Role of type I & type II reactions in DNA damage and activation of Caspase 3 via mitochondrial pathway induced by photosensitized benzophenone

Involvement of type-1 pathway in phototoxicity of benzo[ghi]perylenean ingredient of tattoo ink at ambient exposure of UVR and sunlight

Tattooing on different parts of the body is a very common fashion trend in all sections of society globally. Skin allergies and other related skin diseases are very common among tattoo users. Benzo[ghi]perylene (BP) is a PAH and an important component of tattoo ink that showed prominent absorption under ultraviolet radiation (UVR) region. Therefore, to provide safety to the skin, a thorough safety study of BP exposed under UVR and Sunlight is very essential to understand their hazardous impact on the skin. BP showed a strong absorption of UVA and UVB radiation of sunlight. It is photolabile and degraded under UVA, UVB, and Sunlight in progressing order of time (1-4 h) without generating any novel photoproducts. Further, BP showed a specific generation of O₂^.- and OH radicals via activation of type I photodynamic reaction under exposure to UVA, UVB and Sunlight. Photocytotoxicity results illustrated concentration-dependent cell viability reduction in all exposure conditions of UVA, UVB, and Sunlight, respectively. Fluorescent probes (2',7'-dichlorofluorescein diacetate and dihydroethidium) for intracellular reactive oxygen species (ROS) generation supported the involvement of ROS in the phototoxicity of BP in the HaCaT cell line. Hoechst staining showed significant genomic insult induced by BP under UVA and UVB. Photoexcited BP promoted cell cycle arrest in the G1 phase and induced apoptosis confirmed via acridine orange/ethidium bromide staining. The findings of gene expression also supported apoptotic cell death in photoexcited BP via an increase in the level of pro-apoptotic gene (Bax) and a decrease in the level of anti-apoptotic gene (Bcl-2). The aforementioned finding indicates that tattoo users should avoid using BP since it can cause skin damage/diseases if they are exposed to UVR or Sunlight while tattooing on the body.

Superoxide anion radical induced phototoxicity of 2,4,5,6-Tetraminopyrimidine sulfate via mitochondrial-mediated apoptosis in human skin keratinocytes at ambient UVR exposure

2,4,5,6-Tetraaminopyrimidine sulfate (TAPS) is worldwide the most commonly used developer in hair dyes. As skin is the major organ, which is directly exposed to these permanent hair dyes, a comprehensive dermal safety assessment is needed. Hereto, we studied the photosensitization potential and mechanism involved in dermal phototoxicity of TAPS exposed to the dark and UVA/UVB/Sunlight by using different in-chemico and mammalian (HaCaT) cells, as test systems. Our experimental outcomes illustrate that TAPS get photodegraded (LC-MS/MS) and specifically generated superoxide anion radical (O₂^•-) under UVA and UVB via type-I photodynamic reaction. The phototoxic potential of TAPS is measured through MTT, NRU, and LDH assays that depicted a significant reduction in cell viability at the concentration of 25 μg/ml and higher. Different cellular stainings (PI uptake, AO/EB, JC-1, NR uptake) suggested the role of mitochondrial-mediated apoptosis. Further, the transcriptomics study revealed upregulation of Apaf-1, Bax, Caspase 3, Caspase 9, Cytochrome c and downregulation of Bcl-2 and Catalase by TAPS treated cells that strengthen our findings. Thus, the above findings suggest that chronic application of TAPS may be hazardous for human skin and promote various skin diseases.

Sunscreen-induced expression and identification of photosensitive marker proteins in human keratinocytes under UV radiation

