Mohammad Akbar Hossain

Korean red ginseng extract induces apoptosis and decreases telomerase activity in human leukemia cells

AIM OF THIS STUDY Korean red ginseng (KRG, Panax ginseng C.A. Meyer Radix rubra) has been used to treat various diseases including cancer. However, the molecular mechanisms responsible for KRG extract induced apoptosis and telomerase inhibition remain unclear. MATERIALS AND METHODS The hot water extract from KRG was used to evaluate the mechanism of induction of apoptosis in U937 human leukemia cells and its effects on cyclooxgenase-2 (COX-2) and telomerase activity. RESULTS KRG extract treatment to U937 cells resulted in growth inhibition and induction of apoptosis in a concentration-dependent manner as measured by hemacytometer counts, MTT assay, fluorescence microscopy, agarose gel electrophoresis and flow cytometry analysis. The increase in apoptosis was associated with the down-regulation of antiapoptotic Bcl-2, Bcl-X(L), and IAPs family members, and the activation of caspase-3. KRG extract treatment also decreased the expression levels of COX-2 and inducible nitric oxide synthase. Furthermore, KRG extract treatment progressively down-regulated the expression of human telomerase reverse transcriptase, a main determinant of the telomerase enzymatic activity, with inhibiting the expression of c-Myc in a concentration-dependent manner. CONCLUSIONS These results provide important new insights into the possible molecular mechanisms of the anticancer activity of KRG extract.

Aspirin induces apoptosis in vitro and inhibits tumor growth of human hepatocellular carcinoma cells in a nude mouse xenograft model

Nonsteroidal anti-inflammatory drugs (NSAIDs) are known to induce apoptosis in a variety of cancer cells, including colon, prostate, breast and leukemia. Among them, aspirin, a classical NSAID, shows promise in cancer therapy in certain types of cancers. We hypothesized that aspirin might affect the growth of liver cancer cells since liver is the principal site for aspirin metabolism. Therefore, we investigated the effects of aspirin on the HepG2 human hepatocellular carcinoma cell line in vitro and the HepG2 cell xenograft model in BALB/c nude mice. We found that treatment with aspirin inhibited cell growth and induced apoptosis involving both extrinsic and intrinsic pathways as measured by DNA ladder formation, alteration in the Bax/Bcl-2 ratio, activation of the caspase activities and related protein expressions. In vivo antitumor activity assay also showed that aspirin resulted in significant tumor growth inhibition compared to the control. Oral administration of aspirin (100 mg/kg/day) caused a significant reduction in the growth of HepG2 tumors in nude mice. These findings suggest that aspirin may be used as a promising anticancer agent against liver cancer.

Baicalein, an active component of Scutellaria baicalensis Georgi, induces apoptosis in human colon cancer cells and prevents AOM/DSS-induced colon cancer in mice.

Flavonoids have been demonstrated to provide health benefits in humans. Baicalein (5,6,7-trihydroxyflavone) is a phenolic flavonoid compound derived mainly from the root of Scutellaria baicalensis Georgi, a medicinal plant traditionally used in oriental medicine. Baicalein is widely used in Korean and Chinese herbal medicines as anti-inflammatory and anticancer therapy. However, the molecular mechanisms of its activity remain poorly understood and warrant further investigation. This study was performed to investigate the anticancer effect of baicalein on HCT116 human colon cancer cells and the tumor preventing capacity of baicalein on colitis-associated cancer in mice. In in vivo experiments, we induced colon tumors in mice by azoxymethane (AOM) and dextran sulfate sodium (DSS) and evaluated the effects of baicalein on tumor growth. Baicalein treatment on HCT116 cells resulted in a concentration-dependent inhibition of cell growth and induction of apoptotic cell death. The induction of apoptosis was determined by morphological changes and cleavage of poly(ADP-ribose) polymerase. Baicalein also suppressed the activation of NF-κB through PPARγ activation. These results indicate that the anti-inflammatory effects of baicalein may be mediated through PPARγ activation. Finally, administration with baicalein significantly decreased the incidence of tumor formation with inflammation. Our findings suggest that baicalein is one of the candidates for the prevention of inflammation-associated colon carcinogenesis.

Aspirin enhances doxorubicin-induced apoptosis and reduces tumor growth in human hepatocellular carcinoma cells in vitro and in vivo

Combined therapy with multiple drugs is a common practice in the treatment of cancer, which can achieve better therapeutic effects than a single drug, and can reduce the side effects as well as drug resistance. This study aimed to determine whether aspirin (ASA) shows synergism with doxorubicin (DOX) in HepG2 human hepatocellular carcinoma cells in vitro and in a HepG2 cell xenograft model in BALB/c nude mice. When treated in combination, DOX (0.25 nmol/ml) and ASA (5 µmol/ml) produced strong synergy in growth inhibition, cell cycle arrest and importantly, apoptosis in vitro in comparison to single treatments. Moreover, ASA (100 mg/kg/day orally) and DOX (1.2 mg/kg biweekly ip) induced synergistic antitumor activity in the HepG2 cell xenograft model in nude mice. Therefore, the combination of ASA and DOX could be used as a novel combination regimen which provides a strong anticancer synergy in the treatment of hepatocellular carcinoma.

