Triterpenes augment the inhibitory effects of anticancer drugs on growth of human esophageal carcinoma cells in vitro and suppress experimental metastasis in vivo

NF-kappa B modulation is involved in celastrol induced human multiple myeloma cell apoptosis

Celastrol is an active compound extracted from the root bark of the traditional Chinese medicine Tripterygium wilfordii Hook F. To investigate the effect of celastrol on human multiple myeloma cell cycle arrest and apoptosis and explore its molecular mechanism of action. The activity of celastrol on LP-1 cell proliferation was detected by WST-8 assay. The celastrol-induced cell cycle arrest was analyzed by flow cytometry after propidium iodide staining. Nuclear translocation of the nuclear factor kappa B (NF-κB) was observed by fluorescence microscope. Celastrol inhibited cell proliferation of LP-1 myeloma cell in a dose-dependent manner with IC50 values of 0.8817 µM, which was mediated through G1 cell cycle arrest and p27 induction. Celastrol induced apoptosis in LP-1 and RPMI 8226 myeloma cells in a time and dose dependent manner, and it involved Caspase-3 activation and NF-κB pathway. Celastrol down-modulated antiapoptotic proteins including Bcl-2 and survivin expression. The expression of NF-κB and IKKa were decreased after celastrol treatment. Celastrol effectively blocked the nuclear translocation of the p65 subunit and induced human multiple myeloma cell cycle arrest and apoptosis by p27 upregulation and NF-kB modulation. It has been demonstrated that the effect of celastrol on NF-kB was HO-1-independent by using zinc protoporphyrin-9 (ZnPPIX), a selective heme oxygenase inhibitor. From the results, it could be inferred that celastrol may be used as a NF-kB inhibitor to inhibit myeloma cell proliferation.

Advanced hepatocellular carcinoma responds to MK615, a compound extract from the Japanese apricot "Prunus mume"

MK615, a compound extracted from the Japanese apricot "Prunus mume" has been reported to have in vitro anti-tumor activities against several cancer cell lines, including hepatocellular carcinoma (HCC). However, the clinical effects and feasibility of administering MK615 for patients with HCC were unknown. We experienced a case with advanced HCC for which MK615 was effective against both lymph node and pulmonary metastases. A 60-year-old female underwent surgical resection of a 9 cm HCC in the right lobe. The pathological diagnosis was moderately differentiated HCC with vascular invasion. The HCC recurred in the liver 8 mo after the surgery. Radiofrequency ablation and transarterial infusion chemotherapy were performed, but the recurrence was not controlled. One year after the intrahepatic recurrence, pulmonary and lymph metastasis appeared. Sorafenib was administered, but was not effective. Then, MK615 was administered as a final alternative therapy after informed consent was obtained from the patient. Three months later, her alpha-fetoprotein level decrease and both the lymph node and pulmonary metastases decreased in size. The patient has survived for more than 17 mo after the MK615 administration, and was in good condition. Although further investigations are necessary to clarify its safety and efficacy in humans, MK615 may be useful for the treatment of HCC, without serious adverse effects.

Radiosensitizing effect of oleanolic acid on tumor cells through the inhibition of GSH synthesis in vitro

Oleanolic acid (OA) is a natural pentacyclic triterpenoid that has been used in traditional medicine as an anticancer and anti-inflammatory agent. The aim of our study was to investigate whether or not OA increases the radiosensivity of tumor cells, and the relative mechanism was also investigated. Clonogenic assay was used to observe the radiosensitivity of C6 and A549 cells following different treatments. The alteration of intracellular DNA damage was determined using a micronucleus (MN) assay. In order to identify the mechanism of OA-mediated radiosensitization of tumor cells, the levels of glutathione (GSH) in irradiated cells following various pretreatments were determined using glutathione reductase/5,5'-dithiobis-(2-nitrobenzoic acid) (DTNB) recycling assay. Under the same condition, the activities of γ-glutamylcysteine synthetase (γ-GCS) and GSH synthase (GSS), both key enzymes for GSH synthesis, were detected using appropriate methods. In order to confirm the radiosensitizing effect of OA on cancer cells by attenuating GSH, N-acetylcysteine (NAC) was added to cells in culture for 12 h before irradiation. The results showed that the combined treatment of radiation with OA significantly decreased the clonogenic growth of tumor cells and enhanced the numbers of intracellular MN compared to irradiation alone. Furthermore, it was found that the synthesis of cellular GSH was inhibited concomitantly with the downregulation of γ-GCS activity. Therefore, the utilization of OA as a radiosensitizing agent for irradiation-inducing cell death offers a potential therapeutic approach to treat cancer.