Solar ultraviolet (UV) radiation is the main factor of photocarcinogenesis, photoaging, and photosensitivity; thus protection from biological damaging UV radiation is a concern. Sunscreens containing UV filters are the most preferred means of photoprotection but the safety and efficacy of UV filters are in question. Benzophenone (BP) and its derivatives, namely, benzophenone 1 (BP1), is commonly used in sunscreens as a UV blocker. The aim of this study was to assess the effects of BP and BP1 on the differential expression of proteins in human keratinocytes (HaCaT cells) under exposure to ultraviolet A radiation. Photosensitive proteins were screened from HaCaT cells by two-dimensional (2-D) gel electrophoresis, and identification of these differentially expressed proteins was performed by matrix-assisted laser desorption/ionization-time-of-flight (MALDI-TOF)/TOF mass spectrometry. Protein identification was performed using the search program MASCOT and a database made of SUMO and GhJMJ12 amino acid sequences. Our results showed that the proteins involved directly or indirectly in apoptosis are 70 kDa heat shock protein, long-chain specific acyl-CoA dehydrogenase, serine/threonine-protein kinase, and FAM78A protein, which were upregulated in comparison to control HaCaT cells. The expressions of binding immunoglobulin protein, podocalyxin-like protein, actin, cytoplasmic, and calreticulin precursors were downregulated. The altered protein expression indicated that cell growth arrest and apoptosis were potential mechanisms of cytotoxicity and genotoxicity of BPs. The results of 2-D gel electrophoresis followed by mass spectrometry showed expression of novel proteins involved in promoting or initiating apoptotic pathways. Hence, we conclude that BPs should be avoided as a UV blocker from sunscreens because of its potential to promote apoptotic proteins in human skin keratinocytes.

Saccharomyces cerevisiae strains as bioindicators for titanium dioxide sunscreen photoprotective and photomutagenic assessment

Although several short-term assays are available for cosmetic photosafety assessment, cell models are usually highly sensitive to UV radiation, tending to overestimate both phototoxic and photomutagenic risks. In addition, these assays are performed with UV doses/fluences that do not correspond to actual environmental conditions. In this sense, Saccharomyces cerevisiae has already proved to be an interesting tool to predict photomutagenic potential of several compounds, including sunscreens. Yeast can support environmental UVB doses compatible with human daily sunlight exposure, allowing the use of irradiation sources to faithfully mimic the external conditions of ambient sunlight. Herein, we used a set of S. cerevisiae mutant strains sensitive to UVA, UVB and Solar Simulated Light sources in order to evaluate their potential as bioindicators for sunscreen development. The bioindicator potential of the strains was tested with the widely-used titanium dioxide inorganic sunscreen. The AWP001 (yno1) and LPW002 (ogg1yno1) strains obtained in this study stood out as promising experimental tools for the validation of this assay. Overall, our results evidenced a set of S. cerevisiae strains particularly useful for evaluating both photoprotective (efficacy) and photo/antiphotomutagenic (safety) potential of UV filters, meeting the industries and regulatory agencies demand for robust and efficient in vitro screening tests.

The effect of aging in primary human dermal fibroblasts

Skin aging is a complex process, and alterations in human skin due to aging have distinct characteristic as compared to other organs. The aging of dermal cells and the biological mechanisms involved in this process are key areas to understand skin aging. A large number of biological mechanisms, such as decreasing of protein synthesis of extracellular matrix or increasing of degradation, are known to be altered through skin aging. However, environmental influence can accelerate this characteristic phenotype. In this study, we analyzed primary human dermal fibroblasts in three different in-vitro aging models—UVB irradiation and accelerated proliferation of human dermal fibroblasts from young donors as well as from elderly donors—for the gene expression of COL1A1, COL1A2, COL3A1, COL4A1, COL7A1, MMP1, MMP2, MMP3, MMP7, MMP8, MMP9, MMP10, MMP12, MMP13, MMP14, TIMP1, TIMP2, TIMP3, TIMP4, IL1B, IL1A, IL6, IL8, IL10, PTGS2, TP53, CASP3, LMNA, SIRT1. We compared the gene expression levels with young control. Furthermore, the behavior of skin fibroblasts was also evaluated using cell growth rate. The findings reveal that the gene expression levels in skin fibroblasts was altered in the process of aging in all three in-vitro aging models, and the cell growth rate was reduced, suggesting that these methods can be employed to understand skin aging mechanisms as well as drug discovery screening method.

Photoexcited triclosan induced DNA damage and oxidative stress via p38 MAP kinase signaling involving type I radicals under sunlight/UVB exposure

