Antitumor Effect of Periplocin in TRAIL-Resistant Human Hepatocellular Carcinoma Cells through Downregulation of IAPs

Periplocin inhibits hepatocellular carcinoma progression and reduces the recruitment of MDSCs through AKT/NF-κB pathway

AIMS

We aimed to evaluate the effect of periplocin on inhibiting hepatocellular carcinoma (HCC) and further determine its mechanisms.

MAIN METHODS

Cytotoxic activity of periplocin against HCC cells was tested by CCK-8 and colony formation assays. The antitumor effects of periplocin were evaluated in human HCC SK-HEP-1 xenograft and murine HCC Hepa 1-6 allograft mouse models. Flow cytometry was used to measure cell cycle distribution, apopotosis, and the number of myeloid-derived suppressor cells (MDSCs). Hoechst 33258 dye was applied to observe the nuclear morphology. Network pharmacology was performed to predict possible signaling pathways. Drug affinity responsive target stability assay (DARTS) was used to evaluate AKT binding of periplocin. Western blotting, immunohistochemistry, and immunofluorescence were used to examine the protein expression levels.

KEY FINDING

Periplocin inhibited cell viability with IC₅₀ values from 50 nM to 300 nM in human HCC cells. Periplocin disrupted cell cycle distribution and promoted cell apoptosis. Moreover, AKT was predicted as the target of periplocin by network pharmacology, which was confirmed by that AKT/NF-κB signaling was inhibited in periplocin-treated HCC cells. Periplocin also inhibited the expression of CXCL1 and CXCL3, leading to decreased accumulation of MDSCs in HCC tumors.

SIGNIFICANCE

These findings reveal the function of periplocin in inhibiting HCC progression by G₂/M arrest, apoptosis and suppression of MDSCs accumulation through blockade of the AKT/NF-κB pathway. Our study further suggests that periplocin has the potential to be developed as an effective therapeutic agent for HCC.

Dual targets of lethal apoptosis and protective autophagy in liver cancer with periplocymarin elicit a limited therapeutic effect

Cardiac glycosides (CGs) are candidate anticancer agents that function by increasing [Ca²⁺]i to induce apoptotic cell death in several types of cancer cells. However, new findings have shown that the anti‑cancer effects of CGs involve complex cell‑signal transduction mechanisms. Hence, exploring the potential mechanisms of action of CGs may provide insight into their anti‑cancer effects and thus aid in the selection of the appropriate CG. Periplocymarin (PPM), which is a cardiac glycoside, is an active ingredient extracted from Cortex periplocae. The role of PPM was evaluated in HepG2 cells and xenografted nude mice. Cell proliferation, real‑time ATP rate assays, western blotting, cell apoptosis assays, short interfering RNA transfection, the patch clamp technique, electron microscopy, JC‑1 staining, immunofluorescence staining and autophagic flux assays were performed to evaluate the function and regulatory mechanisms of PPM in vitro. The in vivo activity of the PPM was assessed using a mouse xenograft model. The present study demonstrated that PPM synchronously activated lethal apoptosis and protective autophagy in liver cancer, and the initiation of autophagy counteracted the inherent pro‑apoptotic capacity and impaired the anti‑cancer effects. Specifically, PPM exerted a pro‑-apoptotic effect in HepG2 cells and activated macroautophagy by initiation of the AMPK/ULK1 and mTOR signaling pathways. Activation of macroautophagy counteracted the pro‑apoptotic effects of PPM, but when it was combined with an autophagy inhibitor, the anti‑cancer effects of PPM in mice bearing HepG2 xenografts were observed. Collectively, these results indicated that a self‑limiting effect impaired the pro‑apoptotic effects of PPM in liver cancer, but when combined with an autophagy inhibitor, it may serve as a novel therapeutic option for the management of liver cancer.

