Jian Ye Zhang

Anthracenedione derivative 1403P-3 induces apoptosis in KB and KBv200 cells via reactive oxygen species-independent mitochondrial pathway and death receptor pathway

Anthracenedione derivatives are potent cytotoxic agents to tumour cells. In this study, we investigated the anticancer activities of anthracenedione derivative 1403P-3 separated from the secondary metabolites of the mangrove endophytic fungus No. 1403. Our results demonatrated that 1403P-3 showed potent cytotoxicity not only to human epidermoid carcinoma drug-sensitive parental KB cells but also to multidrug resistant (MDR) KBv200 cells and the IC50 values were 19.66 and 19.27 μM, respectively. Further research indicated that 1403P-3 induced apoptosis in KB cells and KBv200 cells confirmed by Hoechst 33258 staining, detection of DNA fragmentation and cleavage of poly (ADP-ribose) polymerase (PARP). Furthermore, apoptosis triggered by 1403P-3 was characterized by the loss of mitochondrial membrane potential (ΔΨm), release of cytochrome c, cleavage of Bid, and activation of caspases-2, -3, -7, -8 and -9. Z-IETD-FMK, caspase-8 inhibitor could inhibit the activation of caspase-2 and cleavage of Bid induced by 1403P-3. However, activation of caspase-9 and cleavage of PARP caused by 1403P-3 were not inhibited by Z-IETD-FMK. Additionally, 1403P-3 did not influence the expression level of Bcl-2 and Bax. It is noteworthy that 1403P-3 decreased the generation of reactive oxygen species (ROS) in KB cells and KBv200 cells. DNA binding assay exhibited that apoptosis induced by 1403P-3 was not involved in intercalating to DNA. In summary, 1403P-3 induced apoptosis of KB cells and KBv200 cells through mitochondrial pathway and death receptor pathway. Furthermore, the mitochondrial pathway was independent of reactive oxygen species and activation of caspase-8.

Secalonic Acid D induced leukemia cell apoptosis and cell cycle arrest of G1 with involvement of GSK-3β/β-catenin/c-Myc pathway

The anticancer activities of secalonic acid D separated from the secondary metabolites of the mangrove endophytic fungus No. ZSU44 were investigated in this study. Secalonic acid D showed potent cytotoxicity to HL60 and K562 cells, and the IC50 values were 0.38 and 0.43 μmol/L, respectively. Annexin V-FITC/PI assay and western blot indicated that secalonic acid D induced apoptosis in HL60 and K562 cells.. In addition, secalonic acid D led to cell cycle arrest of G1 phase related to downregulation of c-Myc. Moreover, our data indicated that downregulation of c-Myc and cell cycle arrest of G1 phase were caused not by formation of G-quadruplex structures but by activation of GSK-3β followed by degradation of β-catenin.

Anthracenedione Derivatives as Anticancer Agents Isolated from Secondary Metabolites of the Mangrove Endophytic Fungi

In this article, we report anticancer activity of 14 anthracenedione derivatives separated from the secondary metabolites of the mangrove endophytic fungi Halorosellinia sp. (No. 1403) and Guignardia sp. (No. 4382). Some of them inhibited potently the growth of KB and KBv200 cells, among which compound 6 displayed strong cytotoxicity with IC50 values of 3.17 and 3.21 μM to KB and KBv200 cells, respectively. Furthermore, we demonstrate that the mechanism involved in the apoptosis induced by compound 6 is probably related to mitochondrial dysfunction. Additionally, the structure-activity relationships of these compounds are discussed.

Blockade of Her2/neu binding to Hsp90 by emodin azide methyl anthraquinone derivative induces proteasomal degradation of Her2/neu

