Pristimerin Induces Apoptosis in Prostate Cancer Cells by Down-regulating Bcl-2 through ROS-dependent Ubiquitin-proteasomal Degradation Pathway

Pristimerin Exerts Pharmacological Effects Through Multiple Signaling Pathways: A Comprehensive Review

Pristimerin, a natural triterpenoid isolated from the plants of southern snake vine and Maidenwood in the family Weseraceae, is anti-inflammatory, insecticidal, antibacterial, and antiviral substance and has been used for its cardioprotective and antitumor effects and in osteoporosis treatment. These qualities explain Pristimerin's therapeutic effects on different types of tumors and other diseases. More and more studies have shown that pristimerin acts in a wide range of biological activities and has shown great potential in various fields of modern and Chinese medicine. While Pristimerin's wide range of pharmacological effects have been widely studied by others, our comprehensive review suggests that its mechanism of action may be through affecting fundamental cellular events, including blocking the cell cycle, inducing apoptosis and autophagy, and inhibiting cell migration and invasion, or through activating or inhibiting certain key molecules in several cell signaling pathways, including nuclear factor κB (NF-κB), phosphatidylinositol 3-kinase/protein kinase B/mammalian-targeted macromycin (PI3K/Akt/mTOR), mitogen-activated protein kinases (MAPKs), extracellular signal-regulated protein kinase 1/2 (ERK1/2), Jun amino-terminal kinase (JNK1/2/3), reactive oxygen species (ROS), wingless/integrin1 (Wnt)/β-catenin, and other signaling pathways. This paper reviews the research progress of Pristimerin's pharmacological mechanism of action in recent years to provide a theoretical basis for the molecular targeting therapy and further development and utilization of Pristimerin. It also provides insights into improved treatments and therapies for clinical patients and the need to explore pristimerin as a potential facet of treatment.

PKC is an indispensable factor in promoting environmental toxin chromium-mediated transformation and drug resistance

Hexavalent chromium [Cr(VI)] pollution is a serious environmental problem, due to not only its toxicity but also carcinogenesis. Although studies reveal several features of Cr(VI)-induced carcinogenesis, the underlying mechanisms of how Cr(VI) orchestrates multiple mitogenic pathways to promote tumor initiation and progression remain not fully understood. Src/Ras and other growth-related pathways are shown to be key players in Cr(VI)-initiated tumor prone actions. The role of protein kinase C (PKC, an important signal transducer) in Cr(VI)-mediated carcinogenesis has not been thoroughly investigated. In this study, using human bronchial/lung epithelial cells and keratinocytes, we demonstrate that PKC activity is increased by transient or chronic Cr(VI) exposure, which plays no role in the activation of Src/Ras signaling and ROS upregulation by this metal toxin. PKC in chronic Cr(VI)-treated cells stabilizes Bcl-2 to mitigate doxorubicin (an anti-cancer drug)-mediated apoptosis. After the suppression of this kinase by GO6976 (a PKC inhibitor), the cells chronically exposed to Cr(VI) partially regain the sensitivity to doxorubicin. However, when co-suppressed PKC and Ras, the chronic Cr(VI)-treated cells become fully responsive to doxorubicin and are unable to be transformed. Taken together, our study provides a new insight into the mechanisms, in which PKC is an indispensable player and cooperates with other mitogenic pathways to achieve Cr(VI)-induced carcinogenesis as well as to establish drug resistance. The data also suggest that active PKC can serve as a potential biomarker for early detection of health damages by Cr(VI) and therapeutic target for developing new treatments for diseases caused by Cr(VI).

Natural Products as the Modulators of Oxidative Stress: An Herbal Approach in the Management of Prostate Cancer

Prostate cancer is the most commonly diagnosed and frequently occurred cancer in the males globally. The current treatment strategies available to treat prostate cancer are not much effective and express various adverse effects. Hence, there is an urgent need to identify novel treatment that can improve patient outcome. From times immemorial, natural products are highly recognized for novel drug development for various diseases including cancer. Cancer cells generally maintain higher basal levels of reactive oxygen species (ROS) when compared to normal cells due to its high metabolic rate. However, initiation of excess intracellular ROS production can not be tolerated by the cancer cells and induce several cell death signals which are in contrast to normal cells. Therefore, small molecules of natural origin that induce ROS can potentially kill cancer cells in specific and provide a better opportunity to develop a novel drug therapy. In this review, we elaborated various classes of medicinal compounds and their mechanism of killing prostate cancer cells through direct or indirect ROS generation. This can generate a novel thought to develop promising drug candidate to treat prostate cancer patients.

