A Novel Antigen Associated with Breast Cancer Metastasis

Institution: Sidney Kimmel Cancer Center
Investigator(s): Jacqueline Testa, Ph.D. -
Award Cycle: 2000 (Cycle VI) Grant #: 6IB-0012 Award: $135,132
Award Type: IDEA
Research Priorities
Biology of the Breast Cell>Pathogenesis: understanding the disease



Initial Award Abstract (2000)
Metastasis, the process whereby tumor cells spread throughout the body, is the leading cause of death in breast cancer patients but the reasons why tumor cells spread are not clearly understood. The purpose of this project is to identify a new protein that plays an important role in the spread of breast cancer cells. This protein was first detected by a molecule called a monoclonal antibody. This monoclonal antibody, named mAb 41-2, was produced in the laboratory using a technique called subtractive immunization. This technique allowed us to produce monoclonal antibodies that can bind to cancer cell proteins that are involved in tumor cell spread and block their function. We have discovered that the protein recognized by mAb 41-2 is present in several breast tumor cell lines and present at higher amounts in metastatic breast cancer cells when compared to normal breast cells. Additionally, our laboratory experiments show that mAb 41-2 blocks invasion of metastatic breast cancer cells. In analyzing the composition of this protein, we have discovered that it is a new protein that has not yet been cloned. Therefore, in our present application, we propose to clone the protein. This information will help us to determine what type of protein it is and may also provide clues as to how it functions in the spread of breast tumor cells. We will also determine how much of this protein is found in biopsies from different stages of breast cancer, which will help us determine if this protein correlates with tumor stage, grade, and with patient outcome. If successful, we will identify a new protein associated with breast cancer metastasis and will acquire new insight into the cellular events that lead to the spread of cancer.


Final Report (2002)
Metastasis, the process whereby tumor cells spread throughout the body, is the leading cause of death in cancer patients. In California, breast cancer is the most frequently diagnosed cancer in women and the second leading cause of death. The reasons why tumor cells spread are not clearly understood.

The purpose of this project was to identify a new protein that plays an important role in the spread of breast cancer cells. The protein was first detected by a molecule called a monoclonal antibody named mAb 41-2. This antibody can bind to cancer cell proteins that are involved in tumor cell spread and can block metastasis in our laboratory assays. We have discovered that the protein recognized by mAb 41-2 is present at higher levels in metastatic breast cancer cells when compared to normal breast cells. In our laboratory experiments, mAb 41-2 blocks invasion of metastatic breast cancer cells. In analyzing the composition of this protein, we have discovered that it has not previously been found by anyone else.

We have successfully cloned a cDNA that encodes a protein recognized by mAb 41-2. When this cDNA is introduced into cells, the protein appears in its proper location on the cell surface. The cloned DNA is being sequenced and assembled with the aid of a computer. Analysis of the amino acid building blocks that make up the protein will help us to determine what type of protein it is and may also proved clues as to how it functions in the spread of breast tumor cells.

mAb 41-2 will not work on paraffin-embedded tissues and must, therefore, be used on fresh frozen sections. Samples were more difficult to obtain than had been anticipated. After termination of the present grant, we received a total of 12 human breast tumor biopsies from the Cooperative Human Tissue Network (CHTN) and matched adjacent normal breast tissue for five of the samples. Unfortunately, not all stages of breast cancer are represented in these samples and we are unable, at this point, to determine if there is a correlation between this protein and breast cancer progression. Using the information from the analysis of the amino acid sequence of our protein, we are developing new antibodies that can be used on paraffin-embedded tissues. These antibodies will allow us to screen a large number of paraffin-embedded breast biopsies, which are readily available.

Our work has identified a new protein that is functionally involved in tumor cell dissemination. Identification of new markers of breast cancer progression, and the development of new treatments for metastatic disease are essential objectives. Antibodies to these new markers may be useful as diagnostic tools, or as imaging agents, or even as reagents with which to specifically deliver drugs of gene therapies.