The Mary Lasker Conference, on growth factors in hormone-related tumors.

The Mary Lasker Conferences, sponsored by the American Cancer Society, have the goal of sharing information in a critical cancer research field. The Lasker Conference held in December 1989 focused on the subject of Growth Factors in Hormonerelated Tumors and was initiated because of rapid progress in the understanding of growth factors, growth factor receptors, hormone action, and oncogenes. The American Cancer Society brought together leaders in this field to see if current knowledge had opened any new routes to the control or therapy of hor mone-related tumors in humans. If not, the organizers chal lenged the workshop participants to identify the research areas that will provide the knowledge necessary for progress toward these goals. Participants were requested to bring their knowledge of growth factors, hormones, and differentiating agents related to three main areas: how those substances influence the processes of cell replication and differentiation; how they influence the expression of cell cycle-dependent genes and the assembly of G i interval protein complexes that, as defined in lower cell systems, play an intrinsic role in the G, to S-phase transition of the cell cycle; and how they influence the mechanisms that lead to cell replication or to terminal differentiation or cell death in these tumors. One must note that the replication frequency of mammalian cells is largely controlled by molecular events that occur in the G, interval of the cell cycle. Whether it is the impact of a growth factor, a hormone, or a unique nutrient, the response is usually one of activating a receptor which in turn activates a chain of reactions that culminates in the triggering of S-phase and DNA/ chromatin replication. This trigger appears to involve the acti vation of genes leading to the synthesis and assembly of the DNA replicase system. While our knowledge of this chain of reactions is still fragmentary for mammalian cells, studies of the cell cycle in yeast and oocyte systems have unearthed certain genes and gene products that are essential to this progression. While knowledge of the molecular events regulating the triggering of cell replication is essential in order to deal with the human problem of hormone-related tumors, it is equally important to understand the processes that lead to terminal differentiation or cell death in these tumors. An oncogenic event leading to a growth advantage and tumorigenesis fre quently leaves the cell with a normal complement of processes for terminal differentiation. The challenge to the therapist is to find ways to superinduce these vestigial potentials. Success in this endeavor could spell the ultimate in selective therapy of cancer.