Pheophorbide a, an active compound isolated fromScutellaria barbata, possesses photodynamic activities by inducing apoptosis in human hepatocellular carcinoma

Pheophorbide a-Mediated Photodynamic Therapy Triggers HLA Class I-Restricted Antigen Presentation in Human Hepatocellular Carcinoma

The immunomodulatory effects of photodynamic therapy (PDT) have been reported in several photosensitizers. Pheophorbide a (Pa), a chlorophyll derivative, shows antitumor effects on a number of human cancers in a PDT approach (Pa-PDT); however, the potential effect of Pa-PDT on the anticancer immunity has never been studied. In the present work, the underlying action mechanism of Pa-PDT was systemically investigated with a human hepatoma cell line HepG2. We found that Pa-PDT significantly inhibited the growth of HepG2 cells with a half maximal inhibitory concentration/endoplasmic reticulum of 0.35 microM at 24 hours by the induction of apoptosis, as shown by externalization of phosphatidylserine, release of mitochondrial cytochrome c, and activation of the caspases cascade in the treated cells. Interestingly, using two-dimensional polyacrylamide gel electrophoresis analysis, a 57-kDa disulfide-isomerase-like ER resident protein (ERp57) that belongs to the HLA class I-restricted antigen-processing machinery was found to be mediated during the Pa-PDT treatment. This activation of antigen presentation was confirmed by Western blot analysis and immunostaining. Furthermore, a cross-presentation of antigen with HLA class I proteins and 70-kDa heat shock protein was found in Pa-PDT-treated cells, as shown by the confocal microscopic observation and immunoprecipitation assay. Nevertheless, the immunogenicity of HepG2 cells was increased by Pa-PDT treatment that triggered phagocytic capture by human macrophages. Our findings provide the first evidence that Pa-PDT can trigger both apoptosis and cancer immunity in the tumor host.

Herbal medicine and hepatocellular carcinoma: applications and challenges

Use of herbal medicine in the treatment of liver cancer has a long tradition. The compounds derived from the herb and herbal composites are of considerable interest among oncologists. In the past, certain herbal compounds and herbal composite formulas have been studied through in vitro and in vivo as an anti-hepatocellular carcinoma (HCC) agent, enhancing our knowledge about their biologic functions and targets. However there is a significant distinction between the herbal medicine and the herbal production even though both are the plant-based remedies used in the practice. In this article, for the sake of clarity, the effective herbal compounds and herbal composite formulas against HCC are discussed, with emphasizing the basic conceptions of herbal medicine in order to have a better understanding of the prevention and treatment of HCC by herbal active compounds and herbal composite formulas.

Preparation of carotenoids and chlorophylls from Gynostemma pentaphyllum (Thunb.) Makino and their antiproliferation effect on hepatoma cell

A preparative column chromatographic method for isolation of carotenoids and chlorophylls from Gynostemma pentaphyllum, a traditional Chinese herb, was developed to evaluate their antiproliferative effects on the hepatoma cell Hep3B. An open column containing 70 g of magnesium oxide-diatomaceous earth (1:2.5, wt/wt) was used to elute carotenoid with 2% ethanol in ethyl acetate and chlorophyll with 50% ethanol in acetone. After high-performance liquid chromatography-mass spectrometry analysis, the carotenoid fraction was composed of all-trans- and cis-isomers of lutein, α-carotene, and β-carotene as well as epoxy-containing carotenoids, while the chlorophyll fraction consisted of chlorophylls a and b and their derivatives. Both carotenoid and chlorophyll fractions as well as lutein and chlorophyll a standards at 50-100 μg/mL were effective against Hep3B cells with a dose-dependent response with the following order: carotenoid fraction > chlorophyll fraction > lutein > chlorophyll a. For all treatments, the cell cycle was arrested in the G₀/G₁ phase, with Hep3B cells undergoing necrosis or apoptosis.

Photo-activated pheophorbide-a, an active component of Scutellaria barbata, enhances apoptosis via the suppression of ERK-mediated autophagy in the estrogen receptor-negative human breast adenocarcinoma cells MDA-MB-231

AIM OF THE STUDY

Scutellaria barbata is a traditional Chinese medicine for cancer treatments. Pheophorbide-a (Pa), one of the active components isolated from this herbal medicine has been proposed to be a potential natural photosensitizer for photodynamic therapy. The anti-tumor effect of pheophorbide-a based photodynamic therapy (Pa-PDT) has been successfully demonstrated in a wide range of human malignant cell lines. However, the effectiveness of Pa-PDT has not yet been evaluated on human breast cancer, which is documented as the second common and the fifth most lethal cancer worldwide.

MATERIALS AND METHODS

The cytotoxicity of Pa-PDT was evaluated by using an estrogen receptor (ER)-negative human breast adenocarcinoma cell line MDA-MB-231. The involvement of mitochondria was revealed by the change of mitochondrial membrane potential and the increase of intracellular reactive oxygen species (ROS). The hallmarks of apoptosis, ER stress and autophagy were also assessed by DNA fragmentation, Western blotting, and immunostaining assays.

