Stimulation of the center of the lateral reticular nucleus suppresses the swallowing reflex in rats.

Morphological studies have demonstrated that the lateral reticular nucleus (LRt) receives fibers projected from sites that are related to control of the swallowing reflex. Although the LRt may therefore be related to control of the swallowing reflex, the functional role of the LRt in the swallowing reflex remains unknown. The present study examined whether the swallowing reflex is modulated by stimulation of the LRt. These experiments were performed on rats anesthetized by urethane. The swallowing reflex was evoked by repetitive electrical stimulation of the superior laryngeal nerve (SLN) and was identified by electromyographic activities from the mylohyoid muscle. Electrical stimulation was applied to the LRt or glutamate was injected into the LRt. The number of swallows was reduced, and the latency of the onset of the first swallow was increased during electrical stimulation near the middle of the rostrocaudal direction of the LRt. The number of swallows was reduced, and the latency of onset of the first swallow increased after microinjection of glutamate near the rostrocaudal center of the LRt. The present study suggests that the LRt is involved in control of the swallowing reflex.

Swallowing and aspiration during sleep in patients with obstructive sleep apnea versus control individuals.

STUDY OBJECTIVES: There are only a few reports on voluntary swallowing during sleep; therefore, this study aimed to propose a method for observing voluntary swallowing during sleep using polysomnography. The frequency of voluntary swallowing during sleep and the factors related to swallowing and aspiration during sleep were investigated. METHODS: Polysomnography records of 20 control subjects and 60 patients with obstructive sleep apnea (OSA) (mild, moderate, and severe groups; n = 20 each) were collected. Simultaneous increases in the electromyographic potentials of the submental and masseter muscles, termed coactivation, and declining oronasal airflow (SA) were extracted as "swallowing." The cough reflex that occurred during sleep was extracted as "aspiration." The frequency of swallowing events was compared among the different OSA severity groups. Subsequently, a multivariate regression analysis was performed. RESULTS: The average frequency of coactivation with SA in control subjects was 4.1 events/h and that without SA was 1.7 events/h. These frequencies increased with the severity of OSA during non-REM sleep. The distance of the hyoid to the Frankfurt plane was associated with the frequency of coactivation with (ß = 0.298, p = 0.017) as well as without SA (ß = 0.271, p = 0.038). The frequency of coactivation without SA was associated with aspiration (B = 0.192, p = 0.042). CONCLUSIONS: Our data provide new insights into the relationship between swallowing and aspiration during sleep. We found that the longer the distance from the hyoid bone to the Frankfurt plane, the higher the coactivation without SA, which could lead to aspiration during sleep. CLINICAL TRIALS: Retrospective observational study of swallowing during sleep in obstructive sleep apnea patients using polysomnography, https://upload.umin.ac.jp/cgi-open-bin/ctr/ctr_view.cgi?recptno=R000050460, UMIN000044187.

Impact of continuous positive airway pressure therapy for nonalcoholic fatty liver disease in patients with obstructive sleep apnea.

BACKGROUND: Obstructive sleep apnea (OSA) has been suggested as an independent risk factor for nonalcoholic fatty liver disease (NAFLD), and continuous positive airway pressure (CPAP) is the first-line therapy for OSA. AIM: To clarify the efficacy of effective CPAP therapy on NAFLD of OSA patients by serum markers and transient elastography (TE) using FibroScan® (Echosens, Paris, France). METHODS: We prospectively enrolled 123 consecutive patients with OSA who met the indications for CPAP. Liver fibrosis and steatosis were assessed using TE. Before and after 6 mo of CPAP therapy, serum markers and TE were assessed for all patients. The mean usage rate of CPAP therapy for 6 mo was arbitrarily calculated in each patient and expressed as "mean compliance index" (m-CI). RESULTS: In 50 OSA patients with NAFLD, both aspartate aminotransferase (AST) and alanine aminotransferase (ALT) levels were significantly decreased after 6 mo of CPAP therapy. Univariate analysis showed that decreased body weight (BW), decreased body mass index (BMI), decreased AST level, decreased hemoglobin A1c, and high m-CI were significantly related with improved ALT level. In multivariate regression model adjusted for quantities of BW change during 6 mo of CPAP therapy, high m-CI tended to improve ALT level (P = 0.051). All 17 OSA patients with NAFLD, high m-CI and no BMI changes showed significant improvements in AST and ALT levels. Meanwhile, no significant changes in TE data or serum fibrosis markers were seen. CONCLUSION: Some NAFLD could be associated with chronic intermittent hypoxia due to OSA independent of BW changes. In those cases, adequate reoxygenation from effective CPAP therapy may improve NAFLD.