Cellular and Molecular Mechanisms of Pristimerin in Cancer Therapy: Recent Advances

Seeking an efficient and safe approach to eliminate tumors is a common goal of medical fields. Over these years, traditional Chinese medicine has attracted growing attention in cancer treatment due to its long history. Pristimerin is a naturally occurring quinone methide triterpenoid used in traditional Chinese medicine to treat various cancers. Recent studies have identified alterations in cellular events and molecular signaling targets of cancer cells under pristimerin treatment. Pristimerin induces cell cycle arrest, apoptosis, and autophagy to exhibit anti-proliferation effects against tumors. Pristimerin also inhibits the invasion, migration, and metastasis of tumor cells via affecting cell adhesion, cytoskeleton, epithelial-mesenchymal transition, cancer stem cells, and angiogenesis. Molecular factors and pathways are associated with the anti-cancer activities of pristimerin. Furthermore, pristimerin reverses multidrug resistance of cancer cells and exerts synergizing effects with other chemotherapeutic drugs. This review aims to discuss the anti-cancer potentials of pristimerin, emphasizing multi-targeted biological and molecular regulations in cancers. Further investigations and clinical trials are warranted to understand the advantages and disadvantages of pristimerin treatment much better.

Pristimerin Suppresses Trophoblast Cell Epithelial-Mesenchymal Transition via miR-542-5p/EGFR Axis

Background

Ectopic pregnancy (EP) is an ectopic embryo implantation occurred outside the uterine cavity. Nowadays, more attention have garnered in fast and effective treatment with less side effects. Pristimerin is known as the clinical application for anti-cancer, and the effect on EP therapy is still unclear.

Materials and Methods

Trophoblast cell line HTR-8/SVneo was used; then, we performed cell counting kit-8 assay, wound healing assay, flow cytometry and real-time polymerase chain reaction analysis (RT-PCR) to detect the cell viability, migration ability, apoptosis and epithelial–mesenchymal transition (EMT) under pristimerin treatment. In addition, public bioinformatic database was used to discover the connection between molecular and genes. Finally, we used miRNA transfection and RT-PCR techniques to determine the underlying molecular mechanism.

Results

We revealed that pristimerin inhibited trophoblast cells proliferation, migration and EMT, while induced trophoblast cell apoptosis. Furthermore, expression of miR-542-5p, AGO2 and EGFR was suppressed in HTR-8/SVneo cells post pristimerin treatment, and miR-542-5p silence showed the same effect. Combing pristimerin treatment and miR-542-5p silence showed a synergistic action.

Conclusion

Pristimerin could be an effective treatment to block embryo implantation by miR-542-5p and EGFR down-regulation.

Pristimerin Inhibits MMP-9 Expression and Cell Migration Through Attenuating NOX/ROS-Dependent NF-κB Activation in Rat Brain Astrocytes Challenged with LPS

Purpose

Neuroinflammation plays a crucial role in neurodegenerative diseases. Matrix metalloproteinases (MMPs) are a landmark of neuroinflammation. Lipopolysaccharide (LPS) has been demonstrated to induce MMP-9 expression. The mechanisms underlying LPS-induced MMP-9 expression have not been completely elucidated in astrocytes. Nuclear factor-kappaB (NF-κB) is well known as one of the crucial transcription factors in MMP-9 induction. Moreover, reactive oxygen species (ROS) could be an important mediator of neuroinflammation. Here, we differentiated whether ROS and NF-κB contributed to LPS-mediated MMP-9 expression in rat brain astrocytes (RBA-1). Besides, pristimerin has been revealed to possess antioxidant and anti-inflammatory effects. We also evaluated the effects of pristimerin on LPS-induced inflammatory responses.

