Dynamic influence of Rhein lysinate on HeLa cells.

In a previous study, it was demonstrated that Rhein lysinate (RHL) inhibited HeLa cell proliferation via a specific mechanism. The aim of the present study was to clarify the mechanism of RHL by investigating its effect on mitochondrial damage and cell apoptosis. The results indicated that RHL inhibited cell growth and proliferation in HeLa cells. HeLa cells treated with RHL developed extensive vacuolization in a dose- and time-dependent manner. Ultrastructure analysis using transmission electron microscopy revealed that the vacuoles observed were damaged mitochondria and endoplasmic reticulum. The effects of RHL on mitochondria were further confirmed by a decrease in mitochondrial membrane potential and increased generation of reactive oxygen species. The mitochondrial proteome was analyzed, and the results demonstrated that the expression of the cytoskeletal protein keratin and dermal papilla derived protein 12 (associated with the oxidation-reduction process), which are associated with mitochondrial structure and function, were decreased compared with the untreated control group. Hoechst staining, flow cytometry and western blotting also revealed that apoptosis was induced at 24 h following RHL treatment. These results confirm that RHL toxicity in HeLa cells is a dynamic process. Vacuolar degeneration appeared in HeLa cells treated with 160 µmol/l RHL during the first 6 h and with the extension of RHL treatment, cell apoptosis was presented at ~24 h in HeLa cells.

Rhein lysinate protects renal function in diabetic nephropathy of KK/HlJ mice.

The purpose of the present study was to assess the protective effects of rhein lysinate (RHL) in a KK/HlJ mouse model of diabetic nephropathy (DN) and to explore its mechanism of action. A total of 4 groups were established: C57BL/J control, the KK/HlJ model and 25 and 50 mg/kg/day RHL-treated KK/HlJ groups. The KK/HlJ mouse model of DN was established by streptozotocin injection, followed by maintenance on a specific diet. The albumin-to-creatinine ratio (ACR) was determined at 5 weeks and at 16 weeks, the kidneys were harvested, and morphological examination and immunohistochemical analysis were performed. The levels of malondialdehyde (MDA), as well as superoxide dismutase (SOD) and glutathione peroxidase (GSH-px) activities in the kidneys were measured using appropriate assay kits. The expression of inflammatory factors and associated proteins was analyzed using western blot analysis. At 5 weeks, the levels of ACR in KK/HlJ mice were increased, which was inhibited by treatment with RHL. Treatment with RHL (50 mg/kg/day) decreased the body weight of KK/HlJ mice. Compared with the C57BL/J control, the KK/HlJ model mice had a significantly lower activity of SOD and GSH-px in the kidneys, but had significantly higher levels of MDA. Treatment of KK/HlJ mice with RHL significantly increased the activities SOD and GSH-px, and reduced the MAD level in the kidneys. Renal tubular epithelial cell edema was observed in KK/HlJ mice but not in C57BL/J mice. RHL decreased the incidence of renal tubular epithelial cell edema and significantly decreased the expression of TNF-α and IL-6 as well as the expression and phosphorylation of NF-κB in the kidneys. Therefore, DN is associated with the expression of inflammatory factors, renal tubular epithelial cell edema and renal dysfunction in KK/HlJ mice. RHL improves renal function by decreasing kidney inflammation.

Rhein lysinate decreases inflammation and adipose infiltration in KK/HlJ diabetic mice with non-alcoholic fatty liver disease.

The objective of this study was to investigate the protective effects of rhein lysinate (RHL) on the liver. Mice were divided into four groups: C57BL/J control, the KK/HlJ diabetic model, and 25 and 50 mg/kg/day RHL-treated KK/HlJ groups. The KK/HlJ diabetic mouse model was made by injecting STZ and feeding mice diabetic food. At 16 weeks, mice were sacrificed and their livers were harvested. The results indicated that compared with the C57BL/J control group, the body weights, liver weights and liver weight-to-body weight ratio were increased in KK/HlJ diabetic mice; however, these values were decreased following treatment with RHL. Compared with the C57BL/J control, KK/HlJ diabetic mice had a significantly lower level of SOD and GSH-px in their livers, but had a significantly higher level of MDA. However, these effects were ameliorated by RHL. Hepatic adipose infiltration was observed in KK/HlJ mice, but not in C57BL/J mice. RHL decreased the incidence of hepatic adipose infiltration and significantly decreased the expression of TNF-α, IL-6, NF-κB, SREBP-1c, and Fas, as well as the phosphorylation of NF-κB in the liver. In conclusion, RHL can improve hepatic function by decreasing hepatic adipose infiltration and the expression of inflammatory factors.

