Increased vascular permeability facilitates metastasis. Emerging evidence indicates that secreted microRNAs (miRNAs) may mediate the crosstalk between cancer and stromal cells. To date, whether and ...how secreted miRNAs affect vascular permeability remains unclear. Based on deep sequencing and quantitative PCR, we found that higher level of serum miR‐103 was associated with higher metastasis potential of hepatocellular carcinoma (HCC). The in vitro endothelial permeability and transendothelial invasion assays revealed that the conditioned media or exosomes derived from high miR‐103‐expressing hepatoma cells increased the permeability of endothelial monolayers, but this effect was attenuated if exosome secretion of hepatoma cells was blocked by silencing ALIX and HRS or if miR‐103 within hepatoma or endothelial cells was antagonized. Most importantly, pretreating endothelial monolayers with exosomes that were from stable miR‐103‐expressing hepatoma cells facilitated the transendothelial invasion of tumor cells, and this role of exosomes was abrogated by inhibiting miR‐103 in endothelial cells. Further in vivo analyses disclosed that mice with xenografts of stable miR‐103‐expressing hepatoma cells exhibited higher vascular permeability in tumor, higher level of exosomal miR‐103 and greater number of tumor cells in blood circulation, and increased rates of hepatic and pulmonary metastases, compared to control mice. Mechanism investigations revealed that hepatoma cell‐secreted miR‐103 could be delivered into endothelial cells via exosomes, and then attenuated the endothelial junction integrity by directly inhibiting the expression of VE‐Cadherin (VE‐Cad), p120‐catenin (p120) and zonula occludens 1. Moreover, miR‐103 could also promote tumor cell migration by repressing p120 expression in hepatoma cells. Conclusion: Hepatoma cell‐secreted exosomal miR‐103 increases vascular permeability and promotes tumor metastasis by targeting multiple endothelial junction proteins, which highlights secreted miR‐103 as a potential therapeutic target and a predictive marker for HCC metastasis. (Hepatology 2018).
Background and Aims
DNA damage‐induced NF‐κB activation is a major obstacle to effective antitumour chemotherapy. Long noncoding RNAs (lncRNAs) that regulate chemoresistance of cancer cells remain ...largely unknown. This study aimed to characterize the lncRNAs that may affect chemotherapy sensitivity.
Approach and Results
We found that lncRNA PDIA3P1 (protein disulfide isomerase family A member 3 pseudogene 1) was up‐regulated in multiple cancer types and following treatment with DNA‐damaging chemotherapeutic agents, like doxorubicin (Dox). Higher PDIA3P1 level was associated with poorer recurrence‐free survival of human hepatocellular carcinoma (HCC). Both gain‐of‐function and loss‐of‐function studies revealed that PDIA3P1 protected cancer cells from Dox‐induced apoptosis and allowed tumor xenografts to grow faster and to be more resistant to Dox treatment. Mechanistically, miR‐125a/b and miR‐124 suppressed the expression of tumor necrosis factor receptor‐associated factor 6 (TRAF6), but PDIA3P1 bound to miR‐125a/b/miR‐124 and relieved their repression on TRAF6, leading to activation of the nuclear factor kappa B (NF‐κB) pathway. Consistently, the effect of PDIA3P1 inhibition in promoting Dox‐triggered apoptosis was antagonized by silencing the inhibitor of κBα (IκBα) or overexpressing TRAF6. Administration of BAY 11‐7085, an NF‐κB inhibitor attenuated PDIA3P1‐induced resistance to Dox treatment in mouse xenografts. Moreover, up‐regulation of PDIA3P1 was significantly correlated with elevation of TRAF6, phosphorylated p65, or NF‐κB downstream anti‐apoptosis genes in human HCC tissues. These data indicate that enhanced PDIA3P1 expression may confer chemoresistance by acting as a microRNA sponge to increase TRAF6 expression and augment NF‐κB signaling. Subsequent investigations into the mechanisms of PDIA3P1 up‐regulation revealed that human homologue of mRNA transport mutant 4 (hMTR4), which promotes RNA degradation, could bind to PDIA3P1, and this interaction was disrupted by Dox treatment. Overexpression of hMTR4 attenuated Dox‐induced elevation of PDIA3P1, whereas silencing hMTR4 increased PDIA3P1 level, suggesting that Dox may up‐regulate PDIA3P1 by abrogating the hMTR4‐mediated PDIA3P1 degradation.
