Photodynamic therapy for cancer: Role of natural products

Effect of photodynamic therapy on expression of HRAS, NRAS and caspase 3 genes at mRNA levels, apoptosis of head and neck squamous cell carcinoma cell line

OBJECTIVES

This study aimed to assess the effect of photodynamic therapy (PDT) on expression of CASP3, NRAS and HRAS genes at mRNA levels, and apoptosis of head and neck squamous cell carcinoma (HNSCC) cell line.

MATERIALS AND METHODS

In order to complete the present in vitro study, HNSCC cell line (NCBI C196 HN5) purchased from Pasteur Institute. Cells were divided into four groups; Group 1: photodynamic treatment (laser + methylene blue (MB) as photosensitizer), group 2: MB, group 3: laser (with 660 nm wavelength), and group 4: control (without any treatment). To determine the optimal concentration of MB, in a pilot study, toxicity of MB in different concentration was assessed using MTT assay. Cells in group 1, 2 and 3 was treated at optimal concentration of MB (1.6 μg/mL). Gene expression at mRNA levels was assessed after 24 h incubation, using real-time (qRT)-PCR. The expression of BAX and BCL2 genes at the mRNA levels was analyzed to evaluate apoptosis. 2^-ΔΔCt values of BCL2, BAX, CASP3, NRAS, and HRAS in groups was analyzed using ANOVA. Tukey's HSD and Games Howell test was used to compare between two groups.

RESULTS

Over-expression of BAX (p < 0.001), CASP3 (p < 0.001) and down-regulation of BCL2 (p = 0.004), HRAS (p = 0.023) and NRAS (p = 0.045) were noted in group 1 (PDT), compared with the control group. Treatment by laser alone induce down-regulation of CASP3 (p < 0.05), BAX (p < 0.05), BCL2 (p > 0.05), HRAS (p > 0.05) and NRAS (p > 0.05).

CONCLUSION

PDT caused down-regulation of NRAS, HRAS and BCL2 and over-expression of CASP3 and BAX genes at mRNA levels in HNSCC cell line. The present study raises the possibility that the role of MB on BCL2 down-regulation and BAX and CASP3 over-expression was higher than laser alone while it seems that laser alone was more effective than MB in HRAS and NRAS down-regulation.

Cervical cancer: a meta-analysis, therapy and future of nanomedicine

Cervical cancer is one of the leading causes of female death, with an annual mortality rate exceeding 200,000 in developing communities. Despite the past decade bearing witness to a reduction in cervical cancer cases throughout developed countries, the prevalence in developing countries continues to rapidly rise. The increase in cervical cancer cases is attributed to the lack of financial resources and the unavoidable risk factors of the disease. Traditional means of anticancer therapy are compromised by reduced drug potency, non-specificity, negative side effects and the development of multiple drug resistance (MDR), which leads to a decrease in the long-term anticancer therapeutic efficacy. Recent advances in nanomedicine have elucidated the potential of nanoparticles to reduce the side effects and improve the survival rate of patients, by enhancing selective delivery and uptake of photosensitive, therapeutic and genetic material to cervical cancer cells, thereby enhancing antitumour efficiency. This review paper analyses the risk factors and epidemiology of cervical cancer globally, especially in developing communities, whilst demonstrating the enhanced anticancer treatment using selected nanoparticles.

Role of Photoactive Phytocompounds in Photodynamic Therapy of Cancer

Cancer is one of the greatest life-threatening diseases conventionally treated using chemo- and radio-therapy. Photodynamic therapy (PDT) is a promising approach to eradicate different types of cancers. PDT requires the administration of photosensitisers (PSs) and photoactivation using a specific wavelength of light in the presence of molecular oxygen. This photoactivation exerts an anticancer effect via apoptosis, necrosis, and autophagy of cancer cells. Recently, various natural compounds that exhibit photosensitising potentials have been identified. Photoactive substances derived from medicinal plants have been found to be safe in comparison with synthetic compounds. Many articles have focused on PDT mechanisms and types of PSs, but limited attention has been paid to the phototoxic activities of phytocompounds. The reduced toxicity and side effects of natural compounds inspire the researchers to identify and use plant extracts or phytocompounds as a potent natural PS candidate for PDT. This review focusses on the importance of common photoactive groups (furanocoumarins, polyacetylenes, thiophenes, curcumins, alkaloids, and anthraquinones), their phototoxic effects, anticancer activity and use as a potent PS for an effective PDT outcome in the treatment of various cancers.

