nm23-H1 protein immunoreactivity in laryngeal carcinoma

The nm23-H1 gene encodes a 17-kilodalton cytoplasmic and nuclear protein that has recently been shown to be reduced in a number of human carcinomas including breast, colorectal, lung, gallbladder, and biliary tract carcinomas. This study examines the immunohistochemical staining characteristics of the nm23-H1 protein in human laryngeal carcinomas and nonneoplastic laryngeal polyps, and attempts to determine if there is any relationship between reduction of nm23-H1 protein immunoreactivity and prognosis of patients with laryngeal carcinoma.

Routine streptavidin-biotin immunohistochemistry with a polyclonal antibody was employed to study the expression of the nm23-H1 protein in laryngeal squamous cell carcinoma (SCC) (N = 22) and nonneoplastic polyps (N = 8). The carcinomas were classified as well differentiated (N = 2), moderately differentiated (N =15), and poorly differentiated (N = 5). Tissues from metastatic tumor deposits in lymph nodes (N = 5) were also studied. A semiquantitative immunostaining index was derived from the intensity and extent of staining of the cells.

All laryngeal polyps showed intense immunostaining for the nm23-H1 gene product in the squamous epithelium. However, reduced immunoreactivity was found in nearly half of the SCC cases (N = 10; 46%), with the least staining intensity found in tumor metastases in lymph nodes (N = 4; 80%), and were associated with a shorter median survival of 14.3 months. In contrast, tumors that demonstrated moderate to strong nm23-H1 protein immunostaining were associated with a longer median survival period of 20.4 months.

There is reduced expression of the nm23-H1 gene in human laryngeal SCC compared with nonneoplastic laryngeal polyps. Reduction in the intensity and extent of nm23-H1 protein immunostaining appears to correspond to reduced duration of patients survival.