Functional Analysis of BORIS, A Novel DNA-binding Protein

Institution: Lawrence Berkeley National Laboratory
Investigator(s): Paul Yaswen, Ph.D. -
Award Cycle: 2003 (Cycle IX) Grant #: 9WB-0193 Award: $92,426
Award Type: STEP Award
Research Priorities
Biology of the Breast Cell>Biology of the Normal Breast: the starting point



Initial Award Abstract (2003)
Abundant evidence supports the theory that cancer progression is driven by mutations of specific genes and their aberrant or inappropriate biochemical functions. Numerous laboratories, including ours, are exploring the normal and abnormal functions of genes frequently found to be altered in breast cancer cells in the belief that better understanding of these functions will help us to design less toxic and more efficacious therapies, and preventative regimens. Our laboratory has pioneered the development and use of cultured human mammary epithelial cells (HMEC), the cell type from which most breast cancers originate. We use this system as an experimental model to gain information about how genetic changes lead to the deregulated growth, survival, and invasive properties (transformation) that are the defining features of breast cancer.

Recently a new gene has been identified that corresponds to a region of chromosome 20 that frequently undergoes mutations in a high proportion of breast cancers, and is believed to be the site of one or more uncharacterized oncogenes (cancer genes). This gene, BORIS, is normally only used in specific cells in human testes where it aids in the production of sperm. When used inappropriately, as it is in many breast cancer cells, the BORIS gene may produce a protein that interferes with the ability of another protein, CTCF, to suppress unlimited growth and tumor formation. Our studies are intended to determine exactly what functions are altered in BORIS-expressing cells, and how these altered functions might contribute to cancer progression.

We will use our well-characterized HMEC culture system to determine precisely when, during the course of early transition to cancer, HMEC start to aberrantly use the BORIS gene to make protein, and correlate this timing with other key events. To determine directly whether BORIS is an oncogene which actually causes transformation on its own or in concert with other changes, we will artificially engineer HMEC from normal breast tissue to make BORIS protein and/or other oncogene products. We will then subject these and control cells to tests for transformation-related changes, such as the ability to divide and make more cells indefinitely. The results of these tests will enable us to determine what biochemical pathways are disrupted by the aberrant presence of BORIS protein, and how this may contribute to human breast cancer progression.

Our unique HMEC culture system allows us to study a) cellular responses to specific changes under conditions where other potential variables are controlled, and b) characteristics that may be uniquely human and thus not amenable to study using animal models. Moreover, the system uses cells, derived from normal breast tissue, which have not undergone changes often seen in immortal cells or cells derived from tumors, which might complicate the analysis of putative oncogenes.