Meng Duan

Protein tyrosine phosphatase receptor S acts as a metastatic suppressor in hepatocellular carcinoma by control of epithermal growth factor receptor–induced epithelial-mesenchymal transition

Hepatocellular carcinoma (HCC) is the third‐most lethal cancer worldwide. Understanding the molecular pathogenesis of HCC recurrence and metastasis is the key to improve patients’ prognosis. In this study, we report that protein tyrosine phosphatase receptor S (PTPRS) is significantly down‐regulated in nearly 80% of HCCs, and its expression negatively correlates with aggressive pathological features, such as larger tumor size and advanced stage. In addition, PTPRS deficiency is independently associated with shorter survival and increased recurrence in patients, although 16.7% of HCCs show intratumor heterogeneous expression of PTPRS. Restoration of wild‐type, but not mutant, PTPRS expression significantly inhibits HCC cell migration and invasion in vitro as well as lung metastasis in vivo, whereas knockdown of its expression significantly promotes invasion and metastasis. Notably, PTPRS‐regulated HCC invasiveness is accompanied by typical changes of epithelial‐mesenchymal transition (EMT). Moreover, PTPRS forms a complex with epithermal growth factor receptor (EGFR) and regulates its tyrosine residues’ phosphorylation. Ectopic expression of EGFR reverses the metastasis‐inhibiting effects of PTPRS, whereas silencing of EGFR or inhibiting phosphorylation of key molecules in EGFR downstream pathways reinhibits EMT and metastasis caused by PTPRS down‐regulation. Meanwhile, promoter hypermethylation of PTPRS is frequently detected in HCC samples and cell lines. Treatment with a demethylation agent, 5‐aza‐2′‐deoxycytidine, recovers PTPRS expression in a dose‐dependent manner. Conclusions: Epigenetic inactivation of PTPRS may increase phosphorylation and activity of EGFR signaling to promote EMT and metastasis in HCC. (Hepatology 2015;62:1201‐1214)

Inferring the progression of multifocal liver cancer from spatial and temporal genomic heterogeneity.

Multifocal tumors developed either as independent tumors or as intrahepatic metastases, are very common in primary liver cancer. However, their molecular pathogenesis remains elusive. Herein, a patient with synchronous two hepatocellular carcinoma (HCC, designated as HCC-A and HCC-B) and one intrahepatic cholangiocarcinoma (ICC), as well as two postoperative recurrent tumors, was enrolled. Multiregional whole-exome sequencing was applied to these tumors to delineate the clonality and heterogeneity. The three primary tumors showed almost no overlaps in mutations and copy number variations. Within each tumor, multiregional sequencing data showed varied intratumoral heterogeneity (21.6% in HCC-A, 20.4% in HCC-B, 53.2% in ICC). The mutational profile of two recurrent tumors showed obvious similarity with HCC-A (86.7% and 86.6% respectively), rather than others, indicating that they originated from HCC-A. The evolutionary history of the two recurrent tumors indicated that intrahepatic micro-metastasis could be an early event during HCC progression. Notably, FAT4 was the only gene mutated in two primary HCCs and the recurrences. Mutation prevalence screen and functional experiments showed that FAT4, harboring somatic coding mutations in 26.7% of HCC, could potently inhibit growth and invasion of HCC cells. In HCC patients, both FAT4 expression and FAT4 mutational status significantly correlated with patient prognosis. Together, our findings suggest that spatial and temporal dissection of genomic alterations during the progression of multifocal liver cancer may help to elucidate the basis for its dismal prognosis. FAT4 acts as a putative tumor suppressor that is frequently inactivated in human HCC.

Mitogen-activated protein kinase kinase kinase 4 deficiency in intrahepatic cholangiocarcinoma leads to invasive growth and epithelial-mesenchymal transition

The molecular pathogenesis of intrahepatic cholangiocarcinoma (iCCA) is poorly understood, and its incidence continues to increase worldwide. Deficiency of mitogen‐activated protein kinase kinase kinase 4 (MAP3K4) has been reported to induce the epithelial‐mesenchymal transition (EMT) process of placental and embryonic development, yet its role in human cancer remains unknown. MAP3K4 has somatic mutation in iCCA so we sequenced all exons of MAP3K4 in 124 iCCA patients. We identified nine somatic mutations in 10 (8.06%) patients, especially in those with lymph node metastasis and intrahepatic metastasis. We also showed that messenger RNA and protein levels of MAP3K4 were significantly reduced in iCCA versus paired nontumor tissues. Furthermore, knockdown of MAP3K4 in cholangiocarcinoma cells markedly enhanced cell proliferation and invasiveness in vitro and tumor progression in vivo, accompanied by a typical EMT process. In contrast, overexpression of MAP3K4 in cholangiocarcinoma cells obviously reversed EMT and inhibited cell invasion. Mechanistically, MAP3K4 functioned as a negative regulator of EMT in iCCA by antagonizing the activity of the p38/nuclear factor κB/snail pathway. We found that the tumor‐inhibitory effect of MAP3K4 was abolished by inactivating mutations. Clinically, a tissue microarray study containing 322 iCCA samples from patients revealed that low MAP3K4 expression in iCCA positively correlated with aggressive tumor characteristics, such as vascular invasion and intrahepatic or lymph node metastases, and was independently associated with poor survival and increased recurrence after curative surgery. Conclusions: MAP3K4, significantly down‐regulated, frequently mutated, and potently regulating the EMT process in iCCA, was a putative tumor suppressor of iCCA. (Hepatology 2015;62:1804‐1816)

