PBX3 is an important cofactor of HOXA9 in leukemogenesis

Although PBX proteins are known to increase DNA-binding/transcriptional activity of HOX proteins through their direct binding, the functional importance of their interaction in leukemogenesis is unclear.We recently reported that overexpression of a 4-homeobox-gene signature (ie, PBX3/HOXA7/HOXA9/HOXA11) is an independent predictor of poor survival in patients with cytogenetically abnormal acute myeloid leukemia (CA-AML). Here we show that it is PBX3, but not PBX1 or PBX2, that is consistently coexpressed with HOXA9 in various subtypes of CA-AML, particularly MLL-rearranged AML, and thus appears as a potential pathologic cofactor of HOXA9 in CA-AML. We then show that depletion of endogenous Pbx3 expression by shRNA significantly inhibits MLL-fusion-mediated cell transformation, and coexpressed PBX3 exhibits a significantly synergistic effect with HOXA9 in promoting cell transformation in vitro and leukemogenesis in vivo. Furthermore, as a proof of concept, we show that a small peptide, namely HXR9, which was developed to specifically disrupt the interactions between HOX and PBX proteins, can selectively kill leukemic cells with overexpression of HOXA/PBX3 genes. Collectively, our data suggest that PBX3 is a critical cofactor of HOXA9 in leukemogenesis, and targeting their interaction is a feasible strategy to treat presently therapy resistant CA-AML (eg, MLL-rearranged leukemia) in which HOXA/PBX3 genes are overexpressed.

Compound K, a Ginsenoside Metabolite, Inhibits Colon Cancer Growth via Multiple Pathways Including p53-p21 Interactions

Compound K (20-O-beta-D-glucopyranosyl-20(S)-protopanaxadiol, CK), an intestinal bacterial metabolite of ginseng protopanaxadiol saponins, has been shown to inhibit cell growth in a variety of cancers. However, the mechanisms are not completely understood, especially in colorectal cancer (CRC). A xenograft tumor model was used first to examine the anti-CRC effect of CK in vivo. Then, multiple in vitro assays were applied to investigate the anticancer effects of CK including antiproliferation, apoptosis and cell cycle distribution. In addition, a qPCR array and western blot analysis were executed to screen and validate the molecules and pathways involved. We observed that CK significantly inhibited the growth of HCT-116 tumors in an athymic nude mouse xenograft model. CK significantly inhibited the proliferation of human CRC cell lines HCT-116, SW-480, and HT-29 in a dose- and time-dependent manner. We also observed that CK induced cell apoptosis and arrested the cell cycle in the G1 phase in HCT-116 cells. The processes were related to the upregulation of p53/p21, FoxO3a-p27/p15 and Smad3, and downregulation of cdc25A, CDK4/6 and cyclin D1/3. The major regulated targets of CK were cyclin dependent inhibitors, including p21, p27, and p15. These results indicate that CK inhibits transcriptional activation of multiple tumor-promoting pathways in CRC, suggesting that CK could be an active compound in the prevention or treatment of CRC.

Hydrophobic flavonoids from Scutellaria baicalensis induce colorectal cancer cell apoptosis through a mitochondrial-mediated pathway

Scutellaria baicalensis extract (SbE) has been shown to exert chemopreventive effects on several types of cancer. Baicalin, a hydrophilic flavonoid found in SbE, may have opposing effects that decrease the antitumor potential of SbE against colorectal cancer. In this study, after removing baicalin, we prepared an aglycone-rich fraction (ARF) of SbE and evaluated its anti-proliferative activity and mechanisms of action. The flavonoids found in ARF, baicalin fraction (BF) and SbE were determined by high-performance liquid chromatography (HPLC). The effects of ARF, BF, SbE and representative flavonoids on the proliferation of HCT-116 and HT-29 human colorectal cancer cells were determined by an MTS assay. The cell cycle, the expression of cyclins A and B1 and cell apoptosis were assayed using flow cytometry. Apoptosis-related gene expression was visualized by quantitative real-time polymerase chain reaction (PCR), and mitochondrial membrane potential was estimated following staining with JC-1. HPLC analysis showed that ARF contained two hydrophobic flavonoids, baicalein and wogonin, and that BF contained only baicalin. SbE had little anti-proliferative effect on the colorectal cancer cells; cancer cell growth was even observed at certain concentrations. ARF exerted potent anti-proliferative effects on the cancer cells. By contrast, BF increased cancer cell growth. ARF arrested cells in the S and G2/M phases, increased the expression of cyclins A and B1, and significantly induced cell apoptosis. Multiple genes in the mitochondrial pathway are involved in ARF-induced apoptosis, and subsequent cellular functional analysis validated the involvement of this pathway. These results suggest that removing baicalin from SbE produces an ARF that significantly inhibits the growth of colorectal cancer cells, and that the mitochondrial apoptotic pathway plays a role in hydrophobic flavonoid-induced apoptosis.

