Vitamin K analog (compound 5) induces apoptosis in human hepatocellular carcinoma independent of the caspase pathway.

A systemic vitamin K analog, compound 5 (Cpd 5), possesses the ability to inhibit cell growth of tumor cells. Therefore, we investigated the effect of Cpd 5 in human hepatocellular carcinoma (HCC) cell lines and evaluated its role in apoptosis. Human HCC cell lines were cultured and treated with Cpd 5. Apoptosis was assessed using DAPI staining and Annexin-V membrane staining. The expression of caspases, XIAP and Bcl-xL was also investigated. Cpd 5 decreased cell viability in a dose-dependent manner in two HCC cells (HLE and SK-Hep1) containing mutant p53, but not in the HepG2 cell line, which contained wild-type p53. Cpd 5-treated HLE and SK-Hep1 cells showed typical apoptotic features, nuclear condensation and nuclear fragmentation upon DAPI staining. Positive membranous staining for Annexin-V was also seen in these cells. Both caspase-8 and caspase-3 activities were up-regulated slightly. Pro-caspase-8 protein levels decreased slightly in both cells. Although the expression of Bcl-xL was not influenced by Cpd 5, that of XIAP decreased in HLE cells. However, the pan-caspase inhibitor, zVAD, could not significantly prevent Cpd 5-induced apoptosis and Cpd 5 could not augment TRAIL-induced apoptosis. These results demonstrate that Cpd 5 induced apoptosis in human HCC cell lines, mainly independently of caspase activities. This may contribute to its highly potent cytotoxicity toward HCC cells.

Functional expression of a proliferation-related ligand in hepatocellular carcinoma and its implications for neovascularization.

AIM: To detect the expression of a proliferation-related ligand on human hepatocellular carcinoma (HCC) cell lines (SK-Hep1, HLE and HepG2) and in culture medium. METHODS: APRIL expression was analyzed by Western blotting in HCC cell lines. Effects of APRIL to cell count and angiogenesis were analyzed, too. RESULTS: Recombinant human APRIL (rhAPRIL) increased cell viability of HepG2 cells and, in HUVEC, rhAPRIL provided slight tolerance to cell death from serum starvation. Soluble APRIL (sAPRIL) from HLE cells increased after serum starvation, but did not change in SK-Hep1 or HepG2 cells. These cells showed down-regulation of VEGF after incubation with anti-APRIL antibody. Furthermore, culture medium from the HCC cells treated with anti-APRIL antibody treatment inhibited tube formation of HUVECs. CONCLUSION: Functional expression of APRIL might contribute to neovascularization via an upregulation of VEGF in HCC.

Expression of TNF-related apoptosis-inducing ligand in human hepatocellular carcinoma.

TNF-related apoptosis-inducing ligand (TRAIL), as well as Fas ligand, plays a pivotal role in lymphocyte cytotoxicity and the maintenance of immunological homeostasis in various tissues, but its physiological role in immune evasion of cancer cells remains unknown. We have previously shown strong resistance to TRAIL-induced cytotoxicity in human hepatocellular carcinomas (HCCs). The current study investigates the expression of TRAIL in HCCs. We found that three HCC cells, HepG2, Hep3B and Huh7 cells, constitutively express TRAIL mRNA and protein, as detected by reverse transcriptase PCR and Western blotting. Four of 10 human HCC tissues demonstrated positive staining for TRAIL, whereas non-tumor tissues showed little detectable staining. TRAIL expression on tumor cells was detected by flow cytometry and was dramatically induced after the addition of doxorubicin, a chemotherapeutic agent, or cytokine stimulation with TNF-alpha, IL-1beta or IL-18. This expression was induced principally via the NF-kappaB activation pathway, since IkappaB transfection significantly reduced TRAIL expression. In addition, the expressed TRAIL was functional. The TRAIL on HCC cells induced apoptosis in Jurkat cells that are sensitive to TRAIL-mediated apoptosis, and this process was specifically inhibited by recombinant TRAIL-receptors:Fc which binds to TRAIL. In conclusion, TRAIL expressed on the surface of HCC cells by cytokines or cytostatic drugs might contribute to an alternative mechanism that enables tumors to evade immune surveillance by inducing apoptosis of activated human lymphocytes.

