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Tumor cell survival pathways activated by photodynamic therapy: a molecular basis for pharmacological inhibition strategies.

ABSTRACT: Photodynamic therapy (PDT) has emerged as a promising alternative to conventional cancer therapies such as surgery, chemotherapy, and radiotherapy. PDT comprises the administration of a photosensitizer, its accumulation in tumor tissue, and subsequent irradiation of the photosensitizer-loaded tumor, leading to the localized photoproduction of reactive oxygen species (ROS). The resulting oxidative damage ultimately culminates in tumor cell death, vascular shutdown, induction of an antitumor immune response, and the consequent destruction of the tumor. However, the ROS produced by PDT also triggers a stress response that, as part of a cell survival mechanism, helps cancer cells to cope with the PDT-induced oxidative stress and cell damage. These survival pathways are mediated by the transcription factors activator protein 1 (AP-1), nuclear factor E2-related factor 2 (NRF2), hypoxia-inducible factor 1 (HIF-1), nuclear factor ?B (NF-?B), and those that mediate the proteotoxic stress response. The survival pathways are believed to render some types of cancer recalcitrant to PDT and alter the tumor microenvironment in favor of tumor survival. In this review, the molecular mechanisms are elucidated that occur post-PDT to mediate cancer cell survival, on the basis of which pharmacological interventions are proposed. Specifically, pharmaceutical inhibitors of the molecular regulators of each survival pathway are addressed. The ultimate aim is to facilitate the development of adjuvant intervention strategies to improve PDT efficacy in recalcitrant solid tumors.

SUBMITTER: Broekgaarden M

PROVIDER: S-EPMC4661210 | biostudies-literature | 2015 Dec

REPOSITORIES: biostudies-literature

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Tumor cell survival pathways activated by photodynamic therapy: a molecular basis for pharmacological inhibition strategies.

Broekgaarden Mans M Weijer Ruud R van Gulik Thomas M TM Hamblin Michael R MR Heger Michal M

Cancer metastasis reviews 20151201 4

Photodynamic therapy (PDT) has emerged as a promising alternative to conventional cancer therapies such as surgery, chemotherapy, and radiotherapy. PDT comprises the administration of a photosensitizer, its accumulation in tumor tissue, and subsequent irradiation of the photosensitizer-loaded tumor, leading to the localized photoproduction of reactive oxygen species (ROS). The resulting oxidative damage ultimately culminates in tumor cell death, vascular shutdown, induction of an antitumor immun ...[more]

PMID: 26516076

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Project description:Photodynamic therapy (PDT) of solid cancers comprises the administration of a photosensitizer followed by illumination of the photosensitizerreplete tumor with laser light. This induces a state of local oxidative stress, culminating in the destruction of tumor tissue and microvasculature and induction of an anti-tumor immune response. However, some tumor types, including perihilar cholangiocarcinoma, are relatively refractory to PDT, which may be attributable to the activation of survival pathways in tumor cells following PDT (i.e., activator protein 1 (AP-1)-, nuclear factor of kappa light polypeptide gene enhancer in B-cells (NF-ÎºB)-, hypoxia-inducible factor 1-alpha (HIF-1Î±)-, nuclear factor (erythroid-derived 2)-like 2 (NFE2L2), and unfolded protein response-mediated pathways). To assess the activation of survival pathways after PDT, human perihilar cholangiocarcinoma (SK-ChA-1) cells were subjected to PDT with zinc phthalocyanine (ZnPC)-encapsulating liposomes. Following a 30-minute incubation with liposomes, the cells were either left untreated or treated at low (50 mW) or high (500 mW) laser power (cumulative light dose of 15 J/cm2). Cells were harvested 90 minutes post-PDT and whole genome expression analysis was performed using Illumina HumanHT-12 v4 expression beadchips. Hilar cholangiocarcinoma (SK-ChA-1) cells were incubated with PBS (control group) or 500 Î¼M zinc phthalocyanine (ZnPC)-encapsulating liposomes (ZnPC-ITLs, final lipid concentration). After 30 minutes, cells that were incubated with ZnPC-ITLs were either kept in the dark (ITL group) or were treated with 500-mW (ITL 500) or 50-mW (ITL 50) laser light (n = 3 per group, cumulative light dose of 15 J/cm2). Ninety minutes after photodynamic therapy, total cellular RNA was isolated and gene expression levels were analyzed by using the Illumina HumanHT-12 v4 platform. The data was analyzed in the context of survival signalling and comparisons were made with the control group.

Project description:The low tissue penetration depth of external excitation light severely hinders the sensitivity of fluorescence imaging (FL) and the efficacy of photodynamic therapy (PDT) in vivo; thus, rational theranostic platforms that overcome the light penetration depth limit are urgently needed. To overcome this crucial problem, we designed a self-luminescing nanosystem (denoted POCL) with near-infrared (NIR) light emission and singlet oxygen (1O2) generation abilities utilizing an intraparticle relayed resonance energy transfer strategy. Methods: Bis[3,4,6-trichloro-2-(pentyloxycarbonyl) phenyl] oxalate (CPPO) as a chemical energy source with high reactivity toward H2O2, poly[(9,9'-dioctyl-2,7-divinylene-fluorenylene)-alt-2-methoxy- 5-(2-ethyl-hexyloxy)-1,4-phenylene] (PFPV) as a highly efficient chemiluminescence converter, and tetraphenylporphyrin (TPP) as a photosensitizer with NIR emission and 1O2 generation abilities were coencapsulated by self-assembly with poly(ethyleneglycol)-co-poly(caprolactone) (PEG-PCL) and folate-PEG-cholesterol to form the POCL nanoreactor, with folate as the targeting group. A series of in vitro and in vivo analyses, including physical and chemical characterizations, tumor targeting ability, tumor microenvironment activated imaging and photodynamic therapy, as well as biosafety, were systematically investigated to characterize the POCL. Results: The POCL displayed excellent NIR luminescence and 1O2 generation abilities in response to H2O2. Therefore, it could serve as a specific H2O2 probe to identify tumors through chemiluminescence imaging and as a chemiluminescence-driven PDT agent for inducing tumor cell apoptosis to inhibit tumor growth due to the abnormal overproduction of H2O2 in the tumor microenvironment. Moreover, the folate ligand on the POCL surface can further improve the accumulation at the tumor site via a receptor-mediated mechanism, thus enhancing tumor imaging and the therapeutic effects both in vitro and in vivo but without any observable systemic toxicity. Conclusion: The nanosystem reported here might serve as a targeted, smart, precise, and noninvasive strategy triggered by the tumor microenvironment rather than by an outside light source for cancer NIR imaging and PDT treatment without limitations on penetration depth.

Dataset Information

Tumor cell survival pathways activated by photodynamic therapy: a molecular basis for pharmacological inhibition strategies.

Publications

Tumor cell survival pathways activated by photodynamic therapy: a molecular basis for pharmacological inhibition strategies.

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