Activation of Sphingomyelin Phosphodiesterase 3 in Liver Regeneration Impedes the Progression of Colorectal Cancer Liver Metastasis Via Exosome-Bound Intercellular Transfer of Ceramides.

BACKGROUND & AIMS: The machinery that prevents colorectal cancer liver metastasis (CRLM) in the context of liver regeneration (LR) remains elusive. Ceramide (CER) is a potent anti-cancer lipid involved in intercellular interaction. Here, we investigated the role of CER metabolism in mediating the interaction between hepatocytes and metastatic colorectal cancer (CRC) cells to regulate CRLM in the context of LR. METHODS: Mice were intrasplenically injected with CRC cells. LR was induced by 2/3 partial hepatectomy (PH) to mimic the CRLM in the context of LR. The alteration of corresponding CER-metabolizing genes was examined. The biological roles of CER metabolism in vitro and in vivo were examined by performing a series of functional experiments. RESULTS: Induction of LR augmented apoptosis but promoted matrix metalloproteinase 2 (MMP2) expression and epithelial-mesenchymal transition (EMT) to increase the invasiveness of metastatic CRC cells, resulting in aggressive CRLM. Up-regulation of sphingomyelin phosphodiesterase 3 (SMPD3) was determined in the regenerating hepatocytes after LR induction and persisted in the CRLM-adjacent hepatocytes after CRLM formation. Hepatic Smpd3 knockdown was found to further promote CRLM in the context of LR by abolishing mitochondrial apoptosis and augmenting the invasiveness in metastatic CRC cells by up-regulating MMP2 and EMT through promoting the nuclear translocation of ß-catenin. Mechanistically, we found that hepatic SMPD3 controlled the generation of exosomal CER in the regenerating hepatocytes and the CRLM-adjacent hepatocytes. The SMPD3-produced exosomal CER critically conducted the intercellular transfer of CER from the hepatocytes to metastatic CRC cells and impeded CRLM by inducing mitochondrial apoptosis and restricting the invasiveness in metastatic CRC cells. The administration of nanoliposomal CER was found to suppress CRLM in the context of LR substantially. CONCLUSIONS: SMPD3-produced exosomal CER constitutes a critical anti-CRLM mechanism in LR to impede CRLM, offering the promise of using CER as a therapeutic agent to prevent the recurrence of CRLM after PH.

Tumor-derived exosomal miR-1247-3p induces cancer-associated fibroblast activation to foster lung metastasis of liver cancer.

The communication between tumor-derived elements and stroma in the metastatic niche has a critical role in facilitating cancer metastasis. Yet, the mechanisms tumor cells use to control metastatic niche formation are not fully understood. Here we report that in the lung metastatic niche, high-metastatic hepatocellular carcinoma (HCC) cells exhibit a greater capacity to convert normal fibroblasts to cancer-associated fibroblasts (CAFs) than low-metastatic HCC cells. We show high-metastatic HCC cells secrete exosomal miR-1247-3p that directly targets B4GALT3, leading to activation of ß1-integrin-NF-κB signaling in fibroblasts. Activated CAFs further promote cancer progression by secreting pro-inflammatory cytokines, including IL-6 and IL-8. Clinical data show high serum exosomal miR-1247-3p levels correlate with lung metastasis in HCC patients. These results demonstrate intercellular crosstalk between tumor cells and fibroblasts is mediated by tumor-derived exosomes that control lung metastasis of HCC, providing potential targets for prevention and treatment of cancer metastasis.

Aldehyde dehydrogenase-2 (ALDH2) opposes hepatocellular carcinoma progression by regulating AMP-activated protein kinase signaling in mice.

Potential biomarkers that can be used to determine prognosis and perform targeted therapies are urgently needed to treat patients with hepatocellular carcinoma (HCC). To meet this need, we performed a screen to identify functional genes associated with hepatocellular carcinogenesis and its progression at the transcriptome and proteome levels. We identified aldehyde dedydrogenase-2 (ALDH2) as a gene of interest for further study. ALDH2 levels were significantly lower at the mRNA and protein level in tumor tissues than in normal tissues, and they were even lower in tissues that exhibited increased migratory capacity. A study of clinical associations showed that ALDH2 is correlated with survival and multiple migration-associated clinicopathological traits, including the presence of metastasis and portal vein tumor thrombus. The result of overexpressing or knocking down ALDH2 showed that this gene inhibited migration and invasion both in vivo and in vitro. We also found that ALDH2 altered the redox status of cells by regulating acetaldehyde levels and that it further activated the AMP-activated protein kinase (AMPK) signaling pathway. CONCLUSION: Decreased levels of ALDH2 may indicate a poor prognosis in HCC patients, while forcing the expression of ALDH2 in HCC cells inhibited their aggressive behavior in vitro and in mice largely by modulating the activity of the ALDH2-acetaldehyde-redox-AMPK axis. Therefore, identifying ALDH2 expression levels in HCC might be a useful strategy for classifying HCC patients and for developing potential therapeutic strategies that specifically target metastatic HCC. (Hepatology 2017;65:1628-1644).

