Effect of blue light emitting diodes on melanoma cells: Involvement of apoptotic signaling

Antiviral and synergistic effects of photo-energy with acyclovir on herpes simplex virus type 1 infection

This experimental study aimed to evaluate the antiviral and synergistic effects of photoenergy irradiation on human herpes simplex virus type I (HSV-1) infection. We assessed viral replication, plaque formation, and relevant viral gene expression to examine the antiviral and synergistic effects of blue light (BL) with acyclovir treatment. Our results showed that daily BL (10 J/cm2) irradiation inhibited plaque-forming ability and decreased viral copy numbers in HSV-1-infected monkey kidney epithelial Vero cells and primary human oral keratinocyte (HOK) cells. Combined treatment with the antiviral agent acyclovir and BL irradiation increased anti-viral activity, reducing viral titers and copy numbers. In particular, accumulated BL irradiation suppressed characteristic viral genes including UL19 and US6, and viral DNA replication-essential genes including UL9, UL30, UL42, and UL52 in HOK cells. Our results suggest that BL irradiation has anti-viral and synergistic properties, making it a promising therapeutic candidate for suppressing viral infections in clinical trials.

Blue light irradiation inhibits the M2 polarization of the cancer-associated macrophages in colon cancer

Recent studies have shown that blue light-emitting diode (LED) light has anti-tumor effects, suggesting the possibility of using visible light in cancer therapy. However, the effects of blue light irradiation on cells in the tumor microenvironment, including tumor-associated macrophages (TAMs), are unknown. Here, THP-1 cells were cultured in the conditioned medium (CM) of HCT-116 cells to prepare TAMs. TAMs were divided into LED-irradiated and control groups. Then, the effects of blue LED irradiation on TAM activation were examined. Expression levels of M2 macrophage markers CD163 and CD206 expression were significantly decreased in LED-irradiated TAMs compared with the control group. While control TAM-CM could induce HCT-116 cell migration, these effects were not observed in cells cultured in TAM-CM with LED irradiation. Vascular endothelial growth factor (VEGF) secretion was significantly suppressed in LED-exposed TAMs. PD-L1 expression was upregulated in HCT-116 cells cultured with TAM-CM but attenuated in cells cultured with LED-irradiated TAM-CM. In an in vivo model, protein expression levels of F4/80 and CD163, which are TAM markers, were reduced in the LED-exposed group. These results indicate that blue LED light may have an inhibitory effect on TAMs, as well as anti-tumor effects on colon cancer cells.

Exposure of Bladder Cancer Cells to Blue Light (λ = 453 nm) in the Presence of Riboflavin Synergistically Enhances the Cytotoxic Efficiency of Gemcitabine

Non-muscle invasive bladder cancer is a common tumour in men and women. In case of resistance to the standard therapeutic agents, gemcitabine can be used as off-label instillation therapy into the bladder. To reduce potential side effects, continuous efforts are made to optimise the therapeutic potential of drugs, thereby reducing the effective dose and consequently the pharmacological burden of the medication. We recently demonstrated that it is possible to significantly increase the therapeutic efficacy of mitomycin C against a bladder carcinoma cell line by exposure to non-toxic doses of blue light (453 nm). In the present study, we investigated whether the therapeutically supportive effect of blue light can be further enhanced by the additional use of the wavelength-specific photosensitiser riboflavin. We found that the gemcitabine-induced cytotoxicity of bladder cancer cell lines (BFTC-905, SW-1710, RT-112) was significantly enhanced by non-toxic doses of blue light in the presence of riboflavin. Enhanced cytotoxicity correlated with decreased levels of mitochondrial ATP synthesis and increased lipid peroxidation was most likely the result of increased oxidative stress. Due to these properties, blue light in combination with riboflavin could represent an effective therapy option with few side effects and increase the success of local treatment of bladder cancer, whereby the dose of the chemotherapeutic agent used and thus the chemical load could be significantly reduced with similar or improved therapeutic success.

Exploring the Potential of Montmorillonite as an Antiproliferative Nanoagent against MDA-MB-231 and MCF-7 Human Breast Cancer Cells

Unlike MCF-7 cells, MDA-MB-231 cells are unresponsive to hormone therapy and often show resistance to chemotherapy and radiotherapy. Here, the antiproliferative effect of biocompatible montmorillonite (Mt) nanosheets on MDA-MB-231 and MCF-7 human breast cancer cells was evaluated by MTT assay, flow cytometry, and qRT-PCR. The results showed that the Mt IC50 for MDA-MB-231 and MCF-7 cells in a fetal bovine serum (FBS)-free medium was ~50 and ~200 µg/mL, and in 10% FBS medium ~400 and ~2000 µg/mL, respectively. Mt caused apoptosis in both cells by regulating related genes including Cas-3, P53, and P62 in MDA-MB-231 cells and Bcl-2, Cas-8, Cas-9, P53, and P62 in MCF-7 cells. Also, Mt arrested MCF-7 cells in the G0/G1 phase by altering Cyclin-D1 and P21 expression, and caused sub-G1 arrest and necrosis in both cells, possibly through damaging the mitochondria. However, fewer gene expression changes and more sub-G1 arrest and necrosis were observed in MDA-MB-231 cells, confirming the higher vulnerability of MDA-MB-231 cells to Mt. Furthermore, MDA-MB-231 cells appeared to be much more vulnerable to Mt compared to other cell types, including normal lung fibroblast (MRC-5), colon cancer (HT-29), and liver cancer (HepG2) cells. The higher vulnerability of MDA-MB-231 cells to Mt was inferred to be due to their higher proliferation rate. Notably, Mt cytotoxicity was highly dependent on both the Mt concentration and serum level, which favors Mt for the local treatment of MDA-MB-231 cells. Based on these results, Mt can be considered as an antiproliferative nanoagent against MDA-MB-231 cells and may be useful in the development of local nanoparticle-based therapies.

Photobiomodulation effects of blue light on osteogenesis are induced by reactive oxygen species

Blue light-mediated photobiomodulation (PBM) is a promising approach to promote osteogenesis. However, the underlying mechanisms of PBM in osteogenesis are poorly understood. In this study, a human osteosarcoma cell line (i.e., Saos-2 cells) was subjected to intermittent blue light exposure (2500 µM/m2/s, 70 mW/cm2, 4.2 J/cm2, once every 48 h) and the effects on Saos-2 cell viability, metabolic activity, differentiation, and mineralization were investigated. In addition, this study addressed a possible role of blue light induced cellular oxidative stress as a mechanism for enhanced osteoblast differentiation and mineralization. Results showed that Saos-2 cell viability and metabolic activity were maintained upon blue light exposure compared to unilluminated controls, indicating no negative effects. To the contrary, blue light exposure significantly increased (p < 0.05) alkaline phosphatase activity and Saos-2 cell mediated mineralization. High-performance liquid chromatography (HPLC) assay was used for measurement of reactive oxygen species (ROS) activity and showed a significant increase (p < 0.05) in superoxide (O2•-) and hydrogen peroxide (H2O2) formed after blue light exposure. Together, these results suggest that the beneficial effects of blue light-mediated PBM on osteogenesis may be induced by controlled release of ROS.