Paraptosis and NF-κB activation are associated with protopanaxadiol-induced cancer chemoprevention

Background

Protopanaxadiol (PPD) is a triterpenoid that can be prepared from steamed ginseng. PPD possesses anticancer potential via caspase-dependent apoptosis. Whether paraptosis, a type of the caspase-independent cell death, is also induced by PPD has not been evaluated.

Methods

Cell death, the cell cycle and intracellular reactive oxygen species (ROS) were analyzed by flow cytometry after staining with annexin V/PI, PI/RNase or H2DCFDA. We observed morphological changes by crystal violet staining assay. Mitochondrial swelling was measured by ultraviolet–visible spectrophotometry. The activation of NF-κB was measured by luciferase reporter assay.

Results

At comparable concentrations of 5-fluorouracil, PPD induced more cell death in human colorectal cancer cell lines HCT-116 and SW-480. We demonstrated that PPD induced paraptosis in these cancer cells. PPD treatment significantly increased the percentage of cancer cells with cytoplasmic vacuoles. After the cells were treated with PPD and cycloheximides, cytoplasmic vacuole generation was inhibited. The paraptotic induction effect of PPD was also supported by the results of the mitochondrial swelling assay. PPD induced ROS production in cancer cells, which activated the NF-κB pathway. Blockage of ROS by NAC or PS-1145 inhibited the activation of NF-κB signaling.

Conclusions

PPD induces colorectal cancer cell death in part by induction of paraptosis. The anticancer activity of PPD may be enhanced by antioxidants such as green tea, which also inhibit the activation of NF-κB signaling.

Trends in Scientific Publications of Chinese Medicine

Traditional Chinese medicine (TCM) is an important component of complementary and alternative medicine (CAM). The fast economic growth of mainland China in the past two decades has promoted the use of TCM beyond Chinese-speaking countries. Chinese researchers have published more TCM research studies in CAM-related professional journals, including the American Journal of Chinese Medicine (AJCM), the highest impact journal in Chinese medicine. The consistent increase of the impact factor of the AJCM suggests a growth in TCM popularity. This study analyzed articles published in the AJCM between 2004 and 2011. Our data show that while enthusiasm towards cardiovascular, nervous system and inflammation related research remained high, more herbal investigations and cancer studies were published. Furthermore, a reduction in TCM formulation studies was replaced by increasing botanical single constituent research. Examples of frequently cited studies, including those before 2004, are presented. These data are not only important to the scientific community for recognition of trends in TCM research, but also for providing information to TCM researchers who are targeting potentially highly cited studies.

Epigallocatechin Gallate (EGCG) is the most effective cancer chemopreventive polyphenol in green tea

Green tea is a popular drink consumed daily by millions of people around the world. Previous studies have shown that some polyphenol compounds from green tea possess anticancer activities. However, systemic evaluation was limited. In this study, we determined the cancer chemopreventive potentials of 10 representative polyphenols (caffeic acid, CA; gallic acid, GA; catechin, C; epicatechin, EC; gallocatechin, GC; catechin gallate, CG; gallocatechin gallate, GCG; epicatechin gallate, ECG; epigallocatechin, EGC; and epigallocatechin gallate, EGCG), and explored their structure-activity relationship. The effect of the 10 polyphenol compounds on the proliferation of HCT-116 and SW-480 human colorectal cancer cells was evaluated using an MTS assay. Cell cycle distribution and apoptotic effects were analyzed by flow cytometry after staining with propidium iodide (PI)/RNase or annexin V/PI. Among the 10 polyphenols, EGCG showed the most potent antiproliferative effects, and significantly induced cell cycle arrest in the G1 phase and cell apoptosis. When the relationship between chemical structure and anticancer activity was examined, C and EC did not show antiproliferative effects, and GA showed some antiproliferative effects. When C and EC esterified with GA to produce CG and ECG, the antiproliferative effects were increased significantly. A similar relationship was found between EGC and EGCG. The gallic acid group significantly enhanced catechin’s anticancer potential. This property could be utilized in future semi-synthesis of flavonoid derivatives to develop novel anticancer agents.

