Involvement of PI3K/PTEN/AKT/mTOR pathway in invasion and metastasis in hepatocellular carcinoma: Association with MMP-9

Recent advances in cytogenetics and molecular biology of adult hepatocellular tumors: implications for imaging and management

Focal nodular hyperplasia (FNH), hepatocellular adenoma (HCA), and hepatocellular carcinoma (HCC) compose hepatocellular neoplasms that occur in adults. These tumors demonstrate characteristic epidemiologic and histopathologic features and clinical and imaging manifestations. HCAs are monoclonal neoplasms characterized by increased predilection to hemorrhage or rupture and occasional transformation to HCC. On the other hand, FNH is a polyclonal tumorlike lesion that occurs in response to increased perfusion and has an indolent clinical course. Up to 90% of HCCs occur in the setting of cirrhosis. Chronic viral hepatitis (hepatitis B and hepatitis C) infection and metabolic syndrome are major risk factors that can induce HCCs in nonfibrotic liver. Recent advances in pathology and genetics have led to better understanding of the histogenesis, natural history, and molecular events that determine specific oncologic pathways used by these neoplasms. HCAs are now believed to result from specific genetic mutations involving TCF1 (transcription factor 1 gene), IL6ST (interleukin 6 signal transducer gene), and CTNNB1 (β catenin-1 gene); FNHs are characterized by an "imbalance" of angiopoietin. While the β catenin signaling pathway is associated with well- and moderately differentiated HCCs, mutations involving p53 (tumor protein 53 gene), MMP14 (matrix metalloproteinase 14 gene), and RhoC (Ras homolog gene family, member C) are associated with larger tumor size, higher tumor grade with resultant shortened tumor-free survival, and poor prognosis. Fibrolamellar carcinoma (FLC), a unique HCC subtype, exhibits genomic homogeneity that partly explains its better overall prognosis. On the basis of recent study results involving cytogenetics and oncologic pathways of HCCs, novel drugs that act against molecular targets are being developed. Indeed, sorafenib (a multikinase inhibitor) is currently being used in the successful treatment of patients with advanced HCC. Characterization of genetic abnormalities and genotype-phenotype correlations in adult hepatocellular tumors provides better understanding of tumor pathology and biology, imaging findings, prognosis, and response to molecular therapeutics.

PI3Kα inhibitors that inhibit metastasis

Previous genetic analyses have suggested that mutations of the genes encoding PI3Kα facilitate invasion and metastasis but have less effect on primary tumor growth. These findings have major implications for therapeutics but have not been factored into pre-clinical drug development designs. Here we show that the inhibition of PI3Kα by newly designed small molecule inhibitors prevented metastasis formation in mice but had much less effect on the growth of subcutaneous xenografts or primary intra-abdominal tumors. These data support the idea that PI3Kα plays an important role in the metastatic process and suggest a more informed strategy for selecting drugs worthy of further development for clinical application.

Loss of phosphatase and tensin homolog enhances cell invasion and migration through AKT/Sp-1 transcription factor/matrix metalloproteinase 2 activation in hepatocellular carcinoma and has clinicopathologic significance

Phosphatase and tensin homolog (PTEN) is frequently inactivated in cancers and is associated with advanced stages of cancers or metastasis. However, the molecular mechanism of PTEN in hepatocellular carcinoma (HCC) metastasis is unclear. In this study, we found frequent (47.5%, n = 40) protein underexpression of PTEN in human HCCs compared with their corresponding nontumorous livers. Significantly, PTEN underexpression was associated with larger tumor size (P = 0.021), tumor microsatellite formation (P = 0.027), and shorter overall survival of patients (P = 0.035). Using different cell models, we observed that PTEN-knockdown HCC cells and PTEN-knockout mouse embryonic fibroblasts (MEFs) had enhanced cell migratory and invasive abilities. In addition to activation of AKT, there was up-regulation of the Sp1 transcription factor (SP1) and matrix metalloproteinase 2 (MMP2), as well as MMP2 activation in PTEN-knockdown HCC cells and PTEN(-/-) MEFs. With dual luciferase reporter assay, exogenous expression of SP1 in HCC cells led to enhanced MMP2 promoter activity by up to 74%, whereas deletion of the putative SP1 binding site on the MMP2 promoter led to reduced promoter activity by up to 65%. Using chromatin immunoprecipitation assay, we documented increased binding of SP1 to the MMP2 promoter in PTEN-knockdown HCC cells. Overexpression of SP1 and MMP2 was significantly but negatively associated with PTEN underexpression in human HCCs.

