A novel form of melanoma apoptosis resistance: melanogenesis up-regulation in apoptotic B16-F0 cells delays ursolic acid-triggered cell death

Ursolic Acid's Alluring Journey: One Triterpenoid vs. Cancer Hallmarks

Cancer is a multifactorial disease characterized by various hallmarks, including uncontrolled cell growth, evasion of apoptosis, sustained angiogenesis, tissue invasion, and metastasis, among others. Traditional cancer therapies often target specific hallmarks, leading to limited efficacy and the development of resistance. Thus, there is a growing need for alternative strategies that can address multiple hallmarks concomitantly. Ursolic acid (UA), a naturally occurring pentacyclic triterpenoid, has recently emerged as a promising candidate for multitargeted cancer therapy. This review aims to summarize the current knowledge on the anticancer properties of UA, focusing on its ability to modulate various cancer hallmarks. The literature reveals that UA exhibits potent anticancer effects through diverse mechanisms, including the inhibition of cell proliferation, induction of apoptosis, suppression of angiogenesis, inhibition of metastasis, and modulation of the tumor microenvironment. Additionally, UA has demonstrated promising activity against different cancer types (e.g., breast, lung, prostate, colon, and liver) by targeting various cancer hallmarks. This review discusses the molecular targets and signaling pathways involved in the anticancer effects of UA. Notably, UA has been found to modulate key signaling pathways, such as PI3K/Akt, MAPK/ERK, NF-κB, and Wnt/β-catenin, which play crucial roles in cancer development and progression. Moreover, the ability of UA to destroy cancer cells through various mechanisms (e.g., apoptosis, autophagy, inhibiting cell growth, dysregulating cancer cell metabolism, etc.) contributes to its multitargeted effects on cancer hallmarks. Despite promising anticancer effects, this review acknowledges hurdles related to UA's low bioavailability, emphasizing the need for enhanced therapeutic strategies.

Melanization as unfavorable factor in amelanotic melanoma cell biology

The biology of three amelanotic melanoma cell lines (Ab, B16F10, and A375) of different species origin was analyzed during in vitro induced melanization in these cells. Melanin production was induced by DMEM medium characterized by a high level of L-tyrosine (a basic amino acid for melanogenesis). The biodiversity of amelanotic melanoma cells was confirmed by their different responses to melanogenesis induction; Ab hamster melanomas underwent intensive melanization, mouse B16F10 darkened slightly, while human A375 cells did not show any change in melanin content. Highly melanized Ab cells entered a cell death pathway, while slight melanization did not influence cell biology in a significant way. The rapid and high melanization of Ab cells induced apoptosis documented by phosphatidylserine externalization, caspase activation, and mitochondrial energetic state decrease. Melanoma cell type, culture medium, and time of incubation should be taken into consideration during amelanotic melanoma cell culture in vitro. L-tyrosine, as a concentration-dependent factor presented in the culture media, could stimulate some amelanotic melanoma cell lines (Ab, B16F10) to melanin production. The presence of melanin should be considered in the examination of antimelanoma compounds in vitro, because induction of melanin may interfere or be helpful in the treatment of amelanotic melanoma.

Involvement of autophagy in diosgenin‑induced megakaryocyte differentiation in human erythroleukemia cells

Natural agents have been used to restart the process of differentiation that is inhibited during leukemic transformation of hematopoietic stem or progenitor cells. Autophagy is a housekeeping pathway that maintains cell homeostasis against stress by recycling macromolecules and organelles and plays an important role in cell differentiation. In the present study, an experimental model was established to investigate the involvement of autophagy in the megakaryocyte differentiation of human erythroleukemia (HEL) cells induced by diosgenin [also known as (25R)‑Spirosten‑5‑en‑3b‑ol]. It was demonstrated that Atg7 expression was upregulated from day 1 of diosgenin‑induced differentiation and was accompanied by a significant elevation in the conversion of light chain 3 A/B (LC3‑A/B)‑I to LC3‑A/B‑II. Autophagy was modulated before or after the induction of megakaryocyte differentiation using 3‑methyladenine (3‑MA, autophagy inhibitor) and metformin (Met, autophagy initiation activator). 3‑MA induced a significant accumulation of the LC3 A/B‑II form at day 8 of differentiation. It was revealed that 3‑MA had a significant repressive effect on the nuclear (polyploidization) and membrane glycoprotein V [(GpV) expression] maturation. On the other hand, autophagy activation increased GpV genomic expression, but did not change the nuclear maturation profile after HEL cells treatment with Met. It was concluded that autophagy inhibition had a more prominent effect on the diosgenin‑differentiated cells than autophagy activation.