Conclusion
There exists a hMTR4‐PDIA3P1‐miR‐125/124‐TRAF6 regulatory axis that regulates NF‐κB signaling and chemoresistance, which may be exploited for anticancer therapy.
Based on microarray data, we have previously shown a significant down‐regulation of miR‐29 in hepatocellular carcinoma (HCC) tissues. To date, the role of miR‐29 deregulation in hepatocarcinogenesis ...and the signaling pathways by which miR‐29 exerts its function and modulates the malignant phenotypes of HCC cells remain largely unknown. In this study, we confirmed that reduced expression of miR‐29 was a frequent event in HCC tissues using both Northern blot and real‐time quantitative reverse‐transcription polymerase chain reaction. More interestingly, we found that miR‐29 down‐regulation was significantly associated with worse disease‐free survival of HCC patients. Both gain‐ and loss‐of‐function studies revealed that miR‐29 could sensitize HCC cells to apoptosis that was triggered by either serum starvation and hypoxia or chemotherapeutic drugs, which mimicked the tumor growth environment in vivo and the clinical treatment. Moreover, introduction of miR‐29 dramatically repressed the ability of HCC cells to form tumor in nude mice. Subsequent investigation characterized two antiapoptotic molecules, Bcl‐2 and Mcl‐1, as direct targets of miR‐29. Furthermore, silencing of Bcl‐2 and Mcl‐1 phenocopied the proapoptotic effect of miR‐29, whereas overexpression of these proteins attenuated the effect of miR‐29. In addition, enhanced expression of miR‐29 resulted in the loss of mitochondrial potential and the release of cytochrome c to cytoplasm, suggesting that miR‐29 may promote apoptosis through a mitochondrial pathway that involves Mcl‐1 and Bcl‐2. Conclusion: Our data highlight an important role of miR‐29 in the regulation of apoptosis and in the molecular etiology of HCC, and implicate the potential application of miR‐29 in prognosis prediction and in cancer therapy. (HEPATOLOGY 2010.)
Although thousands of long noncoding RNAs (lncRNAs) have been annotated, only a limited number of them have been functionally characterized. Here, we identified an oncogenic lncRNA, named lnc‐UCID ...(lncRNA up‐regulating CDK6 by interacting with DHX9). Lnc‐UCID was up‐regulated in hepatocellular carcinoma (HCC), and a higher lnc‐UCID level was correlated with shorter recurrence‐free survival of HCC patients. Both gain‐of‐function and loss‐of function studies revealed that lnc‐UCID enhanced cyclin‐dependent kinase 6 (CDK6) expression and thereby promoted G1/S transition and cell proliferation. Studies from mouse xenograft models revealed that tumors derived from lnc‐UCID‐silenced HCC cells had a much smaller size than those from control cells, and intratumoral injection of lnc‐UCID small interfering RNA suppressed xenograft growth. Mechanistically, the 850‐1030‐nt domain of lnc‐UCID interacted physically with DEAH (Asp‐Glu‐Ala‐His) box helicase 9 (DHX9), an RNA helicase. On the other hand, DHX9 post‐transcriptionally suppressed CDK6 expression by binding to the 3′‐untranslated region (3′UTR) of CDK6 mRNA. Further investigation disclosed that lnc‐UCID enhanced CDK6 expression by competitively binding to DHX9 and sequestering DHX9 from CDK6‐3′UTR. In an attempt to explore the mechanisms responsible for lnc‐UCID up‐regulation in HCC, we found that the lnc‐UCID gene was frequently amplified in HCC. Furthermore, miR‐148a, whose down‐regulation was associated with an increase of lnc‐UCID in HCC, could bind lnc‐UCID and inhibit its expression. Conclusion: Up‐regulation of lnc‐UCID, which may result from amplification of its gene locus and down‐regulation of miR‐148a, can promote HCC growth by preventing the interaction of DHX9 with CDK6 and subsequently enhancing CDK6 expression. These findings provide insights into the biological functions of lncRNAs, the regulatory network of cell cycle control, and the mechanisms of HCC development, which may be exploited for anticancer therapy.