Proscillaridin A Sensitizes Human Colon Cancer Cells to TRAIL-Induced Cell Death

Tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) is a cytotoxic cytokine that induces cancer cell death by binding to TRAIL receptors. Because of its selective cytotoxicity toward cancer cells, TRAIL therapeutics, such as recombinant TRAIL and agonistic antibodies targeting TRAIL receptors, have garnered attention as promising cancer treatment agents. However, many cancer cells acquire resistance to TRAIL-induced cell death. To overcome this issue, we searched for agents to sensitize cancer cells to TRAIL-induced cell death by screening a small-molecule chemical library consisting of diverse compounds. We identified a cardiac glycoside, proscillaridin A, as the most effective TRAIL sensitizer in colon cancer cells. Proscillaridin A synergistically enhanced TRAIL-induced cell death in TRAIL-sensitive and -resistant colon cancer cells. Additionally, proscillaridin A enhanced cell death in cells treated with TRAIL and TRAIL sensitizer, the second mitochondria-derived activator of caspase mimetic. Proscillaridin A upregulated TRAIL receptor expression, while downregulating the levels of the anti-cell death molecules, cellular FADD-like IL-1β converting enzyme-like inhibitor protein and Mcl1, in a cell type-dependent manner. Furthermore, proscillaridin A enhanced TRAIL-induced cell death partly via O-glycosylation. Taken together, our findings suggest that proscillaridin A is a promising agent that enhances the anti-cancer efficacy of TRAIL therapeutics.

Simultaneous determination of periplocin, periplocymarin, periplogenin, periplocoside M and periplocoside N of Cortex Periplocae in rat plasma and its application to a pharmacokinetic study

A sensitive and specific ultra-performance liquid chromatographic-tandem mass spectrometric method was developed and validated to simultaneously determine periplocin, periplocymarin (PM), periplogenin (PG), periplocoside M (PSM) and periplocoside N (PSN) in rat plasma. Acetonitrile was employed to precipitate plasma with appropriate sensitivity and acceptable matrix effects. Chromatographic separation was performed using a Waters HSS T3 column with a gradient elution using water and acetonitrile both containing 0.1% formic acid and 0.1 mm ammonium formate within 8 min. Detection was performed in positive ionization mode using multiple reaction monitoring. The method was fully validated in terms of selectivity, linearity, accuracy, precision, recovery, matrix effects and stability. Using this method, the concentrations of periplocin, PM, PG, PSM and PSN were established after oral administration of Cortex Periplocae extract to rats, and the pharmacokinetic characteristics of periplocin, PM, PG, PSM and PSN were assessed. Generally, PM, PG, PSM and PSN were eliminated slowly and their half-lives were all >8 h. In addition, the systemic exposure of PSM showed significant differences between genders with more than 10 times higher area under the concentration-time curve in female rats than in male rats. The findings of this study provide useful information for further research on Cortex Periplocae.

Inhibitory Effects of Periplocin on Lymphoma Cells: A Network Pharmacology Approach and Experimental Validation

Purpose

Lymphoma is considered to be one of the most pressing health problems worldwide owing to its high incidence and mortality. Previous studies have shown that periplocin, a naturally occurring compound, inhibits growth and induces apoptosis in several cancers. However, the effects of periplocin on lymphoma and the underlying mechanisms of action remain unclear.

Methods

The PharmMapper database was used to predict the potential targets of periplocin. The GeneCard database was used to identify lymphoma-related genes. A few intersecting genes were obtained, and the protein-protein interaction network was visualized using STRING Gene ontology analysis. Kyoto Encyclopedia of Genes and Genomes pathway analyses were performed using R project. MTS assay, flow cytometry, real-time quantitative polymerase chain reaction (qPCR), and Western blotting were used to verify whether periplocin possesses anti-lymphoma activity.

Results

A total of 216 intersecting genes were identified. Numerous cancer-related signaling pathways were visualized using Cytoscape software, with the PI3K-Akt signaling pathway being the highest-ranked pathway related to cell proliferation, apoptosis, and cell cycle progression. HuT 78 and Jurkat cell lines were used to verify the predictions. Periplocin significantly inhibited their proliferation in a dose- and time-dependent manner, but had no effect on the viability of peripheral blood lymphocytes. Flow cytometry revealed that treatment with periplocin increased the apoptotic rate and ratio of HuT 78 and Jurkat cells in the G2/M phase. CDK1 and cyclin B1 complex formation is a key gatekeeper to mitotic division in the G2/M phase. Western blot analysis revealed that periplocin significantly decreased the protein levels of CDK1 and cyclin B1; however, real-time qPCR revealed no effect on gene expression.

