Sanguinarine overcomes P-glycoprotein-mediated multidrug-resistance via induction of apoptosis and oncosis in CEM-VLB 1000 cells

Unravelling oncosis: morphological and molecular insights into a unique cell death pathway

Programmed cell death (PCD) is a fundamental biological process for maintaining cellular equilibrium and regulating development, health, and disease across all living organisms. Among the various types of PCD, apoptosis plays a pivotal role in numerous diseases, notably cancer. Cancer cells frequently develop mechanisms to evade apoptosis, increasing resistance to standard chemotherapy treatments. This resistance has prompted extensive research into alternative mechanisms of programmed cell death. One such pathway is oncosis, characterized by significant energy consumption, cell swelling, dilation of the endoplasmic reticulum, mitochondrial swelling, and nuclear chromatin aggregation. Recent research suggests that oncosis can impact conditions such as chemotherapeutic cardiotoxicity, myocardial ischemic injury, stroke, and cancer, mediated by specific oncosis-related proteins. In this review, we provide a detailed examination of the morphological and molecular features of oncosis and discuss various natural or small molecule compounds that can induce this type of cell death. Additionally, we summarize the current understanding of the molecular mechanisms underlying oncosis and its role in both normal physiology and pathological conditions. These insights aim to illuminate future research directions and propose innovative strategies for leveraging oncosis as a therapeutic tool against human diseases and cancer resistance.

Sanguinarine mediated apoptosis in Non-Small Cell Lung Cancer via generation of reactive oxygen species and suppression of JAK/STAT pathway

Effective treatment of lung cancer remains a significant clinical challenge due to its multidrug resistance and side effects of the current treatment options. The high mortality associated with this malignancy indicates the need for new therapeutic interventions with fewer side effects. Natural compounds offer various benefits such as easy access, minimal side effects, and multi-molecular targets and thus, can prove useful in treating lung cancer. Sanguinarine (SNG), a natural compound, possesses favorable therapeutic potential against a variety of cancers. Here, we examined the underlying molecular mechanisms of SNG in Non-Small Cell Lung Cancer (NSCLC) cells. SNG suppressed cell growth and induced apoptosis via downregulation of the constitutively active JAK/STAT pathway in all the NSCLC cell lines. siRNA silencing of STAT3 in NSCLC cells further confirmed the involvement of the JAK/STAT signaling cascade. SNG treatment increased Bax/Bcl-2 ratio, which contributed to a leaky mitochondrial membrane leading to cytochrome c release accompanied by caspase activation. In addition, we established the antitumor effects of SNG through reactive oxygen species (ROS) production, as inhibiting ROS production prevented the apoptosis-inducing potential of SNG. In vivo xenograft tumor model further validated our in vitro findings. Overall, our study investigated the molecular mechanisms by which SNG induces apoptosis in NSCLC, providing avenues for developing novel natural compound-based cancer therapies.

Jaridon 6, a new diterpene from Rabdosia rubescens (Hemsl.) Hara, can display anti-gastric cancer resistance by inhibiting SIRT1 and inducing autophagy

Tumor resistance is the main cause of treatment failure and is associated with many tumor factors. Jaridon 6, a new diterpene extracted from Rabdosia rubescens (Hemsl.) Hara, which has been previously extracted by our research team, has been tested having more obvious advantages in resistant tumor cells. However, its mechanism is unclear. In this study, we studied the effect and the specific mechanism of Jaridon 6 in resistant gastric cancer cells. Cytotoxicity test, colony test, western blotting, and nude test verified the anti-drug resistance ability of Jaridon 6 in the MGC803/PTX and MGC803/5-Fu cells. Jaridon 6 has shown obvious inhibitory effects in the sirtuin 1 (SIRT1) enzyme test. Transmission electron microscopy and immunofluorescence tests further proved the autophagic action of Jaridon 6. Jaridon 6 could inhibit the proliferation of the resistant gastric cancer cell in vivo and in vitro. Jaridon 6 inhibited SIRT1 enzyme and induced autophagy by inhibiting the phosphoinositide 3-kinase/protein kinase B (PI3K/AKT) pathway. Thus, it may be considered for treating gastric cancer resistance by individual or combined administration, as an SIRT1 inhibitor and autophagy inducer.

