Effects of wood dust:Inflammation, Genotoxicity and Cancer.

Jette Bornholdt Lange

Effects of wood dust:Inflammation, Genotoxicity and Cancer.

Jette Bornholdt Lange

Abstract

Denne ph.d. afhandling omhandler inflammatoriske, genotoksiske og karcinogene effekter efter eksponering for træstøv fra forskellige træsorter. Eksperimenterne udført i forbindelse med dette projekt, var delt i to. Den første del omhandlede en in vitro model, hvor den humane lunge epitel celle linje A549 blev brugt, til at bestemme inflammatoriske og DNA skadende effekter. Den anden del bestod i en molekylær analyse af humane sinonasale tumourer for mutationer i det kræft relaterede gen K-ras. Mutationer i kodon 12, 13, og 61, såkaldte 'hotspot' kodons blev bestemt. I forbindelse med disse forsøg blev kalibrering og validering af alle de brugt metoder udført.

Kræft i næse og bihuler er sjældent. I Europa er forekomsten af nydiagnosticerede tilfælde på mellem 0,3 til 1,4 per 100 000 indbyggere for mænd og mellem 0,1 og 0,8 per 100 000 for kvinder, afhængigt af hvilket land man ser på. Til trods for den lave hyppighed ses en stærk sammenhæng mellem kræft i næse og bihuler og erhvervsmæssig udsættelser for især træstøv. Professionel udsættelse for træstøv, især fra hårde træsorter, er blevet stærkt associeret med histologi typen adenokarcinom. Ikke maligne symptomer så som allergi, astma, rhinitis og kronisk bronkitis kan ligeledes i epidemiologiske undersøgelser relateres til en professionel udsættelse for træstøv. I de fleste studier er træstøv fra hårde træsorter (f.eks. eg og bøg) mere karcinogene og har en stærkere association til de ikke maligne symptomer sammenlignet med støv fra bløde træsorter (f.eks. fyr og gran). Da standardiserede og kontrollerede forsøg med hensyn til eksponering er svært at udføre på mennesker, er de underliggende mekanismer bag træstøvs effekter mangelfuldt kortlagt. Det er blevet foreslået at partikel induceret inflammation, så vel som de indholdsstoffer der er i selve træet kan virke karcinogene.I dette projekt eksponerede jeg den humane lunge epitel celle linje A549 for træstøv fra forskellige træsorter og målte markører for inflammation og genotoksicitet. Resultaterne viste, at de forskellige træsorter varierer i deres potentiale til at give DNA streng brud og til at kunne inducere en inflammations proces. Der var umiddelbart ingen sammenhæng mellem en træsorts evne til at forårsage inflammation og dets genotoksiske potentiale. I modsætning til vores hypotese, var inflammation ikke den direkte årsag til DNA streng brudene, ligesom træstøv fra hårdt træ ikke var mere inflammatoriske eller genotoksiske i forholdt til støv fra blødt træ.

