Molecular and Cell Biology Laboratory
Walter Eckhart served as director of the Salk Institute Cancer Center and head of the Molecular and Cell Biology Laboratory for more than 30 years. He studied regulation of cell growth, including the effects of cancer-causing genes (oncogenes), growth factors, and communication between adjacent cells (gap junctional intercellular communication). Currently professor emeritus at the Salk Institute, he is a member of advisory committees for cancer centers, the National Institutes of Health, and voluntary health agencies.
The growth of cells is tightly controlled, but cancer cells turn a deaf ear to signals that cause normal cells to stop dividing. Eckhart identified and characterized genes in tumor viruses—so-called viral oncogenes—that override normal cell cycle controls. The viral genes he studied stimulate cellular growth signaling pathways, allowing the cells to divide continuously. Identification of growth signaling pathways has led to the development of drugs that inhibit the growth of cancer cells.
Cancer cells also lose the ability to communicate with each other through the exchange of materials through channels called gap junctions. This communication is important for coordinating the activities of cells in tissues, including normal regulation of cell growth. The proteins that form the channels are called connexins. Eckhart found that some cancer-causing genes modify connexins, thereby shutting off communication between adjacent cells and disrupting normal growth. Restoration of communication allows the cells to grow normally again, suggesting that agents that regulate cellular communication might help in reversing cancer. Eckhart also studied the effects of a growth factor, insulin-like growth factor-1 (IGF-1), on human mammary epithelial cells growing in a threedimensional culture system that mimics the environment of the body. Abnormal signaling by IGF-1 stimulated changes in the growth properties of the cells, similar to changes that happen during early tumor development. Studies like these are helping to define how changes in genes and growth signaling can lead to breast cancer.
Eckhart served as director of the Salk Institute Cancer Center and head of the Molecular and Cell Biology Laboratory for more than 30 years. He phased out his laboratory research program and became professor emeritus in 2010. He presently serves on advisory committees for cancer centers, the National Institutes of Health and voluntary health agencies.