Microendoscopy for hypericin fluorescence tumor diagnosis in a subcutaneous glioma mouse model

Synergistic effect of folic acid and hypericin administration to improve the efficacy of photodynamic therapy via folate receptors

Transport systems are developed to improve the solubility of the transported drug, increase its stability, enhance its pharmacological activity and target cancer while minimising side effects. In this work, nanoporous silica particles that can be functionalized and loaded with a large number of hydrophobic molecules are proposed. The designed system was modified with folic acid to target the folic acid receptors of cancer cells. This modification enabled a higher uptake of the drug by the cells. Hypericin was selected as a hydrophobic molecule/drug with photodynamic properties suitable for diagnosis and therapy. Fluorescence microscopy and flow cytometry were used to detect the targeting and distribution of hypericin in the cancer cells. Furthermore, the combination of folic acid and hypericin has been shown to form singlet oxygen and to have a synergistic effect in improving the efficacy of photodynamic therapy. The functionalisation of the particles proposed in this work holds great potential for the delivery of hydrophobic drugs to other types of cancer cells with increased expression of the folic acid receptor to which the particles can be attached.

Hypericin: A natural anthraquinone as promising therapeutic agent

BACKGROUND

Hypericin is a prominent secondary metabolite mainly existing in genus Hypericum. It has become a research focus for a quiet long time owing to its extensively pharmacological activities especially the anti-cancer, anti-bacterial, anti-viral and neuroprotective effects. This review concentrated on summarizing and analyzing the existing studies of hypericin in a comprehensive perspective.

METHODS

The literature with desired information about hypericin published after 2010 was gained from electronic databases including PubMed, SciFinder, Science Direct, Web of Science, China National Knowledge Infrastructure databases and Wan Fang DATA.

RESULTS

According to extensive preclinical and clinical studies conducted on the hypericin, an organized and comprehensive summary of the natural and artificial sources, strategies for improving the bioactivities, pharmacological activities, drug combination of hypericin was presented to explore the future therapeutic potential of this active compound.

CONCLUSIONS

Overall, this review offered a theoretical guidance for the follow-up research of hypericin. However, the pharmacological mechanisms, pharmacokinetics and structure activity relationship of hypericin should be further studied in future research.

Photophysical characterization of Hypericin-loaded in micellar, liposomal and copolymer-lipid nanostructures based F127 and DPPC liposomes

Hypericin (Hy) compound presents a high photoactivity in photodynamic therapy (PDT), photodiagnosis and theranostics applications. The maintenance of this compound in monomeric form could undermine the potential benefits of its photophysical and photodynamic activity. In this study, we demonstrated that the Hy formulated in a system based on the use of the F127 copolymer and the 1,2-dipalmitoyl-sn-3-glycerol-phosphatidylcholine (DPPC) as micelles, liposomal vesicles and Copolymer-Lipid coated systems, have improved its photophysical properties for many clinical modalities. Based on the results of the triplet state lifetime values (τ_t), the singlet oxygen quantum yield (Φ_Δ¹O₂), the fluorescence lifetime (τ_F) and the fluorescence quantum yield (Φ_F), all Hy formulations had its photophysical properties described in different models of drug delivery systems (DDS). In addition, the transient spectra profile of those formulations was unaffected by the Hy incorporation process, except for the liposomal system, which demonstrated to be the less stable one by flash photolysis technique. The cytotoxic effects of those formulations were also investigated for CaCo-2 and HaCat cells line. The cytotoxic concentrations for 50% (CC₅₀) were 0.56, 1.05, 1.33 and 4.80 µmol L^-1 for Copolymer-Lipid/Hy, DPPC/Hy, F127/Hy and ethanol/Hy for CaCo-2 cells, respectively, and 0.69, 2.02, 1.45 and 1.16 µmol L^-1 for Copolymer-Lipid/Hy, DPPC/Hy, F127/Hy and ethanol/Hy for HaCat cells, respectively. The F127 copolymer had a significant role in many photophysical parameters determined for Copolymer-Lipid/Hy coated system. Although all those formulations had shown satisfactory results, Copolymer-Lipid/Hy proved to be superior in many aspects, being the most promising formulation for PDT, photodiagnosis and theranostics applications.