CONCLUSION

Our results show that PTEN was underexpressed in HCCs, and this underexpression was associated with more aggressive biological behavior and poorer patient survival. We have provided the first evidence that MMP2 up-regulation upon PTEN loss is SP1-dependent. Our findings indicate that PTEN plays a significant role in down-regulating HCC cell invasion via the AKT/SP1/MMP2 pathway.

Insulin resistance and other metabolic risk factors in the pathogenesis of hepatocellular carcinoma

Coinciding with the increased incidence of hepatocellular carcinoma (HCC), there has been a significant increase in the global incidence of obesity and diabetes mellitus (DM), the two major risk factors for nonalcoholic steatohepatitis (NASH). There are many causes of HCC, and nonalcoholic fatty liver disease/NASH is now emerging as a leading risk factor owing to the epidemic of obesity and type 2 DM. The mechanisms leading to HCC in obesity and type 2 DM likely involve interactions between several signaling pathways, including oxidative stress, inflammation, oncogenes, adiponectins, and insulin resistance associated with visceral adiposity and diabetes.

Des-γ-carboxyl prothrombin induces matrix metalloproteinase activity in hepatocellular carcinoma cells by involving the ERK1/2 MAPK signalling pathway

Des-γ-carboxy prothrombin (DCP), an aberrant prothrombin produced by hepatocellular carcinoma (HCC) cells, has been shown to be associated with the biological malignant potential of HCC. The aim of this study was to evaluate the effect of DCP on HCC cell growth and metastasis, and to explore the underlying molecular mechanisms. DCP significantly stimulated HCC cell growth, as measured by cell counting kit-8 assay. Transwell chamber assay showed that DCP increased HCC cell migration through reconstituted extracellular matrix (Matrigel). Gelatin zymography assay and Western blot analysis demonstrated that DCP increased the secretion and expression of matrix metalloproteinase (MMP)-2 and MMP-9 in the supernatant of cultured HCC cells and on tumour cell membranes. DCP was found to bind to the cell surface receptor Met, resulting in Met phosphorylation and subsequent activation of the epidermal growth factor receptor (EGFR). Western blot analysis demonstrated that DCP stimulated a sequential kinase phosphorylation cascade including ERK1/2, MEK1/2 and c-Raf, indicating activation of the extracellular signal-regulated kinase/mitogen activated protein kinase (ERK1/2 MAPK) signalling pathway. Furthermore, blocking ERK1/2 MAPK activation with ERK1/2 inhibitor PD98059 essentially abolished the DCP-induced MMP-2 and MMP-9 activity, confirming the signalling pathway of DCP stimulation. Taken together, these results suggested that DCP stimulates HCC growth and promotes HCC metastasis by increasing the activity of MMP-2 and MMP-9 through activation of the ERK1/2 MAPK signalling pathway.

Angiotensin type I receptor blockade in conjunction with enhanced Akt activation restores coronary collateral growth in the metabolic syndrome