Ezrin dephosphorylation/downregulation contributes to ursolic acid-mediated cell death in human leukemia cells

Ezrin links the actin filaments with the cell membrane and has a functional role in the apoptotic process. It appears clear that ezrin is directly associated with Fas, leading to activation of caspase cascade and cell death. However, the exact role of ezrin in ursolic acid (UA)-induced apoptosis remains unclear. In this study, we show for the first time that UA induces apoptosis in both transformed and primary leukemia cells through dephosphorylation/downregulation of ezrin, association and polarized colocalization of Fas and ezrin, as well as formation of death-inducing signaling complex. These events are dependent on Rho-ROCK1 signaling pathway. Knockdown of ezrin enhanced cell death mediated by UA, whereas overexpression of ezrin attenuated UA-induced apoptosis. Our in vivo study also showed that UA-mediated inhibition of tumor growth of mouse leukemia xenograft model is in association with the dephosphorylation/downregulation of ezrin. Such findings suggest that the cytoskeletal protein ezrin may represent an attractive target for UA-mediated lethality in human leukemia cells.

Ursolic acid induces ER stress response to activate ASK1-JNK signaling and induce apoptosis in human bladder cancer T24 cells

Here we studied the cellular mechanisms of ursolic acid's anti-bladder cancer ability by focusing on endoplasmic reticulum stress (ER stress) signaling. We show that ursolic acid induces a significant ER stress response in cultured human bladder cancer T24 cells. ER stress inhibitor salubrinal, or PERK silencing, diminishes ursolic acid-induced anti-T24 cell effects. Salubrinal inhibits ursolic acid-induced CHOP expression, Bim ER accumulation and caspase-3 activation in T24 cells. Ursolic acid induces IRE1-TRAF2-ASK1 signaling complex formation to activate pro-apoptotic ASK1-JNK signaling. We suggest that ER stress contributes to ursolic acid's effects against bladder cancer cells.

Hypouricemic effect of the methanol extract from Prunus mume fruit in mice

CONTEXT

The fruit of the Prunus mume Sieb. et Zucc (Rosaceae) is used as a health food or medicinal material in traditional herb medicine for a long time in Eastern Asian countries.

OBJECTIVE

Our present study investigated the hypouricemic effect of the methanol extract from P. mume fruit (MPMF) in mice with potassium oxonate-induced hyperuremia.

MATERIALS AND METHODS

Effect of MPMF (35, 70 and 140 mg/kg, p.o.) administrated for 7 days on the serum, liver, urinary uric acid levels and liver xanthine oxidase (XO) activity were assessed in mice.

RESULTS

Hyperuricemic mice induced by potassium oxonate demonstrated an elevation in serum and liver uric acid levels (11.0 mg/dL and 0.52 mg/g tissue) and a reduction in urinary uric acid levels (49.9 mg/dL). Oral administration of 140 mg/kg MPMF for 7 days reversed the abnormalities in serum, liver and urinary uric acid levels (7.1 mg/dL, 0.37 mg/g tissue and 69.7 mg/dL, respectively). In addition, 70 and 140 mg/kg MPMF (3.1 and 2.9 nmol/min per mg protein) inhibited liver XO activity compared with hyperuricemic mice (3.9 nmol/min per mg protein).

DISCUSSION AND CONCLUSION

The results indicated that the beneficial hypouricaemic effect of MPMF may be mediated, at least in part, by inhibiting XO activity in the liver. Our study suggests that P. mume and its extracts may have a considerable potential for development as an anti-gout agent for clinical application.

