Lupeol induces p53 and cyclin-B-mediated G2/M arrest and targets apoptosis through activation of caspase in mouse skin

Allyl isothiocyanate regulates oxidative stress, inflammation, cell proliferation, cell cycle arrest, apoptosis, angiogenesis, invasion and metastasis via interaction with multiple cell signaling pathways

Cancer growth is a molecular mechanism initiated by genetic and epigenetic modifications that are involved in cell proliferation, differentiation, apoptosis, and senescence pathways. Chemoprevention is an important strategy for cancer treatment that leads to blocking, reversing, or impeding the multistep process of tumorigenesis, including the blockage of its vital morphogenetic milestones viz. normal, preneoplasia, neoplasia, and metastasis. Naturally occurring phytochemicals are becoming ever more popular compared to synthetic drugs for many reasons, including safety, bioavailability, efficacy, and easy availability. Allyl isothiocyanate (AITC) is a natural compound present in all plants of the Cruciferae family, such as Brussels sprouts, cauliflower, mustard, cabbage, kale, horseradish, and wasabi. In vitro and in vivo studies carried out over the decades have revealed that AITC inhibits tumorigenesis without any toxicity and undesirable side effects. The bioavailability of AITC is exceedingly high, as it was reported that nearly 90% of orally administered AITC is absorbed. AITC exhibits multiple pharmacological properties among which its anticancer activity is the most significant for cancer treatment. Its anticancer activity is exerted via selective modulation of multiple cell signaling pathways related to oxidative stress, inflammation, cell proliferation, cell cycle arrest, apoptosis, angiogenesis, invasion, and metastasis. This review highlights the current knowledge on molecular targets that are involved in the anticancer effect of AITC associated with (i) inhibition of carcinogenic activation and induction of antioxidants, (ii) suppression of pro-inflammatory and cell proliferative signals, (iii) induction of cell cycle arrest and apoptosis, and (iv) inhibition of angiogenic and invasive signals related to metastasis.

Medicinal Plants Towards Modeling Skin Cancer

Skin cancer remains a major cause of mortality worldwide. It can be divided into melanoma and non-melanoma cancer, which comprise mainly squamous cell carcinoma and basal cell carcinoma. Although conventional therapies have ameliorated the management of skin cancer, the search for chemopreventive compounds is still the most effective and safer strategy to treat cancer. Nowadays, chemoprevention is recognized as a novel approach to prevent or inhibit carcinogenesis steps with the use of natural products. Crude extracts of plants and isolated phytocompounds are considered chemopreventive agents since they harbor anti-inflammatory, antioxidant and anti-oncogenic properties against many types of diseases and cancers. In this review, we will discuss the therapeutic effect and preventive potential of selected medicinal plants used as crude extracts or as phytocompounds against melanoma and non-melanoma cutaneous cancers.

Melatonin protects against apoptosis of megakaryocytic cells via its receptors and the AKT/mitochondrial/caspase pathway

Clinical studies have shown that melatonin lowers the frequency of thrombocytopenia in patients with cancer undergoing radiotherapy or chemotherapy. Here, we investigated the mechanisms by which melatonin promotes platelet formation and survival. Our results show that melatonin exerted protective effects on serum-free induced apoptosis of CHRF megakaryocytes (MKs). Melatonin promoted the formation of MK colony forming units (CFUs) in a dose-dependent manner. Using doxorubicin-treated CHRF cells, we found that melatonin rescued G2/M cell cycle arrest and cell apoptosis induced by doxorubicin. The expression of p-AKT was increased by melatonin treatment, an effect that was abolished by melatonin receptor blocker. In addition, we demonstrated that melatonin enhanced the recovery of platelets in an irradiated mouse model. Megakaryopoiesis was largely preserved in melatonin-treated mice. We obtained the same results in vivo from bone marrow histology and CFU-MK formation assays. Melatonin may exert these protective effects by directly stimulating megakaryopoiesis and inhibiting megakaryocyte apoptosis through activation of its receptors and AKT signaling.

