The Anticancer Effect of a Novel Quinoline Derivative 91b1 through Downregulation of Lumican

Quinoline derivatives have been reported to possess a wide range of pharmaceutical activities. Our group previously synthesized a series of quinoline compounds, in which compound 91b1 showed a significant anticancer effect. The purpose of this study was to evaluate the anticancer activity of compound 91b1 in vitro and in vivo, and screen out its regulated target. A series of cancer cell lines and nontumor cell lines were treated with compound 91b1 by MTS cytotoxicity assay and cell-cycle assay. In vivo anticancer activity was evaluated by a xenografted model on nude mice. Target prediction of 91b1 was assessed by microarray assay and confirmed by pancancer analysis. Relative expression of the target gene Lumican was measured by qRT-PCR. 91b1 significantly reduced tumor size in the nude mice xenograft model. Lumican was downregulated after 91b1 treatment. Lumican was proven to increase tumorigenesis in vivo, as well as cancer cell migration, invasion, and proliferation in vitro. The results of this study suggest that the anticancer activity of compound 91b1 probably works through downregulating the gene Lumican.

Expression of Insulin-Like Growth Factor Binding Protein-5 (IGFBP5) Reverses Cisplatin-Resistance in Esophageal Carcinoma

Cisplatin (CDDP) is one of the front-line chemotherapeutic drugs used in the treatment of esophageal squamous cell carcinoma (ESCC). Occurrence of resistance to CDDP has become one of the main challenges in cancer therapy. In this study, the gene expression profile of CDDP-resistant ESCC cells was investigated and molecular approaches were explored in an attempt to reverse the CDDP resistance. A CDDP-resistant SLMT-1/CDDP1R cell line was established from SLMT-1 cells by subculturing in the medium containing an increasing concentration of CDDP (0.1–1μg/mL). Mitochondrial (MTS) cytotoxicity assay, cell proliferation assay and cell morphology were used to assess the acquisition of cisplatin-resistance. The most differentially expressed gene in SLMT-1/CDDP1R cells was identified by cDNA microarray analysis compared with the parental SLMT-1 cells and validated by quantitative real-time polymerase chain reaction (qPCR). Association between expression of the most differentially expressed target gene to cisplatin-resistance was verified by RNA interference. An attempt to reversecisplatin-resistance phenotypes was made by using the vector expressing the most downregulated target gene in the CDDP-resistant cells. A CDDP-resistant ESCC cell line, SLMT-1/CDDP1R, was established with 2.8-fold increase CDDP-resistance (MTS₅₀ = 25.8 μg/mL) compared with the parental SLMT-1 cells. cDNA microarray analysis revealed that IGFBP5 showed the highest level of downregulation in SLMT-1/CDDP1R cells compared with the parental SLMT-1 cells. Suppression of IGFBP5 mediated by IGFBP5-targeting siRNA in parental SLMT-1 cells confirmed that IGFBP5 suppression in ESCC cells would induce CDDP-resistance. More importantly, upregulation of IGFBP5 using IGFBP5 expression vector reduced cisplatin-resistance in SLMT-1/CDDP1R cells by 41%. Thus, our results demonstrated that IGFBP5 suppression is one of the mechanisms for the acquisition of cisplatin-resistance in ESCC cells. Cisplatin-resistance phenotype can be reversed by increasing the expression level of IGFBP5. The overall findings of this study thus offered a new direction for reversing the CDDP resistance in ESCC and possibly in other cancer types with further investigations in future.

Anti-cancer Effects of a Novel Quinoline Derivative 83b1 on Human Esophageal Squamous Cell Carcinoma through Down-Regulation of COX-2 mRNA and PGE2

PURPOSE

83b1 is a novel quinoline derivative that has been shown to inhibit cancer growth in human esophageal squamous cell carcinoma (ESCC). This study was conducted to comprehensively evaluate the cytotoxic effects of 83b1 on a series of ESCC cell lines and investigate the mechanisms by which 83b1 suppresses cancer growth based on molecular docking analysis.

MATERIALS AND METHODS

A series of ESCC and nontumor immortalized cell lines were exposed to 83b1 and cisplatin (CDDP) in a dose-dependent manner, and the cytotoxicity was examined by a MTS assay kit. Prediction of the molecular targets of 83b1 was conducted by molecular docking analysis. Expression of cyclooxygenase 2 (COX-2) mRNA and COX-2-derived prostaglandin E₂ (PGE₂) were measured by quantitative real-time polymerase chain reaction and enzymelinked immuno-sorbent assay, respectively. In vivo anti-tumor effect was determined using a nude mice xenografted model transplanted with an ESCC cell line, KYSE-450.

RESULTS

83b1 showed the significant anti-cancer effects on all ESCC cell lines compared to CDDP; however, 83b1 revealed much lower toxic effects on non-tumor cell lines than CDDP. The predicted molecular target of 83b1 is peroxisome proliferator-activated receptor delta (PPARδ), which is a widely known oncoprotein. Additionally the expression of COX-2 mRNA and COX-2-derived PGE₂ were down-regulated by 83b1 in a dose-dependent manner in ESCC cell lines. Furthermore, 83b1 was shown to significantly reduce the tumor size in nude mice xenograft.

CONCLUSION

The results of this study suggest that the potential anti-cancer effects of 83b1 on human esophageal cancers occur through the possible oncotarget, PPARδ, and down-regulation of the cancer related genes and molecules.

