Sonic hedgehog expression in gastric cancer and gastric adenoma

Hedgehog protein is essential to gastrointestinal tract development, and disruption of the hedgehog signaling pathway is associated with gastrointestinal tumorigenesis. Here, we analyzed the degree of hedgehog expression in gastric cancer and precancerous tissue. From August 2005 to May 2006, 52 gastric cancers and 16 gastric adenomas were obtained from surgically or endoscopically resected specimens. Immunohistochemical staining using sonic hedgehog (Shh) antibody was performed in cancerous and noncancerous tissue portions. Hedgehog expression was assessed based on the summed scores of the intensity and proportion of Shh staining. According to Lauren's classification, Shh expression was stronger in the intestinal type than in the diffuse type (p<0.001). Although Shh expression was not related to the location, size, metastatic status, or mucin phenotype of the gastric cancer, the expression was stronger in the tubular type of gastric cancer than in the mucinous and signet-ring cell types (p=0.001). Shh expression was stronger in gastric adenoma than in the diffuse-type gastric cancer (p<0.001), but revealed no difference with that of the intestinal-type gastric cancer (p=0.30). Shh expression was strongest in all types of intestinal metaplasia of noncancerous tissues. Shh expression is related to the intestinal type of gastric cancer. The stronger Shh expression in intestinal metaplasia and gastric adenoma indicates that hedgehog protein is involved at an early phase of gastric carcinogenesis.