Effects of rhein lysinate on D-galactose-induced aging mice.

The aim of the present study was to investigate the anti-aging effects of rhein lysinate (RHL), and to explore its mechanism of action in a D-galactose-induced aging mouse model. Aging was induced by D-galactose (100 mg/kg/day) that was subcutaneously injected to animals for 8 weeks. RHL was simultaneously administered once a day by intragastric gavage. The appetite, mental condition, body weight and organ index of the mice were monitored. Superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) activities were determined, and the levels of malondialdehyde (MDA) in the liver, kidney and serum were measured by appropriate assay kits. Western blot analysis was used to detect proteins associated with age. The results indicated that RHL may improve the appetite, mental state and organ conditions of the model mice, improve the activities of SOD and GSH-Px, reduce MDA levels and modulate the expression of age-associated proteins (Sirtuin 1, p21 and p16) in D-galactose-induced mice. Therefore, RHL may be effective at suppressing the aging process through a combination of enhancing antioxidant activity, scavenging free radicals and modulating aging-associated gene expression.

Antitumor activity of rhein lysinate against human glioma U87 cells in vitro and in vivo.

In previous studies, we demonstrated that rhein lysinate (RHL), the salt of rhein and lysine that is easily dissolved in water, inhibited the growth of tumor cells derived from breast and ovarian cancer, hepatocellular carcinoma, cervical cancer and lung carcinoma. Based on these observations, human glioma U87 cells and a xenograft model in BALB/c nude mice were used to examine the antitumor activity of RHL against human glioma. Notably, RHL statistically significantly suppressed the growth of human glioma U87 xenografts in BALB/c nude mice. In vitro, there was a significant reduction in cell proliferation after treatment with RHL in a dose- and time-dependent manner. The overall growth inhibition was correlated with the increase in reactive oxygen species (ROS) production and cell apoptosis. The apoptosis- and cell cycle-related proteins including BAX and Bim were increased, whereas Bcl-2 and cyclin D were decreased in the RHL-treated cells. The results demonstrated that RHL is highly effective against the growth of human glioma U87 xenografts in BALB/c nude mice. The potent antitumor activity of RHL may be mediated through downregulation of Bcl-2 and cyclin D expression and upregulation of BAX and Bim expression.

Protective effect of bicyclol against bile duct ligation-induced hepatic fibrosis in rats.

AIM: To evaluate the protective effect of bicyclol against bile duct ligation (BDL)-induced hepatic fibrosis in rats. METHODS: Sprague-Dawley male rats underwent BDL and sham-operated animals were used as healthy controls. The BDL rats were divided into two groups which received sterilized PBS or bicyclol (100 mg/kg per day) orally for two consecutive weeks. Serum, urine and bile were collected for biochemical determinations. Liver tissues were collected for histological analysis and a whole genome oligonucleotide microarray assay. Reverse transcription-polymerase chain reaction and Western blotting were used to verify the expression of liver fibrosis-related genes. RESULTS: Treatment with bicyclol significantly reduced liver fibrosis and bile duct proliferation after BDL. The levels of alanine aminotransferase (127.7 ± 72.3 vs 230.4 ± 69.6, P < 0.05) and aspartate aminotransferase (696.8 ± 232.6 vs 1032.6 ± 165.8, P < 0.05) were also decreased by treatment with bicyclol in comparison to PBS. The expression changes of 45 fibrogenic genes and several fibrogenesis-related pathways were reversed by bicyclol in the microarray assay. Bicyclol significantly reduced liver mRNA and/or protein expression levels of collagen 1a1, matrix metalloproteinase 2, tumor necrosis factor, tissue inhibitors of metalloproteinases 2, transforming growth factor-ß1 and α-smooth muscle actin. CONCLUSION: Bicyclol significantly attenuates BDL-induced liver fibrosis by reversing fibrogenic gene expression. These findings suggest that bicyclol might be an effective anti-fibrotic drug for the treatment of cholestatic liver disease.