RESULTS

Pa-PDT showed inhibitory effect on the growth of MDA-MB-231 cells with an IC(50) value of 0.5 microM at 24h. Mitogen-activated protein kinase (MAPK) pathway was found to be triggered, where activation of c-Jun N-terminal kinase (JNK) and inhibition of extracellular signal-regulated kinase (ERK) were occurred in the Pa-PDT-treated cells. Our findings suggested that Pa-PDT exhibited its anti-tumor effects by the activation of mitochondria-mediated apoptosis and the ERK-mediated autophagy in MDA-MB-231 cells.

CONCLUSION

The present study suggested Pa-PDT is a potential protocol for the late phase human breast cancer, and it is the first study to demonstrate the Pa-PDT induced autophagy contributed to the anti-tumor effects of Pa-PDT on human cancer cells.

First report of a haemagglutinin-induced apoptotic pathway in breast cancer cells

A dimeric 64 kDa HA (haemagglutinin) was isolated with a high yield from dried Phaseolus vulgaris cultivar 'French bean number 35' seeds. It inhibited the proliferation of hepatoma HepG2 cells and breast cancer MCF-7 cells with an IC50 of 100 and 2 microM respectively. After exposure of MCF-7 cells to the HA for 24 h, a number of changes were detected in the cells. Growth arrest in the G0/G1 and G2/M phases was observed. The number of cells undergoing early apoptosis and late apoptosis increased. Disruption of the mitochondrial transmembrane potential and disorganization of the inner mitochondrial membrane were induced. Western-blot analysis disclosed that the HA induced apoptosis through the death receptor-mediated pathway.

Photodynamic therapy inhibits P-glycoprotein mediated multidrug resistance via JNK activation in human hepatocellular carcinoma using the photosensitizer pheophorbide a

Background

Multidrug resistance (MDR) is frequently observed after prolonged treatment in human hepatoma with conventional anti-tumor drugs, and photodynamic therapy (PDT) is a recently suggested alternative to overcome MDR. The therapeutic potential of PDT was evaluated in a multidrug resistance (MDR) human hepatoma cell line R-HepG2 with photosensitizer pheophorbide a (Pa).

Results

Our results demonstrated that intracellular accumulation of Pa was not reduced by the overexpression of P-glycoprotein. Pa-based PDT (Pa-PDT) significantly inhibited the growth of R-HepG2 cells with an IC50 value of 0.6 μM. Mechanistic study demonstrated that genomic DNA fragmentation and phosphatidylserine externalization occurred where increase of intracellular singlet oxygen level triggers the phosphorylation of c-Jun N-terminal Kinase (JNK) and leads to activation of intrinsic apoptotic caspases cascade during the Pa-PDT treatment. The cytotoxicity of Pa-PDT, accumulation of sub-G1 population, and depolarization of mitochondrial membrane could be inhibited by JNK inhibitor in the Pa-PDT treated cells. Interestingly, the Pa-PDT induced JNK activation showed inhibitory effect on MDR by the down-regulation of P-glycoprotein in R-HepG2 cells in a dose-dependent manner. In addition, significant reduction of tumor size was obtained in Pa-PDT treated R-HepG2-bearing nude mice with no significant damages in liver and heart.

Conclusion

In summary, our findings provided the first evidence that PDT could inhibit the MDR activity by down-regulating the expression of P-glycoprotein via JNK activation using pheophorbide a as the photosensitizer, and our work proved that Pa-PDT inhibited the growth of MDR hepatoma cells by mitochondrial-mediated apoptosis induction.

Naturally occurring chlorophyll derivatives inhibit aflatoxin B1-DNA adduct formation in hepatoma cells

The inhibitory effects of four chlorophyll derivatives (chlorophyllide [Chlide] a and b and pheophorbide [Pho] a and b) on aflatoxin B1 (AFB1)-DNA adduct formation, and on the modulation of hepatic glutathione S-transferase (GST) were evaluated in murine hepatoma (Hepa-1) cells. Enzyme-linked immunosorbent assay showed that pretreatment with Chlide or Pho significantly reduced the formation of AFB1-DNA adducts, and that Pho was the most potent inhibitor. However, wash-out prior to adding AFB1 totally eliminated inhibition by Childe and partially eliminated inhibition by Pho, indicating that the inhibitory effect of Chlide, and to some extent Pho, was mediated through direct trapping of AFB1. Furthermore, spectrophotometric analysis showed that Pho treatment could increase GST activity in Hepa-1 cells. These observations indicate that the chlorophyll derivatives studied may attenuate AFB1-induced DNA damage in the Hepa-1 cell by direct trapping of AFB1. Pho provided additional protection not only by direct trapping, but also by increasing GST activity against hepatic AFB1 metabolites.