Epidemic dropsy toxin, sanguinarine chloride, stimulates sucrose-sensitive hemolysis and breakdown of membrane phospholipid asymmetry in human erythrocytes

Sanguinarine (SGN) is a benzophenathridine alkaloid extracted from Sanguinaria canadensis plant. SGN is incriminated in epidemic dropsy (ED) characterized by multiple-organ failure and anemia. Nevertheless, how SGN leads to anemia of ED remains poorly understood. This study was thus initiated to investigate the interaction of SGN with human red blood cells (RBCs) and to delineate associated molecular mechanisms. Heparin- and EDTA-anticoagulated blood was collected from healthy participants and whole blood was analyzed for a complete blood count, while isolated RBCs were examined for hemolytic and eryptotic markers following exposure to 1-100 μM SGN for 24 h at 37 °C. Calcium was measured by Fluo4/AM, hemolysis by hemoglobin leakage, membrane scrambling by Annexin V-FITC, cell size by forward scatter (FSC), cell granularity by side scatter (SSC), and oxidative stress by H₂DCFDA. SGN led to increased Fluo4 fluorescence and dose-dependent hemolysis which was not ameliorated by exclusion of extracellular Ca²⁺ but was nevertheless sensitive to hyperosmotic conditions and to the presence of aspirin. SGN also caused significant increase in Annexin V-positive cells, decreased FSC and SSC values, and elevated DCF fluorescence. Moreover, significantly reduced lymphocyte and basophil percentages along with selective toxicity to platelets was noted. Collectively, SGN possesses sucrose- and cyclooxygenase-sensitive hemolytic potential and elicits eryptosis characterized by Ca²⁺ accumulation, phosphatidylserine externalization, morphological alterations including cell shrinkage and loss of granularity, and oxidative stress. In conclusion, this report reveals a novel activity of SGN against human RBCs and informs prospective policies in ED prevention and management.

Significance and Mechanisms of P-glycoprotein in Central Nervous System Diseases

P-glycoprotein (P-gp) is a member of ATP-Binding Cassette (ABC) transporter family. Because of its characteristic luminal surface location, high transport potency and structural specificity, Pgp is regarded as a selective gatekeeper of the Blood Brain Barrier (BBB) to prevent the entry of toxins or unwanted substances into the brain. In recent years, increasing evidence has shown that P-gp is involved in the immune inflammatory response in the Central Nervous System (CNS) disorders by regulating microglia activation, and mediating immune cell migration. Furthermore, Glucocorticoid Receptor (GR) may play a crucial role in P-gp-mediated microglia activation and immune cell migration via GR-mediated mRNA decay. In this article, we will review P-gp structure, distribution, function, regulatory mechanisms, inhibitors and effects of P-gp in the pathogenesis of several CNS diseases and will discuss the role of P-gp in microglia activation, immune cell migration and the relationship with cytokine secretion.

Induction of programmed necrosis: A novel anti-cancer strategy for natural compounds

Cell death plays a critical role in organism development and the pathogenesis of diseases. Necrosis is considered a non-programmed cell death in an extreme environment. Recent advances have provided solid evidence that necrosis could be programmed and quite a few types of programmed necrosis, such as necroptosis, ferroptosis, pyroptosis, paraptosis, mitochondrial permeability transition-driven necrosis, and oncosis, have been identified. The specific biomarkers, detailed signaling, and precise pathophysiological importance of programmed necrosis are yet to be clarified, but these forms of necrosis provide novel strategies for the treatment of various diseases, including cancer. Natural compounds are a unique source of lead compounds for the discovery of anti-cancer drugs. Natural compounds can induce both apoptosis and programmed necrosis. In this review, we summarized the recent progress of programmed necrosis and introduced their natural inducers. Noptosis, which is a novel type of programmed necrosis that is strictly dependent on NAD(P)H: quinone oxidoreductase 1-derived oxidative stress was proposed. Furthermore, the anti-cancer strategies that take advantage of programmed necrosis and the main concerns from the scientific community in this regard were discussed.

The Biological Activity of Natural Alkaloids against Herbivores, Cancerous Cells and Pathogens

The growing incidence of microorganisms that resist antimicrobials is a constant concern for the scientific community, while the development of new antimicrobials from new chemical entities has become more and more expensive, time-consuming, and exacerbated by emerging drug-resistant strains. In this regard, many scientists are conducting research on plants aiming to discover possible antimicrobial compounds. The secondary metabolites contained in plants are a source of chemical entities having pharmacological activities and intended to be used for the treatment of different diseases. These chemical entities have the potential to be used as an effective antioxidant, antimutagenic, anticarcinogenic and antimicrobial agents. Among these pharmacologically active entities are the alkaloids which are classified into a number of classes, including pyrrolizidines, pyrrolidines, quinolizidines, indoles, tropanes, piperidines, purines, imidazoles, and isoquinolines. Alkaloids that have antioxidant properties are capable of preventing a variety of degenerative diseases through capturing free radicals, or through binding to catalysts involved indifferent oxidation processes occurring within the human body. Furthermore, these entities are capable of inhibiting the activity of bacteria, fungi, protozoan and etc. The unique properties of these secondary metabolites are the main reason for their utilization by the pharmaceutical companies for the treatment of different diseases. Generally, these alkaloids are extracted from plants, animals and fungi. Penicillin is the most famous natural drug discovery deriving from fungus. Similarly, marines have been used as a source for thousands of bioactive marine natural products. In this review, we cover the medical use of natural alkaloids isolated from a variety of plants and utilized by humans as antibacterial, antiviral, antifungal and anticancer agents. An example for such alkaloids is berberine, an isoquinoline alkaloid, found in roots and stem-bark of Berberis asculin P. Renault plant and used to kill a variety of microorganisms.

