Hypericin photosensitization of tumor and metastatic cell lines of human prostate

Cross-Kingdom Gene regulation via miRNAs of Hypericum perforatum (St. John's wort) flower dietetically absorbed: An in silico approach to define potential biomarkers for prostate cancer

Prostate cancer (PCa) is the most frequent type of cancer in men. Hypericum perforatum (H. Perforatum) extract (HPE) administration provides remarkable decrease of PCa development. H. perforatum contains 7 conserved miRNAs (Hyp-miR-156a, Hyp-miR-156b, Hyp-miR-166, Hyp-miR-390, Hyp-miR-394, Hyp-miR-396 and Hyp-miR-414) with different targets. In this study, we aimed to investigate cross-kingdom gene regulation via miRNAs of H. perforatum flower dietetically absorbed in manner of an in silico approach to define potential biomarkers for PCa. psRNATarget database was used to find human genes targeted by 7 pre-defined H. perforatum miRNAs. We defined the mostly affected gene families from these miRNAs as ZNF, TMEM, SLC and FAM gene families. GeneMANIA database was used to define the most affected genes (TMEM41B and SLC4A7) from these 7 miRNAs. cBioPortal database was used to define alteration frequencies of TMEM41B and SLC4A7 on different types of PCa and to measure the mutual interaction potency and significance of co-occurence in PCa. This analysis showed that neuroendocrine prostate cancer (NEPC) had the highest total mutation frequency (22%) of TMEM41B and SLC4A7 genes. Also, TMEM41B and SLC4A7 genes had an average 2.1% pathway change potential among all different types of PCa. Moreover, TMEM41B and SLC4A7 gene pair was found significantly co-occurrent in PCa (p < 0.001). Finally, via GEPIA database, we used Spearman correlation analysis to measure the correlation degree of TMEM41B and SLC4A7 genes in PCa and found their significant correlation with PCa (p = 1.2 × 10^-12, R = 0.28). All in all, it was proved in silico and supported with previously known clinical data that SLC4A7 and TMEM41B potentially have a significant and critical tumor suppressive role for PCa, and show this effect combinatorily working together. This is the first study correlating SLC4A7 and TMEM41B with PCa significantly.

Effects of Hypericum perforatum extract and its main bioactive compounds on the cytotoxicity and expression of CYP1A2 and CYP2D6 in hepatic cells

AIMS

Hypericum perforatum (H. perforatum) is one of the most used medicinal plants. However, it has been associated with relevant interactions with several drugs. This situation is probably mediated by cytochrome P450 enzymes (CYP450), namely the 1A2 (CYP1A2) and 2D6 (CYP2D6) isoforms This study aims to assess the cytotoxic and CYP1A2 and CYP2D6 inductive and/or inhibitory effects of a H. perforatum extract and its main bioactive components in hepatic cell lines.

MAIN METHODS

A MTT proliferation assay was performed in WRL-68, HepG2 and HepaRG cells after exposition to different concentrations of H. perforatum extract, hypericin and hyperforin for 24 and 72 h. Then, a real-time PCR analysis was accomplished after incubating the cells with these products evaluating the relative CYP1A2 and CYP2D6 expression.

KEY FINDINGS

These products have relevant cytotoxicity at a 10 μM concentration and it was also demonstrated for the first time that H. perforatum can lead to a significant CYP1A2 and CYP2D6 induction in all cell lines. Moreover, hypericin seems to induce CYP1A2 in HepG2 cells and to inhibit its expression in HepaRG cells while hyperforin induced CYP1A2 in HepG2 and in WRL-68 cells. Additionally, hypericin and hyperforin induce CYP2D6 in HepG2 cells but inhibits its expression in HepaRG and in WRL-68 cells.

SIGNIFICANCE

This study not only evidenced that H. perforatum extract and two of its bioactive components can have toxic effects in hepatic cell lines but also emphasized the potential risk of the consumption of H. perforatum with CYP1A2- and CYP2D6-metabolized drugs.

Photodynamic therapy in urology: what can we do now and where are we heading?

BACKGROUND

Photodynamic therapy (PDT) is an innovative technique in oncologic urology. Its application appears increasingly realistic to all kind of cancers with technological progress made in treatment planning and light delivery associated with the emergence of novel photosensitizers. The aim of this study is to review applications of this technique in urology.

MATERIALS AND METHODS

We reviewed the literature on PDT for urological malignancies with the following key words: photodynamic therapy, prostate cancer, kidney cancer, urothelial cancer, penile cancer and then by cross-referencing from previously identified studies.