Effects of Selected Nigerian Medicinal Plants on the Viability, Mobility, and Multidrug-Resistant Mechanisms in Liver, Colon, and Skin Cancer Cell Lines

Medicinal plants indicated for chronic diseases usually have good safety margins as they are intended for lifelong treatments. We hypothesized that they may provide patients with baseline protection to cancers and multidrug resistance-reversing phytochemicals resulting in successful prevention and/or adjuvant treatment of chemotherapy-resistant cancers. We selected 27 popular herbal infusions widely used in Nigeria for diabetes and studied their effects on a panel of liver (HepG2), colon (Caco2), and skin (B16-F10) cancer cells. Cytotoxicity was measured using the SRB staining assay. The 2D antimigratory effect was evaluated using an Oris™ platform. The P-glycoprotein (P-gp) efflux activity was evaluated using Rh-123 as a fluorescent probe. The inhibition of tyrosinase-mediated melanogenesis was evaluated by colorimetric enzymatic assays. Our results show that melanoma cell proliferation was strongly inhibited by Anogeissus leiocarpus (Combretaceae), Bridelia ferruginea (Phyllanthaceae), D. ogea (Leguminosae), and Syzygium guineense (Myrtaceae) extracts (G_{I50 =} 50 µg/ml). Alstonia boonei (Apocynaceae), Gongronema latifolium (Asclepiadaceae), and Strophanthus hispidus (Apocynaceae) were preferentially toxic against Caco2 (GI_{50 =} 50, 5 and 35 µg/ml, respectively). The most active extracts against different drug resistance mechanisms were B. ferruginea (inhibition of P-gp efflux, and impairing tyrosinase activity) and X. americana (inhibition of P-gp efflux). A. leiocarpus, Kaya senegalensis (Meliaceae), S. guineense, and Terminalia avicennioides (Combretaceae) significantly inhibited B16-F10 cell migration. Lupeol, ursolic acid, quercitrin, epicatechin, gallic acid, and ellagic acid were dereplicated by HPLC and HPTLC as their bioactive phytochemicals. In conclusion, the above in-vitro activities of herbal infusions regularly consumed by Nigerian diabetic patients may either act as a baseline chemoprotection or as sensitizing agents.

Who's in charge here? Macrophage colony stimulating factor and granulocyte macrophage colony stimulating factor: Competing factors in macrophage polarization

Macrophages make up a crucial aspect of the immune system, carrying out a variety of functions ranging from clearing cellular debris to their well-recognized roles as innate immune cells. These cells exist along a spectrum of phenotypes but can be generally divided into proinflammatory (M1) and anti-inflammatory (M2) groups, representing different states of polarization. Due to their diverse functions, macrophages are implicated in a variety of diseases such as atherosclerosis, lupus nephritis, or infection with HIV. Throughout their lifetime, macrophages can be influenced by a wide variety of signals that influence their polarization states, which can affect their function and influence their effects on disease progression. This review seeks to provide a summary of how GM-CSF and M-CSF influence macrophage activity during disease, and provide examples of in vitro research that indicate competition between the two cytokines in governing macrophage polarization. Gaining a greater understanding of the relationship between GM-CSF and M-CSF, along with how these cytokines fit into the larger context of diseases, will inform their use as treatments or targets for treatment in various diseases.