Synthesis of 8-hydroxyquinoline derivatives as novel antitumor agents

This letter describes the preparation of quinoline derivatives and their cytotoxic potentials toward human carcinoma cell lines. Among the selected compounds, 8-hydroxy-2-quinolinecarbaldehyde (3) showed the best in vitro cytotoxicity against the human cancer cell lines, including MDA231, T-47D, Hs578t, SaoS2, K562, SKHep1 (with a MTS50 range of 12.5-25 μg/mL) and Hep3B (with a MTS50 range of 6.25±0.034 μg/mL). The in vivo antitumor activity of compound 3 on subcutenaous Hep3B hepatocellular carcinoma xenograft in athymic nude mice was then studied. The results showed that the dose of 10 mg/kg/day of compound 3 with intraperitoneal injection for 9 days totally abolished the growth of the xenograft tumor of Hep3B with no histological damage on vital organs as compared with the control. The experimental results suggested that compound 3 has a good potential as an antitumor agent.

Extracellular protease ADAMTS9 suppresses esophageal and nasopharyngeal carcinoma tumor formation by inhibiting angiogenesis

ADAMTS metalloprotease family member ADAMTS9 maps to 3p14.2 and shows significant associations with the aerodigestive tract cancers esophageal squamous cell carcinoma (ESCC) and nasopharyngeal carcinoma (NPC). However, the functional impact of ADAMTS9 on cancer development has not been explored. In this study, we evaluated the hypothesized antiangiogenic and tumor-suppressive functions of ADAMTS9 in ESCC and NPC, in stringent tumorigenicity and Matrigel plug angiogenesis assays. ADAMTS9 activation suppressed tumor formation in nude mice. Conversely, knockdown of ADAMTS9 resulted in clones reverting to the tumorigenic phenotype of parental cells. In vivo angiogenesis assays revealed a reduction in microvessel numbers in gel plugs injected with tumor-suppressive cell transfectants. Similarly, conditioned medium from cell transfectants dramatically reduced the tube-forming capacity of human umbilical vein endothelial cells. These activities were associated with a reduction in expression levels of the proangiogenic factors MMP9 and VEGFA, which were consistently reduced in ADAMTS9 transfectants derived from both cancers. Taken together, our results indicate that ADAMTS9 contributes an important function in the tumor microenvironment that acts to inhibit angiogenesis and tumor growth in both ESCC and NPC.

Phyllanthus urinaria extract attenuates acetaminophen induced hepatotoxicity: involvement of cytochrome P450 CYP2E1

Acetaminophen is a commonly used drug for the treatment of patients with common cold and influenza. However, an overdose of acetaminophen may be fatal. In this study we investigated whether mice, administered intraperitoneally with a lethal dose of acetaminophen, when followed by oral administration of Phyllanthus urinaria extract, may be prevented from death. Histopathological analysis of mouse liver sections showed that Phyllanthus urinaria extract may protect the hepatocytes from acetaminophen-induced necrosis. Therapeutic dose of Phyllanthus urinaria extract did not show any toxicological phenomenon on mice. Immunohistochemical staining with the cytochrome P450 CYP2E1 antibody revealed that Phyllanthus urinaria extract reduced the cytochrome P450 CYP2E1 protein level in mice pre-treated with a lethal dose of acetaminophen. Phyllanthus urinaria extract also inhibited the cytochrome P450 CYP2E1 enzymatic activity in vitro. Heavy metals, including arsenic, cadmium, mercury and lead, as well as herbicide residues were not found above their detection limits. High performance liquid chromatography identified corilagin and gallic acid as the major components of the Phyllanthus urinaria extract. We conclude that Phyllanthus urinaria extract is effective in attenuating the acetaminophen induced hepatotoxicity, and inhibition of cytochrome P450 CYP2E1 enzyme may be an important factor for its therapeutic mechanism.

The inhibitory effect of Gleditsia sinensis on cyclooxygenase-2 expression in human esophageal squamous cell carcinoma

The anti-cancer effects of the anomalous fruit extract of Gleditsia sinensis (GSE) attributed to its apoptotic activity, telomerase inhibition and anti-angiogenesis in a panel of solid and non-solid tumor cell lines including esophageal squamous cell carcinoma (ESCC) have been intensively investigated by us in previous studies. Cyclooxygenase-2 (COX-2) has been well described as another promising target of cancer therapy for ESCC, and novel therapeutic agents are still being sought which target COX-2 expression. However, the anti-cancer effect of GSE through the suppression of COX-2 expression has not been previously investigated. In the present study, the anti-cancer effects of GSE on eight ESCC cell lines (KYSE 30, KYSE 150, KYSE 450, KYSE 510, KYSE 520, HKESC-3, HKESC-4 and SLMT-1) of Chinese and Japanese origins were first studied by MTS cytotoxicity assays. The effects of GSE on COX-2 expression levels and on the housekeeping form COX-1 were also investigated by multiplex RT-PCR analysis. Moreover, the anti-proliferative effect of GSE on KYSE 510 was also studied by anchorage-independent clonogenicity assay in soft agar. The results showed that GSE induced a dose- and time-dependent cytotoxicity on all of the eight ESCC cell lines and caused positive anti-proliferative action on KYSE 510 in the anchorage-independent clonogenicity assay, suggesting that GSE suppressed the in vitro growth of the ESCC cell lines. More importantly, the MRNA expression levels of COX-2, but not COX-1, in all of the ESCC cell lines were suppressed by GSE in a dose-dependent fashion. The overall results of the present study show that the anti-cancer effect of GSE on the ESCC cell lines is associated with the suppression of COX-2 expression, but not COX-1. Our findings also open a new chapter for the future advancement of GSE as a novel anti-cancer agent or as an adjuvant of traditional cancer treatments.