RESULTS

Focal therapy of prostate cancer is an application of PDT. Clinical studies are ongoing to determine PDT efficacy and safety. PDT as salvage treatment after radiotherapy has been tested. Oncologic results were promising but important side effects were reported. Individual dosimetric planning is necessary to avoid toxicity. PDT was tested to treat superficial bladder carcinoma with promising oncologic results. Serious side effects have limited use of first photosensitizers generation. Second generation of photosensitizer allowed reducing morbidity. For upper urinary tract carcinoma and urethra, data are limited. Few studies described PDT application in penile oncology for conservative management of carcinoma in situ and premalignant lesions. For renal cancer, PDT was only tested on preclinical model despite of its potential application. No data is available concerning PDT application for testicular cancer.

CONCLUSION

PDT clinical applications in urology have proved a kind of efficiency balanced with an important morbidity. Development of new photosensitizer generations and improvement in illumination protocols should permit to decrease side effects.

Inhibition characteristics of hypericin on rat small intestine glutathione-S-transferases

Glutathione-S-transferases constitute a family of enzymes involving in the detoxification of xenobiotics, signalling cascades and serving as ligandins or/and catalyzing the conjugation of various chemicals and drugs. The widely expressed cytosolic GST-pi is a marker protein in various cancers and its increased concentration is linked to drug resistance. GST-pi is autoregulated by S-glutathionylation and it catalyzes the S-glutathionylation of other proteins in response to oxidative or nitrosative stress. S-glutathionylation of GST-pi results in multimer formation and the breakage of ligand binding interactions with c-Jun NH(2)-terminal kinase (JNK). Another widely expressed GST enzyme, GST-alpha is assumed as a marker in hepatocellular damage, is implicated in cancer, asthma, cardiovascular disease and response to chemotherapy. Although, it was shown that hypericin binds and inhibits GST-alpha and GST-pi, the inhibition characteristics have not been investigated in detail. The aim of this study was to investigate the effects of hypericin on major GSTs; GST-alpha and GST-pi purified from rat small intestine. When GSH used as varied substrate the inhibition pattern with hypericin was uncompetitive for GST-alpha (K(i)=0.16 + or - 0.02 microM) and noncompetitive for GST-pi (K(i) = 2.46 + or - 0.43 microM). While using CDNB (1-chloro-2,4-dinitrobenzene) as the varied substrate, the inhibition patterns were noncompetitive for GST-alpha and competitive for GST-pi; K(i) values for GST-alpha and GST-pi were 1.91 + or - 0.21 and 0.55 + or - 0.07 microM, respectively. Since hypericin accumulated in cancer cells and important in photodynamic therapy (PDT), inhibition of GST-alpha and GST-pi by hypericin might increase the effectivity of the treatment. Considering that GST-pi is responsible for the drug resistance its inhibition might increase the benefit obtained from chemotherapy.

Photodynamic effect of hypericin in primary cultures of human umbilical endothelial cells and glioma cell lines

Hypericin is the most powerful naturally occurring photosensitizer and as such there is renaissant interest in the potentials of this compound for anticancer photodynamic therapy (PDT). The purpose of this study was to investigate the hypericin-mediated photodynamic therapy effects on normal human umbilical endothelial cells (HUVECs) in comparison with cancer human glioma cell lines U-87 MG and U-373 MG, in in vitro conditions. The data suggest that endothelial cells as well as glioma cell lines are sensitive only to photoactivated hypericin. The inhibitory effects of photoactivated hypericin did not differ in endothelial compared with tumor cells in cytotoxicity MTT and DNA fragmentation assays. However, an important difference in sensitivity was found between the above mentioned cell types in migration and metalloproteinases inhibition assays performed as cell function tests. The findings in both function tests were supported by the high sensitivity of endothelial cells in an additional angiogenesis test of tubular formation in vitro.

Hypericin-induced photocytotoxicity is connected with G2/M arrest in HT-29 and S-phase arrest in U937 cells

Susceptibility of the HT-29 human colon adenocarcinoma cell line and human myeloid leukemia cell line U937 to hypericin-mediated photocytotoxicity was investigated and compared in this study. Cellular parameters as viability, cell number, metabolic activity and total protein amount were monitored in screening experiments with subsequent cell-cycle analysis and apoptosis detection to determine the cellular response of the different tumor types to various concentrations of photoactivated hypericin. The results show concentration dependence of the photosensitizer's cytotoxicity on the studied cell lines, with higher sensitivity of U937 cells. Whereas the two extreme hypericin concentrations (1 x 10(-9) M and 1 x 10(-6) M) resulted in similar changes in all tested cellular parameters on the two studied cell lines, 1 x 10(-8) M and 1 x 10(-7) M hypericin treatment resulted in different responses of the cell lines in all monitored parameters except for viability. Although leukemic cells proved sensitive to both 1 x 10(-8) M and 1 x 10(-7) M hypericin, significant changes on HT-29 cells were detected only after the 1 x 10(-7) M hypericin concentration. Cell-cycle arrest was related to simultaneously occurring apoptosis in colon cancer. Remarkable is the difference in cell-cycle profile where G2/M arrest in colon cancer cells versus accumulation of leukemic cells in the S phase appears. This suggests that hypericin treatment affecting the cell-cycle machinery of different cancer cells is not universal in effect.