Gambogic Acid lysinate induces apoptosis in breast cancer mcf-7 cells by increasing reactive oxygen species.

Gambogic acid (GA) inhibits the proliferation of various human cancer cells. However, because of its water insolubility, the antitumor efficacy of GA is limited. Objectives. To investigate the antitumor activity of gambogic acid lysinate (GAL) and its mechanism. Methods. Inhibition of cell proliferation was determined by MTT assay; intracellular ROS level was detected by staining cells with DCFH-DA; cell apoptosis was determined by flow cytometer and the mechanism of GAL was investigated by Western blot. Results. GAL inhibited the proliferation of MCF-7 cells with IC50 values 1.46 µmol/L comparable with GA (IC50, 1.16 µmol/L). GAL promoted the production of ROS; however NAC could remove ROS and block the effect of GAL. GAL inhibited the expression of SIRT1 but increased the phosphorylation of FOXO3a and the expression of p27Kip1. At knockdown of FOXO3a, cell apoptosis induced by GAL can be partly blocked. In addition it also enhanced the cleavage of caspase-3. Conclusions. GAL inhibited MCF-7 cell proliferation and induced MCF-7 cell apoptosis by increasing ROS level which could induce cell apoptosis by both SIRT1/FOXO3a/p27Kip1 and caspase-3 signal pathway. These results suggested that GAL might be useful as a modulation agent in cancer chemotherapy.

The protection of Rhein lysinate to liver in diabetic mice induced by high-fat diet and streptozotocin.

Rhein lysinate (RHL) is the salt of lysine and rhein and the objective of this study was to investigate the protection of RHL to liver in diabetic mice. The model of type 2 diabetes was established by high-fat diet and streptozotocin treatment. Malondialdehyde, superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) were measured using a spectrophotometer. Inflammatory factors (TNF-α and IL-6) and related proteins (ERK1/2 and SREBP-1c) were analyzed by Western blot. Tissue profile was determined by hematoxylin and eosin staining and accumulation of fat was examined by Nile red staining. The results indicated that plasma glucose levels of type 2 diabetic mice were over 13.9 mM. Compared with model group, plasma glucose levels were decreased, however insulin levels were increased in RHL (25 and 50 mg/kg)-treated group. Elevated plasma triglyceride and cholesterol were also markedly attenuated after RHL treatment. The activities of SOD and GSH-Px of livers were increased after RHL treatment. Livers of RHL-treated mice had more normal structure and less steatosis than that of diabetic mice. Moreover, RHL decreased the expression of TNF-α and IL-6 and the phosphorylation of SREBP-1c and ERK1/2. In conclusion, RHL has a noticeable hepatic protection in diabetic mice.

KNDC1 knockdown protects human umbilical vein endothelial cells from senescence.

KNDC1 (kinase noncatalytic C-lobe domain containing 1), a brain-specific Ras guanine nucleotide exchange factor, controls the negative regulation of neuronal dendrite growth. However, the effect of KNDC1 on cellular senescence remains to be elucidated. The present study investigated the impact of KNDC1 knockdown on human endothelial cell senescence and the mechanisms underlying this effect. Human umbilical vein endothelial cells (HUVECs) cultured in vitro were used as a model of biological aging. Senescence­associated ß-galactosidase staining was used to detect cellular senescence and flow cytometry was employed to determine cell cycle progression. Quantitative polymerase chain reaction (qPCR) and western blot analysis were utilized to investigate mRNA transcription and protein expression. In the HUVECs, a senescence-like phenotypes developed with increasing passage number in vitro, which were associated with a progressive increase in the transcription and expression of KNDC1. KNDC1 knockdown promoted cell proliferation and partially reversed cellular senescence and cell cycle arrest in the G0/G1 phase in aging HUVECs. Investigations into the mechanism underlying this effect demonstrated that KNDC1 knockdown promoted HUVEC proliferation via the extracellular signal-regulated kinase signaling pathway and delayed HUVEC senescence by inhibiting the p53-p21-p16 transduction cascade. In addition, the promotion of the capillary tube network formation and the increased expression of endothelial nitric oxide synthase revealed that the activity and function of endothelial cells were enhanced. In conclusion, KNDC1 knockdown delayed endothelial cell senescence and promoted HUVEC activity and function. These results demonstrated that KNDC1 may be a novel therapeutic target for the development of agents to extend human life.

