Des-γ-carboxyl prothrombin is associated with tumor angiogenesis in hepatocellular carcinoma.

BACKGROUND AND AIM: Hepatocellular carcinoma (HCC) is a hypervascular tumor, and angiogenesis plays an important role in its development. Previously, we demonstrated that des-γ-carboxyl prothrombin (DCP) promotes both cell proliferation and migration of human umbilical vein endothelial cells (HUVECs) by inducing the autophosphorylation of kinase insert domain receptor (KDR). In the present study, DCP-associated tumor angiogenesis was assessed by comparing hypovascular and common hypervascular HCC. METHODS: The solitary HCCs of 827 patients were classified into two groups according to the tumor density at the arterial phase of a dynamic computed tomography scan; the initial clinical data of patients with the hyper- and hypovascular types were compared. The HCC tissues from 95 tumors were analyzed by immunohistochemical staining for DCP and phosphorylated KDR, and intratumoral microvessel density (MVD) was analyzed to evaluate microvessel angiogenesis. RESULTS: The serum DCP levels (320 ± 3532 mAU/mL) and tumor size (18.4 ± 9.0 mm) of patients with hypervascular HCC were significantly greater than those with hypovascular HCC (38.7 ± 80 mAU/mL and 14.6 ± 5.2 mm, P < 0.001). Immunohistochemical analysis revealed that the expressions of DCP and phospho-KDR were significantly greater in hypervascular HCC (71.4% and 31.0%, respectively) than in hypovascular HCC (7.6% and 5.7%, respectively). Intratumoral MVD was significantly correlated with DCP (r = 0.48, P < 0.0001). CONCLUSIONS: des-γ-carboxyl prothrombin production is associated with tumor angiogenesis in HCC.

Restored expression of the tumor suppressor gene RUNX3 reduces cancer stem cells in hepatocellular carcinoma by suppressing Jagged1-Notch signaling.

Runt-related transcription factor 3 (RUNX3) is a candidate tumor suppressor gene that is downregulated in various cancers. In the present study, we analyzed the regulatory function of RUNX3 on Jagged-1 (JAG1) expression and cancer stem cell (CSC) signaling in hepatocellular carcinoma (HCC). Eleven HCC cell lines and 30 human HCC tissues were used. RUNX3 and JAG1 expression levels were analyzed by immunoblotting and immunohistochemistry. Ectopic RUNX3 expression was induced by introducing RUNX3 cDNA into the RUNX3-negative HCC cell line Hep3B and Huh7 cells. Furthermore endogenous RUNX3 expression was knocked down by RUNX3 siRNA in SK-Hep-1 cells. In order to analyze JAG1 transcriptional regulation, we conducted reporter assays, chromatin immunoprecipitation (ChIP) assays and electrophoretic mobility shift assays (EMSAs). Tumorigenicity was analyzed using a SCID mouse liver injection model. An inverse correlation was observed between RUNX3 expression and JAG1 expression in most HCC cell lines and tissues. Restoring RUNX3 expression decreased the expression of JAG1 in Hep3B and Huh7 cells, whereas JAG1 expression was upregulated in RUNX3 siRNA-treated SK-Hep-1 cells. Reporter assays, ChIP assays and EMSAs revealed that RUNX3 directly bound to the transcriptional regulatory region of JAG1 and suppressed JAG1 transcription. Moreover, RUNX3 restoration downregulated CSCs by suppressing JAG1-mediated Notch signaling. The tumorigenic capacity of RUNX3-expressing Hep3B cells was lower compared to that of control Hep3B cells. RUNX3 expression suppressed JAG1 expression and resulted in downregulation of tumorigenesis by suppression of JAG1-mediated CSCs.

Hepatic stellate cells require a stiff environment for myofibroblastic differentiation.

