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Activated T cells exhibit increased uptake of silicon phthalocyanine Pc 4 and increased susceptibility to Pc 4-photodynamic therapy-mediated cell death.

ABSTRACT: Photodynamic therapy (PDT) is an emerging treatment for malignant and inflammatory dermal disorders. Photoirradiation of the silicon phthalocyanine (Pc) 4 photosensitizer with red light generates singlet oxygen and other reactive oxygen species to induce cell death. We previously reported that Pc 4-PDT elicited cell death in lymphoid-derived (Jurkat) and epithelial-derived (A431) cell lines in vitro, and furthermore that Jurkat cells were more sensitive than A431 cells to treatment. In this study, we examined the effectiveness of Pc 4-PDT on primary human CD3(+) T cells in vitro. Fluorometric analyses of lysed T cells confirmed the dose-dependent uptake of Pc 4 in non-stimulated and stimulated T cells. Flow cytometric analyses measuring annexin V and propidium iodide (PI) demonstrated a dose-dependent increase of T cell apoptosis (6.6-59.9%) at Pc 4 doses ranging from 0-300 nM. Following T cell stimulation through the T cell receptor using a combination of anti-CD3 and anti-CD28 antibodies, activated T cells exhibited increased susceptibility to Pc 4-PDT-induced apoptosis (10.6-81.2%) as determined by Pc 4 fluorescence in each cell, in both non-stimulated and stimulated T cells, Pc 4 uptake increased with Pc 4 dose up to 300 nM as assessed by flow cytometry. The mean fluorescence intensity (MFI) of Pc 4 uptake measured in stimulated T cells was significantly increased over the uptake of resting T cells at each dose of Pc 4 tested (50, 100, 150 and 300 nM, p < 0.001 between 50 and 150 nM, n = 8). Treg uptake was diminished relative to other T cells. Cutaneous T cell lymphoma (CTCL) T cells appeared to take up somewhat more Pc 4 than normal resting T cells at 100 and 150 nm Pc 4. Confocal imaging revealed that Pc 4 localized in cytoplasmic organelles, with approximately half of the Pc 4 co-localized with mitochondria in T cells. Thus, Pc 4-PDT exerts an enhanced apoptotic effect on activated CD3(+) T cells that may be exploited in targeting T cell-mediated skin diseases, such as cutaneous T cell lymphoma (CTCL) or psoriasis.

SUBMITTER: Soler DC

PROVIDER: S-EPMC4928582 | biostudies-literature | 2016 Jun

REPOSITORIES: biostudies-literature

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Activated T cells exhibit increased uptake of silicon phthalocyanine Pc 4 and increased susceptibility to Pc 4-photodynamic therapy-mediated cell death.

Soler David C DC Ohtola Jennifer J Sugiyama Hideaki H Rodriguez Myriam E ME Han Ling L Oleinick Nancy L NL Lam Minh M Baron Elma D ED Cooper Kevin D KD McCormick Thomas S TS

Photochemical & photobiological sciences : Official journal of the European Photochemistry Association and the European Society for Photobiology 20160510 6

Photodynamic therapy (PDT) is an emerging treatment for malignant and inflammatory dermal disorders. Photoirradiation of the silicon phthalocyanine (Pc) 4 photosensitizer with red light generates singlet oxygen and other reactive oxygen species to induce cell death. We previously reported that Pc 4-PDT elicited cell death in lymphoid-derived (Jurkat) and epithelial-derived (A431) cell lines in vitro, and furthermore that Jurkat cells were more sensitive than A431 cells to treatment. In this stud ...[more]

PMID: 27161819

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Project description:The current clinical mainstays for cancer treatment, namely, surgical resection, chemotherapy, and radiotherapy, can cause significant trauma, systemic toxicity, and functional/cosmetic debilitation of tissue, especially if repetitive treatment becomes necessary due to tumor recurrence. Hence there is significant clinical interest in alternate treatment strategies like photodynamic therapy (PDT) which can effectively and selectively eradicate tumors and can be safely repeated if needed. We have previously demonstrated that the second-generation photosensitizer Pc 4 (silicon phthalocyanine 4) can be formulated within polymeric micelles, and these micelles can be specifically targeted to EGFR-overexpressing cancer cells using GE11 peptide ligands, to enhance cell-specific Pc 4 delivery and internalization. In the current study, we report on the in vitro optimization of the EGFR-targeting, Pc 4 loading of the micellar nanoformulation, along with optimization of the corresponding photoirradiation conditions to maximize Pc 4 delivery, internalization, and subsequent PDT-induced cytotoxicity in EGFR-overexpressing cells in vitro. In our studies, absorption and fluorescence spectroscopy were used to monitor the cell-specific uptake of the GE11-decorated Pc 4-loaded micelles and the cytotoxic singlet oxygen production from the micelle-encapsulated Pc 4, to determine the optimum ligand density and Pc 4 loading. It was found that the micelle formulations bearing 10 mol % of GE11-modified polymer component resulted in the highest cellular uptake in EGFR-overexpressing A431 cells within the shortest incubation periods. Also, the loading of ? 50 ?g of Pc 4 per mg of polymer in these micellar formulations resulted in the highest levels of singlet oxygen production. When formulations bearing these optimized parameters were tested in vitro on A431 cells for PDT effect, a formulation dose containing 400 nM Pc 4 and photoirradiation duration of 400 s at a fluence of 200 mJ/cm(2) yielded close to 100% cell death.

Dataset Information

Activated T cells exhibit increased uptake of silicon phthalocyanine Pc 4 and increased susceptibility to Pc 4-photodynamic therapy-mediated cell death.

Publications

Activated T cells exhibit increased uptake of silicon phthalocyanine Pc 4 and increased susceptibility to Pc 4-photodynamic therapy-mediated cell death.

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