Effect of ultraviolet (UV) A, UVB or ionizing radiation on the cell cycle of human melanoma cells

Multicomponent synthesis and photophysical study of novel α,β-unsaturated carbonyl depsipeptides and peptoids

Multicomponent reactions were performed to develop novel α,β-unsaturated carbonyl depsipeptides and peptoids incorporating various chromophores such as cinnamic, coumarin, and quinolines. Thus, through the Passerini and Ugi multicomponent reactions (P-3CR and U-4CR), we obtained thirteen depsipeptides and peptoids in moderate to high yield following the established protocol and fundamentally varying the electron-rich carboxylic acid as reactants. UV/Vis spectroscopy was utilized to study the photophysical properties of the newly synthesized compounds. Differences between the carbonyl-substituted chromophores cause differences in electron delocalization that can be captured in the spectra. The near UV regions of all the compounds exhibited strong absorption bands. Compounds P2, P5, U2, U5, and U7 displayed absorption bands in the range of 250-350 nm, absorbing radiation in this broad region of the electromagnetic spectrum. A photostability study for U5 showed that its molecular structure does not change after exposure to UV radiation. Fluorescence analysis showed an incipient emission of U5, while U6 showed blue fluorescence under UV radiation. The photophysical properties and electronic structure were also determined by TD-DFT theoretical study.

In vitro and in vivo evaluation of 211At-labeled fibroblast activation protein inhibitor for glioma treatment

Glioma is the most common primary intracranial tumor without effective treatment. Positron emission tomography tracers labeled with 68Ga targeting fibroblast activation protein (FAP) have shown favorable characteristics in the diagnosis of glioma. However, to the best of our knowledge, FAP-targeted endoradiotherapy has never been explored in glioma. Hence, in this study, we investigated the therapeutic effect of 211At-labeled fibroblast activation protein inhibitor (FAPI) for glioma in vitro and in vivo. By astatodestannylation reaction, we prepared 211At-FAPI-04 with a radiochemical yield of 45 ± 6.7% and radiochemical purity of 98%. With good stability in vitro, 211At-FAPI-04 showed fast and specific binding to FAP-positive U87MG cells, and could significantly reduce the cell viability, arrested cell cycle at G2/M phase and suppressed cell proliferative efficacy. Biodistribution studies revealed that 6-fold higher accumulation in tumor sites was achieved by intratumoral injection in comparison with intravenous injection. In U87MG xenografts, 211At-FAPI-04 obviously suppressed the tumor growth and prolonged the median survival in a dose-dependent manner without obvious toxicity to normal organs. In addition, reduced proliferation and increased apoptosis were also observed after 211At-FAPI-04 treatment. All these results suggest that targeted alpha-particle therapy (TAT) mediated by 211At-FAPI-04 can provide an effective and promising strategy for the treatment of glioma.

Inhibition of Autophagy Enhances Curcumin United light irradiation-induced Oxidative Stress and Tumor Growth Suppression in Human Melanoma Cells

Malignant melanoma is the most aggressive form of skin carcinoma, which possesses fast propagating and highly invasive characteristics. Curcumin is a natural phenol compound that has various biological activities, such as anti-proliferative and apoptosis-accelerating impacts on tumor cells. Unfortunately, the therapeutical activities of Cur are severely hindered due to its extremely low bioavailability. In this study, a cooperative therapy of low concentration Cur combined with red united blue light irradiation was performed to inspect the synergistic effects on the apoptosis, proliferation and autophagy in human melanoma A375 cell. The results showed that red united blue light irradiation efficaciously synergized with Cur to trigger oxidative stress-mediated cell death, induce apoptosis and inhibit cell proliferation. Meanwhile, Western blotting revealed that combined disposure induced the formation of autophagosomes. Conversely, inhibition of the autophagy enhanced apoptosis, obstructed cell cycle arrest and induced reversible proliferation arrest to senescence. These findings suggest that Cur combined with red united blue light irradiation could generate photochemo-preventive effects via enhancing apoptosis and triggering autophagy, and pharmacological inhibition of autophagy convert reversible arrested cells to senescence, therefore reducing the possibility that damaged cells might escape programmed death.

