PDT induced bystander effect on human xenografted colorectal tumors as evidenced by sodium MRI

Photodynamic Therapy for Colorectal Cancer: An Update and a Look to the Future

This review provides an update on the current state of photodynamic therapy (PDT) for colorectal cancer (CRC) and explores potential future directions in this field. PDT has emerged as a promising minimally invasive treatment modality that utilizes photosensitizers and specific light wavelengths to induce cell death in targeted tumor tissues. In recent years, significant progress has been made in understanding the underlying mechanisms, optimizing treatment protocols, and improving the efficacy of PDT for CRC. This article highlights key advancements in PDT techniques, including novel photosensitizers, light sources, and delivery methods. Furthermore, it discusses ongoing research efforts and potential future directions, such as combination therapies and nanotechnology-based approaches. By elucidating the current landscape and providing insights into future directions, this review aims to guide researchers and clinicians in harnessing the full potential of PDT for the effective management of CRC.

Understanding the Photodynamic Therapy Induced Bystander and Abscopal Effects: A Review

Photodynamic therapy (PDT) is a clinically approved minimally/non-invasive treatment modality that has been used to treat various conditions, including cancer. The bystander and abscopal effects are two well-documented significant reactions involved in imparting long-term systemic effects in the field of radiobiology. The PDT-induced generation of reactive oxygen and nitrogen species and immune responses is majorly involved in eliciting the bystander and abscopal effects. However, the results in this regard are unsatisfactory and unpredictable due to several poorly elucidated underlying mechanisms and other factors such as the type of cancer being treated, the irradiation dose applied, the treatment regimen employed, and many others. Therefore, in this review, we attempted to summarize the current knowledge regarding the non-targeted effects of PDT. The review is based on research published in the Web of Science, PubMed, Wiley Online Library, and Google Scholar databases up to June 2023. We have highlighted the current challenges and prospects in relation to obtaining clinically relevant robust, reproducible, and long-lasting antitumor effects, which may offer a clinically viable treatment against tumor recurrence and metastasis. The effectiveness of both targeted and untargeted PDT responses and their outcomes in clinics could be improved with more research in this area.

Increased PDT Efficacy When Associated with Nitroglycerin: A Study on Retinoblastoma Xenografted on Mice

Purposes: The aim of the study was to assess the efficacy of a treatment protocol that combines photodynamic therapy (PDT) and nitroglycerin (NG) on human retinoblastoma tumors xenografted on mice. We aimed to increase the PDT efficiency (in our least treatment-responsive retinoblastoma line) with better PS delivery to the tumor generated by NG, which is known to dilate vessels and enhance the permeability and retention of macromolecules in solid tumors. Methods: In vivo follow-up of the therapeutic effects was performed by sodium MRI, which directly monitors variations in sodium concentrations non-invasively and can be used to track the tumor response to therapy. NG ointment was applied one hour before PDT. The PDT protocol involves double-tumor targeting, i.e., cellular and vascular. The first PS dose was injected followed by a second one, separated by a 3 h interval. The timelapse allowed the PS molecules to penetrate tumor cells. Ten minutes after the second dose, the PS was red-light-activated. Results: In this study, we observed that the PDT effect was enhanced by applying nitroglycerin ointment to the tumor-bearing animal’s skin. PDT initiates the bystander effect on retinoblastomas, and NG increases this effect by increasing the intratumoral concentration of PS, which induces a higher production of ROS in the illuminated region and thus increases the propagation of the cell death signal deeper into the tumor (bystander effect).

A Novel Mechanism of the c-Myc/NEAT1 Axis Mediating Colorectal Cancer Cell Response to Photodynamic Therapy Treatment

Photodynamic therapy (PDT) is considered a potential treatment regimen for colorectal cancer cases (CRC). p53 signaling and the miR-124/iASPP axis play an essential role in the PDT resistance of CRC cells. PDT treatment downregulated NEAT1 expression in p53^wt HCT116 and RKO cells. In these two cell lines, NEAT1 silencing enhanced the suppressive effects of PDT on cell viability and apoptosis. Within the subcutaneously implanted tumor model, NEAT1 silencing enhanced PDT-induced suppression on tumor growth. Regarding p53-deleted HCT116 cells, PDT only moderately affected cell proliferation but induced downregulation of NEAT1. NEAT1 directly targeted miR-124, acting as a ceRNA, competing with iASPP for miR-124 binding, and counteracting miR-124-mediated repression on iASPP under PDT treatment. NEAT1 silencing was enhanced, whereas miR-124 inhibition attenuated PDT effects on CRC cells; miR-124 inhibition significantly reversed the roles of NEAT1 silencing in PDT-treated CRC cells. miR-124 negatively correlated with NEAT1 and iASPP, respectively, whereas NEAT1 and iASPP positively correlated with each other. PDT downregulated c-Myc in CRC cells, and c-Myc activated the transcription of NEAT1 through the targeting of its promoter region. Within p53^mut SW480 cells, PDT failed to alter cell viability and apoptosis but still downregulated c-Myc, NEAT1, and iASPP and upregulated miR-124. In p53 mutant high-abundant CRC tissues, c-Myc and NEAT1 were up-regulated, and miR-124 was downregulated. In c-Myc high-abundant CRC tissues, NEAT1 and iASPP were up-regulated, and miR-124 was downregulated. The critical role of the c-Myc/NEAT1 axis in mediating CRC response to PDT treatment via the miR-124/iASPP/p53 feedback loop was conclusively demonstrated.