Chemosensitization of Therapy Resistant Tumors: Targeting Multiple Cell Signaling Pathways by Lupeol, A Pentacyclic Triterpene

Background:

The resistance of cancer cells to different therapies is one of the major stumbling blocks for successful cancer treatment. Various natural and pharmaceuticals drugs are unable to control drug-resistance cancer cell's growth. Also, chemotherapy and radiotherapy have several side effects and cannot apply to the patient in excess. In this context, chemosensitization to the therapy-resistant cells by non-toxic phytochemicals could be an excellent alternative to combat therapy-resistant cancers.

Objective:

To review the currently available literature on chemosensitization of therapy resistance cancers by Lupeol for clinically approved drugs through targeting different cell signaling pathways.

Methods:

We reviewed relevant published articles in PubMed and other search engines from 1999 to 2019 to write this manuscript. The key words used for the search were “Lupeol and Cancer”, “Lupeol and Chemosensitization”, “Lupeol and Cell Signaling Pathways”, “Cancer Stem Cells and Lupeol” etc. The published results on the chemosensitization of Lupeol were compared and discussed.

Results:

Lupeol chemosensitizes drug-resistant cancer cells for clinically approved drugs. Lupeol alone or in combination with approved drugs inhibits inflammation in different cancer cells through modulation of expression of IL-6, TNF-α, and IFN-γ. Lupeol, through altering the expression levels of BCL-2, BAX, Survivin, FAS, Caspases, and PI3K-AKT-mTOR signaling pathway, significantly induce cell deaths among therapy-resistant cells. Lupeol also modulates the molecules involved in cell cycle regulation such as Cyclins, CDKs, P53, P21, and PCNA in different cancer types.

Conclusion:

Lupeol chemosensitizes the therapy-resistant cancer cells for the treatment of various clinically approved drugs via modulating different signaling pathways responsible for chemoresistance cancer. Thus, Lupeol might be used as an adjuvant molecule along with clinically approved drugs to reduce the toxicity and increase the effectiveness.

In silico evaluation of apoptogenic potential and toxicological profile of triterpenoids

AIM:

Caspases-3 and 8 are key mediators of intrinsic and extrinsic pathway of apoptosis, respectively. Triterpenoids of natural and synthetic origin reported as anticancer agents with apoptotic potential and hence may prove to be good candidates for in silico testing against caspases-3 and 8.

MATERIALS AND METHODS:

Various naturally-occurring and synthetic triterpenoids were subjected to activity prediction using PASS Online software, and among them, 67 compounds were selected for further processing. Protein structure of caspase-3 (3DEI) and caspase-8 (3KJQ) was obtained from the protein data bank and docked with selected triterpenoids using AutoDock Tools and AutoDock Vina. Toxicological profile was predicted based on clinical manifestations using PASS online software.

RESULTS:

The high docking score of -10.0, -9.9, -9.8, and -9.5 were shown by friedelin, tingenone, albiziasaponin A, and albiziasaponin C, respectively, for caspase-3, and -11.0, -9.6, -9.6, and -9.4 by β-boswellic acid, bryonolic acid, canophyllic acid, and CDDO, respectively, for caspase-8. Possible adverse events were predicted with varying degree of probability and major relevant effects were reported. Hydrostatic interactions along with formation of hydrogen bonds with specific amino acids in the binding pocket were identified with each triterpenoid.

CONCLUSION:

Lead molecules identified through this in silico study such as friedelin, tingenone, albiziasaponin, bryonolic acid, and canophyllic acid may be utilized for further in vitro/in vivo studies as apoptotic agents targeting caspases-3 and 8.

The anti-tumor activity of brown seaweed oligo-fucoidan via lncRNA expression modulation in HepG2 cells

