Chao Ge

CD133 positive hepatocellular carcinoma cells possess high capacity for tumorigenicity.

Recently increasing reported data have suggested that only a small subset of cancer cells possess capability to initiate malignancies including leukemia and solid tumors, which was based on investigation in these cells displaying a distinct surface marker pattern within the primary cancers. CD133 is a putative hematopoietic and neuronal stem‐cell marker, which was also considered as a tumorigenic marker in brain and prostate cancer. We hypothesized that CD133 was a marker closely correlated with tumorigenicity, since it was reported that CD133 expressed in human fetal liver and repairing liver tissues, which tightly associated with hepatocarcinogenesis. Our findings showed that a small population of CD133 positive cells indeed exists in human hepatocellular carcinoma (HCC) cell lines and primary HCC tissues. From SMMC‐7721 cell line, CD133+ cells isolated by MACS manifested high tumorigenecity and clonogenicity as compared with CD133− HCC cells. The implication that CD133 might be one of the markers for HCC cancer stem‐like cells needed further investigation.

Cancer stem/progenitor cells are highly enriched in CD133+CD44+ population in hepatocellular carcinoma

Both our previous study and other reports have suggested that CD133, originally classified as a hematopoietic stem cell marker, could be used for enrichment of cancer stem cells (CSCs) in human hepatocellular carcinoma (HCC). It was also noted that not all of CD133+ cells were representative of CSCs. Further identification and characterization of CSCs or tumor‐initiating cells in HCC are necessary to better understand hepatocarcinogenesis. In present study, we demonstrated that CSC phenotype could be precisely defined by co‐expression of CD133 and CD44 cell surface markers. CD133+CD44+ HCC cells showed stem cell properties, including extensive proliferation, self‐renewal, and differentiation into the bulk of cancer cells. In vivo xenograft experiments revealed that, actually, the highly tumorigenic capacity of CD133+ cells as previously described was primarily attributed to CD133+CD44+ cell subpopulation, instead of their CD133+CD44− counterparts. Moreover, cells double‐positive for CD133 and CD44 exhibited preferential expression of some stem cell‐associated genes and were more resistant to chemotherapeutic agents due to the upregulation of ATP‐binding cassette (ABC) superfamily transporters, including ABCB1, ABCC1, and ABCG2, further supporting these cells as HCC cell origin. Our findings suggest that CD133+CD44+ cells might represent true cancer stem/progenitor cells in HCC, which could allow a better understanding of HCC initiation and progression, as well as establish a precise target for the development of more effective therapies.

Gain of miR-151 on chromosome 8q24.3 facilitates tumour cell migration and spreading through downregulating RhoGDIA

Recurrent chromosomal aberrations are often observed in hepatocellular carcinoma (HCC), but little is known about the functional non-coding sequences, particularly microRNAs (miRNAs), at the chromosomal breakpoints in HCC. Here we show that 22 miRNAs are often amplified or deleted in HCC. MicroRNA-151 (miR-151), a frequently amplified miRNA on 8q24.3, is correlated with intrahepatic metastasis of HCC. We further show that miR-151, which is often expressed together with its host gene FAK, encoding focal adhesion kinase, significantly increases HCC cell migration and invasion in vitro and in vivo, mainly through miR-151-5p, but not through miR-151-3p. Moreover, miR-151 exerts this function by directly targeting RhoGDIA, a putative metastasis suppressor in HCC, thus leading to the activation of Rac1, Cdc42 and Rho GTPases. In addition, miR-151 can function synergistically with FAK to enhance HCC cell motility and spreading. Thus, our findings indicate that chromosome gain of miR-151 is a crucial stimulus for tumour invasion and metastasis of HCC.

MicroRNA-30d promotes tumor invasion and metastasis by targeting Galphai2 in hepatocellular carcinoma†

The pathological relevance and significance of microRNAs (miRNAs) in hepatocarcinogenesis have attracted much attention in recent years; however, little is known about the underlying molecular mechanisms through which miRNAs are involved in the development and progression of hepatocellular carcinoma (HCC). In this study, we demonstrate that miR‐30d is frequently up‐regulated in HCC and that its expression is highly associated with the intrahepatic metastasis of HCC. Furthermore, the enhanced expression of miR‐30d could promote HCC cell migration and invasion in vitro and intrahepatic and distal pulmonary metastasis in vivo, while silencing its expression resulted in a reduced migration and invasion. Galphai2 (GNAI2) was identified as the direct and functional target of miR‐30d with integrated bioinformatics analysis and messenger RNA array assay. This regulation was further confirmed by luciferase reporter assays. In addition, our results, for the first time, showed that GNAI2 was frequently suppressed in HCC by way of quantitative reverse‐transcription polymerase chain reaction and immunohistochemical staining assays. The increase of the GNAI2 expression significantly inhibits, whereas knockdown of the GNAI2 expression remarkably enhances HCC cell migration and invasion, indicating that GNAI2 functions as a metastasis suppressor in HCC. The restoration of GNAI2 can inhibit miR‐30d–induced HCC cell invasion and metastasis. Conclusion: The newly identified miR‐30d/GNAI2 axis elucidates the molecular mechanism of HCC cell invasion and metastasis and represents a new potential therapeutic target for HCC treatment. (HEPATOLOGY 2010.)