Antibody-Based Immunotherapy: Alternative Approaches for the Treatment of Metastatic Melanoma

Melanoma is the least common form of skin cancer and is associated with the highest mortality. Where melanoma is mostly unresponsive to conventional therapies (e.g., chemotherapy), BRAF inhibitor treatment has shown improved therapeutic outcomes. Photodynamic therapy (PDT) relies on a light-activated compound to produce death-inducing amounts of reactive oxygen species (ROS). Their capacity to selectively accumulate in tumor cells has been confirmed in melanoma treatment with some encouraging results. However, this treatment approach has not reached clinical fruition for melanoma due to major limitations associated with the development of resistance and subsequent side effects. These adverse effects might be bypassed by immunotherapy in the form of antibody–drug conjugates (ADCs) relying on the ability of monoclonal antibodies (mAbs) to target specific tumor-associated antigens (TAAs) and to be used as carriers to specifically deliver cytotoxic warheads into corresponding tumor cells. Of late, the continued refinement of ADC therapeutic efficacy has given rise to photoimmunotherapy (PIT) (a light-sensitive compound conjugated to mAbs), which by virtue of requiring light activation only exerts its toxic effect on light-irradiated cells. As such, this review aims to highlight the potential clinical benefits of various armed antibody-based immunotherapies, including PDT, as alternative approaches for the treatment of metastatic melanoma.

Hypericin photodynamic activity in DPPC liposome. PART I: biomimetism of loading, location, interactions and thermodynamic properties

Hypericin (Hyp) is a potential photosensitizer drug for Photodynamic Therapy (PDT). However, the high lipophilicity of Hyp prevents its preparation in water. To overcome the Hyp solubility problem, this study uses the liposomal vesicle of DPPC. Otherwise liposome is also one of the most employed artificial systems that mimetizes cell membranes. Our present focus is the interaction of Hyp into DPPC liposome as biomimetic system. We studied the loading, interaction, and localization of Hyp (2.8 μmol L^-1) in DPPC (5.4 mmol L^-1) liposomes, as well as the thermodynamic aspects of Hyp-liposomes. The Hyp addition to the DPPC liposome dispersion showed a Encapsulation Efficiency for [Hyp] = 2.8 μmol L^-1 in [DPPC] = 5.3 mmol L^-1 of 74.3% and 89.3% at 30.0 and 50.0 °C, respectively. The encapsulation profile obeys a pseudo first-order kinetic law, with a rate constant of 1.26 × 10^-3 s^-1 at 30.0 °C. Also the data suggests this reaction is preceded by an extremely rapid step. A study on the binding of Hyp/DPPC liposomes (K_b), performed at several temperatures, showed results of 4.8 and 18.5 × 10³ L mol^-1 at 293 and 323 K, respectively. Additionally, a decrease was observed in the ΔG of the Hyp/DPPC interaction (-20.6 and - 26.4 kL mol^-1 at 293 and 323 K, respectively). The resulting ΔH > 0 with ΔS < 0 shows that the entropy is driven the process. Studies of Hyp location in the liposome at 298 K revealed the existence of two different Hyp populations with a Stern-Volmer constant (K_sv) of 4.65 and 1.87 L mol^-1 using iodide as an aquo-suppressor at concentration ranged from 0 to 0.025 mol L^-1 and from 0.025 to 0.150 mol L^-1, respectively. Furthermore, studies of Fluorescence Resonance Energy Transfer, using DPH as a donor and Hyp as an acceptor, revealed that Hyp is allocated in different binding sites of the liposome. This is dependent on temperature. Thermal studies revealed that the Hyp/DPPC formulation presented reasonable stability. Size and morphological investigations showed that Hyp incorporation increases the average size of DPPC liposomes from 116 to 154 nm. The study demonstrated the ability of the Hyp-DPPC liposome as an interesting system for drug delivery system that can be applied to PDT.