Synergy of Taxol and rhein lysinate associated with the downregulation of ERK activation in lung carcinoma cells.

In previous studies we observed that rhein lysinate (RHL), a salt of rhein and lysine that is easily dissolved in water, inhibited the growth of tumor cells in breast cancer, ovarian cancer, hepatocellular carcinoma and cervical cancer. The present study aimed to investigate the effects of RHL on H460 and A549 non-small cell lung cancer (NSCLC) cells using a combination of RHL and Taxol. A 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-tetrazolium bromide (MTT) assay was used to determine the growth inhibition effect of the drugs in the H460 and A549 cells. Cell apoptosis was analyzed by flow cytometry combined with fluorescein-isothiocyanate-Annexin V/propidium iodide (PI) staining. The expression levels of proteins were detected by western blotting. There was a significant reduction in the proliferation of the NSCLC cell lines treated with a combination of Taxol and RHL. The overall growth inhibition was directly correlated with apoptotic cell death. RHL potentiated Taxol-induced cell killing by reducing extracellular signal-regulated kinase (ERK) activity and increasing the levels of cleaved poly(ADP-ribose) polymerase (PARP) and caspase-3. Notably, the results for the Bcl-2 and NF-κB proteins also showed downregulation in the combined treatment group compared with the single-agent treatment and the untreated control groups. The present results showed that RHL potentiates the growth inhibition induced by Taxol in NSCLC cells and showed that this synergy may be associated with the downregulation of ERK activation.

Bortezomid enhances the efficacy of lidamycin against human multiple myeloma cells.

The proteasome inhibitor bortezomib has been applied successfully to treat multiple myeloma (MM). Its synergistic effects with other anticancer drugs have been studied widely. In the present study, it was found that lidamycin (LDM), a member of the enediyne antibiotic family, showed much more potent cytotoxicity than bortezomib to MM cell lines: U266 and SKO-007. Here, we investigated the potential synergy of bortezomib and LDM on MM cells. The results showed that cotreatment of bortezomib and LDM synergistically induced cytotoxicity and apoptosis in MM cell lines, followed by enhanced caspase-3 cleavage and degradation of poly-ADP-ribose polymerase together with the decreased nuclear factor-κB protein. These two drugs synergistically induced apoptosis, which was associated with enhanced activation of two mitogen-activated protein kinases: p38 mitogen-activated protein kinase and c-Jun NH(2)-terminal kinase. Moreover, bortezomib plus LDM synergistically induced apoptosis was also associated with downregulation of extracellular signal-regulated kinase, and induction of endoplasmic reticulum stress response. Overall, our results indicate that the combined regimen of bortezomib and LDM might be a potential therapeutic remedy for the treatment of MM.

Rhein inhibits the expression of vascular cell adhesion molecule 1 in human umbilical vein endothelial cells with or without lipopolysaccharide stimulation.

Reducing the expression of endothelial cell adhesion molecules (ECAMs) is known to decrease inflammation-induced vascular complications. In this study, we explored whether rhein can reduce the inflammation-induced expression of ECAMs in human umbilical vein endothelial cells (HUVECs) with or without lipopolysaccharide (LPS) stimulation. HUVECs were treated with different concentrations of rhein with or without 2.5 µg/ml LPS stimulation. Cell viability was assayed using the MTT method. Real-time PCR and Western blot analysis were used to measure the transcription and expression levels of ECAMs, including intercellular adhesion molecule-1 (ICAM-1), vascular cell adhesion molecule-1 (VCAM-1), E-SELECTIN and related signaling proteins. The results indicated that rhein (0-20 µmol/L) and LPS (0-10 µg/ml) had no effect on the viability of HUVECs. LPS could promote the expression of VCAM-1, ICAM-1 and E-SELECTIN. Rhein appeared to target VCAM-1, ICAM-1 and E-SELECTIN, with the transcription and expression of all three factors being reduced by the rhein treatment (10 and 20 µmol/L). The transcription and expression of VCAM-1 were also reduced by treatment with rhein (10 and 20 µmol/L) in the presence of LPS stimulation. In conclusion, rhein treatment reduced the expression of VCAM-1 in HUVECs via a p38-dependent pathway.