In vitro cytotoxicity of (-)-EGCG octaacetate on MDAMB-231 and SKHep-1 human carcinoma cells: a pharmacological consideration on prodrug design

Esterification of acetate with generic pharmaceutical compound has been commonly employed to produce ester prodrug for improving its potency when compared with the mother compound. Acetate, on the other hand, has been recognized to have inhibitory effect on the respiratory biochemistry. Here we demonstrate that acetate at a concentration of 400 microM exhibited significant growth inhibitory activity on two human cancer cell lines, the MDAMB-231 breast cancer and the SKHep-1 hepatoma cell lines. To establish the ester prodrug with multi-acetate ester conjugates as our experimental model, one molecule of (-)-epigallocatechin gallate was required to conjugate with eight molecules of acetate forming the corresponding (-)-epigallocatechin gallate octaacetate prodrug. Chemical structure of this epigallocatechin gallate octaacetate ester prodrug was confirmed by both 13C and 1H nuclear magnetic resonance spectra and mass spectrometry. Further cytotoxic assay using both MDAMB-231 and SKHep-1 human carcinoma cell lines showed that acetate at a concentration of 400 microM exhibits an additional cytotoxic effect with (-)-epigallocatechin gallate at a concentration of 50 microM, although the additional effect was not as high as (-)-epigallocatechin gallate octaacetate ester prodrug alone at a concentration of 50 microM. Our results thus raise a pharmacological consideration of using multi-acetate conjugate as the ester prodrug where the release of free acetate by esterase could be part of the explanation for the improved in vitro cytotoxicity.

Paradoxical proliferative potential of iron (II) sulphate on cancer cells after the 3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium (MTS) assay

There are several scientific approaches for the determination of cellular growth influences of known or novel substances under in vitro conditions, among which colourimetric absorption measurement is considered to be one of the convenient methods. [3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium] (MTS) assay is one of the commonly used colourimetric absorption assays based on the ability of dehydrogenase from viable cells to produce the brown soluble formazan detectable at 490 nm. Here we have tested the possible growth influence of iron (II) sulphate on two human cancer cell lines, the K562 chronic myelogenous leukaemia and T47D breast carcinoma cells, based on the MTS assay. We found that iron (II) sulphate possessed an inhibitory effect when added at 16- to 125-microM concentrations, but iron (II) sulphate became growth stimulatory when its concentration was further increased to 1000 microM. In addition, a dose-dependent increase in absorbance at the same wavelength was observed when we repeated the experiments without the addition of MTS and phenazine methosulfate. When we further repeated the cell growth determinations using adenosine triphosphate content assay for K562 and 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay for T47D, iron (II) sulphate showed a consistent dose-dependent growth inhibitory effect. Morphological investigation after methylene blue staining clearly demonstrated that iron (II) sulphate, at a concentration of 1000 microM, is cytotoxic to T47D cells. Interestingly, a consistent increment for the absorbance at 490 nm was further observed with increased iron (II) sulphate concentration either in the presence or absence of MTS even in a cell-free environment. Thus we conclude that iron (II) sulphate is actually growth inhibitory and even cytotoxic at high concentrations towards the K562 and T47D cancer cells and the paradoxical proliferative activity of iron (II) sulphate on these two cancer cell lines using the MTS assay was solely due to the oxidation of initial pale green iron (II) to brownish iron (III) during incubation in the aqueous condition.

Mechanistic insight into a novel synthetic cantharidin analogue in a leukaemia model

Cantharidin isolated from Mylabris caraganae and other insects is used traditionally as an anti-cancer drug especially on hepatoma and leukaemia. Previously, we demonstrated that the novel synthetic cantharidin analogue CAN 032 possessed apoptotic activity on two human hepatoma cell lines Hep3B hepatocellular carcinoma and SK-Hep-1 liver adenocarcinoma. However, its underlying mechanistic action on cancer cells remained unclear. Herein, we furthered our work by making use of KG1a acute myelogenous leukaemia (AML) and K562 chronic myelogenous leukaemia (CML) as experimental models. As anticipated, both leukaemia cell lines were sensitive to the cytotoxic action of CAN 032. The activity of CAN 032 was both dose- and time-course-dependent. CAN 032 readily inhibited the colony formation potential of both leukaemia cell lines. KG1a AML treated with CAN032 decreased G1 phase cell population, mitochondrial membrane potential collapse, caspase 3 activation and hence DNA fragmentation. Pre-incubation of leukaemia cells with the general caspase inhibitor Z-VAD-FMK could partially reversed the apoptotic action of CAN 032. This result suggested that the caspase- dependent pathway is necessary for the apoptotic action of CAN 032. CAN 032 provides a new direction for novel drug discovery in experimental cancer therapy.

Apoptogenic activity of a synthetic cantharimide in leukaemia: implication on its structural activity relationship

Cantharidin isolated from Mylabris caraganae and other insects has been used as an anti-cancer drug in China for many years. However, its toxicity on the renal system and suppression effect on bone marrow limits its usage clinically. A synthetic analogue of cantharidin (CAN 037) has been shown to have cytotoxic effect on the SK-Hep 1 hepatoma cell line but its underlying working principle remains undefined. Here we further report the action of CAN 037 on an acute myelogenous leukaemia (AML) cell line, KG1a. [3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium] (MTS) assay was used to demonstrate the cytotoxicity of CAN 037 on KG1a cells. Morphological changes of CAN 037-treated leukaemia cells were recorded under an inverted microscope. Possible activation of caspase 3, 8 and 9 from KG1a cells was also investigated. KG1a AML cells were sensitive to CAN 037. Morphological changes including cell shrinkage and loss of colony formation ability were observed. Caspase 3, 8 and 9 activity was elevated, whereas pre-incubating the KG1a cells with the generic caspase inhibitor z-VAD-fmk could only partially reverse the CAN 037-induced cell death. In addition to the SK-Hep-1 hepatoma cell line, CAN 037 is also effective in inducing the death of KG1a AML cells in vitro. Apoptosis is involved in the action of CAN 037 including the activation of the caspase family. Caspase-dependent cell death pathway may be necessary but not essential in CAN 037-induced apoptosis of KG1a cells. Further consideration of the structural activity relationship of CAN 037 may provide opportunities to improve its therapeutic value.