A Potent Inhibitor of Phosphoinositide 3-Kinase (PI3K) and Mitogen Activated Protein (MAP) Kinase Signalling, Quercetin (3, 3', 4', 5, 7-Pentahydroxyflavone) Promotes Cell Death in Ultraviolet (UV)-B-Irradiated B16F10 Melanoma Cells

Ultraviolet (UV) radiation–induced skin damage contributes strongly to the formation of melanoma, a highly lethal form of skin cancer. Quercetin (Qu), the most widely consumed dietary bioflavonoid and well known inhibitor of phosphoinositide 3-kinase (PI3K) and mitogen activated protein (MAP) kinase signalling, has been reported to be chemopreventive in several forms of non-melanoma skin cancers. Here, we report that the treatment of ultraviolet (UV)-B-irradiated B16F10 melanoma cells with quercetin resulted in a dose dependent reduction in cell viability and increased apoptosis. The present study has brought out that the pro-apoptotic effects of quercetin in UVB-irradiated B16F10 cells are mediated through the elevation of intracellular reactive oxygen species (ROS) formation, calcium homeostasis imbalance, modulation of anti-oxidant defence response and depolarization of mitochondrial membrane potential (ΔΨ_M). Promotion of UVB-induced cell death by quercetin was further revealed by cleavage of chromosomal DNA, caspase activation, poly (ADP) ribose polymerase (PARP) cleavage, and an increase in sub-G1 cells. Quercetin markedly attenuated MEK-ERK signalling, influenced PI3K/Akt pathway, and potentially enhanced the UVB-induced NF-κB nuclear translocation. Furthermore, combined UVB and quercetin treatment decreased the ratio of Bcl-2 to that of Bax, and upregulated the expression of Bim and apoptosis inducing factor (AIF). Overall, these results suggest the possibility of using quercetin in combination with UVB as a possible treatment option for melanoma in future.

Photocarcinogenesis: an epidemiologic perspective on ultraviolet light and skin cancer

Photocarcinogenesis is the result of a complex interplay between ultraviolet radiation, DNA damage, mutation formation, DNA repair, apoptosis, and the immune system. Recent trends show an increase in incidence of both melanoma and nonmelanoma skin cancers. Some individuals have a genetic predisposition toward increased risk for skin cancer, whereas others experience increased risk through ultraviolet exposure and subsequent mutation formation. The initiation and propagation pathways of melanoma and nonmelanoma skin cancers differ but have some elements in common. The increase in incidence of skin cancer has been discovered to vary among age groups and gender.

Visible light is a better co-inducer of apoptosis for curcumin-treated human melanoma cells than UVA

Curcumin attracts worldwide scientific interest due to its anti-proliferative and apoptosis inducing effects on different tumor cells at concentrations ranging from 10 to 150 µM (3.7-55 µg/ml). Unfortunately, because of a low oral bioavailability, only low and pharmacologically ineffective serum levels are achievable. In this study, an alternative treatment concept consisting of low concentration curcumin (0.2-5 µg/ml) and irradiation with UVA or visible light (VL) has been tested. The experimental results show clearly that this treatment decreases the proliferation and the viability of human melanoma cells while the cell membrane integrity remains intact. We identified the onset of apoptosis characterized by typical markers such as active caspases 8, 9 and 3 as well as DNA fragmentation accompanied by the loss of cell adhesion. The mitochondrial apoptosis signaling pathway is predominant due to an early activation of caspase-9. The present data indicate a higher efficacy of a combination of curcumin and VL than curcumin and UVA. Reduced effects as a result of light absorption by heavily pigmented skin are unlikely if VL is used. These results indicate that a combination of curcumin and light irradiation may be a useful additional therapy in the treatment of malignant disease.

Serotonin and ionizing radiation synergistically affect proliferation and adhesion molecule expression of malignant melanoma cells

BACKGROUND

Mast cells are key effectors of the immune system and are involved in a variety of physiological and pathophysiological processes. Dermal mast cells have been demonstrated to degranulate as a consequence of ionizing radiation exposure. Mast cells accumulate at the periphery of skin tumours including malignant melanoma. Melanoma cells thus represent a potential target for the action of mediators released from irradiated mast cells.

OBJECTIVE

In this study, we evaluated the effects of serotonin and ionizing radiation on the proliferation and the adhesion molecule expression of malignant melanoma cells.

METHODS

Human mast cells (HMC-1) were examined for serotonin release after irradiation using an enzyme-linked immunosorbent assay (ELISA). Protein expression of serotonin receptors and adhesion molecules on human melanoma cells (IPC-298) was investigated by flow cytometry. Cell attachment to fibronectin was determined by an adhesion assay. Proliferation and cell cycle kinetics were analysed by proliferation assay and 5-bromodeoxyuridine (BrdU)/DNA dual parameter flow cytometry, respectively.

