Wojciech Krol

Ethanolic extract of Brazilian green propolis sensitizes prostate cancer cells to TRAIL-induced apoptosis

Prostate cancer represents an ideal disease for chemopreventive intervention. Propolis possesses immuno-modulatory, anti-tumour and chemopreventive properties. The tumour necrosis factor-related apoptosis-inducing ligand (TRAIL) is an important endogenous anti-cancer agent that induces apoptosis selectively in tumour cells. However, some cancer cells are resistant to TRAIL-mediated apoptosis. Naturally occurring phenolic and polyphenolic compounds sensitize TRAIL-resistant cancer cells and augment the apoptotic activity of TRAIL. The ethanolic extract of Brazilian green propolis (EEP) is rich in phenolic components. Our in vitro results indicate the potential targets in the TRAIL-induced apoptotic pathway for the cancer chemopreventive activity of Brazilian propolis. We examined the cytotoxic and apoptotic effects of Brazilian EEP and its bioactive components in combination with TRAIL on LNCaP prostate cancer cells. The chemical composition of Brazilian green propolis was determined by high performance liquid chromatography-diode array detection. The cytotoxicity was measured by 3-[4,5-dimethylthiazol-2-yl]-2,5 diphenyl-tetrazolium and lactate dehydrogenase assays. Apoptosis was detected using annexin V-FITC by flow cytometry and fluorescence microscopy. The mitochondrial membrane potential (∆Ψm) was evaluated using DePsipher staining by fluorescence microscopy. Flow cytometry was used to analyse death receptor (TRAIL-R1 and TRAIL-R2) expression in LNCaP cells. The inhibition of nuclear factor-κB (NF-κB) (p65) activation in cancer cells was confirmed by the ELISA-based TransAM NF-κB kit. The LNCaP cells were shown to be resistant to TRAIL-induced apoptosis. Our study demonstrates that EEP sensitizes TRAIL-resistant prostate cancer cells. The main phenolic components detected in Brazilian green propolis are artepillin C, quercetin, kaempferol and p-coumaric acid. Brazilian propolis and its bioactive components markedly augmented TRAIL-mediated apoptosis and cytotoxicity in prostate cancer cells. Brazilian EEP enhanced the expression of TRAIL-R2 and the activity of NF-κB in LNCaP cells. The co-treatment of prostate cancer cells with 100 ng/ml TRAIL and 50 µg/ml EEP increased the percentage of apoptotic cells to 65.8 ± 1.2% and caused a significant disruption of ∆Ψm in LNCaP cells. We show that Brazilian EEP helped cells overcome TRAIL resistance by engaging both intrinsic and extrinsic apoptotic pathways and regulating NF-κB activity. The data demonstrate the important role of Brazilian green propolis and its bioactive compounds in prostate cancer chemoprevention through the enhancement of TRAIL-mediated apoptosis.

Enhanced TRAIL-mediated apoptosis in prostate cancer cells by the bioactive compounds neobavaisoflavone and psoralidin isolated from Psoralea corylifolia

Numerous compounds detected in medical plants and dietary components or supplements possess chemopreventive, antitumor and immunomodulatory properties. Tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) is an important endogenous anticancer factor that induces apoptosis selectively in cancer cells. However, some tumor cells are resistant to TRAIL-mediated apoptosis. Naturally occurring agents could sensitize TRAIL-resistant cancer cells and augment their apoptotic activity.We examined the cytotoxic and apoptotic effects of neobavaisoflavone and psoralidin in combination with TRAIL on LNCaP prostate cancer cells. The cytotoxicity was evaluated by MTT and LDH assays. The apoptosis was detected using Annexin V-FITC by flow cytometry and fluorescence microscopy. The LNCaP cells were shown to be resistant to TRAIL-induced apoptosis. Our study demonstrated that neobavaisoflavone and psoralidin sensitized TRAIL-resistant cells and markedly augmented TRAIL-mediated apoptosis and cytotoxicity in prostate cancer cells. Cotreatment of LNCaP cells with 100 ng/ml TRAIL and 50 μM neobavaisoflavone or 50 μM psoralidin increased the percentage of the apoptotic cells to 77.5±0.5% or 64.4±0.5%, respectively. The data indicate the potential role of the bioactive compounds isolated from the medicinal plant Psoralea corylifolia (neobavaisoflavone and psoralidin) in prostate cancer chemoprevention through enhancement of TRAIL-mediated apoptosis.