The nanomaterial-induced bystander effects reprogrammed macrophage immune function and metabolic profile

Bystander effects in biological systems are the responses shown by nontargeted neighboring cells, and critical to the bio-nano interface interactions. In addition to direct effects, bystander effects also determine the design, applications and safety of nanomaterials, although the related information of nanomaterial-induced bystander effects remain largely unknown. A coculture system of A549 and THP-1 was established to mimic the lung microenvironment to study the bystander effects of WS₂ nanosheets (representative transition-metal dichalcogenide nanosheets) on microenvironment macrophages during the inhalation exposure or the nanomaterial biomedical application in the lung. Lung cells exposed to WS₂ nanosheet resulted in an increase in reactive oxygen species and the depolarization of mitochondrial membrane potential in neighboring macrophages. Bystander exposure also induced macrophage polarization toward the anti-inflammatory M2 phenotype, which is adverse to disease therapy. Metabolomics showed that WS₂ nanosheets disturbed the energy metabolism and amino acid metabolism of macrophages, consistent with the metabolic characteristics of M2 macrophages. Nitric oxide-transforming growth factor-β1 played an important mediator in the bystander effects. Importantly, WS₂ nanosheet bystander exposure affected macrophage phagocytosis and migration and altered the macrophage immune response to endotoxin. This study improves the current understanding of bio-nano interactions and highlights the importance of neighboring cell responses, allowing us to use the maximum benefits of nanomaterials while limiting their adverse bystander effects.

Mannose distribution in glycoconjugated tetraphenylporphyrins governs their uptake mechanism and phototoxicity

Tetraphenylporphyrins (TPPs) have been proposed for the treatment of retinoblastoma by photodynamic therapy. Glycoconjugated compounds were synthesized for improving TPP solubility and amphipathy, and to specifically target mannose receptors overexpressed at the surface of cells. The efficiency of four TPP derivatives with different chemical structures was compared by phototoxicity tests and flow cytometry experiments. Interestingly, the absence/presence and distribution of saccharide moieties in the various compounds affected differently their mechanism of interaction with cancer cells and their phototoxic efficiency. For glycodendrimeric TPP-1 and TPP-2 incubated with retinoblastoma cells, a fast two-step uptake-equilibrium process was observed, whereas for a dendrimeric TPP without saccharide moieties (TPP-1c) and a glycoconjugated compound with no dendrimeric structure (TPP(DegMan)[Formula: see text] uptake was very slow. The difference in uptake profiles and kinetics between TPP-1c on the one hand and TPP-1 and TPP-2 on the other hand would account for the interaction of the two glycodendrimeric compounds with a mannose receptor. These TPPs encapsulated in endosomes would induce less damage to cells upon illumination. TPP(DegMan)[Formula: see text] showed the highest phototoxicity, but its efficiency was unaffected by pretreatment of cells by mannan. The penetration of this glycoconjugated compound in cells and its phototoxic effect appeared independent of its interaction with a mannose receptor. Thus, if glycoconjugation influenced TPPs behavior in solution and interaction with serum proteins, phototoxicity was not necessarily related to upfront molecular recognition.

Development and evaluation of a low-cost, portable, LED-based device for PDT treatment of early-stage oral cancer in resource-limited settings

BACKGROUND

Photodynamic therapy (PDT) using δ-aminolevulinic acid (ALA) photosensitization has shown promise in clinical studies for the treatment of early-stage oral malignancies with fewer potential side effects than traditional therapies. Light delivery to oral lesions can also carried out with limited medical infrastructure suggesting the potential for implementation of PDT in global health settings.

OBJECTIVES

We sought to develop a cost-effective, battery-powered, fiber-coupled PDT system suitable for intraoral light delivery enabled by smartphone interface and embedded electronics for ease of operation.

METHODS

Device performance was assessed in measurements of optical power output, spectral stability, and preclinical assessment of PDT response in ALA-photosensitized squamous carcinoma cell cultures and murine subcutaneous tumor xenografts.

RESULTS

The system achieves target optoelectronic performance with a stable battery-powered output of approximately 180 mW from the fiber tip within the desired spectral window for PpIX activation. The device has a compact configuration, user friendly operation and flexible light delivery for the oral cavity. In cell culture, we show that the overall dose-response is consistent with established light sources and complete cell death of ALA photosensitized cells can be achieved in the irradiated zone. In vivo PDT response (reduction in tumor volume) is comparable with a commercial 635 nm laser.