Ursolic acid inhibits growth and metastasis of human colorectal cancer in an orthotopic nude mouse model by targeting multiple cell signaling pathways: chemosensitization with capecitabine

PURPOSE

Development of chemoresistance, poor prognosis, and metastasis often renders the current treatments for colorectal cancer (CRC) ineffective. Whether ursolic acid, a component of numerous medicinal plants, either alone or in combination with capecitabine, can inhibit the growth and metastasis of human CRC was investigated.

EXPERIMENTAL DESIGN

The effect of ursolic acid on proliferation of CRC cell lines was examined by mitochondrial dye uptake assay, apoptosis by esterase staining, NF-κB activation by DNA-binding assay, and protein expression by Western blot. The effect of ursolic acid on the growth and chemosensitization was also examined in orthotopically implanted CRC in nude mice.

RESULTS

We found that ursolic acid inhibited the proliferation of different colon cancer cell lines. This is correlated with inhibition of constitutive NF-κB activation and downregulation of cell survival (Bcl-xL, Bcl-2, cFLIP, and survivin), proliferative (cyclin D1), and metastatic (MMP-9, VEGF, and ICAM-1) proteins. When examined in an orthotopic nude mouse model, ursolic acid significantly inhibited tumor volume, ascites formation, and distant organ metastasis, and this effect was enhanced with capecitabine. Immunohistochemistry of tumor tissue indicated that ursolic acid downregulated biomarkers of proliferation (Ki-67) and microvessel density (CD31). This effect was accompanied by suppression of NF-κB, STAT3, and β-catenin. In addition, ursolic acid suppressed EGF receptor (EGFR) and induced p53 and p21 expression. We also observed bioavailability of ursolic acid in the serum and tissue of animals.

CONCLUSION

Overall, our results show that ursolic acid can inhibit the growth and metastasis of CRC and further enhance the therapeutic effects of capecitabine through the suppression of multiple biomarkers linked to inflammation, proliferation, invasion, angiogenesis, and metastasis.

Efficacy of MK615 for the treatment of patients with liver disorders

AIM: To investigate the hepatoprotective effect of MK615, a Japanese apricot extract, in an animal model, and its clinical therapeutic effect.

METHODS: Wistar rats were administered physiological saline (4 mL/kg) or MK615 solution (4 mL/kg) for 7 d. On the sixth d, acute hepatic injury was induced by administering a single intraperitoneal injection (ip) of D-galactosamine hydrochloride (D-GalN) (600 mg/kg). Plasma levels of alanine aminotransferase (ALT) and aspartate aminotransferase (AST) were determined, and liver tissues were used for histopathological analysis. Fifty-eight patients with liver disorders [hepatitis C (n = 40), non-alcoholic fatty liver disease (n = 15), and autoimmune liver disease (n = 3)] were orally administered commercially available Misatol ME-containing MK615 (13 g/d) daily for 12 wk. Blood and urine were sampled immediately before and 6 wk, 12 wk, and 16 wk after the start of intake to measure various biochemical parameters. The percentage change in ALT and AST levels after 12 wk from the pre-intake baseline served as a primary endpoint.

RESULTS: D-GalN effectively induced acute hepatic injury in the rats. At 48 h after the ip injection of D-GalN, the plasma levels of ALT (475.6 ± 191.5 IU/L vs 225.3 ± 194.2 IU/L, P < 0.05) and AST (1253.9 ± 223.4 IU/L vs 621.9 ± 478.2 IU/L, P < 0.05) in the MK615 group were significantly lower than the control group. Scattered single cell necrosis, loss of hepatocytes, and extensive inflammatory cell infiltration were observed in hepatic tissue samples collected from the control group. However, these findings were less pronounced in the group receiving MK615. At the end of the clinical study, serum ALT and AST levels were significantly decreased compared with pre-intake baseline levels from 103.5 ± 58.8 IU/L to 71.8 ± 39.3 IU/L (P < 0.05) and from 93.5 ± 55.6 IU/L to 65.5 ± 34.8 IU/L (P < 0.05), respectively. A reduction of ≥ 30% from the pre-study baseline ALT level was observed in 26 (45%) of the 58 patients, while 25 (43%) patients exhibited similar AST level reductions. The chronic hepatitis C group exhibited significant ALT and AST level reductions from 93.4 ± 51.1 IU/L to 64.6 ± 35.1 IU/L (P < 0.05) and from 94.2 ± 55.5 IU/L to 67.2 ± 35.6 IU/L (P < 0.05), respectively. A reduction of ≥ 30% from the pre-study baseline ALT level was observed in 20 (50%) of the 40 patients. ALT levels in both the combined ursodeoxycholic acid (UDCA) treatment and the UDCA uncombined groups were significantly lower after Misatol ME administration. MK615 protected hepatocytes from D-GalN-induced cytotoxicity in rats. Misatol ME decreased elevated ALT and AST levels in patients with liver disorders.

