Amplification of 1q is one of the most frequent chromosomal alterations in human hepatocellular carcinoma (HCC). In this study we identified and characterized a novel oncogene, Maelstrom (MAEL), at 1q24. Amplification and overexpression of MAEL was frequently detected in HCCs and significantly associated with HCC recurrence (P 5 0.031) and poor outcome (P 5 0.001). Functional study demonstrated that MAEL promoted cell growth, cell migration, and tumor formation in nude mice, all of which were effectively inhibited when MAEL was silenced with short hairpin RNA (shRNAs). Further study found that MAEL enhanced AKT activity with subsequent GSK-3b phosphorylation and Snail stabilization, finally inducing epithelial-mesenchymal transition (EMT) and promoting tumor invasion and metastasis. In addition, MAEL up-regulated various stemness-related genes, multidrug resistance genes, and cancer stem cell (CSC) surface markers at the messenger RNA (mRNA) level. Functional study demonstrated that overexpression of MAEL increased self-renewal, chemoresistance, and tumor metastasis. Conclusion: MAEL is an oncogene that plays an important role in the development and progression of HCC by inducing EMT and enhancing the stemness of HCC. (HEPA-TOLOGY 2014;59:531-543) H epatocellular carcinoma (HCC) is the fifth most common cancer and ranks as the third leading cause of cancer-related deaths in the world. 1 It is believed that HCC pathogenesis is a longterm progressive process involving the accumulation of multiple genetic and epigenetic alterations. 2 Amplification of the long arm of chromosome 1 has been detected in 58%-78% of primary HCC cases, suggesting that one or more oncogenes within the amplified region play a critical role in HCC development. 3,4 Our previous work had demonstrated that CHD1L at 1q21 plays a critical oncogenic role in the development and progression of HCC. Overexpression of CHD1L promotes cell proliferation, 5 induces tumor metastasis by way of epithelial-to-mesenchymal transition (EMT), 6 sustains cell survival, and increases drug resistance by inhibiting Nur77-mediated apoptosis. 7 Recently, we performed an integrative RNA sequencing (RNA-Seq) to identify differentially expressed genes between three pairs of clinical samples of HCC and their adjacent nontumor tissues. 8 Overexpression of Maelstrom (MAEL) at 1q24 was observed in all three HCC tumor tissues compared with their matched nontumor counterparts.The MAEL gene was initially identified in Drosophila 9 and is required for spermatogenesis and meiosis. 10 The human MAEL protein contains a high mobility group (HMG) domain in its N-terminal segment that is known to mediate DNA binding and a novel MAEL-specific domain in the C-terminal segment. 11

Background and Aims: Cancer cells prefer aerobic glycolysis to maintain growth advantages, but the role of long non-coding RNAs (lncRNAs) in glycometabolism still remains unclear. Here we identified one cytoplasmic lncRNA LINC01554 as a significantly downregulated lncRNA in hepatocellular carcinoma (HCC) and aimed to investigate its role in cellular glucose metabolism in the development and progression of HCC. Methods: Quantitative real-time PCR was used to determine the expression level of LINC01554. Downregulation of LINC01554 by miR-365a at transcriptional level was assessed by luciferase reporter assay. Subcellular fractionation assay and RNA fluorescence in situ hybridization were performed to detect the subcellular localization of LINC01554. RNA pull-down assay, mass spectrometry, and RNA immunoprecipitation assay were used to identify the underlying molecular mechanisms. The tumor-suppressive function of LINC01554 was determined by both in vitro assay and nude mice xenograft model. Results: LINC01554 was frequently downregulated in HCC, which was significantly associated with tumor invasion ( P = 0.005), tumor size ( P = 0.041), tumor staging ( P = 0.023) and shorter survival ( P = 0.035) of HCC patients. Luciferase reporter assay unraveled that LINC01554 was negatively regulated by miR-365a. Subcellular fractionation assay and RNA FISH revealed the cytoplasmic predominance of LINC01554 in MIHA cells and HCC clinical samples. Ectopic expression of LINC01554 inhibited HCC cell growth, colony formation in soft agar, foci formation, and tumor formation in nude mice. LINC01554 promoted the ubiquitin-mediated degradation of PKM2 and inhibited Akt/mTOR signaling pathway to abolish aerobic glycolysis in HCC cells. Further study found that LINC01554-knockout could effectively reverse the tumor-suppressive effect of LINC01554. Conclusions: Our results identify LINC01554 as a novel tumor suppressor in HCC and unravel its underlying molecular mechanism in reprogramming cellular glucose metabolism. LINC01554 could possibly serve as a novel prognostic biomarker and provide the rationale for HCC therapy.