Conclusion

Periplocin showed anti-tumor effects in lymphoma cells through multiple targets and signaling pathways, and could be a novel therapeutic agent for the treatment of lymphoma.

Anti-nociceptive, anti-inflammatory and anti-arthritic activities of pregnane glycosides from the root bark of Periploca sepium Bunge

ETHNOPHARMACOLOGICAL RELEVANCE

Periploca sepium Bunge (P. sepium) is used in traditional Chinese medicine (TCM) for the treatment of autoimmune diseases, particularly rheumatoid arthritis. Periploca sepium periplosides (PePs), isolated from the root bark of P. sepium, characterized as the cardiac glycosides-free pregnane glycosides fraction, is expected to possess therapeutic potential on inflammatory arthritis.

AIM OF THE STUDY

The current study is designed to evaluate the anti-nociceptive, anti-inflammatory and anti-arthritic activities effects of the PePs.

MATERIALS AND METHODS

The anti-nociceptive activity of PePs was examined in the writhing test and hot-plate test in mice. The anti-inflammatory activity of PePs was determined by the 2, 4-dinitro-1-fluorobenzene (DNFB)-induced ear edema model and the carrageenan induced paw edema model in mice. The anti-arthritic activity of PePs was investigated by evaluating the joint inflammation and arthritis pathology in rat adjuvant induced arthritis (AIA) and murine collagen induced arthritis (CIA). Phytohaemagglutinin M (PHA-M) -elicited human peripheral blood mononuclear cells (PBMCs) were further applied to assess the suppressive activity of PePs on IFN-γ and IL-17 production.

RESULTS

PePs treatment markedly decreased the acetic acid-induced visceral nociceptive response and increased the hot-plate pain threshold. Further, oral administration of PePs exhibited anti-inflammatory activity by decreasing DNFB-induced ear edema in mice and carrageenan-induced paw edema in rats. Moreover, oral treatment of PePs ameliorated joint swelling and attenuated bone erosion in rodent arthritis, and the therapeutic benefits were partially attributed to the suppression of proinflammatory cytokines such IFN-γ and IL-17. Moreover, PePs suppressed the proliferation as well as IFN-γ and IL-17 secretion in PHA-M-elicited human PBMCs in a concentration dependent manner.

CONCLUSIONS

Taken together, our results justified the traditional use of Periploca sepium Bunge for the treatment of diseases associated with inflammation and pain.

Periplocin inhibits the growth of pancreatic cancer by inducing apoptosis via AMPK-mTOR signaling

BACKGROUND

Periplocin is a monomeric compound that exhibits anti-tumor activities. It is extracted from Cortex Periplocae.

OBJECTIVE

This study aimed at determining the effect of periplocin treatment on the apoptosis and proliferation of human pancreatic cancer cells, and to elucidate on its mechanisms of action.

METHODS

PANC1 and cfpac1 cells were treated with periplocin. Cell proliferation was detected by RTCA, Ki67 immunofluorescence, and a clonogenic assay. The transwell assay was used to examine cell migration and invasion functions. The expression of apoptosis-associated proteins was detected by flow cytometry and western blotting. Total RNA was extracted from the treated and untreated group of PANC1 cells for RNA-seq detection and analysis. Differentially expressed genes were screened for GO biological process and KEGG pathway analysis. Finally, CFPAC1 cells were subcutaneously inoculated into BALB / c nude mice to assess tumor growth.

RESULTS

Periplocin inhibited the proliferation of PANC1 and CFPAC1 cells and induced their apoptosis by activating the AMPK/mTOR pathway and inhibiting p70 S6K. It also attenuated the cell migration, invasion, and inhibited the growth of cfpac1 xenografts in nude mice.

CONCLUSIONS

Periplocin inhibits human pancreatic cancer cell proliferation and induces their apoptosis by activating the AMPK / mTOR pathway.