A chenodeoxycholic derivative, HS-1200, induces apoptosis and cell cycle modulation via Egr-1 gene expression control on human hepatoma cells

We previously reported that HS-1200, a synthetic chenodeoxycholic acid derivative, has apoptosis-inducing activity in various human cancer cells. The present study was undertaken to examine whether HS-1200 had an anticancer effect on HepG2 (wild-type p53) and Hep3B (p53 deleted) human hepatoma cells. Treatment of both cells with HS-1200 resulted in growth inhibition and induction of apoptosis as measured by MTT assay, nuclear staining, DNA fragmentation and flow cytometry analysis. The increase in apoptosis was associated with the alteration in the ratio of Bcl-2/Bax protein expression. In addition, flow cytometry analysis indicated that HS-1200 induced G1 phase arrest in both cells. When analyzing the expression of cell cycle-related proteins, we found that HS-1200 reduced the expression levels of cyclin D1, cyclin A, and Cdk2. HS-1200 treatment also caused an increase in the expression levels of p21 WAF1/CIP1 in HepG2 cells in a p53-dependent manner and in Hep3B cells in a p53-independent manner. Moreover, the expression level of p27 KIP1 was increased in both cell lines. We also observed that HS-1200 decreased the levels of cyclooxygenase (COX)-2 mRNA and protein expression. Furthermore, HS-1200 treatment markedly induced the Egr-1 expression at an early time point, and the increased expression levels of p53, p21 WAF1/CIP1, p27 KIP1, and COX-2 after treatment with HS-1200 were completely inhibited in HepG2 cells and partially inhibited in Hep3B cells by silencing of Egr-1, respectively. Taken together, these findings provide important new insights into the possible molecular mechanisms of the anticancer activity of the synthetic bile acid derivative, HS-1200, through Egr-1 regulation.

HS-1793, a resveratrol analogue, induces cell cycle arrest and apoptotic cell death in human breast cancer cells

Resveratrol, a polyphenolic compound, is a naturally occurring phytochemical and is found in a variety of plants, including food such as grapes, berries and peanuts. It has gained much attention for its potential anticancer activity against various types of human cancer. However, the usefulness of resveratrol as a chemotherapeutic agent is limited by its photosensitivity and metabolic instability. In this study the effects of a synthetic analogue of resveratrol, HS-1793, on the proliferation and apoptotic cell death were investigated using MCF-7 (wild-type p53) and MDA-MB-231 (mutant p53) human breast cancer cells. HS-1793 inhibited cell growth and induced apoptotic cell death in a concentration-dependent manner. The induction of apoptosis was determined by morphological changes, cleavage of poly(ADP-ribose) poly-merase, alteration of Bax/Bcl-2 expression ratio and caspase activities. Flow cytometric analysis revealed that HS-1793 induced G2/M arrest in the cell cycle progression in both types of cells. Of note, HS-1793 induced p53/p21WAF1/CIP1-dependent apoptosis in MCF-7 cells, whereas it exhibited p53-independent apoptosis in MDA-MB-231 cells. Furthermore, HS-1793 showed more potent anticancer effects in several aspects compared to resveratrol in MCF-7 and MDA-MB-231 cells. Thus, these findings suggest that HS-1793 has potential as a candidate chemotherapeutic agent against human breast cancer.

A novel resveratrol analogue, HS-1793, inhibits hypoxia-induced HIF-1α and VEGF expression, and migration in human prostate cancer cells

In many studies, resveratrol has been shown to have a chemopreventive effect in various types of cancer cells. However, the biological activity of resveratrol is limited by its photosensitivity and metabolic instability. This study investigated the effects of a novel analogue of resveratrol, HS-1793, on the expression of HIF-1α and vascular endothelial growth factor (VEGF) in PC-3 human prostate cancer cells. Hypoxic condition induced HIF-1α protein level in PC-3 cells in a time-dependent manner, and treatment with HS-1793 markedly decreased HIF-1α expression levels. HS-1793 also inhibited VEGF level. Mechanistically, HS-1793 inhibited HIF-1α and VEGF expression through multiple mechanisms. Firstly, HS-1793 inhibited phosphorylation of PI3K and Akt in PC-3 cells. Furthermore, HS-1793 substantially induced HIF-1α protein degradation through the proteasome pathway. Finally, HS-1793 inhibited hypoxia-induced PC-3 cell migration. These data suggest that HS-1793 may inhibit human prostate cancer progression and angiogenesis by inhibiting the expression of HIF-1α and VEGF. Moreover, HS-1793 showed more potent effects than resveratrol on the cytotoxic effects on PC-3 cells. Taken together, these results implied that HS-1793, a novel analogue of resveratrol, may be a new potent chemopreventive agent against human prostate cancer cells.