Nilotinib induction of melanogenesis via reactive oxygen species-dependent JNK activation in B16F0 mouse melanoma cells

Nilotinib (AMN), a second-generation tyrosine kinase inhibitor, induces apoptosis in various cancer cells, and our recent study showed that AMN effectively reduced the viability of human ovarian cancer cells via mitochondrion-dependent apoptosis. The effect of AMN in the melanogenesis of melanoma cells is still unclear. In the present study, we found that the addition of AMN but not imatinib (STI) significantly increased the darkness of B16F0 melanoma cells, and the absorptive value increased with the concentration of AMN. A decrease in the viability of B16F0 cells by AMN was detected in a concentration-dependent manner, accompanied by increased DNA ladders, hypodiploid cells and cleavage of the caspase-3 protein. An in vitro tyrosinase (TYR) activity assay showed that increased TYR activity by AMN was detected in a concentration-dependent manner; however, induction of TYR activity by STI at a concentration of 40 μmol/L was observed. Increased intracellular peroxide by AMN was detected in B16F0 cells, and application of the antioxidant, N-acetylcysteine (NAC), significantly reduced AMN-induced peroxide production which also reduced the darkness of B16F0 cells. Additionally, AMN induced c-Jun N-terminal kinase (JNK) protein phosphorylation in B16F0 cells, which was inhibited by the addition of NAC. AMN-induced melanogenesis of B16F0 cells was significantly inhibited by the addition of NAC and the JNK inhibitor, SP600125 (SP). Data of Western blotting showed that increased protein levels of melanogenesis-related enzymes of tyrosinase-related protein-1 (TRP1), TRP2 and TYR were observed in AMN-treated B16F0 cells which were inhibited by the addition of NAC and SP. Evidence is provided supporting AMN effectively inducing the melanogenesis of B16F0 melanoma cells via reactive oxygen species-dependent JNK activation.

Unraveling the molecular mechanisms and the potential chemopreventive/therapeutic properties of natural compounds in melanoma

Melanoma is the most fatal form of skin cancer. Current therapeutic approaches include surgical resection, chemotherapy, targeted therapy and immunotherapy. However, these treatment strategies are associated with development of drug resistance and severe side effects. In recent years, natural compounds have also been extensively studied for their anti-melanoma effects, including tumor growth inhibition, apoptosis induction, angiogenesis and metastasis suppression and cancer stem cell elimination. Moreover, a considerable number of studies reported the synergistic activity of phytochemicals and standard anti-melanoma agents, as well as the enhanced effectiveness of their synthetic derivatives and novel formulations. However, clinical data confirming these promising effects in patients are still scanty. This review emphasizes the anti-tumor mechanisms and potential application of the most studied natural products for melanoma prevention and treatment.

Antitumoral, antioxidant, and antimelanogenesis potencies of Hawthorn, a potential natural agent in the treatment of melanoma

The lack of an efficient agent that does not have the disadvantage of low activity (kojic acid), high cytotoxicity, and mutagenicity (hydroquinone), poor skin penetration (arbutin), or low stability in formulation (glabridin) led us to continue our research on new antipigmentation/skin-lightening agents. Therefore, research of natural products that can modulate the metabolism of pigmentation is of great interest. Otherwise, malignant melanoma is one of the most aggressive forms of skin cancer, with high metastatic potential, and currently, there is no effective chemotherapy against invasive melanoma. Therefore, it is necessary to develop new drugs with potent activity and weak side effects against melanoma. The in-vitro anticancer effect of hawthorn was analyzed against B16F10 melanoma cells using a 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay. The effect of isolated compounds from hawthorn on melanogenesis in B16F10 melanoma cells was investigated by measuring the amounts of melanin and tyrosinase spectrophotometrically at 475 nm. Balb/c mice models inoculated with B16F10 mouse tumor cells were used to evaluate the in-vivo antitumoral potential of hawthorn by assessing its effect on the growth of transplanted tumors. The antioxidant potential of tested samples was evaluated in B16F10 and primary human keratinocyte cells using a cellular antioxidant activity assay. Hawthorn tested samples inhibited effectively the growth of melanoma cells in vitro. Furthermore, it appears that tested samples from hawthorn reduced melanogenesis by inhibiting the tyrosinase activity of B16F10 cells in a dose-dependent manner. In-vivo studies showed that hawthorn total oligomer flavonoids extract treatment at a dose of 150 mg/kg body weight for 21 days in implanted tumor mice resulted in significant inhibition of the tumor growth volume and weight. In addition, tested samples showed significant cellular antioxidant capacity against the reactive oxygen species in B16F10 and primary human keratinocyte cells. Our results indicate that hawthorn could be considered as a promising agent for the treatment of melanoma as it shows antitumor activity in vitro and in vivo. Moreover, hawthorn constituents are shown to be highly effective at inhibiting tyrosinase-mediated melanogenesis in vitro on melanoma cells by preventing oxidation in these cells and without affecting the viability of normal human keratinocyte cells. Then, hawthorn might also be used as a new candidate of natural skin depigmenting agents in skin care products.