Rhein lysinate increases the median survival time of SAMP10 mice: protective role in the kidney.

AIM: To investigate the protective effects of rhein lysinate (RHL), a major bioactive constituent of the rhizome of rhubarb (Rheum palmatum Linn or Rheum tanguticum Maxim), against kidney impairment in senescence-prone inbred strain 10 (SAMP10) mice. METHODS: SAMP10 mice were orally administered RHL (25 or 50 mg/kg) daily until 50% of the mice died. Senescence-resistant inbred strain 1 (SAMR1) mice administered no drug were taken as control. The kidneys were harvested after animal death, and examined morphologically and with immunochemical assays. The levels of MAD, SOD and GSH-px in the kidneys were measured with a photometric method. The expression of inflammatory factors and related proteins in the kidneys was analyzed using Western blotting. RESULTS: Treatment of SAMP10 mice with RHL had no effect on the body weight or phenotype. However, RHL significantly prolonged the median survival time of SAMP10 mice by approximately 25%, as compared to untreated SAMP10 mice. Compared SAMR1 mice, SAMP10 mice had a significantly lower level of SOD in the kidneys, but had no significant difference in the MDA or GSH-px levels. Treatment of SAMP10 mice with RHL significantly reduced the MAD level, and increased the SOD and GSH-px levels in the kidneys. Glomerulonephritis was observed in SAMP10 mice but not in SAMR1 mice. RHL decreased the incidence of glomerulonephritis, and significantly decreased the levels of TNF-α, IL-6, NF-κB, collagen types I and III in the kidneys. CONCLUSION: Accelerated senescence is associated with glomerulonephritis in SAMP10 mice, and RHL prolongs their median survival time by reducing the severity of glomerulonephritis.

Effects of Rhein lysinate on H2O2-induced cellular senescence of human umbilical vascular endothelial cells.

AIM: To observe the effect of Rhein lysinate (RHL) on cellular senescence of human umbilical vascular endothelial cells (HUVECs) and elucidate its action mechanism. METHODS: Cell viability was determined using MTT assay. The expression levels of Sirt1 mRNA and protein were measured by RT-PCR and Western blot, respectively. Senescence associated (SA)-ß-galactosidase activity was detected to evaluate cell senescence. Apoptosis and cell cycle progression were determined using flow cytometry. RESULTS: Treatment with RHL (10 µmol/L) for 48 h significantly increased the proliferation of HUVECs. In contrast, treatment with H2O2 (25, 50 and 100 µmol/L) for 6 d dose-dependently increased ß-galactosidase positive cells. Spontaneous cell senescence appeared as the cell passage increased. Pre-treatment with RHL (10 µmol/L) reversed H2O2 or increased cell passage-induced cell senescence. H2O2(100 µmol/L) significantly arrested HUVECs at G(1) phase (73.8% vs 64.6% in the vehicle group), which was blocked by RHL (10 µmol/L). RHL (5 and 10 µmol/L) enhanced both mRNA transcription and protein expression of Sirt1. H2O2 (100 µmol/L) significantly decreased Sirt1 expression, and induced up-regulation of p53 acetylation and p16(INK4a), which were blocked by pre-treatment with RHL (10 µmol/L). Interference with siRNA for Sirt1 abolished the effect of RHL. H2O2 (100 µmol/L) did not induce HUVEC apoptosis. The expression of apoptosis-associated proteins, such as p53, p21, Bcl-2, and Bax, did not significantly change in the presence of H(2)O(2) (100 µmol/L) or RHL (10 µmol/L). CONCLUSION: RHL protected HUVECs against cellular senescence induced by H2O2, via up-regulation of Sirt1 expression and down-regulation of the expression of acetyl-p53 and p16(INK4a).

Rhein lysinate induced S-phase arrest and increased the anti-tumor activity of 5-FU in HeLa cells.