Sanguinarine Induces Apoptosis Pathway in Multiple Myeloma Cell Lines via Inhibition of the JaK2/STAT3 Signaling

Sanguinarine (SNG), a benzophenanthridine alkaloid, has displayed various anticancer abilities in several vivo and in vitro studies. However, the anticancer potential of SNG is yet to be established in multiple myeloma (MM), a mostly incurable malignancy of plasma cells. In this study, we aimed to investigate the potential anti-proliferative and pro-apoptotic activities of SNG in a panel of MM cell lines (U266, IM9, MM1S, and RPMI-8226). SNG treatment of MM cells resulted in a dose-dependent decrease in cell viability through mitochondrial membrane potential loss and activation of caspase 3, 9, and cleavage of PARP. Pre-treatment of MM cells with a universal caspase inhibitor, Z-VAD-FMK, prevented SNG mediated loss of cell viability, apoptosis, and caspase activation, confirming that SNG-mediated apoptosis is caspase-dependent. The SNG-mediated apoptosis appears to be resulted from suppression of the constitutively active STAT3 with a concomitant increase in expression of protein tyrosine phosphatase (SHP-1). SNG treatment of MM cells leads to down-regulation of the anti-apoptotic proteins including cyclin D, Bcl-2, Bclxl, and XIAP. In addition, it also upregulates pro-apoptotic protein, Bax. SNG mediated cellular DNA damage in MM cell lines by induction of oxidative stress through the generation of reactive oxygen species and depletion of glutathione. Finally, the subtoxic concentration of SNG enhanced the cytotoxic effects of anticancer drugs bortezomib (BTZ) by suppressing the viability of MM cells via induction of caspase-mediated apoptosis. Altogether our findings demonstrate that SNG induces mitochondrial and caspase-dependent apoptosis, generates oxidative stress, and suppresses MM cell lines proliferation. In addition, co-treatment of MM cell lines with sub-toxic doses of SNG and BTZ potentiated the cytotoxic activity. These results would suggest that SNG could be developed into therapeutic agent either alone or in combination with other anticancer drugs in MM.

Downregulation of miR-222-3p Reverses Doxorubicin-Resistance in LoVo Cells Through Upregulating Forkhead Box Protein P2 (FOXP2) Protein

BACKGROUND Doxorubicin (DOX) is a potent chemotherapeutic agent used to treat colon cancer. Despite impressive initial clinical responses, drug resistance has dramatically compromised the effectiveness of DOX. However, the underlying mechanisms of chemotherapeutic resistance in colon cancer remain poorly understood. MATERIAL AND METHODS In this study, we compared the expression of miR-222-3p in DOX-resistant colon cancer cells (LoVo/ADR) with the corresponding DOX-sensitive parental cells (LoVo/S) using quantitative real-time PCR. In addition, miR-222-3p inhibitors were infected into LoVo/ADR cell lines and the effects of this treatment were assessed. The Cell Counting Kit 8 assay was employed to verify the sensitivity of colon cancer cell lines to DOX. EdU (5-ethynyl-2'-deoxyuridine) assay, flow cytometry, and in vivo subcutaneous tumorigenesis were used to assess cell proliferation and apoptosis. Transwell and wound healing assays were used to investigate cell migration after adding DOX. Additionally, the expression of forkhead box protein P2 (FOXP2), P-glycoprotein (P-gp) and caspase pathway-associated markers was assessed by western blotting. RESULTS Our results showed that miR-222-3p was upregulated in LoVo/ADR compared with the expression in LoVo/S cells. Additionally, downregulation of miR-222-3p in LoVo/ADR cells increased their sensitivity to DOX, reduced P-gp expression, and activated the caspase pathway. However, the downregulation of FOXP2 could efficiently reverse the effect of miR-222-3p inhibitors on LoVo/ADR cells. CONCLUSIONS Taken together, our results showed that miR-222-3p induced DOX resistance via suppressing FOXP2, upregulating P-gp, and inhibiting the caspase pathway.