Herbal medicines as adjuvants for cancer therapeutics

In the United States, many patients, including cancer patients, concurrently take prescription drugs and herbal supplements. Co-administration of prescription medicines and herbal supplements may have negative outcomes via pharmacodynamic and pharmacokinetic herb-drug interactions. However, multiple constituents in botanicals may also yield beneficial pharmacological activities. Botanicals could possess effective anticancer compounds that may be used as adjuvants to existing chemotherapy to improve efficacy and/or reduce drug-induced toxicity. Herbal medicines, such as ginseng, potentiated the effects of chemotherapeutic agents via synergistic activities, supported by cell cycle evaluations, apoptotic observations, and computer-based docking analysis. Since botanicals are nearly always administrated orally, the role of intestinal microbiota in metabolizing ginseng constituents is presented. Controlled clinical studies are warranted to verify the clinical utility of the botanicals in cancer chemoprevention.

Metabolism of ginseng and its interactions with drugs

Ginseng is an herbal medicine used worldwide. It is reported to have a wide range of pharmacological activities because of a diversified group of steroidal saponins called ginsenosides. Compared to extensive pharmacological studies of ginseng, the pharmacokinetics, especially the metabolism of this herb, has received less attention. In this article we review the known pharmacokinetic data on ginseng. Understanding ginseng's pharmacokinetics may reduce the potential for interactions in patients who use both ginseng and prescription medications. In addition, bioavailability after taking ginseng orally is low, and the metabolites of ginsenosides produced by gut microbiota may be biologically active. One ginseng metabolite, Compound K, and its potential for cancer chemoprevention is also discussed. An active ginseng metabolite may differ in distribution and clearance from its parent compound, and the parent compound and its metabolite may be bioactive by similar or different mechanisms. Thus, further investigation of ginseng metabolites is needed for predicting the therapeutic outcome with ginseng.

The synergistic apoptotic interaction of panaxadiol and epigallocatechin gallate in human colorectal cancer cells

Panaxadiol (PD) is a purified sapogenin of ginseng saponins, which exhibits anticancer activity. Epigallocatechin gallate (EGCG), a major catechin in green tea, is a strong botanical antioxidant. In this study, we investigated the possible synergistic anticancer effects of PD and EGCG on human colorectal cancer cells and explored the potential role of apoptosis in the synergistic activities. Effects of selected compounds on HCT-116 and SW-480 human colorectal cancer cells were evaluated by a modified trichrome stain cell proliferation analysis. Cell cycle distribution and apoptotic effects were analyzed by flow cytometry after staining with PI/RNase or annexin V/PI. Cell growth was suppressed after treatment with PD (10 and 20 µm) for 48 h. When PD (10 and 20 µm) was combined with EGCG (10, 20, and 30 µm), significantly enhanced antiproliferative effects were observed in both cell lines. Combining 20 µm of PD with 20 and 30 µm of EGCG significantly decreased S-phase fractions of cells. In the apoptotic assay, the combination of PD and EGCG significantly increased the percentage of apoptotic cells compared with PD alone (p < 0.01). The synergistic apoptotic effects were also supported by docking analysis, which demonstrated that PD and EGCG bound in two different sites of the annexin V protein. Data from this study suggested that apoptosis might play an important role in the EGCG-enhanced antiproliferative effects of PD on human colorectal cancer cells.

Analysis of Panax notoginseng metabolites in rat bile by liquid chromatography-quadrupole time-of-flight mass spectrometry with microdialysis sampling

A dynamic microdialysis sampling method with liquid chromatography-quadrupole time-of-flight mass spectrometry (Q-TOF-MS) was developed for rapid and sensitive analysis of the metabolite profile of Panax notoginseng extract (PNE) in rat bile. In vivo studies in male Sprague-Dawley rats were performed with microdialysis probes implanted into the bile duct before bile samples were collected from 0 to 12h. Metabolites of PNE were identified using dynamic adjustment of the fragmentor voltage to produce structure-relevant fragment ions. The mass accuracy of precursor and fragment ions was typically within 5 ppm of the theoretical values. We identified 7 compounds: 4 parent compounds (notoginsenoside R1, ginsenosides Rg1, Rb1, and Rd) and 3 metabolites (ginsenosides Rg2, Rh2, and compound K). Data from this study suggest that this microdialysis technique could be used in notoginseng saponin metabolic animal studies.