Originalsprog	Engelsk

Forlag	Museum Tusculanum
Status	Udgivet - 2008

FN’s Verdensmål

Dette resultat bidrager til følgende verdensmål

Citationsformater

@phdthesis{0a6f08a0ed4811ddbf70000ea68e967b,

title = "Effects of wood dust:Inflammation, Genotoxicity and Cancer.",

abstract = "The present thesis focuses on the inflammatory, genotoxic and carcinogenic effects of exposure to different species of wood dust. The experimental work performed in this thesis consists of two parts. The first part of the study was carried out in an in vitro model with the human lung epithelial cell line A549 measuring inflammatory and DNA damaging effects. The second part consists of a molecular analysis of the K-ras gene for mutations in the hotspots codons in human sinonasal cancers. Design, calibration and validation of the assays were performed.Cancer at the sinonasal cavities is rare with incidence rates between of 0.3 to 1.4 per 100,000 for men and 0.1 to 0.8 per 100,000 for women in Europe, depending on country. However, cancer at this site is associated with occupational exposures including wood dust. Especially the adenocarcinoma subtype is strongly associated with exposure to wood dust primarily from hard woods. Non-malignant symptoms like allergy, asthma, rhinitis and chronic bronchitis have also been associated with occupational exposure to wood dust in epidemiological studies. In most epidemiological studies hardwoods (e.g. oak and beech wood dust) seems to have greater association to both the malignant and non-malignant symptoms compared to softwoods (e.g. pine and spruce wood dust). Since, well standardized experiments of wood dust exposure are limited and difficult to execute in humans, knowledge of the cellular mechanisms underlying wood dust induced carcinogenicity and non-malignant symptoms are still poorly understood. Particulate induced inflammation as well as extractives are suggested to be involved in the carcinogenesis. In this thesis wood dust potential to induce DNA damage and inflammation was investigated exposing the human lung epithelial cell line A549 to various species of wood dust and endpoints for inflammation and genotoxicity was evaluated. The experiments showed that the different species of wood dust vary in their ability to cause DNA strand breaks and inflammation. There was no apparent correlation between the species potential to initiate inflammation and their potential to cause DNA damage. Contrary to our hypothesis, we showed that pure wood dust is able to cause primary DNA damage, independent of inflammation as well as hardwoods had no higher inflammatory or genotoxic potential than softwoods. To investigate the molecular mechanisms behind the wood dust induced carcinogenesis, we examined human sinonasal tumours for mutations in the ras genes. The mutational spectrum, which is the type, site and frequency of mutations, provides useful clues to etiological factors and identification of exposure related tumours .We examined all incident cases of sinonasal adenocarcinoma and squamous cell carcinoma reported to the Danish Cancer Registry between 1991 and 2001. After a very careful inclusion process in order only to include sinonasal cancer of the nasal cavities and sinuses with correct histology, we included 174 cases. Wood dust exposure was assessed by interview and job/trade codes from the National Pension Fund and self reported job titles in the Central Personal Register. Among the cases wood dust exposure occurred in 21 percent of our patients and was 7 times more frequent in patients with adenocarcinomas than in squamous cell carcinoma (p<0.0001). In the mutational analysis, the K-ras gene was mutated in adenocarcinoma (13%) which is in the range reported in earlier studies, whereas the frequency was very low in the squamous cell carcinoma (1%). By analysis of all published K-ras mutations, the GGTGLY ¿GAT ASP transition was the most common K-ras codon 12 mutation. Despite that 65 percent of these patients had been exposed to wood dust, it was not significantly different from the patients without a G¿A mutation. The main conclusions based on the results obtained in this thesis are: All wood dust species cause inflammation. However, the species vary in their potential to induce the inflammation.Wood dust species vary in their potential to cause DNA damage. The DNA damage observed seemed to be caused by a direct genotoxic effect of the dust it selves.The current study provides evidence that the distinction between hard and softwoods dust may not be that clear cut in relation to health effects.The previously reported association between adenocarcinomas and exposure to wood dust could be confirmed by our study.Mutations activation of K-ras was restricted to a small subpopulation of the adenocarcinomas. The predominant mutations among these tumours were GC¿AT transitions.• Overall, the study suggests a limited role for K-ras mutations in development of sinonasal cancer.",

author = "Lange, {Jette Bornholdt}",

year = "2008",

language = "English",

publisher = "Museum Tusculanum",

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TY - BOOK

T1 - Effects of wood dust:Inflammation, Genotoxicity and Cancer.