2,3,6-Tribromo-4,5-dihydroxybenzyl methyl ether induces growth inhibition and apoptosis in MCF-7 human breast cancer cells

In this study, we investigated the effects of 2,3,6-tribromo-4,5-dihydroxybenzyl methyl ether (TDB), isolated fromSymphyocladia latiuscula (marine red algae), on the proliferation of MCF-7 human breast cancer cells. TDB treatment for 48 h inhibited cancer cell growth and induced DNA fragmentation. Furthermore, morphological characterizations such as apoptotic bodies and membrane blebs were shown by electronic microscopy. TDB-induced apoptosis in the MCF-7 cells was closely linked with the down-regulation of Bcl-2 protein expression and the cle⇑age of caspase-3 substrates, with poly(ADP-ribose) polymerase cleavage occurring by TDB treatment. TDB treatment also caused a marked increase in the level ofp21WAF1/CIP1 protein in a p53-dependent manner. In addition, the upregulation ofp21WAF1/CIP1 in the MCF-7 cells was related to a decrease in c-Myc protein in a dose-dependent manner. Based on our data, TDB is a good candidate for further evaluation as an effective chemotherapeutic agent, acting through the induction of apoptosis.

A novel hydroxamic acid derivative, MHY218, induces apoptosis and cell cycle arrest through downregulation of NF-κB in HCT116 human colon cancer cells

Colorectal cancer (CRC) is one of the most common malignant diseases and frequent cause of cancer deaths in the world. In spite of the significant advances in conventional therapeutic approaches to CRC, most patients ultimately die of their disease. There is a need to develop novel preventive approaches for this malignancy. This study was carried out to investigate the anticancer effect of MHY218, a hydroxamic acid derivative, in HCT116 human colon cancer cells. Treatment of cells with MHY218 resulted in growth inhibition and induction of apoptosis in a concentration-dependent manner. MHY218 induced G2/M phase arrest in the cell cycle progression which was observed by flow cytometry analysis, and a decrease in the protein expression of cyclin B1 and its activating partners Cdc25C and Cdc2. MHY218 also caused an increase in the expression levels of p21(WAF1/CIP1), a G2/M phase inhibitor, in a p53-independent pathway. The induction of apoptosis was observed by decreased viability, DNA fragmentation, cleavage of poly(ADP-ribose) polymerase, alteration in the ratio of Bax/Bcl-2 protein expression, and activation of caspase-3, -8 and -9. In addition, MHY218 treatment showed downregulation of the expression levels of the transcription factor nuclear factor-kappa B (NF-κB) in the nucleus, which has been reported to be implicated in the apoptotic cell death of several types of cancer cells, suppression of TNF-α-induced NF-κB activation, inhibition of cyclooxygenase-2 expression, repression of matrix metalloproteinase-9 activation and decrease of 5-lipoxygenase in a concentration-dependent manner. These results suggest that MHY218 may be a useful candidate to be used in the chemoprevention and/or treatment of colon cancer.

4-Hydroxynonenal Induces Endothelial Cell Apoptosis via ROS and Peroxynitrite Generation

The formation of reactive lipid aldehydes, 4-hydroxynonenal (HNE) is shown to be derived from fatty acid hydroperoxides through the oxidative process. Among its known effects in cytotoxicity, HNE has been implicated in apoptotic cell death. To delineate its putative role as a potential mediator, we investigated the mechanism by which HNE induces apoptosis of endothelial cells (ECs). The anti-proliferative effects of HNE were tested through MTT assay after exposure to various concentrations (5~15 μM) of HNE. We observed apoptotic bodies with propidium iodide staining, and measured the HNE induction of endothelial apoptosis by flow cytometry assay. We observed that cells exposed to HNE for 24 hr resulted in increased poly(ADP-ribose) polymerase cleavage and up-regulation of Bax. Data on the HNE action strongly indicated the involvement of reactive species, namely, intracellular ROS, nitrite, and peroxynitrite. To obtain evidence on the implication of ROS and peroxynitrite in HNE-induced apoptosis, a ROS scavenger, N-acetylcysteine (NAC), and a peroxynitrite scavenger, penicillamine, were tested. Results clearly indicate that the induction of apoptosis by HNE was effectively inhibited by NAC and penicillamine. Based on the present data, we conclude that the endothelial apoptosis induced by HNE involves both ROS generation and peroxynitrite activity. Our new data could lead to a redefinition of HNE action on apoptosis in ECs.