Triclosan (TCS) is an antimicrobial preservative used in personal care products. Here, we have studied the phototoxicity, photogenotoxicity of TCS and its molecular mechanism involving p38 mitogen activated protein kinase (MAPK) pathway under UVB/sunlight exposure. We found that TCS showed photodegradation and photoproducts formation under UVB/sunlight. In silico study suggests that photosensitized TCS loses its preservative property due to the formation of its photoproducts. Photosensitized TCS induces significant O₂•-, •OH generation and lipid peroxidation via type-I photochemical reaction mechanism under UVB/sunlight exposure. We performed intracellular study of TCS on human skin keratinocytes (HaCaT cell-line) under the ambient intensity of UVB (0.6 mW/cm²) and sunlight exposure. Significant intracellular ROS generation was observed through DCFH2-DA/DHE assays along with a significant reduction in cell viability through MTT and NRU assays in photosensitized TCS. Photosensitized TCS also induces endoplasmic reticulum (ER) stress as shown through ER-tracker/DAPI staining and Ca²⁺ release. It further induced cell cycle arrest through the sub-G1 phase augmentation and caused lysosomal/mitochondrial destabilization. Photogenotoxicity was shown through significant tail DNA, micronuclei and cyclobutane pyrimidine dimers (CPDs) formations. Cell signaling mechanism implicated upregulated expression of cleaved Caspase-3, Bax, phospho-p38, phospho-JNK and cytochrome C, thereby downregulated Bcl-2 expressions. Results advocate that TCS induces phototoxic effects via type I mediated photodynamic mechanism and activation of MAPK pathway. We conclude that photoexcited TCS may be deleterious to human health at the ambient environmental intensities of sunlight reaching at the earth's surface. Therefore, it may be replaced by alternative safe preservative.

Fenton-reaction-stimulative nanoparticles decorated with a reactive-oxygen-species (ROS)-responsive molecular switch for ROS amplification and triple negative breast cancer therapy

P@P/H NPs were rapidly disintegrated in response to ROS, and this further enhanced ROS level in tumor cells via the Fenton reaction.

Prenatal exposure to benzophenone-3 (BP-3) induces apoptosis, disrupts estrogen receptor expression and alters the epigenetic status of mouse neurons

Current evidence indicates that benzophenone-3 (BP-3) can pass through the placental and blood-brain barriers and thus can likely affect infant neurodevelopment. Despite widespread exposure, data showing the effects of BP-3 on the developing nervous system are scarce. This study revealed for the first time that prenatal exposure to BP-3 led to apoptosis and neurotoxicity, altered the levels of estrogen receptors (ERs) and changed the epigenetic status of mouse neurons. In the present study, subcutaneous injections of pregnant mice with BP-3 at 50 mg/kg, which is an environmentally relevant dose, evoked activation of caspase-3 and lactate dehydrogenase (LDH) release as well as substantial loss of mitochondrial membrane potential in neocortical cells of their embryonic offspring. Apoptosis-focused microarray analysis of neocortical cells revealed up-regulation of 22 genes involved in apoptotic cell death. This effect was supported by increased BAX and CASP3 mRNA and protein levels, as evidenced by qPCR, ELISAs and western blots. BP-3-induced apoptosis and neurotoxicity were accompanied by decreases in the mRNA and protein expression levels of ESR1 and ESR2 (also known as ERα and ERβ), with a simultaneous increase in GPER1 (also known as GPR30) expression. In addition to the demonstration that treatment of pregnant mice with BP-3 induced apoptosis, caused neurotoxicity and altered ERs expression levels in neocortical cells of their embryonic offspring, we showed that prenatal administration of BP-3 inhibited global DNA methylation as well as reduced DNMTs activity. BP-3 also caused specific hypomethylation of the genes Gper1 and Bax, an effect that was accompanied by increased mRNA and protein expression levels. In addition, BP-3 caused hypermethylation of the genes Esr1, Esr2 and Bcl2, which could explain the reduced mRNA and protein levels of the estrogen receptors. This study demonstrated for the first time that prenatal exposure to BP-3 caused severe neuronal apoptosis that was accompanied by impaired ESR1/ESR2 expression, enhanced GPER1 expression, global DNA hypomethylation and altered methylation statuses of apoptosis-related and ERs genes. We suggest that the effects of BP-3 in embryonic neurons may be the fetal basis of the adult onset of nervous system disease.