The dietary flavonol fisetin enhances the apoptosis-inducing potential of TRAIL in prostate cancer cells

Tumour necrosis factor-related apoptosis-inducing ligand (TRAIL) is an endogenous agent that induces apoptosis selectively in cancer cells. Soluble or expressed in immune cells, TRAIL plays an important role in the defense against tumour cells. The resistance of cancer cells to TRAIL immune surveillance is implicated in tumour development. Naturally occurring flavonoids can sensitize TRAIL-resistant cancer cells and augment their apoptotic activity. Fisetin, a dietary flavonol has cancer preventive properties. This study was designed to investigate the effect of fisetin on the TRAIL-induced apoptosis potential in prostate cancer cells. Prostate cancer cell lines represent an ideal model for research in chemoprevention. Cytotoxicity was measured by MTT and LDH assays. Apoptosis was detected using Αnnexinxa0V-FITC by flow cytometry and fluorescence microscopy. Mito-chondrial membrane potential (ΔΨm) was evaluated using DePsipher staining by fluorescence microscopy. Death receptor (TRAIL-R1 and TRAIL-R2) expression was analysed by flow cytometry. Inhibition of NF-κB (p65) activation was confirmed with an ELISA-based TransAM NF-κB kit. Caspase-8 and caspase-3 activities were determined by colorimetric protease assays. Our study demonstrates that fisetin sensitizes the TRAIL-resistant androgen-dependent LNCaP and the androgen-independent DU145 and PC3 prostate cancer cells to TRAIL-induced death. Fisetin augmented TRAIL-mediated cytotoxicity and apoptosis in prostate cancer LNCaP cells by engaging the extrinsic (receptor-mediated) and intrinsic (mitochondrial) apoptotic pathways. Fisetin increased the expression of TRAIL-R1 and decreased the activity of NF-κB. Co-treatment of cancer cells with TRAIL and fisetin caused significant activation of caspase-8 and caspase-3 and disruption of ΔΨm. Our data indicate the usefulness of fisetin in prostate cancer chemoprevention through enhancement of TRAIL-mediated apoptosis.

Artepillin C (3,5-diprenyl-4-hydroxycinnamic acid) sensitizes LNCaP prostate cancer cells to TRAIL-induced apoptosis

Naturally occurring phenolic compounds have been shown to sensitize prostate cancer cells to tumour necrosis factor-related apoptosis-inducing ligand (TRAIL)-induced apoptosis. TRAIL is a potent stimulator of apoptosis in cancer cells and an important immune effector molecule in the surveillance and elimination of developing tumours. However, many cancer cells are resistant to TRAIL-mediated death. In this study, we aimed to determine the mechanisms by which TRAIL resistance can be overcome in prostate cancer cells by 3,5-diprenyl-4-hydroxycinnamic acid (artepillin C). Artepillin C is a bioactive component of Brazilian green propolis that possesses antitumour and chemopreventive activities. TRAIL-resistant LNCaP prostate cancer cells were treated with TRAIL and artepillin C. Cytotoxicity was measured by MTT and lactate dehydrogenase (LDH) assays. Apoptosis was detected using Annexin V-FITC staining by flow cytometry and fluorescence microscopy. Death receptor (DR) (TRAIL-R1/DR4 and TRAIL-R2/DR5) expression was analyzed using flow cytometry. Mitochondrial membrane potential (ΔΨm) was evaluated using DePsipher staining by fluorescence micro scopy. The inhibition of NF-κB (p65) activation was confirmed with the ELISA-based TransAM NF-κB kit. Caspase-8 and caspase-3 activities were determined by colorimetric protease assays. The results showed that artepillin C sensitized the TRAIL-resistant LNCaP cells by engaging the extrinsic (receptor-mediated) and intrinsic (mitochondrial) apoptotic pathways. Artepillin C increased the expression of TRAIL-R2 and decreased the activity of NF-κB. Co-treatment with TRAIL and artepillin C induced the significant activation of caspase-8 and caspase-3, as well as the disruption of ΔΨm. These findings show that prostate cancer cells can be sensitized to TRAIL-mediated immunoprevention by artepillin C and confirm the role of phenolic compounds in prostate cancer immunochemoprevention.

Soy isoflavones augment the effect of TRAIL-mediated apoptotic death in prostate cancer cells.