The myofibroblastic differentiation of hepatic stellate cells (HSC) is a critical event in liver fibrosis and is part of the final common pathway to cirrhosis in chronic liver disease from all causes. The molecular mechanisms driving HSC differentiation are not fully understood. Because macroscopic tissue stiffening is a feature of fibrotic disease, we hypothesized that mechanical properties of the underlying matrix are a principal determinant of HSC activation. Primary rat HSC were cultured on inert polyacrylamide supports of variable but precisely defined shear modulus (stiffness) coated with different extracellular matrix proteins or poly-L-lysine. HSC differentiation was determined by cell morphology, immunofluorescence staining, and gene expression. HSC became progressively myofibroblastic as substrate stiffness increased on all coating matrices, including Matrigel. The degree rather than speed of HSC activation correlated with substrate stiffness, with cells cultured on supports of intermediate stiffness adopting stable intermediate phenotypes. Quiescent cells on soft supports were able to undergo myofibroblastic differentiation with exposure to stiff supports. Stiffness-dependent differentiation required adhesion to matrix proteins and the generation of mechanical tension. Transforming growth factor-ß treatment enhanced differentiation on stiff supports, but was not required. HSC differentiate to myofibroblasts in vitro primarily as a function of the physical rather than the chemical properties of the substrate. HSC require a mechanically stiff substrate, with adhesion to matrix proteins and the generation of mechanical tension, to differentiate. These findings suggest that alterations in liver stiffness are a key factor driving the progression of fibrosis.

Loss of runt-related transcription factor 3 expression leads hepatocellular carcinoma cells to escape apoptosis.

BACKGROUND: Runt-related transcription factor 3 (RUNX3) is known as a tumor suppressor gene for gastric cancer and other cancers, this gene may be involved in the development of hepatocellular carcinoma (HCC). METHODS: RUNX3 expression was analyzed by immunoblot and immunohistochemistry in HCC cells and tissues, respectively. Hep3B cells, lacking endogenous RUNX3, were introduced with RUNX3 constructs. Cell proliferation was measured using the MTT assay and apoptosis was evaluated using DAPI staining. Apoptosis signaling was assessed by immunoblot analysis. RESULTS: RUNX3 protein expression was frequently inactivated in the HCC cell lines (91%) and tissues (90%). RUNX3 expression inhibited 90±8% of cell growth at 72 h in serum starved Hep3B cells. Forty-eight hour serum starvation-induced apoptosis and the percentage of apoptotic cells reached 31±4% and 4±1% in RUNX3-expressing Hep3B and control cells, respectively. Apoptotic activity was increased by Bim expression and caspase-3 and caspase-9 activation. CONCLUSION: RUNX3 expression enhanced serum starvation-induced apoptosis in HCC cell lines. RUNX3 is deleted or weakly expressed in HCC, which leads to tumorigenesis by escaping apoptosis.

Twist expression promotes migration and invasion in hepatocellular carcinoma.

BACKGROUND: Twist, a transcription factor of the basic helix-loop-helix class, is reported to regulate cancer metastasis. It is known to induce epithelial-mesenchymal transition (EMT). In this study, we evaluated the expression of twist and its effect on cell migration in hepatocellular carcinoma (HCC). METHODS: We examined twist expression using immunohistochemistry in 20 tissue samples of hepatocellular carcinoma, and assessed twist expression in HCC cell lines by RT-PCR and Western blot analysis. Ectopic twist expression was created by introducing a twist construct in the twist-negative HCC cell lines. Endogenous twist expression was blocked by twist siRNA in the twist-positive HCC cell lines. We studied EMT related markers, E-cadherin, Vimentin, and N-cadherin by Western blot analysis. Cell proliferation was measured by MTT assay, and cell migration was measured by in vitro wound healing assay. We used immunofluorescent vinculin staining to visualize focal adhesion. RESULTS: We detected strong and intermediate twist expression in 7 of 20 tumor samples, and no significant twist expression was found in the tumor-free resection margins. In addition, we detected twist expression in HLE, HLF, and SK-Hep1 cells, but not in PLC/RPF/5, HepG2, and Huh7 cells. Ectopic twist-expressing cells demonstrated enhanced cell motility, but twist expression did not affect cell proliferation. Twist expression induced epithelial-mesenchymal transition together with related morphologic changes. Focal adhesion contact was reduced significantly in ectopic twist-expressing cells. Twist-siRNA-treated HLE, HLF, and SK-Hep1 cells demonstrated a reduction in cell migration by 50, 40 and 18%, respectively. CONCLUSION: Twist induces migratory effect on hepatocellular carcinoma by causing epithelial-mesenchymal transition.

