The Cytotoxic and Anti-proliferative Effects of 3-Hydrogenkwadaphnin in K562 and Jurkat Cells Is Reduced by Guanosine

Combination therapy with TiO2 nanoparticles and cisplatin enhances chemotherapy response in murine melanoma models

BACKGROUND

Despite recent progressions in the treatment of melanoma, the response to conventional therapies and the long-term survival in melanoma patients still remain poor. Recently, the use of nanoparticles (NPs) has been highlighted for promoting the chemotherapeutic effects of cytotoxic drugs in melanoma. The aim of this study is to mechanistically evaluate the potential of titanium dioxide (TiO₂) nanoparticles (NPs) for enhancing chemotherapy effects in in vitro and in vivo models of murine melanoma.

METHODS

The F10 melanoma cells were exposed to different concentrations of TiO₂ NPs and/or cisplatin, then cell growth, cell viability, and cell death were evaluated. In parallel, C57BL/6 syngeneic melanoma mice were treated by TiO₂ NPs and/or cisplatin, and then drug responses, tumor size and mice's organs were studied pathologically. Autophagy was examined by evaluating the formation of autophagosomes and gene expression levels of autophagy markers (ATG5 and ATG6) by fluorescent microscopy and qPCR, respectively.

RESULTS

Nontoxic concentrations of TiO₂ NPs (50 µg/ml) promote anti-proliferative and cytotoxic effects of cisplatin in F10 melanoma cells, which is mediated through the induction of autophagy and necrotic cell death. Whereas TiO₂ NPs have no cytotoxic or metastatic effects in melanoma mice, its combination with cisplatin enhances drug responses (up to 50%), leading to higher inhibition of tumor growth compared with each monotherapy.

CONCLUSION

The combination of TiO₂ NP with cisplatin enhances chemotherapy response in both in vitro and in vivo melanoma models. In addition, autophagy plays an essential role during sensitizing melanoma cells to chemotherapy.

Cytotoxicity Evaluation of Essential Oil and its Component from Zingiber officinale Roscoe

Zingiber officinale Roscoe has been widely used as a folk medicine to treat various diseases, including cancer. This study aims to re-examine the therapeutic potential of co-administration of natural products and cancer chemotherapeutics. Candidate material for this project, α-zingiberene, was extracted from Zingiber officinale Roscoe, and α-zingiberene makes up 35.02 ± 0.30% of its total essential oil. α-Zingiberene showed low IC50 values, 60.6 ± 3.6, 46.2 ± 0.6, 172.0 ± 6.6, 80.3 ± 6.6 (μg/mL) in HeLa, SiHa, MCF-7 and HL-60 cells each. These values are a little bit higher than IC50 values of general essential oil in those cells. The treatment of α-zingiberene produced nucleosomal DNA fragmentation in SiHa cells, and the percentage of sub-diploid cells increased in a concentration-dependent manner in SiHa cells, hallmark features of apoptosis. Mitochondrial cytochrome c activation and an in vitro caspase-3 activity assay demonstrated that the activation of caspases accompanies the apoptotic effect of α-zingiberene, which mediates cell death. These results suggest that the apoptotic effect of α-zingiberene on SiHa cells may converge caspase-3 activation through the release of mitochondrial cytochrome c into cytoplasm. It is considered that anti-proliferative effect of α-zingiberene is a result of apoptotic effects, and α-zingiberene is worth furthermore study to develop it as cancer chemotherapeutics.

Cytotoxic Activity from Curcuma zedoaria Through Mitochondrial Activation on Ovarian Cancer Cells

α-Curcumene is one of the physiologically active components of Curcuma zedoaria, which is believed to perform anti-tumor activities, the mechanisms of which are poorly understood. In the present study, we investigated the mechanism of the apoptotic effect of α-curcumene on the growth of human overian cancer, SiHa cells. Upon treatment with α-curcumene, cell viability of SiHa cells was inhibited > 73% for 48 h incubation. α-Curcumene treatment showed a characteristic nucleosomal DNA fragmentation pattern and the percentage of sub-diploid cells was increased in a concentration-dependent manner, hallmark features of apoptosis. Mitochondrial cytochrome c activation and an in vitro caspase-3 activity assay demonstrated that the activation of caspases accompanies the apoptotic effect of α-curcumene, which mediates cell death. These results suggest that the apoptotic effect of α-curcumene on SiHa cells may converge caspase-3 activation through the release of mitochondrial cytochrome c.