Bif-1 promotes tumor cell migration and metastasis via Cdc42 expression and activity.

Tumor metastasis is the process by which tumor cells disseminate from tumors and enter nearby and distant microenvironments for new colonization. Bif-1 (BAX-interacting factor 1), which has a BAR domain and an SH3 domain, has been reported to be involved in cell growth, apoptosis and autophagy. However, the influence of Bif-1 on metastasis has been less studied. To understand the role of Bif-1 in metastasis, we studied the expression levels of Bif-1 in human HCC specimens using immunohistochemistry, a tissue microarray and quantitative PCR. The function of Bif-1 was assessed in migration and translocation assays and the pulmonary metastatic animal model. The relationship between Bif-1 and the Rho family was determined using immunoblot analyses and chromatin immunoprecipitation. The results showed that the expression of Bif-1 was higher in hepatocellular carcinoma (HCC) than matched adjacent non-tumor liver tissues. Increased Bif-1 expression was associated with tumor size and the intercellular spread and metastasis of HCC. Analysis of the relationship between Bif-1 expression and patients' clinical characteristics revealed that patients with higher levels of Bif-1 had shorter disease-free and overall survival rates. Knockdown of Bif-1 with RNAi suppressed the migration of HCC cells and pulmonary metastasis and decreased the expression of Cdc42, a member of the Rho family. Bif-1 localized to the cytosol and nucleus and interacted with the promoter transcription region of Cdc42, which may regulate Cdc42 expression. Our results demonstrate a novel role of Bif-1 in HCC, in which Bif-1 promotes cell metastasis by regulating Cdc42 expression and activity.

Musashi 2 contributes to the stemness and chemoresistance of liver cancer stem cells via LIN28A activation.

Accumulating evidence suggests that cancer stem cells (CSCs), a small subset of cancer cells, are responsible for tumor initiation, progression, relapse and metastasis. Musashi 2 (MSI2), a RNA-binding protein, was proposed to be a potent oncogene playing key roles in myeloid leukemia and gastrointestinal malignancies. However, it remains elusive how MSI2 regulates stem cell features in HCC. Herein, we demonstrated that MSI2 was highly expressed in liver CSCs. Overexpression or knockdown of MSI2 altered CSC-related gene expression, self-renewal as well as resistance to chemotherapy in HCC cell lines. In mouse xenograft models, MSI2 could markedly enhance tumorigenicity. Mechanistically, overexpression of MSI2 resulted in the upregulation of Lin28A. Stemness and chemotherapeutic drug resistance induced by MSI2 overexpression were dramatically reduced by Lin28A knockdown. Moreover, MSI2 and LIN28A levels positively correlated with the clinical severity and prognosis in HCC patients. In conclusion, MSI2 might play a crucial role in sustaining stemness and chemoresistance of liver CSCs via LIN28A-dependent manner in HCC. Our findings revealed that MSI2 and Lin28A might be used as potential therapeutic targets for eradicating liver CSCs.

ADRB2 signaling promotes HCC progression and sorafenib resistance by inhibiting autophagic degradation of HIF1α.

