This chapter focuses on the role of major positive and negative autocrine loops in maintaining growth regulation in colon cancer and the mechanisms underlying the breakdowns in these autocrine loops that lead to growth factor independence in this system. While the details in this chapter and the specific autocrine loops described deal with colon cancer, the general principles of growth factor dependence and the role of the balance of positive and negative controls in maintaining growth factor dependence should be applicable to other systems. Growth factor dependence and unaggressive biological behavior as evidenced by reduced tumorigenicity is tightly coupled to the expression of a transforming growth factor-β (TGF-β) autocrine loop. The TGF-β autocrine loop maintains cells in a quiescent or nondividing state in the absence of exogenous growth factor stimulation. One way in which it carries out this function out is by repressing TGF-α expression.
All Science Journal Classification (ASJC) codes
- Molecular Biology
- Cell Biology