Identification of metabolites of Buyang Huanwu decoction in rat urine using liquid chromatography-quadrupole time-of-flight mass spectrometry

In the present study, rapid resolution liquid chromatography was coupled with quadrupole time-of-flight tandem mass spectrometry (RRLC-Q-TOF-MS) to identify the absorbed components and metabolites in rat urine after oral administration of Buyang Huanwu decoction (BYHWD). After oral administration of BYHWD, urine samples were collected and pretreated by solid phase extraction. The mass measurements were accurate within 5 ppm of error for all the protonated molecules, and subsequent fragment ions offered higher quality structural information for interpretation of the fragmentation pathways of various compounds. A total of 50 compounds were detected in rat urine samples within 20 min, including 12 parent compounds and 38 metabolites. Except for three prototype components (Hydroxysafflor yellow A, Paeoniflorin, and Amygdalin), the metabolites identified mainly came from Radix Astragali, Radix Angelicae Sinensis, and Rhizoma Chuanxiong. The results indicated that glucuronidation and sulfation were the major metabolic pathways of isoflavonoids, while glutathione conjugation, glucuronidation and sulfation were the main metabolic pathways of phthalides. No saponin-related metabolites were detected. The present study provided important structural information on the metabolism of BYHWD. Furthermore, the results of this work have demonstrated the feasibility of the RRLC/ESI-Q-TOF-MS approach for rapid and reliable characterization of metabolites from herbal medicines.

Abstract 1975: The mitochondrial pathway in baicalein and wogonin-induced apoptosis in human colorectal cancer cells

Treating colorectal cancer patients commonly involves several conventional modalities, including surgery, radiation, and chemotherapy. The complexity of colorectal cancer, however, requires additional alternatives to improve the therapeutic efficacy of conventional treatment and the quality of life of cancer patients. Medicinal botanicals have recently gained attention as additions to colorectal cancer management. Numerous effective anticancer drugs have been developed from botanicals, and identifying new herbal sources for ideal chemoprevention remains essential to advance the treatment of colorectal cancer. Scutellaria baicalensis extract (SbE) has chemopreventive effects on several cancers. Baicalin, a major constituent of SbE, also may have the negative effect of decreasing the anti-tumor potential of SbE. In this study, we prepared a baicalin knockout fraction (BKF) of SbE and evaluated its antiproliferative activity and mechanism of action. The constituents of BKF, baicalin fraction (BF), and SbE were quantified by HPLC. We then used an MTS assay to determine the effects of BKF, BF, SbE, and the representative flavonoids on the proliferation of human colorectal cancer cells (HCT-116 and HT-29). Cell cycle, cyclin A expression and cell apoptosis were assayed by flow cytometry. Apoptosis-related gene expression was visualized by quantitative real-time polymerase chain reaction (PCR), and mitochondrial membrane potential was estimated after staining with JC-1. HPLC analysis showed that BKF contained baicalein and wogonin; BF contained only baicalin. SbE had little antiproliferative effect on cancer cells, even increasing cancer cell growth at certain concentrations. BF increased cancer cell growth. BKF showed potent antiproliferative effects on cancer cells. BKF arrested cells in the S and G2/M phases, increased expression of cyclin A, and significantly induced cell apoptosis. Multiple genes in the mitochondrial pathway were involved in BKF-induced apoptosis, and subsequent cellular functional analysis validated the pathway. These results suggest that knocking out baicalin from SbE produces a BKF that significantly inhibits the growth of colorectal cancer cells. The active anticancer compounds in SbE are flavonoid aglycons, baicalein and wogonin, and the mitochondrial apoptotic pathway is part of baicalein and wogonin-induced apoptosis. (This work was supported in part by the NIH/NCCAM grants AT004418 and AT005362).