Methods

RBA-1 cells were used for analyses. Pharmacological inhibitors and siRNAs were used to evaluate the signaling pathway. Western blotting and gelatin zymography were conducted to evaluate protein and MMP-9 expression, respectively. Real-time PCR was for mRNA expression. Wound healing assay was for cell migration. 2',7'-dichlorodihydrofluorescein diacetate (H₂DCF-DA) and dihydroethidium (DHE) staining were for ROS generation. Immunofluorescence staining was conducted to assess NF-κB p65. Promoter-reporter gene assay and chromatin immunoprecipitation (ChIP) assay were used to detect promoter activity and the association of nuclear proteins with the promoter.

Results

Our results showed that the increased level of ROS generation was attenuated by edaravone (a ROS scavenger), apocynin (APO; an inhibitor of p47^Phox), diphenyleneiodonium (DPI; an inhibitor of NOX), and pristimerin in RBA-1 cells exposed to LPS. Besides, pretreatment with APO, DPI, edaravone, Bay11-7082, and pristimerin also inhibited the phosphorylation, nuclear translocation, promoter binding activity of NF-κB p65 as well as upregulation of MMP-9 expression-mediated cell migration in RBA-1 cells challenged with LPS.

Conclusion

These results suggested that LPS enhances the upregulation of MMP-9 through nicotinamide adenine dinucleotide phosphate (NADPH) oxidase (NOX)/ROS-dependent NF-κB activity. These results also provide new insights into the mechanisms by which pristimerin attenuates LPS-mediated MMP-9 expression and neuroinflammatory responses.

Pristimerin Suppressed Breast Cancer Progression via miR-542-5p/DUB3 Axis

BACKGROUND

Breast cancer is one of the most common and malignant tumors in the world. Nowadays more attention has been garnered in pristimerin anti-cancer effects. Here, we illustrate the function and regulatory mechanism of pristimerin in breast cancer therapy.

MATERIALS AND METHODS

Breast cancer cell lines MCF-7, MDA-MB-231, and 4T1 were used. Cell Counting Kit-8 (CCK-8) assay was performed to evaluate proliferation viability of breast cancer cells under pristimerin treatment. Wound healing assay was used to examine the migration ability, cell cycle, and cell apoptosis detection were tested by flow cytometry. Bioinformatic analysis was used to find the underlying molecular and gene connected with pristimerin and breast cancer survival. Finally, we used transfection and real-time polymerase chain reaction analysis to confirm the mechanism.

RESULTS

We observed that pristimerin inhibited breast cancer cell viability, migration, and cell cycle, meanwhile induced cell apoptosis. In addition, under pristimerin treatment, miR-542-5p was up-regulated while DUB3 was down-regulated. Furthermore, bioinformatics analysis showed higher expression of DUB3 in breast cancer compared with normal tissue, also with poor prognosis. Overexpression miR-542-5p in breast cancer cells leads to a decrease in DUB3 level. The effect was obviously post pristimerin treatment and miR-542-5p overexpression.

CONCLUSION

Pristimerin inhibited breast cancer progression through DUB3 expression via a canonical miRNA-mediated mechanism.

Terpenoids, Cannabimimetic Ligands, beyond the Cannabis Plant

Medicinal use of Cannabis sativa L. has an extensive history and it was essential in the discovery of phytocannabinoids, including the Cannabis major psychoactive compound-Δ9-tetrahydrocannabinol (Δ9-THC)-as well as the G-protein-coupled cannabinoid receptors (CBR), named cannabinoid receptor type-1 (CB1R) and cannabinoid receptor type-2 (CB2R), both part of the now known endocannabinoid system (ECS). Cannabinoids is a vast term that defines several compounds that have been characterized in three categories: (i) endogenous, (ii) synthetic, and (iii) phytocannabinoids, and are able to modulate the CBR and ECS. Particularly, phytocannabinoids are natural terpenoids or phenolic compounds derived from Cannabis sativa. However, these terpenoids and phenolic compounds can also be derived from other plants (non-cannabinoids) and still induce cannabinoid-like properties. Cannabimimetic ligands, beyond the Cannabis plant, can act as CBR agonists or antagonists, or ECS enzyme inhibitors, besides being able of playing a role in immune-mediated inflammatory and infectious diseases, neuroinflammatory, neurological, and neurodegenerative diseases, as well as in cancer, and autoimmunity by itself. In this review, we summarize and critically highlight past, present, and future progress on the understanding of the role of cannabinoid-like molecules, mainly terpenes, as prospective therapeutics for different pathological conditions.