Combination of the natural compound Periplocin and TRAIL induce esophageal squamous cell carcinoma apoptosis in vitro and in vivo: Implication in anticancer therapy

BACKGROUND

Esophageal cancer is one of the most common malignant tumors in the world. With currently available therapies, only 20% ~ 30% patients can survive this disease for more than 5 years. TRAIL, a natural ligand for death receptors that can induce the apoptosis of cancer cells, has been explored as a therapeutic agent for cancers, but it has been reported that many cancer cells are resistant to TRAIL, limiting the potential clinical use of TRAIL as a cancer therapy. Meanwhile, Periplocin (CPP), a natural compound from dry root of Periploca sepium Bge, has been studied for its anti-cancer activity in a variety of cancers. It is not clear whether CPP and TRAIL can have activity on esophageal squamous cell carcinoma (ESCC) cells, or whether the combination of these two agents can have synergistic activity.

METHODS

We used MTS assay, flow cytometry and TUNEL assay to detect the effects of CPP alone or in combination with TRAIL on ESCC cells. The mechanism of CPP enhances the activity of TRAIL was analyzed by western blot, dual luciferase reporter gene assay and chromatin immunoprecipitation (ChIP) assay. The anti-tumor effects and the potential toxic side effects of CPP alone or in combination with TRAIL were also evaluated in vivo.

RESULTS

In our studies, we found that CPP alone or in combination with TRAIL could inhibit the proliferation of ESCC cells and induce apoptosis, and we certificated that combination of two agents exert synergized functions. For the first time, we identified FoxP3 as a key transcriptional repressor for both DR4 and DR5. By down-regulating FoxP3, CPP increases the expression of DR4/DR5 and renders ESCC cells much more sensitive to TRAIL. We also showed that CPP reduced the expression of Survivin by inhibiting the activity of Wnt/β-catenin pathway. All these contributed to synergistic activity of CPP and TRAIL on ESCC cells in vitro and in vivo.

CONCLUSION

Our data suggest that CPP and TRAIL could be further explored as potential therapeutic approach for esophageal cancer.

Genus Periploca (Apocynaceae): A Review of Its Classification, Phytochemistry, Biological Activities and Toxicology

The genus Periploca belongs to the family Apocynaceae, which is composed of approximately ten species of plants according to incomplete statistics. Most of these plants serve as folk medicines with a long history, especially Periploca sepium and Periploca forrestii. The botanical classifications, chemical constituents, biological activities and toxicities of the genus Periploca were summarized in the literature from 1897 to early 2019. Though the botanical classification of this genus is controversial, these species are well-known to be rich sources of diverse and complex natural products-above all, cardiac steroids and C₂₁ pregnane steroids with special structures and obvious pharmacological activities. The various crude extracts and 314 isolated metabolites from this genus have attracted much attention in intensive biological studies, indicating that they are equipped with cardiotonic, anti-inflammatory, immunosuppressive, antitumor, antimicrobial, antioxidant, insecticidal and other properties. It is noteworthy that some cardiac glycosides showed hepatotoxicity and cardiotoxicity at certain doses. Therefore, in view of the medical and agricultural value of the genus Periploca, in-depth investigations of the pharmacology in vivo, the mechanisms of biological actions, and the pharmacokinetics of the active ingredients should be carried out in the future. Moreover, in order to ensure the safety of clinical medication, the potential toxicities of cardiac glycosides or other compounds should also be paid attention. This systematic review provides an important reference base for applied research on pharmaceuticals and pesticides from this genus.