We have previously demonstrated that Akt was required for repetitive ischemia (RI)-induced coronary collateral growth (CCG) in healthy rats but was not activated by RI in the metabolic syndrome (JCR:LA-cp rats) where CCG was impaired. Here we hypothesized that failure of angiotensin type I receptor (AT₁R) blockers to restore Akt activation is a key determinant of their inability to completely restore CCG in the metabolic syndrome. Therefore, we investigated whether adenovirus-mediated delivery of constitutively active Akt (MyrAkt-Adv) in conjunction with AT₁R blockade (candesartan) was able to restore RI-induced CCG in JCR:LA-cp rats. Successful myocardial MyrAkt-Adv delivery was confirmed by a >80% transduction efficiency and an approximately fourfold increase in Akt expression and activation. CCG was assessed by myocardial blood flow measurements in the normal and collateral-dependent zones. MyrAkt-Adv alone significantly increased RI-induced CCG in JCR:LA-cp rats (~30%), but it completely restored CCG in conjunction with administration of candesartan. In contrast, dominant negative Akt (DN-Akt-Adv) reversed the beneficial effect of candesartan on CCG in JCR:LA-cp rats. We conclude that optimal restoration of coronary collateral growth in JCR:LA-cp rats requires a combination of AT₁R blockade with constitutive Akt activation. These findings may carry implications for metabolic syndrome patients in need of coronary revascularization.

Mammalian target of rapamycin regulates expression of β-catenin in hepatocellular carcinoma

Although evidence has shown that both the mammalian target of rapamycin and β-catenin are involved in hepatocellular carcinoma, little is known about their relationship in pathogenesis of hepatocellular carcinoma. To investigate the expression of phosphorylated mammalian target of rapamycin and β-catenin and their prognostic impacts, as well as their relationship in hepatocellular carcinoma, we analyzed 63 human hepatocellular carcinoma samples by immunohistochemistry. Phosphorylated mammalian target of rapamycin cytoplasmic and β-catenin cytoplasmic/nuclear-positive immunoreactivities were observed in 63.5% (40/63) and 55.6% (35/63) of the hepatocellular carcinoma specimens, respectively. Significant associations were found between cytoplasmic β-catenin and phosphorylated mammalian target of rapamycin expression and tumor size (both P < .01) and metastasis (P < .01 and P < .05, respectively). In addition, β-catenin expression in the cytoplasm was closely associated with the expression of phosphorylated mammalian target of rapamycin. To further explore the relationship between mammalian target of rapamycin and β-catenin, hepatocellular carcinoma HepG2 and Hep3B cells were treated with β-catenin siRNA and mammalian target of rapamycin inhibitor, rapamycin; and the expression of phosphorylated mammalian target of rapamycin and β-catenin in cells was then measured by Western blot. The activity of Wnt/β-catenin signaling pathway was also assessed by luciferase reporter assay. The cell viability and proliferation were evaluated by thiazolyl blue tetrazolium bromide assay and [(3)H]-thymidine incorporation assay. The results showed that the level of β-catenin protein expression was markedly decreased by rapamycin in HepG2 and Hep3B cells. The reduction of β-catenin and mammalian target of rapamycin resulted in inhibition of cell viability proliferation, but the combination of reduction of β-catenin and mammalian target of rapamycin did not show a synergistic effect on the inhibition of cell viability and proliferation in HepG2 and Hep3B cells. In conclusion, the present study showed that, for the first time, mammalian target of rapamycin regulated the expression level of β-catenin in hepatocellular carcinoma. Both mammalian target of rapamycin and β-catenin play important roles in the growth, metastasis, and prognosis of hepatocellular carcinoma.

Phytochemicals: cancer chemoprevention and suppression of tumor onset and metastasis

Carcinogenesis is a multi-step process which could be prevented by phytochemicals. Phytochemicals from dietary plants and other plant sources such as herbs are becoming increasingly important sources of anticancer drugs or compounds for cancer chemoprevention or adjuvant chemotherapy. Phytochemicals can prevent cancer initiation, promotion, and progression by exerting anti-inflammatory and anti-oxidative stress effects which are mediated by integrated Nrf2, NF-kappaB, and AP-1 signaling pathways. In addition, phytochemicals from herbal medicinal plants and/or some dietary plants developed in recent years have been shown to induce apoptosis in cancer cells and inhibition of tumor growth in vivo. In advanced tumors, a series of changes involving critical signaling molecules that would drive tumor cells undergoing epithelial-mesenchymal transition and becoming invasive. In this review, we will discuss the potential molecular targets and signaling pathways that mediate tumor onset and metastasis. In addition, we will shed light on some of the phytochemicals that are capable of targeting these signaling pathways which would make them potentially applicable to cancer chemoprevention, treatment and control of cancer progression.