CONCLUSION: These results suggest that MK615 and Misatol ME are promising hepatoprotective agents for patients with liver disorders.

Bioavailability, distribution, and antioxidative effects of selected triterpenes in mice

This study analyzed the content of eight triterpenes (oleanolic acid, ursolic acid, arjunolic acid, asiatic acid, boswellic acid, corosolic acid, madecassic acid, and maslinic acid) in ten vegetables and eight fruits. These compounds at 0.5% were supplied to mice for 4 or 8 weeks. The bioavailability, tissue distribution, and antioxidative protection of these triterpenes were examined. Results showed that triterpenes were detected in eight vegetables and six fruits. Basil and brown mustard contained seven test triterpenes, in the range of 14-102 mg/100 g dry weight. The level of each triterpene in plasma, brain, heart, liver, kidney, colon, and bladder increased as the feeding period was increased from 4 weeks to 8 weeks (P < 0.05). Renal homogenates from mice with triterpene intake had greater antioxidative effects against glucose-induced glutathione loss and malondialdehyde and oxidized glutathione production when compared with those from control groups (P < 0.05). These data support that these triterpenes were absorbed and deposited in their intact forms, which in turn exerted in vivo antioxidative protection.

Ursolic acid inhibits cigarette smoke extract-induced human bronchial epithelial cell injury and prevents development of lung cancer

Cigarette smoking is the main cause of chronic obstructive pulmonary disease and lung cancer. The present study was aimed to explore the chemopreventive effect of ursolic acid (UA) on these diseases. In the CSE treated normal human bronchial epithelial cell model, UA alleviated cytotoxicity caused by CSE, recovered the intracellular redox balance, and relieved the stimulation of external deleterious factors as well. UA mitigated CSE-induced DNA damage through the Nrf2 (nuclear factor erythroid 2-related factor 2) pathway. Moreover, UA inhibited lung cancer development in the model established by A549 cells in nude mice in vivo. For the first time, our results indicate that UA could be developed as a potential lung cancer chemopreventive agent.

DIOL triterpenes block profibrotic effects of angiotensin II and protect from cardiac hypertrophy

Background

The natural triterpenes, erythrodiol and uvaol, exert anti-inflammatory, vasorelaxing and anti-proliferative effects. Angiotensin II is a well-known profibrotic and proliferative agent that participates in the cardiac remodeling associated with different pathological situations through the stimulation and proliferation of cardiac fibroblasts. Therefore, the aim of the study was to investigate the preventive effects of the natural triterpenes erythrodiol and uvaol on the proliferation and collagen production induced by angiotensin II in cardiac myofibroblasts. Their actions on cardiac hypertrophy triggered by angiotensin II were also studied.

Methodology/Principal Findings

The effect of erythrodiol and uvaol on angiotensin II-induced proliferation was evaluated in cardiac myofibroblasts from adult rats in the presence or the absence of the inhibitors of PPAR-γ, GW9662 or JNK, SP600125. The effect on collagen levels induced by angiotensin II was evaluated in cardiac myofibroblasts and mouse heart. The presence of low doses of both triterpenes reduced the proliferation of cardiac myofibroblasts induced by angiotensin II. Pretreatment with GW9662 reversed the effect elicited by both triterpenes while SP600125 did not modify it. Both triterpenes at high doses produced an increase in annexing-V binding in the presence or absence of angiotensin II, which was reduced by either SP600125 or GW9662. Erythrodiol and uvaol decreased collagen I and galectin 3 levels induced by angiotensin II in cardiac myofribroblasts. Finally, cardiac hypertrophy, ventricular remodeling, fibrosis, and increases in myocyte area and brain natriuretic peptide levels observed in angiotensin II-infused mice were reduced in triterpene-treated animals.