Hypericin in the Light and in the Dark: Two Sides of the Same Coin

Hypericin (4,5,7,4',5',7'-hexahydroxy-2,2'-dimethylnaphtodianthrone) is a naturally occurring chromophore found in some species of the genus Hypericum, especially Hypericum perforatum L. (St. John's wort), and in some basidiomycetes (Dermocybe spp.) or endophytic fungi (Thielavia subthermophila). In recent decades, hypericin has been intensively studied for its broad pharmacological spectrum. Among its antidepressant and light-dependent antiviral actions, hypericin is a powerful natural photosensitizer that is applicable in the photodynamic therapy (PDT) of various oncological diseases. As the accumulation of hypericin is significantly higher in neoplastic tissue than in normal tissue, it can be used in photodynamic diagnosis (PDD) as an effective fluorescence marker for tumor detection and visualization. In addition, light-activated hypericin acts as a strong pro-oxidant agent with antineoplastic and antiangiogenic properties, since it effectively induces the apoptosis, necrosis or autophagy of cancer cells. Moreover, a strong affinity of hypericin for necrotic tissue was discovered. Thus, hypericin and its radiolabeled derivatives have been recently investigated as potential biomarkers for the non-invasive targeting of tissue necrosis in numerous disorders, including solid tumors. On the other hand, several light-independent actions of hypericin have also been described, even though its effects in the dark have not been studied as intensively as those of photoactivated hypericin. Various experimental studies have revealed no cytotoxicity of hypericin in the dark; however, it can serve as a potential antimetastatic and antiangiogenic agent. On the contrary, hypericin can induce the expression of some ABC transporters, which are often associated with the multidrug resistance (MDR) of cancer cells. Moreover, the hypericin-mediated attenuation of the cytotoxicity of some chemotherapeutics was revealed. Therefore, hypericin might represent another St. John's wort metabolite that is potentially responsible for negative herb-drug interactions. The main aim of this review is to summarize the benefits of photoactivated and non-activated hypericin, mainly in preclinical and clinical applications, and to uncover the "dark side" of this secondary metabolite, focusing on MDR mechanisms.

Neurotensin signaling stimulates glioblastoma cell proliferation by upregulating c-Myc and inhibiting miR-29b-1 and miR-129-3p

BACKGROUND

Neurotensin (NTS) and its primary receptor NTSR1 are implicated in cancer progression. Aberrant expression of NTS/NTSR1 contributes to the proliferation of glioblastoma cells; however, the mechanism is not fully understood.

METHODS

Microarray and real-time PCR were performed to identify the NTS-regulated micro (mi)RNAs. The targets of the miRNAs were identified by luciferase assays and immunoblot analysis. The c-Myc binding sites in the miR-29b-1 and cyclin-dependent kinase (CDK)4 promoters were identified through chromatin immunoprecipitation assay. Cell proliferation was evaluated by Cell Counting Kit-8 assay and flow cytometry analysis. An orthotopic xenograft model demonstrated the role of NTS/NTSR1 and miRNAs in glioblastoma growth in vivo.

RESULTS

Pharmacological inhibition or small interfering NTSR1 treatment blocked glioblastoma cell cycle progression in the G1 phase with a concomitantly decreased expression of CDK6, CDK4, and c-Myc. Knockdown of NTSR1 increased the expression of miR-29b-1 and miR-129-3p, which were responsible for the decreased CDK6 expression. NTS/NTSR1 signaling activated the transcription factor c-Myc in U87 cells, leading to increased CDK4 expression and repressed miR-29b-1 expression. Knockdown of NTSR1 decreased the glioblastoma growth in vivo and significantly prolonged the survival time of the tumor-bearing mice, an effect that can be largely reversed by antagomir.

CONCLUSIONS

Our study showed a novel regulatory mechanism of NTS/NTSR1, an upstream signaling of miRNAs and c-Myc, in glioblastoma progression. The inhibition of the NTSR1 function or the upregulation of miR-29b-1 and miR-129-3p expression impaired glioma cell proliferation. These results suggested that the NTS/NTSR1/c-Myc/miRNA axis may be a potential therapeutic target for glioblastoma therapy.