Antiproliferative activity of the isofuranonaphthoquinone isolated from Bulbine frutescens against Jurkat T cells

Cancer is a major public health burden in both developed and developing countries. The quinone moiety has been shown to possess antitumor activity and several cancer drugs in clinical use contain this entity. The effect of isofuranonaphthoquinone isolated from Bulbine frutescens on Jurkat T cells was determined. Cells were exposed to the isofuranonaphthoquinone (IFNQ) at different concentrations. Significant antiproliferative effects were observed which were comparable to that of the anticancer drug 1,3-bis(2-chloroethyl)-1-nitrosourea (BCNU). A combination of IFNQ with BCNU produced synergistic effects which were observed after 72 hrs. It was also observed that combining IFNQ with reduced glutathione abolished the anticancer activity of the compound. It is, therefore, proposed that the isofuranonaphthoquinone may exert part of its effect by producing reactive oxygen species resulting in death of the cells as the effects of this compound were antagonized by reduced glutathione. An investigation on the effects of isofuranonaphthoquinone on glutathione transferase (GST) activity and drug efflux pumps showed that this compound exhibited inhibitory effects on both the GST and the drug efflux pumping activities. Thus, the isofuranonaphthoquinone showed cytotoxicity, works through inhibition of some cellular mechanisms, and could present a potential source of lead compounds for anticancer drug development.

3-Hydrogenkwadaphnine, a novel diterpene ester from Dendrostellera lessertii, its role in differentiation and apoptosis of KG1 cells

3-Hydrogenkwadaphnin (3-HK) (Fig. 1) is a daphnane-type diterpene ester isolated from the leaves of Dendrostellera lessertii (Thymelaeaceae) with differentiation and apoptotic potency among several leukemic cells without any measurable adverse effects on normal cells [Moosavi, M.A., Yazdanparast, R., Sanati, M.H., Nejad, A.S., 2005a. 3-Hydrogenkwadaphnin targets inosine 5'-monophosphate dehydrogenase and triggers post-G1 arrest apoptosis in human leukemia cell lines. Int. J. Biochem. Cell Biol. 37, 2366-2379]. In this study, we evaluated differentiating and apoptotic efficiency of a second new anti-proliferating agent from the same plant relative to 3-HK using acute myeloid leukemia (AML) KG1 cell line. 3-HK at 5-30 nM inhibited proliferation of KG1 cells after 24-96 h of treatment. NBT reducing assay and expression of cell surface markers (CD11b and CD14) confirmed that the inhibition of proliferation is associated with differentiation toward macrophage-like morphology. Regarding the relatively weaker potency of 3-HK in the induction of differentiation compared to that of the crude extract, we looked for additional compound(s) with similar properties in the crude extract. This effort led to isolation of the second compound from the leaves' extract with higher differentiating potency. The new compound inhibited proliferation of KG1 cells by almost 48+/-3.1% after 72 h of treatment with a single dose of 1.5 microg/ml. The treated cells differentiated along the monocyte/macrophage lineage based on the morphological features apparent after Wright-Giemsa staining, phagocytic activity and expression of cell surface markers as analyzed by flow cytometry. On the other hand, the results indicated that exposure of KG1 cells to either 3-HK or the new compound for 3-4 days induced apoptosis as assayed qualitatively by acridine orange/ethidium bromide (Ao/EtBr) double staining, agarose gel electrophoresis and quantitatively by Annexin-V technique and sub-G1 DNA staining using flow cytometry. Based on the present data, these two active constituents of D. lessertii have the novelty of being further evaluated for pharmaceutical applications.

Antimelanogenesis effect of Tunisian herb Thymelaea hirsuta extract on B16 murine melanoma cells

Skin pigmentation is the result of melanogenesis that occurs in melanocytes and/or melanoma cells. Although melanogenesis is necessary for the prevention of DNA damage and cancer caused by UV irradiation, excessive accumulation of melanin can also cause melanoma. Thus, we focused on the antimelanogenesis effect of an extract from Thymelaea hirsuta, a Tunisian herb. Murine melanoma B16 cells were treated with T. hirsuta extract, and then cell viability and synthesized melanin content were measured. We found that the T. hirsuta extract decreased the synthesized melanin content in B16 cells without cytotoxicity. Tyrosinase is a key enzyme of melanogenesis and extracellular signal-regulated kinase (ERK)-1/2 phosphorylation is known to be related to melanogenesis inhibition. To clarify its mechanism, we also determined ERK1/2 phosphorylation and tyrosinase expression level. ERK1/2 was immediately phosphorylated in cells just after treatment with the extract. The tyrosinase expression was inhibited after 24 h of stimulation with the extract. The T. hirsuta extract was fractionated, and we found that one fraction considerably decreased the melanin synthesis in B16 cells and that this fraction contains daphnanes as the main component. This indicates that our findings might be attributable to daphnanes.