Role of piwi-interacting RNA-651 in the carcinogenesis of non-small cell lung cancer

Piwi-interacting RNAs (piRNAs/piRs) are small non-coding RNAs that can serve important roles in genome stability by silencing transposable genetic elements. piR651, one of these novel piRNAs, regulates a number of biological functions, as well as carcinogenesis. Previous studies have reported that piR651 is overexpressed in human gastric cancer tissues and in several cancer cell lines, including non-small cell lung cancer (NSCLC) cell lines. However, the role of piRNAs in carcinogenesis has not been clearly defined. In the present study, a small interfering RNA inhibitor of piR651 was transfected into the NSCLC A549 and HCC827 cell lines to evaluate the effect of piR651 on cell growth. The association between piR651 expression and apoptosis was evaluated by flow cytometry and western blot analysis. Wound-healing and Transwell migration and invasion assays were used to determine the effect of piR651 on the migration and invasion of NSCLC cell lines. The results revealed that inhibition of piR651 inhibited cell proliferation and significantly increased the apoptotic rate compared with the negative control (NC), as well as altering the expression of apoptosis-associated proteins. There were fewer migrating and invading cells in the piR651-inhibited group than in the NC group in the Transwell assays. Furthermore, in the wound-healing assay, the wound remained wider in the piR651 inhibitor group, suggesting decreased cell migration compared with that in the NC group. The results of the present study demonstrate that piR651 potentially regulates NSCLC tumorigenic behavior by inhibiting cell proliferation, migration and invasion and by inducing apoptosis. Therefore, piR651 is a potential cancer diagnosis marker.

Association between SET expression and glioblastoma cell apoptosis and proliferation

Glioblastoma multiforme (GBM) was one of the first cancer types systematically studied at a genomic and transcriptomic level due to its high incidence and aggressivity; however, the detailed mechanism remains unclear, even though it is known that numerous cytokines are involved in the occurrence and development of GBM. The present study aimed to determine whether the SET gene has a role in human glioblastoma carcinogenesis. A total of 32 samples, including 18 cases of glioma, 2 cases of meningioma and 12 normal brain tissue samples, were detected using the streptavidin-peroxidase method through immunohistochemistry. To reduce SET gene expression in U251 and U87MG cell lines, the RNA interference technique was used and transfection with small interfering (si)RNA of the SET gene was performed. Cell apoptosis was detected by flow cytometry, cell migration was examined by Transwell migration assay and cell proliferation was determined by Cell Counting Kit-8. SET, Bcl-2, Bax and caspase-3 mRNA and protein expression levels were detected by reverse transcription-quantitative polymerase chain reaction and western blot analysis, respectively. Positive protein expression of SET was observed in the cell nucleus, with the expression level of SET significantly higher in glioma tissues compared with normal brain tissue (P=0.001). Elevated expression of SET was significantly associated with gender (P=0.002), tumors classified as World Health Organization grade II (P=0.031), III (P=0.003) or IV (P=0.001), and moderately (P=0.031) or poorly differentiated (P=0.001) tumors. Compared with the negative and non-treatment (blank) control cells, SET gene expression was significantly inhibited (P=0.006 and P<0.001), cell apoptosis was significantly increased (P=0.001 and P<0.001), cell proliferation was significantly inhibited (P=0.002 and P=0.015), and cell migration was significantly decreased (P=0.001 and P=0.001) in siRNA-transfected U87MG^−SET and U251^−SET cells, respectively. In addition, mRNA and protein expression levels of Bcl-2 were significantly inhibited in U87MG^−SET and U251^−SET cells, while mRNA and protein expression levels of Bax and caspase-3 were significantly increased, compared with the two control groups. Thus, the current data suggests that SET may regulate the proliferation and apoptosis of glioblastoma cells by upregulating Bcl-2, and downregulating Bax and caspase-3.

ROS mediated crosstalk between endoplasmic reticulum and mitochondria by Phloxine B under environmental UV irradiation

Phloxine B (PhB) is a most commonly used dye in cosmetic products throughout the world. It shows an absorption in visible and ultraviolet radiations. PhB was photodegraded within 4h of UV exposure. It generates reactive oxygen species (ROS) photochemically and intracellularly. Photosensitized PhB caused dose dependent cell viability reduction of human keratinocyte cell line (HaCaT) which was measured through MTT (75.4%) and NRU (77.3%) assays. It also induces cell cycle arrest and DNA damage. Photosensitized PhB induces Ca(2+) release from endoplasmic reticulum (ER). It causes the upregulation of ER stress marker genes ATF6 (1.79 fold) and CHOP (1.93 fold) at transcription levels. The similar response of ATF6 (3.6 fold) and CHOP (2.38 fold) proteins was recorded at translation levels. CHOP targeted the mitochondria and reduced the mitochondrial membrane potential analyzed through JC-1 staining. It further increases Bax/Bcl2 ratio (3.58 fold) and promotes the release of cytochrome c, finally leads to caspase-dependent apoptosis. Upregulation of APAF1 (1.79 fold) in PhB treated cells under UV B exposure supports the mitochondrial-mediated apoptotic cell death. The results support the involvement of ER and mitochondria in ROS mediated PhB phototoxicity. Therefore, the use of PhB in cosmetic products may be deleterious to users during sunlight exposure.