Knockdown of long non‑coding RNA PVT1 reverses multidrug resistance in colorectal cancer cells

Multidrug resistance (MDR) is one of the primary causes of chemotherapy failure in colorectal cancer (CRC), and extensive biological studies into MDR are required. The non-coding RNA plasmacytoma variant translocation 1 (PVT1) has been demonstrated to be associated with low survival rates in patients with CRC. However, whether PVT1 serves a critical function in the MDR of CRC remains to be determined. To determine the association between PVT1 expression and 5-fluorouracil (5-FU) resistance in CRC, the expression levels of PVT1 mRNA in 5-FU-resistant CRC tissues and cell lines (HCT-8/5-FU and HCT-116/5-FU) were assessed by a reverse transcription-quantitative polymerase chain reaction (RT-qPCR). Cytotoxicity was evaluated using a Cell Counting Kit-8 assay and apoptosis rates were assessed via flow cytometry. In the present study, PVT1 mRNA was highly expressed in 5-FU-resistant CRC tissues and cell lines. HCT-8/5-FU and HCT-116/5-FU cells transfected with small interfering RNA PVT1 and treated with 5-FU exhibited higher apoptotic rates and lower survival rates. By contrast, overexpression of PVT1 in HCT-8 and HCT-116 cells transfected with lentiviral vector-PVT1-green fluorescent protein and treated with 5-FU exhibited lower apoptosis rates and higher survival rates. RT-qPCR and western blotting demonstrated that the overexpression of PVT1 increased the mRNA and protein expression levels of multidrug resistance-associated protein 1, P-glycoprotein, serine/threonine-protein kinase mTOR and apoptosis regulator Bcl2. The present study indicates that PVT1 overexpression may promote MDR in CRC cells, and suggested that inhibition of PVT1 expression may be an effective therapeutic strategy for reversing MDR in CRC.

Molecular targets and anticancer potential of sanguinarine-a benzophenanthridine alkaloid

BACKGROUND

Cancer is an enormous global health burden, and should be effectively addressed with better therapeutic strategies. Currently, over 60% of the clinically approved anticancer agents are either directly isolated from natural sources or are modified from natural lead molecules. Sanguinarine (SNG), a quaternary benzophenanthridine alkaloid has gained increasing attention in recent years as a potential anticancer agent.

PURPOSE

There is a large untapped source of phytochemical-based anticancer agents remaining to be explored. This review article aims to recapitulate different anticancer properties of SNG, and describes some of the molecular targets involved in exerting its effect. It also depicts the pharmacokinetic and toxicological properties of SNG, two parameters important in determining the druggability of a molecule.

METHODS

Numerous in vivo and in vitro published studies have signified the anticancer properties of SNG. In order to collate and decipher these properties, an extensive literature search was conducted in PubMed, ScienceDirect, and Scopus using keywords followed by the evaluation of the relevant articles where the relevant reports are integrated and analyzed.

RESULTS

Apart from inducing cell death, SNG inhibits pro-tumorigenic processes such as invasion, angiogenesis, and metastasis in different cancers. Moreover, SNG has been shown to synergistically enhance the sensitivity of several chemotherapeutic agents and is effective against a variety of multi-drug resistant cancers.

Natural alkaloids as P-gp inhibitors for multidrug resistance reversal in cancer

The biggest challenge associated with cancer chemotherapy is the development of cross multi-drug resistance to almost all anti-cancer agents upon chronic treatment. The major contributing factor for this resistance is efflux of the drugs by the p-glycoprotein pump. Over the years, inhibitors of this pump have been discovered to administer them in combination with chemotherapeutic agents. The clinical failure of first and second generation P-gp inhibitors (such as verapamil and cyclosporine analogs) has led to the discovery of third generation potent P-gp inhibitors (tariquidar, zosuquidar, laniquidar). Most of these inhibitors are nitrogenous compounds and recently a natural alkaloid CBT-01^® (tetrandrine) has advanced to the clinical phase. CBT-01 demonstrated positive results in Phase-I study in combination with paclitaxel, which warranted conducting it's Phase II/III trial. Apart from this, there exist a large number of natural alkaloids possessing potent inhibition of P-gp efflux pump and other related pumps responsible for the development of resistance. Despite the extensive contribution of alkaloids in this area, has never been reviewed. The present review provides a comprehensive account on natural alkaloids possessing P-gp inhibition activity and their potential for multidrug resistance reversal in cancer.