Synthesis and structure evaluation of a novel cantharimide and its cytotoxicity on SK-Hep-1 hepatoma cells

A remarkable control of the potency of cantharimide is described based on the electronic properties of functional group and it exhibits a relatively less toxic effect to the non-malignant hematological disorder bone marrow cells.

Antiproliferative ability of a combination regimen of crocodile egg extract, wild radix ginseng and natural Ganoderma lucidum on acute myelogenous leukemia

Chinese practitioners have employed the use of traditional Chinese medicine as an anti-cancer agent since the ancient period. Different combinations have been formulated for various purposes. Some have been claimed for post-chemotherapy use but their direct actions on cancer cells may not be significantly reported. In the present study, we have tested the possible anti-leukemia potential of a combination regimen including crocodile egg extract, wild radix ginseng and natural Ganoderma lucidum (CGG extract) on acute myelogenous leukemia (AML) in vitro. A water soluble CGG extract was prepared and its antiproliferative activity was tested on the KG1a AML cell line and two freshly prepared bone marrow aspirate samples isolated from patients with de novo AML during presentation by a MTS/PMS assay. Furthermore, the possible activity of the CGG extract on the regeneration potential of KG1a cells was also investigated using a semi-solid methyl-cellulose colony formation assay. Lastly, the acute toxicity of CGG extract was further examined by a single high-dose oral feeding to rats. We found that the CGG extract could possess significant antiproliferative activity on AML cells. A strong colony formation inhibition was further demonstrated on KG1a cells. After feeding the rats with an excessive dose of CGG extract, we observed no development of acute toxicity. We concluded that the CGG extract has growth inhibitory potential on KG1a cells and AML bone marrow samples in vitro. An in vivo toxicity test revealed that no acute toxicity was observed after feeding the rats a high dosage of the CGG extract. Further animal model tests are necessary to investigate the possible chronic toxicity of the CGG extract.

Apoptogenic activity of a synthetic cantharimide in leukaemia: implication on its structural activity relationship

Cantharidin isolated from Mylabris caraganae and other insects has been used as an anti-cancer drug in China for many years. However, its toxicity on the renal system and suppression effect on bone marrow limits its usage clinically. A synthetic analogue of cantharidin (CAN 037) has been shown to have cytotoxic effect on the SK-Hep 1 hepatoma cell line but its underlying working principle remains undefined. Here we further report the action of CAN 037 on an acute myelogenous leukaemia (AML) cell line, KG1a. [3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium] (MTS) assay was used to demonstrate the cytotoxicity of CAN 037 on KG1a cells. Morphological changes of CAN 037-treated leukaemia cells were recorded under an inverted microscope. Possible activation of caspase 3, 8 and 9 from KG1a cells was also investigated. KG1a AML cells were sensitive to CAN 037. Morphological changes including cell shrinkage and loss of colony formation ability were observed. Caspase 3, 8 and 9 activity was elevated, whereas pre-incubating the KG1a cells with the generic caspase inhibitor z-VAD-fmk could only partially reverse the CAN 037-induced cell death. In addition to the SK-Hep-1 hepatoma cell line, CAN 037 is also effective in inducing the death of KG1a AML cells in vitro. Apoptosis is involved in the action of CAN 037 including the activation of the caspase family. Caspase-dependent cell death pathway may be necessary but not essential in CAN 037-induced apoptosis of KG1a cells. Further consideration of the structural activity relationship of CAN 037 may provide opportunities to improve its therapeutic value.

Antiangiogenic activity of a concentrated effective microorganism fermentation extract

We have previously demonstrated the possible growth inhibitory activity of both first generation of the effective microorganism fermentation extract (EM-X) as well as the second generation (EM-X2) on cancer cell lines in vitro. The possible anti-angiogenic potential of EM-X has not been reported. Herein we show that using the concentrated EM-X, the growth of human umbilical cord endothelial cells (HUCE) was significantly inhibited in vitro. Enzyme linked immunosorbent assay suggested that the concentrated EM-X is able to reduce the level of vascular endothelial growth factor (VEGF) from Hep3B hepatocellular carcinoma (HCC) cells. The conditioned culture medium obtained from the concentrated EM-X incubated Hep3B HCC cells possessed significant antiproliferative effect on the HUCE cells. Moreover, in vivo chick chorioallantoic membrane assay further demonstrated that the concentrated EM-X is able to greatly inhibit the basic fibroblast growth factor induced angiogenesis from chick embryo experiment. We speculate that the anti-cancer potential of this concentrated EM-X involved growth inhibition on cancer cell and antiangiogenic effect on HUCE cells.

Mechanistic insight into a novel synthetic cantharidin analogue in a leukaemia model

Cantharidin isolated from Mylabris caraganae and other insects is used traditionally as an anti-cancer drug especially on hepatoma and leukaemia. Previously, we demonstrated that the novel synthetic cantharidin analogue CAN 032 possessed apoptotic activity on two human hepatoma cell lines Hep3B hepatocellular carcinoma and SK-Hep-1 liver adenocarcinoma. However, its underlying mechanistic action on cancer cells remained unclear. Herein, we furthered our work by making use of KG1a acute myelogenous leukaemia (AML) and K562 chronic myelogenous leukaemia (CML) as experimental models. As anticipated, both leukaemia cell lines were sensitive to the cytotoxic action of CAN 032. The activity of CAN 032 was both dose- and time-course-dependent. CAN 032 readily inhibited the colony formation potential of both leukaemia cell lines. KG1a AML treated with CAN032 decreased G1 phase cell population, mitochondrial membrane potential collapse, caspase 3 activation and hence DNA fragmentation. Pre-incubation of leukaemia cells with the general caspase inhibitor Z-VAD-FMK could partially reversed the apoptotic action of CAN 032. This result suggested that the caspase- dependent pathway is necessary for the apoptotic action of CAN 032. CAN 032 provides a new direction for novel drug discovery in experimental cancer therapy.