Narrow-band imaging provides reliable screening for esophageal malignancy in patients with head and neck cancers.

OBJECTIVES: The narrow-band imaging (NBI) system is a novel technology that enhances the visualization of microvasculature and mucosal patterns. The aim of this study was to assess the reliability of the NBI system for esophageal cancer screening in patients with head and neck cancers. METHODS: A total of 142 patients with head and neck squamous cell carcinoma (SCC) were examined by NBI endoscopy, followed by Lugol chromoendoscopy between April 2006 and June 2008 at the Okayama University Hospital, Okayama, Japan. Detection of SCC and high-grade intraepithelial neoplasia (HGIN) was conducted. RESULTS: The median age of the patients was 64 years (range: 29-86 years), and approximately three-fourths of all the patients were male. In total, 21 superficial lesions in 16 patients were detected by NBI endoscopy. Of these, 4 lesions were diagnosed histologically as SCC and 11 lesions as HGIN. An additional 22 Lugol-voiding lesions >or=5 mm were detected in 19 patients by Lugol chromoendoscopy. Although 1 of these lesions was diagnosed as HGIN, 21 lesions were diagnosed as low-grade intraepithelial neoplasia or lesions without atypical findings. The sensitivity of NBI endoscopy for detecting esophageal SCC and HGIN was 90.9% (95% confidence interval (CI), 58.7-99.8), specificity was 95.4% (95% CI, 90.3-98.3), and accuracy was 95.1% (95% CI, 90.1-98.0). CONCLUSIONS: NBI seems to be useful and reliable for screening for esophageal SCC in patients with head and neck cancers.

Risk factors associated with local recurrence of early gastric cancers after endoscopic submucosal dissection.

BACKGROUND: Although endoscopic submucosal dissection (ESD) is expected to reduce the local recurrence of gastric cancers, we still experience cases of recurrence after an ESD. OBJECTIVE: To characterize clinical and pathologic features of cases with local recurrence of early gastric cancer after an ESD. DESIGN: A prospective cohort study. SETTING AND PATIENTS: A total of 306 patients with gastric cancers removed by ESD at Okayama University Hospital and Tsuyama Central Hospital between March 2001 and December 2005 were enrolled. INTERVENTION: ESD. MAIN OUTCOME MEASUREMENT: Local recurrence. RESULTS: The incidence of a complete en bloc resection was 80.4% when pathologically evaluated. Within a median follow-up period of 26 months (12-64 months), a local recurrence was found in 7 cases, all of which had been declared incomplete resections. One patient underwent a second ESD, and the remaining 6 underwent a surgical resection. All removed lesions were mucosal cancers. No lymph-node metastases were found in patients with a surgical resection. There was a significant correlation between the incidence of an incomplete resection and that of a local recurrence (P < .0001). Among the clinical characteristics, tumor size (>30 mm vs <20 mm; odds ratio [OR] 16 mm [95% CI, 2.0-130 mm]) and tumor location (upper vs middle or lower; OR 7.6 [95% CI, 1.3-45]) were identified as factors that were significantly associated with the incidence of a local recurrence. LIMITATION: Short follow-up duration. CONCLUSIONS: The incidence of a local recurrence was strongly associated with that of an incomplete resection. The frequency of a local recurrence also showed significant correlations with the tumor size and location within the stomach.

Exon 2 deletion splice variant of gamma-glutamyl carboxylase causes des-gamma-carboxy prothrombin production in hepatocellular carcinoma cell lines.