Hepatocellular carcinoma (HCC) is characterized by active angiogenesis and metastasis, which account for rapid recurrence and poor survival. There is frequent down‐regulation of miR‐195 expression in ...HCC tissues. In this study, the role of miR‐195 in HCC angiogenesis and metastasis was investigated with in vitro capillary tube formation and transwell assays, in vivo orthotopic xenograft mouse models, and human HCC specimens. Reduction of miR‐195 in HCC tissues was significantly associated with increased angiogenesis, metastasis, and worse recurrence‐free survival. Both gain‐of‐function and loss‐of‐function studies of in vitro models revealed that miR‐195 not only suppressed the ability of HCC cells to promote the migration and capillary tube formation of endothelial cells but also directly repressed the abilities of HCC cells to migrate and invade extracellular matrix gel. Based on mouse models, we found that the induced expression of miR‐195 dramatically reduced microvessel densities in xenograft tumors and repressed both intrahepatic and pulmonary metastasis. Subsequent investigations disclosed that miR‐195 directly inhibited the expression of the proangiogenic factor vascular endothelial growth factor (VEGF) and the prometastatic factors VAV2 and CDC42. Knockdown of these target molecules of miR‐195 phenocopied the effects of miR‐195 restoration, whereas overexpression of these targets antagonized the function of miR‐195. Furthermore, we revealed that miR‐195 down‐regulation resulted in enhanced VEGF levels in the tumor microenvironment, which subsequently activated VEGF receptor 2 signaling in endothelial cells and thereby promoted angiogenesis. Additionally, miR‐195 down‐regulation led to increases in VAV2 and CDC42 expression, which stimulated VAV2/Rac1/CDC42 signaling and lamellipodia formation and thereby facilitated the metastasis of HCC cells. Conclusion: miR‐195 deregulation contributes to angiogenesis and metastasis in HCC. The restoration of miR‐195 expression may be a promising strategy for HCC therapy. (Hepatology 2013;58:642‐653)
Sorafenib is the most recommended first‐line systemic therapy for advanced hepatocellular carcinoma (HCC). Yet there is no clinically applied biomarker for predicting sorafenib response. We have ...demonstrated that a vascular pattern, named VETC (Vessels that Encapsulate Tumor Clusters), facilitates the release of whole tumor clusters into the bloodstream; VETC‐mediated metastasis relies on vascular pattern, but not on migration and invasion of cancer cells. In this study, we aimed to explore whether vascular pattern could predict sorafenib benefit. Two cohorts of patients were recruited from four academic hospitals. The survival benefit of sorafenib treatment for patients with or without the VETC pattern (VETC+/VETC–) was investigated. Kaplan‐Meier analyses revealed that sorafenib treatment significantly reduced death risk and prolonged overall survival (OS; in cohort 1/2, P = 0.004/0.005; hazard ratio HR = 0.567/0.408) and postrecurrence survival (PRS; in cohort 1/2, P = 0.001/0.002; HR = 0.506/0.384) in VETC+ patients. However, sorafenib therapy was not beneficial for VETC‐ patients (OS in cohort 1/2, P = 0.204/0.549; HR = 0.761/1.221; PRS in cohort 1/2, P = 0.121/0.644; HR = 0.728/1.161). Univariate and multivariate analyses confirmed that sorafenib treatment significantly improved OS/PRS in VETC+, but not VETC–, patients. Further mechanistic investigations showed that VETC+ and VETC– HCCs displayed similar levels of light chain 3 (LC3) and phosphorylated extracellular signal‐regulated kinase (ERK) in tumor tissues (pERK) or endothelial cells (EC‐pERK), and greater sorafenib benefit was consistently observed in VETC+ HCC patients than VETC– irrespective of levels of pERK/EC‐pERK/LC3, suggesting that the different sorafenib benefit between VETC+ and VETC– HCCs may not result from activation of Raf/mitogen‐activated protein kinase kinase (MEK)/ERK and vascular endothelial growth factor (VEGF)A/VEGF receptor 2 (VEGFR2)/ERK signaling or induction of autophagy. Conclusion: Sorafenib is effective in prolonging the survival of VETC+, but not VETC–, patients. VETC pattern may act as a predictor of sorafenib benefit for HCC.