Anticancer potential of sanguinarine for various human malignancies

Sanguinarine (Sang) - a benzophenanthridine alkaloid extracted from Sanguinaria canadensis - exhibits antioxidant, anti-inflammatory, proapoptotic and growth inhibitory activities on tumor cells of various cancer types as established by in vivo and in vitro studies. Although the underlying mechanism of Sang antitumor activity is yet to be fully elucidated, Sang has displayed multiple biological effects, which remain to suggest its possible use in plant-derived treatments of human malignancies. This review covers the anticancer abilities of Sang including inhibition of aberrantly activated signal transduction pathways, induction of cell death and inhibition of cancer cell proliferation. It also highlights Sang-mediated inhibition of angiogenesis, inducing the expression of tumor suppressors, sensitization of cancer cells to standard chemotherapeutics to enhance their cytotoxic effects, while addressing the present need for further pharmacokinetic-based studies.

Natural Products as Alternative Choices for P-Glycoprotein (P-gp) Inhibition

Multidrug resistance (MDR) is regarded as one of the bottlenecks of successful clinical treatment for numerous chemotherapeutic agents. Multiple key regulators are alleged to be responsible for MDR and making the treatment regimens ineffective. In this review, we discuss MDR in relation to P-glycoprotein (P-gp) and its down-regulation by natural bioactive molecules. P-gp, a unique ATP-dependent membrane transport protein, is one of those key regulators which are present in the lining of the colon, endothelial cells of the blood brain barrier (BBB), bile duct, adrenal gland, kidney tubules, small intestine, pancreatic ducts and in many other tissues like heart, lungs, spleen, skeletal muscles, etc. Due to its diverse tissue distribution, P-gp is a novel protective barrier to stop the intake of xenobiotics into the human body. Over-expression of P-gp leads to decreased intracellular accretion of many chemotherapeutic agents thus assisting in the development of MDR. Eventually, the effectiveness of these drugs is decreased. P-gp inhibitors act by altering intracellular ATP levels which are the source of energy and/or by affecting membrane contours to increase permeability. However, the use of synthetic inhibitors is known to cause serious toxicities. For this reason, the search for more potent and less toxic P-gp inhibitors of natural origin is underway. The present review aims to recapitulate the research findings on bioactive constituents of natural origin with P-gp inhibition characteristics. Natural bioactive constituents with P-gp modulating effects offer great potential for semi-synthetic modification to produce new scaffolds which could serve as valuable investigative tools to recognize the function of complex ABC transporters apart from evading the systemic toxicities shown by synthetic counterparts. Despite the many published scientific findings encompassing P-gp inhibitors, however, this article stand alones because it provides a vivid picture to the readers pertaining to Pgp inhibitors obtained from natural sources coupled with their mode of action and structures. It provides first-hand information to the scientists working in the field of drug discovery to further synthesise and discover new P-gp inhibitors with less toxicity and more efficacies.

MiR-129 regulates cisplatin-resistance in human gastric cancer cells by targeting P-gp

Development of multiple drug resistance (MDR) to chemotherapy is the major reason for the failure of gastric cancer (GC) treatment. P-glycoprotein (P-gp), which is encoded by MDR gene 1, as one of the mechanisms responsible for MDR. Mounting evidence has demonstrated that the drug-induced dysregulation of microRNAs (miRNAs) function may mediate MDR in cancer cells. However, the underling mechanisms of miRNA-mediated MDR in GC remain unclear. Here, we found that miR-129 was downregulated in cisplatin-resistant GC tissues/cells. Our results also showed that overexpression of miR-129 decreased cisplatin-resistance in cisplatin-resistant GC cells, and miR-129 knockdown reduced chemosensitivity to cisplatin in cisplatin-sensitive GC cells. Furthermore, miR-129 activated the intrinsic apoptotic pathway via upregulating caspase-9 and caspase-3. Most importantly, we further confirmed that P-gp is the functional target of miR-129 by regulating cisplatin-resistance in GC cells. These results suggested that miR-129 reversed cisplatin-resistance through inhibiting the P-gp expression in GC cells.

Overexpression of long non-coding RNA PVT1 in gastric cancer cells promotes the development of multidrug resistance

BACKGROUND

The development of multidrug resistance (MDR) is a crucial problem of therapy failure in gastric cancer, which results in disease recurrence and metastasis. Plasmacytoma variant translocation 1 (PVT-1), a long non-coding RNA (lncRNA), was previously found to be increased in gastric cancer patients and regulated the chemotherapy sensitivity in pancreatic cancer cells. However, the role of PVT1 in multidrug resistant Gastric cancer remains largely unexplored.