Effects of protein hydrolysate from chicken feather meal on tyrosinase activity and melanin formation in B16F10 murine melanoma cells

Tyrosinase is a copper-containing enzyme that controls mammalian melanogenesis. Tyrosinase inhibitors are important for their potential application in cosmetic products. Chicken feather meal is a rich source of amino acids, which have been linked with tyrosinase inhibition activity. This study investigated the tyrosinase inhibitory properties of protein hydrolysates prepared from chicken feather meal. Protein hydrolysates prepared by pepsin-pancreatin with MW <3 kDa exhibited strong tyrosinase inhibition activity for both monophenolase (IC50 5.780 ± 0.188 µg/mL) and diphenolase activities (IC50 0.040 ± 0.024 µg/mL) in a cell-free mushroom tyrosinase system. These samples were uncompetitive inhibitors with Ki values of 18.149 and 27.189 µg/mL in monophenolase and diphenolase activities, respectively. A cell culture model showed that this hydrolysate had the strongest inhibition on the viability of B16F10 cells (IC50 1.124 ± 0.288 µg/mL) and 0.210 µg/mL of the sample exhibited inhibition of tyrosinase activity by 50.493% and melanin synthesis by 14.680% compared to the control.

EFFECT OF FUCOIDAN ON B16 MURINE MELANOMA CELL MELANIN FORMATION AND APOPTOSIS

Background: :

Fucoidan is a complex sulfated polysaccharide extracted from brown seaweed and has a wide variety of biological activities. It not only inhibits cancer cell growth but also inhibits tyrosinase in vitro. Therefore, it is of interest to investigate the effect of fucoidan on B16 murine melanoma cells as the findings may provide new insights into the underlying mechanism regarding the inhibition of melanin formation by fucoidan. In the present study, we aimed to investigate the anti-melanogenic effect of fucoidan and its inhibitory effect on B16 cells.

Materials and Methods:

The influence of fucoidan on B16 melanoma cells and cellular tyrosinase was examined. Cell viability was examined by the cell counting kit-8 assay. Cellular tyrosinase activity and melanin content were determined using spectrophotometric methods and protein expression was analyzed by immunoblotting. Morphological changes in B16 melanoma cells were examined by phase contrast microscopy and apoptosis was analyzed by flow cytometry.

Results:

In vitro studies were performed using cell viability analysis and showed that fucoidan significantly decreased viable cell number in a dose-response manner with an IC₅₀ of 550 ±4.3 µg/mL. Cell morphology was altered and significant apoptosis was induced when cells were exposed to 550 µg/mL fucoidan for 48 h.

Conclusion:

This study provides substantial evidence to show that fucoidan inhibits B16 melanoma cell proliferation and cellular tyrosinase activity. Fucoidan may be useful in the treatment of hyperpigmentation and as a skin-whitening agent in the cosmetics industry.

