[Gene methylation patterns in digestive tumors].
BACKGROUND
The loss of tumor suppressor gene function damages the defensive mechanisms that protect the indemnity of genetic material. Promoter gene methylation is one of the inactivation mechanisms of suppressor genes.


OBJECTIVE
To study the methylation pattern of a group of genes in biopsy samples of gastrointestinal tumors.


METHODS
Forty eight gastric, 25 gallbladder, 24 colon and 6 pancreas cancer biopsy samples were randomly selected. The methylation pattern of CDH1, FHIT, CDKN2A, APC and MLH1 genes, was studied using a specific polymerase chain reaction test for methylation. Demographic, morphological and follow up variables of patients bearing the tumors were also analyzed.


RESULTS
The general methylation frequency of CDH1, FHIT, CDKN2A, APC and MLH1 genes was 64.1, 56, 39.8, 18.1 and 34% respectively. In gastric cancer samples there was a correlation between APC gene methylation and well differentiated tumors; between CDH1 methylation and Lauren diffuse type and the presence of three or more metastasic lymph nodes; between FHIT, CDKN2A and CDH1 gene methylation and male gender. In less differentiated gallbladder tumors, the frequency of CDH1 methylation was higher. There was a tendency towards a lower survival in colon and gastric cancer when MLH1 (p =0.07) y CDKN2A (p= 0.06) were methylated, respectively.


CONCLUSIONS
An abnormal methylation pattern was associated with morphological features in gastric and gallbladder cancer and with a tendency towards a lower survival in colon and gastric cancer.
Roa S
Juan Carlos
JC
Laboratorio de Patología Molecular, Departamento de Anatomía Patología, Facultad de Medicina, Universidad de La Frontera, Temuco, Chile. lcroa@ufro.cl
García M
Patricia
P
Melo A
Angélica
A
Tapia E
Oscar
O
Villaseca H
Miguel
M
Araya O
Juan Carlos
JC
Guzmán G
Pablo
P