Abstract 3589: Comparative expression profile of transmembrane mucin MUC1 in breast cancer from American Indian and Caucasian women

Abstract

Abstract Introduction: Considerable disparity exists in breast cancer incidence and mortality among different racial/ethnic populations and geographic locations. For unknown reasons, American Indian women of the Northern Plains have a greater incidence and higher death rate due to breast cancer than Caucasian women living in the same geographical region. Additionally, American Indian women living in the Northern Plains also have a much higher incidence and death rate due to breast cancer than American Indian women living elsewhere in the United States. To investigate the potential molecular basis for this cancer health disparity, we have compared the expression profile of transmembrane mucin, MUC1 on breast cancer cases from American Indian and Caucasian women living on the Northern Plains. MUC1 is known to be overexpressed in breast cancer and nuclear localization of MUC1 can have downstream effects on cell signaling and increase oncogenic phenotypes. We are also exploring the link between smoking, exposure to HPV infection, and the development of breast cancer in American Indian women. Methods: We have examined the expression profile of MUC1 in breast cancer tissue from American Indian (n=40) and Caucasian (n=60) women. The staining was analyzed by experienced pathologists and scored according to intensity (0-4) and percent of cancer cells stained positive (0-4). A composite score was calculated by multiplying the scores of intensity and percent of cells stained. Tissues were categorized by modified Bloom-Richardson's histological grade and the mean composite scores were compared amongst American Indian and Caucasian groups. Results and Conclusions: We have observed that grade 3 breast cancer samples from American Indian women had a higher percent of nuclear MUC1 staining and a lower amount of p53 expression. This result correlates with previous data showing that MUC1 inhibits the expression of p53. In conclusion, breast cancer tissue from American Indian women has a different expression profile of molecular markers and this finding may help to explain the cancer health disparity. Further investigation of these differences may promote understanding of the etiological differences and may identify effective treatment strategies for breast cancer in American Indian women. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 3589. doi:1538-7445.AM2012-3589