Antitumor Effect of Periplocin in TRAIL-Resistant gastric cancer cells via upregulation of death receptor through activating ERK1/2-EGR1 pathway

Tumor necrosis factor-related apoptosis-inducing ligand (TRAIL), a member of the tumor necrosis factor family, induces apoptosis in a variety of cancer cells. However, gastric cancer (GC) cells are insensitive to TRAIL usually. In the previous study, we showed that Periplocin could induce apoptosis in GC cells via the activation of ERK1/2-EGR1 pathway. In the present study, we have shown that the combination of Periplocin and TRAIL had a greater inhibitory effect on gastric cancer cell viability in vitro and in vivo than Periplocin or TRAIL alone. Through upregulating the expression of DR4 and DR5 at transcriptional and protein levels, Periplocin enhanced the sensitivity of gastric cancer cells to TRAIL. Furthermore, enhanced activity of ERK1/2-EGR1 pathway was responsible for upregulating of DR4 and DR5 uponPeriplocin treatment, subsequently reducing the expression of Mcl-1 and Bcl2 and activating Bid and caspase-3/8. Collectively, these data implied that Periplocin might act as a sensitizer of TRAIL and could be a potential strategy for the treatment of GC.

An LC-MS/MS Method for Simultaneous Determination of the Toxic and Active Components of Cortex Periplocae in Rat Plasma and Application to a Pharmacokinetic Study

A sensitive and simple liquid chromatography-tandem mass spectrometry (LC-MS/MS) method was developed and validated to simultaneously determine the toxic and other active components including isovanillin, scopoletin, periplocin, periplogenin, and periplocymarin after oral administration of cortex periplocae extract to rats. Plasma samples were prepared by protein precipitation with methanol. All compounds were separated on a C₁₈ column with gradient elution using acetonitrile and formic acid aqueous solution (0.1%, v/v) as the mobile phase at a flow rate of 0.3 mL/min. The detection of all compounds was accomplished by multiple-reaction monitoring (MRM) in the positive electrospray ionization mode. The LC-MS/MS method exhibited good linearity for five analytes. The lower limit of quantification (LLOQ) was 0.48 ng/mL for scopoletin, periplogenin, and periplocymarin; 2.4 ng/mL for isovanillin and periplocin. The extraction recoveries of all compounds were more than 90% and the RSDs were below 10%. It was found that the absorption of scopoletin and periplocin was rapid in vivo after oral administration of cortex periplocae extract. Furthermore, periplocymarin possessed abundant plasma exposure. The results demonstrated that the validated method was efficiently applied for the pharmacokinetic studies of isovanillin, scopoletin, periplocin, periplogenin, and periplocymarin after oral administration of cortex periplocae extract.

Periploca forrestii saponin ameliorates CIA via suppressing proinflammatory cytokines and nuclear factor kappa-B pathways

OBJECTIVE

Periploca forrestii Schltr has been used as a Chinese folk medicine for the treatment of rheumatism, arthralgia and fractures. However, the anti-arthritic activity of Periploca forrestii saponin (PFS) and the active compound has still not been revealed. This study aimed to investigate the protective effects and mechanisms of PFS on collagen type II (CII) collagen-induced arthritis (CIA) mice. We sought to investigate whether PFS and Periplocin could regulate osteoclastogenesis, and if so, further investigation on its mechanism of action.

METHODS

Arthritis was induced in female BALB/c mice by CIA method. PFS was administered at a dose of 50 mg/kg body weight once daily for five weeks. The effects of treatment in mice were assessed by histological and biochemical evaluation in sera and paws. Anti-osteoclastogenic action of PFS and Periplocin was identified using an osteoclast formation model induced by RANKL.

RESULTS

PFS ameliorated paw erythema and swelling, inhibited bone erosion in ankle joint histopathological examination. PFS treatment resulted in decreased IgG2a, and increased IgG1 levels in the serum of CIA mice. Decreased TNF-α, and increased interleukin (IL)-4 and IL-22 levels were also found in PFS-treated mice. PFS inhibited the I-κBα phosphorylation, blocked nuclear factor (NF)-κB/p65 phosphorylation and abrogated AP-1/c-Fos activity. PFS downregulated toll-like receptor (TLR) 4, STAT3 and MMP-9 expression in CIA mice and RANKL-induced osteoclastogenesis. PFS and Periplocin inhibited RANKL-induced osteoclast formation in a dose dependent manner within nongrowth inhibitory concentration, and PFS decreased osteoclastogenesis-related marker expression, including cathepsin K and MMP-9.

