Beta-chemokine, macrophage inflammatory protein-1beta (MIP-1beta), is highly expressed in diffuse type human gastric cancers.

Chemokines have been shown to be expressed in some malignant or precancerous tissues. However, the role of these chemokines on tumor development or progression is not clear. The expression patterns of chemokines in gastric cancer tissues were examined in 86 surgically resected samples using immunohistochemistry. Macrophage inflammatory protein-1beta (MIP-1beta) was clearly detected in many gastric carcinoma cells. In most of the differentiated carcinomas, intracellular localization of MIP-1beta was detected in more than 5% of cancer cells, although the percentages of MIP-1beta-positive cells differed among each sample. Undifferentiated carcinomas showed contrasted staining pattern between solid type and non-solid (diffuse) type. MIP-1beta was totally absent in all the poorly differentiated carcinomas with solid type growth pattern (por1). In contrast, MIP-1beta was highly expressed in all of the non-solid type of poorly differentiated carcinoma (por2) and signet-ring cell carcinoma samples. In particular, MIP-1beta was strongly stained in carcinoma cells at the front of invasive lesions. In 43 diffuse type undifferentiated cancers, tumors with high expression of MIP-1beta exhibited significantly more lymph node metastasis. Our results suggest a possibility that MIP-1beta may be related to the scattering and invasion step of gastric carcinoma cells with undifferentiated phenotype.