Hepatocellular carcinoma (HCC) is the third most common cause of cancer-related death in Asia. HCC is less sensitive to chemotherapy and is known to express multidrug resistant genes to acquire resistance to chemotherapeutic agents, therefore the development of a potent HCC suppressor is essential in treating HCC. Our previous reports demonstrated that oligo-fucoidan from the brown seaweed Sargassum hemiphyllum elevates microRNA-29b to inhibit epithelial-mesenchymal transition in hepatoma cells. In this study, we aimed to examine in vitro effect of oligo-fucoidan in hepatocellular carcinoma through apoptosis and long noncoding RNA (lncRNA) pathway. Oligo-fucoidan was studied for its anti-hepatoma cells by MTT and DNA ladder analysis. And the mechanism was studied by flow cytometry, qPCR and western blot analysis. In this study, oligo-fucoidan induced sub-G1 phase cell cycle arrest and activation of caspases, indicating that the intrinsic and extrinsic apoptotic pathways were involved in the mechanism of oligo-fucoidan-induced cell death. Moreover, oligo-fucoidan significantly increased the expression of p53, p21, and p27, while cyclin-B1 and -D1 were decreased at the mRNA and protein levels. Finally, we showed that targeting apoptosis and cell cycle pathways could also contribute to the induction of the lncRNA-Saf and lncRNA-p21. Through human lncRNA profiler array analysis, the differential expression of lncRNAs in HCC cells following oligo-fucoidan exposure was further examined. These findings indicated that lncRNAs switched oligo-fucoidan-induced apoptosis, which might be potentially valuable in HCC adjuvant therapy.

Inhibitory Effect of Lupeol on MMPs Expression using Aged Fibroblast through Repeated UVA Irradiation

In this study, the aged dermal fibroblast model was constructed by repeated irradiation with UV light and the effect of lupeol, a triterpenoid, on anti-aging was confirmed. SA-β-galactosidase (SA-β-gal) stained aged cells increased by about 40% and expression of p-p53, p21, p16 and MMPs (MMP-1, -2, -3) increased in aged fibroblast. As an efficacy result, the treatment of lupeol on aged fibroblast induced by UVA repeated irradiation showed a dose-dependent reduction of SA-β-gal stained aged cells, the expression of p-p53, p21, p16 and inhibition of MMPs. Interestingly, lupeol increased dephosphorylation of p-ERK in repeated UV irradiated conditions. Additionally, lupeol compensated MMPs expression when p-ERK phosphorylation was inhibited by p-ERK inhibitor PD98059. Thus, these results showed that lupeol has a possible effect on MMPs expression using inhibition of the p-ERK pathway. Taken together, we confirmed that lupeol inhibits senescence through inhibiting MMP-1, -2, -3 as well as p-p53, p21 and p16 expression and SA-β-gal activity in repeated UVA-irradiated senescent FB models, therefore suggesting that lupeol may be useful as an anti-aging agent.

Targeted breast cancer therapy by harnessing the inherent blood group antigen immune system

Cancer gene therapy has attracted increasing attention for its advantages over conventional therapy in specific killing of tumor cells. Here, we attempt to prove a novel therapeutic approach that targets tumors by harnessing the blood antigen immune response system, which is inherently present in patients with breast cancers. Breast cancer MDA-MB-231 cells expressed blood group H antigen precursor. After ectopic expression of blood group A glycosyltransferase, we found that the H precursor was converted into the group A antigen, appearing on the surface of tumor cells. Incubation with group B plasma from breast cancer patients activated the antigen-antibody-complement cascade and triggered tumor cell killing. Interestingly, expression of blood A antigen also reduced tumorigenesis in breast cancer cells by inhibiting cell proliferation, migration, and tumor sphere formation. Cell cycle analysis revealed that cancer cells were paused at S phase due to the activation of cell cycle regulatory genes. Furthermore, pro-apoptotic genes were unregulated by the A antigen, including BAX, P21, and P53, while the anti-apoptotic BCL2 was down regulated. Importantly, we showed that extracellular HMGB1 and ATP, two critical components of the immunogenic cell death pathway, were significantly increased in the blood A antigen-expressing tumor cells. Collectively, these data suggest that blood antigen therapy induces specific cancer cell killing by activating the apoptosis and immunogenic cell death pathways. Further translational studies are thereby warranted to apply this approach in cancer immuno-gene therapy.