A melatonin-rich germplasm line of St John's wort (Hypericum perforatum L.)

The objective of this study was to evaluate the possibility of selecting genetic variants of plants with enhanced concentrations of the indoleamine melatonin. A germplasm line of the medicinal plant species, St John's wort (Hypericum perforatum L.), with high levels of melatonin was selected in vitro using mutagenized tissues. The germplasm line has remained stable over a 5-yr period and contained >12-fold (1200%) melatonin content compared with the wild-type plant. Melatonin is a ubiquitous, highly conserved molecule with known therapeutic roles in the treatment of sleep disorders, depression, aging, inhibition of cancer cell growth and as a free radical scavenger and antioxidant. The selected melatonin-rich germplasm line of St John's wort may facilitate fundamental studies on melatonin biosynthesis, metabolism and new developments in natural products for treatment of human diseases.

Does Hypericum perforatum L. extract show any specificity as photosensitizer for HL-60 leukemic cells and cord blood hemopoietic progenitors during photodynamic therapy?

Autologous bone marrow transplantation is a therapeutic modality that increases the survival rates for children with malignancies with poor prognosis but relapse rates are high and attributed partially to the existence of residual malignant cells. Photodynamic treatment (PDT) has been developed among purging strategies. We investigated the effect of the methanolic extract (ME) and its polar methanolic fraction (PMF) of Hypericum perforatum L., as a new photosensitizer for the leukemic cell line HL-60 and cord blood (CB) hemopoietic progenitors as well as the subcellular localization of the photosensitizer.

METHODS

ME and PMF were prepared after extraction of the dry herb with methanol (ME), followed by liquid-liquid extraction with petroleum ether (PMF). Cells were incubated with the extracts before irradiation with Nd-Yvo Laser. Various concentrations of PMF or ME as well as irradiation doses were tested. Following irradiation, cell viability was determined by trypan blue in continuous liquid cultures for HL-60 cells and in clonogenic assays for CB cells. The subcellular localization of the photosensitizer was determined by confocal microscopy.

RESULTS

Laser photoirradiation in the presence of both PMF and ME induces the killing of HL-60 cells. This effect is dose dependent. No CFU-GM and BFU-E growth was observed from CB mononuclear cells under the tested experimental conditions. Confocal microscopy revealed that the extracts localize mainly in the cytoplasm of the cells.

CONCLUSIONS

PDT with both PMF and ME induces the killing of HL-60 leukemic cells and the optimal conditions of treatment were determined. This effect of PDT/PMF was also exerted on CB progenitor cells indicative of the non-selective uptake of the photosensitizer by malignant cells. Though this suggests that PDT/PMF cannot be helpful in autologous bone marrow purging, these novel extracts can however be beneficial in the PDT treatment of tumors given their photostability, low toxicity and low cost.

Photodynamic therapy: a new approach to prostate cancer

Photodynamic therapy (PDT) is based on the concept that light irradiation can change an inert substance into an active one. In urology, hematoporphyrin derivative (HpD) and Photofrin (Axcan Scandipharm Inc., Birmingham, AL) are used most commonly as photosensitizing agents predominantly for the treatment of transitional cell carcinoma of the bladder. To investigate the basics for PDT of prostate cancer, several studies were performed on the optical characteristics of prostate tissue and prostate carcinoma tissue in vitro and in vivo and on the penetration depths of different laser wavelengths. Initial experimental studies to treat prostate cancer with PDT using HpD were done on Dunning tumors in rats. Combined with interstitial applicators, photodynamic therapy seems to have a great potential in the treatment of prostate carcinoma. However, it is an experimental treatment and even a preliminary evaluation will be possible only after the conclusion of clinical studies with the corresponding long-term results.

