[p53 gene mutation in cancer of the colon and rectum].
BACKGROUND
Genetic events associated to colorectal carcinoma are well characterized, but there is scanty information about this issue in Chilean subjects.


OBJECTIVE
To determine the frequency and distribution of exons 5, 6, 7, 8 and 9 mutations and the immunohistochemical expression of p53 gene in biopsy samples of colorectal carcinoma.


METHODS
p53 gene exons 5, 6, 7, 8 and 9 were directly sequenced in 42 biopsy samples of colorectal carcinoma. Immunohistochemical expression of p53 was determined in 35 samples.


RESULTS
Thirty one discrete mutations (12 transitions, 11 transversions and 8 insertions) were observed in 21 samples (60%). Nine samples had mutations in exon 5, twelve samples had mutations in exon 6, seven samples had mutations in exon 7 and three samples had mutations in exons 8 and 9. Immunohistochemical expression of p53 protein was observed in 18 of 35 cases. There was a high correlation between the genetic alteration and immunohistochemistry, when p53 was expressed in more the 20% of cells. The positive and negative predictive values of p53 expression were 87 and 80% respectively. There was a non significant lower mortality among patients with mutations in their biopsies.


CONCLUSIONS
These results confirm the involvement of p53 gene mutations in colonic carcinogenesis. Immunohistochemical methods for the detection of p53 protein have a high predictive value.
Roa
J C
JC
Unidad de Anatomía Patológica, Servicio y Departamento de Cirugía, Hospital de Temuco., Facultad de Medicina, Universidad de la Frontera, Temuco, Chile.
Roa
I
I
Melo
A
A
Araya
J C
JC
Villaseca
M A
MA
Flores
M
M
Schneider
B
B
D000230:Adenocarcinoma / Q000235:genetics*; D000328:Adult; D003110:Colonic Neoplasms / Q000235:genetics*; D005091:Exons / Q000235:genetics; D005260:Female; D005787:Gene Frequency; D016158:Genes, p53 / Q000235:genetics*; D006801:Humans; D008297:Male; D009154:Mutation / Q000235:genetics*; D016133:Polymerase Chain Reaction; D011237:Predictive Value of Tests; D012004:Rectal Neoplasms / Q000235:genetics*; D016019:Survival Analysis; D016159:Tumor Suppressor Protein p53 / Q000737:chemistry / Q000302:isolation & purification*
D016159:Tumor Suppressor Protein p53