Polyethylenimine-dermatan sulfate complex, a bioactive biomaterial with unique toxicity to CD146-positive cancer cells

We report unique bioactivity of a polycation-polyanion complex with potential utility for cancer therapy. A complex of disulfide-crosslinked polyethyleneimine (CLPEI), a polycation used for gene complexation, and dermatan sulfate (DS), an anionic polysaccharide to shield excessive cationic charge of the former, has toxicity to a specific group of cancer cell lines, including B16-F10 murine melanoma, A375SM human melanoma, and PC-3 human prostate cancer cells. These CLPEI-DS-sensitive cells express CD146, which binds to the complex via interaction with DS. There is a positive correlation between toxicity and intracellular level of CLPEI, indicating that the CLPEI-DS-sensitivity is attributable to the increased cellular uptake of CLPEI mediated by the DS-CD146 interactions. In vitro studies show that CLPEI-DS complex causes G₀/G₁ phase arrest and apoptotic cell death. In syngeneic and allograft models of B16-F10 melanoma, CLPEI-DS complex administered with a sub-toxic level of doxorubicin potentiates the chemotherapeutic effect of the drug by loosening tumor tissues. Given the unique toxicity, CLPEI-DS complex may be a useful carrier of gene or chemotherapeutics for the therapy of CD146-positive cancers.

Molecular docking studies and biological evaluation of 1,3,4-thiadiazole derivatives bearing Schiff base moieties as tyrosinase inhibitors

1,3,4-Thiadiazole derivatives bearing Schiff base moieties were designed, synthesized, and their tyrosinase inhibitory activities were evaluated. Some compounds displayed potent tyrosinase inhibitory activities, especially, 4-(((5-mercapto-1,3,4-thiadiazol-2-yl)-imino)methyl)-2-methoxy-phenol (14) exhibited superior inhibitory effect to the other compounds with an IC₅₀ value of 0.036μM. The structure-activity relationships (SARs) were preliminarily discussed and docking studies showed compound 14 had strong binding affinity to mushroom tyrosinase. Hydroxy might be the active groups. The inhibition kinetics study revealed that compounds (13 and 14) inhibited tyrosinase by acting as uncompetitive inhibitors. The LD₅₀ value of the compound 14 was 5000mg/kg.

Resistance to ursolic acid-induced apoptosis through involvement of melanogenesis and COX-2/PGE2 pathways in human M4Beu melanoma cancer cells

Melanoma is one of the most aggressive forms of cancer with a continuously growing incidence worldwide and is usually resistant to chemotherapy agents, which is due in part to a strong resistance to apoptosis. Previously, we had showed that B16-F0 murine melanoma cells undergoing apoptosis are able to delay their own death induced by ursolic acid (UA), a natural pentacyclic triterpenoid compound. We had demonstrated that tyrosinase and TRP-1 up-regulation in apoptotic cells and the subsequent production of melanin were implicated in an apoptosis resistance mechanism. Several resistance mechanisms to apoptosis have been characterized in melanoma such as hyperactivation of DNA repair mechanisms, drug efflux systems, and reinforcement of survival signals (PI3K/Akt, NF-κB and Raf/MAPK pathways). Otherwise, other mechanisms of apoptosis resistance involving different proteins, such as cyclooxygenase-2 (COX-2), have been described in many cancer types. By using a strategy of specific inhibition of each ways, we suggested that there was an interaction between melanogenesis and COX-2/PGE2 pathway. This was characterized by analyzing the COX-2 expression and activity, the expression of tyrosinase and melanin production. Furthermore, we showed that anti-proliferative and proapoptotic effects of UA were mediated through modulation of multiple signaling pathways including Akt and ERK-1/2 proteins. Our study not only uncovers underlying molecular mechanisms of UA action in human melanoma cancer cells but also suggest its great potential as an adjuvant in treatment and cancer prevention.

