Ergonomic artificial lighting: study of the chronobiological effects of light radiations on human health

La radiazione visibile ha effetti sul ciclo circadiano degli organismi viventi. Questa tesi ha studiato gli effetti cronobiologici della radiazione luminosa in vitro su cheratinociti e in vivo su Drosophila melanogaster. Sono stati studiati gli effetti di una esposizione di tre giorni a radiazione luminosa blu e rossa emessa da LED rispetto ad un gruppo di controllo tenuto al buio. Su cellule di cheratinociti (HaCaT) sono stati studiati: la vitalità cellulare, l'apoptosi, il ciclo cellulare, l'espressione dei geni circadiani e la proteomica. Su Drosophila melanogaster sono state studiate: la risposta a stress termici e al paraquat, la motilità e l'espressione di alcuni geni clock. La radiazione luminosa ha diversi effetti biologici sui cheratinociti, in relazione alla lunghezza d'onda, al tempo di esposizione e all'intensità. Un’esposizione di 12h di luce blu ad alta intensità per tre giorni ha ridotto la proliferazione cellulare, aumentato l'apoptosi, modificato il ciclo cellulare, sincronizzato gli orologi circadiani, alterato i livelli proteici della classe ossidoreduttasi, aumentato la concentrazione di ROS intracellulari. Nei moscerini esposti per tre giorni a luce blu, sono stati osservati una diminuzione del tempo di recupero dal coma indotto dal freddo, una diminuzione della sopravvivenza se sottoposti a trattamento con alta temperatura, un aumento della tossicità al paraquat, un’aumento della motilità e una sovraespressione dei geni clock. Nei nostri modelli la luce blu ha effetti cronobiologici. La luce blu diminuisce la vitalità dei cheratinociti e l’effetto dipende del tempo di esposizione e dall’intensità. I cheratinociti possiedono una regolazione autonoma del ciclo circadiano probabilmente per far fronte a insulti tossici (luce blu) dall'ambiente esterno. Negli insetti è stato possibile osservare una risposta dopo l’esposizione a luce blu; i geni clock risultano overespressi e alcune funzioni ritmiche circadiane sono modificate.Visible radiation affects the circadian cycle of living organisms. This thesis studied the chronobiological effects of light radiation in vitro on keratinocytes and in vivo on Drosophila melanogaster. The effects of a three-day exposure to blue and red light radiation emitted by LEDs on these two models were compared with a control group kept in the dark. On keratinocytes (HaCaT) cell viability, apoptosis, cell cycle, circadian gene expression and proteomics were analysed. On Drosophila melanogaster the response to thermal stress and paraquat, motility and expression of some clock genes were studied. Light radiation has different biological effects on keratinocytes, due to wavelength, exposure time and intensity. Exposure to 12-hour high-intensity blue light for three days reduced cell proliferation, increased apoptosis, modified the cell cycle, synchronized circadian clocks, altered oxidoreductase class protein levels, and increased intracellular ROS concentration. The same exposure in Drosophila melanogaster decreased recovery time from cold-induced coma, decreased survival to high temperature treatment, increased toxicity to paraquat, increased motility, and induced overexpression of clock genes. In our models, blue light has chronobiological effects. Blue light decreases keratinocyte viability in a time- and intensity-dependent manner. Keratinocytes have autonomous regulation of the circadian cycle probably to address toxic insults (blue light) from the external environment. In insects, a response could be observed after exposure to blue light; clock genes are over-expressed and some circadian rhythmic functions are modified

Exosomal miR-92a Concentration in the Serum of Shift Workers

Shift work is associated with alterations in the human biological clock and metabolism. Serum exosomal miR-92a concentration was inversely correlated with brown adipose tissue activity playing a pivotal role in energy balance. In this study, miR-92a was measured in serum exosomes of 30 workers engaged in shift and daytime work. No significant metabolic alterations were shown between daytime and shift workers while a difference in serum exosomal miR-92a levels was found between the two groups. The lower levels of miR-92a in shift workers were suggestive of a higher brown adipose tissue activity compared with daytime workers. However, the possibility that other physiological and pathological processes may influence miR-92a cannot be ruled out. Our results suggest further investigations on brown adipose tissue activity and on miR-92a regulatory mechanisms, such as those related to the estrogen pathway, in shift workers

