Isolation of ckit-positive cardiosphere-forming cells from human atrial biopsy.

There is increasing interest in developing cell-based therapies to regenerate functional muscle and blood vessels in infarcted dysfunctional myocardium, using stem cells resident in the adult heart. The objective of our study was to identify an easy and cost-effective method for the isolation and expansion of human adult cardiac-resident stem cells. The cells were isolated from right atrial biopsy samples obtained from patients with ischemic heart disease, who were undergoing coronary artery bypass grafting. Two different isolation methods, enzymatic and nonenzymatic, were employed. The cell yield and cluster formation were not significantly different with either of the techniques used for cell isolation. The nonenzymatic method is recommended because of its simplicity and lower cost compared to the enzymatic method.

Radiosensitizing effects of plumbagin in cervical cancer cells is through modulation of apoptotic pathway.

Radiotherapy is the primary line of cancer treatment for cervical cancer and is known to induce cell death in tumors. Radiotherapy is however limited by the total dose that can be given without damaging normal tissue. Plumbagin, a naturally occurring naphthaquinone, has been reported to have free radical producing properties. Hence we hypothesized that plumbagin could also have properties that could modify effects of radiation on cervical cancer cells. Radiation in combination with plumbagin may thus have treatment augmenting effects. Results from our studies have shown that a lower dose of radiation in combination with plumbagin could induce apoptosis more effectively compared to a higher dose of radiation alone. Plumbagin in combination with 2 Gy of radiation was very effective in inducing apoptosis, when compared to a higher radiation dose of 10 Gy alone. This combination also showed a fivefold increase in the activation of caspase 3 in C33A cells. Activation of effector caspases confirms that the induction of apoptosis by irradiation and plumbagin involves caspase-dependent pathways. Expression of apoptotic regulatory molecules Bcl-2, Bax and Survivin was also modulated by plumbagin in combination with radiation. In summary, this study shows that a combination of plumbagin and radiation augmented cell growth inhibition compared to higher radiation dose alone, thus indicating that plumbagin may be a potential radiosensitizer acting through the induction of apoptosis.

Molecular mechanism of emodin action: transition from laxative ingredient to an antitumor agent.

Anthraquinones represent a large family of compounds having diverse biological properties. Emodin (1,3,8-trihydroxy-6-methylanthraquinone) is a naturally occurring anthraquinone present in the roots and barks of numerous plants, molds, and lichens, and an active ingredient of various Chinese herbs. Earlier studies have documented mutagenic/genotoxic effects of emodin, mainly in bacterial system. Emodin, first assigned to be a specific inhibitor of the protein tyrosine kinase p65lck, has now a number of cellular targets interacting with it. Its inhibitory effect on mammalian cell cycle modulation in specific oncogene overexpressed cells formed the basis of using this compound as an anticancer agent. Identification of apoptosis as a mechanism of elimination of cells treated with cytotoxic agents initiated new studies deciphering the mechanism of apoptosis induced by emodin. At present, its role in combination chemotherapy with standard drugs to reduce toxicity and to enhance efficacy is pursued vigorously. Its additional inhibitory effects on angiogenic and metastasis regulatory processes make emodin a sensible candidate as a specific blocker of tumor-associated events. Additionally, because of its quinone structure, emodin may interfere with electron transport process and in altering cellular redox status, which may account for its cytotoxic properties in different systems. However, there is no documentation available which reviews the biological activities of emodin, in particular, its growth inhibitory effects. This review is an attempt to analyze the biological properties of emodin, a molecule offering a broad therapeutic window, which in future may become a member of anticancer armamentarium.

Plumbagin induces reactive oxygen species, which mediate apoptosis in human cervical cancer cells.