Redox Balance Keepers and Possible Cell Functions Managed by Redox Homeostasis in Trypanosoma cruzi

The toxicity of oxygen and nitrogen reactive species appears to be merely the tip of the iceberg in the world of redox homeostasis. Now, oxidative stress can be seen as a two-sided process; at high concentrations, it causes damage to biomolecules, and thus, trypanosomes have evolved a strong antioxidant defense system to cope with these stressors. At low concentrations, oxidants are essential for cell signaling, and in fact, the oxidants/antioxidants balance may be able to trigger different cell fates. In this comprehensive review, we discuss the current knowledge of the oxidant environment experienced by T. cruzi along the different phases of its life cycle, and the molecular tools exploited by this pathogen to deal with oxidative stress, for better or worse. Further, we discuss the possible redox-regulated processes that could be governed by this oxidative context. Most of the current research has addressed the importance of the trypanosomes' antioxidant network based on its detox activity of harmful species; however, new efforts are necessary to highlight other functions of this network and the mechanisms underlying the fine regulation of the defense machinery, as this represents a master key to hinder crucial pathogen functions. Understanding the relevance of this balance keeper program in parasite biology will give us new perspectives to delineate improved treatment strategies.

Anti-Cancer Effects of Pristimerin and the Mechanisms: A Critical Review

As a quinonemethide triterpenoid extracted from species of the Celastraceae and Hippocrateaceae, pristimerin has been shown potent anti-cancer effects. Specifically, it was found that pristimerin can affect many tumor-related processes, such as apoptosis, autophagy, migration and invasion, vasculogenesis, and drug resistance. Various molecular targets or signaling pathways are also involved, such as cyclins, reactive oxygen species (ROS), microRNA, nuclear factor kappa B (NF-κB), mitogen-activated protein kinase (MAPK), and PI3K/AKT/mammalian target of rapamycin (mTOR) pathways. In this review, we will focus on the research about pristimerin-induced anti-cancer activities to achieve a deeper understanding of the targets and mechanisms, which offer evidences suggesting that pristimerin can be a potent anti-cancer drug.

Pristimerin inhibits glioma progression by targeting AGO2 and PTPN1 expression via miR-542-5p

Glioblastoma multiform is the most common and malignant primary tumor of the central nervous system in adults, the high recurrence rate and poor prognosis are critical priorities. Pristimerin is a naturally occurring quinone methide triterpenoid isolated from the Celastraceae and Hippocrateaceae families. Its anticancer effects have garnered considerable attention; nonetheless, the mechanisms of action remain unknown. To predict the hub genes of pristimerin, PharmMapper and the Coremine database were used to identify 13 potential protein targets; protein-protein interaction, for which functional enrichment analyses were performed. Compound-target, target-pathway, and compound-target-pathway networks were constructed using Cytoscape. Biological process analysis first revealed that enrichment of these target genes correlated with negative regulation of symbiont growth in the host, and regulation of chronic inflammatory response to antigenic stimulus. Survival analysis in cBioPortal showed that protein tyrosine phosphatase, non-receptor type 1 (PTPN1) and Argonaute 2 (AGO2) might be involved in the carcinogenesis, invasion, or recurrence of diffuse glioma. In addition, we observed that low-dose pristimerin inhibited the viability of glioma cells, while miR-542-5p in vitro; and reduced PTPN1 expression. Notably, high-dose pristimerin induced apoptosis. Furthermore, miR-542-5p silence with siRNA in glioma cells lead to the elevation in AGO2, and decreased PTPN1 level. The effect was obviously post pristimerin treatment and miR-542-5p suppression. In conclusion, pristimerin inhibited glioma progression through AGO2 and PTPN1 expression via a canonical miRNA-mediated mechanism.