Conclusions/Significance

Erythrodiol and uvaol reduce cardiac hypertrophy and left ventricle remodeling induced by angiotensin II in mice by diminishing fibrosis and myocyte area. They also modulate growth and survival of cardiac myofibroblasts. They inhibit the angiotensin II-induced proliferation in a PPAR-γ-dependent manner, while at high doses they activate pathways of programmed cell death that are dependent on JNK and PPAR-γ.

Ursolic acid-induced AMP-activated protein kinase (AMPK) activation contributes to growth inhibition and apoptosis in human bladder cancer T24 cells

Ursolic acid (UA) has shown the anti-tumor properties against a number of human cancers both in vivo and in vitro, however, its effect in bladder cancer and the corresponding mechanisms of action remain largely unknown. Here we found that UA dose-dependently induced growth inhibition and apoptosis in human bladder cancer T24 cells, and activation of AMP-activated protein kinase (AMPK) may contribute to the process. Our Western-blot results demonstrated a significant AMPK activation after UA treatment in T24 cells. Notably, knockdown of AMPKα by the targeted shRNA largely inhibited UA-induced T24 cell growth inhibition and apoptosis, while an AMPK activator 5-aminoimidazole-4-carboxamide-1-β-D-ribofuranoside (AICAR) or a constitutively active form of AMPK mimic UA's effect. We found the ceramide level was increased after UA treatment in T24 cells, and UA-induced AMPK activation and T24 cell apoptosis were inhibited by ceramide synthase inhibitor fumonisin B1, and was enhanced by exogenously adding cell permeable short-chain ceramide (C6), suggesting that ceramide might serve as an upstream signal for AMPK activation. Further, activation of AMPK by UA promoted c-Jun N-terminal kinase (JNK) activation, but inhibited mTOR complex 1 (mTORC1) signaling to cause survivin down-regulation. Our study suggests that activation of AMPK by UA contributes to growth inhibition and apoptosis in human bladder cancer cells.

Autophagy inhibition enhances ursolic acid-induced apoptosis in PC3 cells

The phosphoinositol 3-kinase/Akt pathway plays a critical role in oncogenesis and the dysregulation of this pathway through loss of PTEN is a particularly common phenomenon in aggressive prostate cancers. Several recent studies have indicated that ursolic acid (UA), a pentacyclic triterpenoid, and its derivatives inhibit the growth of cancer cells by cell cycle arrest and the stimulation of apoptosis. In the present study, we report a novel autophagic response of UA in PTEN-deficient PC3 prostate cancer cells. As one of the major types of programmed cell death, autophagy has been observed in response to several anticancer drugs and demonstrated to be responsible for cell death. UA-induced autophagy in PC3 cells is associated with the reduced cell viability and the enhanced expression of LC3-II, an autophagosome marker in mammals, and monodansylcadaverine incorporation into autolysosomes. Furthermore, we found that UA exhibited anti-proliferative effects characterized by G1 phase arrest and autophagy at an early stage that precedes apoptosis. We also show that UA-induced autophagy in PC3 cells are mediated through the Beclin-1 and Akt/mTOR pathways. Inhibition of autophagy by either 3-methyladenine or Beclin-1/Atg5 small interfering RNA enhanced UA-induced apoptosis. Taken together, our data suggest that autophagy functions as a survival mechanism in PC3 cells against UA-induced apoptosis and a rational for the use of autophagy inhibitors in combination with UA as a novel modality of cancer therapy.

A new development of triterpene acid-containing extracts from Viscum album L. displays synergistic induction of apoptosis in acute lymphoblastic leukaemia

OBJECTIVES

Aqueous Viscum album L. extracts are widely used for anti-cancer therapies. Due to their low solubility, triterpenes (which are known to act on cancers), do not occur in aqueous extracts in significant amounts. Using cyclodextrins, we have found it possible to solubilize mistletoe triterpene acids and to determine their effects on acute lymphoblastic leukaemia (ALL) in vitro and in vivo.