AU - Lange, Jette Bornholdt

PY - 2008

Y1 - 2008

N2 - The present thesis focuses on the inflammatory, genotoxic and carcinogenic effects of exposure to different species of wood dust. The experimental work performed in this thesis consists of two parts. The first part of the study was carried out in an in vitro model with the human lung epithelial cell line A549 measuring inflammatory and DNA damaging effects. The second part consists of a molecular analysis of the K-ras gene for mutations in the hotspots codons in human sinonasal cancers. Design, calibration and validation of the assays were performed.Cancer at the sinonasal cavities is rare with incidence rates between of 0.3 to 1.4 per 100,000 for men and 0.1 to 0.8 per 100,000 for women in Europe, depending on country. However, cancer at this site is associated with occupational exposures including wood dust. Especially the adenocarcinoma subtype is strongly associated with exposure to wood dust primarily from hard woods. Non-malignant symptoms like allergy, asthma, rhinitis and chronic bronchitis have also been associated with occupational exposure to wood dust in epidemiological studies. In most epidemiological studies hardwoods (e.g. oak and beech wood dust) seems to have greater association to both the malignant and non-malignant symptoms compared to softwoods (e.g. pine and spruce wood dust). Since, well standardized experiments of wood dust exposure are limited and difficult to execute in humans, knowledge of the cellular mechanisms underlying wood dust induced carcinogenicity and non-malignant symptoms are still poorly understood. Particulate induced inflammation as well as extractives are suggested to be involved in the carcinogenesis. In this thesis wood dust potential to induce DNA damage and inflammation was investigated exposing the human lung epithelial cell line A549 to various species of wood dust and endpoints for inflammation and genotoxicity was evaluated. The experiments showed that the different species of wood dust vary in their ability to cause DNA strand breaks and inflammation. There was no apparent correlation between the species potential to initiate inflammation and their potential to cause DNA damage. Contrary to our hypothesis, we showed that pure wood dust is able to cause primary DNA damage, independent of inflammation as well as hardwoods had no higher inflammatory or genotoxic potential than softwoods. To investigate the molecular mechanisms behind the wood dust induced carcinogenesis, we examined human sinonasal tumours for mutations in the ras genes. The mutational spectrum, which is the type, site and frequency of mutations, provides useful clues to etiological factors and identification of exposure related tumours .We examined all incident cases of sinonasal adenocarcinoma and squamous cell carcinoma reported to the Danish Cancer Registry between 1991 and 2001. After a very careful inclusion process in order only to include sinonasal cancer of the nasal cavities and sinuses with correct histology, we included 174 cases. Wood dust exposure was assessed by interview and job/trade codes from the National Pension Fund and self reported job titles in the Central Personal Register. Among the cases wood dust exposure occurred in 21 percent of our patients and was 7 times more frequent in patients with adenocarcinomas than in squamous cell carcinoma (p<0.0001). In the mutational analysis, the K-ras gene was mutated in adenocarcinoma (13%) which is in the range reported in earlier studies, whereas the frequency was very low in the squamous cell carcinoma (1%). By analysis of all published K-ras mutations, the GGTGLY ¿GAT ASP transition was the most common K-ras codon 12 mutation. Despite that 65 percent of these patients had been exposed to wood dust, it was not significantly different from the patients without a G¿A mutation. The main conclusions based on the results obtained in this thesis are: All wood dust species cause inflammation. However, the species vary in their potential to induce the inflammation.Wood dust species vary in their potential to cause DNA damage. The DNA damage observed seemed to be caused by a direct genotoxic effect of the dust it selves.The current study provides evidence that the distinction between hard and softwoods dust may not be that clear cut in relation to health effects.The previously reported association between adenocarcinomas and exposure to wood dust could be confirmed by our study.Mutations activation of K-ras was restricted to a small subpopulation of the adenocarcinomas. The predominant mutations among these tumours were GC¿AT transitions.• Overall, the study suggests a limited role for K-ras mutations in development of sinonasal cancer.