Pristimerin enhances the effect of cisplatin by inhibiting the miR‑23a/Akt/GSK3β signaling pathway and suppressing autophagy in lung cancer cells

Lung cancer is a common type of cancer with a high mortality rate in China. Cisplatin (Cis) is one of the most effective broad‑spectrum chemotherapeutic drugs for the treatment of advanced lung cancer. However, Cis resistance remains an obstacle in the treatment of advanced lung cancer. Pristimerin (Pris), a naturally occurring triterpenoid quinone compound, not only possesses anticancer properties, but also enhances chemosensitivity. Therefore, the present study aimed to investigate whether Pris can enhance the chemosensitivity of lung cancer cells to Cis and identify the underlying mechanism. A Cell Counting kit‑8 and flow cytometry were used to determine cell viability, cell cycle progression and apoptosis in A549 and NCI‑H446 cells. Western blotting was used to determine cell apoptosis‑related, cell cycle‑related and autophagy‑related proteins. The results showed that Pris inhibited cell proliferation, and induced G0/G1 arrest and cell apoptosis in A549 and NCI‑H446 cells. The western blotting revealed that Pris effectively synergized with Cis to induce cell apoptosis by inhibiting the microRNA‑23a/Akt/glycogen synthase kinase 3β signaling pathway and suppressing autophagy. In vivo xenograft experiments confirmed that Pris effectively synergized with Cis to suppress tumor growth. Collectively, these results indicate that Pris synergized with Cis and that this may be a potential therapeutic strategy to overcome lung cancer.

Pristimerin induces apoptosis of oral squamous cell carcinoma cells via G1 phase arrest and MAPK/Erk1/2 and Akt signaling inhibition

Pristimerin is an active compound isolated from the traditional Chinese herbs Celastraceae and Hippocrateaceae. It has been reported to exert antitumor effects under experimental and clinical conditions; however, the antitumor effects and underlying mechanisms of pristimerin in oral cancer cells have not yet been identified. In the present study, the anticancer potential of pristimerin was investigated in two oral squamous cell carcinoma (OSCC) cell lines, CAL-27 and SCC-25. Results demonstrated that pristimerin was toxic against the two cell lines, and exhibited inhibitory effects against proliferation. Furthermore, pristimerin exhibited a more potent anti-proliferative activity in CAL-27 and SCC-25 cells than the common chemotherapy drugs cisplatin and 5-fluorouracil. In addition, cell cycle distribution analysis revealed that G₀/G₁ phase arrest was induced following pristimerin treatment in CAL-27 and SCC-25 cells, which was strongly associated with upregulation of p21 and p27, coupled with downregulation of cyclin D1 and cyclin E. Meanwhile, pristimerin induced significant apoptosis of CAL-27 and SCC-25 cells, alongside decreased levels of caspase-3 and specific cleavage of poly (ADP-ribose) polymerase. These effects were associated with inhibition of the mitogen-activated protein kinase/extracellular signal-regulated kinase 1/2 and protein kinase B signaling pathways. With regards to these results, pristimerin may be considered a potent novel active substance for the treatment of OSCC.

Antioxidative CXXC Peptide Motif From Mesencephalic Astrocyte-Derived Neurotrophic Factor Antagonizes Programmed Cell Death

Mesencephalic astrocyte-derived neurotrophic factor (MANF) is a potent survival-promoting protein with neurorestorative effect for neurodegenerative diseases. Its mechanism of action, albeit poorly known, depends strongly on the CXXC motif (CKGC). Here we studied the survival-promoting properties of the CKGC tetrapeptide from MANF. In the Jurkat T lymphocytic cell line, CKGC potently inhibits death receptor Fas-induced apoptosis and mildly counteracts mitochondrial apoptosis and necroptosis. The peptide with serines instead of cysteines (SKGS) has no survival-promoting activity. The cytoprotective efficiency of the peptide against Fas-induced apoptosis is significantly improved by reduction of its cysteines by dithiotreitol, suggesting that it protects the cells via cysteine thiol groups, partially as an antioxidant. CKGC neutralizes the reactive oxygen species, maintains the mitochondrial membrane potential and prevents activation of the effector caspases in the Jurkat cells with activated Fas. The peptide does not require intracellular administration, as it is endocytosed and resides mainly in the Golgi. Finally, the peptide also potently promotes survival of cultured primary dopaminergic neurons.