RANKL Promotes Migration and Invasion of Hepatocellular Carcinoma Cells via NF-κB-Mediated Epithelial-Mesenchymal Transition

Background Metastasis accounts for the most deaths in patients with hepatocellular carcinoma (HCC). Receptor activator of nuclear factor kappa B ligand (RANKL) is associated with cancer metastasis, while its role in HCC remains largely unknown. Methods Immunohistochemistry was performed to determine the expression of RANK in HCC tissue (n = 398). Quantitative real-time polymerase chain reaction (qRT-PCR) and Western blot were used to examine the expression of RANK, E-cadherin, N-cadherin, vimentin, Snail, Slug, Twist and MMPs in HCC cells. Wound healing and Transwell assays were used to evaluate cell migration and invasion ability. Results We found that expression of RANK, the receptor of RANKL, was significantly higher in HCC tumor tissues than in peritumor liver tissues (p<0.001). Constitutive expression of RANK was detected in HCC cell lines, which can be up-regulated when HCC cells were stimulated with RANKL. Notably, in vitro experiments showed that activation of RANKL-RANK axis significantly promoted migration and invasion ability of HCC cells. In addition, RANKL stimulation increased the expression levels of N-cadherin, Snail, and Twist, while decreased the expression of E-cadherin, with concomitant activation of NF-κB signaling pathway. Moreover, administration of the NF-κB inhibitor attenuated RANKL-induced migration, invasion and epithelial-mesenchymal transition of HCC cells. Conclusions RANKL could potentiate migration and invasion ability of RANK-positive HCC cells through NF-κB pathway-mediated epithelial-mesenchymal transition, which means that RANKL-RANK axis could be a potential target for HCC therapy.

Protein tyrosine phosphatase PTP4A1 promotes proliferation and epithelial-mesenchymal transition in intrahepatic cholangiocarcinoma via the PI3K/AKT pathway

The protein tyrosine phosphatase PTP4A1 is a key molecule that activates tyrosine phosphorylation, which is important for cancer progression and metastasis. However, the clinical implications and biological function of PTP4A1 in intrahepatic cholangiocarcinoma (ICC) remains unknown. Here, we showed that PTP4A1 was frequently overexpressed in ICC versus adjacent non-tumor tissues. This overexpression significantly correlated with aggressive tumor characteristics like the presence of lymph node metastasis and advanced tumor stages. Survival analysis further indicated that high PTP4A1 expression was significantly and independently associated with worse survival and increased recurrence in ICC patients. Moreover, through forced overexpression and knock-down of PTPT4A1, we demonstrated that PTP4A1 could significantly promote ICC cells proliferation, colony formation, migration, and invasion in vitro, and markedly enhance tumor progression in vivo. Mechanistically, PTP4A1 was involved in PI3K/AKT signaling and its downstream molecules, such as phosphorylation level of GSK3β and up-regulation of CyclinD1, in ICC cells to promote proliferation. Importantly, PTP4A1 induced ICC cells invasion was through activating PI3K/AKT signaling controlled epithelial-mesenchymal transition (EMT) process by up-regulating Zeb1 and Snail. Thus, PTP4A1 may serve as a potential oncogene that was a valuable prognostic biomarker and therapeutic target for ICC.

Diverse modes of clonal evolution in HBV-related hepatocellular carcinoma revealed by single-cell genome sequencing

Hepatocellular carcinoma (HCC) is a cancer of substantial morphologic, genetic and phenotypic diversity. Yet we do not understand the relationship between intratumor heterogeneity and the associated morphologic/histological characteristics of the tumor. Using single-cell whole-genome sequencing to profile 96 tumor cells (30-36 each) and 15 normal liver cells (5 each), collected from three male patients with HBV-associated HCC, we confirmed that copy number variations occur early in hepatocarcinogenesis but thereafter remain relatively stable throughout tumor progression. Importantly, we showed that specific HCCs can be of monoclonal or polyclonal origins. Tumors with confluent multinodular morphology are the typical polyclonal tumors and display the highest intratumor heterogeneity. In addition to mutational and copy number profiles, we dissected the clonal origins of HCC using HBV-derived foreign genomic markers. In monoclonal HCC, all the tumor single cells exhibit the same HBV integrations, indicating that HBV integration is an early driver event and remains extremely stable during tumor progression. In addition, our results indicated that both models of metastasis, late dissemination and early seeding, have a role in HCC progression. Notably, early intrahepatic spreading of the initiating clone leads to the formation of synchronous multifocal tumors. Meanwhile, we identified a potential driver gene ZNF717 in HCC, which exhibits a high frequency of mutation at both single-cell and population levels, as a tumor suppressor acting through regulating the IL-6/STAT3 pathway. These findings highlight multiple distinct tumor evolutionary mechanisms in HCC, which suggests the need for specific treatment strategies.