CONCLUSIONS

We developed a low-cost, LED-based, fiber-coupled PDT light delivery source that has stable output on battery power and suitable form factor for deployment in rural and/or resource-limited settings. Lasers Surg. Med. 9999:1-7, 2018. © 2018 Wiley Periodicals, Inc.

A glycoporphyrin story: from chemistry to PDT treatment of cancer mouse models

Glycoporphyrin: from bench to preclinical studies on PDX xenografted on mice.

Wild-type and mutant p53 differentially modulate miR-124/iASPP feedback following pohotodynamic therapy in human colon cancer cell line

Colorectal cancer (CRC) is a most common digestive system malignant tumor. p53 mutation has essential role in cancers and is frequently observed in CRC and presents a huge challenge. p53 mutation has been reported to attenuate the inhibitory effect of photofrin-based photodynamic therapy (PDT). p53 mutation-induced gain of function brings up the dysfunction of carcinogenic factors, including miRNAs. Our research found that PDT suppressed CRC cell viability, reduced the tumor size and prolonged the survival time, all of which could be attenuated by p53 mutation or deletion. After p53 mutation or deletion, several miRNA expression levels were downregulated, among which miR-124 was the most strongly downregulated, whereas iASPP expression was upregulated. p53 binds to the promoter of miR-124 to promote its expression and then inhibited iASPP expression, so as to amplify the inhibitory effect of PDT on wild-type p53 cells. In p53-mutant or -deleted cells, this binding no longer worked to promote miR-124 expression, and iASPP expression increased, finally resulted in promoted CRC cell viability upon PDT. The interactive modulation among miR and iASPP in p53-mutant or -deleted cells may serve as a crucial pathway, which mediates therapy resistance when p53 is mutated or deleted, in the process of PDT treatment of CRC.

Photonanomedicine: a convergence of photodynamic therapy and nanotechnology

As clinical nanomedicine has emerged over the past two decades, phototherapeutic advancements using nanotechnology have also evolved and impacted disease management. Because of unique features attributable to the light activation process of molecules, photonanomedicine (PNM) holds significant promise as a personalized, image-guided therapeutic approach for cancer and non-cancer pathologies. The convergence of advanced photochemical therapies such as photodynamic therapy (PDT) and imaging modalities with sophisticated nanotechnologies is enabling the ongoing evolution of fundamental PNM formulations, such as Visudyne®, into progressive forward-looking platforms that integrate theranostics (therapeutics and diagnostics), molecular selectivity, the spatiotemporally controlled release of synergistic therapeutics, along with regulated, sustained drug dosing. Considering that the envisioned goal of these integrated platforms is proving to be realistic, this review will discuss how PNM has evolved over the years as a preclinical and clinical amalgamation of nanotechnology with PDT. The encouraging investigations that emphasize the potent synergy between photochemistry and nanotherapeutics, in addition to the growing realization of the value of these multi-faceted theranostic nanoplatforms, will assist in driving PNM formulations into mainstream oncological clinical practice as a necessary tool in the medical armamentarium.

Carbohydrate-conjugated porphyrin dimers: synthesis and photobiological evaluation for a potential application in one-photon and two-photon photodynamic therapy

We report the synthesis of bioconjugated zinc porphyrin dimers 1a-e designed as photosensitizers for one-photon and two-photon excited photodynamic therapy. These macrocycles are substituted with carbohydrate units (glucose, mannose, lactose) in order to target tumor cells over-expressing lectin membrane receptors. Polarity, singlet oxygen production and in vitro photocytotoxicity are studied to determine their photodynamic therapy potentiality.

Tumor targeting in photodynamic therapy. From glycoconjugated photosensitizers to glycodendrimeric one. Concept, design and properties

In this paper, we discuss the evolution over the last 15 years in the Curie Institute of the concept, the development of the design and some properties of glycoconjugated photosensitizers with the aim to optimize the tumor targeting in photodynamic therapy. By this research, we have shown that specific interactions between a mannose-lectin and trimannosylglycodendrimeric porphyrins contributed to a larger extent than non-specific ones to the overall interaction of a glycosylated tetraarylporphyrin with a membrane. The studies of in vitro photocytotoxicity showed the relevance of the global geometry of the photosensitizer, the number and position of the linked glycopyranosyl groups on the chromophore and their lipophilicity. The two best compounds appeared to be porphyrins bearing three α-glycosyl groups on para-position of meso-phenyl via a flexible linker. Compound bearing α-manosyl moieties was evaluated successfully in two in vivo xenografted animal models of human retinoblastoma and colorectal cancers. Conversely, the presence on the chromophore of three sugars via a glycodendrimeric moiety induced a potential cluster effect, but decreased the in vitro photoefficiency despite a good affinity for a mannose-lectin.