There is an emerging evidence that plumbagin (5-hydroxy-2-methyl-1, 4-naphthoquinone) may have potential as a chemotherapeutic agent. However, the growth inhibitory mechanisms of plumbagin have remained unexplored. The aim of the study was to determine whether plumbagin-induced cell death in human cervical cancer cell line, ME-180, exhibited biochemical characteristics of apoptosis and to check whether N-acetyl-l-cysteine (NAC), which is a free radical scavenger, can reverse the cytotoxic effects of plumbagin. It can be concluded from the results that plumbagin inhibits the growth of ME-180 cells in a concentration and time-dependent manner. The cytotoxic effect of plumbagin induced cell death is through the generation of reactive oxygen species (ROS) and subsequent induction of apoptosis as demonstrated by the present data. Treatment of cells with plumbagin caused loss of mitochondrial membrane potential (DeltaPsi(m)), and morphological changes characteristic of apoptosis, such as the translocation of phosphatidyl serine, nuclear condensation, and DNA fragmentation. Moreover, plumbagin-induced apoptosis involved release of mitochondrial cytochrome c and apoptosis inducing factor (AIF), thus activation of caspase-dependent and -independent pathways, as shown by the plumbagin-mediated activation of caspase-3 and -9. Our results also show that pretreatment of ME-180 cells with NAC blocks plumbagin-induced loss of DeltaPsi(m) and subsequent release of cytochrome c, AIF, and caspase-9 and -3 activation, thus inhibiting the apoptotic ability of plumbagin.

Allicin (from garlic) induces caspase-mediated apoptosis in cancer cells.

Garlic (Allium sativum) has been used for centuries for treating various ailments, and its consumption is said to reduce cancer risk and its extracts and components effectively block experimentally induced tumors. Allicin, the major component present in freshly crushed garlic, is one of the most biologically active compounds of garlic. We found that allicin inhibited the growth of cancer cells of murine and human origin. Allicin induced the formation of apoptotic bodies, nuclear condensation and a typical DNA ladder in cancer cells. Furthermore, activation of caspases-3, -8 and -9 and cleavage of poly(ADP-ribose) polymerase were induced by allicin. The present results demonstrating allicin-induced apoptosis of cancer cells are novel since allicin has not been shown to induce apoptosis previously. Our results also provide a mechanistic basis for the antiproliferative effects of allicin and partly account for the chemopreventive action of garlic extracts reported by earlier workers.

Antisense blocking of BRCA1 enhances sensitivity to plumbagin but not tamoxifen in BG-1 ovarian cancer cells.

Previous studies have shown that reduction in BRCA1 mRNA and protein can result in increased proliferation of BG-1 ovarian cancer cells in both in vitro and in vivo conditions, suggesting that BRCA1 may normally act as a growth inhibitor in these cells. Also, there are other reports that suggest that wild-type BRCA1 protein may repress estrogen receptor (ER) function either directly or indirectly. However, response to antiestrogen drugs in BRCA1-blocked ER-positive ovarian cancer cells has not been reported, and this served as the rationale for this study. We analyzed the effect of tamoxifen, emodin, and plumbagin in BRCA1-blocked ER-positive BG-1 ovarian cancer cells. For all three drugs, BRCA1-blocked cells were more sensitive than the corresponding control cells as assessed by MTT assay; however, only plumbagin showed a statistically significant difference in mean viability (P < 0.05). All three drugs induced loss of mitochondrial membrane potential (DeltaPsi(m)), nuclear condensation, DNA fragmentation, and morphological changes, as observed after 6 h of drug treatment, suggesting apoptosis induction in both BRCA1-blocked and control cells. However, apoptosis induction was greater in BRCA1-blocked cells, the efficacy being in the order of plumbagin > tamoxifen > emodin. The dose of plumbagin needed to kill 50% was 5 microM in the control cells and 2.68 microM for the BRCA1-blocked cells, indicating that the latter was about twofold more sensitive to plumbagin than the wild-type cells. This throws light on the fact that plumbagin may have chemotherapeutic potential as an anticancer agent in BRCA1-mutated ovarian cancer patients.

Emodin induces apoptosis of human cervical cancer cells through poly(ADP-ribose) polymerase cleavage and activation of caspase-9.

Emodin (1,3,8-trihydroxy-6-methylanthraquinone) is an active herbal component traditionally used in China for treating various ailments. Emodin exerts antiproliferative effects in many cancer cell lines and the actual molecular mechanism of which is still not clear. Since apoptosis could be a potential mechanism to explain these effects, we tested whether emodin induces cell death in human cervical cancer cells. Our results suggest that emodin exerts antiproliferative effects in human cervical cancer cells. Emodin inhibited DNA synthesis and induced apoptosis as demonstrated by increased nuclear condensation, annexin binding and DNA fragmentation in Bu 25TK cells in the presence of emodin. Moreover, we demonstrate for the first time in human cervical cancer cells that the apoptotic pathway involved in emodin-induced apoptosis is caspase-dependent and presumably through the mitochondrial pathway, as shown by the activation of caspases-3, -9 and cleavage of poly(ADP-ribose) polymerase.