Immunohistochemical expression of nm23 gene product, nucleotide diphosphate kinase, in pancreatic neoplasms.

CONCLUSION

Our findings suggest that contrary to the proposed role for the nm23 protein as a tumor metastasis suppressor, in pancreatic tumors, the nm23 protein does not play an important role as a suppressor against tumor metastasis.

BACKGROUND

The nm23 gene product, nucleotide diphosphate kinase, is believed to suppress tumor metastasis. Although a number of studies on many kinds of tumors have examined the relationship between nm23 expression and metastatic potential, the antimetastatic activity of nm23 remains controversial. The expression of the nm23 protein has not been examined in pancreatic tumors, except for a few reports on pancreatic duct cell carcinomas.

METHODS

We have investigated nm23 expression in pancreatic duct cell carcinomas, islet cell tumors, and ampullary carcinomas by immunohistochemical methods.

RESULTS

In 73 cases of pancreatic duct cell carcinomas, the nm23 expression was increased when compared with the adjacent normal pancreatic ducts; diffuse immunostaining was detected in 21 (29%) cases, focally positive immunostaining in 47 (64%) cases, and negative immunostaining in 5 cases (7%). All five negative samples were obtained from distant metastatic regions. However, there was no significant difference in the nm23 expression between primary tumors and regional lymph node metastases. Furthermore, there was no significant correlation between nm23 expression and the prognosis of the 55 resected cases. In the 15 cases of ampullary carcinomas, all 15 tumors were positive for nm23 protein (6 diffuse and 9 focal), and the staining intensity was stronger than in normal pancreatic ducts. There was no significant difference in the nm23 expression in the primary regions between patients with and without lymph node metastasis (2 diffuse and 5 focal out of 7 patients with lymph node metastasis, and 4 diffuse and 4 focal out of 8 patients without lymph node metastasis). All 12 islet cell tumors showed strong and diffuse staining for the nm23 protein.