MATERIALS AND METHODS

A C.B-17/SCID model of pre-B ALL (NALM-6) was used to test efficacy and mechanisms of treatment with lectin- and triterpene acid containing preparations in vivo. Cytotoxicity of increasing concentrations of V. album L. preparations was assessed in vitro. Apoptosis was determined using mitochondrial membrane potential measurements, annexin V/PI, western blot analyses and caspase inhibitor assays.

RESULTS

Solubilized triterpene acid- or lectin-containing V. album L. extracts inhibited cell proliferation and demonstrated cytotoxic properties in vitro. Annexin V/PI and mitochondrial membrane potential assays indicated that dose-dependent induction of apoptosis was the main mechanism. Combination (viscumTT) of lectin- (viscum) and triterpene-containing (TT) extracts resulted in greatest induction of apoptosis. Furthermore, caspase activity demonstrated that these extracts were able to induce apoptosis through both caspase-8 and -9 dependent pathways. In vivo experimentation showed that treatment of mice with viscumTT combination prolonged mean survival to 50.5 days compared to 39.3 days in the phosphate-buffered saline group.

CONCLUSION

Here for the first time, we have demonstrated that either solubilized triterpene acids or lectins and combinations thereof, induce dose-dependent apoptosis in the ALL cell line NALM-6 via caspase-8 and -9 dependent pathways.

Inhibition of tumor progression by naturally occurring terpenoids

CONTEXT

Cancer is a major public health problem in India and many other parts of the world. Its two main characteristics are uncontrolled cell growth and metastasis. Natural products represent a rich source of compounds that have found many applications in various fields of medicines and therapy including cancer therapy. Effective ingredients in several plant-derived medicinal extracts are terpenoid compounds and many terpenes have biological activities and are used for the treatment of human diseases.

OBJECTIVES

This review attempted to collect all available published scientific literature of eight naturally occurring terpenoids and their effect on inhibition of tumor progression.

METHODS

The present review is about eight potent naturally occurring terpenoids that have been studied for their pharmacological properties in our lab and this review includes 130 references compiled from all major databases.

RESULTS

Literature survey revealed that triterpenoids, such as glycyrrhizic acid, ursolic acid, oleanolic acid, and nomilin, the diterpene andrographolide, and the monoterpenoids like limonene and perillic acid had shown immunomodulatory and antitumor activities. All of them could induce apoptosis in various cancer cells by activating various proapoptotic signaling cascades. Many of these terpenoids found to inhibit metastatic progression and tumor-induced angiogenesis. The molecular mechanisms that involved in these activities include inhibition of various oncogenic and anti-apoptotic signaling pathways and suppression or nuclear translocation of various transcription factors including nuclear factor kappa B (NF-κB).

CONCLUSION

The chemopreventive and chemoprotective effects of these compounds point toward their possible role in modern anticancer therapies.

Combining betulinic acid and mithramycin a effectively suppresses pancreatic cancer by inhibiting proliferation, invasion, and angiogenesis

Both betulinic acid (BA) and mithramycin A (MIT) exhibit potent antitumor activity through distinct mechanisms of Sp1 inhibition. However, it is unknown whether a combination of these two compounds results in a synergistic inhibitory effect on pancreatic cancer growth and/or has a therapeutic advantage over gemcitabine. In xenograft mouse models of human pancreatic cancer, treatment with either BA or MIT alone showed dose-dependent antitumor activity but led to systemic side effects as measured by overall weight loss. Treatment with a nontoxic dose of either compound alone had only marginal antitumor effects. Importantly, combination treatment with nontoxic doses of BA and MIT produced synergistic antitumor activity, including inhibitory effects on cell proliferation, invasion, and angiogenesis. The treatment combination also produced less discernible side effects than therapeutic doses of gemcitabine. Moreover, combined treatment of BA and MIT resulted in drastic inhibition of Sp1 recruitment onto Sp1 and VEGF promoters, leading to transcriptional inhibition of both Sp1 and VEGF and downregulation of Sp1 and VEGF protein expression. Ectopic overexpression of Sp1 rendered tumor cells resistant to BA, MIT, and the combination of the two. Overall, our findings argue that Sp1 is an important target of BA and MIT and that their combination can produce an enhanced therapeutic response in human pancreatic cancer.