Chemical and photochemical electron transfer of new helianthrone derivatives: aspects of their photodynamic activity

Helianthrones 2-4 are a new class of synthetic photosensitizers, which have a molecular skeleton related to that of hypericin. We established that irradiation of heliantrones with visible light leads to the formation of semiquinone radicals and reactive oxygen species. The structures of the paramagnetic anion species produced by electron transfer were calculated on the density functional level and investigated by cyclovoltammetry, UV/vis, and EPR/ENDOR spectroscopy. As with hypericin, the pi system of the helianthrones was found to be considerably deviated from planarity, and, upon electron transfer, deprotonation in the bay region occurs. The structure of the semiquinone radicals was found to be identical in THF, DMF, and aqueous buffered solutions regardless of the means by which reduction was achieved. Semiquinone radicals can be formed via self-electron transfer between the excited state and the ground state or via electron transfer from an electron donor to the excited state of helianthrone. Therefore, the presence of an electron donor significantly enhanced the photogeneration of semiquinone and superoxide radical. The kinetic studies showed that no significant photochemical destruction of helianthrones occurred upon irradiation. Generation of superoxide and singlet oxygen upon irradiation of helianthrones was established by spin trapping techniques. This shows that both type I and type II mechanisms are of importance for the photodynamic action of these compounds.

Preclinical studies in normal canine prostate of a novel palladium-bacteriopheophorbide (WST09) photosensitizer for photodynamic therapy of prostate cancers

Photodynamic therapy (PDT) uses light to activate a photosensitizer to achieve localized tumor control. In this study, PDT mediated by a second-generation photosensitizer, palladium-bacteriopheophorbide WST09 (Tookad) was investigated as an alternative therapy for prostate cancer. Normal canine prostate was used as the animal model. PDT was performed by irradiating the surgically exposed prostate superficially or interstitially at 763 nm to different total fluences (100 or 200 J/cm2; 50, 100 or 200 J/cm) at 5 or 15 min after intravenous administration of the drug (2 mg/kg). Areas on the bladder and colon were also irradiated. The local light fluence rate and temperature were monitored by interstitial probes in the prostate. All animals recovered well, without urethral complications. During the 1 week to 3 month post-treatment period, the prostates were harvested for histopathological examination. The PDT-induced lesions showed uniform hemorrhagic necrosis and atrophy, were well delineated from the adjacent normal tissue and increased linearly in diameter with the logarithm of the delivered light fluence. A maximum PDT-induced lesion size of over 3 cm diameter could be achieved with a single interstitial treatment. There was no damage to the bladder or rectum caused by scattered light from the prostate. The bladder and rectum were also directly irradiated with PDT. At 80 J/cm2, a full-depth necrosis was observed but resulted in no perforation. At 40 J/cm2, PDT produced minimal damage to the bladder or rectum. On the basis of optical dosimetry, we have estimated that 20 J/cm2 is the fluence required to produce prostatic necrosis. Thus, the normal structure adjacent to the prostate can be safely preserved with careful dosimetry. At therapeutic PDT levels, there was no structural or functional urethral damage even when the urethra was within the treated region. Hence, Tookad-PDT appears to be a promising candidate for prostate ablation in patients with recurrent, or possibly even primary, prostate cancer.

Hypericin in cancer treatment: more light on the way

Photodynamic therapy (PDT) has been described as a promising new modality for the treatment of cancer. PDT involves the combination of a photosensitizing agent (photosensitizer), which is preferentially taken up and retained by tumor cells, and visible light of a wavelength matching the absorption spectrum of the drug. Each of these factors is harmless by itself, but when combined they ultimately produce, in the presence of oxygen, cytotoxic products that cause irreversible cellular damage and tumor destruction. Hypericin, a powerful naturally occurring photosensitizer, is found in Hypericum perforatum plants, commonly known as St. John's wort. In recent years increased interest in hypericin as a potential clinical anticancer agent has arisen since several studies established its powerful in vivo and in vitro antineoplastic activity upon irradiation. Investigations of the molecular mechanisms underlying hypericin photocytotoxicity in cancer cells have revealed that this photosensitizer can induce both apoptosis and necrosis in a concentration and light dose-dependent fashion. Moreover, PDT with hypericin results in the activation of multiple pathways that can either promote or counteract the cell death program. This review focuses on the more recent advances in the use of hypericin as a photodynamic agent and discusses the current knowledge on the signaling pathways underlying its photocytotoxic action.