Potentiality, Limitations, and Consequences of Different Experimental Models to Improve Photodynamic Therapy for Cancer Treatment in Relation to Antiangiogenic Mechanism

The relevance of experimentally gained information represents a long-term debating issue in the field of molecular biology research. The loss of original conditions in the in vitro environment affects various biological mechanisms and cellular interactions. Consequently, some biochemical mechanisms are lost or critically altered. Analyses in these modified conditions could, therefore, distort the relevancy of experimentally gained information. In some cases, the similarities with original conditions are so small that utilization of simpler in vitro models seems impossible, or could occur in a very limited way. To conclude, the study of more complex phenomena places higher demands on the complexity of the experimental model. The latest information highlights the fact that the tumor angiogenesis mechanism has very complex features. This complexity can be associated with a wide range of angiogenic factors expressed by a variety of malignant and non-malignant cells. Our article summarizes the results from various experimental models that were utilized to analyze a photodynamic therapy effect on tumor angiogenic mechanisms. Additionally, based on the latest information, we present the most important attributes and limitations of utilized experimental models. We also evaluate the essential problems associated with angiogenic mechanism induction after photodynamic therapy application.

Dimeric prodrug-based nanomedicines for cancer therapy

With the rapid development of conjugation chemistry and biomedical nanotechnology, prodrug-based nanosystems (PNS) have emerged as promising drug delivery nanoplatforms. Dimeric prodrug, as an emerging branch of prodrug, has been widely investigated by covalently conjugating two same or different drug molecules. In recent years, great progress has been made in dimeric prodrug-based nanosystems (DPNS) for cancer therapy. Many advantages offered by DPNS have significantly facilitated the delivery efficiency of anticancer drugs, such as high drug loading capacity, favorable pharmacokinetics, tumor stimuli-sensitive drug release and facile combination theranostics. Given the rapid developments in this field, we here outline the latest updates of DPNS in cancer treatment, focusing on dimeric prodrug-encapsulated nanosystems, dimeric prodrug-nanoassemblies and tumor stimuli-responsive DPNS. Moreover, the design principle, advantages and challenges of DPNS for clinical cancer therapy are also highlighted.

Natural photosensitizers in photodynamic therapy: In vitro activity against monolayers and spheroids of human colorectal adenocarcinoma SW480 cells

Photodynamic Therapy (PDT), is a treatment option for cancer.It involves the photochemical interaction of light, photosensitizer (PS) and molecular oxygen to produce radical species as well as singlet oxygen which induce cell death. Anthraquinones (AQs) have been extensively studied with respect to their UV/Vis absorption characteristics and their photosensitizing properties in photodynamic reactions. We study the photoactivity of different natural AQs (Parietin, Soranjidiol and Rubiadin) in treating monolayers and multicellular tumor spheroids (MCTSs). Rubiadin and soranjidiol were isolated and purified from the stem and leaves of Heterophyllae pustulata, and PTN was from the liquen Teloschistes flavicans by using repeated combination of several chromatographic techniques. Monolayer and spheroids of human colorectal adenocarcinoma SW480 cells were incubated with different concentrations of the AQs and then irradiated at room temperature. 24 h post-PDT cell viability, nuclear morphology and type of cell death were analyzed. We observed that Soranjidiol and Rubiadin showed no significant difference in the photosensitizing ability on monoculture of colon cancer cells (LD₈₀ at 50 μM and 10 J/cm², for both AQs). Nevertheless, for Parietin (PTN) LD₈₀ was achieved at (20 μM using the same light dose (10 J/cm²). The death mechanism induced post-PDT was necrosis by use of Soranjidol and Rubiadin and apoptosis by use of PTN. Furthermore, in MCTSs of 300 and 900 μm, the treatment PTN- PDT produces the greatest cytotoxic effect. The three AQs analyzed could be promising chemotherapeutic candidates as anticancer PDT agents.