Detection and quantification of human-specific mRNA from hepatocyte-like cells derived from dental pulp using real-time polymerase chain reaction.

OBJECTIVES: We quantified viable hepatocyte-like cells (HLCs) administered via portal or tail veins in the livers and lungs of immunodeficient rats using real-time reverse transcription polymerase chain reaction (RT-PCR) and human glyceraldehyde 3-phosphate dehydrogenase (GAPDH) primers. METHODS: Immunodeficient rats were infused with HLCs via portal or tail veins. mRNA was quantified based on the route of cell administration and the presence of liver injury. RESULTS: Human-specific GAPDH mRNA primers detected 0.1 pg human RNA in 100 ng (1:106) of rat liver RNA. When infused into the portal vein, the quantity of HLC mRNA reduced to 5% 3 h after infusion. Most HLCs were entrapped in the lungs when infused via the tail vein and decreased to approximately 10% 6 h after infusion. A small number of HLCs made it to the liver but disappeared rapidly, regardless of liver injury. 24 h after infusion, viable HLCs were detected only in the lungs of rats with liver injury (P < 0.05). CONCLUSIONS: The quantity of viable human cells in immunodeficient rats was estimated using real-time RT-PCR and primers specific to human mRNA.

Practical Use of Transient Elastography in Screening for Nonalcoholic Steatohepatitis in a Japanese Population.

Background and Aims: Fatty infiltration of liver may induce insulin resistance (IR), and a proportion of patients with nonalcoholic fatty liver disease (NAFLD) is diagnosed with nonalcoholic steatohepatitis. Transient elastography is gaining popularity as a means of non-invasively determining both liver stiffness (fibrosis level) and degree of fatty infiltration, expressed as controlled attenuation parameter (CAP) value. Methods: The aims of this study were to investigate the association between IR and level of fatty liver, and to identify the group at a greater risk of nonalcoholic steatohepatitis using transient elastography and other noninvasive fibrosis markers. A total of 169 patients without chronic hepatitis B and C were analyzed. Results: The CAP value was significantly associated with IR (HOMA-IR ≥2.5; AUROC = 0.81), and the optimal cut-off to discriminate IR was 264 dB/m. The liver stiffness measurement and aspartate aminotransferase-to-platelet ratio index values were significantly higher for CAP ≥264 than in CAP <264. The 9 patients among the overall 169 patients (5.3%) and among the 102 NAFLD patients (8.8%) who showed ≥264 dB and ≥7.0 kPa in transient elastography could represent good candidates for liver biopsy. Conclusions: Evaluation of NAFLD based on CAP values was useful in diagnosing IR. About 9% of NAFLD patients in a Japanese outpatient clinic with a few metabolic complications might be considered good candidates for liver biopsy to confirm nonalcoholic steatohepatitis.

Dental pulp cell bank as a possible future source of individual hepatocytes.