Identification of a tumor suppressive critical region mapping to 3p14.2 in esophageal squamous cell carcinoma and studies of a candidate tumor suppressor gene, ADAMTS9

A gene critical to esophageal cancer has been identified. Functional studies using microcell-mediated chromosome transfer of intact and truncated donor chromosomes 3 into an esophageal cancer cell line and nude mouse tumorigenicity assays were used to identify a 1.61 Mb tumor suppressive critical region (CR) mapping to chromosome 3p14.2. This CR is bounded by D3S1600 and D3S1285 microsatellite markers. One candidate tumor suppressor gene, ADAMTS9, maps to this CR. Further studies showed normal expression levels of this gene in tumor-suppressed microcell hybrids, levels that were much higher than observed in the recipient cells. Complete loss or downregulation of ADAMTS9 gene expression was found in 15 out of 16 esophageal carcinoma cell lines. Promoter hypermethylation was detected in the cell lines that do not express this gene. Re-expression of ADAMTS9 was observed after demethylation drug treatment, confirming that hypermethylation is involved in gene downregulation. Downregulation of ADAMTS9 was also found in 43.5 and 47.6% of primary esophageal tumor tissues from Hong Kong and from the high-risk region of Henan, respectively. Thus, this study identifies and provides functional evidence for a CR associated with tumor suppression on 3p14.2 and provides the first evidence that ADAMTS9, mapping to this region, may contribute to esophageal cancer development.

Apoptotic activity of a novel synthetic cantharidin analogue on hepatoma cell lines

Cantharidin isolated from Mylabris caraganae and other insects is used traditionally as an anti-cancer drug. However, its toxicity on the renal system and suppression effect on bone marrow limits its clinical usage. Recently, we have synthesized two cantharidin analogues, CAN 029 (compound 2) and CAN 030 (compound 3). Although both showed an apoptotic induction ability on cancer cells, they were still relatively toxic towards non-malignant haematological disordered bone marrow. Based on the principle structure of cantharidin, we have further chemically synthesized another analogue, CAN 032. The cytotoxic activity of this analogue was screened on both Hep3B hepatocellular carcinoma and SK-Hep-1 liver adenocarcinoma cell lines by [3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium] (MTS) assay. Morphological changes of hepatoma cell lines were recorded under an inverted microscope. The possible tolerance of these analogues was further investigated using non-malignant haematological bone marrow primary culture. CAN 032 showed a significant cytotoxic response on both hepatoma cell lines in which the potencies were comparable to that of cantharidin. Further screening on the bone marrow tolerance revealed that compound CAN 032 showed a relatively less toxic effect. Phase contrast microscopy demonstrated that cell shrinkage, rounding, loss of adherent property and loss of colony-formation ability were induced. The dose-dependence of the response of CAN 032 on Hep3B was further assayed by DNA fragmentation gel electrophoresis. The G1 peak of Hep3B cells was reduced. Chemically synthesized CAN 032 may provide an improved therapeutic advantage over traditional cantharidin.

In vitro anti-cancer activity of a novel microbial fermentation product on human carcinomas

The possible anti-proliferation and cell death induction potential of a novel microbial fermentation extract named as oncogen XP-180 (or simply as XP-180) was tested on three human solid tumour carcinoma cell lines (non-small cell lung cancer A549, breast cancer MDA-MB231, liver adenocarcinoma SK-Hep1) and on the acute myelogenous leukaemia KG1a cell line. Anti-proliferative activity of XP-180 was observed on all of these cancer cell lines with comparable efficiency and in a dose-dependent manner. Morphological investigation further suggested that common features of apoptosis, including cell shrinkage and rounding, are present in XP-180 treated cells. Loss of adhesion properties of these solid tumour cell lines was observed upon XP-180 incubation. Anchorage-dependent clonogenicity assay on solid tumour cell lines and semi-solid methylcellulose colony formation assay on leukaemia cell line further revealed that XP-180 strongly inhibited the regeneration potential of these cancer cells. Using KG1a as an experimental model system, XP-180 was shown to stimulate the activity of caspase 3, 8 and 9 without significant change in caspase 6 activity. Furthermore, XP-180 readily induced collapse of mitochondrial membrane potential after 2 h of incubation. However, the use of the generic caspase specific inhibitor Z-VAD-FMK does not significantly reverse XP-180 mediated cell death. The results obtained suggest that XP-180-mediated cancer cell death could involve mitochondria and both caspase-dependent and -independent pathways. Therefore, XP-180 is an efficient anti-cancer regimen in vitro.

Apoptotic potential of the concentrated effective microorganism fermentation extract on human cancer cells

The effective microorganism fermentation extract (EM-X, the first generation) was claimed to possess strong anti-oxidation property. On the other hand, we have shown that the second generation of the effective microorganism fermentation extract (EM-X2) possessed growth inhibition on human cancer cells involving MDA-MB231 breast cancer and K-562 chronic myelogenous leukaemia cells. Elevation of super oxide dismutase activity from EM-X2 treated cancer cell extract was observed. However, the possible anti-cancer activity of the first generation of the EM-X was not reported. Here we demonstrate that the concentrated form of the EM-X from its original fluid also possess antiproliferation ability together with induction of apoptosis on the human cancer cell lines including Hep3B hepatocellular carcinoma (HCC) and KG1a acute myelogenous leukaemia (AML). Similar effect could also be demonstrated on primary cultured bone marrow samples isolated from patients with AML. Morphological inspection revealed that common apoptotic feature was found on these concentrated EM-X treated cancer cells. Both the anchorage-dependent clonogenicity assay on Hep3B HCC and methyl-cellulose colony formation assay on KG1a cells and bone marrow cells from AML patients further revealed the ability of the concentrated EM-X on reducing their colony formation ability. Incubating KG1a with concentrated EM-X readily induced apoptosis as demonstrated by flow cytometric analysis. Interestingly, few growth inhibition effect of the concentrated EM-X was observed on both the SV40 transformed THLE-2 liver epithelial cells and primary cultured non-malignant haematological disordered bone marrow. Collectively, this concentrated EM-X is effective in inducing cell death and reducing the regeneration potential of both Hep3B HCC and KG1a AML cells in vitro.