LMCT transition-based red-light photochemotherapy using a tumour-selective ferrocenyl iron(iii) coumarin conjugate

A rationally designed iron(iii) complex (2a) with pendant ferrocene and naturally occurring coumarin (esculetin) shows LMCT transition-based mitochondria-targeted red-light (600-720 nm) induced apoptotic toxicity against cancer cells but remains innocuous in the dark and to normal cells.

Photoinduced damage of AsLOV2 domain is accompanied by increased singlet oxygen production due to flavin dissociation

Flavin mononucleotide (FMN) belongs to the group of very efficient endogenous photosensitizers producing singlet oxygen, ¹O₂, but with limited ability to be targeted. On the other hand, in genetically-encoded photosensitizers, which can be targeted by means of various tags, the efficiency of FMN to produce ¹O₂ is significantly diminished due to its interactions with surrounding amino acid residues. Recently, an increase of ¹O₂ production yield by FMN buried in a protein matrix was achieved by a decrease of quenching of the cofactor excited states by weakening of the protein-FMN interactions while still forming a complex. Here, we suggest an alternative approach which relies on the blue light irradiation-induced dissociation of FMN to solvent. This dissociation unlocks the full capacity of FMN as ¹O₂ producer. Our suggestion is based on the study of an irradiation effect on two variants of the LOV2 domain from Avena sativa; wild type, AsLOV2 wt, and the variant with a replaced cysteine residue, AsLOV2 C450A. We detected irradiation-induced conformational changes as well as oxidation of several amino acids in both AsLOV2 variants. Detailed analysis of these observations indicates that irradiation-induced increase in ¹O₂ production is caused by a release of FMN from the protein. Moreover, an increased FMN dissociation from AsLOV2 wt in comparison with AsLOV2 C450A points to a role of C450 oxidation in repelling the cofactor from the protein.

Physicochemical stability of bioadhesive thermoresponsive platforms for methylene blue and hypericin delivery in photodynamic therapy

Hypericin (Hyp), a natural hydrophobic and photoactive pigment, and methylene blue (MB), a hydrophilic cationic dye, are utilized as photosensitizer (PS) for photodynamic therapy of cancer. Bioadhesive and thermoresponsive polymeric systems can improve the drug availability by increasing the contact time between the system and the mucosa and also controlling the drug release. In this work, an accelerated physicochemical stability study of binary polymeric systems composed of poloxamer 407 (Polox) and Carbopol 934 P (Carb) for MB or Hyp release was performed. Formulations were prepared containing Polox (20%, w/w), Carb (0.15%, w/w) and MB (0.25%, w/w) or Hyp (0.01%, W/W) and submitted to different stress conditions (5 ± 3 °C, 25 ± 2 °C and 40 ± 2 °C with relative humidity of 75 ± 5%) during 180 days. The samples were analyzed as macroscopic characteristics, photosensitizer content and mechanical properties by texture profile analysis. Both systems displayed decrease of photosensitizer content less than 5% during 180 days. MB-system showed an undefined reaction model, while Hyp-system displayed PS decay following a pseudo first-order reaction. Systems also displayed stable mechanical characteristics. The pharmaceutical analyses showed the good physicochemical stability of the bioadhesive platform for delivery Hyp and MB in photodynamic therapy.