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 1975. doi:1538-7445.AM2012-1975

Baicalein protects against doxorubicin-induced cardiotoxicity by attenuation of mitochondrial oxidant injury and JNK activation

The cardiotoxicity of doxorubicin limits its clinical use in the treatment of a variety of malignancies. Previous studies suggest that doxorubicin-associated cardiotoxicity is mediated by reactive oxygen species (ROS)-induced apoptosis. We therefore investigated if baicalein, a natural antioxidant component of Scutellaria baicalensis, could attenuate ROS generation and cell death induced by doxorubicin. Using an established chick cardiomyocyte model, doxorubicin (10 µM) increased cell death in a concentration- and time-dependent manner. ROS generation was increased in a dose-response fashion and associated with loss of mitochondrial membrane potential. Doxorubicin also augmented DNA fragmentation and increased the phosphorylation of ROS-sensitive pro-apoptotic kinase c-Jun N-terminal kinase (JNK). Adjunct treatment of baicalein (25 µM) and doxorubicin for 24 h significantly reduced both ROS generation (587 ± 89 a.u. vs. 932 a.u. ± 121 a.u., P < 0.01) and cell death (30.6 ± 5.1% vs. 46.8 ± 8.3%, P < 0.01). The dissipated mitochondrial potential and increased DNA fragmentation were also ameliorated. Along with the reduction of ROS and apoptosis, baicalein attenuated phosphorylation of JNK induced by doxorubicin (1.7 ± 0.3 vs. 3.0 ± 0.4-fold, P < 0.05). Co-treatment of cardiomyocytes with doxorubicin and JNK inhibitor SP600125 (10 µM; 24 h) reduced JNK phosphorylation and enhanced cell survival, suggesting that the baicalein protection against doxorubicin cardiotoxicity was mediated by JNK activation. Importantly, concurrent baicalein treatment did not interfere with the anti-proliferative effects of doxorubicin in human breast cancer MCF-7 cells. In conclusion, baicalein adjunct treatment confers anti-apoptotic protection against doxorubicin-induced cardiotoxicity without compromising its anti-cancer efficacy.

Safety and Tolerability of Ganoderma lucidum in Healthy Subjects: A Double-Blind Randomized Placebo-Controlled Trial

Ganoderma lucidum is a herbal medicine commonly used in oriental countries as a remedy for treating various medical conditions. In this controlled study, we evaluated the safety and tolerance of oral administration of Ganoderma lucidum in 16 human volunteers who received 2 grams of the extract or placebo twice daily for 10 consecutive days. During the study, information from subjective questionnaires were obtained, electrocardiograms, complete blood counts, blood chemistry analysis and urinalysis were performed. In addition, blood tests reflecting immunity were done. Our data showed that compared to placebo group, no adverse effects were observed after the extract intake. Although there were no obvious changes in CD4, CD8, and CD19 levels after the extract, CD56 cell count increased during the study and returned to baseline 10 days after the herbal intake. However, due to relatively high variability and small sample size, this CD56 increase did not achieve statistical significance, and remains to be re-evaluated in the future. It appears that an additional long-term safety and tolerance trial with herbal dose-escalating design is warranted.

Potential Anti-Cancer Activities of Furanodiene, A Sesquiterpene from Curcuma wenyujin

Furanodiene is a sesquiterpene extracted from the essential oil of the rhizome of Curcuma wenyujin Y.H. Chen et C. Ling (Wen Ezhu). Furanodiene is the primary component in Wen Ezhu's essential oil, accounting for more than 20% by weight. In vitro, MTT assay was used to compare the inhibitory effects of furanodiene and Wen Ezhu's essential oil on 11 human cancer cell lines. Compared to the essential oil, furanodiene showed stronger growth inhibitions on Hela, Hep-2, HL-60, PC3, SGC-7901 and HT-1080 cells with IC50 between 0.6–4.8 μg/ml. In vivo, furanodiene was also found to exhibit inhibitory effects on the growth of uterine cervical (U14) and sarcoma 180 (Sl80) tumors in mice. Our data suggests that furanodiene, an active component from the essential oil of Wen Ezhu, possesses efficacy against uterine cervical cancer.