Blue light photobiomodulation induced apoptosis by increasing ROS level and regulating SOCS3 and PTEN/PI3K/AKT pathway in osteosarcoma cells

Blue light photobiomodulation (PBM) has attracted great attention in diminishing proliferation and inducing death of cancer cells recently. Osteosarcoma (OS) primarily occurring in children and adolescents, the limitations of drug resistance and limb salvage make it urgent to develop and identify new adjuvant therapeutic strategies. In this work, we attempted to research the anticancer effects and biological mechanisms of blue light PBM in human OS MG63 cells. The effects of various blue light parameters on MG63 cells indicated that suppressed cell proliferation and cell migration, induced cell apoptosis which are experimentally assessed using multiple assays including CCK, LDH, wound healing assay and Hoechst staining. Concurrently, the increases of ROS level and the inhibition of PI3K and AKT expression were identified under high-dose blue light PBM in MG63 cells. Meanwhile, SOCS3 is a major inducible anti-tumor molecule, we also found that blue light LED substantially promoted its expression. Thus, this study proposed that bule light PBM may be a hopeful therapeutic approach in OS clinical treatment in the future.

Blue Light Inhibits Proliferation of Metastatic Cancer Cells by Regulating Translational Initiation: A Synergistic Property with Anticancer Drugs

The aim of this study was to examine the inhibitory effect of blue light (BL) on the proliferation of metastatic cancer cells and synergistic properties with chemo-drugs. BL significantly inhibited the proliferation of B cell lymphoma (A20 and RAMOS) cells in a dose-dependent manner. Anti-proliferative effect of BL irradiation was identified to be associated with the inhibition of proliferating-cell nuclear antigen expression and cell cycle by decreasing S-phase cells. Consistent with its inhibitory effects, BL irradiation at 20 J/cm2 daily for 10 days inhibited metastasis of cancer cells which were distributed and invaded to other organs including bone marrow, liver, kidney, etc., and induced paraplegia, thereby leading to an increased survival rate of tumor-bearing mice. Anti-proliferative activity of BL was expanded in solid tumor cells including pancreatic carcinoma (Mia PaCa-2, PANC-1), lung carcinoma A549 and colorectal carcinoma HCT116 cells. Additionally, combination with chemo-drugs such as 5-FU and gemcitabine resulted in an increase in the anti-proliferative activity after BL irradiation accompanied by regulating mRNA translational process via inhibition of p70S6K, 4EBP-1 and eIF4E phosphorylation during cellular proliferation. These results indicate the anti-metastatic and photo-biogoverning abilities of BL irradiation as a potent therapeutic potential for repressing the progression of tumor cells.

Tocotrienol-Rich Fraction Attenuates Blue Light-Induced Oxidative Stress and Melanogenesis in B16-F1 Melanocytes via Anti-Oxidative and Anti-Tyrosinase Properties

Our skin is constantly exposed to blue light (BL), which is abundant in sunlight and emitted by digital devices. Prolonged exposure to BL can lead to oxidative stress-induced damages and skin hyperpigmentation. For this study, we used a cell line-based model to examine the protective effects of tocotrienol-rich fraction (TRF) on BL-induced oxidative stress and hyperpigmentation in B16-F1 melanocytes. Alpha-tocopherol (αTP) was used as a comparator. Molecular assays such as cell viability assay, flow cytometry, western blotting, fluorescence imaging, melanin and tyrosinase analysis were performed. Our results showed that TRF effectively suppressed the formation of reactive oxygen species and preserved the mitochondrial membrane potential. Additionally, TRF exhibited anti-apoptotic properties by reducing the activation of the p38 mitogen-activated protein kinase molecule and downregulating the expression of cleaved caspase-3. Moreover, TRF modulated tyrosinase activity, resulting in a lowered rate of melanogenesis and reduced melanin production. In contrast, αTP did not exhibit significant protective effects against skin damages and pigmentation in BL-induced B16-F1 cells. Therefore, this study indicates that TRF may offer superior protective effects over αTP against the effects of BL on melanocytes. These findings demonstrate the potential of TRF as a protective natural ingredient that acts against BL-induced skin damages and hyperpigmentation via its anti-oxidative and anti-melanogenic properties.

Proliferation inhibition and apoptosis of liver cancer cells treated by blue light irradiation

Blue light (BL) irradiation has been a potentially efficient treatment for many kinds of tumors. In this study, a BL irradiation (centered at 453 nm in wavelength) was proposed to treat the common human liver cancer cell lines of SMMC-7721 and HepG2, examined by means of flow cytometry, western blot, fluorescence microscope assay. In comparison to control groups, the apoptosis and proliferation inhibition of both BL-treated cells are expressively enhanced by mitochondrial apoptosis. The mechanism of apoptosis is related to the more production of reactive oxygen species (ROS) induced by BL and the corresponding changes in the expression of apoptosis-related Bcl-2, Bax and Bad proteins. In addition, the migration rate of the cancer cells could be reduced after BL irradiation. These results demonstrate that introducing BL irradiation is helpful to establish an effective and low toxicity strategy for the clinical treatment of liver tumors.

Blue light irradiation exerts anti-viral and anti-inflammatory properties against herpes simplex virus type 1 infection

The aim of this study was to investigate the antiviral and anti-inflammatory functions of blue light (BL) in cutaneous viral infections. Previously, we examined the photo-biogoverning role of 450 nm BL in SARS-CoV-2-infected cells, which showed that photo-energy could inhibit viral activation depending on the number of photons. However, the communication network between photo-energy irradiation and immune cells involved in viral infections has not been clarified. We verified viral activation, inflammatory responses, and relevant downstream cascades caused by human simplex virus type I (HSV-1) after BL irradiation. To examine the antiviral effect of BL, we further tested whether BL could disturb viral absorption or entry into host cells. The results showed that BL irradiation, but not green light (GL) exposure, specifically decreased plaque-forming activity and viral copy numbers in HSV-1-infected cells. Accumulated BL irradiation inhibited the localization of viral proteins and the RNA expression of characteristic viral genes such as UL19, UL27, and US6, thus exerting to an anti-viral effect. The results also showed that BL exposure during viral absorption interfered with viral entry or destroyed the virus, as assessed by plaque formation and quantitative PCR assays. The levels of the pro-inflammatory mediators interleukin (IL)-18 and IL-1β in M1-polarized macrophages were increased by HSV-1 infection. However, these increases were attenuated by BL irradiation. Importantly, BL irradiation decreased cGAS and STING expression, as well as downstream NF-κB p65, in M1-polarized HSV-1-infected macrophages, demonstrating anti-viral and anti-inflammatory properties. These findings suggest that BL could serve as an anti-viral and anti-inflammatory therapeutic candidate to treat HSV-1 infections.