Apoptotic mechanism activated by blue light and cisplatinum in cutaneous squamous cell carcinoma cells

New approaches are being studied for the treatment of skin cancer. It has been reported that light combined with cisplatinum may be effective against skin cancer. In the present study, the effects of specific light radiations and cisplatinum on A431 cutaneous squamous cell carcinoma (cSCC) and HaCaT non‑tumorigenic cell lines were investigated. Both cell lines were exposed to blue and red light sources for 3days prior to cisplatinum treatment. Viability, apoptosis, cell cycle progression and apoptotic‑related protein expression levels were investigated. The present results highlighted that combined treatment with blue light and cisplatinum was more effective in reducing cell viability compared with single treatments. Specifically, an increase in the apoptotic rate was observed when the cells were treated with blue light and cisplatinum, as compared to treatment with blue light or cisplatinum alone. Combined treatment with blue light and cisplatinum also caused cell cycle arrest at the S phase. Treatment with cisplatinum following light exposure induced the expression of apoptotic proteins in the A431 and HaCaT cell lines, which tended to follow different apoptotic mechanisms. On the whole, these data indicate that blue light combined with cisplatinum may be a promising treatment for cSCC

Effects of extremely low-frequency magnetic fields on human MDA-MB-231 breast cancer cells: proteomic characterization

: Extremely low-frequency electromagnetic fields (ELF-MF) can modify the cell viability and regulatory processes of some cell types, including breast cancer cells. Breast cancer is a multifactorial disease where a role for ELF-MF cannot be excluded. ELF-MF may influence the biological properties of breast cells through molecular mechanisms and signaling pathways that are still unclear. This study analyzed the changes in the cell viability, cellular morphology, oxidative stress response and alteration of proteomic profile in breast cancer cells (MDA-MB-231) exposed to ELF-MF (50 Hz, 1 mT for 4 h). Non-tumorigenic human breast cells (MCF-10A) were used as control cells. Exposed MDA-MB-231 breast cancer cells increased their viability and live cell number and showed a higher density and length of filopodia compared with the unexposed cells. In addition, ELF-MF induced an increase of the mitochondrial ROS levels and an alteration of mitochondrial morphology. Proteomic data analysis showed that ELF-MF altered the expression of 328 proteins in MDA-MB-231 cells and of 242 proteins in MCF-10A cells. Gene Ontology term enrichment analysis demonstrated that in both cell lines ELF-MF exposure up-regulated the genes enriched in "focal adhesion" and "mitochondrion". The ELF-MF exposure decreased the adhesive properties of MDA-MB-231 cells and increased the migration and invasion cell abilities. At the same time, proteomic analysis, confirmed by Real Time PCR, revealed that transcription factors associated with cellular reprogramming were upregulated in MDA-MB-231 cells and downregulated in MCF-10A cells after ELF-MF exposure. MDA-MB-231 breast cancer cells exposed to 1 mT 50 Hz ELF-MF showed modifications in proteomic profile together with changes in cell viability, cellular morphology, oxidative stress response, adhesion, migration and invasion cell abilities. The main signaling pathways involved were relative to focal adhesion, mitochondrion and cellular reprogramming

BRCA1 and BRCA2 Gene Expression: Diurnal Variability and Influence of Shift Work

BRCA1 and BRCA2 genes are involved in DNA double-strand break repair and related to breast cancer. Shift work is associated with biological clock alterations and with a higher risk of breast cancer. The aim of this study was to investigate the variability of expression of BRCA genes through the day in healthy subjects and to measure BRCA expression levels in shift workers. The study was approached in two ways. First, we examined diurnal variation of BRCA1 and BRCA2 genes in lymphocytes of 15 volunteers over a 24-hour period. Second, we measured the expression of these genes in lymphocytes from a group of shift and daytime workers. The change in 24-hour expression levels of BRCA1 and BRCA2 genes was statistically significant, decreasing from the peak at midday to the lowest level at midnight. Lower levels for both genes were found in shift workers compared to daytime workers. Diurnal variability of BRCA1 and BRCA2 expression suggests a relation of DNA double-strand break repair system with biological clock. Lower levels of BRCA1 and BRCA2 found in shift workers may be one of the potential factors related to the higher risk of breast cancer