METHODS

In this study, the mRNA levels of PVT1 in gastric cancer tissues of cisplatin-resistant patients and two kinds of cisplatin-resistant cells BGC823/DDP and SGC7901/DDP were detected by qRT-PCR. The influence of PVT1 knockdown or overexpression on anticancer drug resistance was assessed by measuring the cytotoxicity of cisplatin and the rate of apoptosis detected by CCK-8 assay and flow cytometry, respectively. Further, we investigated the expression levels of MDR1, MRP, mTOR and HIF-1α by qRT-PCR and western blotting.

RESULTS

PVT-1 was highly expressed in gastric cancer tissues of cisplatin-resistant patients and cisplatin-resistant cells. In addition, BGC823/DDP and SGC7901/DDP cells transfected with PVT-1 siRNA and treated with cisplatin exhibited significant lower survival rate and high percentage of apoptotic tumor cells. While, PVT1 overexpression exhibit the anti-apoptotic property in BGC823 and SGC7901 cells transfected with LV-PVT1-GFP and treated with cisplatin. Moreover, qRT-PCR and western blotting revealed that PVT1 up-regulation increased the expression of MDR1, MRP, mTOR and HIF-1α.

CONCLUSIONS

Overexpression of LncRNA PVT1 in gastric carcinoma promotes the development of MDR, suggesting an efficacious target for reversing MDR in gastric cancer therapy.

Chelerythrine inhibits the sarco/endoplasmic reticulum Ca(2+)-ATPase and results in cell Ca(2+) imbalance

The isoquinoline alkaloid chelerythrine is described as an inhibitor of SERCA. The ATPase inhibition presented two non-competitive components, Ki1=1, 2 μM and Ki2=26 μM. Conversely, chelerythrine presented a dual effect on the p-nitrophenylphosphatase (pNPPase) of SERCA. Ca(2+)-dependent pNPPase was activated up to ∼5 μM chelerythrine with inhibition thereafter. Ca(2+)-independent pNPPase was solely inhibited. The phosphorylation of SERCA with ATP reached half-inhibition with 10 μM chelerythrine and did not parallel the decrease of ATPase activity. In contrast, chelerythrine up to 50 μM increased the phosphorylation by Pi. Cross-linking of SERCA with glutaraldehyde was counteracted by high concentrations of chelerythrine. The controlled tryptic digestion of SERCA shows that the low-affinity binding of chelerythrine evoked an E2-like pattern. Our data indicate a non-competitive inhibition of ATP hydrolysis that favors buildup of the E2-conformers of the enzyme. Chelerythrine as low as 0.5-1.5 μM resulted in an increase of intracellular Ca(2+) on cultured PBMC cells. The inhibition of SERCA and the loss of cell Ca(2+) homeostasis could in part be responsible for some described cytotoxic effects of the alkaloid. Thus, the choice of chelerythrine as a PKC-inhibitor should consider its potential cytotoxicity due to the alkaloid's effects on SERCA.

Multiple mechanisms of cell death induced by chelidonine in MCF-7 breast cancer cell line

In a preliminary study screening anti-proliferative natural alkaloids, a very potent benzophenanthridine, chelidonine showed strong cytotoxicity in cancer cells. While several modes of death have been identified, most of anti-cancer attempts have focused on stimulation of cells to undergo apoptosis. Chelidonine seems to trigger multiple mechanisms in MCF-7 breast cancer cells. It induces both apoptosis and autophagy modes of cell death in a dose dependent manner. Alteration of expression levels of bax/bcl2, and dapk1a by increasing concentration of chelidonine approves switching the death mode from apoptosis induced by very low to autophagy by high concentrations of this compound. On the other hand, submicromolar concentrations of chelidonine strongly suppressed telomerase at both enzyme activity and hTERT transcriptional level. Long exposure of the cells to 50 nanomolar concentration of chelidonine considerably accelerated senescence. Altogether, chelidonine may provide a promising chemistry from nature to treat cancer.

Alkaloids from Toddalia asiatica and their cytotoxic, antimicrobial and antifungal activities

Phytochemical investigation of the ethanol extract from the roots of Toddalia asiatica resulted in the isolation of eight new alkaloids, 8-methoxynorchelerythrine (1), 11-demethylrhoifoline B (2), 8-methoxynitidine (3), 8-acetylnorchelerythrine (4), 8,9,10,12-tetramethoxynorchelerythrine (5), isointegriamide (6), 1-demethyl dicentrinone (7), and 11-hydroxy-10-methoxy-(2,3)-methylenedioxytetrahydroprotoberberine (8), together with 10 known alkaloids. Their structures were determined on the basis of spectroscopic analyses, including 1D-NMR, 2D-NMR, and HR-ESI-MS. The isolated components were evaluated in vitro for cytotoxic activities against eight tumor cell lines, antimicrobial activities against two Gram-positive bacteria and five Gram-negative bacteria, and antifungal activities against five pathogens. Benzo[c]phenanthridine and secobenzo[c]phenantridine alkaloids exhibited significant cytotoxic, antimicrobial and antifungal properties.