BACKGROUND & AIMS: Considerable evidence suggests that adrenergic signaling played an essential role in tumor progression. However, its role in hepatocellular carcinoma (HCC) and the underlying mechanisms remain unknown. METHODS: The effect of adrenaline in hepatocarcinogenesis was observed in a classical diethylnitrosamine-induced HCC mouse model. Effects of ADRB2 signaling inhibition in HCC cell lines were analyzed in proliferation, apoptosis, colony formation assays. Autophagy regulation by ADRB2 was assessed in immunoblotting, immunofluorescence and immunoprecipitation assays. In vivo tumorigenic properties and anticancer effects of sorafenib were examined in nude mice. Expression levels of ADRB2 and hypoxia-inducible factor-1α (HIF1α) in 150 human HCC samples were evaluated by immunohistochemistry. RESULTS: We uncovered that adrenaline promoted DEN-induced hepatocarcinogenesis, which was reversed by the ADRB2 antagonist ICI118,551. ADRB2 signaling also played an essential role in sustaining HCC cell proliferation and survival. Notably, ADRB2 signaling negatively regulated autophagy by disrupting Beclin1/VPS34/Atg14 complex in an Akt-dependent manner, leading to HIF1α stabilization, reprogramming of HCC cells glucose metabolism, and the acquisition of resistance to sorafenib. Conversely, inhibition of ADRB2 signaling by ICI118,551, or knockdown ADRB2 expression, led to enhanced autophagy, HIF1α destabilization, tumor growth suppression, and improved anti-tumor activity of sorafenib. Consistently, ADRB2 expression correlated positively with HIF1α in HCC specimens and was associated with HCC outcomes. CONCLUSIONS: Our results uncover an important role of ADRB2 signaling in regulating HCC progression. Given the efficacy of ADRB2 modulation on HCC inhibition and sorafenib resistance, adrenoceptor antagonist appears to be a putative novel treatment for HCC and chemoresistance. LAY SUMMARY: ADRB2 signaling played an essential role in sustaining hepatocellular carcinoma cell proliferation and survival. ADRB2 signaling negatively regulated autophagy, leading to hypoxia-inducible factor-1α stabilization, reprogramming of hepatocellular carcinoma cells glucose metabolism, and the acquisition of resistance to sorafenib. Adrenoceptor antagonist appears to be a putative novel treatment for hepatocellular carcinoma and chemoresistance.

Interferon-microRNA signalling drives liver precancerous lesion formation and hepatocarcinogenesis.

OBJECTIVE: Precancerous lesion, a well-established histopathologically premalignant tissue with the highest risk for tumourigenesis, develops preferentially from activation of DNA damage checkpoint and persistent inflammation. However, little is known about the mechanisms by which precancerous lesions are initiated and their physiological significance. DESIGN: Laser capture microdissection was used to acquire matched normal liver, precancerous lesion and tumour tissues. miR-484(-/-), Ifnar1(-/-) and Tgfbr2(△hep) mice were employed to determine the critical role of the interferon (IFN)-microRNA pathway in precancerous lesion formation and tumourigenesis. RNA immunoprecipitation (RIP), pull-down and chromatin immunoprecipitation (ChIP) assays were applied to explore the underlying mechanisms. RESULTS: miR-484 is highly expressed in over 88% liver samples clinically. DEN-induced precancerous lesions and hepatocellular carcinoma were dramatically impaired in miR-484(-/-) mice. Mechanistically, ectopic expression of miR-484 initiates tumourigenesis and cell malignant transformation through synergistic activation of the transforming growth factor-ß/Gli and nuclear factor-κB/type I IFN pathways. Specific acetylation of H3K27 is indispensable for basal IFN-induced continuous transcription of miR-484 and cell transformation. Convincingly, formation of precancerous lesions were significantly attenuated in both Tgfbr2(△hep) and Ifnar1(-/-) mice. CONCLUSIONS: These findings demonstrate a new protumourigenic axis involving type I IFN-microRNA signalling, providing a potential therapeutic strategy to manipulate or reverse liver precancerous lesions and tumourigenesis.

HBx regulates fatty acid oxidation to promote hepatocellular carcinoma survival during metabolic stress.

Due to a high rate of nutrient consumption and inadequate vascularization, hepatocellular carcinoma (HCC) cells constantly undergo metabolic stress during tumor development. Hepatitis B virus (HBV) X protein (HBx) has been implicated in the pathogenesis of HBV-induced HCC. In this study, we investigated the functional roles of HBx in HCC adaptation to metabolic stress. Up-regulation of HBx increased the intracellular ATP and NADPH generation, and induced the resistance to glucose deprivation, whereas depletion of HBx via siRNA abolished these effects and conferred HCC cells sensitive to glucose restriction. Though HBx did not affect the glycolysis and oxidative phosphorylation capacity of HCC cells under normal culture conditions, it facilitated fatty acid oxidation (FAO) in the absence of glucose, which maintained NADPH and ATP levels. Further investigation showed that HBx expression, under glucose deprivation, stimulated phosphorylation of AMP-activated protein kinase (AMPK) and acetyl-CoA carboxylase (ACC) via a calcium/CaMKK-dependent pathway, which was required for the activation of FAO. Conversely, inhibition of FAO by etomoxir (ETO) restored the sensitivity of HBx-expressing cells to glucose deficiency in vitro and retarded xenograft tumor formation in vivo. Finally, HBx-induced activation of the AMPK and FAO pathways were also observed in xenograft tumors and HBV-associated HCC specimens. Our data suggest that HBx plays a key role in the maintenance of redox and energy homeostasis by activating FAO, which is critical for HCC cell survival under conditions of metabolic stress and might be exploited for therapeutic benefit.