Sirolimus plus sorafenib in treating HCC recurrence after liver transplantation: A case report

A case of hepatocellular carcinoma (HCC) with pulmonary recurrence after liver transplantation for HCC is presented in this report. The patient showed disease progression on sorafenib therapy demonstrated by computed tomography scans as well as serial serum α-fetoprotein (AFP) elevation. After his immunosuppression therapy was successfully transitioned to sirolimus and a continuation of sorafenib, he achieved partial remission based on RECIST criteria and normalization of AFP. Mammalian target of rapamycin inhibitors including sirolimus alone or in conjunction with sorafenib may be useful in the treatment of post transplant HCC.

The tumor microenvironment in hepatocellular carcinoma: current status and therapeutic targets

A growing body of literature highlights the cross-talk between tumor cells and the surrounding peri-tumoral stroma as a key modulator of the processes of hepatocarcinogenesis, epithelial mesenchymal transition (EMT), tumor invasion and metastasis. The tumor microenvironment can be broadly classified into cellular and non-cellular components. The major cellular components include hepatic stellate cells, fibroblasts, immune, and endothelial cells. These cell types produce the non-cellular components of the tumor stroma, including extracellular matrix (ECM) proteins, proteolytic enzymes, growth factors and inflammatory cytokines. The non-cellular component of the tumor stroma modulates hepatocellular carcinoma (HCC) biology by effects on cancer signaling pathways in tumor cells and on tumor invasion and metastasis. Global gene expression profiling of HCC has revealed that the tumor microenvironment is an important component in the biologic and prognostic classification of HCC. There are substantial efforts underway to develop novel drugs targeting tumor-stromal interactions. In this review, we discuss the current knowledge about the role of the tumor microenvironment in pathogenesis of HCC, the role of the tumor microenvironment in the classification of HCC and efforts to develop treatments targeting the tumor microenvironment.

Transcriptional and post-transcriptional control of DNA methyltransferase 3B is regulated by phosphatidylinositol 3 kinase/Akt pathway in human hepatocellular carcinoma cell lines

DNA methyltransferases (DNMTs) are essential for maintenance of aberrant methylation in cancer cells and play important roles in the development of cancers. Unregulated activation of PI3K/Akt pathway is a prominent feature of many human cancers including human hepatocellular carcinoma (HCC). In present study, we found that DNMT3B mRNA and protein levels were decreased in a dose- and time-dependent manner in HCC cell lines with LY294002 treatment. However, we detected that LY294002 treatment did not induce increase of the degradation of DNMT3B protein using protein decay assay. Moreover we found that Akt induced alteration of the expression of DNMT3B in cells transfected with myristylated variants of Akt2 or cells transfected with small interfering RNA respectively. Based on DNMT3B promoter dual-luciferase reporter assay, we found PI3K pathway regulates DNMT3B expression at transcriptional level. And DNMT3B mRNA decay analysis suggested that down-regulation of DNMT3B by LY294002 is also post-transcriptional control. Furthermore, we demonstrated that LY294002 down-regulated HuR expression in a time-dependent manner in BEL-7404. In summary, we have, for the first time, demonstrate that PI3K/Akt pathway regulates the expression of DNMT3B at transcriptional and post-transcriptional levels, which is particularly important to understand the effects of PI3K/Akt and DNMT3B on hepatocarcinogenesis.