RESULTS

Ionizing radiation exposure resulted in serotonin release by HMC-1 cells. Expression of serotonin receptors was detected on IPC-298 cells. Serotonin enhanced the radiation-induced reduction in melanoma cell proliferation. Serotonin and ionizing radiation synergistically increased the expression of adhesion molecules on melanoma cells and improved cell adhesion to fibronectin. The up-regulation of cellular adhesion molecule expression was attenuated by inhibitors to phosphatidylinositol 3-kinase, mitogen-activated protein (MAP) ERK kinase and protein kinase C.

CONCLUSIONS

Our data suggest that serotonin released from irradiated dermal mast cells modulates the radiation response of human melanoma cells. We postulate that radiation-induced mast cell degranulation and mediator release have a great impact on malignant melanoma cell development.

MiTF links Erk1/2 kinase and p21 CIP1/WAF1 activation after UVC radiation in normal human melanocytes and melanoma cells

As a survival factor for melanocytes lineage cells, MiTF plays multiple roles in development and melanomagenesis. What role MiTF plays in the DNA damage response is currently unknown. In this report we observed that MiTF was phosphorylated at serine 73 after UVC radiation, which was followed by proteasome-mediated degradation. Unlike after c-Kit stimulation, inhibiting p90RSK-1 did not abolish the band shift of MiTF protein, nor did it abolish the UVC-mediated MiTF degradation, suggesting that phosphorylation on serine 73 by Erk1/2 is a key event after UVC. Furthermore, the MiTF-S73A mutant (Serine 73 changed to Alanine via site-directed mutagenesis) was unable to degrade and was continuously expressed after UVC exposure. Compared to A375 melanoma cells expressing wild-type MiTF (MiTF-WT), cells expressing MiTF-S73A mutant showed less p21^WAF1/CIP1 accumulation and a delayed p21^WAF1/CIP1 recovery after UVC. Consequently, cells expressing MiTF-WT showed a temporary G1 arrest after UVC, but cells expressing MiTF-S73A mutant or lack of MiTF expression did not. Finally, cell lines with high levels of MiTF expression showed higher resistance to UVC-induced cell death than those with low-level MiTF. These data suggest that MiTF mediates a survival signal linking Erk1/2 activation and p21^WAF1/CIP1 regulation via phosphorylation on serine 73, which facilitates cell cycle arrest. In addition, our data also showed that exposure to different wavelengths of UV light elicited different signal pathways involving MiTF.

Apoptotic DNA fragmentation can be revealed in situ: an ultrastructural approach

A common pattern of apoptotic death is DNA cleavage, initially producing large fragments (50 kbp), followed by the production of nucleosomic/oligonucleosomic fragments. Nevertheless, apoptosis without DNA fragmentation, at least of the nucleosomic type, has been reported. To investigate the spatial relationship between DNA cleavage and chromatin condensation, we applied the TUNEL technique to the ultrastructural analysis of apoptotic cells. A modified method, utilizing a gold-conjugated antidigoxigenin antibody, was carried out on U937 versus Molt-4 cells, both exposed to UVB radiation or staurosporine treatment. Gold particle density in the different domains of apoptotic cells was evaluated by a four-way ANOVA test. Gold labelling was more strongly localised in condensed chromatin than in the diffuse chromatin. U937 cells, which evidenced in vitro oligonucleosomic fragmentation after both UVB and staurosporine treatments, revealed a significantly higher gold particle density, when compared with Molt-4, which did not show, on the other hand, oligonucleosomic cleavage even in the presence of < or = 50 kbp cleavage. Thus, a correlation between DNA fragment sizes and gold particle density appears. TUNEL applied to electron microscopy is an effective approach to study the relationship between apoptotic chromatin condensation and DNA cleavage. Both these events indeed appear in the apoptotic nucleus, but their reciprocal correlation is still greatly unknown. Microsc. Res. Tech. 2009. (c) 2009 Wiley-Liss, Inc.

Discrimination analysis of human lung cancer cells associated with histological type and malignancy using Raman spectroscopy

The Raman spectroscopic technique enables the observation of intracellular molecules without fixation or labeling procedures in situ. Raman spectroscopy is a promising technology for diagnosing cancers-especially lung cancer, one of the most common cancers in humans-and other diseases. The purpose of this study was to find an effective marker for the identification of cancer cells and their malignancy using Raman spectroscopy. We demonstrate a classification of cultured human lung cancer cells using Raman spectroscopy, principal component analysis (PCA), and linear discrimination analysis (LDA). Raman spectra of single, normal lung cells, along with four cancer cells with different pathological types, were successfully obtained with an excitation laser at 532 nm. The strong appearance of bands due to cytochrome c (cyt-c) indicates that spectra are resonant and enhanced via the Q-band near 550 nm with excitation light. The PCA loading plot suggests a large contribution of cyt-c in discriminating normal cells from cancer cells. The PCA results reflect the nature of the original cancer, such as its histological type and malignancy. The five cells were successfully discriminated by the LDA.