Mesenchymal stem cells (MSCs) as a source for regenerative medicine are now the subject of much clinical attention. There are high expectations due to their safety, low tumorigenic risk, and low ethical concerns. MSC therapy has been approved for acute graft-versus host diseases since 2015. Tooth-derived MSCs are known to have a great potential in their proliferation and differentiation capacities, even when compared with bone-marrow-derived MSCs. In particular, stem cells from human exfoliated deciduous teeth (SHEDs) are the best candidates for personal cell banking (dental pulp cell bank), because they can be obtained less invasively in the natural process of individual growth. SHEDs are known to differentiate into hepatocytes. There have been several studies showing the effectiveness of SHEDs on the treatment of liver failure in animal models. They may exert their effects either by repopulation of cells in injured liver or by paracrine mechanisms due to their immune-regulatory functions. Moreover, it may be possible to use each individuals' dental pulp cells as a future source of tailor-made differentiated hepatocytes in the context of a bioartificial liver or liver-on-a-chip to screen for drug toxicity.

A Case of Right-Sided Ulcerative Colitis with Mesalamine-Induced Hypersensitivity Reactions.

BACKGROUND Ulcerative colitis (UC) is a chronic inflammatory bowel disease, affecting the colon continuously from the rectum proximally. However, a clinical type with right-sided colitis sparing the anal side of the colon is also known. Mesalamine, which is generally used to treat UC, can rarely aggravate the disease. CASE REPORT A 56-year-old woman with no history of colonic diseases visited our hospital because of a positive fecal occult blood test. The first colonoscopy showed inflamed and edematous mucosa extending from the ascending colon to the right-half of the transverse colon. Colonic biopsy specimens demonstrated infiltrations of chronic inflammatory cells in the mucosa and crypt abscesses, but no epithelioid granulomas, compatible with UC. She was highly positive for PR3-ANCA, confirming the diagnosis of UC. After starting mesalamine, she had hypersensitivity reactions and aggravations of UC, which were confirmed endoscopically. CONCLUSIONS Right-sided colitis may be a subgroup of UC, and this is the first report of this type of disease complicated by aggravation due to mesalamine hypersensitivity.

Efficacy and safety of telaprevir- and simeprevir-based triple therapies for older patients with chronic hepatitis C.

AIM: To evaluate and compare the efficacy and safety of telaprevir (TVR)-and simeprevir (SMV)-based triple therapies in elderly patients, specifically patients aged 66 years or older. METHODS: The present study enrolled 112 and 76 Japanese patients with chronic hepatitis C virus genotype 1b infection who were treated with a 12-wk TVR-based or SMV-based triple therapy, respectively, followed by a dual therapy that included pegylated interferon α and ribavirin (RBV) for 12 wk. The patients were categorized into two groups according to age as follows: A younger group of patients aged ≤ 65 years old and an older group of patients aged > 65 years old. Among the patients treated with TVR-based triple therapy, 34 patients were included in the older group. The median ages were 56 years (range: 28-65 years) in the younger group and 69 years (range: 66-81 years) in the older group. Among the patients treated with SMV-based triple therapy, 39 patients were included in the older group. The median ages were 59 years (range: 36-65 years) in the younger group and 71 years (range: 66-86 years) in the older group. The clinical, biochemical and virological data were analyzed before and during treatment. RESULTS: Among the patients treated with the TVR-based triple therapy, no significant difference in the sustained virological response (SVR) was found between the younger (80.8%) and older (88.2%) groups. The SVR rates for patients with the interleukin 28B (IL28B) (rs8099917) TG/GG-genotypes (73.9% and 60.0% in the younger and older groups, respectively) were significantly lower than for patients with the IL28B TT-genotype (86.3% and 92.9%, respectively). The cumulative exposure to RBV for the entire 24-wk treatment period (as a percentage of the target dose) was significantly higher in the younger group than in the older group (91.7% vs 66.7%, respectively, P < 0.01), but the cumulative exposure to TVR was not significantly different between the younger and older groups (91.6% vs 81.9%, respectively). A multivariate analysis identified the TT-genotype of IL28B (OR = 8.160; 95%CI: 1.593-41.804, P = 0.012) and the adherence of RBV (> 60%) (OR = 11.052; 95%CI: 1.160-105.273, P = 0.037) as independent factors associated with the SVR. Adverse events resulted in discontinuation of the treatment in 11.3% and 14.7% of the younger and older groups, respectively. Among the patients treated with the SMV-based triple therapy, no significant difference in the SVR rare was found between the younger (81.1%) and older (82.1%) groups. The SVR rates for patients with the IL28B TG/GG-genotypes (77.8% and 64.7% in the younger and older groups, respectively) were significantly lower than for patients with the IL28B TT-genotype (88.2% and 100%, respectively). A multivariate analysis identified the TT-genotype of IL28B as an independent factor associated with the SVR (OR = 9.677; 95%CI: 1.114-84.087, P = 0.040). Adverse events resulted in discontinuation of the treatment in 7.0% and 14.3% of patients in the younger and older groups, respectively. CONCLUSION: Both TVR- and SMV-based triple therapies can be successfully used to treat patients aged 66 years or older with genotype 1b chronic hepatitis C. Genotyping of the IL28B indicates a potential to achieve SVR in these difficult-to-treat elderly patients.