Augmentation of tumor necrosis factor family-induced apoptosis by E3330 in human hepatocellular carcinoma cell lines via inhibition of NF kappa B.

AIM: To investigate the reduction of cell viability in human hepatocellular carcinoma (HCC) cell lines induced by inhibition of nuclear factor kappa B (NF kappa B). METHODS: HLE, SKHep1, and HepG2 were incubated and E3330 was used to compare the stimulation of some chemotherapeutic drugs with that of TNF family, Fas ligand, TNF alpha and TNF-related apoptosis-inducing ligand (TRAIL) at the point of the reduction of cell viability by inhibiting NF kappa B. RESULTS: E3330 decreased NF kappa B levels in HLE cells stimulated by TNF and TRAIL. The cytotoxicity of the combination of TRAIL, TNF alpha, Fas ligand, and E3330 increased synergistically in a dose-dependent manner compared to either E3330 alone in all HCC cell lines by MTT assay. However, the combination of some chemotherapeutic drugs and E3330 did not decrease the cell viability. CONCLUSION: Inhibition of NF kappa B sensitizes human HCC cell lines to TNF-mediated apoptosis including TRAIL, and TRAIL-based tumor therapy might be a powerful potential therapeutic tool in the treatment of human HCC.

Functional expression of TWEAK in human colonic adenocarcinoma cells.

The TNF-like weak inducer of apoptosis (TWEAK) can induce diverse cellular responses, including cell death, inflammation, migration, and proliferation in various transformed cell lines. We investigated TWEAK sensitivity, TWEAK effects on nuclear factor-kappaB activation, and expression of TWEAK in the HT-29, LS180, SK-CO-1 and SW480 human colonic adenocarcinoma cell lines, all of which express the TWEAK receptor (Fn14). TWEAK alone induced cell death in SW480 cells and induced cell death of HT-29 cells after addition of IFN-gamma, actinomycin D or cycloheximide. TWEAK did not affect cell viability of LS-180 or SK-CO-1 cells. Activation of NF-kappaB was not obviously influenced by TWEAK in any of the cell lines. All four human colonic adenocarcinoma cell lines constitutively expressed TWEAK mRNA, protein and membrane-bound TWEAK antigen, as detected by RT-PCR, Western blotting and flow cytometry. Stimulation by an anticancer drug (camptothecin) augmented cell surface expression of TWEAK and all human colonic adenocarcinoma tissue samples studied (n=59) demonstrated positive staining for TWEAK antigen. Soluble TWEAK was detected in culture medium of these cell lines by ELISA and conditioned medium from SW480 cells incubated with anti-TWEAK antibody significantly inhibited endothelial cell tube formation in Matrigels. Thus, functional expression of TWEAK from human colonic adenocarcinoma cells may contribute to neovascularization.

Adenoviral-mediated transfer of p53 gene enhances TRAIL-induced apoptosis in human hepatocellular carcinoma cells.

p53 is a tumor suppressor protein with numerous biological functions including transformation, regulation of cell growth, differentiation and apoptosis. The TNF-related apoptosis-inducing ligand (TRAIL) can induce apoptosis in various transformed cell lines. We investigated the effects of combining wild-type p53 gene transduction by adenoviral infection (Ad-p53) with addition of TRAIL on cell death, expression levels of TRAIL receptors (TRAIL-R1, TRAIL-R2), FLICE inhibitory protein (FLIP) and X-linked inhibitor of apoptosis protein (XIAP) on human hepatocellular carcinoma (HCC) cell lines. HCC cell death was increased by combination of Ad-p53 infection and addition of TRAIL compared to either alone. Western blotting demonstrated decreased TRAIL-R1 and TRAIL-R2 levels after infection with Ad-p53. FLIP levels decreased in Huh7 cells and Hep3B cells, and XIAP levels decreased in all three HCC cell lines after infection with Ad-p53. Thus, death of HCC cells due to combined p53 gene transduction and exogenous TRAIL may be due to down regulation of FLIP or XIAP.