Progress of phototherapy for osteosarcoma and application prospect of blue light photobiomodulation therapy

Osteosarcoma (OS) is the most common primary malignant bone tumor that mainly affects the pediatric and adolescent population; limb salvage treatment has become one of the most concerned and expected outcomes of OS patients recently. Phototherapy (PT), as a novel, non-invasive, and efficient antitumor therapeutic approach including photodynamic therapy (PDT), photothermal therapy (PTT), and photobiomodulation therapy (PBMT), has been widely applied in superficial skin tumor research and clinical treatment. OS is the typical deep tumor, and its phototherapy research faces great limitations and challenges. Surprisingly, pulse mode LED light can effectively improve tissue penetration and reduce skin damage caused by high light intensity and has great application potential in deep tumor research. In this review, we discussed the research progress and related molecular mechanisms of phototherapy in the treatment of OS, mainly summarized the status quo of blue light PBMT in the scientific research and clinical applications of tumor treatment, and outlooked the application prospect of pulsed blue LED light in the treatment of OS, so as to further improve clinical survival rate and prognosis of OS treatment and explore corresponding cellular mechanisms.

Potent Chlorambucil-Platinum(IV) Prodrugs

The DNA-alkylating derivative chlorambucil was coordinated in the axial position to atypical cytotoxic, heterocyclic, and non-DNA coordinating platinum(IV) complexes of type, [Pt^IV(H_L)(A_L)(OH)₂](NO₃)₂ (where H_L is 1,10-phenanthroline, 5-methyl-1,10-phenanthroline or 5,6-dimethyl-1,10-phenanthroline, A_L is 1S,2S-diaminocyclohexane). The resultant platinum(IV)-chlorambucil prodrugs, PCLB, 5CLB, and 56CLB, were characterized using high-performance liquid chromatography, nuclear magnetic resonance, ultraviolet-visible, circular dichroism spectroscopy, and electrospray ionization mass spectrometry. The prodrugs displayed remarkable antitumor potential across multiple human cancer cell lines compared to chlorambucil, cisplatin, oxaliplatin, and carboplatin, as well as their platinum(II) precursors, PHENSS, 5MESS, and 56MESS. Notably, 56CLB was exceptionally potent in HT29 colon, Du145 prostate, MCF10A breast, MIA pancreas, H460 lung, A2780, and ADDP ovarian cell lines, with GI₅₀ values ranging between 2.7 and 21 nM. Moreover, significant production of reactive oxygen species was detected in HT29 cells after treatment with PCLB, 5CLB, and 56CLB up to 72 h compared to chlorambucil and the platinum(II) and (IV) precursors.

Red Light Phototherapy Using Light-Emitting Diodes Inhibits Melanoma Proliferation and Alters Tumor Microenvironments

Background

Total annual cancer rates have decreased due to improved treatment and prevention. However, the incidence of melanoma is rising, and not all patients respond to immune and targeted approaches. Therefore, we sought to determine the efficacy of red light (RL) phototherapy in preclinical models of melanoma.

Methods

Melanoma cells (A375, B16F10, MNT-1) were irradiated with RL. Melanoma proliferation, apoptosis, oxidative stress, and p53 phosphorylation were measured in vitro. In C57BL/6 mice, phototherapy safety, B16F10 tumor growth, and immunocyte infiltration were assessed following RL.

Results

In vitro, 640 J/cm² RL decreased cellular proliferation without increasing apoptosis, while 1280 J/cm² increased apoptosis. RL increased intracellular reactive oxygen species generation and p53 phosphorylation. In animal models, 2560 J/cm² RL significantly prevented melanoma growth and increased the expression of CD103+ dendritic cells. 1280 and 1920 J/cm² RL decreased tumor volume, but not significantly. RL did not cause skin inflammation or erythema in normal skin.

Conclusion

RL represents a potentially safe and effective melanoma therapeutic. RL prevented tumor growth and increased the expression of immune markers, such as CD103, that are associated with favorable melanoma outcomes. Further research is needed to determine the optimal clinical treatment regimen for melanoma using RL.

Blue light irradiation inhibits the growth of colon cancer and activation of cancer‑associated fibroblasts

Irradiation with a specific wavelength of light using light‑emitting diodes (LEDs) has various effects on cells and organisms. Recently, the antitumor effects of visible blue light on tumor cells were reported; however, the mechanism and effects on the tumor microenvironment remain unclear. Human colon cancer cells (HCT‑116) were injected into the rectal wall of nude mice. Tumors were irradiated with a 465‑nm LED light at 30 mW/cm² for 30 min. Tumor volumes and the expression levels of opsin 3 (Opn3), autophagy‑related factors, cancer‑associated fibroblast (CAF) markers, and programmed cell death 1‑ligand (PD‑L1) were measured. Additionally, human intestinal fibroblasts were cultured in HCT116‑conditioned medium (CM) to prepare CAFs. CAFs were divided into an LED group and a control group, and the effect of the LED light on CAF activation in colon cancer cells was examined. Irradiation with blue LED light suppressed tumor growth; Opn3 expression was localized to the cell membrane in the LED group. Irradiated tumors exhibited increased autophagy‑related gene expression. Furthermore, in the LED group, TGF‑β and α‑SMA expression levels in the fibroblasts were decreased. Regarding CAFs, α‑SMA and IL‑6 expression levels were decreased in the LED group. HCT‑116 cells cultured in CAF‑CM with LED irradiation showed no enhanced migration or invasion. In the HCT‑116 cells cultured in CM of CAFs irradiated with LED, the relative increase in PD‑L1 expression was lower than that noted in the CAF‑CM without LED irradiation. Blue LED light may have a direct antitumor effect on colon cancer and also an inhibitory effect on CAFs.

Localised light delivery on melanoma cells using optical microneedles

Light-based therapy is an emerging treatment for skin cancer, which has received increased attention due to its drug-free and non-invasive approach. However, the limitation of current light therapy methods is the inability for light to penetrate the skin and reach deep lesions. As such, we have developed a polylactic acid (PLA) microneedles array as a novel light transmission platform to perform in vitro evaluation regarding the effect of light therapy on skin cancer. For the first time, we designed and fabricated a microneedle array system with a height fixation device that can be installed in a cell culture dish and an LED array for blue light irradiation. The effect of the blue light combined with the microneedles on cell apoptosis was evaluated using B16F10 melanoma cells and analyzed by Hoechst staining. Our results demonstrate that blue light can be transmitted by microneedles to skin cells and effectively affect cell viability.

Drug-free phototherapy of superficial tumors: White light at the end of the tunnel

Visible light has long been recognized as a treatment for many diseases and an essential component of photo-induced chemotherapy. While previous data proved its inherent cytotoxicity, this study is the first to explore the use of a commercially available, high-intensity white LED light (24.5 mW.cm^-2) as a treatment for skin tumors. After a 9-h exposure in vitro, the viability of Human Malignant Melanoma cells (A375) decreased by around 70%. Western blot analysis suggested an apoptotic cell death confirmed by the upregulation of Bax, cleaved PARP/caspase-3/8, cytochrome c, and t-bid. Additionally, cellular ROS accumulation and DNA damage were induced upon irradiation with blue light. When tested on a DMBA/TPA skin carcinogenesis model, a 90-min exposure to white light thrice weekly resulted in a significant decrease in tumor volumes/incidence compared to control and cisplatin groups, and restored normal morphological features, as confirmed by histopathology. Toxicological evaluation of ight-treated animals indicated a 100% survival rate, no skin irritation, no signs of discomfort or changes in body weight/behavior, and no toxicities to vital organs. Although these results must be confirmed by further studies, this research showed that short-exposure by commercially available high-intensity white LED light irradiation may be a promising approach for the treatment of superficial malignancies.