Telomere length variation in tumor cells and cancer‐associated fibroblasts: potential biomarker for hepatocellular carcinoma

The role of telomere dysfunction and aberrant telomerase activities in hepatocellular carcinoma (HCC) has been overlooked for many years. This study aimed to delineate the variation and prognostic value of telomere length in HCC. Telomere‐specific fluorescence in situ hybridization (FISH) and qPCR were used to evaluate telomere length in HCC cell lines, tumor tissues, and isolated non‐tumor cells within the tumor. Significant telomere attrition was found in tumor cells and cancer‐associated fibroblasts (CAFs) compared to their normal counterparts, but not in intratumor leukocytes or bile duct epithelial cells. Clinical relevance and prognostic value of telomere length were investigated on tissue microarrays of 257 surgically treated HCC patients. Reduced intensity of telomere signals in tumor cells or CAFs correlated with larger tumor size and the presence of vascular invasion (p < 0.05). Shortened telomeres in tumor cells or CAFs associated with reduced survival and increased recurrence, and were identified as independent prognosticators for HCC patients (p < 0.05). These findings were validated in an independent HCC cohort of 371 HCC patients from The Cancer Genome Atlas (TCGA) database, confirming telomere attrition and its prognostic value in HCC. We also showed that telomerase reverse transcriptase promoter (TERTp) mutation correlated with telomere shortening in HCC. Telomere variation in tumor cells and non‐tumor cells within the tumor microenvironment of HCC was a valuable prognostic biomarker for this fatal malignancy.

FOXP3 Is a HCC suppressor gene and Acts through regulating the TGF-β/Smad2/3 signaling pathway

BackgroundFOXP3 has been discovered to be expressed in tumor cells and participate in the regulation of tumor behavior. Herein, we investigated the clinical relevance and biological significance of FOXP3 expression in human hepatocellular carcinoma (HCC).MethodsExpression profile of FOXP3 was analyzed using real-time RT-PCR, western blotting and immunofluorescence on HCC cell lines, and immunostaing of a tissue microarray containing of 240 primary HCC samples. The potential regulatory roles of FOXP3 were dissected by an integrated approach, combining biochemical assays, analysis of patient survival, genetic manipulation of HCC cell lines, mouse xenograft tumor models and chromatin immunoprecipitation (ChIP) sequencing.ResultsFOXP3 was constitutively expressed in HCC cells with the existence of splice variants (especially exon 3 and 4 deleted, Δ3,4-FOXP3). High expression of FOXP3 significantly correlated with low serum α-fetoprotein (AFP) level, absence of vascular invasion and early TNM stage. Survival analyses revealed that increased FOXP3 expression was significantly associated with better survival and reduced recurrence, and served as an independent prognosticator for HCC patients. Furthermore, FOXP3 could potently suppress the proliferation and invasion of HCC cells in vitro and reduce tumor growth in vivo. However, Δ3,4-FOXP3 showed a significant reduction in the tumor-inhibiting effect. The inhibition of FOXP3 on HCC aggressiveness was acted probably by enhancing the TGF-β/Smad2/3 signaling pathway.ConclusionOur findings suggest that FOXP3 suppresses tumor progression in HCC via TGF-β/Smad2/3 signaling pathway, highlighting the role of FOXP3 as a prognostic factor and novel target for an optimal therapy against this fatal malignancy.

Naive Treg-like CCR7(+) mononuclear cells indicate unfavorable prognosis in hepatocellular carcinoma.

Chemokine receptor-like 1 (CCRL1) has the potential in creating a low level of CCL19 and CCL21 to hinder CCR7+ cell tracking to tumor tissue. Previously, we found a tumor suppressive role of CCRL1 by impairing CCR7-related chemotaxis of tumor cells in human hepatocellular carcinoma (HCC). Here, we reported a contribution of CCR7+ mononuclear cells in the tumor microenvironment to the progression of disease. Immunohistochemistry was used to investigate the distribution and clinical significance of CCR7+ cells in a cohort of 240 HCC patients. Furthermore, the phenotype, composition, and functional status of CCR7+ cells were determined by flow cytometry, immunofluorescence, and in vitro co-culture assays. We found that CCR7+ mononuclear cells were dispersed around tumor tissue and negatively related to tumoral expression of CCRL1 (P < 0.001, r = 0.391). High density of CCR7+ mononuclear cells positively correlated with the absence of tumor capsule, vascular invasion, and poor differentiation (P < 0.05). Survival analyses revealed that increased number of CCR7+ mononuclear cells was significantly associated with worse survival and increased recurrence. We found that CCR7+ mononuclear cells featured a naive Treg-like phenotype (CD45RA+CD25+FOXP3+) and possessed tumor-promoting potential by producing TGF-β1. Moreover, CCR7+ cells were also composed of several immunocytes, a third of which were CD8+ T cells. CCR7+ Treg-like cells facilitate tumor growth and indicate unfavorable prognosis in HCC patients, but fortunately, their tracking to tumor tissue is under the control of CCRL1.