Hypoxia-inducible MicroRNA-210 augments the metastatic potential of tumor cells by targeting vacuole membrane protein 1 in hepatocellular carcinoma†

As the “master” microRNA that is induced by hypoxia, miR‐210 is involved in multiple processes in the hypoxia pathway. However, whether miR‐210 mediates hypoxia‐induced tumor cell metastasis still remains unclear. Here, we demonstrate that miR‐210 is frequently up‐regulated in hepatocellular carcinoma (HCC) samples and promotes the migration and invasion of HCC cells. Furthermore, miR‐210 can be induced by hypoxia in HCC cells and mediates hypoxia‐induced HCC cell metastasis. We identify vacuole membrane protein 1 (VMP1) as the direct and functional downstream target of miR‐210; in addition, we show that its expression is negatively correlated with the expression of miR‐210 in HCC. Intriguingly, VMP1 is reduced by hypoxia, and down‐regulation of VMP1 by miR‐210 mediates hypoxia‐induced HCC cell metastasis. Conclusion: These findings extend our understanding of the function of miR‐210 in the hypoxia pathway, and this newly identified hypoxia/miR‐210/VMP1 pathway should facilitate the development of novel therapeutics against hypoxic tumor cells. (HEPATOLOGY 2011)

Hypoxia‐inducible factor 1 alpha–activated angiopoietin‐like protein 4 contributes to tumor metastasis via vascular cell adhesion molecule‐1/integrin β1 signaling in human hepatocellular carcinoma

Angiopoietin‐like protein 4 (ANGPTL4) plays complex and often contradictory roles in vascular biology and tumor metastasis, but little is known about its function in hepatocellular carcinoma (HCC) metastasis. In the present study, we showed that hypoxia‐inducible factor 1α (HIF‐1α) directly up‐regulates ANGPTL4, and its stableness positively correlates with ANGPTL4 expression in HCC tissue. Overexpression of ANGPTL4 significantly increased HCC cell transendothelial migration in vitro and intrahepatic and distal pulmonary metastasis in vivo, whereas silencing ANGPTL4 expression or treatment with a neutralizing antibody specific for ANGPTL4 protein resulted in a reduced transendothelial migration. We also found that serum ANGPTL4 is higher in HCC patients, compared to healthy control, and correlates with intrahepatic metastasis and histological grade. Further, secreted ANGPTL4 promotes transendothelial migration and metastasis of HCC cells in vitro and in vivo through the up‐regulation of vascular cell adhesion molecule‐1 (VCAM‐1) of human umbilical vein endothelial cells and the activation of the VCAM‐1/integrin β1 axis. Conclusion: ANGPTL4 is a target gene of HIF‐1α and acts as an important regulator in the metastasis of HCC. Serum ANGPTL4 correlates with tumor progression and metastasis and might be used to indicate prognosis in HCC patients. (HEPATOLOGY 2011 54:910–919;)

Genome‐wide screening reveals that miR‐195 targets the TNF‐α/NF‐κB pathway by down‐regulating IκB kinase alpha and TAB3 in hepatocellular carcinoma

Nuclear factor kappa B (NF‐κB) is an important factor linking inflammation and tumorigenesis. In this study we experimentally demonstrated through a high‐throughput luciferase reporter screen that NF‐κB signaling can be directly targeted by nearly 29 microRNAs (miRNAs). Many of these miRNAs can directly target NF‐κB signaling nodes by binding to their 3′ untranslated region (UTR). miR‐195, a member of the miR‐15 family, is frequently down‐regulated in gastrointestinal cancers, especially in hepatocellular carcinoma (HCC). The expression level of miR‐195 is inversely correlated with HCC tumor size. We further show that miR‐195 suppresses cancer cell proliferation and migration in vitro and reduces tumorigenicity and metastasis in vivo. Additionally, miR‐195 may exert its tumor suppressive function by decreasing the expression of multiple NF‐κB downstream effectors by way of the direct targeting of IKKα and TAB3. Conclusion: Multiple miRNAs are involved in the NF‐κB signaling pathway and miR‐195 plays important inhibitory roles in cancer progression and may be a potential therapeutic target. (Hepatology 2013;58:654–666)