Ursolic acid, a naturally occurring triterpenoid, suppresses migration and invasion of human breast cancer cells by modulating c-Jun N-terminal kinase, Akt and mammalian target of rapamycin signaling

Metastasis is one of the most important factors related to breast cancer therapeutic efficacy. Ursolic acid, a naturally occurring triterpenoid, has various anticancer activities. In this study, we first observed that ursolic acid exerted a dose- and time-dependent inhibitory effect on the migration and invasion of highly metastatic breast MDAMB231 cells at non-cytotoxic concentrations. This effect was associated with reduced activities of metalloproteinase-2 (MMP-2) and u-PA, which correlated with enhanced expression of tissue inhibitor of MMP-2 and plasminogen activator inhibitor-1, respectively. Ursolic acid suppressed the phosphorylation of Jun N-terminal kinase, Akt and mammalian target of rapamycin, but had no effect on the phosphorylation of ERK and p38. Ursolic acid also strongly reduced the levels of NFkappaB p65, c-Jun and c-Fos proteins in the nucleus of MDAMB231 cells. A time-dependent inhibition of the protein levels of Rho-like GTPases, growth factor receptor-bound protein 2, Ras and vascular endothelial growth factor in cytosol by ursolic acid treatment was also observed. In conclusion, we demonstrated that the anti-invasive effects of ursolic acid on MDAMB231 cells might be through the inhibition of Jun N-terminal kinase, Akt and mammalian target of rapamycin phosphorylation and a reduction of the level of NFkappaB protein in the nucleus, ultimately leading to downregulation of MMP-2 and u-PA expression. These results suggest that ursolic acid has potential as a chemopreventive agent for metastatic breast cancer.

Low temperature of radiofrequency ablation at the target sites can facilitate rapid progression of residual hepatic VX2 carcinoma

Background

Rapid progression of residual tumor after radiofrequency ablation (RFA) of hepatocellular carcinoma has been observed increasingly. However, its underlying mechanisms remain to be clarified. The present study was designed to determine whether low temperature of RFA at the target sites facilitates rapid progression of residual hepatic VX2 carcinoma and to clarify the possible underlying mechanisms.

Methods

The residual VX2 hepatoma model in rabbits was established by using RFA at 55, 70 and 85°C. Rabbits that were implanted with VX2 hepatoma but did not receive RFA acted as a control group. The relationship between rapid progression of residual hepatic VX2 carcinoma and low temperature of RFA at the target sites was carefully evaluated. A number of potential contributing molecular factors, such as proliferating cell nuclear antigen (PCNA), matrix metalloproteinase 9 (MMP-9), vascular endothelial growth factor (VEGF), hepatocyte growth factor (HGF) and Interleukin-6 (IL-6) were measured.

Results

The focal tumor volume and lung metastases of RFA-treated rabbits increased significantly compared with the control group (P < 0.05), and the greatest changes were seen in the 55°C group (P < 0.05). Expression of PCNA, MMP-9, VEGF, HGF and IL-6 in tumor tissues increased significantly in the RFA-treated groups compared with the control group, and of the increases were greatest in the 55°C group (P < 0.05). These results were consistent with gross pathological observation. Tumor re-inoculation experiments confirmed that low temperature of RFA at the target sites facilitated rapid progression of residual hepatic VX2 carcinoma.

Conclusions

Insufficient RFA that is caused by low temperature at the target sites could be an important cause of rapid progression of residual hepatic VX2 carcinoma. Residual hepatic VX2 carcinoma could facilitate its rapid progression through inducing overexpression of several molecular factors, such as PCNA, MMP-9, VEGF, HGF and IL-6.

Lung cancer cell migration is regulated via repressing growth factor PTN/RPTP β/ζ signaling by menin