Effects of Antioxidant Herbs on Chemotherapy-Induced Nausea and Vomiting in a Rat-Pica Model

Nausea and vomiting are significant adverse effects of chemotherapeutic agents like cisplatin, and cause significant patient morbidity. Cisplatin treatment results in oxidant gut injury, which is postulated to be the primary cause of nausea and vomiting. We evaluated the effects of two antioxidant herbs, Scutellaria baicalensis and American ginseng berry, on cisplatin-induced nausea and vomiting using a rat model. Rats react to emetic or nausea-producing stimuli, such as cisplatin, with altered feeding habits, manifested by increased kaolin consumption (pica). We measured pica in rats to quantify cisplatin-induced nausea. We observed that pretreatment of rats with S. baicalensis or ginseng berry extracts resulted in a significant reduction in cisplatin-induced pica. The in vitro free radical scavenging ability of the herbal extract observed in the study, further confirmed the antioxidant action of the herb. We conclude that herbal antioxidants may have a role in attenuating cisplatin-induced nausea and vomiting.

Synergistic Effect of Scutellaria baicalensis and Grape Seed Proanthocyanidins on Scavenging Reactive Oxygen Species in Vitro

Scutellaria baicalensis (SbE) is a commonly used Chinese herb medicine and grape seed proanthocyanidins is a popular herbal supplement in the United States. Both herbs have been shown to possess potent antioxidant effects. Using an in vitro model to produce the reactive oxygen species (ROS) generation ( H 2 O 2/ FeSO 4 for hydroxyl radicals, xanthine/xanthine oxidase for suproxide), we observed that Scutellaria baicalensis and grape seed proanthocyanidins acted synergistically to scavenge ROS. Our data suggest that a combination of these two herbs can potentially enhance their antioxidant efficacy, allowing lower dosages of each drug to be used. This has the advantage of avoiding possible side effects that may arise when higher doses of a single herb are used in an attempt to achieve a maximum degree of antioxidant activity.

Naphthoquinone components from Alkanna tinctoria (L.) Tausch show significant antiproliferative effects on human colorectal cancer cells

Our research to seek active compounds against human colorectal cancer from the root of Alkanna tinctoria (L.) Tausch led to the isolation of two naphthoquinones, alkannin (1) and angelylalkannin (2). The antiproliferative effects of the two compounds on human colon cancer cells HCT-116 and SW-480 were determined by the 3,4-(5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium salt (MTS) method. Cell cycle profile and cell apoptosis were determined using flow cytometry. Both of the two compounds showed significant inhibitory effects on the cancer cells. For alkannin (1) and angelylalkannin (2), the median inhibitory concentration (IC₅₀) values were 2.38 and 4.76 µM for HCT-116 cells, while for SW-480 cells they were 4.53 and 7.03 µM, respectively. The potential antiproliferative mechanisms were also explored. At concentrations between 1-10 µM, both compounds arrested the cell cycle at the G1 phase and induced cell apoptosis.

Chemical and pharmacological studies of Oplopanax horridus, a North American botanical

Oplopanax horridus (OH), or Devil's club, is an ethnobotanical used by the indigenous people native to the Pacific Northwest of North America. There are three species in the genus Oplopanax, and OH is the only species that is distributed in North America. Compared with the extensive research on OH's "cousin," American ginseng, there is comparatively little reported about the chemical makeup and pharmacological effects of OH. Nevertheless, there has been some research over the past few years that shows promise for the future usage perspectives of OH. To date, 17 compounds were isolated and elucidated, including polyynes, glycosides, lignans, and polyenes, with most of the attention being paid to the polyynes. Gas chromatography (GC) and high-performance liquid chromatography (HPLC) were used to determine the contents of volatile compounds and polyynes in the essential oil and extracts of OH. For the pharmacological studies, antibacterial and antidiabetes effects of polyynes were reported. Our recent study has focused more on the anticancer effects of OH and the involved mechanisms of action. In this review, we will summarize the research status in the botany, phytochemistry, and pharmacology of OH.