Oncosis: an important non-apoptotic mode of cell death

It is now increasingly accepted that apoptosis may not be the only form of cell death seen in vitro and in vivo; hence there is a need to study novel forms of cell death. The explosion of cell death research that followed the recognition of apoptosis by Kerr and colleagues in the late 1960s completely obscured the fact that apoptosis is not the only form of cell death. Apoptosis manifests itself by cell shrinkage followed by breakup; another form (oncosis) is almost the opposite: it involves cell swelling and coagulation of the cytoplasm. The name oncosis was chosen over a century ago by von Recklinghausen, a top collaborator of Rudolph Virchow and thereby one of the founders of cellular pathology. Nevertheless, oncosis was forgotten, largely because a satisfactory technique for preparing tissue sections did not exist at the time. Also confusion developed regarding the distinction between oncosis as a mode of cell injury and cell death, and necrosis as a degradation process following cell death. In this review we have described the many characteristics of oncosis from a morphological and biochemical standpoint, and we briefly examine the application of oncosis in disease processes.

Alkaloids isolated from natural herbs as the anticancer agents

Alkaloids are important chemical compounds that serve as a rich reservoir for drug discovery. Several alkaloids isolated from natural herbs exhibit antiproliferation and antimetastasis effects on various types of cancers both in vitro and in vivo. Alkaloids, such as camptothecin and vinblastine, have already been successfully developed into anticancer drugs. This paper focuses on the naturally derived alkaloids with prospective anticancer properties, such as berberine, evodiamine, matrine, piperine, sanguinarine, and tetrandrine, and summarizes the mechanisms of action of these compounds. Based on the information in the literature that is summarized in this paper, the use of alkaloids as anticancer agents is very promising, but more research and clinical trials are necessary before final recommendations on specific alkaloids can be made.

A model for cardiomyocyte cell death: insights into mechanisms of oncosis

It is now known that there are at least two basic patterns of cell injury progressing to cell death: cell injury with swelling, known as oncosis, and cell injury with shrinkage, known as apoptosis. Both types of cell death are "programmed" in the sense that the genetic information and many of the enzymes and other factors pre-exist in the cell. Previous investigation has pointed to cardiomyocyte ischemic injury evolving as the oncotic pattern of injury, although apoptosis has also been implicated. This study was designed, using a unique cell model system, to gain insight into the molecular events of anticancer agent-induced cardiomyocyte injury. Cardiomyocytes exposed for 2 h to 1.5 μg/ml sanguinarine consistently displayed the morphology of apoptosis in over 80% of cells, whereas a higher dose of 25 μg/ml at 2 h yielded the pattern of oncosis in over 90% of cells. Microarray analysis revealed altered expression of 2514 probes in sanguinarine-induced oncosis and 1643 probes in apoptosis at a level of significance of p<0.001. Some of the inductions such as perforin were found to be higher than 11-fold in oncosis. When perforin was blocked by perforin-specific siRNA we found a reduction in oncotic cell death. These results strengthen the notion that oncosis is not representative of nonspecific necrosis, but constitutes a genetically controlled form of "programmed cell death"; and also that oncosis might represent a pathogenetic mechanism of cardiomyocyte injury. This is also the first demonstration of the involvement of perforin in cardiomyocyte oncosis.

Secondary Metabolites from Plants Inhibiting ABC Transporters and Reversing Resistance of Cancer Cells and Microbes to Cytotoxic and Antimicrobial Agents

Fungal, bacterial, and cancer cells can develop resistance against antifungal, antibacterial, or anticancer agents. Mechanisms of resistance are complex and often multifactorial. Mechanisms include: (1) Activation of ATP-binding cassette (ABC) transporters, such as P-gp, which pump out lipophilic compounds that have entered a cell, (2) Activation of cytochrome p450 oxidases which can oxidize lipophilic agents to make them more hydrophilic and accessible for conjugation reaction with glucuronic acid, sulfate, or amino acids, and (3) Activation of glutathione transferase, which can conjugate xenobiotics. This review summarizes the evidence that secondary metabolites (SM) of plants, such as alkaloids, phenolics, and terpenoids can interfere with ABC transporters in cancer cells, parasites, bacteria, and fungi. Among the active natural products several lipophilic terpenoids [monoterpenes, diterpenes, triterpenes (including saponins), steroids (including cardiac glycosides), and tetraterpenes] but also some alkaloids (isoquinoline, protoberberine, quinoline, indole, monoterpene indole, and steroidal alkaloids) function probably as competitive inhibitors of P-gp, multiple resistance-associated protein 1, and Breast cancer resistance protein in cancer cells, or efflux pumps in bacteria (NorA) and fungi. More polar phenolics (phenolic acids, flavonoids, catechins, chalcones, xanthones, stilbenes, anthocyanins, tannins, anthraquinones, and naphthoquinones) directly inhibit proteins forming several hydrogen and ionic bonds and thus disturbing the 3D structure of the transporters. The natural products may be interesting in medicine or agriculture as they can enhance the activity of active chemotherapeutics or pesticides or even reverse multidrug resistance, at least partially, of adapted and resistant cells. If these SM are applied in combination with a cytotoxic or antimicrobial agent, they may reverse resistance in a synergistic fashion.

