). High HULC expression was positively associated with advanced clinicopathologic features and poor overall survival (OS) for PCa patients (p < 0.05). HULC inhibition suppressed PCa cell growth and metastasis both in vitro and in vivo (p < 0.05). Furthermore, HULC knockdown reduced N-cadherin and vimentin expression and increased E-cadherin expression in PCa cells (p < 0.05).ConclusionsOur data suggested that lncRNA HULC might play oncogenic roles in PCa progression, which provided a novel therapeutic strategy for PCa patients.

Ferroptosis is a novel form of regulated cell death characterized by accumulated lipid reactive oxygen species (ROS) and inactivation of glutathione peroxidase 4 (GPX4). The present study aimed to investigate the role of microRNA (miRNA/miR)-15a in ferroptosis of prostate cancer cells. Bioinformatics analysis was performed to predict the potential interaction between miR-15a and the 3'-untranslated region (UTR) of GPX4 mRNA. The prostate cancer cell line, LNCAP was transfected with miR-15a mimics or small interfering (si)-GPX4. Reverse transcription-quantitative PCR and western blot analyses were performed to detect the mRNA and protein expression levels of GPX4, respectively. Biotin-RNA pull-down and dual-luciferase reporter assays were performed to verify the interaction between miR-15a and GPX4 mRNA. The Cell Counting Kit-8 assay was performed to assess cell proliferation, while lactate dehydrogenase (LDH) and intracellular ferrous iron levels were detected via ELISA. Lipid ROS and mitochondrial membrane potential (MMP) were assessed via flow cytometry and staining with C11-BIODIPY probes or JC-1. Furthermore, lipid peroxidation was identified by measuring malondialdehyde (MDA) levels. The results demonstrated that transfection with miR-15a mimics decreased GPX4 protein expression. Bioinformatics analysis revealed potential binding sites between miR-15a and the 3'-UTR region of GPX4, and RNA pull-down and the dual-luciferase reporter assays further confirmed the interaction between miR-15a and GPX4 mRNA. Both transfection with miR-15a mimics and si-GPX4 suppressed cell proliferation, elevated LDH release, accumulated intracellular ferrous iron and ROS, disrupted MMP and increased MDA levels. Taken together, the results of the present study suggest miR-15a induces ferroptosis by regulating GPX4 in prostate cancer cells, which provides evidence for investigating the therapeutic strategies of prostate cancer.

Our data suggest that miR-216b functions as a tumor suppressor in human GC by, at least partially, targeting HDAC8.

Prostate cancer (PCa) remains a leading cause of mortality among men in the United States and Western Europe. The molecular mechanism of PCa pathogenesis has not been fully elucidated. In the present study, the expression profile of E2F transcription factor 7 (E2F7) in PCa was examined using immunohistochemistry and reverse transcription-quantitative PCR, whilst cell cycle progression and apoptosis were determined using fluorescent cell activated sorting techniques. Cell viability was measured using Cell Counting Kit-8 in loss-and gain-of-function studies. Dual-luciferase reporter assay was used to verify if E2F7 was one of the potential targets of miR-30c. The staining score of E2F7 of PCa tissues was found to be notably higher compared with that of adjacent normal tissues. Suppression of E2F7 expression in PCa cell lines led to significantly reduced proliferation rates, increased proportion of cells in the G 1 phase of the cell cycle and higher apoptotic rates compared with those in negative control groups. Dual-luciferase reporter assay revealed E2F7 to be one of the binding targets of microRNA (miR)-30c. In addition, transfection of miR-30c mimics into PCa cells resulted in reduced cell viability, increased proportion of cells in the G 1 phase and higher apoptotic rates. By contrast, transfection with the miR-30c inhibitor led to lower apoptosis rates of PCa cells compared with negative control groups, whilst E2F7 siRNA co-transfection reversed stimulatory effects of miR-30c inhibitors on cell viability. In addition, the expression of cyclin-dependent kinase inhibitor p21 were found to be upregulated by transfection with either E2F7 siRNA or miR-30c mimics into PCa cells. In conclusion, the present study suggested that E2F7 may be positively associated with PCa cell proliferation by inhibiting p21, whereas E2F7 is in turn under regulation by miR-30c. These observations suggest the miR-30c/E2F7/p21 axis to be a viable therapeutic target for PCa.

The effect of chemotherapy of gastric cancer (GC) remains very poor because of multidrug resistance (MDR). However, the mechanisms underlying MDR of GC remains far from fully understood. The aim of this study is to illustrate the potential mechanisms of the MDR of GC at mainly the long non-coding RNA (lncRNA) level. In this study, GC cell line, SGC7901, and two MDR sublines, SGC7901/VCR and SGC7901/ADR were subjected to an lncRNA microarray analysis. Bioinformatics and verification experiments were performed to investigate the potential lncRNAs involved in the development of MDR. Pathway analysis indicated that 15 pathways corresponded to down-regulated transcripts and that 20 pathways corresponded to up-regulated transcripts (p-value cut-off is 0.05). GO analysis showed that the highest enriched GOs targeted by up-regulated transcripts were “system development” and the highest esenriched GOs targeted by the down-regulated transcripts were “sterol biosynthetic process”. Our study is the first to interrogate differentially expressed lncRNAs in human GC cell line and MDR sublines and indicates that lncRNAs are worthwhile for further study to be the novel candidate biomarkers for the clinical diagnosis of MDR and potential targets for further therapy.

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