Cellular and sub-cellular responses to UVA in relation to carcinogenesis

PURPOSE

UVA radiation (315-400 nm) contributes to skin aging and carcinogenesis. The aim of this review is to consider the mechanisms that underlie UVA-induced cellular damage, how this damage may be prevented or repaired and the signal transduction processes that are elicited in response to it.

RESULTS

Exposure to ultraviolet (UV) light is well-established as the causative factor in skin cancer. Until recently, most work on the mechanisms that underlie skin carcinogenesis focused on shorter wavelength UVB radiation (280-315 nm), however in recent years there has been increased interest in the contribution made by UVA. UVA is able to cause a range of damage to cellular biomolecules including lipid peroxidation, oxidized protein and DNA damage, such as 8-oxoguanine and cyclobutane pyrimidine dimers. Such damage is strongly implicated in both cell death and malignant transformation and cells have a number of mechanisms in place to mitigate the effects of UVA exposure, including antioxidants, DNA repair, and stress signalling pathways.

CONCLUSIONS

The past decade has seen a surge of interest in the biological effects of UVA exposure as its significance to the process of photo-carcinogenesis has become increasingly evident. However, unpicking the unique complexity of the cellular response to UVA, which is only now becoming apparent, will be a major challenge for the field of photobiology in the 21st century.

Melanosomal damage in normal human melanocytes induced by UVB and metal uptake--a basis for the pro-oxidant state of melanoma

Melanins are ubiquitous catecholic pigments, formed in organelles called melanosomes within melanocytes, the function of which is to protect skin against harmful effects of UV radiation. Melanosomes within melanoma cells are characteristically abnormal, with fragmented melanin and disrupted membranes. We hypothesize that the disruption of melanosomal melanin might be an early event in the etiology and progression of melanoma, leading to increased oxidative stress and mutation. In this report, we examine the effect of a combination of UV treatment and metal ion exposure on melanosomes within melanocytes, as well as their ability to act as pro-oxidants in ex situ experiments, and assay the effects of this treatment on viability and cell cycle progression. UVB exposure causes morphologic changes of the cells and bleaching of melanosomes in normal melanocytes, both significantly enhanced in Cu(II) and Cd(II)-treated cells, as observed by microscopy. The promoted bleaching by Cu(II) is due to its ability to redox cycle under oxidative conditions, generating reactive oxygen species; verified by the observed enhancement of hydroxyl radical generation when isolated melanosomes were treated with both Cu(II) ions and UVB, as assayed by DNA clipping. Single-dose UVB/Cu treatment does not greatly affect cell viability or cell cycle progression in heavily pigmented cells, but did so in an amelanotic early stage melanoma cell line.

Anti-apoptotic role of S100A8 in X-ray irradiated keratinocytes

BACKGROUND

Ionizing radiation is used to treat a lot of cancers, however, it also produced unwanted side effect on normal tissues, such as radiodermatitis. We previously established an animal model for radiodermatitis, and identified many of radiation-induced genes by cDNA microarray. Of the candidates, we chose S100A8 gene for a further study.

OBJECTIVE

The aim of this study is to investigate the functional role of S100A8 in X-ray irradiated keratinocytes.

METHODS

RT-PCR and immunohistochemistry were performed to demonstrate the S100A8 induction by X-ray irradiation. HaCaT keratinocytes were transduced with the recombinant adenovirus expressing GFP-S100A8, and then effects on cell cycle and apoptosis were analyzed using flow cytometry and Western blot.

RESULTS

X-ray irradiation markedly induced S100A8 expression in the hyperplastic epidermis of mouse. Overexpression of S100A8 by adenoviral transduction led to the enhancement of cell proliferation in the absence and/or presence of X-ray irradiation, as compared with Ad/GFP control group. Furthermore, overexpression of S100A8 significantly protected the X-ray-induced apoptosis.

CONCLUSION

These results suggest that S100A8 have an anti-apoptotic role in X-ray irradiated keratinocytes.