Evaluation of Photobiogoverning Role of Blue Light Irradiation on Viral Replication

Most recently, severe acute respiratory syndrome coronavirus-2 has triggered a global pandemic without successful therapeutics. The goal of the present study was to define the antiviral effect and therapeutic action of blue light irradiation in SARS-CoV-2-infected cells. Vero cells were infected with SARS-CoV-2 (NCCP43326) or mock inoculum at 50 pfu/well. After blue light irradiation, the inhibitory effect was assessed by qPCR and plaque reduction assay. When Vero cells were irradiated to blue light ranging from 1.6 to 10 J cm^-2 , SARS-CoV-2 replication was inhibited by up to 80%. The antiviral effect of blue light irradiation was associated with translation suppression via the phosphorylation of eIF2α by prolonging endoplasmic reticulum (ER) stress. The levels of LC3A/B and Beclin-1, which are key markers of autophagy, and the levels of PERK and PDI for ER stress were highly increased, whereas caspase-3 cleavage was inhibited after blue light irradiation in the later stage of infection. Our data revealed that blue light irradiation exerted antiviral and photo-biogoverning activities by prolonging ER stress and stimulating autophagy progression during viral infection. The findings increase our understanding of how photo-energy acts on viral progression and have implications for use in therapeutic strategies against COVID-19.

Controlled killing of human cervical cancer cells by combined action of blue light and C-doped TiO2 nanoparticles

In this study, C-doped TiO₂ nanoparticles (C-TiO₂) were prepared and tested as a photosensitizer for visible-light-driven photodynamic therapy against cervical cancer cells (HeLa). X-ray diffraction and Transmission Electron Microscopy confirmed the anatase form of nanoparticles, spherical shape, and size distribution from 5 to 15 nm. Ultraviolet-visible light spectroscopy showed that C doping of TiO₂ enhances the optical absorption in the visible light range caused by a bandgap narrowing. The photo-cytotoxic activity of C-TiO₂ was investigated in vitro against HeLa cells. The lack of dark cytotoxicity indicates good biocompatibility of C-TiO₂. In contrast, a combination with blue light significantly reduced the survival of HeLa cells: illumination only decreased cell viability by 30% (15 min of illumination, 120 µW power), and 60% when HeLa cells were preincubated with C-TiO₂. We have also confirmed blue light-induced C-TiO₂-catalyzed generation of reactive oxygen species in vitro and intracellularly. Oxidative stress triggered by C-TiO₂/blue light was the leading cause of HeLa cell death. Fluorescent labeling of treated HeLa cells showed distinct morphological changes after the C-TiO₂/blue light treatment. Unlike blue light illumination, which caused the appearance of large necrotic cells with deformed nuclei, cytoplasm swelling, and membrane blebbing, a combination of C-TiO₂/blue light leads to controlled cell death, thus providing a better outcome of local anticancer therapy.

The review of the light parameters and mechanisms of Photobiomodulation on melanoma cells

Photobiomodulation (PBM) uses low-intensity visible or near-infrared light to produce beneficial effects on cells or tissues, such as brain therapy, wound healing. Still there is no consistent recommendation on the parameters (dose, light mode, wavelength, irradiance) and protocols (repetition, treatment duration) for its clinical application. Herein, we summarize the current PBM parameters for the treatment of melanoma, and we also discuss the potential photoreceptors and downstream signaling mechanisms in the PBM treatment of melanoma cells. It is hypothesized that PBM may inhibit the melanoma cells by activating mitochondria, OPNs, and other receptors. Regardless of the underlying mechanisms, PBM has been shown to be beneficial in treating melanoma. Through further in-depth studies of the underlying potential mechanisms, it can strengthen the applications of PBM for the therapy of melanoma.

Blue LED causes autophagic cell death in human osteosarcoma by increasing ROS generation and dephosphorylating EGFR

Osteosarcoma (OS) is the most common primary malignant bone tumour in adolescence. Lately, light‐emitting diodes (LED)‐based therapy has emerged as a new promising approach for several diseases. However, it remains unknown in human OS. Here, we found that the blue LED irradiation significantly suppressed the proliferation, migration and invasion of human OS cells, while we observed blue LED irradiation increased ROS production through increased NADPH oxidase enzymes NOX2 and NOX4, as well as decreased Catalase (CAT) expression levels. Furthermore, we revealed blue LED irradiation‐induced autophagy characterized by alterations in autophagy protein markers including Beclin‐1, LC3‐II/LC3‐I and P62. Moreover, we demonstrated an enhanced autophagic flux. The blockage of autophagy displayed a remarkable attenuation of anti‐tumour activities of blue LED irradiation. Next, ROS scavenger N‐acetyl‐L‐cysteine (NAC) and NOX inhibitor diphenyleneiodonium (DPI) blocked suppression of OS cell growth, indicating that ROS accumulation might play an essential role in blue LED‐induced autophagic OS cell death. Additionally, we observed blue LED irradiation decreased EGFR activation (phosphorylation), which in turn led to Beclin‐1 release and subsequent autophagy activation in OS cells. Analysis of EGFR colocalization with Beclin‐1 and EGFR‐immunoprecipitation (IP) assay further revealed the decreased interaction of EGFR and Beclin‐1 upon blue LED irradiation in OS cells. In addition, Beclin‐1 down‐regulation abolished the effects of blue LED irradiation on OS cells. Collectively, we concluded that blue LED irradiation exhibited anti‐tumour effects on OS by triggering ROS and EGFR/Beclin‐1‐mediated autophagy signalling pathway, representing a potential approach for human OS treatment.

Violet-blue light exposure of the skin: is there need for protection?

Advocates of skin protection against blue light express concern about exposure to indoor lighting and electronic screens as well as natural outdoor exposure. However, the nature of adverse effects in skin is unclear and the doses to induce effects are unknown. We aimed to reveal whether there is a scientific basis for promoting skin protection against violet-blue light (400-500 nm, VBL). Based on published literature, we determined the time to reach a threshold dose that induced a biological response in human skin. In the absence of an action spectrum for effects on skin, we used a hand held probe with a defined spectral response and measurements of the unweighted exposure between 400 and 500 nm to estimate the exposure by a selection of artificial light sources and solar light. For comparison, an outdoor threshold erythemally weighted UV dose was set to 1 SED (standard erythema dose). Outdoor, weighted irradiances were obtained using a radiative transfer model. Induction of pigmentation in human skin tissue was the only consistently reported endpoint after VBL exposure of about 65 Jcm^-2. This threshold dose was reached in 0.5 to 20 months of exposure to indoor lighting sources. In comparison, specialised medical sources reached this dose in 0.5 min to 45 h. The time outdoors to reach 1 SED was shorter than the time to reach a VBL threshold dose throughout all seasons. Skin protection against VBL is superfluous for exposures to domestic lighting sources or screens and for solar radiation; however, it may be advantageous for patients suffering from photosensitive diseases or taking photosensitising medication.