A20 suppresses hepatocellular carcinoma proliferation and metastasis through inhibition of Twist1 expression.

BACKGROUND: Aberrant expression of A20 has been reported in several human malignancies including hepatocellular carcinoma (HCC). However, its clinical relevance and potential role in HCC remain unknown. METHODS: Quantitative PCR, Western blots and immunohistochemistry analyses were used to quantify A20 expression in HCC samples and cell lines. The correlation of A20 expression with clinicopathologic features was analyzed in a cohort containing 143 patients with primary HCC. Kaplan-Meier curves were used to evaluate the association between A20 expression and patient survival. Functional studies were performed to determine the effects of A20 on proliferation and metastasis of HCC cells in vitro and in vivo. RESULTS: Expression of A20 was increased in HCC tissues and cell lines. Increased expression of A20 was negatively correlated with the tumor size, TNM stage, tumor thrombus formation, capsular invasion and serum AFP levels. Patients with higher A20 expression had a prolonged disease-free survival and overall survival than those with lower A20 expression. Forced expression of A20 significantly inhibited the proliferative and invasive properties of HCC cells both in vitro and in vivo, whereas knockdown of A20 expression showed the opposite effects. Further studies revealed that expression of A20 was inversely correlated with Twist1 levels and NF-κB activity in HCC tissues and cell lines. A20-induced suppression of proliferation and migration of HCC cells were mainly mediated through inhibition of Twist1 expression that was regulated at least partly by A20-induced attenuation of NF-κB activity. CONCLUSIONS: Our results demonstrate that A20 plays a negative role in the development and progression of HCC probably through inhibiting Twist1 expression. A20 may serve as a novel prognostic biomarker and potential therapeutic target for HCC patients.

MiR-429 increases the metastatic capability of HCC via regulating classic Wnt pathway rather than epithelial-mesenchymal transition.

Epigenetic modification of miR-429 can manipulate liver T-ICs via targeting the RBBP4/E2F1/Oct4 axis, which might be crucial for hepatocarcinogenesis. However, whether miR-429 plays a role in regulating metastasis of hepatocellular carcinoma is still unclear. Using quantitative methylation analysis and real-time PCR, we have identified the hypomethylated status and upregulation of miR-429 in portal vein metastasis samples in comparison with their matched primary tumor. The ectopic expression of miR-429 dramatically induced the expression of MMP2/7/9 and enhanced HCC migration and invasion in vitro and in vivo in an EMT-independent manner. Both bioinformatics and functional studies elucidated the direct regulation of miR-429 on the 3'UTR of the PTEN gene, which leads to the activation of PI3K/AKT signaling and the nuclear translocation of ß-catenin, eventually. Conversely, the knockdown of miR-429 efficiently recovered the expression of PTEN and attenuated PI3K/AKT/ß-catenin-mediated cell metastasis. Clinically, the higher expression of miR-429 and nucleus relocation of ß-catenin were identified as the adverse prognosis factors for recurrence-free survival (RFS) and overall survival (OS). In summary, our results here defined miR-429 as a key inducer for HCC pathogenesis and metastasis with potential utility for tumor intervention.

p28GANK inhibits endoplasmic reticulum stress-induced cell death via enhancement of the endoplasmic reticulum adaptive capacity.

It has been shown that oncoprotein p28(GANK), which is consistently overexpressed in human hepatocellular carcinoma (HCC), plays a critical role in tumorigenesis of HCC. However, the underlying mechanism remains unclear. Here, we demonstrated that p28(GANK) inhibits apoptosis in HCC cells induced by the endoplasmic reticulum (ER) stress. During ER stress, p28(GANK) enhances the unfolded protein response, promotes ER recovery from translational repression, and thereby facilitates cell's ability to cope with the stress conditions. Furthermore, p28(GANK) upregulates glucose-regulated protein 78 (GRP78), a key ER chaperone protein, which subsequently enhances the ER folding capacity and promotes recovery from ER stress. We also demonstrated that p28(GANK) increases p38 mitogen-activated protein kinase and Akt phosphorylation, and inhibits nuclear factor kappa B (NF-kappaB) activation under ER stress, which in turn contributes to GRP78 upregulation. Taken together, our results indicate that p28(GANK) inhibits ER stress-induced apoptosis in HCC cells, at least in part, by enhancing the adaptive response and GRP78 expression. We propose that p28(GANK) has potential implications for HCC progression under the ER stress conditions.

p28GANK knockdown-derived reactive oxygen species induces apoptosis through mitochondrial dysfunction mediated by p38 in HepG2 cells.