Ginsenoside compound K, not Rb1, possesses potential chemopreventive activities in human colorectal cancer

Ginsenoside compound K (C-K) is an intestinal microbiota metabolite of ginsenoside Rb1, a major constituent in American ginseng. However, previous ginseng anti-cancer observations were largely focused on ginseng parent compounds but not metabolites, and anti-colorectal cancer studies on C-K were limited. This study investigated the anti-proliferative effects of C-K when compared to those of Rb1, and the related mechanisms of action, in HCT-116 and SW-480 colorectal cancer cells. The effects of Rb1 and C-K on the proliferation of HCT-116 and SW-480 human colorectal cancer cells were compared using an MTS assay. Cell cycle and cell apoptosis were assayed using flow cytometry. Enzymatic activities of caspases were determined by colorimetric assay, and interactions of C-K and caspases were explored by docking analysis. C-K showed significant anti-proliferative effects in HCT-116 and SW-480 cells at concentrations of 30-50 µM. At the same concentrations, Rb1 did not show any effects, while C-K arrested the cells in the G1 phase, and significantly induced cell apoptosis. Compared to HCT-116 (p53 wild-type), the p53 mutant cell line SW-480 was more sensitive to C-K as assessed by cell cycle regulation and apoptosis induction. C-K activated expression of caspases 8 and 9, consistent with docking analysis. The docking data suggested that C-K forms hydrogen bonds with Lys253, Thr904 and Gly362 in caspase 8, and with Thr62, Ser63 and Arg207 in caspase 9. C-K, but not its parent ginsenoside Rb1, showed significant anti-proliferative and pro-apoptotic effects in human colorectal cancer cells. These results suggest that C-K could be a potentially effective anti-colorectal cancer agent.

Ultra-performance liquid chromatography and time-of-flight mass spectrometry analysis of ginsenoside metabolites in human plasma

American ginseng is a commonly used herbal medicine in the United States. When ginseng is taken orally, its active components, ginsenosides, are reportedly biotransformed by intestinal microbiota. Previous pharmacokinetic evaluations of ginseng in humans have focused on its parent constituents. However, the metabolites, especially those transformed by intestinal microbiota, have not been carefully studied. We used an ultra-performance liquid chromatography/time-of-flight mass spectrometry (UPLC/TOF-MS) method to determine 15 ginsenosides and/or metabolites and their bioavailability in humans. Six healthy human subjects received a single oral dose of 10 g of American ginseng root powder, after which samples of their blood were collected at 0, 2, 4, 7, 9 and 12 h for measurement of ginsenoside/metabolite levels in plasma. Ginsenosides Rb1, Rd, Rg2 and compound K (C-K) were detected in human plasma samples at different time points. The Rb1 concentration peak was 19.90 ± 5.43 ng/ml at 4 h. C-K was detected from 7 h to 12 h with 7.32 ± 1.35 ng/ml at 12 h. Since the last time point was at 12 h, C-K peak level was not observed. The areas under the concentration curves (AUC) from 0 to 12 h were 155.0 ± 19.5 ng⋅h/ml for Rb1 and 26.4 ± 6.4 ng⋅h/ml for C-K, respectively. The gradual decrease of Rb1 levels and the delayed increase in levels of C-K observed in human subjects supported previous reports that enteric microbiota played a key role in transforming Rb1 to C-K.

Caspase-mediated pro-apoptotic interaction of panaxadiol and irinotecan in human colorectal cancer cells

OBJECTIVES

Panaxadiol is a purified sapogenin of ginseng saponins that exhibits anticancer activity. Irinotecan is a second-line anticancer drug, but clinical treatment with irinotecan is limited due to its side effects. In this study, we have investigated the possible synergistic anticancer effects of panaxadiol and irinotecan on human colorectal cancer cells and explored the potential role of apoptosis in their synergistic activity.

KEY FINDINGS

The combination of panaxadiol and irinotecan significantly enhanced antiproliferative effects in HCT-116 cells (P< 0.05). Cell cycle analysis demonstrated that combining irinotecan treatment with panaxadiol significantly increased the G1-phase fractions of cells, compared with irinotecan treatment alone. In apoptotic assays, the combination of panaxadiol and irinotecan significantly increased the percentage of apoptotic cells compared with irinotecan alone (P<0.01). Increased activity of caspase-3 and caspase-9 was observed after treating with panaxadiol and irinotecan. The synergistic apoptotic effects were supported by docking analysis, which demonstrated that panaxadiol and irinotecan bound two different chains of the caspase-3 protein.

CONCLUSIONS

Data from this study suggested that caspase-3- and caspase-9-mediated apoptosis may play an important role in the panaxadiol enhanced antiproliferative effects of irinotecan on human colorectal cancer cells.