Rhein lysinate (RHL), easily dissolved in water, is one of the anthraquinones, and has been shown to have anti-tumor activity in different human cancer cell lines. In the present study, we observed that RHL could cause vacuolar degeneration in HeLa cells, which was not observed in human umbilical vein endothelial cells (HUVECs) and other cell lines (SKOV-3 and SK-BR-3). Therefore, the purpose of this study was to investigate the anti-tumor effect of rhein lysinate on human cervix cancer HeLa cells. The results indicated that RHL could induce HeLa cell S-phase arrest and RHL (higher than 80 µM) also induced HeLa cell G2/M-phase arrest in a dose-dependent manner. Compared to the HeLa cells, RHL induced HUVECs G1-phase arrest at all dose levels tested in a dose-dependent manner. Treatment with RHL led to a significant S or G2/M-phase arrest through promoting the expression of p53 and p21 and the phosphorylation of p53. Moreover, 80 µM RHL could increase 5-FU anti-tumor activity. In conclusion, RHL could be a novel chemotherapeutic drug candidate for the treatment of human cervix cancer in the future.

Inhibition of mouse embryonic carcinoma cell growth by lidamycin through down-regulation of embryonic stem cell-like genes Oct4, Sox2 and Myc.

Lidamycin (LDM, also known as C-1027) as an anti-cancer agent inhibits growth in a variety of cancer cells by inducing apoptosis and cell cycle arrest. In this study we demonstrated that inhibition of mouse embryonic carcinoma (EC) cell growth using LDM at low concentrations can be attributed to a loss of the cell's self-renewal capability but not to apoptosis or cell death, which can be correlated to the down-regulation of embryonic stem (ES) cell-like genes Oct4, Sox2 and c-Myc. MTT assays showed that LDM inhibited the growth of mouse P19 EC cells in a time- and dose-dependent manner. The EC cells exposed to a low dose (0.01 nM) of LDM lost their capability to generate colonies, as evidenced by the colony forming assay. Flow cytometer analyses demonstrated that LDM induced G1 arrest in exposed EC cells without apoptosis. Real-time qPCR, Western blotting and immunocytochemistry revealed that Oct4, Sox2 and c-Myc were down-regulated in LDM-exposed EC cells, but not adriamycin (ADM)-exposed cells. Furthermore, a combination of the low dose of LDM and ADM significantly reduced the proliferation of the cancer cells than single-agent treatment. This suggested that synergy of ADM and LDM improved chemotherapy. Taking together, our results indicate that LDM can reduce the capability for self-renewal that mouse EC cells possess through the repression of ES cell-like genes, thereby inhibiting carcinoma cell growth. This data also suggests that LDM might have potential for application in CSC-based therapy and be a useful tool for studying ES cell pluripotency and differentiation.

Rhein lysinate inhibits cell growth by modulating various mitogen-activated protein kinases in cervical cancer cells.

In previous studies, we found that rhein lysinate (RHL; the salt of rhein and lysine, easily dissolved in water) inhibited the growth of tumor cells in breast and ovarian cancer and hepatocellular carcinoma. This study aimed to investigate the effect of RHL on the growth of human cervical carcinoma HeLa cells and any underlying mechanisms. RHL inhibited the growth of HeLa cells in a dose- and time-dependent manner. It was also noted that RHL induced apoptosis in HeLa cells in a dose-dependent manner. Mechanistically, RHL triggered HeLa cell apoptosis by increasing the levels of cleaved poly ADP-ribose polymerase (PARP) and caspase-3/7. In addition, the activation of p38 mitogen-activated protein kinase (MAPK) and c-Jun NH2-terminal kinase (JNK) was a critical mediator in RHL-induced growth inhibition. Inhibition of the expression of p38 MAPK and JNK by pharmacological inhibitors reversed RHL-induced growth inhibition by decreasing the level of cleaved PARP and caspase-3/7. Phosphorylation of the extracellular signal-related kinase (ERK) was increased by RHL; conversely, the MEK inhibitor which inhibits ERK activity, synergistically enhanced RHL-induced growth inhibition in HeLa cells. The results showed that RHL inhibits Hela cell growth through the activation of p38 MAPK and JNK, and is a potential chemotherapeutic agent for cervical cancer.

Rhein lysinate suppresses the growth of tumor cells and increases the anti-tumor activity of Taxol in mice.