Para-Phenylenediamine Induces Apoptotic Death of Melanoma Cells and Reduces Melanoma Tumour Growth in Mice

Melanoma is one of the most aggressive forms of cancer, usually resistant to standard chemotherapeutics. Despite a huge number of clinical trials, any success to find a chemotherapeutic agent that can effectively destroy melanoma is yet to be achieved. Para-phenylenediamine (p-PD) in the hair dyes is reported to purely serve as an external dyeing agent. Very little is known about whether p-PD has any effect on the melanin producing cells. We have demonstrated p-PD mediated apoptotic death of both human and mouse melanoma cells in vitro. Mouse melanoma tumour growth was also arrested by the apoptotic activity of intraperitoneal administration of p-PD with almost no side effects. This apoptosis is shown to occur primarily via loss of mitochondrial membrane potential (MMP), generation of reactive oxygen species (ROS), and caspase 8 activation. p-PD mediated apoptosis was also confirmed by the increase in sub-G0/G1 cell number. Thus, our experimental observation suggests that p-PD can be a potential less expensive candidate to be developed as a chemotherapeutic agent for melanoma.

Synthesis and effects of oxadiazole derivatives on tyrosinase activity and human SK-MEL-28 malignant melanoma cells

Melanin is a form of pigment that gives colour to human skin, hair and eyes.

Apple Pomace Extract Improves Endurance in Exercise Performance by Increasing Strength and Weight of Skeletal Muscle

Ursolic acid is a lipophilic pentacyclic triterpenoid found in many fruits and herbs and is used in several herbal folk medicines for diabetes. In this study, we evaluated the effects of apple pomace extract (APE; ursolic acid content, 183 mg/g) on skeletal muscle atrophy. To examine APE therapeutic potential in muscle atrophy, we investigated APE effects on the expression of biomarkers associated with muscle atrophy and hypertrophy. We found that APE inhibited atrophy, while inducing hypertrophy in C2C12 myotubes by decreasing the expression of atrophy-related genes and increasing the expression of hypertrophy-associated genes. The in vivo experiments using mice fed a diet with or without APE showed that APE intake increased skeletal muscle mass, as well as grip strength and exercise capacity. In addition, APE significantly improved endurance in the mice, as evidenced by increased exhaustive running time and muscle weight, and reduced the expression of the genes involved in the development of muscle atrophy. APE also decreased the concentration of serum lactate and lactate dehydrogenase, inorganic phosphate, and creatinine, the indicators of accumulated fatigue and exercise-induced stress. These results suggest that APE may be useful as an ergogenic functional food or dietary supplement.

Design and synthesis of aloe-emodin derivatives as potent anti-tyrosinase, antibacterial and anti-inflammatory agents

Twenty aloe-emodin derivatives were designed, synthesized, and their biological activities were evaluated. Some compounds displayed potent tyrosinase inhibitory activities, especially, compounds with thiosemicarbazide moiety showed more potent inhibitory effects than the other compounds. The structure-activity relationships (SARs) were preliminarily discussed. The inhibition mechanism of selected compounds 1 and 13 were investigated. The results showed compound 1 was reversible inhibitor, however, compound 13 was irreversible. Kinetic analysis indicated that compound 1 was competitive tyrosinase inhibitor. Furthermore, the antibacterial activities and anti-inflammatory activities of some selected compounds were also screened. The results showed that compound 3 exhibited more potent antibacterial activity than the aloe-emodin, compounds 5 and 6 possessed more potent anti-inflammatory activities than the diacerein.

Behaviour of four different B16 murine melanoma cell sublines: C57BL/6J skin

Transplantable murine melanomas are well-established models for the study of experimental cancer therapies. The aim of this study was to explore the behaviour of four different B16 murine melanoma cell sublines after inoculation into C57BL/6J mice; and, more specifically to analyse skin changes, with respect to two specific parameters: clinical (tumour volume, melanin amount, erythema) and histological (H & E, S100, VEGF expression). Both non-invasive and invasive analysis showed that B164A5 is the most aggressive melanoma cell line for C57BL/6J's skin, followed by B16F10 and then by diminished aggressive growth pattern by the B16GMCSF and B16FLT3 cell lines.