Non-polar extracts of Nicotiana glauca (Solanaceae) induce apoptosis in human rhabdomyosarcoma cells

Abstract Rhabdomyosarcoma (RMS) is the most common soft-tissue tumour in children and adolescents. It originates in normal skeletal muscle from myogenic cells that have failed to fully differentiate, and it usually has a poor prognosis. Current RMS therapy has many adverse effects. Hence, new treatments are needed. Various pharmacological properties, such as analgesic, antineoplastic, antimicrobial, and antiparasitic properties, have been demonstrated in species of the Solanaceae family. We performed ethanolic extraction from leaves of Nicotiana glauca (Solanaceae), and the extract was successively partitioned with n-hexane, chloroform, and ethyl acetate. We evaluated the effects of extracts on RMS cells, and we found that the extracts trigger apoptosis. By bio-guided fractionation assays, we identified the apoptotic agents. Morphological assessment after apoptotic cell induction of cultured cells, mitochondrial and nuclear morphology by Mitotracker, and 4,6-diamidino-2-phenylindole (DAPI) staining, respectively, were analysed in fluorescent microscopy. The capacity of the cells to migrate or proliferate was analysed by the Petit assay, followed by methylene blue staining. NMR and GC-MS spectrometry were used to identify palmitic acid and scopoletin as the phytochemicals responsible for the observed effects. These results indicate that these compounds are apoptotic inducers and they could be useful as chemotherapeutic agents against muscle tumours.

Multifunctional phototheranostic nanomedicine for cancer imaging and treatment

Cancer, as one of the most life-threatening diseases, shows a high fatality rate around the world. When improving the therapeutic efficacy of conventional cancer treatments, researchers also conduct extensive studies into alternative therapeutic approaches, which are safe, valid, and economical. Phototherapies, including photodynamic therapy (PDT) and photothermal therapy (PTT), are tumor-ablative and function-reserving oncologic interventions, showing strong potential in clinical cancer treatment. During phototherapies, the non-toxic phototherapeutic agents can be activated upon light irradiation to induce cell death without causing much damage to normal tissues. Besides, with the rapid development of nanotechnology in the past decades, phototheranostic nanomedicine also has attracted tremendous interests aiming to continuously refine their performance. Herein, we reviewed the recent progress of phototheranostic nanomedicine for improved cancer therapy. After a brief introduction of the therapeutic principles and related phototherapeutic agents for PDT and PTT, the existing works on developing of phototheranostic nanomedicine by mainly focusing on their categories and applications, particularly on phototherapy-synergized cancer immunotherapy, are comprehensively reviewed. More importantly, a brief conclusion and future challenges of phototheranostic nanomedicine from our point of view are delivered in the last part of this article.

Recent advances in ultra-small fluorescent Au nanoclusters toward oncological research

Au nanoclusters possess a series of excellent properties owing to their size being comparable to the Fermi wavelength of electrons. For example, they show excellent biocompatibility, optical stability, large Stokes shift, intense size-dependent emission and monodispersion, and thus could effectively compensate for the shortcomings of traditional organic fluorescent dyes and fluorescent quantum. In this review, we detail the latest developments of Au nanoclusters employed in the field of biomedicine, especially in oncology research, by summarizing the application of imaging, sensing and drug delivery based on their excellent luminescent properties and unique structural features. We also discuss the significant work relating to Au NCs that now is being devoted in other therapeutic strategies, such as radiotherapy, photothermal therapy and photodynamic therapy, for example. It is anticipated that this review will provide new insights and theoretical guidance to allow the advantages of Au nanoclusters to be realized in oncotherapy.

[Effect of miskleron (clofibrate) on dimethylhydrazine induction of intestinal tumors in rats]

In this review, we report on the complexity of breast cancer stem cells as key cells in the emergence of a chemoresistant tumor phenotype, and as a result, the appearance of distant metastasis in breast cancer patients. The search for mechanisms that increase sensitivity to chemotherapy and also allow activation of the tumor-specific immune response is of high priority. As we observed throughout this review, natural products isolated or in standardized extracts, such as P2Et or others, could act synergistically, increasing tumor sensitivity to chemotherapy, recovering the tumor microenvironment, and participating in the induction of a specific immune response. This, in turn, would lead to the destruction of cancer stem cells and the decrease in metastasis.

Source of Data: Relevant studies were found using the following keywords or medical subject headings (MeSH) in PubMed, and Google Scholar: “immune response” and “polyphenols” and “natural products” and “BCSC” and “therapy” and “metabolism” and “immunogenic cell death.” The focus was primarily on the most recent scientific publication.