Effects of an irinotecan derivative, ZBH‑1208, on the immune system in a mouse model of brain tumor and its antitumor mechanism

The present study aimed to evaluate the inhibitory effects of an irinotecan derivative, ZBH‑1208, on brain tumors, and to explore the underlying molecular mechanisms. To determine the effects of ZBH‑1208, a brain tumor mouse model was established by transplanting B22 cells. Subsequently, the visceral indices of immune organs and white blood cell counts were determined, and the effects of ZBH‑1208 on the expression levels of cell cycle‑related proteins were assessed by western blotting. The tumor inhibition rates of 20 and 40 mg/kg ZBH‑1208 were 11.7 and 54.1%, respectively. Compared with the negative control group, ZBH‑1208 barely affected visceral indices or white blood cell count. Furthermore, the expression levels of p53, p21, cyclin‑dependent kinase 7 (CDK7), Wee1, phosphorylated (p)‑cell division cycle 2 (CDC2) (Tyr15), p‑CDC2 (Thr161) and cyclin B1 proteins were upregulated, whereas the expression levels of cyclin E were downregulated, and those of CDC2, CDK2 and CDC25C were barely altered. In conclusion, the present study demonstrated that ZBH‑1208 suppressed the growth of B22 mouse brain tumor xenografts, but did not affect their visceral indices or white blood cell counts. It was suggested that ZBH‑1208 exerted its effects by regulating the expression of p53, p21, Wee1, p‑CDC2 (Tyr15) and cyclin E proteins.

Regulation of cell signaling pathways by dietary agents for cancer prevention and treatment

Although it is widely accepted that better food habits do play important role in cancer prevention and treatment, how dietary agents mediate their effects remains poorly understood. More than thousand different polyphenols have been identified from dietary plants. In this review, we discuss the underlying mechanism by which dietary agents can modulate a variety of cell-signaling pathways linked to cancer, including transcription factors, nuclear factor κB (NF-κB), signal transducer and activator of transcription 3 (STAT3), activator protein-1 (AP-1), β-catenin/Wnt, peroxisome proliferator activator receptor- gamma (PPAR-γ), Sonic Hedgehog, and nuclear factor erythroid 2 (Nrf2); growth factors receptors (EGFR, VEGFR, IGF1-R); protein Kinases (Ras/Raf, mTOR, PI3K, Bcr-abl and AMPK); and pro-inflammatory mediators (TNF-α, interleukins, COX-2, 5-LOX). In addition, modulation of proteasome and epigenetic changes by the dietary agents also play a major role in their ability to control cancer. Both in vitro and animal based studies support the role of dietary agents in cancer. The efficacy of dietary agents by clinical trials has also been reported. Importantly, natural agents are already in clinical trials against different kinds of cancer. Overall both in vitro and in vivo studies performed with dietary agents strongly support their role in cancer prevention. Thus, the famous quote "Let food be thy medicine and medicine be thy food" made by Hippocrates 25 centuries ago still holds good.

Lupeol and Its Role in Chronic Diseases

Lupeol belongs to pentacyclic lupane-type triterpenes and exhibits in edible vegetables, fruits and many plants. Many researches indicated that lupeol possesses many beneficial pharmacological activities including antioxidant, anti-inflammatory, anti-hyperglycemic, anti-dyslipidemic and anti-mutagenic effects. From various disease-targeted animal models, these reports indicated that lupeol has anti-diabetic, anti-asthma, anti-arthritic, cardioprotective, hepatoprotective, nephroprotective, neuroprotective and anticancer efficiency under various routes of administration such as topical, oral, subcutaneous, intraperitoneal and intravenous. It is worth mentioning that clinical trials of lupeol were performed to treat canine oral malignant melanoma and human moderate skin acne in Japan and Korea. The detailed mechanism of anti-inflammatory, anti-diabetic, hepatoprotective and anticancer activities was further reviewed from published papers. These evidence indicate that lupeol is a multi-target agent to exert diverse pharmacological potency with many potential targeting proteins such as α-glucosidase, α-amylase, protein tyrosine phosphatase 1B (PTP 1B) and TCA cycle enzymes and targeting pathway such as IL-1 receptor-associated kinase-mediated toll-like receptor 4 (IRAK-TLR4), Bcl-2 family, nuclear factor kappa B (NF-kB), phosphatidylinositol-3-kinase (PI3-K)/Akt and Wnt/β-catenin signaling pathways. This review also provides suggestion that lupeol might be a valuable and potential lead compound to develop as anti-inflammatory, anti-diabetic, hepatoprotective and anticancer drugs.