Menin encoded by the multiple endocrine neoplasia type 1 (MEN1) gene is associated with chromatin and the nuclear matrix and exerts multiple biological functions including regulation of cell proliferation and adhesion. Men1 mutations increase the likelihood of lung cancer development in mice. Menin expression is reduced in certain human non-small cell lung cancer cells, and reduction of menin is closely correlated with increased lung cancer metastasis to lymph nodes. However, it is poorly understood whether menin affects migration of lung cancer cells. In this study, we show that menin-regulated A549 lung cancer cell migration, which was mediated by growth factor pleiotrophin (PTN) and its cell surface receptor, protein tyrosine phosphatase beta/zeta (RPTP β/ζ). Ectopic menin expression significantly repressed PTN transcription, but indirectly inhibited RPTP β/ζ expression through repressing PTN expression. Further studies revealed that menin-regulated cell migration through PTN/RPTP β/ζ, in conjunction with integrin α_vβ₃, focal adhesion kinase, phosphatidylinositol 3-kinase and phosphorylated extracellular signal regulated kinase 1/2. These findings provide mechanistic insights into the molecular basis for menin/PTN-mediated regulation of A549 lung cancer cell migration.

Current status of molecularly targeted therapy for hepatocellular carcinoma: clinical practice

In recent years, molecular-targeted agents have been used clinically to treat various malignant tumors. In May 2009, sorafenib (Nexavar) was approved in Japan for "unresectable hepatocellular carcinoma (HCC)", and was the first molecular-targeted agent for use in liver cancer. To date, sorafenib is the only molecular-targeted agent whose survival benefit has been demonstrated in two global phase III randomized controlled trials, and it has now been approved worldwide. Phase III clinical trials are now underway to compare other molecular-targeted agents with sorafenib as first-line treatment agents, and to evaluate other multi-kinase inhibitors of the vascular endothelial growth factor and platelet-derived growth factor receptors, as well as drugs targeting the epidermal growth factor receptor, insulin-like growth factor receptor, and mammalian target of rapamycin, in addition to other molecules targeting other components of the signal transduction pathways. This review outlines the main pathways involved in the development and progression of HCC and the agents that target these pathways.

Coupling of mitochondria to store-operated Ca(2+)-signaling sustains constitutive activation of protein kinase B/Akt and augments survival of malignant melanoma cells

Mitochondria are emerging as a major hub for cellular Ca(2+)-signaling, though their contribution to Ca(2+)-driven growth- and survival-promoting events in cancer is poorly understood. Here employing flow cytometry to monitor mitochondrial and cytosolic Ca(2+), we assessed trans-mitochondrial Ca(2+)-transport and store-operated Ca(2+)-influx (store-operated channels (SOC)) in malignant vs. non-malignant B16BL6 melanoma clones. Remarkably, mitochondrial Ca(2+)-fluxes measured in whole cells or in isolated mitochondria were accelerated in the malignant clones compared to their non-malignant counterpart clones. This coincided with enhanced SOC-mediated Ca(2+)-influx and high levels of constitutively active protein kinase B/Akt (PKB). Interruption of trans-mitochondrial Ca(2+)-transport in the malignant cells with an antagonist of the mitochondrial Na(+)/Ca(2+) exchanger, CGP-37157, abolsihed SOC-mediated Ca(2+)-influx, inactivated PKB, retarded cell growth and increased vulnerability to apoptosis. Similarly, direct SOC blockade by silencing Stim1 inhibited PKB, indicating that the crosstalk between SOC and mitochondria is essential to preserve PKB in constitutively active state. Finally, the retraction of mitochondria from sub-plasmalemmal micro-domains triggered by Fis1 over-expression inhibited SOC-coupled trans-mitochondrial Ca(2+)-flux, Ca(2+)-entry via SOC and PKB activity. Taken together, our data show that in the malignant melanoma cells, the functional and spatial relationship of up-regulated mitochondrial Ca(2+)-transport to the SOC sustains the robust Ca(2+)-responses and down-stream signaling critical for apoptosis-resistance and proliferation.