CONCLUSION

This study revealed that the protective mechanism of PFS on CIA was associated with regulatory effects on proinflammatory factors and further on the crosstalk between NF-κB and c-Fos/AP-1 in vivo and in vitro. Therefore, PFS is a promising therapeutic alternative for the treatment of RA, evidencing the need to conduct further studies that can identify their active components in treating and preventing RA.

Periploca forrestii Saponin Ameliorates Murine CFA-Induced Arthritis by Suppressing Cytokine Production

Periploca forrestii Schltr. has been used as a Chinese folk medicine due to its versatile pharmacological effects such as promoting wounds and rheumatoid arthritis. However, the antiarthritic activity of Periploca forrestii saponin (PFS) and its active compound Periplocin has still not been demonstrated. Here, we evaluated the antiarthritic effects of PFS in adjuvant-induced arthritis (AIA) rats by intragastric administration at a dose of 50 mg/kg. The anti-inflammatory activities of Periplocin were also examined in LPS-induced AIA splenocytes and synoviocytes. PFS significantly ameliorated joint swelling; inhibited bone erosion in joints; lowered levels of IL-6 and TGF-β1 in AIA rat splenocyte; and reduced joint protein expression levels of phospho-STAT3 and IKKα. Using LPS-induced AIA splenocytes, we demonstrate that Periplocin suppressed the key proinflammatory cytokines levels of IL-6, IFN-γ, TGF-β1, and IL-13 and IL-22 and transcription factor levels of T-bet, GATA3, and C-Jun genes. Periplocin also suppressed LPS-induced cytokine secretion from synoviocytes. Our study highlights the antiarthritic activity of PFS and its derived Periplocin and the underlying mechanisms. These results provide a strong rationale for further testing and validation of the use of Periploca forrestii Schltr. as an alternative modality for the treatment of RA.

A Review on Phytochemistry and Pharmacology of Cortex Periplocae

Cortex Periplocae, as a traditional Chinese herbal medicine, has been widely used for autoimmune diseases, especially rheumatoid arthritis. Due to its potential pharmaceutical values, more studies about the biological activities of Cortex Periplocae have been conducted recently. Meanwhile, the adverse reaction of Cortex Periplocae is not a negligible problem in clinic. In this article, we reviewed a series of articles and summarized the recent studies of Cortex Periplocae in the areas of phytochemistry and pharmacology. More than 100 constituents have been isolated and identified from Cortex Periplocae, including steroids, cardiac glycosides, terpenoids, and fatty acid compounds. The crude extracts of Cortex Periplocae and its active compounds exhibit various biological activities, such as cardiotonic effect, anticancer action, and anti-inflammatory effect. This paper aims to provide an overall review on the bioactive ingredients, pharmacological effect, and toxicity of this plant. Furthermore, this review suggests investigating and developing new clinical usages according to the above pharmacological effects.

Glycogen synthase kinase-3β regulates tumor necrosis factor-related apoptosis inducing ligand (TRAIL)-induced apoptosis via the NF-κB pathway in hepatocellular carcinoma

Tumor necrosis factor (TNF)-related apoptosis-inducing ligand (TRAIL) is known for its ability to selectively induce apoptosis in malignant cells. However, human hepatocellular carcinoma (HCC) cells display resistance to TRAIL-induced cell death. The present study investigated whether TRAIL-induced apoptosis in HCC cells was enhanced by the administration of an inhibitor of glycogen synthase kinase-3β (GSK-3β) or by short hairpin RNA-mediated inhibition of GSK-3β. The results of the current study demonstrated that inhibition of GSK-3β significantly impairs the expression of the nuclear factor-κB (NF-κB) target genes Bcl-xL and clAP2 in HCC cells (P<0.05). This indicates that GSK-3β may regulate NF-κB target genes involved in cell survival. Furthermore, knockdown of Bcl-xL significantly enhanced the sensitizing effect of GSK-3β inhibitor on TRAIL-induced apoptosis (P<0.05). Overall, the present study provides a rationale for further exploration of GSK-3β inhibition combined with TRAIL as a novel treatment for HCC.