Induction of apoptosis on carcinoma cells by two synthetic cantharidin analogues

Cantharidin isolated from Mylabris caraganae and other insects has been used as an anti-cancer drug in China for many years. However, its toxicity on the renal system and suppression effect on bone marrow limits its usage clinically. Based on the core structure of cantharidin, we have chemically synthesized two cantharidin analogues (compounds 2 and 3). The cytotoxic activity of these analogues was demonstrated on the Hep3B hepatocellular carcinoma, MDA-MB231 breast cancer, A549 non-small cell lung carcinoma and KG1a acute myelogenous leukaemia (AML) cell lines by monitoring the intracellular adenosine triphosphate level. Morphological changes in these cancer cell lines, including cell shrinkage and loss of adherent potential, were readily observed. By making use of the KG1a AML cells as a test model, we further found that mitochondrial membrane potential depolarization and reduction of intracellular bcl-2 anti-apoptotic protein level were involved. These resulted in the activation of caspase 3 protease activity and oligonucleosomal length DNA fragment formation as detected by both time resolved fluorescence technology-based caspase activity assay and TdT-mediated dUTP nick end-labelling assay.

Antiproliferative and apoptosis-inducing activity of Brucea javanica extract on human carcinoma cells

We have recently demonstrated the antiproliferative and apoptotic activities of herbal traditional Chinese medicines, including the analomous fruit extract of Gleditsia sinensis, the fresh juice of Scutellaria barbata and the warmed water extract of Radix Sophorae Tonkinensis on a series of human carcinoma cells. Here, we further report the potential anti-cancer activity of the warmed water extract of Brucea javanica (BJE). Four cancer cell lines, including A549 non-small cell lung cancer, Hep3B hepatocellular carcinoma, MDA-MB231 breast cancer and SLMT-1 oesophageal squamous cell carcinoma, were incubated with BJE and strong apoptotic induction was observed under inverted microscopic investigation for all of the four cell lines tested. Using the MDA-MB231 breast cancer cell line as an experimental model, additional analyses supported the hypothesis that the mitochondrial membrane potential depolarization pathway was induced by BJE. The APO-1/Fas receptor death induction pathway was not activated under the influence of BJE, as studied by staining with Fas ligand and Fas receptor specific antibodies. Accordingly, only weak activation of caspase 8 was observed upon BJE treatment. On the other hand, caspase 3 activity was stimulated up to five-fold in BJE-treated cells compared to untreated controls. Oligonucleosomal DNA fragmentation formation was detected by labelling the nucleic acid ladders with TdT-mediated dUTP nick end labelling. Collectively, BJE-induced cancer cell death proceeds through a mitochondrial dependent pathway associated with caspase 3 activation.

Inhibition of proteasome activity in Gleditsia sinensis fruit extract-mediated apoptosis on human carcinoma cells

The anomalous fruit extract of Gleditsia sinensis (GSE) was shown to possess anticancer potential on various solid tumour and leukaemia cell lines in vitro. We have recently demonstrated that the mitochondrial-dependent apoptotic pathway including mitochondrial membrane potential depolarization, changes in the level of reactive oxygen species and activation of caspase 3 were recruited in GSE-induced apoptosis. Whether receptor-dependent APO-1/Fas apoptotic pathway is also involved remains uncertain. Using two solid tumour cell lines, the HepG2 hepatoblastoma carcinoma cells and MDA-MB231 breast cancer cells, we demonstrated that the Fas ligand and Fas receptor protein levels did not have significant variation after GSE incubation. Caspase 8 activity increased only weakly when compared with that of caspase 3. The chrymotrypsin-like activity of proteasome was partially inhibited up to 30-40% when compared with the untreated control. Taken together, we believe that GSE- mediated apoptosis on HepG2 and MDA-MB231 carcinoma cells is mainly dictated by the mitochondrial-dependent pathway while inhibition of proteasome activity may also be involved in GSE-induced apoptosis.

Antiproliferation and induction of cell death of Phaffia rhodozyma (Xanthophyllomyces dendrorhous) extract fermented by brewer malt waste on breast cancer cells

Astaxanthin has been shown to have antiproliferative activity on breast cancer and skin cancer cells. However, the high cost of production, isolation and purification of purified astaxanthin from natural sources or chemically synthetic methods limit its usage on cancer therapy. We show that astaxanthin could be produced by fermentating the Phaffia rhodozyma (Xanthophyllomyces dendrorhous) yeast cells with brewer malt waste using a 20 L B. Braun fermentor. The percentage composition of astaxanthin from the P. rhodozyma was >70% of total pigment as estimated by the high performance liquid chromatographic analysis. Furthermore, the antiproliferative activity of this P. rhodozyma cell extract (PRE) was demonstrated on breast cancer cell lines including the MCF-7 (estrogen receptor positive) and MDA-MB231 (estrogen receptor negative) by using the [3-(4,5-dimethylthiazol-2-yl)-5-(3-arboxymethoxyphenyl)-2- (4-sulfophenyl)-2H-tetrazolium] (MTS) assay. No apoptotic cell death, but growth inhibitory effect was induced after 48 h of PRE incubation as suggested by morphological investigation. Anchorage-dependent clonogenicity assay showed that PRE could reduce the colony formation potential of both breast cancer cell lines. Cell death was observed from both breast cancer cell lines after incubation with PRE for 6 days. Taken together, our results showed that by using an economic method of brewer malt waste fermentation, we obtained P. rhodozyma with a high yield of astaxanthin and the corresponding PRE could have short-term growth inhibition and long-term cell death activity on breast cancer cells.