Determination of triterpenic acids in human serum by high-performance liquid chromatography: triterpenoid interaction with serum protein

Terpenic acids are under development as therapeutic agents in numerous treatments. In support of pharmacokinetic and toxicological evaluations, a robust assay based on high-performance liquid chromatography (HPLC) was developed for the analysis of the terpenoids in human serum. For a clear understanding of the differences in biological activity of these compounds, the interactions between oleanolic or betulinic acids and human serum protein have been studied by ultraviolet-visible (UV-vis) absorption under physiological conditions. A combination of liquid/liquid extraction, centrifugation, and consecutive HPLC resulted in simultaneous separation, identification, and quantification of the oleanolic, betulinic, and ursolic acids. The validity of the developed method was established by determining linearity, recovery, precision, accuracy, limit of detection, and quantification. Detection limits were in the range of 3.3-4.3 ng/mL, and linearity values ranged up to 1 μg/mL. The repeatability of the method was good. All compounds can be well-distinguished by order of elution during liquid chromatography. The pentacyclic triterpenoids have been identified by retention time comparison to pure standards and quantified by an internal standard. The results by UV-vis absorption spectra experiments (240-340 nm) indicate that protein structures have been perturbed in the presence of oleanolic and betulinic acids.

Ursolic acid, a pentacyclin triterpene, potentiates TRAIL-induced apoptosis through p53-independent up-regulation of death receptors: evidence for the role of reactive oxygen species and JNK

Discovery of the molecular targets of traditional medicine and its chemical footprints can validate the use of such medicine. In the present report, we investigated the effect of ursolic acid (UA), a pentacyclic triterpenoid found in rosemary and holy basil, on apoptosis induced by TRAIL. We found that UA potentiated TRAIL-induced apoptosis in cancer cells. In addition, UA also sensitized TRAIL-resistant cancer cells to the cytokine. When we investigated the mechanism, we found that UA down-regulated cell survival proteins and induced the cell surface expression of both TRAIL receptors, death receptors 4 and 5 (DR4 and -5). Induction of receptors by UA occurred independently of cell type. Gene silencing of either receptor by small interfering RNA reduced the apoptosis induced by UA and the effect of TRAIL. In addition, UA also decreased the expression of decoy receptor 2 (DcR2) but not DcR1. Induction of DRs was independent of p53 because UA induced DR4 and DR5 in HCT116 p53(-/-) cells. Induction of DRs, however, was dependent on JNK because UA induced JNK, and its pharmacologic inhibition abolished the induction of the receptors. The down-regulation of survival proteins and up-regulation of the DRs required reactive oxygen species (ROS) because UA induced ROS, and its quenching abolished the effect of the terpene. Also, potentiation of TRAIL-induced apoptosis by UA was significantly reduced by both ROS quenchers and JNK inhibitor. In addition, UA was also found to induce the expression of DRs, down-regulate cell survival proteins, and activate JNK in orthotopically implanted human colorectal cancer in a nude mouse model. Overall, our results showed that UA potentiates TRAIL-induced apoptosis through activation of ROS and JNK-mediated up-regulation of DRs and down-regulation of DcR2 and cell survival proteins.

MK615, a prospective anti-proliferative agent, enhances CD4/CD8 ratio after exposure to irradiation

PURPOSE

Recently, it was found that MK615 possessed an anti-proliferative ability on treated cancer cells as a consequence of triterpenoid compounds. It is well known that radiation affects cellular-mediated immunity in cancer patients who are treated with radiotherapy. Similarly, the ability of triterpenoid compounds to enhance the cellular-mediated immunity has been observed. Therefore, in the present study, we attempted to investigate the effect of MK615 on both cancer cells and cellular-mediated immunity after irradiation.

MATERIALS AND METHODS

After mice were inoculated with mouse mammary carcinoma (FM3A) cells, they were categorised as follows: Non-treated, irradiated with 5 Gy, treated with 660 μg/day MK615 (MK615, an extract from the Japanese apricot) and lastly exposed to both irradiation and MK615. Afterward, mice were sacrificed and spleens were utilised to measure the cluster of differentiation 4 and 8 (CD4 and CD8) using flowcytometry. Simultaneously, in vitro study, human alveolar basal epithelial carcinomic (A549), mouse lymphoma (EL4) and FM3A cell lines were examined. Growth inhibition was assessed via colony, cell viability and apoptotic assays.