Comparative transcriptome analysis of gene expression patterns on B16F10 melanoma cells under Photobiomodulation of different light modes

Cutaneous melanoma is one of the aggressive cancers. Recent studies have shown that Photobiomodulation (PBM) can inhibit the proliferation of melanoma cells. However, it is not clear that the effect of PBM light mode on the inhibition of melanoma cells. Herein, we investigated the difference of influence between continuous wave (CW) and Pulse PBM on B16F10 melanoma cells. Our results suggested that Pulse mode had a more significant inhibition on the viability of B16F10 melanoma cells than CW mode under the PBM light parameter of wavelength, dose, and average irradiance at 457 nm, 1.14 J/cm2, and 0.19 mW/cm2. Besides, we revealed the differentially expressed genes of B16F10 melanoma cells under the various treatments of PBM light mode (not PBM treatment, CW mode, and Pulse mode) by RNA sequencing. Together, our data suggested that Pulse-PBM can improve the effect of PBM on cells significantly and there may be different molecular mechanisms between Pulse and CW mode including anti-proliferative and cell necrosis. The study shed new light on investigating the molecular mechanisms of various PBM light modes on B16F10 melanoma cells.

Light-emitting diode irradiation induces AKT/mTOR-mediated apoptosis in human pancreatic cancer cells and xenograft mouse model

The beneficial effects of light-emitting diode (LED) irradiation have been reported in various pathologies, including cancer. However, its effect in pancreatic cancer cells remains unclear. Herein, we demonstrated that blue LED of 460 nm regulated pancreatic cancer cell proliferation and apoptosis by suppressing the expression of apoptosis-related factors, such as mutant p53 and B-cell lymphoma 2 (Bcl-2), and decreasing the expression of RAC-β serine/threonine kinase 2 (AKT2), the phosphorylation of protein kinase B (AKT), and mammalian target of rapamycin (mTOR). Blue LED irradiation also increased the levels of cleaved poly-(ADP-ribose) polymerase (PARP) and caspase-3 in pancreatic cancer cells, while it suppressed AKT2 expression and inhibited tumor growth in xenograft tumor tissues. In conclusion, blue LED irradiation suppressed pancreatic cancer cell and tumor growth by regulating AKT/mTOR signaling. Our findings indicated that blue LEDs could be used as a nonpharmacological treatment for pancreatic cancer.

Reduced graphene oxide, but not carbon nanotubes, slows murine melanoma after thermal ablation using LED light in B16F10 lineage cells

Photodynamic therapy is a minimally invasive health technology used to treat cancer and other non-malignant diseases, as well as inactivation of viruses, bacteria and fungi. In this work, we sought to combine the phototherapy technique using low intensity LED (660 nm) to induce ablation in melanoma tumor in mice treated with nanoparticles. In vitro and in vivo studies were conducted, and our results demonstrated that multi-walled carbon nanotubes (MWCNTs) do not destroy tumor cells in vivo, but stimulate the inflammatory process and angiogenesis. Reduced graphene oxide (rGO), has been shown to play a protective role associated with the LED ablation, inducing necrosis, stimulation of immune response by lymphoproliferation, and decreased tumor mass in vivo. We consider that LED alone can be very effective in controlling the growth of melanoma tumors and its association with rGO is potentiated.

Conditioned media from blue light-emitting diode-exposed fibroblasts have an anti-inflammatory effect in vitro

We have previously reported the protective effects of blue light-emitting diode (BLED)-stimulated cell metabolites on cell injury. To further examine the effect of conditioned media (CM) derived from BLED (5 J/cm²)-exposed human normal fibroblasts (CMBL5) for clinical application, we have used the choline chloride and phenol red-free media and then concentrated CMBL5 using a centrifugal filter unit. The collected CMBL5-lower part (CMBL5-LO) has evaluated the inflammatory protein expression profile in LPS-stimulated RAW264.7 cells. Comprehensive metabolomic profiling of CMBL5-LO was carried out using hybrid tandem mass spectrometry. Treatment with CMBL5-LO showed the cytoprotective effect on apoptotic cell death, but rather increased apoptotic cells after treatment with CMBL5-upper part (CMBL5-UP). In addition, CMBL5-LO inhibited several chemo-attractants, including interleukin (IL)-6, macrophage inflammatory protein (MIP)-2, chemokine (C-C motif) ligand 5 (CCL5), granulocyte colony-stimulating factor (GCSF), and monocyte chemoattractant protein-1 (MCP-1) expression. Pro-inflammatory nitric oxide was decreased after CMBL5-LO treatment, but not by CMBL5-UP treatment. Interestingly, treatment with CMBL5-LO stimulated expression of heme oxygenase-1, indicating its anti-inflammatory property. Most endoplasmic reticulum (ER) stress proteins except for transcription factor C/EBP homologous protein (CHOP) were highly expressed after irradiation with BLED in cells. Further studies are needed to examine the precise mechanism by CMBL5-LO in cells.

The strong inhibitory effect of combining anti-cancer drugs AT406 and rocaglamide with blue LED irradiation on colorectal cancer cells

There is still no satisfying method to treat colorectal cancer (CRC) currently. Inspired by cocktail therapy, the combination of 465 nm blue LED irradiation and two multi-target anticancer agents AT406 and Rocaglamide has been investigated as an innovative way to treat colorectal cancer cells in vitro. It showed a strong inhibitory effect on colorectal cancer cells, and its side effects on human normal cells are negligible. When applied to HCT116 cells, it can achieve an apoptotic rate up to 95%. It is also seen to significantly inhibit proliferation of HT29 cells. Furthermore, little to no cell inhibition or damage of normal MRC-5 cells were seen after treatment. The combination of blue LED irradiation and two anti-cancer drugs causes apoptosis of colorectal cancer cells by activating the apoptotic pathway, inhibiting autophagy and proliferation pathways as well as the production of reactive oxygen species (ROS).

RNA-Seq analysis revealed the molecular mechanisms of photobiomodulation effect on human fibroblasts

BACKGROUND

The photobiomodulation (PBM) effect has been applied to various clinical therapy for a long time. However, the mechanism related to the PBM effect in terms of wavelengths has been lack of in-depth study, except that ultraviolet radiation has attracted much attention due to its strong cell-killing effect.

PURPOSE

To clarify the principle behind PBM and the main mechanism of improvement.

METHODS

To carry on this study, we created light equipment using three LED chips, which emit 390 nm ultraviolet radiation, 415 nm blue light and 660 nm red light, respectively. We choose human fibroblasts (HF) to be irradiated by three different wavelengths for PBM test. In this study, we used cell counting kit (CCK-8) test to show the cell proliferation roughly and reported on a systematic RNA sequencing (RNA-seq) analysis at transcriptional expression levels from HF, which accepted PBM of different wavelengths of light.