Prostate cancer represents an ideal disease for chemopreventive intervention. Genistein, daidzein and equol, the predominant soy isoflavones, have been reported to lower the risk of prostate cancer. Isoflavones exert their chemopreventive properties by affecting apoptosis signalling pathways in cancer cells. Tumour necrosis factor-related apoptosis-inducing ligand (TRAIL) is an endogenous anticancer agent that induces apoptosis selectively in tumour cells. Soluble or expressed in immune cells, TRAIL molecules play an important role in immune surveillance and defense mechanisms against tumour cells. However, various types of cancer cells are resistant to TRAIL-mediated apoptosis. We examined the cytotoxic and apoptotic effects of genistein, daidzein and equol in combination with TRAIL in LNCaP cells. Cytotoxicity was measured by MTT and LDH assays. Apoptosis was analyzed by flow cytometry and fluorescence microscopy using Annexin V-FITC. Mitochondrial membrane potential (ΔΨm) was evaluated by fluorescence microscopy using DePsipher staining. Flow cytometry detected the expression of death receptor TRAIL-R1 (DR4) and TRAIL-R2 (DR5) on cell surfaces. The soy isoflavones sensitized TRAIL-resistant prostate cancer cells to apoptotic death. The isoflavones did not alter death receptor expression, but significantly augmented TRAIL-induced disruption of ΔΨm in the LNCaP cells. We showed for the first time that the chemopreventive effects of soy foods on prostate cancer are associated with isoflavone-induced support of TRAIL-mediated apoptotic death.

The dietary isoflavone biochanin-A sensitizes prostate cancer cells to TRAIL-induced apoptosis

Biochanin-A, a major dietary isoflavone in soy and red clover, possesses anticancer and chemopreventive properties. Induction of apoptosis by naturally occurring dietary agents is an important event for cancer chemoprevention. Tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) triggers apoptosis selectively in cancer cells but not in normal cells. Soluble or expressed in immune cells, molecules TRAIL plays a significant role in surveillance and defense mechanisms against tumours. Prostate cancer is an ideal disease for nutritional prevention. The TRAIL-mediated apoptosis pathway in prostate cancer cells is an attractive target for chemopreventive activities of dietary agents. LNCaP and DU145 prostate cancer cells are resistant to TRAIL-induced apoptosis. We showed that biochanin-A markedly augmented TRAIL-induced cytotoxicity and apoptosis in both prostate cancer cell lines. Then, we investigated the mechanisms by which biochanin-A enhanced TRAIL-mediated apoptosis using the LNCaP cell line. The isoflavone sensitized the TRAIL-resistant LNCaP cells through the inhibition of transcription factor NF-κB(p65) activity, increased the expression of the death receptor TRAIL-R2 (DR5), and disrupted mitochondrial membrane potential (ΔΨm). Our study confirmed that biochanin-A overcame TRAIL-resistance by engaging both intrinsic and extrinsic apoptotic pathways and by regulating the NF-κB activity. The results suggested a potential role of biochanin-A in prostate cancer chemoprevention through the enhancement of TRAIL-mediated apoptosis.

Chlorin-based photodynamic therapy enhances the effect of tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) in bladder cancer cells

Summary Background Photodynamic therapy (PDT) is an attractive, emerging therapeutic procedure suitable for the treatment of non-muscle-invasive bladder cancer. Tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) is a death ligand that belongs to the TNF superfamily of cytokines. The ability of TRAIL to selectively induce apoptosis in cancer cells but not in normal cells promotes the development of TRAIL-based cancer therapy. However, many tumor cells are resistant to TRAIL-induced apoptosis. The purpose of the study was to overcome TRAIL-resistance in bladder cancer cells by photodynamic therapy (PDT). Material/Methods Three human bladder transitional cancer cell lines – T24, 647V and SW780 – were treated with TRAIL and/or chlorin-based PDT. The cytotoxicity was measured by MTT and LDH assays and apoptosis was detected using annexin V by flow cytometry. Results Our test confirmed that T24 and 647V bladder cancer cells are resistant to TRAIL, whereas SW780 cells are sensitive to TRAIL. Then we examined the cytotoxic and apoptotic effects of TRAIL in combination with chlorin e6-polyvinylpyrrolidone (Ce6-PVP)-mediated PDT on bladder cancer cells. We showed for the first time that pretreatment with a low dose of PDT significantly sensitizes bladder cancer cells to TRAIL-induced apoptosis. Chlorin-based PDT augments the effect of TRAIL on bladder cancer cells. Conclusions PDT with Ce6-PVP photosensitizer enhances the cytotoxic and apoptotic effects of TRAIL on bladder cancer cells. The obtained results suggest that combined treatment by TRAIL and PDT may provide the basis for a new therapeutic approach to induce cell death in bladder cancer.