RESULTS

The median survival was in favour of the MK615-treated group (26.1 ± 1.9 days) compared with non-treated group (22.3 ± 2.3 days) (p < 0.05). Approximately 50% reduction of the CD4/CD8 ratio was observed following the exposure to irradiation alone. However, this ratio was comparable between the non-treated and both MK615-treated groups. Additionally, only the dual treatment was associated with tumour volume reduction. In contrast, in vitro study showed that MK615 had no significant (p ≥ 0.1) effect on the selected cell lines with or without irradiation.

CONCLUSION

MK615 has a potential to reduce tumour volume and may normalise cellular-mediated immunity level following the exposure to irradiation.

Pentacyclic triterpenoids from olive fruit and leaf

This work establishes a new procedure for the extraction and analysis of pentacyclic triterpenes, with which fruits and leaves from three Spanish olive cultivars ("Picual", "Hojiblanca", and "Arbequina") has been studied. The leaf contains important amounts of oleanolic acid (3.0-3.5% DW), followed by significant concentrations of maslinic acid and minor levels of ursolic acid, erythrodiol, and uvaol. The abundance and profile of triterpenoids change during the leaf ontogeny. In the fruit, triterpenes are exclusively located in the epicarp at concentrations 30-fold lower than that in the leaf. Maslinic acid is the main triterpenoid, only accompanied of oleanolic acid. Along the ripening the levels of these triterpenes decreased. All the analyzed leaves and fruits come from the same agricultural estate, with identical climate and culturing conditions. For this reason, the found differences could majorly be attributable to the genetic factors of the olive cultivars.

Aqueous extracts of Fructus Ligustri Lucidi enhance the sensitivity of human colorectal carcinoma DLD-1 cells to doxorubicin-induced apoptosis via Tbx3 suppression

Chemoresistance has imposed a great challenge for cancer therapy. Fructus Ligustri Lucidi (FLL) is one of the commonest Chinese herbs that has been used for thousand years. This study shows that the aqueous extract of FLL (AFLL) enhanced the sensitivity of DLD-1 colon cancer cells to doxorubicin-induced apoptosis. Furthermore, Tbx3 expression was found to be suppressed by AFLL when the expression of tumor suppressor genes p14 and p53 were activated. Therefore, reduction of Tbx3 rescued the dysregulated P14(ARF)-P53 signaling, which in turn contributed to the sensitivity of DLD-1 cells to doxorubicin-induced apoptosis. As a conclusion, the findings suggest that FLL has a potential of being an appealing agent for auxiliary chemotherapy in treatment of human colorectal carcinoma.

Betulinic acid, a natural compound with potent anticancer effects

New therapies using novel mechanisms to induce tumor cell death are needed with plants playing a crucial role as a source for potential anticancer compounds. One highly promising class of natural compounds are the triterpenoids with betulinic acid (BetA) as the most prominent representative. In-vitro studies have identified this agent as potently effective against a wide variety of cancer cells, also those derived from therapy-resistant and refractory tumors, whereas it has been found to be relatively nontoxic for healthy cells. In-vivo preclinically applied BetA showed some remarkable anticancer effects and a complete absence of systemic toxicity in rodents. BetA also cooperated with other therapies to induce tumor cell death and several potent derivatives have been discovered. Its antitumor activity has been related to its direct effects on mitochondria where it induces Bax/Bak-independent cytochrome-c release.

The establishment of a new mouse model with orthotopic esophageal cancer showing the esophageal stricture

We established a promising new experimental animal model with an orthotopic xenograft of esophageal cancer that successfully represents poor oral intake, a major clinical feature of esophageal cancer. The advantage of this model is that no surgical technique is required, only the injection of a cell suspension by a needle and syringe via the esophageal lumen from the mouth, which provides a high reproducibility of tumor implantation and a rapid progress of outcome. We propose that this model is useful to study cancer-related outcomes and for developing new therapies for esophageal cancer, and we expect it to make a contribution to clinical practice.