Nm23 gene expression in gastric carcinoma: An immunohistochemical study

Background: The gene Nm23 is thought to play a role in the suppression of tumour metastasis. Reduced expression of Nm23 is seen in a number of human cancers, and is associated with increased metastasis and reduced survival, most strongly in ductal breast an colorectal carcinomas. Methods: Nm23 gene expression was compared in gastric carcinoma and normal gastric mucosa. Twenty- three gastric carcinoma were graded for differentiation as either well, moderately or poorly differentiated. Metastatic deposits from seven of the cases were also examined, along with 10 samples of normal gastric mucosa. Specimens were incubated with a murine monoclonal antibody against the protein product of Nm23, and examined by immunohistochemical staining. A semiquantitative immunostaining index was used. Results: All normal mucosa showed moderate to strong staining; 8 of 15 poorly differentiated carcinomas showed absent or weak staining; 1 of 6 moderately differentiated carcinomas stained weakly. Both well- differentiated carcinomas stained strongly; 1 of 7 metastatic deposits stained weakly. The difference in Nm23 expression between normal mucosa and carcinomas was statistically significant (P = 0.024). However, there was no statistically significant difference between the three grades of carcinomas (P = 0.51), or between primary and metastatic tumour (P = 0.25, all by Chi-squared test). Conclusions: These results suggest that Nm23 may have a role in gastric carcinoma pathogenesis, but do not show a correlation with metastasis. A larger study, involving detailed clinical staging and follow-up, may be of benefit.