Hepatocellular carcinoma: targeting of oncogenic signaling networks in TRAIL resistant cancer cells

Apoptotic response in hepatocellular carcinoma (HCC) cells is impaired because of interconnectivity of proteins into complexes and signaling networks that are highly divergent in time and space. TNF-related apoptosis-inducing ligand (TRAIL) has emerged as an attractive anticancer agent reported to selectively induce apoptosis in cancer cells. Although diametrically opposed roles of TRAIL are reported both as an inducer of apoptosis and regulator of metastasis, overwhelmingly accumulating experimental evidence highlighting apoptosis inducing activity of TRAIL is directing TRAIL into clinical trials. Insights from TRAIL mediated signaling in HCC research are catalyzing new lines of study that should not only explain molecular mechanisms of disease but also highlight emerging paradigms in restoration of TRAIL mediated apoptosis in resistant cancer cells. It is becoming progressively more understandable that phytochemicals derived from edible plants have shown potential in modelling their interactions with their target proteins. Rapidly accumulating in vitro and in-vivo evidence indicates that phytonutrients have anticancer activity in rodent models of hepatocellular carcinoma. In this review we bring to limelight how phytonutrients restore apoptosis in hepatocellular carcinoma cells by rebalancing pro-apoptotic and anti-apoptotic proteins. Evidence has started to emerge, that reveals how phytonutrients target pharmacologically intractable proteins to suppress cancer. Target-based small-molecule discovery has entered into the mainstream research in the pharmaceutical industry and a better comprehension of the genetics of patients will be essential for identification of responders and non-responders.

Evaluating the cancer therapeutic potential of cardiac glycosides

Cardiac glycosides, also known as cardiotonic steroids, are a group of natural products that share a steroid-like structure with an unsaturated lactone ring and the ability to induce cardiotonic effects mediated by a selective inhibition of the Na⁺/K⁺-ATPase. Cardiac glycosides have been used for many years in the treatment of cardiac congestion and some types of cardiac arrhythmias. Recent data suggest that cardiac glycosides may also be useful in the treatment of cancer. These compounds typically inhibit cancer cell proliferation at nanomolar concentrations, and recent high-throughput screenings of drug libraries have therefore identified cardiac glycosides as potent inhibitors of cancer cell growth. Cardiac glycosides can also block tumor growth in rodent models, which further supports the idea that they have potential for cancer therapy. Evidence also suggests, however, that cardiac glycosides may not inhibit cancer cell proliferation selectively and the potent inhibition of tumor growth induced by cardiac glycosides in mice xenografted with human cancer cells is probably an experimental artifact caused by their ability to selectively kill human cells versus rodent cells. This paper reviews such evidence and discusses experimental approaches that could be used to reveal the cancer therapeutic potential of cardiac glycosides in preclinical studies.

The Inhibitory Effect of 3 β -Hydroxy-12-oleanen-27-oic Acid on Growth and Motility of Human Hepatoma HepG2 Cells through JNK and Akt Signaling Pathway

3 β -Hydroxy-12-oleanen-27-oic acid (ATA) was a main antitumor active triterpene from the rhizomes of Astilbe chinensis. In this study, we investigated its effects on growth, apoptosis, cell cycle, motility/invasion, and metatasis in human hepatoma HepG2 cells in vitro and antimetastasis of B16-F10 melanoma in mice in vivo, as well as its molecular mechanisms of action using a high-throughput Cancer Pathway Finder PCR Array. ATA could not only induce tumor cells into apoptosis through the activation of both extrinsic and intrinsic pathways, arrest HepG2 cells in G2/M phase, but also suppress the invasion and metastasis abilities of HepG2 cells and the lung metastasis of B16-F10 melanoma in mice. PCR array assay revealed that ATA upregulated 9 genes including CDKN1A, MDM2, CFLAR (CASPER), TNFRSF10B (DR5), c-Jun, IL-8, THBS1, SERPINB5 (maspin), and TNF and downregulated 8 genes such as CCNE1, AKT, ANGPT1, TEK, TGFBR1, MMP9, U-PA, and S100A4. These results indicate that ATA could exert antitumor effects through activating JNK/MAPK and suppressing AKT signal transduction pathways and that ATA might be a potent anticancer agent.