Functional expression of TWEAK in human hepatocellular carcinoma: possible implication in cell proliferation and tumor angiogenesis.

TNF-like weak inducer of apoptosis (TWEAK) is a member of the TNF family whose transcripts are expressed in various human tissues. Since TWEAK has a variety of biological activities, we investigated TWEAK sensitivity, expression, and physiological role in human hepatocellular carcinomas (HCCs). Tweak receptor was detected in four kinds of HCC cells. TWEAK significantly promoted cell proliferation and induced nuclear factor-kappaB activation in all HCC cells. Surprisingly, we found that HCC cells constitutively express TWEAK. In addition, soluble TWEAK was detected in culture medium. We found that TWEAK also promotes cell proliferation and induces the secretion of IL-8 and MCP-1 in human umbilical vein endothelial cell. Finally, culture medium from Sh-Hep1 cells incubated with anti-TWEAK antibody significantly inhibited endothelial cell tube formation. In conclusion, these results indicate that TWEAK might play a critical role in HCC cellular proliferation using both autocrine and paracrine mechanisms, and modulate tumor-related angiogenesis.

15-deoxy-delta-12-14-PGJ2 regulates apoptosis induction and nuclear factor-kappaB activation via a peroxisome proliferator-activated receptor-gamma-independent mechanism in hepatocellular carcinoma.

The peroxisome proliferator-activated receptor-gamma (PPARgamma) high-affinity ligand, 15-deoxy-Delta-12,14-PGJ(2) (15d-PGJ(2)), is toxic to malignant cells through cell cycle arrest and apoptosis induction. In this study, we investigated the effects of 15d-PGJ(2) on apoptosis induction and expression of apoptosis-related proteins in hepatocellular carcinoma (HCC) cells. 15d-PGJ(2) induced apoptosis in SK-Hep1 and HepG2 cells at a 50 micro M concentration. Pretreatment with the pan-caspase inhibitor, benzyloxycarbonyl-Val-Ala-Asp (OMe) fluoromethyl ketone (2-VAD-fmk), only partially blocked apoptosis induced by 40 micro M 15d-PGJ(2). This indicated that 15d-PGJ(2) induction of apoptosis was associated with a caspase-3-independent pathway. 15d-PGJ(2) also induced down-regulation of the X chromosome-linked inhibitor of apoptosis (XIAP), Bclx, and apoptotic protease-activating factor-1 in SK-Hep1 cells but not in HepG2 cells. However, 15d-PGJ(2) sensitized both HCC cell lines to TNF-related apoptosis-induced ligand-induced apoptosis. In SK-Hep1 cells, cell toxicity, nuclear factor-kappaB (NF-kappaB) suppression, and XIAP down-regulation were induced by 15d-PGJ(2) treatment under conditions in which PPARgamma was down-regulated. These results suggest that the effect of 15d-PGJ(2) was through a PPARgamma-independent mechanism. Although cell toxicity was induced when PPARgamma was down-regulated in HepG2 cells, NF-kappaB suppression and XIAP down-regulation were not induced. In conclusion, 15d-PGJ(2) induces apoptosis of HCC cell lines via caspase-dependent and -independent pathways. In SK-Hep1 cells, the ability of 15d-PGJ(2) to induce cell toxicity, NF-kappaB suppression, or XIAP down-regulation seemed to occur via a PPARgamma-independent mechanism, but in HepG2 cells, NF-kappaB suppression by 15d-PGJ(2) was dependent on PPARgamma.

A new prognostic scoring system involving des-gamma-carboxy prothrombin as a useful marker for predicting prognosis in patients with hepatocellular carcinoma.