In previous studies, rhein, one of the major bioactive constituents in the rhizome of rhubarb, inhibited the proliferation of various human cancer cells. However, because of its water insolubility, the anti-tumor efficacy of rhein was limited in vivo. In this study, we observed the anti-tumor activity of rhein lysinate (the salt of rhein and lysine easily dissolves in water) in vivo and investigated its mechanism. Inhibition of ovarian cancer SKOV-3 cell proliferation was determined by MTT assay and the mechanism of action of rhein lysinate was investigated by Western blot analysis. The therapeutic efficacy of rhein lysinate was evaluated by intragastric and intraperitoneal administrations in H22 hepatocellular carcinoma mice. Rhein lysinate inhibited the proliferation of SKOV-3 cells and the IC50 value was 80 microM. Rhein lysinate inhibited the phosphorylation of MEK and ERK and increased the anti-tumor activity of Taxol in vitro. It inhibited tumor growth by both intragastric and intraperitoneal administrations and improved the therapeutic effect of Taxol in H22 hepatocellular carcinoma mice. In conclusion, rhein lysinate offers an anti-tumor activity in vivo and is hopeful to be a chemotherapeutic drug.

Lidamycin shows highly potent cytotoxic to myeloma cells and inhibits tumor growth in mice.

AIM: To investigate the effects of lidamycin (LDM) on a mouse myeloma cell line (SP2/0) and human multiple myeloma cell lines (U266 and SKO-007), and provide the basis for the use of LDM in cancer therapy. METHODS: A 3-[4,5-dimethylthiazol-2-yl]5-[3-carboxymethoxyphenyl]-2-[4-sulfophenyl]2H-tetrazolium inner salt (MTS) assay was used to determine the degree of growth inhibition by the drugs analyzed in this study. Cell cycle distribution and analysis were measured by flow cytometry combined with propidium iodide (PI) staining. The effects on apoptosis were measured by Hoechst 33342 staining and by flow cytometry combined with fluorescein-isothiocyanate-Annexin V/propidium iodide (FITC-Annexin V/PI) staining. Protein expression was determined by Western blot analysis. In vivo antitumor activity was measured using a murine myeloma model in BALB/c mice. RESULTS: There was a significant reduction in cell proliferation after treatment with LDM. The overall growth inhibition correlated with increased apoptotic cell death. LDM-induced cell apoptosis was associated with the activation of c-Jun-N-terminal kinase (JNK), and cleavage of caspase-3/7 and poly (ADP-ribose) polymerase (PARP). LDM markedly suppressed tumor growth in a murine myeloma model. CONCLUSION: LDM induces apoptosis in murine myeloma SP2/0 cells as well as in human myeloma U266 and SKO-007 cell lines. The sustained activation of JNK might play a critical role in LDM-induced apoptosis in the SP2/0 cell line. LDM demonstrates significant antitumor efficacy against myeloma SP2/0 cells in mice. Taken together, our data provide some clues for further research of the effects of LDM on human multiple myeloma.Acta Pharmacologica Sinica (2009) 30: 1025-1032; doi: 10.1038/aps.2009.75.

Enediyne lidamycin induces apoptosis in human multiple myeloma cells through activation of p38 mitogen-activated protein kinase and c-Jun NH2-terminal kinase.

In the present study, the effects of lidamycin (LDM), a member of the enediyne antibiotic family, on two human multiple myeloma (MM) cell lines, U266 and SKO-007, were evaluated. In MTS assay, LDM showed much more potent cytotoxicity than conventional anti-MM agents to both cell lines. The IC(50) values of LDM for the U266 and SKO-007 cells were 0.0575 +/- 0.0015 and 0.1585 +/- 0.0166 nM, respectively, much lower than those of adriamycin, dexamethasone, and vincristine. Mechanistically, LDM triggered MM cells apoptosis by increasing the levels of cleaved poly ADP-ribose polymerase (PARP) and caspase-3/7. In addition, activation of p38 mitogen-activated protein kinase (MAPK) and c-Jun NH2-terminal kinase (JNK) was a critical mediator in LDM-induced cell death. Inhibition of the expression of p38 MAPK and JNK by pharmacological inhibitors reversed the LDM-induced apoptosis through decreasing the level of cleaved PARP and caspase-3/7. Interestingly, phosphorylation of extracellular signal-related kinase was increased by LDM; conversely, MEK inhibitor synergistically enhanced LDM-induced cytotoxicity and apoptosis in MM cells. The results demonstrated that LDM suppresses MM cell growth through the activation of p38 MAPK and JNK, with the potential to be developed as a chemotherapeutic agent for MM.