Bufadienolides bufalin and cinobufagin are cardiotonic steroids isolated from the skin and parotid venom glands of the toad Bufo bufo gargarizans Cantor. They have been shown to induce a wide spectrum of cancer cell apoptosis. However, the detailed molecular mechanisms of inducing apoptosis in hepatocellular carcinoma (HCC) are still unclear. In the present study, the apoptosis-inducing effect of bufalin and cinobufagin on HCC cell line HepG 2 was investigated. We found bufalin and cinobufagin induced marked changes in apoptotic morphology and significantly increased the proportion of apoptotic cells. This apoptotic induction was associated with an increase in Fas, Bax and Bid expression, a decrease in Bcl-2 expression, disruption of the mitochondrial membrane potential, release of cytochrome c, activation of caspase-3, -8, -9 and -10, and the cleavage of poly(ADP-ribose)polymerase (PARP), which indicated that bufalin and cinobufagin induced apoptosis through both Fas-and mitochondria-mediated pathways. In addition, caspase activation during bufalin-and cinobufagin-induced apoptosis was further confirmed by caspase-3 inhibitor Z-DEVD-FMK, caspase-8 inhibitor Z-IETD-FMK, caspase-9 inhibitor Z-LEHD-FMK and caspase-10 inhibitor Z-AEVD-FMK. The results showed that bufalin-and cinobufagin-induced apoptosis was blocked by these inhibitors and particularly by caspase-10 inhibitor. Taken together, bufalin and cinobufagin induce apoptosis of HepG 2 cells via both Fas-and mitochondria-mediated pathways, and a Fasmediated caspase-10-dependent pathway might play a crucial role. (Cancer Sci 2011; 102: 951-958) H epatocellular carcinoma (HCC) is one of the most common malignancies worldwide with 600 000 deaths per year, and its incidence is still on the rise.(1) Surgical treatments, such as liver resection and transplantation, are the first-line therapeutic strategies for HCC. However, the postoperative survival rate is only 30-40% at 5 years and recurrence is quite common in patients who have had a resection.(2) In addition, because HCC is a relatively chemo-resistant tumor and highly refractory to cytotoxic chemotherapy, systemic cytotoxic chemotherapy agents are minimally effective at improving the survival of patients with advanced HCC.(3,4) Therefore, development of novel chemotherapeutic agents and more effective therapies for the treatment of HCC are urgently needed. Recently, traditional Chinese medicines and their active components have attracted a great deal of attention as candidates for HCC therapy.(5)
Indocyanine green (ICG) is a photothermal agent, photosensitizer, and fluorescence imaging probe which shows specific accumulation in hepatocellular carcinoma (HCC) cells. We recently developed a photodynamic therapy (PDT) using ICG and near-infrared (NIR) laser as a new anti-cancer treatment for HCC. However, the molecular mechanism underlying this effect needs to be elucidated. HuH-7 cells, a well-differentiated human HCC cell line, were transplanted subcutaneously into BALB/c-nu/nu mice for in vivo experiment. ICG was administered 24 h before NIR irradiation. The irradiation was performed at three tumor locations by 823-nm NIR laser on days 1 and 7. The temperature of HuH-7 xenografts increased to 48.5 °C 3 minutes after ICG-NIR irradiation start. Reactive oxygen species (ROS) production was detected after ICG-NIR irradiation both in vitro and in vivo. There was certain anti-tumor effect and ROS production even under cooling conditions. Repeated NIR irradiation increased the cell toxicity of ICG-NIR therapy; the mean tumor volume on day 9 was significantly smaller after ICG-NIR irradiation compared to tumor without irradiation (87 mm3 vs. 1332 mm3; p = 0.01) in HCC mice xenografts model. ICG-NIR therapy induced apoptosis in HCC cells via a photothermal effect and oxidative stress. Repeated ICG-NIR irradiation enhanced the anti-tumor effect.
Des‐γ‐carboxyprothrombin (DCP) is known as a tumour marker for hepatocellular carcinoma (HCC). Various tumour markers have been developed for serological diagnosis of cancers, including HCC, in order to increase the survival rate of cancer patients. The currently recommended combined testing of DCP and α‐fetoprotein (AFP) or Lens culinaris agglutinin‐reactive fraction of α‐fetoprotein has been established to diagnose HCC. This combined testing using several tumour markers helps to increase the sensitivity of diagnosis of HCC, thus significantly increasing the clinical usefulness of DCP. The excessive production of DCP may be related to worse tumour behaviour, such as the presence of vascular invasion and intrahepatic metastasis of HCC cells. A high level of DCP was suggested to be useful as one of the factors in new recipient selection criteria of liver transplantation. The clinical use of DCP, therefore, might play a vital role in predicting tumour behaviour in patients with HCC. That said, the basic mechanism of DCP production has not been fully clarified. Various factors such as vitamin K2 and γ‐glutamyl carboxylase may contribute to the production of DCP and have a complex relationship. Moreover, recent studies have revealed that DCP functions as a growth factor and might play significant roles in cancer progression. Thus, DCP represents a potential target of drug discovery to establish new chemotherapeutic strategy for HCC. However, various issues have to be resolved to construct a novel therapy for HCC‐targeting DCP. Innovation is required to make further progress in examining DCP.
The prevalence of hepatocellular carcinoma (HCC) worldwide parallels that of persistent infection with the hepatitis B virus (HBV) and/or hepatitis C virus (HCV). According to recommendations by the World Health Organization guidelines for HBV/HCV, alpha-fetoprotein (AFP) testing and abdominal ultrasound should be performed in routine surveillance of HCC every 6 mo for high-risk patients. These examinations have also been recommended worldwide by many other HCC guidelines over the past few decades. In recent years, however, the role of AFP in HCC surveillance and diagnosis has diminished due to advances in imaging modalities. AFP was excluded from the surveillance and/or diagnostic criteria in the HCC guidelines published by the American Association for the Study of Liver Diseases in 2010, the European Association for the Study of the Liver in 2012, and the National Comprehensive Cancer Network in 2014. Other biomarkers, including the Lens culinaris agglutinin-reactive fraction of AFP (AFP-L3), des-γ-carboxyprothrombin, Dickkopf-1, midkine, and microRNA, are being studied in this regard. Furthermore, increasing attention has focused on the clinical utility of biomarkers as pre-treatment predictors for tumor recurrence and as post-treatment monitors. Serum and tissue-based biomarkers and genomics may aid in the diagnosis of HCC, determination of patient prognosis, and selection of appropriate treatment. However, further studies are needed to better characterize the accuracy and potential role of these approaches in clinical practice.
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