RESULTS

We found that 415 nm blue light inhibited cell proliferation and 660 nm red light stimulated cell proliferation while 390 nm ultraviolet radiation has little influence on cell proliferation. Furthermore, RNA-seq results showed that CSF1R, PPP3CC, ITGAL, ITGAM, IL2RB, and several other differentially expressed genes (DEGs) are involved in the cell proliferation. Relative DEGs values for matrix metalloproteinases (MMPs) gene family have shown a great difference in blue and red light radiation especially on MMP25, MMP9, MMP21, and MMP13.

CONCLUSION

Taken together, the results provide a valuable resource to describe the variation of HFs under PBM of different light at gene level.

Quantitative Phase Dynamics of Cancer Cell Populations Affected by Blue Light

Increased exposition to blue light may induce many changes in cell behavior and significantly affect the critical characteristics of cells. Here we show that multimodal holographic microscopy (MHM) within advanced image analysis is capable of correctly distinguishing between changes in cell motility, cell dry mass, cell density, and cell death induced by blue light. We focused on the effect of blue light with a wavelength of 485 nm on morphological and dynamical parameters of four cell lines, malignant PC-3, A2780, G361 cell lines, and the benign PNT1A cell line. We used MHM with blue light doses 24 mJ/cm2, 208 mJ/cm2 and two kinds of expositions (500 and 1000 ms) to acquire real-time quantitative phase information about cellular parameters. It has been shown that specific doses of the blue light significantly influence cell motility, cell dry mass and cell density. These changes were often specific for the malignant status of tested cells. Blue light dose 208 mJ/cm2 × 1000 ms affected malignant cell motility but did not change the motility of benign cell line PNT1A. This light dose also significantly decreased proliferation activity in all tested cell lines but was not so deleterious for benign cell line PNT1A as for malignant cells. Light dose 208 mJ/cm2 × 1000 ms oppositely affected cell mass in A2780 and PC-3 cells and induced different types of cell death in A2780 and G361 cell lines. Cells obtained the least damage on lower doses of light with shorter time of exposition.

Phototherapy alters the oncogenic metabolic activity of breast cancer cells

BACKGROUND

Metabolic reprogramming in cancer cells is a strategy to attain a high proliferation rate, invasion, and metastasis. In this study, the effects of phototherapy at different wavelengths were investigated on the metabolic activity of breast cancer cells.

METHODS

The states of the MCF7 cells proliferation and viability were measured by the MTT assay. Glucose consumption and the lactate formation in the LED-irradiated cells culture were analyzed by biochemical assay kits. The Amino acid concentration in the culture media of the MCF7 cells was analyzed using HPLC. Moreover, the gene expression of some glycolytic, TCA cycle and pentose phosphate cycleenzymes were assessed by real time PCR.

RESULTS

Phototherapy at wavelength of 435 nm decreased the cell viability by 23 % when the energy dose was 17.5 J/cm² compared to the control group. The expression of the LDHA and GLS was up-regulated in 629 nm-treated cells while the expression of these genes was down-regulated in the MCF7 cells irradiated at 435 nm in comparison with the control group. Consequently, the glucose consumption and the lactate formation were diminished respectively by 22 % and 15 % in the 435 nm-irradiated cells while the glucose consumption and the lactate formation were increased in the 629 nm-irradiated cells by 112 % and 107 % in comparison with the control group. In addition, the analysis of the glutamine concentration by the HPLC indicated that the blue light irradiation decreased the glutamine consumption while the red light increased it in comparison with the control group.

Curcuminoids encapsulated liposome nanoparticles as a blue light emitting diode induced photodynamic therapeutic system for cancer treatment

Unlike normal cells, cancer cells mutate to thrive in exaggerated levels of reactive oxygen species (ROS). This potentially makes them more susceptible to small molecule-induced oxidative stress. The intracellular ROS increase in cancer cells is a potential area under investigation for the development of cancer therapeutics targeting cancer cells. Visible photons of 430-490 nm wavelengths from a blue-light emitting diode (BLED) encompass the visible region of the spectrum known to induce ROS in cancer cells. Curcuminoids (CUR) naturally occurring photosensitizers sensitized by the blue wavelength of the visible light, well known for its potent anti-inflammatory and anticancer activity. Poor solubility and bioavailability, of the compound of the small molecule CUR restrict the therapeutic potential and limits CUR to be used as a photosensitizer. Here, our research group reports the use of small molecules CUR, encapsulated in liposome nanocarriers (LIP-CUR) coupled with blue light-emitting diode (BLED) induced photodynamic therapy (BLED-PDT). In A549 cancer cells in vitro, LIP-CUR coupled with BLED initiated BLED-PDT and triggered ¹O₂, ultimately resulting in caspase-3 activated apoptotic cell death. The combination of a non-cytotoxic dose of small molecule CUR co-treated with BLED to trigger BLED-PDT could be translated and be developed as a novel strategy for the treatment of cancer.

Irradiance plays a significant role in photobiomodulation of B16F10 melanoma cells by increasing reactive oxygen species and inhibiting mitochondrial function

Melanoma is a type of aggressive cancer. Recent studies have indicated that blue light has an inhibition effect on melanoma cells, but the effect of photobiomodulation (PBM) parameters on the treatment of melanoma remains unknown. Thus, this study was aimed to investigate B16F10 melanoma cells responses to PBM with varying irradiance and doses, and further explored the molecular mechanism of PBM. Our results suggested that the responses of B16F10 melanoma cells to PBM with varying irradiance and dose were different and the inhibition of blue light on cells under high irradiance was better than low irradiance at a constant total dose (0.04, 0.07, 0.15, 0.22, 0.30, 0.37, 0.45, 0.56 or 1.12 J/cm²), presumably due to that high irradiance can produce more ROS, thus disrupting mitochondrial function.

A Macro Lens-Based Optical System Design for Phototherapeutic Instrumentation

Light emitting diode (LED) and ultrasound have been powerful treatment stimuli for tumor cell growth due to non-radiation effects. This research is the first preliminary study of tumor cell suppression using a macro-lens-supported 460-nm LED combined with high-frequency ultrasound. The cell density, when exposed to the LED combined with ultrasound, was gradually reduced after 30 min of induction for up to three consecutive days when 48-W DC, 20-cycle, and 50 V_p-p sinusoidal pulses were applied to the LEDs through a designed macro lens and to the ultrasound transducer, respectively. Using a developed macro lens, the non-directional light beam emitted from the LED could be localized to a certain spot, likewise with ultrasound, to avoid additional undesirable thermal effects on the small sized tumor cells. In the experimental results, compared to LED-only induction (14.49 ± 2.73%) and ultrasound-only induction (13.27 ± 2.33%), LED combined with ultrasound induction exhibited the lowest cell density (6.25 ± 1.25%). Therefore, our measurement data demonstrated that a macro-lens-supported 460-nm LED combined with an ultrasound transducer could possibly suppress early stage tumor cells effectively.