Regenerative medicine using dental pulp stem cells for liver diseases.

Acute liver failure is a refractory disease and its prognosis, if not treated using liver transplantation, is extremely poor. It is a good candidate for regenerative medicine, where stem cell-based therapies play a central role. Mesenchymal stem cells (MSCs) are known to differentiate into multiple cell lineages including hepatocytes. Autologous cell transplant without any foreign gene induction is feasible using MSCs, thereby avoiding possible risks of tumorigenesis and immune rejection. Dental pulp also contains an MSC population that differentiates into hepatocytes. A point worthy of special mention is that dental pulp can be obtained from deciduous teeth during childhood and can be subsequently harvested when necessary after deposition in a tooth bank. MSCs have not only a regenerative capacity but also act in an anti-inflammatory manner via paracrine mechanisms. Promising efficacies and difficulties with the use of MSC derived from teeth are summarized in this review.

Natural regression of fibrosis in chronic hepatitis B.

The fibrosis of liver cirrhosis was considered to be irreversible before the anti-viral drugs showed that it is reversible when they lead to continuous suppression of viral replication and inflammation. However, several reports previously showed that fibrosis of type B liver cirrhosis was almost completely absorbed after the natural remission of chronic inflammation. This phenomenon might not be limited to exceptional patients, but rather occur commonly, considering the dynamic clinical features of chronic hepatitis B (CHB), where inactive carrier stage normally follows aggravation of hepatitis and progression of fibrosis at the time of HBeAg seroconversion. Thus, fibrosis levels of CHB as a hepatocellular carcinoma (HCC)-surveillance marker, particularly those of the inactive stage, could be underestimated, because some of them might have been (pre)cirrhotic in the past and recovered with the natural regression of fibrosis. We argue that cirrhosis-induced HCC mechanisms, rather than direct action of viral genome, may be more common than generally considered in CHB patients. This may have some impact on reconsidering the surveillance rationale for HCC in CHB, from where advanced HCCs tended to be missed. In addition, a molecular marker to assess the cancer-prone characteristics of the liver will definitely be needed to resolve the issue.

Characteristics of colorectal tumours in asymptomatic patients with negative immunochemical faecal occult blood test results.