Activities of fresh juice of Scutellaria barbata and warmed water extract of Radix Sophorae Tonkinensis on anti-proliferation and apoptosis of human cancer cell lines

The possible antiproliferative and apoptotic inducing potentials of fresh juice prepared from Scutellaria barbata (SBJ) and warmed water extract of Radix Sophorae Tonkinensis (RSTE) have been tested on a series of cancer cell lines, including HepG2 hepatoblastoma, Hep3B hepatocellular carcinoma, MDA-MB231 breast carcinoma, A549 lung cancer and KG-1 acute myelogenous leukaemia in vitro. Both SBJ and RSTE were able to inhibit the growth of cancer cell lines and induce apoptosis. Further analysis of the action of RSTE on HepG2 cells suggested that the activity of the central machinery of apoptosis, caspase 3, was significantly elevated. Oligo-nucleosomal length DNA fragments formation was readily detected by TdT-mediated dUTP nick end labelling assay after RSTE treatment. Taken together, we believe that, although Radix Sophorae Tonkinensis was demonstrated to have toxic components including matrine and oxymatrine, it is still worthwhile to further investigate its anti-cancer potential under a safety toxicological precaution.

Gleditsia sinensis fruit extract-induced apoptosis involves changes of reactive oxygen species level, mitochondrial membrane depolarization and caspase 3 activation

Recently, we have shown that the anomalous fruit extract of Gleditsia sinensis (GSE) processes apoptotic activity on numerous solid tumour and leukaemia cell lines as well as primary cultured leukaemia cells obtained from bone marrow aspirate of patients. GSE treated cancer cells exhibited apoptotic features as readily illustrated by morphological investigation, DNA fragmentation analysis and TUNEL labelling methods. Elevation of intracellular superoxide dismutase activity was observed. However, the detailed mechanism still remains undefined. Here we further demonstrated that cell cycle arrest, increment of hydrogen peroxide production, changes of intracellular acid-base equilibrium and mitochondrial membrane potential depolarization (DeltaPsi(m)) were induced from cancer cells after GSE incubation. Caspase 3 protease activity was significantly enhanced upon GSE treatment. Taken together, a defined signaling pathway for the mechanistic action of GSE on cancer cells was worked out.

Growth inhibitory potential of effective microorganism fermentation extract (EM-X) on cancer cells

The effective microorganism (EM-X) fermentation extract is derived from rice bran and seaweed extract. It has been shown to possess anti-oxidation activity both in vitro and in vivo. To our knowledge, the possible in vitro anti-cancer potential of EM-X has not been demonstrated. Here we showed that the double concentrate of EM-X (EM-X2) at concentrations of 20-30% by volume, had growth inhibitory activity on MDA-MB231 breast cancer cell line and K-562 chronic myelogenous leukaemia cell lines by [3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2-H-tetrazolium, inner salt] (MTS) assay. No characteristic features of apoptosis could be observed morphologically. Colony formation assay illustrated that both MDA-MB231 breast cancer and K-562 CML cells lost part of their regeneration potential after treatment with EM-X2 at 30% concentration by volume for 24 h. At these concentrations, only slight growth inhibitory effect was observed in 293 human kidney fibroblast cells and in three non-malignant bone marrows. Intracellular nitro blue tetrazolium (NBT) reduction assay showed that both MDA-MB231 breast cancer and K-562 CML cells had about 30% reduction of intracellular NBT after incubation with 30% of EM-X2. Increased activity of superoxide dismutase (SOD) could be detected from both MDA-MB231 and K-562 cell lines after incubating with 30% of EM-X2. Taken together, our data suggested that EM-X could inhibit growth and reduce the regeneration potential of cancer cells, possibly through its antioxidation activity.

Superoxide anion is involved in the early apoptosis mediated by Gleditsia sinensis fruit extract

Changes in the intracellular level of reactive oxygen species (ROS) including superoxide anion, hydroxyl radical, hydrogen peroxide and finally cellular acid-base equilibrium are reported to play an important role in the early step of apoptosis. All of which would precede the loss of mitochondrial membrane potential and releasing of those apoptotic inducing factors such as cytochrome c as well as caspases activation. Any potential chemotherapeutic agent that could drive such changes in ROS would be particularly attractive. Recently we have reported the potential use of Gleditsia sinensis extract (GSE) in cancer therapy including solid tumour and leukaemia cell lines as well as primary cultured leukaemia cells in vitro. We demonstrated that apoptotic activity is involved. Here we further showed that the mechanism of GSE induced apoptosis, including an early decreasing of intracellular superoxide anion as measured by nitroblue tetrazolium (NBT) reduction assay. This phenomenon readily occurred before any shrinkage of cancer cells including MDA-MB231 breast cancer, CNE-2 nasopharyngeal carcinoma, K-562 chronic myelogenous leukaemia and KG1-a, acute myelogenous leukaemia. Cell viability was determined by morphological investigation and the [3-(4,5-dimethyl-thiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium] (MTS) assay. Furthermore, the superoxide dismutase activity from those cellular extracts after GSE treatment seemed to be increased. Taken together, we speculate that the GSE-induced apoptosis, via ROS pathway, involves an early decrease of intracellular superoxide anion.

Inactivation mechanisms and growth suppressive effects of p16INK4a in Asian esophageal squamous carcinoma cell lines

The inactivation mechanisms and functional role of p16INK4a in three Asian esophageal squamous cell carcinoma (ESCC) cell lines were investigated by polymerase chain reaction (PCR) amplification, DNA sequencing, methylation-specific PCR analysis, reverse transcription-PCR, Western blotting, and colony formation assays. The p16INK4a was inactivated by promoter hypermethylation in all three cell lines, a homozygous deletion of exons 2 and 3, and a frameshift deletion on exon 1, leading to transcriptional silencing or the production of mutant p16INK4a protein. Two ESCC cell lines transfected with wild type p16INK4a show significantly reduced cell growth properties. The results of the present studies support the suppressive role of p16INK4a in ESCC development.