Using GGCX gene-specific real-time PCR, exon 2 deletion splice variant of vitamin K-dependent gamma-glutamyl carboxylase (GGCX) mRNA was identified in HCC cell lines. Expressions of wild type and exon 2 deletion variant of GGCX were analyzed with relevance to DCP production in HCC cell lines. Hep3B, HepG2, HuH1, HuH7, and PLC/PRF/5 produced DCP, while SK-Hep-1, HLE, HLF, and JHH1 produced no detectable level of DCP. DCP-producing cells expressed exon 2 deletion variant of GGCX mRNA and protein, while DCP-negative cells expressed no detectable level of exon 2 deletion variant of GGCX. These results suggest that exon 2 deletion splice variant of GGCX causes dysfunction of GGCX enzyme activity resulting in DCP production in HCC cell lines.

Increased stiffness of the rat liver precedes matrix deposition: implications for fibrosis.

Liver fibrosis, the response to chronic liver injury, results from the activation of mesenchymal cells to fibrogenic myofibroblasts. We have recently shown that two key myofibroblast precursor populations, hepatic stellate cells and portal fibroblasts, undergo activation in culture in response to increasing substrate stiffness. We therefore hypothesized that alterations in liver stiffness precede myofibroblast activation and fibrosis in vivo as well. To test this hypothesis, we induced fibrosis in rats by twice weekly injections of carbon tetrachloride (CCl(4)) and then killed the animals at various time points ranging from 3 to 70 days after the initiation of injury. The shear storage modulus of the whole liver was measured on fresh tissue; fixed and frozen tissue from the same livers was used to quantify fibrosis. We observed that liver stiffness increased immediately and continued to increase, leveling out by day 28. Fibrosis, measured histologically by trichrome staining as well as by quantitative sirius red staining, increased with time, although these increases were delayed relative to changes in stiffness. There was no direct correlation between stiffness and fibrosis at early or late time points. Treatment of a second cohort of rats with the lysyl oxidase inhibitor, beta-aminopropionitrile (BAPN), partially prevented early increases in liver stiffness. We concluded that increases in liver stiffness precede fibrosis and potentially myofibroblast activation. Liver stiffness appears to result from matrix cross-linking and possibly other unknown variables in addition to matrix quantity. We suggest that increased liver stiffness may play an important role in initiating the early stages of fibrosis.

Transforming growth factor-beta and substrate stiffness regulate portal fibroblast activation in culture.

UNLABELLED: Myofibroblasts derived from portal fibroblasts are important fibrogenic cells in the early stages of biliary fibrosis. In contrast to hepatic stellate cells, portal fibroblasts have not been well studied in vitro, and little is known about their myofibroblastic differentiation. In this article we report the isolation and characterization of rat portal fibroblasts in culture. We demonstrate that primary portal fibroblasts undergo differentiation to alpha-smooth muscle actin-expressing myofibroblasts over 10-14 days. Marker analysis comparing portal fibroblasts to hepatic stellate cells demonstrated that these are distinct populations and that staining with elastin and desmin can differentiate between them. Portal fibroblasts expressed elastin at all stages in culture but never expressed desmin, whereas hepatic stellate cells consistently expressed desmin but never elastin. Immunostaining of rat liver tissue confirmed these results in vivo. Characterization of portal fibroblast differentiation in culture demonstrated that these cells required transforming growth factor-beta (TGF-beta): cells remained quiescent in the presence of a TGF-beta receptor kinase inhibitor, whereas exogenous TGF-beta1 enhanced portal fibroblast alpha-smooth muscle actin expression and stress fiber formation. In contrast, platelet-derived growth factor inhibited myofibroblastic differentiation. Portal fibroblasts were also dependent on mechanical tension for myofibroblastic differentiation, and cells cultured on polyacrylamide supports of variable stiffness demonstrated an increasingly myofibroblastic phenotype as stiffness increased. CONCLUSION: Portal fibroblasts are morphologically and functionally distinct from hepatic stellate cells. Portal fibroblast myofibroblastic differentiation can be modeled in culture and requires both TGF-beta and mechanical tension.