The immunochemical faecal occult blood test (iFOBT) is a simple, non-invasive colorectal cancer (CRC) screening method for reducing CRC-related mortality. However, the sensitivity of iFOBT is imperfect and certain colonic neoplasms that require removal may be missed. The aim of this study was to investigate the incidence and characteristics of CRC in asymptomatic, iFOBT-negative patients who underwent opportunistic screening. A total of 919 subclinical patients (276 iFOBT-positive and 643 iFOBT-negative) in the health screening program of our hospital underwent total colonoscopy (TCS) within 2 years after iFOBT. The patients were divided into an iFOBT-positive and an iFOBT-negative group and the TCS findings were compared between the two groups. Although the incidence of advanced neoplasia (CRC, high-grade dysplasia, adenoma sized ≥10 mm and tubulovillous adenoma) was significantly higher in the iFOBT-positive group, these lesions were also found in 6.3% of iFOBT-negative patients. The lesions tended to be proximally located and non-protruding. In conclusion, screening with iFOBT remains clinically significant. However, colonoscopy is indispensable for reducing the incidence and mortality of CRC.

Contributions of transgenic mouse studies on the research of hepatitis B virus and hepatitis C virus-induced hepatocarcinogenesis.

Transgenic mouse technology has enabled the investigation of the pathogenic effects, including those on development, immunological reactions and carcinogenesis, of viral genes directly in living organism in a real-time manner. Although viral hepatocarcinogenesis comprises multiple sequences of pathological events, that is, chronic necroinflammation and the subsequent regeneration of hepatocytes that induces the accumulation of genetic alterations and hepatocellular carcinoma (HCC), the direct action of viral proteins also play significant roles. The pathogenesis of hepatitis B virus X and hepatitis C virus (HCV) core genes has been extensively studied by virtue of their functions as a transactivator and a steatosis inducer, respectively. In particular, the mechanism of steatosis in HCV infection and its possible association with HCC has been well studied using HCV core gene transgenic mouse models. Although transgenic mouse models have remarkable advantages, they are intrinsically accompanied by some drawbacks when used to study human diseases. Therefore, the results obtained from transgenic mouse studies should be carefully interpreted in the context of whether or not they are well associated with human pathogenesis.

Direct antiviral agent treatment of decompensated hepatitis C virus-induced liver cirrhosis.

Recently, direct antiviral agents (DAAs) have been increasingly used for the treatment of chronic hepatitis C virus (HCV) infections, replacing interferon-based regimens that have severe adverse effects and low tolerability. The constant supply of new DAAs makes shorter treatment periods with enhanced safety possible. The efficacy of DAAs for treatment of compensated liver cirrhosis (LC) is not less than that for treatment of non-cirrhotic conditions. These clinical advantages have been useful in pre- and post-liver transplantation (LT) settings. Moreover, DAAs can be used to treat decompensated HCV-induced LC in elderly patients or those with severe complications otherwise having poor prognosis. Although encouraging clinical data are beginning to appear, the actual efficacy of DAAs for suppressing disease progression, allowing delisting for LT and, most importantly, improving prognosis of patients with decompensated HCV-LC remains unknown. Case-control studies to examine the short- or long-term effects of DAAs for treatment of decompensated HCV-LC are urgently need.

Oncogenic role of p21 in hepatocarcinogenesis suggests a new treatment strategy.

A well-known tumor suppressor, p21, acts paradoxically by promoting tumor growth in some cellular conditions. These conflicting functions have been demonstrated in association with the HBx gene and in hepatocarcinogenesis. The molecular behavior of p21 depends on its subcellular localization. Nuclear p21 may inhibit cell proliferation and be proapoptotic, while cytoplasmic p21 may have oncogenic and anti-apoptotic functions. Because most typical tumor suppressive proteins also have different effects according to subcellular localization, elucidating the regulatory mechanisms underlying nucleo-cytoplasmic transport of these proteins would be significant and may lead to a new strategy for anti-hepatocellular carcinoma (HCC) therapy. Chromosome region maintenance 1 (CRM1) is a major nuclear export receptor involved in transport of tumor suppressors from nucleus to cytoplasm. Expression of CRM1 is enhanced in a variety of malignancies and in vitro studies have shown the efficacy of specific inhibition of CRM1 against cancer cell lines. Interestingly, interferon may keep p21 in the nucleus; this is one of the mechanisms of its anti-hepatocarcinogenic function. Here we review the oncogenic property of p21, which depends on its subcellular localization, and discuss the rationale underlying a new strategy for HCC treatment and prevention.

