Effect of serum in the growth medium on mucin synthesis by colon cancer cell line.

A positive correlation has been described between mucin synthesis, tumorigenicity, and a poor prognosis in human colorectal cancer. Serum growth factors and hormones have been implicated in the regulation of biological behavior of the neoplasm, including growth and differentiation. Growth and differentiation of cancer cells have been observed to be involved in altered expression of mucin mRNA and synthesis. In the present study, the relationship between serum growth factors and mucin synthesis was studied in LS174T colon cancer cells grown in medium with different serum concentrations, and with 20% serum that was heated to 80 degrees C for 60 min or dialysed against saline. Mucin synthesis was estimated by measuring the amount of [3H]glucosamine-labeled glycoprotein excluded on a Sepharose CL-4B column. When the cells were compared on the basis of the same cell number, the higher the serum concentration of the medium, the more mucin produced. There was no decrease in mucin production after heating or after dialysis, indicating that there is a heat-stable non-dializable serum factor which induces mucin synthesis.