AB - The present thesis focuses on the inflammatory, genotoxic and carcinogenic effects of exposure to different species of wood dust. The experimental work performed in this thesis consists of two parts. The first part of the study was carried out in an in vitro model with the human lung epithelial cell line A549 measuring inflammatory and DNA damaging effects. The second part consists of a molecular analysis of the K-ras gene for mutations in the hotspots codons in human sinonasal cancers. Design, calibration and validation of the assays were performed.Cancer at the sinonasal cavities is rare with incidence rates between of 0.3 to 1.4 per 100,000 for men and 0.1 to 0.8 per 100,000 for women in Europe, depending on country. However, cancer at this site is associated with occupational exposures including wood dust. Especially the adenocarcinoma subtype is strongly associated with exposure to wood dust primarily from hard woods. Non-malignant symptoms like allergy, asthma, rhinitis and chronic bronchitis have also been associated with occupational exposure to wood dust in epidemiological studies. In most epidemiological studies hardwoods (e.g. oak and beech wood dust) seems to have greater association to both the malignant and non-malignant symptoms compared to softwoods (e.g. pine and spruce wood dust). Since, well standardized experiments of wood dust exposure are limited and difficult to execute in humans, knowledge of the cellular mechanisms underlying wood dust induced carcinogenicity and non-malignant symptoms are still poorly understood. Particulate induced inflammation as well as extractives are suggested to be involved in the carcinogenesis. In this thesis wood dust potential to induce DNA damage and inflammation was investigated exposing the human lung epithelial cell line A549 to various species of wood dust and endpoints for inflammation and genotoxicity was evaluated. The experiments showed that the different species of wood dust vary in their ability to cause DNA strand breaks and inflammation. There was no apparent correlation between the species potential to initiate inflammation and their potential to cause DNA damage. Contrary to our hypothesis, we showed that pure wood dust is able to cause primary DNA damage, independent of inflammation as well as hardwoods had no higher inflammatory or genotoxic potential than softwoods. To investigate the molecular mechanisms behind the wood dust induced carcinogenesis, we examined human sinonasal tumours for mutations in the ras genes. The mutational spectrum, which is the type, site and frequency of mutations, provides useful clues to etiological factors and identification of exposure related tumours .We examined all incident cases of sinonasal adenocarcinoma and squamous cell carcinoma reported to the Danish Cancer Registry between 1991 and 2001. After a very careful inclusion process in order only to include sinonasal cancer of the nasal cavities and sinuses with correct histology, we included 174 cases. Wood dust exposure was assessed by interview and job/trade codes from the National Pension Fund and self reported job titles in the Central Personal Register. Among the cases wood dust exposure occurred in 21 percent of our patients and was 7 times more frequent in patients with adenocarcinomas than in squamous cell carcinoma (p<0.0001). In the mutational analysis, the K-ras gene was mutated in adenocarcinoma (13%) which is in the range reported in earlier studies, whereas the frequency was very low in the squamous cell carcinoma (1%). By analysis of all published K-ras mutations, the GGTGLY ¿GAT ASP transition was the most common K-ras codon 12 mutation. Despite that 65 percent of these patients had been exposed to wood dust, it was not significantly different from the patients without a G¿A mutation. The main conclusions based on the results obtained in this thesis are: All wood dust species cause inflammation. However, the species vary in their potential to induce the inflammation.Wood dust species vary in their potential to cause DNA damage. The DNA damage observed seemed to be caused by a direct genotoxic effect of the dust it selves.The current study provides evidence that the distinction between hard and softwoods dust may not be that clear cut in relation to health effects.The previously reported association between adenocarcinomas and exposure to wood dust could be confirmed by our study.Mutations activation of K-ras was restricted to a small subpopulation of the adenocarcinomas. The predominant mutations among these tumours were GC¿AT transitions.• Overall, the study suggests a limited role for K-ras mutations in development of sinonasal cancer.

M3 - Ph.D. thesis

BT - Effects of wood dust:Inflammation, Genotoxicity and Cancer.

PB - Museum Tusculanum

ER -

Effects of wood dust:Inflammation, Genotoxicity and Cancer.

Abstract

FN’s Verdensmål

Fingeraftryk

Citationsformater