Breast cancer is a heterogeneous disease that can be subclassified into several tumor types. Inflammatory breast cancer (IBC) is the most aggressive form of breast cancer. IBC is a locally advanced breast cancer that affects women at an earlier age than other types of breast carcinoma. The disease is characterized by a high tumor microvessel density, fast disease progression, and by extremely poor survival. Although the frequency of IBC among breast cancer cases in the US is only 3-5%, it appears to be much more common in other geographic areas, such as North Africa. The causes of IBC are unknown and both environmental and genetic risk factors are thought to be involved. The early onset of the disease, the strong angiogenicity and propensity of IBC to invade vessels, and the large disparity in the IBC incidence among various populations are indicators of genetic predisposition and inherited susceptibility. Both low- and high-risk cancer susceptibility genes may determine the risk for IBC. Two genes, WISP3 and RhoC GTPase, have recently been identified that are differently expressed in IBC when compared with non-IBC breast cancer. WISP3 is a putative tumor suppressor gene for the disease, and may regulate the insulin-like growth factor pathway. RhoC GTPase is an overexpressed oncogene in IBC, and modulates the induction of angiogenic factors in breast cells. As part of our ongoing breast cancer case-control study, we collected seven specimens from inflammatory breast cancer (IBC) patients, 20 specimens from non-IBC breast cancer patients with poor survival and 20 specimens from non-IBC breast cancer patients with good survival. Serial sections of OCT-fixed tissues have been prepared from the 47 fresh-frozen tumors, and ten normal breast tissues from breast reduction surgery. The first slide of the serial sections has been formalin-fixed and stained with hematoxylin and eosin to identify tumor and surrounding normal tissue. The slides have been reviewed by a pathologist for the presence of tumor cells. The sections are currently being microdissected. We hypothesize that IBC has a distinct expression profile in tumor and normal surrounding tissue that predicts the risk of metastasis and poor survival. Our objective is to identify genes that are preferentially expressed in tumors and surrounding normal tissue of patients with IBC by comparing the IBC gene expression profile with the profile of non-IBC breast tumors. This is a novel approach. IBC is a rare disease, and it is difficult to collect flash-frozen IBC specimens that are suitable for array-based gene expression analysis. We have a particular interest in those genes that promote metastasis, and are expressed in the surrounding normal tissue, but not in cancer cells. To date, no report describes an expression profile in surrounding normal tissue that is associated with tumor metastasis and poor survival in breast cancer. However, a recently reported molecular signature of metastasis in primary breast tumors contained genes that are thought to be expressed in normal tissue, and not by cancer cells.
Specific aims 1) Array-based gene expression profiles will be generated for all breast tumors and the surrounding normal tissues, and for ten disease-free breast reduction tissues. We will use laser-captured microdissection to separate tumor from normal tissue. Supervised methods for class comparison and prediction will be used to establish gene expression profiles that distinguish 1) IBC tumors from surrounding normal tissue, 2) IBC tumors from non-IBC tumors, and 3) surrounding normal tissue of IBC tumors from surrounding normal tissue of non-IBC tumors. Non-IBC tumors will be subclassified into patient groups with either good or poor survival, and will be analyzed as separate groups. 2) Candidate marker genes for tumor progression and survival will be validated by Taqman, and further studied by immunohistochemistry, Western blotting, and in appropriate experimental models.