Early metastasis is responsible for frequent relapse and high mortality of hepatocellular carcinoma (HCC), but its underlying mechanisms remain unclear. Epithelial–mesenchymal transition (EMT) has ...been considered a key event in metastasis. Based on histological examination of serial HCC sections and three‐dimensional reconstruction, we found a novel and prevalent vascular pattern, vessels that encapsulated tumor clusters (VETC) and formed cobweb‐like networks. The presence of VETC (VETC+) predicted higher metastasis and recurrence rates of HCC. Using clinical samples and mouse xenograft models, we further showed that VETC was composed of functional vessels with blood perfusion and induced by tumor cells at the early stage of HCC. Subsequent investigations revealed that HCC cell–derived angiopoietin‐2 was a prerequisite for VETC formation and that the VETC pattern was a critical factor promoting HCC metastasis as knockdown of angiopoietin‐2 abolished this vascular pattern and consequently attenuated in vivo tumor metastasis. Interestingly, abrogation of EMT by knockdown of Snail or Slug significantly diminished in vivo metastasis of VETC– xenografts but did not affect that of VETC+ ones, although silencing of Snail or Slug substantially reduced the in vitro migration of both VETC+ and VETC– HCC cells. In contrast to human VETC– cases, EMT signatures were rarely observed in VETC+ cases with metastatic potential. Further analysis revealed that VETC provided an efficient metastasis mode by facilitating the release of whole tumor clusters into the bloodstream. Conclusion: Our findings identify a novel metastasis mechanism that relies on vascular pattern but is independent of EMT, which may provide new targets for antimetastasis therapy and offer a basis for selecting patients who may benefit from certain molecularly targeted drugs. (Hepatology 2015;62:452–465
Although aberrant microRNA (miRNA) expressions have been observed in different types of cancer, their pathophysiologic role and their relevance to tumorigenesis are still largely unknown. In this ...study, we first evaluated the expression of 308 miRNAs in human hepatocellular carcinoma (HCC) and normal hepatic tissues and identified 29 differentially expressed miRNAs in HCC tissues. miR-101, a significantly down-regulated miRNA, was further studied in greater detail because the signal pathway(s) regulated by miR-101 and the role of miR-101 in tumorigenesis have not yet been elucidated. Interestingly, decreased expression of miR-101 was found in all six hepatoma cell lines examined and in as high as 94.1% of HCC tissues, compared with their nontumor counterparts. Furthermore, ectopic expression of miR-101 dramatically suppressed the ability of hepatoma cells to form colonies in vitro and to develop tumors in nude mice. We also found that miR-101 could sensitize hepatoma cell lines to both serum starvation- and chemotherapeutic drug-induced apoptosis. Further investigation revealed that miR-101 significantly repressed the expression of luciferase carrying the 3'-untranslated region of Mcl-1 and reduced the endogenous protein level of Mcl-1, whereas the miR-101 inhibitor obviously up-regulated Mcl-1 expression and inhibited cell apoptosis. Moreover, silencing of Mcl-1 phenocopied the effect of miR-101 and forced expression of Mcl-1 could reverse the proapoptotic effect of miR-101. These results indicate that miR-101 may exert its proapoptotic function via targeting Mcl-1. Taken together, our data suggest an important role of miR-101 in the molecular etiology of cancer and implicate the potential application of miR-101 in cancer therapy.