Overexpression of HER2/neu, a transmembrane tyrosine kinase acting as a coreceptor for other EGFR family members, is well-known to be associated with a poor prognosis in cancer. In the present study, we observed that emodin AMAD, a novel emodin azide methyl anthraquinone derivative, extracted from natures giant knotweed rhizome of traditional Chinese herbs, potently decreased Her2/neu protein in dose- and time-dependent manners and also inhibited the downstream MAPK and PI3K-Akt signaling pathway. Intriguingly, reverse transcription-PCR and protein turnover assay revealed that the decrease of Her2/neu was independent of mRNA level but primarily owing to its protein stability. Meanwhile, proteasome inhibitor MG132 but not lysosome inhibitor chloroquine could restore Her2/neu and polyubiquitination of Her2/neu was augmented during emodin AMAD treatment. Furthermore, immunofluorescence study with anti-Her2/neu antibody showed that emodin AMAD disturbed the subcellular distribution of Her2/neu, with decreased location in the plasma membrane. Molecular docking studies predicted that AMAD can interact with the ATP-binding pocket of both Hsp90 and Her2/neu. Importantly, coimmunoprecipitation and immunofluorescence study revealed that emodin AMAD markedly impaired the binding between Hsp90 and Her2/neu and could bind to both Hsp90 and Her2/neu as reinforced by molecular modeling studies. In addition, combination of emodin AMAD treatment and siRNA against Her2 synergistically inhibited proliferation and induced apoptosis. Taken together, these data suggest that blockade of Her2/neu binding to Hsp90 and following proteasomal degradation of Her2/neu were involved in emodin AMAD-induced apoptosis in Her2/neu-overexpressing cancer cells. Our results provide suggestions that emodin AMAD could be promising as a new targeting therapeutic strategy in the treatment of Her2/neu-overexpressing cancers.

Anticancer Effect and Structure-Activity Analysis of Marine Products Isolated from Metabolites of Mangrove Fungi in the South China Sea

Marine-derived fungi provide plenty of structurally unique and biologically active secondary metabolites. We screened 87 marine products from mangrove fungi in the South China Sea for anticancer activity by MTT assay. 14% of the compounds (11/86) exhibited a potent activity against cancer in vitro. Importantly, some compounds such as compounds 78 and 81 appeared to be promising for treating cancer patients with multidrug resistance, which should encourage more efforts to isolate promising candidates for further development as clinically useful chemotherapeutic drugs. Furthermore, DNA intercalation was not involved in their anticancer activities, as determined by DNA binding assay. On the other hand, the structure-activity analysis indicated that the hydroxyl group was important for their cytotoxic activity and that bulky functional groups such as phenyl rings could result in a loss of biological activity, which will direct the further development of marine product-based derivatives.

Secalonic acid D reduced the percentage of side populations by down-regulating the expression of ABCG2

The side population cells characterized by the ability to transport Hoechst 33342 out of cells have been identified as cancer stem-like cells. ABCG2 is found to confer the side population (SP) phenotype, multidrug resistance (MDR) and tumor recurrence. In this study, we found secalonic acid D (SAD), a metabolite of marine-derived mangrove endophytic fungus, showed potent anticancer effect on ABCB1-, ABCC1- and ABCG2- overexpressing multidrug resistance cells by MTT assay. Furthermore, SAD could down-regulate the expression of ABCG2 and decrease the percentage of SP cells in lung cancer cells. The MTT assay showed the sorted SP cells were sensitive to SAD and we also found SAD could inhibit the sphere-forming ability of SP cells. Although SAD did not affect the expression of ABCG2 mRNA, it shortened the half-life of ABCG2 protein by activating calpain 1. These results implicated that SAD could be developed as a leading compound to target cancer stem cells and would be a promising agent to treat lung cancer patients.

Euphorbia factor L1 reverses ABCB1‐mediated multidrug resistance involving interaction with ABCB1 independent of ABCB1 downregualtion

Euphorbia factor L1 (EFL1) belongs to diterpenoids of genus Euphorbia. In this article, its reversal activity against ABCB1‐mediated MDR in KBv200 and MCF‐7/adr cells was reported. However, EFL1 did not alter the sensitivity of KB and MCF‐7 cells to chemotherapeutic agents. Meanwhile, EFL1 significantly increased accumulation of doxorubicin and rhodamine 123 in KBv200 and MCF‐7/adr cells, showing no siginficant influence on that of KB and MCF‐7 cells. Furthermore, EFL1 could enhance the ATP hydrolysis activity of ABCB1 stimulated by verapamil. At the same time, EFL1 inhibited the efflux of ABCB1 in KBv200 and MCF‐7/adr cells. In addition, EFL1 did not downregulate expression of ABCB1 in KBv200 and MCF‐7/adr cells either in mRNA or protein level. J. Cell. Biochem. 112: 1076–1083, 2011.

Structure identification of euphorbia factor L3 and its induction of apoptosis through the mitochondrial pathway

In this article, we have focused on the structure identification of Euphorbia factor L3 belonging to the lathyrane diterpenoids isolated from Caper Euphorbia Seed. Its anticancer activity in vitro against lung cancer A549 cells was also investigated and the IC50 values were 34.04 ± 3.99 μM. Furthermore, Euphorbia factor L3 could induce apoptosis in A549 cells via the mitochondrial pathway including loss of mitochondrial potential and release of cytochrome c.