Effect on in vivo tumorigenicity of lengthy exposure of human colon cancer cells to the differentiation agent hexamethylene bisacetamide.

The heterogeneity of tumor responses to maturation agents was studied using the multi-potential, non-cloned human colon carcinoma cell line HT29. Short-term treatment (5 cell doublings) with the differentiation agent hexamethylene bisacetamide (HMBA) induced a sharp decrease in tumorigenicity in vivo and loss of a cell surface malignancy marker. However, prolonged treatment (22 cell doublings) with the agent lead to loss of the HMBA-sensitive subpopulation from the mass culture, and enrichment of a tumorigenic, HMBA-resistant subpopulation.