MicroRNAs (miRNAs) play a critical role in development and progression of cancers. Deregulation of MicroRNA-9 (miR-9) has been documented in many types of cancers but their role in the development of esophageal squamous cell carcinoma (ESCC) has not been studied. This study aimed to investigate the effect of miR-9 in esophageal cancer metastasis. The up-regulation of miR-9 was frequently detected in primary ESCC tumor tissue, which was significantly associated with clinical progression (P = 0.022), lymph node metastasis (P = 0.007) and poor overall survival (P < 0.001). Functional study demonstrated that miR-9 promoted cell migration and tumor metastasis, which were effectively inhibited when expression of miR-9 was silenced. Moreover, we demonstrated that miR-9 interacted with the 3′-untranslated region of E-cadherin and down-regulated its expression, which induced β-catenin nuclear translocation and subsequently up-regulated c-myc and CD44 expression. In addition, miR-9 induced epithelial-mesenchymal transition (EMT) in ESCC, a key event in tumor metastasis. Taken together, our study demonstrates that miR-9 plays an important role in ESCC metastasis by activating β-catenin pathway and inducing EMT via targeting E-cadherin. Our study also suggests miR-9 can be served as a new independent prognostic marker and/or as a novel potential therapeutic target for ESCC.

The hepatitis B virus (HBV) X protein (HBx) has a key role in the molecular pathogenesis of HBV-related hepatocellular carcinoma (HCC). However, the mechanism of HBx-mediated hepatocarcinogenesis remains to be elucidated. In this study, we aimed to better understand the effects of HBx on gene-expression profiles that participate in hepatocarcinogenesis and the mechanism by which HBx regulates these genes. Differentially expressed genes between L02-HBx and L02-Vector control cells were identified by microarray and validated using quantitative real-time PCR. HBx upregulates 456 genes and downregulates 843 genes, including programmed cell death 4 (PDCD4). PDCD4 was downregulated in clinical HCC specimens and the downregulation of PDCD4 in HCC is correlated with HBx. Furthermore, overexpression experiments in HCC cells proved that PDCD4 has strong tumor-suppressive effects both in vitro and in vivo, and may induce cell apoptosis to suppress the development of HCC. HBx induces expression of DNA methyltransferases (DNMTs), but failed to change the methylation status of the PDCD4 promoter. HBx downregulates PDCD4 expression at least partially through miR-21. Taken together, this study reported for the first time that HBx downregulates PDCD4 and upregulates miR-21 expression. The overexpression of PDCD4 could suppress tumorigenicity. The deregulation of PDCD4 by HBx through miR-21 represents a potential novel mechanism of the downregulation of PDCD4 in HBV-related HCC and provides new insights into HCC development.

Loss of chromosome 19p is one of the most frequent allelic imbalances in esophageal squamous cell carcinoma (ESCC), suggesting the existence of one or more tumor suppressor genes within this region. In this study, we investigated a role in ESCCs for a candidate tumor suppressor gene located at 19p13.3, the Ras-like small GTPase DIRAS1. Downregulation of DIRAS1 occurred in approximately 50% of primary ESCCs where it was associated significantly with advanced clinical stage, lymph node metastasis, and poor overall survival. LOH and promoter methylation analyses suggested that loss of DIRAS1 expression was mediated by epigenetic mechanisms. Functional studies established that ectopic re-expression of DIRAS1 in ESCC cells inhibited cell proliferation, clonogenicity, cell motility, and tumor formation. Mechanistic investigations suggested that DIRAS1 acted through extracellular signal-regulated kinase (ERK1/2; MAPK3/1) and p38 mitogen-activated protein kinase (MAPK; MAPK14) signaling to trigger BAD Ser112 dephosphorylation and matrix metalloproteinase (MMP)2/9 transcriptional inactivation to promote apoptosis and inhibit metastasis, respectively. Taken together, our results revealed that DIRAS1 has a pivotal function in ESCC pathogenesis, with possible use as a biomarker and intervention point for new therapeutic strategies. Cancer Res; 73(7); 2298-309. Ó2013 AACR.

Mesenchymal stem cells (MSCs) were adenovirally engineered to secrete interleukin-12 (AdIL-12-MSCs) and evaluated for their anticarcinogenesis efficacy against three kinds of unestablished tumor models including B16 melanoma, LLC Lewis lung cancer and HCC hepatoma. Injection of AdIL-12-MSCs into protected mice before tumor inoculation prevented all of 12 mice in B16 preventive groups, 10 out of 12 in LLC lung cancer model and 11 out of 12 mice in HCC hepatoma model from developing tumors, whereas the control groups pre-receiving PBS were validated for 100% carcinogenesis; the tumor formation rates in free-AdIL-12 and vacant MSC groups were unveiled between approximately 83 and 100% even with plentiful angiogenesis and newborn lymphatic vessels, as well as distant metastases. As a novel approach, AdIL-12-MSC has revealed expected preventive effects on carcinogenesis (P<0.01) with low-toxic, broad-spectrum and long-range superiorities. In conclusion, our data indicate that AdIL-12-MSC possess the potential for tropism to preclinical tumor lesions and deprives surviving or hibernating tumor cells, which have escaped from conventional treatments, of revival and recurrence.

No abstract

No abstract