Hepatitis B virus X stimulates redox signaling through activation of ataxia telangiectasia mutated kinase.

Hepatitis B virus X (HBX) protein plays a crucial role in carcinogenesis, but its mechanism is unclear. The involvement of ataxia telangiectasia mutated (ATM) kinase in the enhanced redox system was investigated by examining the phosphorylation level of ATM in HBX gene-transfected cells and in transgenic mice following redox system manipulation by treatment with hydrogen peroxide (H2O2) or antioxidant. Western blotting and immunostaining showed that phospho-ATM was significantly increased by HBX both in vitro (3.2-fold; p<0.05) and in vivo (4-fold; p<0.05), and this effect was abrogated by antioxidant treatment. The level of PKC-δ in HBX-expressing cells was increased 3.5-fold compared to controls. Nuclear localized NF-E2-related factor 2 (Nrf2) was increased in HBX-expressing cells exposed to H2O2, but remained at lower levels after the treatment with rottlerin, KU55933, or caffeine. The levels of anti-oxidant molecules were increased in HBX expressing cells and in transgenic mice, indicating that HBX stimulates the Nrf2-mediated redox system. The levels of intracellular reactive oxygen species (ROS) were significantly increased in HBX-expressing cells treated with hydrogen peroxide in the presence of ATM inhibitor KU55933 or caffeine. Treatment of HBX-expressing cells with KU55933 or caffeine before the exposure to H2O2 increased the ratio of cell apoptosis to 33±4% (p<0.05) and 22±4% (p<0.05), respectively. Collectively, HBX stimulates the ATM-mediated PKC-δ/Nrf2 pathway, and maintains the enhanced activity of the redox system. Therefore, manipulating ATM kinase activity might be a useful strategy for treating HBX-induced carcinogenesis.

Double staining with crystal violet and methylene blue is appropriate for colonic endocytoscopy: an in vivo prospective pilot study.

BACKGROUND AND AIM: Endocytoscopy (EC) at ultra-high magnification enables in vivo visualization of cellular atypia of gastrointestinal mucosae. Clear images are essential for precise diagnosis by EC. The aim of the present study was to evaluate the optimal staining method for EC in the colon. METHODS: Thirty prospectively enrolled patients were allocated 1:1:1 to three distinct staining methods: 0.05% crystal violet (CV) alone, 1% methylene blue (MB) alone, or CV+MB (CM double). Normal rectal mucosae were stained with each dye and videos of EC images were recorded. Visibility of nuclei and gland formation after staining were evaluated as 'recognizable' or 'not recognizable'. Time for each parameter to become 'recognizable' was measured, and the average times for the three staining regimens were compared. RESULTS: MB alone and CM double staining resulted in 'recognizable' (102 ± 27 vs 89 ± 22 s, P=0.263) nuclei within comparable periods of time, whereas CV alone was unable to identify nuclei. Gland formation became 'recognizable' sooner after CM double staining than after MB alone (61 ± 16 vs 108 ± 24 s, P<0.001). CONCLUSIONS: Double staining with CV and MB, which rapidly provided recognizable images of both nuclei and gland formation, is an appropriate staining regimen for colonic EC.

Hepatitis B virus X induces cell proliferation in the hepatocarcinogenesis via up-regulation of cytoplasmic p21 expression.