Genome-wide copy number analyses identified novel cancer genes in hepatocellular carcinoma†‡

A powerful way to identify driver genes with causal roles in carcinogenesis is to detect genomic regions that undergo frequent alterations in cancers. Here we identified 1,241 regions of somatic copy number alterations in 58 paired hepatocellular carcinoma (HCC) tumors and adjacent nontumor tissues using genome‐wide single nucleotide polymorphism (SNP) 6.0 arrays. Subsequently, by integrating copy number profiles with gene expression signatures derived from the same HCC patients, we identified 362 differentially expressed genes within the aberrant regions. Among these, 20 candidate genes were chosen for further functional assessments. One novel tumor suppressor (tripartite motif‐containing 35 [TRIM35]) and two putative oncogenes (hairy/enhancer‐of‐split related with YRPW motif 1 [HEY1] and small nuclear ribonucleoprotein polypeptide E [SNRPE]) were discovered by various in vitro and in vivo tumorigenicity experiments. Importantly, it was demonstrated that decreases of TRIM35 expression are a frequent event in HCC and the expression level of TRIM35 was negatively correlated with tumor size, histological grade, and serum alpha‐fetoprotein concentration. Conclusion: These results showed that integration of genomic and transcriptional data offers powerful potential for identifying novel cancer genes in HCC pathogenesis. (HEPATOLOGY 2011;)

BMP4 Administration Induces Differentiation of CD133+ Hepatic Cancer Stem Cells, Blocking Their Contributions to Hepatocellular Carcinoma

CD133+ cancer stem cells (CSC) contribute to hepatocellular carcinoma (HCC) progression and resistance to therapy. Bone morphogenetic protein BMP4 plays an important role in hepatogenesis and hepatic stem cell differentiation, but little is known about its function in hepatic CSCs. In this study, we showed that high-dose exogenous BMP4 promotes CD133+ HCC CSC differentiation and inhibits the self-renewal, chemotherapeutic resistance, and tumorigenic capacity of these cells. Interestingly, we found that low-dose exogenous BMP4 upregulated CD133 protein expression in vitro, and endogenous BMP4 was preferentially expressed in CD133+ HCC CSCs, suggesting that low doses of BMP4 may facilitate CSC maintenance. A reduction in endogenous BMP4 levels decreased CD133 protein expression in vitro. In HCC tissues, expression of the BMP4 signaling target gene SMAD6 was positively correlated with CD133 expression. Activation of the Erk1/2 signaling pathway led to BMP4-mediated reduction in CD133 expression, which was reversed by treatment with MEK inhibitors. Taken together, our findings indicated that BMP4 might be a potent therapeutic agent in HCC that targets CSCs.

miRNA-200c inhibits invasion and metastasis of human non-small cell lung cancer by directly targeting ubiquitin specific peptidase 25

BackgroundGrowing evidence indicates that miR-200c is involved in carcinogenesis and tumor progression in non-small-cell lung cancer (NSCLC). However, its precise biological role remains largely elusive.MethodsThe functions of miR-200c and USP25 in migration/invasion and lung metastasis formation were determined by transwell and tail vein injection assays, respectively. The potential regulatory targets of miR-200c were determined by prediction tools, correlation with target protein expression, and luciferase reporter assay. The mRNA expression levels of miR-200c and USP25 were examined in NSCLC cell lines and patient specimens using quantitative reverse transcription-PCR. The protein expression levels of USP25 were examined in NSCLC cell lines and patient specimens using western blot and immunohistochemical staining.ResultsWe demonstrated that over-expression of miR-200c inhibited NSCLC cells migration, invasion, epithelial-mesenchymal transition (EMT) in vitro and lung metastasis formation in vivo. Further studies revealed that USP25 was a downstream target of miR-200c in NSCLC cells as miR-200c bound directly to the 3’-untranslated region of USP25, thus reducing both the messenger RNA and protein levels of USP25. Silencing of the USP25 gene recapitulated the effects of miR-200c over-expression. Clinical analysis indicated that miR-200c was negatively correlated with clinical stage, lymph node metastasis in NSCLC patients. Moreover, USP25 protein and mRNA level expressions were higher in NSCLC patients, compared to healthy control, and correlated with clinical stage and lymphatic node metastasis.ConclusionsThese findings indicate that miR-200c exerts tumor-suppressive effects for NSCLC through the suppression of USP25 expression and suggests a new therapeutic application of miR-200c in the treatment of NSCLC.