A staging system for hepatocellular carcinoma was reported from Italy (CLIP). In this study, we evaluate the CLIP scoring system and establish a new scoring system for predicting the prognosis of patients with hepatocellular carcinoma. Patients (n=141) who were diagnosed and who underwent initial treatment at our single institution were recruited retrospectively into this study. We evaluated markers for prognosis, using a stratified Cox proportional hazard regression model and Kaplan-Meier survival analysis. CLIP score differentiated patients with different survival experiences by Kaplan-Meier estimated survival analysis. However, with respect the CLIP score, more than two thirds of patients were included in the early stage (CLIP 0-1), and the group with better prognosis than the survival rate of all patients was the only one with CLIP 0. Multivariate analysis revealed that des-gamma-carboxy prothrombin (DCP) >/=100 mAU/ml (relative risk, 2.06; P=0.0218) was statistically significant as a predictor of poor survival. A new prognostic scoring system included DCP classified patients to 6 well-balanced groups (score 0-5). The new prognostic scoring system 0 group (14.9% of the cohort) and the CLIP score 0 group (34.0% of the cohort) had a median survival of 66.9 and 61.6 months. The new prognostic scoring system performs better for prediction of survival than either the CLIP score or the Child-Pugh stage. In conclusion, the described scoring system provides more accurate prognostic information than the CLIP scoring system. It may help physicians decide more appropriate clinical and therapeutic management.

Fas stimulation activates NF-kappaB in SK-Hep1 hepatocellular carcinoma cells.

The TNF-receptor family has a dual signaling pathway, including induction of apoptosis and NF-kappaB activation associated with cell survival. Hepatocellular carcinoma (HCC) cells express TNF-receptor family members and the signaling from these receptors induces NF-kappaB activation. However, the role of Fas in induction of NF-kappaB activation in HCC cells is not well understood. In this study, SK-Hep1, HepG2 or HLE cells were stimulated by anti-Fas agonistic antibody. Fas stimulation induced NF-kappaB activation in a dose-dependent manner in SK-Hep1 and HepG2 cell lines, but not in HLE cells. Anti-Fas agonistic antibody or the metabolic inhibitor, cyclo-heximide (CHX), failed to kill SK-Hep1 cells, but co-incubation with anti-Fas agonistic antibody and CHX was effective for induction of apoptosis. SK-Hep1 cell lines receiving Fas stimulation had increased viability, but the extent of cell proliferation was not dose-dependent. The observation suggests that Fas stimulation may contribute to HCC cell survival or proliferation.

Over-expression of Smac promotes TRAIL-induced cell death in human hepatocellular carcinoma.

The second mitochondria-derived activator of caspase, Smac, is an apoptosis-related protein. Smac releases inhibition of the IAP family from caspase-3 to induce apoptosis. Smac is expressed in some malignant tumor cells and is released from mitochondria into the cytosol after death receptor stimulation to promote apoptosis of tumor cells. In this study, we found down-regulated Smac protein expression in hepatocellular carcinoma (HCC) tissues, compared to that in non-tumor hepatic tissues. Simultaneously, caspase-3 expression also decreased in HCC tissues. HCC cell lines did not undergo apoptosis after TRAIL stimulation, although Smac was expressed in these HCC cells. Ectopic Smac alone did not induce cell death, but could sensitize HCC cells to TRAIL stimulation. With over-expression of Smac in HCC cells, TRAIL induced by 10% HCC cell death. The role of Smac in apoptosis signaling pathway in HCC cells warrants further study.

Hepatocellular carcinoma development in sustained viral responders to interferon therapy in patients with chronic hepatitis C.

The incidence of hepatocellular carcinoma (HCC) tends to decrease in sustained responders (SR) to interferon (IFN) therapy for chronic hepatitis C rather than in non-responders (NR). However, some SR develop HCC and their details and prognosis are not well-known, so we investigated such cases. Among 462 patients who underwent IFN therapy and were available for follow-up, 142 patients (30.7%) were SR and six of these (4.2%) developed HCCs. The interval between interferon therapy and diagnosis of HCC was 32-99 months (average 59.2 months). Five of the six cases were single HCCs sized 20-125 mm. The remainder was multiple HCCs. After initial treatment, five patients (83.3%) relapsed and three patients (60%) died due to the HCC. The interval between initial treatment and recurrence was 2-14 months (average 5.8 months). Among the three fatal cases, the interval between initial treatment and their death was 11-66 months (average 29.3 months). Though the prognosis of the one patient who did not relapse after initial treatment was good, the other five patients relapsed and three of them died due to the HCC. These results suggest that the prognosis of sustained responders who develop HCC after IFN therapy is not necessarily good, so close follow-up remains necessary, despite their response to IFN therapy.