FAK is involved in invasion and metastasis of hepatocellular carcinoma

Studies have shown that focal adhesion kinase (FAK) is overexpressed in several human tumors and plays an important role in tumor progression. However, the role and underlying mechanisms of FAK in hepatocellular carcinoma (HCC) progression remains to be elucidated. In this study, we examined FAK and phosphorylated FAK Tyr397 expression in a large series of HCCs. We found that both FAK and phosphorylated FAK Tyr397 were overexpressed in HCC samples and HCC cell lines. Increased FAK and phosphorylated FAK Tyr397 expressions were correlated with tumor stage, vascular invasion and intrahepatic metastasis in HCC. Furthermore, HCC cell adhesion, migration and invasion were substantially impaired by siRNA-mediated knockdown of FAK expression, whereas cell growth, apoptosis and cell cycle distribution were not affected. In addition, depletion of FAK induced a significant reduction in expressions and activities of both MMP-2 and MMP-9. Taken together, FAK contributes to invasion and metastasis of HCC partly through regulating expressions and activations of both MMP-2 and MMP-9, suggesting FAK could be a promising therapeutic target for HCC.

Clinical significance of miR-221 and its inverse correlation with p27Kip¹ in hepatocellular carcinoma

The aim of the present study is to explore possible role of miR-221 in the pathogenesis of HCC. Matched HCC and adjacent non-cancerous samples were assayed for the expression of miR-221 and three G1/S transition inhibitors: p27(Kip1), p21(WAF1/Cip1)and TGF-β1 by in situ hybridization and immunohistochemistry respectively. p27(Kip1) is one of miR-221's proven targets. Real time qRT-PCR was used to investigate miR-221 and p27(Kip1) transcripts in different clinical stages. Western blotting was used to analyze the expression levels of p27(Kip1) protein in different clinical stages. In result, miR-221 and TGF-β1 are frequently up-regulated in HCC, while p27(Kip1) and p21(WAF1/Cip1) proteins are frequently down-regulated. Moreover, miR-221 and p27(Kip1)'s expression correlated with metastasis and miR-221's expression also correlated with tumor size. Both of p21(WAF1/Cip1)and TGF-β1's expression correlated with tumor differentiations. miR-221's upregulation and p27(Kip1)'s downregulation were significantly associated with tumor stages and metastasis. In conclusion, miR-221 is important in tumorigenesis of HCC, possibly by specifically down-regulating p27(Kip1), a cell-cycle inhibitor. These results indicate miR-221 as a new therapeutic target in HCC.

MiR-222 overexpression confers cell migratory advantages in hepatocellular carcinoma through enhancing AKT signaling

PURPOSE

This study aims to profile the expressions of 156 microRNAs (miRNA) in hepatocellular carcinoma (HCC) and to characterize the functions of miR-222, the most significantly upregulated candidate identified.

EXPERIMENTAL DESIGN

miRNA expression profile in HCC tumors, matching adjacent cirrhotic livers, and cell lines was conducted using quantitative PCR. Common miR-222 upregulations were further validated in a larger cohort of tumors. The functional effects of miR-222 inhibition on HCC cell lines were examined. The downstream modulated pathways and target of miR-222 were investigated by coupling gene expression profiling and pathway analysis, and by in silico prediction, respectively. Luciferase reporter assay was done to confirm target interaction.

RESULTS

We identified a 40-miRNA signature that could discriminate tumors from adjacent cirrhotic liver tissue, and further corroborated common miR-222 overexpression in tumors relative to its premalignant counterpart (55.3%; P < 0.0001). Increased miR-222 expression correlated significantly with advanced stage HCC and with the shorter disease-free survival of patients (P < or = 0.01). Inhibition of miR-222 in Hep3B and HKCI-9 significantly retarded cell motility (P < 0.05). Further investigations suggested that AKT signaling was the major pathway influenced by miR-222. A consistent reduction of AKT phosphorylation in Hep3B and HKCI-9 was shown following miR-222 suppression. The protein phosphatase 2A subunit B (PPP2R2A) was predicted as a putative miR-222 target in silico. We found that miR-222 inhibition could augment the tumor protein level and restore luciferase activity in reporter construct containing the PPP2R2A 3' untranslated region (P = 0.0066).

CONCLUSIONS

Our study showed that miR-222 overexpression is common in HCC and could confer metastatic potentials in HCC cells, possibly through activating AKT signaling.

