Repair genes expression profile of MLH1, MSH2 and ATM in the normal oral mucosa of chronic smokers.
OBJECTIVE
The aim of this study was to evaluate the effect of chronic smoking on the expression profile of the repair genes MLH1, MSH2 and ATM in the normal oral mucosa of chronic smokers and never smokers.


METHODS
The sample consisted of thirty exfoliative cytology smears per group obtained from Smokers and Never Smokers. Total RNA was extracted and expression of the MLH1, MSH2 and ATM genes were evaluated by quantitative real-time and immunocytochemistry. The gene and protein expression data were correlated to the clinical data. Gene expression was analyzed statistically using the Student t-test and Pearson's correlation coefficient, with p<0.05.


RESULTS
MLH1, MSH2 and ATM genes were downregulated in the smoking group compared to the control with significant values for MLH1 (p=0.006), MSH2 (p=0.0001) and ATM (p=0.0001). Immunocytochemical staining for anti-MLH1, anti-MSH2 and anti-ATM was negative in Never Smokers; in Smokers it was rarely positive. No significant correlation was observed among the expression of MLH1, MSH2, ATM and age, number of cigarettes consumed per day, time of smoking during life, smoking history or levels of CO in expired air.


CONCLUSIONS
The expression of genes and proteins related to DNA repair mechanism MLH1, MSH2 and ATM in the normal oral mucosa of chronic smokers was reduced.
Department of Biosciences and Oral Diagnosis, Institute of Science and Technology, UNESP - Univ Estadual Paulista, São José dos Campos, São Paulo, Brazil; School of Dentistry, Universidade Braz Cubas, Mogi das Cruzes, Brazil. Electronic address: mgoliveiraalves@gmail.com.
Mônica Ghislaine Oliveira
MG
Alves
Department of Biosciences and Oral Diagnosis, Institute of Science and Technology, UNESP - Univ Estadual Paulista, São José dos Campos, São Paulo, Brazil.
Celina Faig Lima
CF
Carta
Department of Biosciences and Oral Diagnosis, Institute of Science and Technology, UNESP - Univ Estadual Paulista, São José dos Campos, São Paulo, Brazil.
Patrícia Pimentel
PP
de Barros
Smoking Cessation Program, Area of Cardiology, Heart Institute, University of São Paulo School of Medicine, Hospital das Clínicas, São Paulo, Brazil.
Jaqueline Scholz
JS
Issa
Department of Oral Pathology, School of Dentistry, University of São Paulo, São Paulo, São Paulo, Brazil.
Fábio Daumas
FD
Nunes
Department of Biosciences and Oral Diagnosis, Institute of Science and Technology, UNESP - Univ Estadual Paulista, São José dos Campos, São Paulo, Brazil.
Janete Dias
JD
Almeida
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D064007:Ataxia Telangiectasia Mutated Proteins / Q000235:genetics* / Q000378:metabolism; D004260:DNA Repair; D015536:Down-Regulation; D015870:Gene Expression; D006801:Humans; D007150:Immunohistochemistry; D008875:Middle Aged; D009061:Mouth Mucosa / Q000378:metabolism*; D000070957:MutL Protein Homolog 1 / Q000235:genetics* / Q000378:metabolism; D051718:MutS Homolog 2 Protein / Q000235:genetics* / Q000378:metabolism; D012907:Smoking
C501486:MLH1 protein, human; C576324:ATM protein, human; D064007:Ataxia Telangiectasia Mutated Proteins; C497172:MSH2 protein, human; D000070957:MutL Protein Homolog 1; D051718:MutS Homolog 2 Protein
Carcinoma; Gene expression immunocytochemistry; Smoking; Squamous cell