Polymeric micelles of zinc protoporphyrin for tumor targeted delivery based on EPR effect and singlet oxygen generation

Polymeric micelles of zinc protoporphyrin (ZnPP) with water soluble biocompatible and amphiphilic polymer, polyethylene glycol (PEG) demonstrated unique characteristics to target tumor tissues selectively based on the enhanced permeability and retention (EPR) effect. The micellar macromolecular drug of ZnPP (SMA-ZnPP and PEG-ZnPP) previously showed notable anticancer activity as a consequence of selective tumor targeting ability and its potent HO-1 inhibitory potential, resulting in suppressed biliverdin/bilirubin production in tumors thereby leading to oxystress induced tumor cell killing. Furthermore, recent findings also showed that ZnPP efficiently generated reactive singlet oxygen under illumination of visible light, laser, or xenon light source, which could augment its oxystress induced cell killing abilities. In the present paper, we report the synergistic effects of light induced photosensitizing capabilities and HO-1 inhibitory potentials of these unique micelles when tested in vitro and in vivo on tumor models under localized, mild illumination conditions using a tungsten-xenon light source. The results indicate that these water soluble polymeric micelles of ZnPP portend to be promising candidates for targeted chemotherapy as well as photodynamic therapy against superficial tumors as well as solid tumors located at light penetrable depths.

Anti-proliferative and pro-apoptotic effect of Smilax glabra Roxb. extract on hepatoma cell lines

Smilax glabra Roxb. (SGR) is the root of a traditional Chinese herb, referred to as tu fu ling in Chinese medicine. It is an inexpensive traditional Chinese medicine commonly used for the treatment of liver diseases, and a few studies have indicated that SGR has anti-hepatocarcinogenic and anti-cancer growth activities. In the current study, raw SGR plant was extracted with Accelerate Solvent Extractor, and the molecular mechanism by which S. glabra Roxb. extract (SGRE) has an anti-proliferative effect on the human hepatoma cell lines, HepG2 and Hep3B, was determined. We showed that SGRE inhibited HepG2 and Hep3B cell growth by causing cell-cycle arrest at either S phase or S/G2 transition and induced apoptosis, as evidenced by a DNA fragmentation assay. SGRE-induced apoptosis by alternation of mitochondrial transmembrane depolarization, release of mitochondrial cytochrome c, activation of caspase-3, and cleavage of poly(ADP-ribose) polymerase. The SGRE-mediated mitochondria-caspase dependent apoptotic pathway also involved activation of p38, JNK, and ERK mitogen-activated protein kinase signaling. Isometric compounds of astilbin (flavonoids) and smilagenin (saponin) have been identified as the main chemical constituents in SGRE by HPLC-MS/MS. These results have identified, for the first time, the biological activity of SGRE in HepG2 and Hep3B cells and should lead to further development of SGR for liver disease therapy.

Protective effects of an herbal formulation of Radix Astragali , Radix Codonopsis and Cortex Lycii on streptozotocin-induced apoptosis in pancreatic β -cells: an implication for its treatment of diabetes mellitus

Hyperglycemia is one of the main causes of oxidative stress in type 2 diabetes mellitus. During hyperglycemia, the increased level of various reducing sugars in the blood enhances the production of reactive oxygen species (ROS) and triggers tissue damage, especially in pancreatic beta-cells. Streptozotocin (STZ) is a diabetogen that causes diabetes mellitus via ROS-induced apoptosis in beta-cells. In this study, SR10, an herbal formulation consisting of the aqueous extracts of Radix Astragali, Radix Codonopsis and Cortex Lycii was examined for its antidiabetic effects in vitro. SR10 treatment resulted in significant enhancement of survival rate of rat pancreatic beta-cells which were treated by streptozotocin. SR10 apparently reduced apoptosis of streptozotocin-treated beta-cells by decreasing DNA fragmentation, sub-G(1) peak area and percentage of apoptotic cells. Nitric oxide (NO) production in streptozotocin-treated cells was inhibited by SR10 via the suppression of the expression of inducible nitric oxide synthase (iNOS). The implication of SR10 in treating type 2 diabetes mellitus was discussed.

Saxifragifolin B from Androsace umbellata induced apoptosis on human hepatoma cells

Bioassay-guided phytochemical study of Androsace umbellata led to the successful isolation of saxifragifolin B (SB) for the first time. The anti-tumor effect of SB was firstly reported that it was shown to have potent cytotoxicity on human hepatoma HepG2 cells with IC50 value of 11.9 microM at 24 h. Mechanistic studies were conducted, the accumulation of sub-G1 population and the externalization of phosphatidylserine suggested that SB exerted its cytotoxic effect by induction of programmed cell death, which was confirmed by activation of PARP and caspase-3. Furthermore, SB-induced apoptosis on HepG2 cells was mediated by activation of caspase-8 and -9, mitochondrial membrane potential (Deltapsim) collapse and the leakage of cytochrome c. In summary, this study provided evidence that SB isolated from A. umbellata could induce apoptosis on human hepatoma HepG2 cells and described the molecular mechanism. Our finding revealed the potential of SB as new chemotherapeutic agent for human hepatoma.