[Application of immunohistochemistry-laser microdissection-PCR technique in detecting p53 gene mutation in paraffin sections of gastric cancer].

Objective: To evaluate the application of immunohistochemistry-laser microdissection-polymerase chain reaction (IHC-LMD-PCR) technique in detecting p53 gene mutations using paraffin sections of advanced gastric cancers.

Methods: The expression of p53 protein in 41 paraffin-embedded advanced gastric cancer samples was assessed by immunohistochemistry. The p53-positive or negative carcinoma cells and normal foveolar cells far from the main tumor were then isolated by LMD. The DNA was extracted and p53 gene at exon 5 - 8 amplified by PCR. The products were then analyzed by single-strand conformation polymorphism (SSCP) and automated sequencing.

Results: p53 gene was successfully amplified in all the 41 specimens. Overexpression of p53 protein was noted in 11 cases. Mutations of p53 gene were found in 15 cases. Eight of the 11 p53-overexpressed cases had p53 gene mutations. On the other hand, p53 gene mutations were found in only 7 of the 30 p53 protein-negative cases. The presence of p53 gene mutations significantly correlated with p53 protein overexpression (P = 0.004).

Conclusions: IHC-LMD-PCR technique can be successfully applied in paraffin sections of gastric cancers for the detection of p53 gene mutations. The results correlate well with overexpression of p53 protein.