St John's wort (Hypericum perforatum L.): a review of its chemistry, pharmacology and clinical properties

The chemical composition of St. John's wort has been well-studied. Documented pharmacological activities, including antidepressant, antiviral, and antibacterial effects, provide supporting evidence for several of the traditional uses stated for St John's wort. Many pharmacological activities appear to be attributable to hypericin and to the flavonoid constituents; hypericin is also reported to be responsible for the photosensitive reactions that have been documented for St. John's wort. With regard to the antidepressant effects of St John's wort, hyperforin, rather than hypericin as originally thought, has emerged as one of the major constituents responsible for antidepressant activity. Further research is required to determine which other constituents contribute to the antidepressant effect. Evidence from randomised controlled trials has confirmed the efficacy of St John's wort extracts over placebo in the treatment of mild-to-moderately severe depression. Other randomised controlled studies have provided some evidence that St John's wort extracts are as effective as some standard antidepressants in mild-to-moderate depression. There is still a need for further trials to assess the efficacy of St John's wort extracts, compared with that of standard antidepressants, particularly newer antidepressant agents, such as the selective serotonin reuptake inhibitors (recent comparative studies with fluoxetine and sertraline have been conducted). Also, there is a need for further studies in well-defined groups of patients, in different types of depression, and conducted over longer periods in order to determine long-term safety. St John's wort does appear to have a more favourable short-term safety profile than do standard antidepressants, a factor that is likely to be important in patients continuing to take medication. Concerns have been raised over interactions between St John's wort and certain prescribed medicines (including warfarin, ciclosporin, theophylline, digoxin, HIV protease inhibitors, anticonvulsants, selective serotonin reuptake inhibitors, triptans, oral contraceptives); advice is that patients taking these medicines should stop taking St John's wort, generally after seeking professional advice as dose adjustment of conventional treatment may be necessary.

Tumor-specific and photodependent cytotoxicity of hypericin in the human LNCaP prostate tumor model

Hypericin (HYP) has been reported to have photodependent cytotoxic activity in a variety of cancer cell lines. However, this activity has yet to be rigorously tested in vivo in tumor models. In this study LNCaP, PC-3 and DU-145 cells were used to test the cytotoxic effects of HYP in vitro, precursory to an in vivo study designed to investigate the effects of HYP in an established murine model for prostate cancer. Specifically, the model used employs immunocompromised nude mice bearing the LNCaP solid tumor xenograft. In vitro cytotoxicity experiments indicated that the dose causing 50% lethality for HYP in LNCaP, PC-3 and DU-145 cells were 2.07, 2.15 and 2.23 microM, respectively, following irradiation with red light (590 nm) for 30 min at a fluence rate of 0.1 J/cm2/s. Cells treated with HYP in the absence of photoirradiation showed no signs of cytotoxicity. A tissue distribution study was also carried out using the LNCaP solid tumor model to determine whether or not HYP is distributed to the target tissue. HYP was broadly distributed in tissues studied, including LNCaP tumor xenograft tissue. Furthermore, tumor tissue eliminated HYP at a slower rate than any of the other tissues examined. Interestingly, HYP levels were maintained in serum 24 h after oral administration (5 mg/kg dose). A pilot study designed to examine the efficacy of HYP treatment in nude mice bearing LNCaP tumors conducted over 28 days suggested that HYP, in combination with photoirradiation, inhibits both tumor growth and the elevation of prostate-specific antigen levels. Although the results reported for the current studies are preliminary they do provide evidence for an application of HYP PDT to prostate cancer which warrants further investigation.

Spectroscopic study of visible-light effects on hypericin-lens proteins systems

Molecular interactions between hypericin and alpha-, beta- and gamma-crystallin proteins have been studied by means of absorption and steady-state fluorescence spectroscopy, aiming to clarify if and how the pigment binds to the proteins and to investigate the effects of visible-light irradiation on these molecular systems. Such a study is a prerequisite for assessing the possibility of using hypericin as a mild antidepressant and/or as a photodynamic agent for the treatment of eye tumors and eye viral and bacterial diseases without side injuries to the lens. We have shown that in dark-kept samples, with increasing alpha-crystallin concentration, both the fluorescence emission intensity and the ratio of the absorption maxima around 590 and 550 nm of hypericin increase. These effects have been attributed to the monomerization of nonfluorescent hypericin aggregates caused by the binding of the pigment to alpha-crystallin. The binding constant of hypericin has been evaluated to be of the order of 3.0 (mg/mL)-1, corresponding to a dissociation constant of the order of 0.3 mg/mL. Following irradiation with light of wavelengths over 400 nm, at an irradiance of 20 mW/cm2, both tryptophan and hypericin fluorescence emission intensities decrease. These effects are suggested to be the consequence of a spatial rearrangement of the protein framework which takes place following the alpha-crystallin photopolymerization sensitized by hypericin itself described in the literature. For the sake of comparison hypericin has been studied also in the presence of beta H-, beta L- and gamma-crystallins at the same concentration.