Autocrine stimulation in colorectal carcinoma (CRC): positive autocrine loops in human colorectal carcinoma and applicable significance of blocking the loops.

Many tumors co-express growth factors and their receptors; thus, the concept of autocrine secretion was proposed to explain the unrestrained growth of the malignant cells. Autocrine stimulation refers to positive autocrine secretion, which functions to stimulate cell growth. Many of the positive autocrine loops have been demonstrated in human colorectal carcinoma (CRC), which are considered to play an important role in the initiation and progression of the cancer. These autocrine loops provide information for prognostic markers and targets for biological therapies of CRC. Interruption of the autocrine loops could potentially inhibit malignant cell growth. The field is encouraging but further research is needed.