Antiproliferative activity of the extract of Gleditsia sinensis fruit on human solid tumour cell lines

BACKGROUND

The fruit extract of Gleditsia sinensis Lam. (GSE) is a traditional herbal medicine that is saponin-rich. However, its activity on solid tumour cell lines has never been demonstrated.

METHODS

The activity of GSE was demonstrated in four cancer cell lines (breast cancer MCF-7, MDA-MB231, hepatoblastoma HepG2 and oesophageal squamous carcinoma cell line SLMT-1) using MTT assay, anchorage-independent clonogenicity assay, DNA laddering and in situ cell death detection.

RESULTS

The mean MTT(50) (the mean concentration of GSE to reduce MTT activity by 50%) ranged from 16 to 20 microg/ml of GSE. An anchorage-independent clonogenicity assay showed that all of the four solid tumour cell lines gradually lost their regeneration potential after treatment with GSE, DNA fragmentation and TUNEL analysis demonstrated that the action of GSE is both dose- and time course-dependent.

CONCLUSIONS

Our results suggest that GSE has a cytotoxic activity and can induce apoptosis in human solid tumour cell lines.

Gleditsia sinensis fruit extract induced growth inhibition involves basic fibroblast growth factor and nitric oxide

Recently we have shown the antiproliferative activity of Gleditsia sinensis fruit extract (GSE) on various solid tumour and leukaemia cell lines as well as primary cultured bone marrow cells isolated from patients with acute and chronic myelogenous leukaemia. We further studied whether the growth inhibitory effect of GSE involves basic fibroblast growth factor (bFGF) in cancer cell lines including breast cancer MDA-MB231, nasopharyngeal cancer CNE-2 and prostate cancer LNCaP. We also investigated whether GSE could alter the production of nitric oxide (NO) pattern from these cancer cell lines. Growth inhibition assay was quantitated by sulforhodamine B protein staining method. Enzyme linked immunosorbent assay (ELISA) was used to quantitate the total bFGF protein. The amount of NO secreted into culture medium in terms of nitrite ion concentration was measured by the Greiss method. ELISA showed that GSE could stimulate total bFGF protein level which was dose- dependent. NO production was also stimulated from these cancer cell lines after treating with GSE. Both of the increment in total bFGF and NO levels were correlated with the degree of growth inhibition. Changes involving cell shrinkage and detachment of cancer cells could readily be observed. Taken together, our results here suggest that growth inhibition induced by GSE in these solid tumour cell lines may involve both bFGF and NO regulations.

Gleditsia sinensis fruit extract is a potential chemotherapeutic agent in chronic and acute myelogenous leukemia

The anti-leukemia activity of the saponin rich Gleditsia sinensis Lam. fruit extract (GSE) was investigated on cancer cell lines and bone marrow cells obtained from consented patients with chronic myelogenous leukemia (CML) and acute myelogenous leukemia (AML) during presentation. The growth inhibitory activity of the extract was determined by [3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium] (MTS) assay. Colony formation assay was performed to investigate the regeneration potential. Cellular morphology change was studied. Apoptosis was demonstrated by DNA electrophoresis, reverse transcription polymerase chain reaction (RT-PCR) and flow cytometry. The mean concentration to inhibit the cell growth by 50% (MTS50) was 18+/-1.6 micro g/ml for K562 CML cell line and 12+/-1.3 micro g/ml for HL-60 acute promyelocytic leukemia cell line. Patient samples showed a mean MTS50 of 13-28 micro g/ml. Non-malignant hematological disorder bone marrow samples showed a mean MTS50 from 45 to 53 micro g/ml. Loss of regeneration property after treatment with GSE of these two cancer cell lines were confirmed by colony formation assay. GSE was able to induce cell shrinkage in K-562. DNA laddering was observed by incubating the leukemia cells with GSE. RT-PCR demonstrated that the pro-apoptic gene bax was induced while the anti-apoptic gene bcl-2 and cell cycle active gene PCNA were reduced. Flow cytometric analysis showed that the apoptotic effect of GSE on leukemia cell line was time- and dose-dependent. Thus GSE might be potentially used as a chemotherapeutic drug to treat patients with acute and chronic myelogenous leukemia.

Anti-angiogenic potential of Gleditsia sinensis fruit extract

Blood supply plays a crucial role in solid tumour development and leukaemogenesis. It has been suggested that blocking of angiogenesis could be possible in cancer therapy. We have demonstrated the antiproliferative activity of Gleditsia sinensis fruit extract (GSE) on various human solid tumour cancer cell lines as well as leukaemia cell lines and primary cultured leukaemia cells obtained from leukaemia patients. However, the antiangiogenic potential of GSE has not been demonstrated. Here we demonstrated that GSE could reduce vascular endothelial growth factor (VEGF) mRNA expression in dose- and time course-dependently in MDA-MB231 breast cancer and HepG2 hepatoblastoma cell lines as measured by reverse transcriptase polymerase chain reaction. Enzyme-linked immunosorbent assay further showed that GSE could reduce the VEGF secretion from various cancer cell lines including MDA-MB231, HepG2, HL-60 (acute promyelocytic leukaemia) and eleven primary cultured leukaemia cells obtained from acute myelogenous leukaemia patients. In vivo chick chorioallantoic membrane assay illustrated that GSE could reduce the angiogenic activity of basic fibroblast growth factor. Taken together, the information suggested that GSE could be potentially used as an angiogenic inhibitor in both solid tumour and leukaemia therapy.