ALA-induced photodynamic effect on vitality, apoptosis, and secretion of vascular endothelial growth factor (VEGF) by colon cancer cells in normoxic environment in vitro

BACKGROUNDnCancer therapy is often based on combination of conventional methods of cancer treatment with immunotherapy. Photodynamic therapy (PDT) is one of the immunomodulating methods used in oncology. We examined how PDT influences the secretory activity of colon cancer cells in vitro, especially the secretion of vascular endothelial growth factor (VEGF) in aerobic conditions.nnnMETHODSnWe used two cancer cell lines with different malignancy potentials: a metastatic SW620 line and a non-metastatic SW480 line. In the first stage of the experiment, we exposed each cell line to three different concentrations of photosensitizers precursor: 5-aminolevulinic acid (ALA) and varying levels of light radiation, after which we assessed cell viability and apoptosis induction in these lines, using the MTT and LDH assays. Then, we determined the secretion of VEGF by these cells in aerobic conditions and under the ALA-PDT parameters at which cells presented the highest viability.nnnRESULTSnPhotodynamic treatment with ALA did not influence on VEGF secretion by the non-metastatic SW480 cells, but caused a decrease in VEGF secretion by the metastatic SW 620 cell line by 29% (p<0.05). SW 620 cell line secreted more actively VEGF than the SW480 cells, both before and after photo dynamic therapy (p<0.05).nnnCONCLUSIONnThe outcome of this in vitro study presented a beneficial effect of ALA-PDT, resulting in a decrease of VEGF secretion in the more malignant SW620 cell lines. Further studies should be considered to confirm the clinical relevance of this finding.

The etiology of lower respiratory tract infections in people with diabetes

Patients with diabetes mellitus (DM) are likely to develop many types of infections, which affect the transport of glucose into tissues. Diabetes increases the susceptibility to different kinds of respiratory infections, is often identified as an independent risk factor for developing lower respiratory tract infections. Pulmonary infections caused by Mycobacterium tuberculosis, Staphylococcus aureus, gram-negative bacteria and fungi may occur with an increased frequency, whereas infections due to Streptococcus pneumonia or influenza virus may be associated with increased morbidity and mortality. During lung infection, there are changes in the local and ciliary epithelial lining. Increased susceptibility to pneumococcal infection by people with diabetes is the result of reduced defense capability of antibodies to protein antigens. The relationship between diabetes and pulmonary tuberculosis is well known, and the incidence of tuberculosis in diabetic individuals is 4-5 times greater than among the non-diabetic population. It is thought that malfunction of monocytes in patients with diabetes may contribute to the increased susceptibility to tuberculosis and/or a worse prognosis. Hospitalization of patients with diabetes due to influenza virus or flu-like infections is up to 6 times more likely to occur compared to healthy individuals, also diabetic patients are more likely to be hospitalized due to infection complications. Immunization with influenza and anti-pneumococcal vaccines is recommended to reduce hospitalizations, deaths, and medical expenses. Diabetes, especially the uncontrolled one, predisposes to fungal infection, the most common candidiasis and mucormycosis.

Anti-Candida Activity of 4-Morpholino-5-Nitro- and 4,5-Dinitro-Imidazole Derivatives

The activities of some 4-morpholino-5-nitro- and 4,5-dinitro-imidazole derivatives with respect to several Candida species were evaluated. It is established that 4,5-dinitroimidazole derivatives constitute an important group of compounds possessing antifungal activity against Candida species. Some analogs showed moderate antifungal ability in vitro, especially in relation well-known antifungals such as flucytosine (5FC). The best results of antifungal action were obtained for 1-(3-bromo-2-hydroxypropyl)-2-methyl-4,5-dinitroimidazole (3c), 1-(3-bromo-2-oxopropyl)-2-methyl-4,5-dinitroimidazole (4c) and 2-methyl-1-phenacyl-4,5-dinitroimidazole (2b). The latter compound proved to be effective against Candida sake S-1 (in contrast to inactive 5FC).