Rapamycin and CCI-779 inhibit the mammalian target of rapamycin signalling in hepatocellular carcinoma

BACKGROUND

The mammalian target of rapamycin (mTOR), which phosphorylates p70S6K and 4EBP1 and activates the protein translation process, is upregulated in cancers and its activation may be involved in cancer development.

AIMS

In this study, we investigated the tumour-suppressive effects of rapamycin and its new analogue CCI-779 on hepatocellular carcinoma (HCC).

METHODS

Rapamycin and its new analogue CCI-779 were applied to treat HCC cells. Cell proliferation, cell cycle profile and tumorigenicity were analysed.

RESULTS

In human HCCs, we observed frequent (67%, 37/55) overexpression of mTOR transcripts using real-time reverse transcriptase-polymerase chain reaction. Upon drug treatment, PLC/PRF/5 showed the greatest reduction in cell proliferation using the colony formation assay, as compared with HepG2, Hep3B and HLE. Rapamycin was a more potent antiproliferative agent than CCI-779 in HCC cell lines. Proliferation assays by cell counting showed that the IC(50) value of rapamycin was lower than that of CCI-779 in PLC/PRF/5 cells. Furthermore, flow cytometric analysis showed that both drugs could arrest HCC cells in the G(1) phase but did not induce apoptosis of these cells, suggesting that these mTOR inhibitors are cytostatic rather than cytotoxic. Upon rapamycin and CCI-779 treatment, the phosphorylation level of mTOR and p70S6K in HCC cell lines was significantly reduced, indicating that both drugs can suppress mTOR activity in HCC cells. In addition, both drugs significantly inhibited the growth of xenografts of PLC/PRF/5 cells in nude mice.

CONCLUSIONS

Our findings indicate that rapamycin and its clinical analogue CCI-779 possess tumour-suppressive functions towards HCC cells.

The genotypes of IL-1 beta and MMP-3 are associated with the prognosis of HCV-related hepatocellular carcinoma

BACKGROUND AND AIM

Cytokines and matrix metalloproteinases (MMPs) are involved in tumor growth, invasion, and remote metastasis in various cancers. Recently, functional gene polymorphisms in these cytokines and MMPs have been found, and some reports have revealed an association between these polymorphisms and the prognosis of various cancers. In this study, we examined the relationship between the gene polymorphisms of interleukin 1 beta (IL-1b), IL-1 receptor antagonist (IL-1 RN), transforming growth factor beta 1 (TGF-b1), MMP-1, MMP-3, and MMP-9 and the prognosis of hepatitis C virus (HCV)-related hepatocellular carcinoma (HCC).

METHODS

We enrolled 92 HCV-related HCC patients in the study, and gene polymorphisms of IL-1b -31 C/T, IL-1 RN variable number of tandem repeats (VNTR), TGF-b1 +869 C/T, MMP-1 -1,607 1G/2G, MMP-3 -1,171 5A/6A, and MMP-9 -1,562 C/T were analyzed.

RESULTS

In HCC clinical features, TGF-b1 C carriers and MMP-3 5A carriers had significantly larger HCC diameters than TGF-b1 T and MMP-3 6A homozygotes. In HCC prognosis, IL-1b T homozygotes and MMP-3 5A carriers had a significantly poorer prognosis than IL-1b C carriers and MMP-3 6A homozygotes. Those with a combination of IL-1b T homozygosity and MMP-3 5A had synergistically poorer HCC prognosis.

CONCLUSION

The IL-1b -31 T allele and MMP-3 5A allele are cooperative risk factors for poor prognosis in HCC patients, suggesting that these gene polymorphisms might be potential markers for predicting the prognosis of HCC patients.

MicroRNAs: target recognition and regulatory functions

MicroRNAs (miRNAs) are endogenous approximately 23 nt RNAs that play important gene-regulatory roles in animals and plants by pairing to the mRNAs of protein-coding genes to direct their posttranscriptional repression. This review outlines the current understanding of miRNA target recognition in animals and discusses the widespread impact of miRNAs on both the expression and evolution of protein-coding genes.