Compounds isolated from the aerial part of Crataegus azarolus inhibit growth of B16F10 melanoma cells and exert a potent inhibition of the melanin synthesis

Poor therapeutic results have been reported for treatment of malignant melanoma; therefore in this study, we have investigated inhibitory capacity of vitexin-2''-O-rhamnoside as well as the extract from which it was isolated, i.e. the ethyl acetate extract obtained from the leaves of Crataegus azarolus, on mouse melanoma (B16F10) proliferation. Cell viability was determined using the 3-(4, 5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay. In addition, amounts of melanin and tyrosinase were measured spectrophotometrically at 475nm. Ethyl acetate extract and vitexin-2''-O-rhamnoside exhibited significant anti-proliferative activity against B16F10 melanoma cells after incubation for 48hours with IC50s of 50μg/mL and 20μM, respectively. Furthermore, these two compounds have the ability to reduce the melanin content by inhibiting the tyrosinase activity of B16F10 cells. Thus, further investigations are merited to ascertain their potential application in treating hyperpigmentation disorders.

Chinese medicines induce cell death: the molecular and cellular mechanisms for cancer therapy

Chinese medicines have long history in treating cancer. With the growing scientific evidence of biomedical researches and clinical trials in cancer therapy, they are increasingly accepted as a complementary and alternative treatment. One of the mechanisms is to induce cancer cell death. Aim. To comprehensively review the publications concerning cancer cell death induced by Chinese medicines in recent years and provide insights on anticancer drug discovery from Chinese medicines. Materials and Methods. Chinese medicines (including Chinese medicinal herbs, animal parts, and minerals) were used in the study. The key words including “cancer”, “cell death”, “apoptosis”, “autophagy,” “necrosis,” and “Chinese medicine” were used in retrieval of related information from PubMed and other databases. Results. The cell death induced by Chinese medicines is described as apoptotic, autophagic, or necrotic cell death and other types with an emphasis on their mechanisms of anticancer action. The relationship among different types of cell death induced by Chinese medicines is critically reviewed and discussed. Conclusions. This review summarizes that CMs treatment could induce multiple pathways leading to cancer cell death, in which apoptosis is the dominant type. To apply these preclinical researches to clinic application will be a key issue in the future.

Sonic Hedgehog activation is implicated in diosgenin-induced megakaryocytic differentiation of human erythroleukemia cells

Differentiation therapy is a means to treat cancer and is induced by different agents with low toxicity and more specificity than traditional ones. Diosgenin, a plant steroid, is able to induce megakaryocytic differentiation or apoptosis in human HEL erythroleukemia cells in a dose-dependent manner. However, the exact mechanism by which diosgenin induces megakaryocytic differentiation has not been elucidated. In this study, we studied the involvement of Sonic Hedgehog in megakaryocytic differentiation induced by diosgenin in HEL cells. First, we showed that different elements of the Hedgehog pathway are expressed in our model by qRT-PCR. Then, we focused our interest on key elements in the Sonic Hedgehog pathway: Smoothened receptor, GLI transcription factor and the ligand Sonic Hedgehog. We showed that Smoothened and Sonic Hedgehog were overexpressed in disogenin-treated cells and that GLI transcription factors were activated. Then, we showed that SMO inhibition using siSMO or the GLI antagonist GANT-61, blocked megakaryocytic differentiation induced by diosgenin in HEL cells. Furthermore, we demonstrated that Sonic Hedgehog pathway inhibition led to inhibition of ERK1/2 activation, a major physiological pathway involved in megakaryocytic differentiation. In conclusion, our study reports, for the first time, a crucial role for the Sonic Hedgehog pathway in diosgenin-induced megakaryocytic differentiation in HEL cells.