IGFBP-3 expression in hepatocellular carcinoma involves abnormalities in TGF-beta and/or Rb signaling pathways.

Insulin-like growth factor binding protein-3 (IGFBP-3) is a mediator of growth suppression signals and a putative tumor suppressor gene. The growth suppression mechanisms of IGFBP-3 have not been well clarified. We examined the expression of IGFBP-3 transcripts in human hepatocellular carcinoma (HCC) and the relationship between IGFBP-3 expression and the transforming growth factor-beta (TGF-beta) and/or retinoblastoma (Rb) signaling pathways. In situ hybridization revealed IGFBP-3 transcripts in cancer cells in 6 of 57 (10%) HCCs, including moderately and poorly differentiated HCCs with intrahepatic metastasis. In contrast, all lung metastatic nodules of 4 HCCs showed IGFBP-3 transcripts in cancer cells. The cDNA microarray showed that genes for the TGF-beta pathway and Rb were up-regulated in IGFBP-3-expressing HCCs. In 6 HCCs presenting IGFBP-3, immunohistochemical analyses showed abnormalities in the TGF-beta and/or Rb pathways; the loss of phosphorylated-Smad2 was observed in 2, and overexpression of phosphorylated-Rb was observed in the remaining 4 HCCs. The present study suggests that IGFBP-3 mediates growth suppression signals via the TGF-beta and/or Rb pathways in HCC.

Smad2 and Smad3 play different roles in rat hepatic stellate cell function and alpha-smooth muscle actin organization.

Hepatic stellate cells (HSC) play a central role in the pathogenesis of liver fibrosis, transdifferentiating in chronic liver disease from "quiescent" HSC to fibrogenic myofibroblasts. Transforming growth factor-beta (TGF-beta), acting both directly and indirectly, is a critical mediator of this process. To characterize the function of the TGF-beta signaling intermediates Smad2 and Smad3 in HSC, we infected primary rat HSC in culture with adenoviruses expressing wild-type and dominant negative Smads 2 and 3. Smad3-overexpressing cells exhibited increased deposition of fibronectin and type 1 collagen, increased chemotaxis, and decreased proliferation compared with uninfected cells and those infected with Smad2 or either dominant negative, demonstrating different biological functions for the two Smads. Additionally, coinfection experiments suggested that Smad2 and Smad3 signal via independent pathways. Smad3-overexpressing cells as well as TGF-beta-treated cells demonstrated more focal adhesions and increased alpha-smooth muscle actin (alpha-SMA) organization in stress fibers, although all cells reached the same level of alpha-SMA expression, indicating that Smad3 also regulates cytoskeletal organization in HSC. We suggest that TGF-beta, signaling via Smad3, plays an important role in the morphological and functional maturation of hepatic myofibroblasts.

Decreased expression of B7 costimulatory molecules and major histocompatibility complex class-I in human hepatocellular carcinoma.

BACKGROUND AND AIM: We analyzed the expression of antigen-processing and antigen-presenting molecules in surgically resected fresh samples of human hepatocellular carcinoma (HCC) tissue to elucidate a mechanism of immune escape. We also examined the expression of interleukin (IL)-10 protein, which might act to downregulate expression of antigen-processing and antigen-presenting molecules. METHODS: Twenty-eight HCC samples obtained by surgical resection were analyzed for the expression of beta2-microglobulin, heat-shock protein (HSP)-70, human leukocyte antigen (HLA) class-I, CD80 (B7-1), CD86 (B7-2) and IL-10 by immunostaining. RESULTS: Beta2-microglobulin and HSP-70 were preserved in all samples. In contrast, the expression of HLA class-I molecules was significantly reduced according to lowering in the histological grading of tumor differentiation (P = 0.024). Furthermore, B7-1 and B7-2 expression was reduced in tumor cells compared with corresponding areas of liver tissue without malignant involvement irrespective of the histological grading of tumors (21% and 36%, respectively). Although IL-10 protein was expressed in 54% of HCC, no relationship between the expression of IL-10 and downregulation of B7-1, B7-2, and HLA class-I was evident. CONCLUSION: These findings suggest the potential role of B7 co-stimulatory molecules and HLA class-I molecules in facilitating HCC escape from immune surveillance without the involvement of IL-10.