Protective effects of lupeol against mancozeb-induced genotoxicity in cultured human lymphocytes

BACKGROUND

Lup-20(29)-en-3H-ol (Lupeol), a dietary pentacyclic triterpenoid has been shown to possess multiple medicinal activities including anti-inflammatory, anti-oxidant and anti-carcinogenic effects. Mancozeb is a widely used broad-spectrum fungicide with well-known carcinogenic hazards in rodents.

PURPOSE

The present study has been designed to investigate the protective effects of lupeol against mancozeb-induced genotoxicity and apoptosis in cultured human lymphocytes (CHLs).

METHODS

The genotoxic effect of mancozeb was evaluated by chromosomal aberration and micronucleus assays. The cell cycle kinetics and intracellular reactive oxygen species (ROS) generation was measured by flow cytometry. The levels of anti-oxidant enzymes and lipid peroxidation (LPO) were estimated by enzymatic assays. The localization of p65NF-κB was measured by immunocytochemical analysis. The differential expression of genes associated with genotoxicity was measured by qRT-PCR.

RESULTS

Mancozeb exposure (5µg/ml) for 24h caused significant induction of chromosomal aberrations (CAs) and micronuclei (MN) formation in CHLs. Pre-and post-treatment (25 and 50µg/ml) of lupeol for 24h significantly (p<0.05) reduced the frequency of CAs and MN induction, in a dose-dependent manner in mancozeb treated CHLs. Concomitantly, lupeol pre-treatment for 24h significantly increased the levels of anti-oxidant enzymes, superoxide dismutase (SOD) and catalase and decreased ROS generation and LPO. Additionally, lupeol pre-treatment significantly reduced mancozeb-induced apoptosis as shown by Sub-G1 peak analysis and annexin V-PI assay, in a dose dependent manner. Moreover, pre-treatment with lupeol attenuated mancozeb-induced NF-κB activation in CHLs. Furthermore, the results of qRT-PCR showed that lupeol pre-treatment significantly (p<0.05) decreased mancozeb-induced expression of DNA damage (p53, MDM2, COX-2, GADD45α and p21) and increased expression of DNA repair responsive genes (hOGG1 and XRCC1) in CHLs.

CONCLUSION

Taken together, our findings suggest that lupeol could attenuate mancozeb-induced oxidative stress, which in turn could inhibit NF-κB activation and thus provide protection against mancozeb-induced genotoxicity and apoptosis. So, lupeol could be used as a potent anti-oxidant regimen against pesticide induced genotoxicity in agricultural farm workers.

The chemokine receptor CXCR7 interacts with EGFR to promote breast cancer cell proliferation

Background

Recent advances have revealed a significant contribution of chemokines and their receptors in tumor growth, survival after chemotherapy, and organ-specific metastasis. The CXC chemokine receptor-7 (CXCR7) is the latest chemokine receptor implicated in cancer. Although over expressed in breast cancer cell lines and tumor tissues, its mechanism of action in breast cancer (BrCa) growth and metastasis is unclear. Studies in other cancers have implicated CXCR7 in cell proliferation, anti-apoptotic activity and cell-cell adhesion. The present study was initiated to examine the pattern of CXCR7 expression and its role in regulation of growth signaling in breast cancer.

Methods

The contribution of CXCR7 in BrCa cell proliferation was investigated in representative cell lines using real time quantitative PCR (q-PCR), proliferation assays, immunohistochemistry and immunoblotting. Phenotypic changes were examined after CXCR7 specific cDNA and siRNA transfection and expression levels were monitored by q-PCR. Further, the association of CXCR7 with epidermal growth factor receptor (EGFR) and modulation of its activity were investigated by western blotting, immunofluorescence, and in-situ proximity ligation assays in human BrCa cells and tissues.

Results

CXCR7 was expressed in both, estrogen receptor (ER) positive and negative BrCa cell lines. CXCR7 was also expressed unevenly in normal breast tissues and to a much higher extent in ER + cancer tissues. Depletion of CXCR7 in MCF7 BrCa cells by RNA interference decreased proliferation and caused cell cycle arrest. Further, proximity ligation assay (PLA) revealed colocalization of CXCR7 with EGFR in cancer tissues and cancer cell lines. CXCR7 depletion reduced levels of phospho-EGFR at Tyrosine1110 after EGF-stimulation and also reduced phosphorylation of ERK1/2, indicating a potentially direct impact on mitogenic signaling in MCF7 cells. Using siRNA to knockdown β-arrestin2 in cells with EGFR over expression we were able to nearly deplete the CXCR7-EGFR colocalization events, suggesting that β-arrestin2 acts as a scaffold to enhance CXCR7 dependent activation of EGFR after EGF stimulation.

