Expression of insulin-like growth factor 2 mRNA in human gastric cancer

Insulin-like growth factor 2 (IGF2) stimulates cell proliferation and development in normal human growth. In several human cancers, the IGF2 gene is overexpressed and is thus considered to be a growth factor for tumors mediated through both the paracrine and autocrine pathways. However, the significance of IGF2 mRNA expression in gastric cancer has yet to be clarified. We semi-quantitatively measured the expression of IGF2 mRNA in 57 Japanese cases of gastric cancer by means of the reverse transcription polymerase chain reaction and also analyzed the relation between the IGF2 expression status and other clinicopathologic factors. We also performed immunohistochemical staining for IGF2. In 41 of 57 cases (72%), the expression of IGF2 mRNA was greater in tumor tissue (T) than in normal tissue (N). The average tumor/normal (T/N) expression ratio of IGF2 mRNA corrected for that of control gene mRNA was 1.42, while ranging from 0.36 to 3.65. The T/N ratio of infiltrative-type cancers was greater than that of expanding- type cancers (p<0.05). The cases with lymphatic permeation showed a greater T/N ratio than those without lymphatic permeation in expanding-type cancers (p<0.05). Immunohistochemical staining revealed IGF2 to be detected in cancer cells themselves, especially at the margin of the cancer tissue. The IGF2 gene may thus play an important role in lymph vessel permeation especially in expanding-type gastric cancers.