Visible Blue Light Therapy: Molecular Mechanisms and Therapeutic Opportunities

BACKGROUND

Visible light is absorbed by photoacceptors in pigmented and non-pigmented mammalian cells, activating signaling cascades and downstream mechanisms that lead to the modulation of cellular processes. Most studies have investigated the molecular mechanisms and therapeutic applications of UV and the red to near infrared regions of the visible spectrum. Considerably less effort has been dedicated to the blue, UV-free part of the spectrum.

OBJECTIVE

In this review, we discuss the current advances in the understanding of the molecular photoacceptors, signaling mechanisms, and corresponding therapeutic opportunities of blue light photoreception in non-visual mammalian cells in the context of inflammatory skin conditions.

METHODS

The literature was scanned for peer-reviewed articles focusing on the molecular mechanisms, cellular effects, and therapeutic applications of blue light.

RESULTS

At a molecular level, blue light is absorbed by flavins, porphyrins, nitrosated proteins, and opsins; inducing the generation of ROS, nitric oxide release, and the activation of G protein coupled signaling. Limited and contrasting results have been reported on the cellular effects of blue light induced signaling. Some investigations describe a regulation of proliferation and differentiation or a modulation of inflammatory parameters; others show growth inhibition and apoptosis. Regardless of the elusive underlying mechanism, clinical studies show that blue light is beneficial in the treatment of inflammatory skin conditions.

CONCLUSION

To strengthen the use of blue light for therapeutic purposes, further in depth studies are clearly needed with regard to its underlying molecular and cellular mechanisms, and their translation into clinical applications.

Synergistic effect of phototherapy and chemotherapy on bladder cancer cells

Drug resistance as an important barrier to cancer treatment, has a close relation with alteration of cancer metabolism. Therefore, in this study the synergistic effect of phototherapy and chemotherapy were investigated on the bladder cancer cells viability. The cytotoxicity effect of blue light irradiation was measured by the MTT assay. Glucose consumption, lactate and ammonium formation were analyzed in the blue LED-irradiated cancer cells culture. Also, the expression of some genes involved in apoptosis and epithelial-mesenchymal transition was assessed using real-time PCR in comparison with the control group. The analysis of the results indicated that blue light irradiation inhibited the cell viability in a dose-dependent manner. Blue light irradiation decreased the cell viability by 7% and 19% (p < .05) in 5637 cells at doses of 8.7 J/cm² and 17.5 J/cm² in comparison with the control group respectively. Glucose consumption, lactate and ammonium formation diminished in the blue LED-irradiated 5637 cells in both doses. The real time PCR results indicated that the expression of Bax increased in blue light-irradiated cells. In addition, the cell cycle analysis showed that blue light irradiation arrested the bladder cancer in the G1 phase. Also, the effect of combination therapy on cancer cells was investigated in presence of blue light irradiation and cisplatin. The obtained results of the MTT assay indicated that blue light irradiation enhance the cytotoxicity effect of cisplatin on bladder cancer cells.

Synergistic anti-tumor effects of arsenic trioxide and blue LED irradiation on human osteosarcoma

Arsenic trioxide (ATO) has been well recognized as an anti-tumor agent for various human cancers. Recently, the blue light emitting diodes (LEDs)-based therapy has also been demonstrated to be potential therapeutic strategies for several cancers. However, the combination effects of ATO and blue LED on tumor suppression are still unclear. In this study, we determined whether combination of ATO and blue LED irradiation at 470 nm in wavelength exhibited superior anti-tumor activity in human osteosarcoma (OS). We observed that combination treatments of ATO and blue LED much more significantly decreased the percentages of proliferative cells, and increased apoptotic rate compared with any single treatments in U-2 OS cells. Furthermore, we found suppression of cell migration and invasion were much more pronounced in ATO plus blue LED treated group than single treated groups. Moreover, reactive oxygen species (ROS) assay and immunostaining of γ-H2A.X and p53 indicated that the combined treatments resulted in further markedly increases in ROS accumulation, DNA damage and p53 activity. Taken together, our study demonstrated synergistical anti-tumor effects of combined treatments of ATO and blue LED on human OS cells, which were associated with an increased ROS accumulation, DNA damaged mediated p53 activation.

Protective Effect of BLED-exposed Conditioned Media on Cell Injury

Previous studies have reported that 450 nm blue light emitting diode (BLED) induces apoptosis through a mitochondria-mediated pathway in cancer cells and reduces the early stage tumor growth. This study was performed to determine the effects of BLED-irradiated cell metabolites on cell injury. Our results showed that conditioned medium (CM) from cells irradiated with low-dose BLED (LCM) inhibited apoptosis and increased cell survival. Cell protection-related proteins were identified in cell metabolites of CM and LCM using 2-DE and MALDI-TOF analysis. Treatment with LCM inhibited apoptotic cell death and increased the live cell population. The cellular protective effect of LCM was associated with keratin and collagen type VI secretion from cells after low dose of BLED irradiation. Interestingly, expression of endoplasmic reticulum stress proteins was dose dependently increased after 4 h BLED irradiation. Only levels of BiP, CHOP and ERO1-Lα were decreased significantly after 24 h incubation, indicating their anti-apoptotic property in these cells. These results indicated that cell metabolites stimulated by low-dose BLED irradiation have a cytoprotective effect on cell injury via increasing transient intracellular ER stress. Further studies remain to provide the molecular mechanisms of LCM for cytoprotective activity.

Blue light-emitting diodes induce autophagy in colon cancer cells by Opsin 3

Background

Light emitting-diodes (LED) have various effects on living organisms and recent studies have shown the efficacy of visible light irradiation from LED for anticancer therapies. However, the mechanism of LED's effects on cancer cells remains unclear. The aim of the present study was to investigate the effects of LED on colon cancer cell lines and the role of photoreceptor Opsin 3 (Opn3) on LED irradiation in vitro.

Methods

Human colon cancer cells (HT-29 or HCT-116) were seeded onto laboratory dishes and irradiated with 465-nm LED at 30 mW/cm² for 30 minutes. Cell Counting Kit-8 was used to measure cell viability, and apoptosis and caspase 3/8 expression were evaluated by AnnexinV/PI and reverse transcription-polymerase chain reaction (RT-PCR), respectively. Autophagy and expression of LC-3 and beclin-1 were also evaluated by autophagy assays, RT-PCR and Western blotting. We further tested Opn3 knockdown by Opn3 siRNA and the G_i/o G-protein inhibitor NF023 in these assays.

Results

Viability of HT-29 and HCT-116 cells was lower in 465-nm LED-irradiated cultures than in control cultures. LC-3 and beclin-1 expressions were significantly higher in LED-irradiated cultures, and autophagosomes were detected in irradiated cells. The reductive effect of cancer cell viability following blue LED irradiation was reversed by Opn3 knockdown or NF023 treatment. Furthermore, increased LC-3 and beclin-1 expression that resulted from blue LED irradiation was suppressed by Opn3 knockdown or NF023 treatment.

Conclusion

Blue LED irradiation suppressed the growth of colon cancer cells and Opn3 may play an important role as a photoreceptor.

