The insulin-like growth factors I and II (IGF-I and -II) are proteins which stimulate cell proliferation and are important in normal human growth and development. They are coded for by separate genes and bind to specific cell surface receptors, eliciting a mitogenic response. IGFs are secreted by several cell lines derived from adult tumors. We have examined a number of human adult tumors for IGF messenger RNA (mRNA) expression and found IGF-II mRNA levels were consistently elevated in two types, colon carcinoma and liposarcoma. Adult colonic mucosa contains low levels of IGF-I and -II mRNA while several colon tumors, particularly of rectal and rectosigmoid origin, contained significantly elevated levels of IGF-II message. Over 90% of liposarcomas examined contained greatly elevated levels of IGF-II mRNA while control tissue (adipose) contained very low or undetectable IGF mRNA levels. Many of these tumors also contained elevated IGF-I mRNA levels. Northern analysis of these RNAs revealed differences in the abundance and sizes of IGF transcripts compared to other normal and malignant tissues known to express IGF.


This investigation was supported by American Cancer Society grant CD-62 and NIH grants GM-20454 and CA28853.

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