Exogenous H2S facilitating ubiquitin aggregates clearance via autophagy attenuates type 2 diabetes-induced cardiomyopathy

Diabetic cardiomyopathy (DCM) is a serious complication of diabetes. Hydrogen sulphide (H₂S), a newly found gaseous signalling molecule, has an important role in many regulatory functions. The purpose of this study is to investigate the effects of exogenous H₂S on autophagy and its possible mechanism in DCM induced by type II diabetes (T2DCM). In this study, we found that sodium hydrosulphide (NaHS) attenuated the augment in left ventricular (LV) mass and increased LV volume, decreased reactive oxygen species (ROS) production and ameliorated H₂S production in the hearts of db/db mice. NaHS facilitated autophagosome content degradation, reduced the expression of P62 (a known substrate of autophagy) and increased the expression of microtubule-associated protein 1 light chain 3 II. It also increased the expression of autophagy-related protein 7 (ATG7) and Beclin1 in db/db mouse hearts. NaHS increased the expression of Kelch-like ECH-associated protein 1 (Keap-1) and reduced the ubiquitylation level in the hearts of db/db mice. 1,4-Dithiothreitol, an inhibitor of disulphide bonds, increased the ubiquitylation level of Keap-1, suppressed the expression of Keap-1 and abolished the effects of NaHS on ubiquitin aggregate clearance and ROS production in H9C2 cells treated with high glucose and palmitate. Overall, we concluded that exogenous H₂S promoted ubiquitin aggregate clearance via autophagy, which might exert its antioxidative effect in db/db mouse myocardia. Moreover, exogenous H₂S increased Keap-1 expression by suppressing its ubiquitylation, which might have an important role in ubiquitin aggregate clearance via autophagy. Our findings provide new insight into the mechanisms responsible for the antioxidative effects of H₂S in the context of T2DCM.

Combinatorial effect of curcumin with docetaxel modulates apoptotic and cell survival molecules in prostate cancer

Docetaxel is the most commonly used chemotherapeutic agent to target androgen signaling in metastatic prostate cancer (PCa); however, prolonged treatment with docetaxel results in drug-resistant cancer cells. Combination therapies have the potential of increasing the effectiveness of drug treatment as well as decreasing the side effects. Curcumin is a nontoxic organic compound with multifaceted chemopreventive potential. In this study, we evaluated whether curcumin can reinforce the effect of docetaxel on PCa cells. The PCa cell lines DU145 and PC3 were treated with curcumin and docetaxel alone or in combination. After completion of the treatment cell proliferation and the expression of pro-survival and anti-apoptotic markers and the signaling molecules were analyzed. The combined treatment of curcumin and docetaxel inhibited the proliferation and induced apoptosis significantly higher than the curcumin and docetaxel-treated group alone. Interestingly, the combined treatment with curcumin and docetaxel modulates the expression of RTKs, PI3K, phospho-AKT, NF-kappa B, p53, and COX-2. These results suggest that curcumin can be a potential therapeutic contender in enhancing the efficacy of docetaxel in PCa treatment.

Compounds From Celastraceae Targeting Cancer Pathways and Their Potential Application in Head and Neck Squamous Cell Carcinoma: A Review

Squamous cell carcinoma of the head and neck is one of the most common cancer types worldwide. It initiates on the epithelial lining of the upper aerodigestive tract, at most instances as a consequence of tobacco and alcohol consumption. Treatment options based on conventional therapies or targeted therapies under development have limited efficacy due to multiple genetic alterations typically found in this cancer type. Natural products derived from plants often possess biological activities that may be valuable in the development of new therapeutic agents for cancer treatment. Several genera from the family Celastraceae have been studied in this context. This review reports studies on chemical constituents isolated from species from the Celastraceae family targeting cancer mechanisms studied to date. These results are then correlated with molecular characteristics of head and neck squamous cell carcinoma in an attempt to identify constituents with potential application in the treatment of this complex disease at the molecular level.

Pristimerin inhibits growth and induces apoptosis of gastric cancer MGC803 and SGC7901 cells

AIM: To investigate the effects of pristimerin on the growth and apoptosis of gastric cancer MGC803 and SGC7901 cells, and to preliminarily explore its action mechanism.

METHODS: MGC803 and SGC7901 cells were cultured in vitro. After treatment with pristimerin, CCK-8 assay, Annexin V-FITC/PI staining, and cell cycle analysis were conducted to investigate the effects of pristimerin on the growth and apoptosis of MGC803 and SGC7901 cells, and then the mitochondrial membrane potential and Bax and Bcl-2 protein expression were determined by Rhodamine 123 staining and Western blot, respectively. Human gastric cancer MGC803 cells were transplanted to nude mice to establish an animal model, and the effect of pristimerin on tumor growth in this model was observed.