Oncoprotein p28GANK knockdown by RNA interference (RNAi) can induce hepatoma cells apoptosis. However, the mechanisms have not been well defined yet. In the present study the p28GANK knockdown-induced apoptosis in HepG2 cells was prevented by caspase-9 inhibitor (Z-LEHD-FMK). During the knockdown of p28GANK, mitochondrial translocation of Bax, loss of mitochondrial transmembrane potential (DeltaPsim) and release of cytochrome c were observed. In this study, the activation of p38 was found to be critical for the p28GANK knockdown-induced apoptosis, as suggested by the finding that pharmacological inhibition of p38 with SB203580 suppressed the redistribution of Bax, the loss of DeltaPsim and the apoptosis. Moreover, generation of reactive oxygen species (ROS) contributed to the cell death because N-acetyl-L-cystenine (NAC), a ROS scavenger, suppressed the phosphorylation of p38 and the apoptosis. Our studies established the signaling pathway of p28GANK knockdown-induced apoptosis in HepG2 cells, namely, mitochondrial dysfunction mediated by p38 downstream of intracellular ROS generation.

[Preparation of plastic nano-hydroxyapatite/poly (3-hydroxybutyrate-hydroxyvalerate)-polymethyl lene glycol gentamicin drug delivery system].

OBJECTIVE: To develop the plastic nano-hydroxyapatite (nano-HA)/poly (3-hydroxybutyrate-hydroxyvalerate)-polyethylene glycol (PHBV-PEG) gentamicin (GM) drug delivery system (DDS) (nano-HA/PHBV-PEG-GM-DDS) for treating osteomyelitis and find its releasing character in vivo. METHODS: The plastic nano-HA/PHBV-PEG-GM-DDS was prepared using nano-HA as the core carrier of GM, nano-HA with PHBV and PEG as coating and plastic fibrin glue(FG) as microsphere scaffold. The morphological features of nano-HA, drug loaded nano-HA and drug loaded nano-HA/PHBV-PEG microsphere were examined by electron microscope. The GM concentration it blood, cortex bone and cancellous bone was detected at 12 different time points by the method of K-B after the plastic nano-HA/PHBV-PEG-GM-DDS was implanted into the femora of 36 rabbits. Its GM releasing character was assayed in vivo. RESULTS: Nano-HA was similar to a blackjack, and its length was less than 60 nm. Drug loaded nano-HA appeared natural crystal condensate, of which surface adsorbed massive GM. The average grain diameter was 200.5 nm. Drug loaded nano-HA/PHBV-PEG microsphere had a shrinkable porous structure, of which surface configuration was consistent. The average grain diameter was 34.5 microm. The GM concentration and the antibacterial annulus was in the linear correlation. The correlation coefficient was 0.998. In cortex and cancellous bone tissue, the GM concentration was about 95.50 +/- 16.50 microg/ml and 80.20 +/- 13.80 microg/ml from the plastic nano-HA/PHBV-PEG-GM-DDS on the 1st day, then decreased gradually. After 56 days of operation, the GM concentration still exceeded the minimum inhibitory concentration for the staphylococcus aureus, but the peak level of serum GM concentration was under the nephrotoxicity concentration. CONCLUSION: Plastic nano-HA/PHBV-PEG-GM-DDS was a good drug delivery system with sustained antibiotic effect in vivo. It was an effective method for the treatment of osteomyelitis.

[Development of an anti-infection nano-hydroxypatite drug delivery microsphere and its drug-release in vitro].

OBJECTIVE: To develop an anti-infection nano-hydroxypatite (nano-HA) microsphere for local drug delivery for treating osteomyelitis. METHODS: The nano-HA was used as the core carrier to load gentamicin (GM) and coated with poly(-hydroxybutyrate-co- hydroxyvalerate)/polyethylene glycol (PHBV/PEG), which was degradable and biocompatible, to prepare nano-HA-PHBV/PEG-GM microsphere. The surface structure and in vitro drug-release of the microsphere were studied. RESULTS: The microsphere had good drug delivery capability. The samples weighing 90 mg each were soaked in PBS and gentamicin release within the first day was 165.2 microg/ml, which maintained a low release rate in the following days. After 28 days, gentamicin release declined to 8.5 microg/ml, which was higher than the minimal inhibitory concentration of gentamicin (2 microg/ml). CONCLUSION: The local drug delivery system has good drug-release performance in vitro and may possess potential value in clinical management of osteomyelitis.