Conclusions

These results demonstrate coupling of CXCR7 with EGFR to regulate proliferation of BrCa cells and suggest an important ligand-independent role of CXCR7 in BrCa growth. Thus, the CXCR7-EGFR axis is a promising target for breast cancer therapy.

Electronic supplementary material

The online version of this article (doi:10.1186/1476-4598-13-198) contains supplementary material, which is available to authorized users.

New Enlightenment of Skin Cancer Chemoprevention through Phytochemicals: In Vitro and In Vivo Studies and the Underlying Mechanisms

Skin cancer is still a major cause of morbidity and mortality worldwide. Skin overexposure to ultraviolet irradiations, chemicals, and several viruses has a capability to cause severe skin-related disorders including immunosuppression and skin cancer. These factors act in sequence at various steps of skin carcinogenesis via initiation, promotion, and/or progression. These days cancer chemoprevention is recognized as the most hopeful and novel approach to prevent, inhibit, or reverse the processes of carcinogenesis by intervention with natural products. Phytochemicals have antioxidant, antimutagenic, anticarcinogenic, and carcinogen detoxification capabilities thereby considered as efficient chemopreventive agents. Considerable efforts have been done to identify the phytochemicals which may possibly act on one or several molecular targets that modulate cellular processes such as inflammation, immunity, cell cycle progression, and apoptosis. Till date several phytochemicals in the light of chemoprevention have been studied by using suitable skin carcinogenic in vitro and in vivo models and proven as beneficial for prevention of skin cancer. This revision presents a comprehensive knowledge and the main molecular mechanisms of actions of various phytochemicals in the chemoprevention of skin cancer.

Multifunctional pentacyclic triterpenoids as adjuvants in cancer chemotherapy: a review

The protective adjuvants in chemotherapy.

Review of the phytochemical, pharmacological and toxicological properties of Alstonia Scholaris Linn. R. Br (Saptaparna)

The use of ethnornedical information has immensely contributed to health care, and scientific studies have shown that the evaluation of traditionally used medicines may provide leads towards effective drug discovery. Since antiquity, Alstonia scholaris connmonly known as devil's tree has been used for the treatment of many human ailments. Literature suggests that Alstonia scholaris is useful in treating malaria, abdominal disorders, dyspepsia, leprosy, skin diseases, tumors, chronic and foul ulcers, asthma, bronchitis, helminthiasis, agalactia, and debility. Preclinical studies have shown that it possesses anti-microbial, anti-diarrhoeal, anti-plasmodial, anti-oxidant, anti-inflammatory hepatoprotective, nootrophic, anti-stress, anti-fertility, immunomodulatory, analgesic, anti-ulcer, wound healing, anti-cancer, chemopreventive, radiation protection, radiation sensitization, and chemosensitization activities. The diverse pharmacological observations are supposed to be due to the presence of alkaloids, flavonoids and phenolic acids. The bark and leaf extract when administered orally did not induce lethality or adverse affects at the limit doses of 2 000 mg/kg body weight. However when administered intraperitoneally at high concentrations, the extract showed systemic and developmental toxicities. This review addresses the experimentally authenticated facts and also suggests the need for research on chemical and pharmacological properties of Alstonia scholaris.

Targeting inflammatory pathways by triterpenoids for prevention and treatment of cancer

Traditional medicine and diet has served mankind through the ages for prevention and treatment of most chronic diseases. Mounting evidence suggests that chronic inflammation mediates most chronic diseases, including cancer. More than other transcription factors, nuclear factor-kappaB (NF-κB) and STAT3 have emerged as major regulators of inflammation, cellular transformation, and tumor cell survival, proliferation, invasion, angiogenesis, and metastasis. Thus, agents that can inhibit NF-κB and STAT3 activation pathways have the potential to both prevent and treat cancer. In this review, we examine the potential of one group of compounds called triterpenes, derived from traditional medicine and diet for their ability to suppress inflammatory pathways linked to tumorigenesis. These triterpenes include avicins, betulinic acid, boswellic acid, celastrol, diosgenin, madecassic acid, maslinic acid, momordin, saikosaponins, platycodon, pristimerin, ursolic acid, and withanolide. This review thus supports the famous adage of Hippocrates, “Let food be thy medicine and medicine be thy food”.