Summary Background The ability of circulating microRNAs (miRNAs) to detect preclinical hepatocellular carcinoma has not yet been reported. We aimed to identify and assess a serum miRNA combination ...that could detect the presence of clinical and preclinical hepatocellular carcinoma in at-risk patients. Methods We did a three-stage study that included healthy controls, inactive HBsAg carriers, individuals with chronic hepatitis B, individuals with hepatitis B-induced liver cirrhosis, and patients with diagnosed hepatocellular carcinoma from four hospitals in China. We used array analysis and quantitative PCR to identify 19 candidate serum miRNAs that were increased in six patients with hepatocellular carcinoma compared with eight control patients with chronic hepatitis B. Using a training cohort of patients with hepatocellular carcinoma and controls, we built a serum miRNA classifier to detect hepatocellular carcinoma. We then validated the classifiers' ability in two independent cohorts of patients and controls. We also established the classifiers' ability to predict preclinical hepatocellular carcinoma in a nested case-control study with sera prospectively collected from patients with hepatocellular carcinoma before clinical diagnosis and from matched individuals with hepatitis B who did not develop cancer from the same surveillance programme. We used the sensitivity, specificity, and area under the receiver operating characteristic curve (AUC) to evaluate diagnostic performance, and compared the miRNA classifier with α-fetoprotein at a cutoff of 20 ng/mL (AFP20). Findings Between Aug 1, 2009, and Aug 31, 2013, we recruited 257 participants to the training cohort, and 352 and 139 participants to the two independent validation cohorts. In the third validation cohort, 27 patients with hepatocellular carcinoma and 135 matched controls were included in the nested case-control study, which ran from Aug 1, 2009, to Aug 31, 2014. We identified a miRNA classifier (Cmi ) containing seven differentially expressed miRNAs (miR-29a, miR-29c, miR-133a, miR-143, miR-145, miR-192, and miR-505) that could detect hepatocellular carcinoma. Cmi showed higher accuracy than AFP20 to distinguish individuals with hepatocellular carcinoma from controls in the validation cohorts, but not in the training cohort (AUC 0·826 95% CI 0·771–0·880 vs 0·814 0·756–0·872, p=0·72 in the training cohort; 0·817 0·769–0·865 vs 0·709 0·653–0·765, p=0·00076 in validation cohort 1; and 0·884 0·818–0·951 vs 0·796 0·706–0·886, p=0·042 for validation cohort 2). In all four cohorts, Cmi had higher sensitivity (range 70·4–85·7%) than did AFP20 (40·7–69·4%) to detect hepatocellular carcinoma at the time of diagnosis, whereas its specificity (80·0–91·1%) was similar to that of AFP20 (84·9–100%). In the nested case-control study, sensitivity of Cmi to detect hepatocellular carcinoma was 29·6% (eight of 27 cases) 12 months before clinical diagnosis, 48·1% (n=13) 9 months before clinical diagnosis, 48·1% (n=13) 6 months before clinical diagnosis, and 55·6% (n=15) 3 months before clinical diagnosis, whereas sensitivity of AFP20 was only 7·4% (n=2), 11·1% (n=3), 18·5% (n=5), and 22·2% (n=6) at the corresponding timepoints (p=0·036, p=0·0030, p=0·021, p=0·012, respectively). Cmi had a larger AUC than did AFP20 to identify small-size (AUC 0·833 0·782–0·883 vs 0·727 0·664–0·792, p=0·0018) and early-stage (AUC 0·824 0·781–0·868 vs 0·754 0·702–0·806, p=0·015) hepatocellular carcinoma and could also detect α-fetoprotein-negative (AUC 0·825 0·779–0·871) hepatocellular carcinoma. Interpretation Cmi is a potential biomarker for hepatocellular carcinoma, and can identify small-size, early-stage, and α-fetoprotein-negative hepatocellular carcinoma in patients at risk. The miRNA classifier could be valuable to detect preclinical hepatocellular carcinoma, providing patients with a chance of curative resection and longer survival. Funding National Key Basic Research Program, National Science and Technology Major Project, National Natural Science Foundation of China.
Recent clinical studies have suggested that programmed death ligand 1 (PD-L1) expression in a tumour could be a potential biomarker for PD-L1/PD-1 blockade therapies.
To better characterise PD-L1 ...expression in hepatocellular carcinoma (HCC), we analysed its expression patterns in 453 HCC patients by double staining for CD68 and PD-L1 using the Tyramide Signal Amplification Systems combined with immunohistochemistry. We also investigated its correlation with clinical features, prognosis and immune status.
The results showed that PD-L1 expression on tumour cells (TCs) was negatively associated with patients' overall survival (OS; P = 0.001) and relapse-free survival (RFS; P = 0.006); however, PD-L1 expression on macrophages (Mφs) was positively correlated with OS (P = 0.017). Multivariate analysis revealed that PD-L1 expression on TCs and Mφs were both independent prognostic factors for OS (hazard ratio (HR) = 1.168, P = 0.004 for TC-PD-L1; HR = 0.708, P = 0.003 for Mφ-PD-L1). Further studies showed that Mφ-PD-L1
tumours exhibited an activated immune microenvironment, with high levels of CD8
T-cell infiltration and immune-related gene expression.
Our study provided a novel methodology to evaluate PD-L1 expression in the tumour microenvironment, which might help to select patients who would benefit from anti-PD-1/PD-L1 immunotherapies.
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