Effects of pentachlorophenol on the detoxification system in white-rumped munia (Lonchura striata)

Pentachlorophenol (PCP), a priority pollutant due to its persistence and high toxicity, has been used worldwide as a pesticide and biocide. To understand the adverse effects of PCP, adult male white-rumped munias (Lonchura striata) were orally administrated commercial PCP mixed with corn oil at dosages of 0, 0.05, 0.5, and 5mg/(kg·day) for 42day. Gas chromatography-mass spectrometry (GC-MS) analysis found that PCP was preferentially accumulated in the kidney rather than in the liver and muscle in all exposure groups. To examine the function of CYP1A in pollutant metabolism, we isolated two full-length cDNA fragments (designated as CYP1A4 and CYP1A5) from L. striata liver using reverse transcription-polymerase chain reaction and rapid amplification of cDNA ends. PCP induced the expression of CYP1A5, although no obvious change was observed in CYP1A4 expression. Furthermore, PCP significantly elevated the activities of ethoxyresorufin O-deethylase and methoxyresorufin O-demethylase and decreased the activity of benzyloxy-trifluoromethyl-coumarin, with no significant responses observed in benzyloxyresorufin O-debenzylase. PCP induced significant changes in antioxidant enzyme (superoxide dismutase and catalase) activities and malondialdehyde content, but decreased glutathione peroxidase (GSH-Px) and glutathione S-transferase activities and GSH content in the liver of L. striata. The present study demonstrated that PCP had hepatic toxic effects by affecting CYP1As and anti-oxidative status.

RETRACTED: Ambient UV-B exposure reduces the binding of ofloxacin with bacterial DNA gyrase and induces DNA damage mediated apoptosis

This article has been retracted: please see Elsevier Policy on Article Withdrawal (http://www.elsevier.com/locate/withdrawalpolicy). This article has been retracted at the request of the Editor-in-Chief. The study is retracted due to image duplication reasons: The article contains an image that had already appeared in Free Radic Res, 48.3 (2014): 333–346. DOI 10.3109/10715762.2013.869324. The images are used in both papers but to conclude something entirely different, and suggested that the images have an entirely different biological meaning and treatment. Duplicating images in this way is ethically not acceptable.

Benzophenone 1 induced photogenotoxicity and apoptosis via release of cytochrome c and Smac/DIABLO at environmental UV radiation

Solar UV radiation is main factor of photocarcinogenesis, photoageing, and phototoxicity; thus, protection from UV radiation is major concern. Sunscreens containing UV filters are suggested as sun safe practices, but safety of UV filters remains in controversies. Benzophenone-1 (BP1) is commonly used in sunscreens as UV blocker. We assessed the photogenotoxicity and apoptotic parameters in human keratinocytes (HaCaT cells) by western blot, immunocytochemistry, flowcytometry, comet assay and TEM imaging. Our results exposed that BP1 photosensitized and generated intracellular ROS (2.02 folds) under sunlight/UVR. Decrease in cell viability was recorded as 80.06%, 60.98% and 56.24% under sunlight, UVA and UVB, respectively. Genotoxic potential of BP1 was confirmed through photomicronuclei and CPDs formation. BP1 enhanced lipid peroxidation and leakage of LDH enzyme (61.7%). Apoptotic cells were detected by AnnexinV/PI staining and sub G1 population of cell cycle. BP1 induced up regulation of apoptotic proteins Bax/Bcl2 ratio, Apaf-1, cytochrome c, Smac/DIABLO and cleaved caspase 3 was noticed. Down regulation of pro caspase 3 was inhibited by Z-VAD-fmk (inhibitor of caspase). Thus, study established the involvement of BP1 in photogenotoxicity and apoptosis via release of cytochrome c and Smac/DIABLO. These findings suggest sunscreen user to avoid BP1 in cosmetics preparation for its topical application.