Hydrocinchonine, cinchonine, and quinidine potentiate paclitaxel-induced cytotoxicity and apoptosis via multidrug resistance reversal in MES-SA/DX5 uterine sarcoma cells

Multidrug resistance (MDR) is one of important issues to cause the chemotherapy failure against cancers including gynecological malignancies. Despite some MDR reversal evidences of natural compounds including quinidine and cinchonine, there are no reports on MDR reversal activity of hydrocinchonine with its analogues quinidine and cinchonine especially in uterine sarcoma cells. Thus, in the current study, we comparatively investigated the potent efficacy of hydrocinchonine and its analogues quinidine and cinchonine as MDR-reversal agents for combined therapy with antitumor agent paclitaxel (TAX). Hydrocinchonine, cinchonine, and quinidine significantly increased the cytotoxicity of TAX in P-glycoprotein (gp)-positive MES-SA/DX5, but not in the P-gp-negative MES-SA cells at nontoxic concentrations by 3-(4,5-dimethylthiazol-2-yl)-2,5--diphenyltetrazolium bromide (MTT) assay. Rhodamine assay also revealed that hydrocinchonine, cinchonine, and quinidine effectively enhanced the accumulation of a P-gp substrate, rhodamine in TAX-treated MES-SA/DX5 cells compared with TAX-treated control. In addition, hydrocinchonine, cinchonine, and quinidine effectively cleaved poly (ADP-ribose) polymerase (PARP), activated caspase-3, and downregulated P-gp expression as well as increased sub-G1 apoptotic portion in TAX-treated MES-SA/DX5 cells. Taken together, hydrocinchonine exerted MDR reversal activity and synergistic apoptotic effect with TAX in MES-SA/DX5 cells almost comparable with quinidine and cinchonine as a potent MDR-reversal and combined therapy agent with TAX.

Sanguinarine

Sanguinarine is an alkaloid found in many medicinal plants. It has diverse biological activities, including modulation of nuclear factor-kappaB and of several enzymes. It is also known to induce apoptosis, perturb microtubules, and to have antimicrobial effects. This article reviews its cardiovascular properties, including hypotensive, antiplatelet, and positive inotropic effects. Its pharmacokinetics, and toxicology, including its carcinogenic potential, are also discussed. Further pharmacological and toxicological studies with sanguinarine are needed before its therapeutic use can be considered.

Aurintricarboxylic acid inhibits protein synthesis independent, sanguinarine-induced apoptosis and oncosis

Sanguinarine, a benzophenanthridine alkaloid, has anticancer potential through induction of cell death. We previously demonstrated that sanguinarine treatment at a low concentration (1.5 microg/ml) induced apoptosis in K562 human erythroleukemia cells, and a high concentration (12.5 microg/ml) induced the morphology of blister formation or oncosis-blister cell death (BCD). Treatment of cells at an intermediate sanguinarine concentration (6.25 microg/ml) induced diffuse swelling or oncosis-diffuse cell swelling (DCS). To assess the underlying mechanism of sanguinarine-induced apoptosis and oncosis-BCD in K562 cells, we studied their response to pre-treatment with two chemical compounds: aurintricarboxylic acid (ATA) and cycloheximide (CHX). The pretreatment effects of both chemical compounds on apoptosis and oncosis-BCD were evaluated by measuring multiple parameters using quantitative morphology, electron microscopy, terminal deoxynucleotidyl transferase (TdT) end-labeling and annexin-V-binding. ATA, a DNA endonuclease inhibitor, efficiently prevented DNA nicking and inhibited apoptosis almost completely and oncosis-BCD by about 40%, while CHX, a protein synthesis inhibitor, failed to inhibit both apoptosis and oncosis-BCD. These results demonstrate, first, the importance of endonuclease in sanguinarine-induced apoptosis and to some extent in oncosis-BCD and, second, that this inhibition does not require de novo protein synthesis.