Cyclopamine and jervine induce COX-2 overexpression in human erythroleukemia cells but only cyclopamine has a pro-apoptotic effect

Erythroleukemia is generally associated with a very poor response and survival to current available therapeutic agents. Cyclooxygenase-2 (COX-2) has been described to play a crucial role in the proliferation and differentiation of leukemia cells, this enzyme seems to play an important role in chemoresistance in different cancer types. Previously, we demonstrated that diosgenin, a plant steroid, induced apoptosis in HEL cells with concomitant COX-2 overexpression. In this study, we investigated the antiproliferative and apoptotic effects of cyclopamine and jervine, two steroidal alkaloids with similar structures, on HEL and TF1a human erythroleukemia cell lines and, for the first time, their effect on COX-2 expression. Cyclopamine, but not jervine, inhibited cell proliferation and induced apoptosis in these cells. Both compounds induced COX-2 overexpression which was responsible for apoptosis resistance. In jervine-treated cells, COX-2 overexpression was NF-κB dependent. Inhibition of NF-κB reduced COX-2 overexpression and induced apoptosis. In addition, cyclopamine induced apoptosis and COX-2 overexpression via PKC activation. Inhibition of the PKC pathway reduced both apoptosis and COX-2 overexpression in both cell lines. Furthermore, we demonstrated that the p38/COX-2 pathway was involved in resistance to cyclopamine-induced apoptosis since p38 inhibition reduced COX-2 overexpression and increased apoptosis in both cell lines.

The P2Y2/Src/p38/COX-2 pathway is involved in the resistance to ursolic acid-induced apoptosis in colorectal and prostate cancer cells

One of the hallmarks of cancer is resistance to apoptosis. Elucidating the mechanisms of how cancer cells evade or delay apoptosis should lead to novel therapeutic strategies. Previously, we showed that HT-29 colorectal cancer cells undergoing apoptosis overexpressed cyclooxygenase-2 (COX-2), in a p38 dependent pathway, to delay ursolic acid-induced apoptosis. Here, we focused on elucidating the upstream signaling pathways regulating this resistance mechanism. The role of ATP as an extracellular signaling molecule took a long time to be accepted. In recent years, ATP and its analogs, via the activation of specific purinergic receptors, have been implicated in many biological processes including cell proliferation, differentiation and apoptosis. In the present report, we have demonstrated a novel role involving purinergic receptors and particularly the P2Y(2) receptor in resistance to ursolic acid-induced apoptosis in both colorectal HT-29 and prostate DU145 cancer cells. We found that ursolic acid induced an increase in intracellular ATP and P2Y(2) transcript levels. Upon activation, P2Y(2) activated Src which in turn phosphorylated p38 leading to COX-2 overexpression which induced resistance to apoptosis in both HT-29 and DU145 cells. Furthermore, Ca(2+)-independent PLA(2) (iPLA(2)) and Ca(2+)-dependent secretory PLA(2) (sPLA(2)) were responsible for arachidonic acid release, the substrate of COX-2. Our findings document that apoptosis triggering was dependent on protein kinase C (PKC) activation in both cell lines after ursolic acid treatment.

Ursolic acid directly promotes protein accretion in myotubes but does not affect myoblast proliferation

Ursolic acid (UA) has been recently proposed as a potential candidate for the treatment of muscle wasting conditions because of its protein sparring/anabolic effects. Despite this finding, it is unknown whether this response is the consequence of a direct effect on the muscle fibre or if it is mediated by neural or other systemic factors. In the present study, we sought to determine if UA has direct effects in skeletal muscle cells, whether it can increase myoblast proliferation and whether UA can become myotoxic at higher doses. Our results demonstrate that UA directly promoted protein accretion in cultured myotubes but did not modulate myoblast proliferation. At higher doses, UA compromised cell viability in both myoblasts and myotubes. We conclude that the anabolic properties of UA seen in vivo and in vitro are likely a direct effect on the muscle cell, but at higher doses, the benefits decline in favour of a myotoxic outcome.

Mn loaded apoferritin as an MRI sensor of melanin formation in melanoma cells

Mn(III)-loaded apoferritin is promptly reduced to Mn(II)-apoferritin by the oxidation of L-DOPA to melanin. The process is nicely witnessed by a marked relaxation enhancement of water proton relaxation rate that has been detected both in cultured melanoma cells and in tumor animal models.