RESULTS: Pristimerin inhibited MGC803 and SGC7901 cell growth, with the IC₅₀ values of 8.5 and 12.6 μmol/L, respectively. Annexin-V/PI staining showed that pristimerin induced the apoptosis of MGC803 and SGC7901 cells in a dose-dependent manner. The cell cycle analysis revealed that pristimerin could induce a G₁-phase arrest. Treatment with pristimerin significantly decreased the mitochondrial membrane potential. Treatment with pristimerin increased the expression of Bax protein and decreased the expression of Bcl-2 in a concentration-dependent manner. Treatment with pristimerin could inhibit tumor growth in the nude mouse model.

CONCLUSION: Pristimerin could inhibit proliferation and induce apoptosis of gastric cancer MGC803 and SGC7901 cells, possibly by inducing the loss of mitochondrial membrane potential.

Risperidone Attenuates Modified Stress-Re-stress Paradigm-Induced Mitochondrial Dysfunction and Apoptosis in Rats Exhibiting Post-traumatic Stress Disorder-Like Symptoms

Mitochondria play a significant role in the pathophysiology of post-traumatic stress disorder (PTSD). Risperidone and paroxetine were evaluated for their effect on mitochondrial dysfunction and mitochondria-dependent apoptosis in discrete brain regions in modified stress re-stress (SRS) animal model of PTSD. Male rats were subjected to stress protocol of 2 h restraint and 20 min forced swim followed by halothane anesthesia on day 2 (D-2). Thereafter, rats were exposed to re-stress (forced swim) on D-8 and at 6-day intervals on D-14, D-20, D-26, and D-32. The rats were treated with risperidone (0.01, 0.1, and 1.0 mg/kg p.o.) and paroxetine (10.0 mg/kg p.o.) from D-8 to D-32. Risperidone at median dose and paroxetine ameliorated modified SRS-induced depressive-like symptom (increase in immobility period) in forced swim, anxiety-like behavior (decrease in percentage of open arm entries and time spent) in elevated plus maze and cognitive deficits (loss in spatial recognition memory) in Y-maze tests on D-32. Risperidone, but not paroxetine, attenuated modified SRS-induced decreases in plasma corticosterone levels. Risperidone ameliorated increase in the activity of mitochondrial respiratory complex (I, II, IV, and V), decreases in the levels of mitochondrial membrane potential, cytochrome-C and caspase-9 in the hippocampus, hypothalamus, pre-frontal cortex, and amygdala. However, both drugs attenuated modified SRS-induced increase in the number of apoptotic cells and caspase-3 levels in all the brain regions indicating anti-apoptotic activity of these drugs. Hence, these results suggest that anti-apoptotic activity could be a common mechanism for anti-PTSD-like effect irrespective of the pathways of apoptosis in the modified SRS model.

Ubiquitin-proteasomal degradation of antiapoptotic survivin facilitates induction of apoptosis in prostate cancer cells by pristimerin

Pristimerin (PM), a quinonemethide triterpenoid, is a promising anticancer agent with potent antiproliferative and apoptosis-inducing activities against cancer cell lines. However, the anticancer activity and mechanisms of PM in prostate cancer cells have not been adequately investigated. Here we report that the degradation of survivin plays an important role in the antiproliferative and proapoptotic effects of PM in carcinoma of the prostate (CaP) cell lines. Treatment with PM inhibited proliferation and induced apoptosis in LNCaP and PC-3 cells as characterized by the loss of cell viability and an increase in Annexin V-binding and cleavage of PARP-1, respectively. The antiproliferative and apoptosis-inducing effects of PM were associated with the inhibition of cell cycle regulatory proteins, antiapoptotic survivin and members of the Bcl-2 family. Data showed that response to PM is regulated by survivin since overexpression of survivin rendered CaP cells resistant to PM. Furthermore, downregulation of survivin by PM was mediated through the ubiquitin-proteasomal degradation. Together, these data demonstrate that pristimerin inhibits proliferation and induces apoptosis in CaP cells by abolishing survivin through the ubiquitin-proteasome pathway.