HULC is a long noncoding RNA overexpressed in hepatocellular carcinoma (HCC), but its functional contributions in this setting have not been determined. In this study, we explored the hypothesis that HULC contributes to malignant development by supporting abnormal lipid metabolism in hepatoma cells. HULC modulated the deregulation of lipid metabolism in HCC by activating the acyl-CoA synthetase subunit ACSL1. Immunohistochemical analysis of tissue microarrays revealed that approximately 77% (180/233) of HCC tissues were positive for ACSL1. Moreover, HULC mRNA levels correlated positively with ACSL1 levels in 60 HCC cases according to real-time PCR analysis. Mechanistic investigations showed that HULC upregulated the transcriptional factor PPARA, which activated the ACSL1 promoter in hepatoma cells. HULC also suppressed miR-9 targeting of PPARA mRNA by eliciting methylation of CpG islands in the miR-9 promoter. We documented the ability of HULC to promote lipogenesis, thereby stimulating accumulation of intracellular triglycerides and cholesterol in vitro and in vivo. Strikingly, ACSL1 overexpression that generates cholesterol was sufficient to enhance the proliferation of hepatoma cells. Further, cholesterol addition was sufficient to upregulate HULC expression through a positive feedback loop involving the retinoid receptor RXRA, which activated the HULC promoter. Overall, we concluded that HULC functions as an oncogene in hepatoma cells, acting mechanistically by deregulating lipid metabolism through a signaling pathway involving miR-9, PPARA, and ACSL1 that is reinforced by a feed-forward pathway involving cholesterol and RXRA to drive HULC signaling. Cancer Res; 75(5); 846-57. Ó2015 AACR.

Clock circadian regulator (CLOCK)/brain and muscle arnt-like protein-1 (BMAL1) complex governs the regulation of circadian rhythm through triggering periodic alterations of gene expression. However, the underlying mechanism of circadian clock disruption in hepatocellular carcinoma (HCC) remains unclear. Here, we report that a long noncoding RNA (lncRNA), highly upregulated in liver cancer (HULC), contributes to the perturbations in circadian rhythm of hepatoma cells. Our observations showed that HULC was able to heighten the expression levels of CLOCK and its downstream circadian oscillators, such as period circadian clock 1 and cryptochrome circadian clock 1, in hepatoma cells. Strikingly, HULC altered the expression pattern and prolonged the periodic expression of CLOCK in hepatoma cells. Mechanistically, the complementary base pairing between HULC and the 5' untranslated region of CLOCK mRNA underlay the HULC-modulated expression of CLOCK, and the mutants in the complementary region failed to achieve the event. Moreover, immunohistochemistry staining and quantitative real-time polymerase chain reaction validated that the levels of CLOCK were elevated in HCC tissues, and the expression levels of HULC were positively associated with those of CLOCK in clinical HCC samples. In functional experiments, our data exhibited that CLOCK was implicated in the HULC-accelerated proliferation of hepatoma cells in vitro and in vivo. Taken together, our data show that an lncRNA, HULC, is responsible for the perturbations in circadian rhythm through upregulating circadian oscillator CLOCK in hepatoma cells, resulting in the promotion of hepatocarcinogenesis. Thus, our finding provides new insights into the mechanism by which lncRNA accelerates hepatocarcinogenesis through disturbing circadian rhythm of HCC.

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Abstract.Intestinal trefoil factor (ITF, also named as trefoil factor 3, TFF3) is a member of the TFF-domain peptide family, which plays an essential role in the regulation of cell survival, cell migration and maintains mucosal epithelial integrity in the gastrointestinal tract. However, the underlying mechanisms and associated molecules remain unclear. The aim of this study was to explore the protective effects of ITF on gastric mucosal epithelium injury and its possible molecular mechanisms of action. In the present study, we show that ITF was able to promote the proliferation and migration of GES-1 cells via a mechanism that involves the PI3K/Akt signaling pathway. Western blot results indicated that ITF induced a dose-and time-dependent increase in the Akt signaling pathway. ITF also plays an essential role in the restitution of GES-1 cell damage induced by lipopolysaccharide (LPS). LPS induced the apoptosis of GES-1 cells, decreased cell viability significantly (P<0.01) and led to epithelial tight junction damage, which is attenuated via ITF treatment. The protective effect of ITF on the integrity of GES-1 was abrogated by inhibition of the PI3K/Akt pathway. Taken together, our results demonstrate that ITF promotes the proliferation and migration of gastric mucosal epithelial cells and preserves gastric mucosal epithelial integrity after damage is mediated by activation of the PI3K/Akt signaling pathway. This study suggested that the PI3K/Akt pathway could act as a key intracellular pathway in the gastric mucosal epithelium that may serve as a therapeutic target to preserve epithelial integrity during injury.