Alstonia scholaris Linn R Br in the treatment and prevention of cancer: past, present, and future

Alstonia scholaris, commonly known as devil's tree, is an important medicinal plant in the various folk and traditional systems of medicine in Asia, Australia, and Africa. The decoction, mostly prepared from the bark, is used to treat a variety of diseases of which the most important is malaria. Furthermore, ethnomedicinal practices also suggest it to be of use in treating cancer, and preclinical studies performed with cultured neoplastic cells and tumor-bearing animals having validated these observations. Additionally, the phytochemicals like echitamine, alstonine, pleiocarpamine, O-methylmacralstonine, macralstonine, and lupeol are also reported to possess antineoplastic effects. In addition to the cytotoxic effects, A scholaris is also observed to possess radiomodulatory, chemomodulatory, and chemopreventive effects and free-radical scavenging, antioxidant, anti-inflammatory, antimutagenic, and immunomodulatory activities, all of which are properties efficacious in the treatment and prevention of cancer. The current review for the first time summarizes the results related to these properties. An attempt is also made to address the lacunae in these published studies and emphasize aspects that need further investigations for it to be of use in clinics in the future.

A selective eradication of human nonhereditary breast cancer cells by phenanthridine-derived polyADP-ribose polymerase inhibitors

Introduction

PARP-1 (polyADP-ribose polymerase-1) is known to be activated in response to DNA damage, and activated PARP-1 promotes DNA repair. However, a recently disclosed alternative mechanism of PARP-1 activation by phosphorylated externally regulated kinase (ERK) implicates PARP-1 in a vast number of signal-transduction networks in the cell. Here, PARP-1 activation was examined for its possible effects on cell proliferation in both normal and malignant cells.

Methods

In vitro (cell cultures) and in vivo (xenotransplants) experiments were performed.

Results

Phenanthridine-derived PARP inhibitors interfered with cell proliferation by causing G₂/M arrest in both normal (human epithelial cells MCF10A and mouse embryonic fibroblasts) and human breast cancer cells MCF-7 and MDA231. However, whereas the normal cells were only transiently arrested, G₂/M arrest in the malignant breast cancer cells was permanent and was accompanied by a massive cell death. In accordance, treatment with a phenanthridine-derived PARP inhibitor prevented the development of MCF-7 and MDA231 xenotransplants in female nude mice. Quiescent cells (neurons and cardiomyocytes) are not impaired by these PARP inhibitors.

Conclusions

These results outline a new therapeutic approach for a selective eradication of abundant nonhereditary human breast cancers.

Oridonin induces G2/M arrest and apoptosis via activating ERK-p53 apoptotic pathway and inhibiting PTK-Ras-Raf-JNK survival pathway in murine fibrosarcoma L929 cells

Oridonin was reported to induce L929 cell apoptosis via ROS-mediated mitochondrial and ERK pathways; however, the precise mechanisms by which oridonin induces cell death remain unclear. Herein, we found that oridonin treatment induced an increase in G(2)/M phase cell percentage. And, G(2)/M phase arrest was associated with down-regulation of cell cycle related cdc2, cdc25c and cyclinB levels, as well as up-regulation of p21 and p-cdc2 levels. In addition, we discovered that interruption of p53 activation decreased oridonin-induced apoptosis, and blocking ERK by specific inhibitors or siRNA suppressed oridonin-induced p53 activation. Moreover, inhibition of PTK, protein kinase C, Ras, Raf or JNK activation increased oridonin-induced apoptosis. Also, the level of Ras, Raf or JNK was down-regulated by oridonin, and the inhibition of PTK, Ras, Raf activation decreased p-JNK level. In conclusion, oridonin induces L929 cell G(2)/M arrest and apoptosis, which is regulated by promoting ERK-p53 apoptotic pathway and suppressing PTK-mediated survival pathway.