BACKGROUND: Hepatitis B virus X protein (HBx) has been shown to induce hepatocarcinogenesis by disrupting the functions of intracellular molecules. Cyclin-dependent kinase inhibitor p21 (Cip1/WAF1), known as a tumour-suppressor gene, has been reported to have paradoxical function, that is, acting as an oncogene, particularly when expressed in the cytoplasm. The effects of HBx on the expression and function of p21 also remain controversial. AIMS: We attempted to investigate the role of HBx in the hepatocarcinogenic process, focusing on the association with this paradoxical function of p21. The results obtained were further verified with experiments using the antihepatocarcinogenic action of interferon (IFN)-ß. METHODS: HBx transgenic mice (Xg) and HBx-transfected hepatoma cell lines were used. Intracellular localization of p21 was determined by Western blot analysis and immunofluorescence. RESULTS: Xg and HBx-transfected cells exhibited increased expression of p21. Up-regulation of p21 was positively correlated with the expression of cyclin D1 and inactive phosphorylation of retinoblastoma protein (pRb). These HBx-induced cell proliferative responses were cancelled by knockdown of p21, which resulted in growth reduction in HBx-expressing cells, suggesting the oncogenic properties of HBx-induced p21. HBx induced accumulation of p21 in the cytoplasm, and activation of PKCα was involved. Finally, IFN-ß-treated Xg liver, as well as hepatoma cells, showed a shift of cytoplasmic p21 to the nucleus, accompanied by the abrogation of HBx-induced oncogenic modulation. CONCLUSIONS: Our results suggest that HBx induces hepatocarcinogenesis via PKCα-mediated overexpression of cytoplasmic p21 and IFN-ß suppressed these molecular events by shifting p21 to the nucleus.

Blockade of ataxia telangiectasia mutated sensitizes hepatoma cell lines to sorafenib by interfering with Akt signaling.

Sorafenib is a multi-kinase inhibitor applicable to hepatocellular carcinoma (HCC), but its limited therapeutic effects are a major problem to be solved. Here, we show that blockade of ataxia telangiectasia mutated (ATM) improves the antitumor effects of sorafenib. When hepatoma cell lines HepG2 and PLC/PRF/5 were treated with sorafenib plus ATM small inhibitory RNAs, ATM inhibitor KU55933 or caffeine, Akt signaling was suppressed and the cytotoxic effects were significantly potentiated. Moreover, ATM inhibition effectively suppressed the sorafenib-induced cell migration. Taken together, manipulation of ATM activity might be a useful strategy for improving sorafenib treatment of HCC.

Reduced NKG2D ligand expression in hepatocellular carcinoma correlates with early recurrence.

BACKGROUND & AIMS: The activating receptor natural killer group 2, member D (NKG2D) and its ligands play a crucial role in immune response to tumors. NKG2D ligand expression in tumors has been shown to be associated with tumor eradication and superior patient survival, but the involvement of NKG2D ligands in the immune response against hepatocellular carcinoma (HCC) still remains to be elucidated. METHODS: We investigated the expression of NKG2D ligands in HCC tissues collected from 54 patients and HCC cell lines. We also examined the proteasome expression and the effect of inhibition of proteasome activity on NKG2D ligand expression in HCC tissues and cell lines. RESULTS: In dysplastic nodules (DN), well-differentiated (well-HCC), and moderately-differentiated HCCs (mod-HCC), UL16-binding protein (ULBP) 1 was expressed predominantly in tumor cells, but not in poorly-differentiated HCCs (poor-HCC). Remarkably, recurrence-free survival of patients with ULBP1-negative HCC was significantly shorter than that of patients with ULBP1-positive HCC (p=0.006). Cox regression analysis revealed that loss of ULBP1 expression was an independent predictor of early recurrence (p=0.008). We confirmed that ULBP1 was expressed in the well- and mod-HCC cell lines, but not in the poor-HCC cell line KYN-2. However, inhibition of proteasome activity resulted in significant up-regulation of ULBP1 expression in KYN-2. Moreover, we found that 20S proteasome expression was more abundant in KYN-2 than that in the well- and mod-HCC cell lines. CONCLUSIONS: ULBP1 is prevalently expressed in DN to mod-HCC, but loss of its expression correlates with tumor progression and early recurrence.