Cellular distribution of telomerase reverse transcriptase in human hepatocellular carcinoma.

BACKGROUND AND AIM: Telomerase is the enzyme that synthesizes telomeric DNA, and the activation of telomerase is closely related to cellular immortality. Telomerase activity has been reported in many human cancer tissues and is regulated by the expression of human telomerase reverse transcriptase (hTERT). The aim of the present study was to identify hTERT-expressing cells in human liver tissues and evaluate the feasibility of the hTERT promoter for gene therapy of hepatocellular carcinoma (HCC). METHODS: The authors examined the cellular distribution of hTERT transcripts in surgically resected HCC by in situ hybridization. RESULTS: Among 20 samples, hTERT expression was observed in 15 HCC. Transcripts of hTERT were homogenously distributed in the cytoplasm of HCC cells in nine of 15 cases; six of 15 cases displayed a heterogeneous staining pattern. All poorly differentiated HCC that expressed hTERT showed a homogenous pattern of staining. None of the non-cancerous hepatocytes were positive for the transcripts, but infiltrating lymphocytes were faintly stained. The homogenous expression of hTERT was also observed in the vascular invasion of HCC. CONCLUSIONS: The results indicate that most HCC cells express hTERT RNA and that the promoter is a good candidate as a target for gene therapy. However, careful consideration must be taken concerning the potential effects on lymphocytes.

Identification of the antigens predominantly reacted with serum from patients with hepatocellular carcinoma.

BACKGROUND: To identify antigens specifically recognized by the immune surveillance system in patients with hepatocellular carcinoma (HCC), the authors examined two complementary DNA (cDNA) libraries of moderately differentiated HCC by serologic analysis of recombinant cDNA expression libraries (SEREX). METHODS: The libraries were screened with autologous patients' sera, and sequences of the reacted clones were determined. To study the immunoreactivity of the antigens, sera from 20 patients with HCC, from 20 healthy volunteers, and from 16 patients with chronic viral hepatitis were examined. RESULTS: Twenty-seven antigens were identified. They included SART1, p57Kip2, ROCK-1, gamma-catenin, and heat shock proteins, which are classified as tumor-associated genes. Three of 27 antigens-Tat-binding protein-1 (TBP-1), beta4 integrin-binding protein (p27[BBP]), and ribosomal protein L30 (rpL30)-were reacted predominantly with sera from patients with HCC (55% of patients, 45% of patients, and 20% of patients, respectively). Patients in the control group had no antibodies against these three antigens. Seventy percent of patients with HCC had the antibody against at least one of these antigens. CONCLUSIONS: Disease specific humoral immune response against TBP-1, p27(BBP), and rpL30 was induced in patients with HCC, and the antibodies against these antigens also may be used as tumor markers.

Reduced expression of insulin-like growth factor binding protein-3 and its promoter hypermethylation in human hepatocellular carcinoma.

Insulin-like growth factor binding protein-3 (IGFBP-3) is postulated to be a mediator of growth suppression signals. Reduced expression of the IGFBP-3 was observed in nine out of 12 human hepatocellular carcinomas (HCC) (75%). Promoter hypermethylation of the IGFBP-3 was detected in four out of 12 HCCs (33%) although mutations were not identified. The expression of IGFBP-3 was restored by the demethylating agent 5-aza-2'-deoxycytidine in HCC cell line with promoter hypermethylation (HepG2). As IGFBP-3 functions like a tumor suppressor gene, it may be used as a therapeutic target for HCC.