White light emitting diode suppresses proliferation and induces apoptosis in hippocampal neuron cells through mitochondrial cytochrome c oxydase-mediated IGF-1 and TNF-α pathways

Light emitting diode (LED) light has been tested to treat traumatic brain injury, neural degenerative diseases and psychiatric disorders. Previous studies indicate that blue LED light affects cell proliferation and apoptosis in photosensitive cells and cancer cells. In this study, we demonstrate that white LED light exposure impaired proliferation and induced apoptosis in HeLa and HT-22 hippocampal neural cells, but not C2C12 cells. Furthermore, the mechanisms underlying the effect of white LED light exposure on HT-22 cells were elucidated. In HeLa and HT-22 cells, white LED light activated mitochondrial cytochrome c oxidase (Cco), in association with enhanced ATP synthase activity and elevated intracellular ATP concentration. Also, reactive oxygen species (ROS) and nitric oxide (NO) production were increased, accompanied by higher calcium concentration and lower mitochondrial membrane potential. HT-22 cells exposed to white LED light for 24h showed reduced viability, with higher apoptotic rate and a cell cycle arrest at G0/G1 phase. Concurrently, the mRNA expression and the concentration of IGF-1 were decreased, while that of TNF-α were increased, in light-exposed cells, which was supported by the luciferase activity of both gene promoters. The down-stream mitogen-activated protein kinase (MAPK), AKT/mTOR pathways were inhibited, in association with an activation of apoptotic caspase 3. N-Acetylcysteine, a ROS scavenger, protected the cells from LED light-induced cellular damage, with rescued cell viability and restored mRNA expression of IGF-1 and TNF-α. Our data demonstrate that white LED light suppresses proliferation and induces apoptosis in hippocampal neuron cells through mitochondrial Cco/ROS-mediated IGF-1 and TNF-α pathways.

Combinational light emitting diode-high frequency focused ultrasound treatment for HeLa cell

PURPOSE

Light sources such as laser and light emitting diode or ultrasound devices have been widely used for cancer therapy and regenerative medicines, since they are more cost-effective and less harmful than radiation therapy, chemotherapy or magnetic treatment. Compared to laser and low intensity ultrasound techniques, light emitting diode and high frequency focused ultrasound shows enhanced therapeutic effects, especially for small tumors.

MATERIALS AND METHODS

We propose combinational light emitting diode-high frequency focused ultrasound treatment for human cervical cancer HeLa cells. Individual red, green, and blue light emitting diode light only, high frequency focused ultrasound only, or light emitting diode light combined with high frequency focused ultrasound treatments were applied in order to characterize the responses of HeLa cells.

RESULTS

Cell density exposed by blue light emitting diode light combined with high frequency focused ultrasound (2.19 ± 0.58%) was much lower than that of cells exposed by red and green light emitting diode lights (81.71 ± 9.92% and 61.81 ± 4.09%), blue light emitting diode light (11.19 ± 2.51%) or high frequency focused ultrasound only (9.72 ± 1.04%).

CONCLUSIONS

We believe that the proposed combinational blue light emitting diode-high frequency focused ultrasound treatment could have therapeutic benefits to alleviate cancer cell proliferation.

Inhibitory effect of blue light emitting diode on migration and invasion of cancer cells

The aim of this study was to determine the effects and molecular mechanism of blue light emitting diode (LED) in tumor cells. A migration and invasion assay for the metastatic behavior of mouse colon cancer CT-26 and human fibrosarcoma HT-1080 cells was performed. Cancer cell migration-related proteins were identified by obtaining a 2-dimensional gel electrophoresis (2-DE) in total cellular protein profile of blue LED-irradiated cancer cells, followed by matrix-assisted laser desorption/ionization-time of flight (MALDI-TOF) analysis of proteins. Protein levels were examined by immunoblotting. Irradiation with blue LED inhibited CT-26 and HT-1080 cell migration and invasion. The anti-metastatic effects of blue LED irradiation were associated with inhibition of matrix metalloproteinase (MMP)-2 and MMP-9 expression. P38 MAPK phosphorylation was increased in blue LED-irradiated CT-26 and HT-1080 cells, but was inhibited after pretreatment with SB203580, a specific inhibitor of p38 MAPK. Inhibition of p38 MAPK phosphorylation by SB203580 treatment increased number of migratory cancer cells in CT-26 and HT-1080 cells, indicating that blue LED irradiation inhibited cancer cell migration via phosphorylation of p38 MAPK. Additionally blue LED irradiation of mice injected with CT-26 cells expressing luciferase decreased early stage lung metastasis compared to untreated control mice. These results indicate that blue LED irradiation inhibits cancer cell migration and invasion in vitro and in vivo.

An in vitro cell irradiation protocol for testing photopharmaceuticals and the effect of blue, green, and red light on human cancer cell lines

Traditionally, ultraviolet light (100-400 nm) is considered an exogenous carcinogen while visible light (400-780 nm) is deemed harmless. In this work, a LED irradiation system for in vitro photocytotoxicity testing is described. The LED irradiation system was developed for testing photopharmaceutical drugs, but was used here to determine the basal level response of human cancer cell lines to visible light of different wavelengths, without any photo(chemo)therapeutic. The effects of blue (455 nm, 10.5 mW cm(-2)), green (520 nm, 20.9 mW cm(-2)), and red light (630 nm, 34.4 mW cm(-2)) irradiation was measured for A375 (human malignant melanoma), A431 (human epidermoid carcinoma), A549 (human lung carcinoma), MCF7 (human mammary gland adenocarcinoma), MDA-MB-231 (human mammary gland adenocarcinoma), and U-87 MG (human glioblastoma-grade IV) cell lines. In response to a blue light dose of 19 J cm(-2), three cell lines exhibited a minimal (20%, MDA-MB-231) to moderate (30%, A549 and 60%, A375) reduction in cell viability, compared to dark controls. The other cell lines were not affected. Effective blue light doses that produce a therapeutic response in 50% of the cell population (ED50) compared to dark conditions were found to be 10.9 and 30.5 J cm(-2) for A375 and A549 cells, respectively. No adverse effects were observed in any of the six cell lines irradiated with a 19 J cm(-2) dose of 520 nm (green) or 630 nm (red) light. The results demonstrate that blue light irradiation can have an effect on the viability of certain human cancer cell types and controls should be used in photopharmaceutical testing, which uses high-energy (blue or violet) visible light activation.

Data in support of effect of blue LED irradiation in human lymphoma cells

As a new and preferred light source for phototherapy, blue light emitting diodes (LEDs) with wavelengths of 400-500 nm have been used to treat hyperbilirubinaemia in infantile jaundice [1]. Recent studies report that blue LED irradiation induces apoptosis by stimulating a mitochondrial pathway and reduces the early growth rate of melanoma cells in mice [2]. Here, we detected the induction of apoptotic cell death and formation of autophagosome in human B lymphoma cells after irradiation with blue LED. This paper provides data in support of the research article entitled "Blue light emitting diode induces apoptosis in lymphoid cells by stimulating autophagy" [3].