SEREX Screening for Breast Cancer Tumor Antigens Using a Testis Lambda Zap Library
Breast Cancer is the second leading cause of cancer-related mortality in women. Better screening tests for early-stage disease as well as new treatment strategies for late-stage disease are needed. Within the past decade new discoveries have established that early-stage breast tumors evoke humoral and cellular immune responses to over-expressed or mis-expressed gene products. Although the immune system recognizes these tumor proteins, these responses ultimately fail to eliminate the tumors. The identification of a panel of tumor antigens that are immunogenic in early-stage breast cancer may serve in potential non-invasive screening tests for early-stage disease. In addition, these antigens may also serve as immunotherapeutic targets for patients with late-stage breast cancer. Through the use of immunoscreening technique known as SEREX, antigens that elicit antibody responses in cancer patients can be efficiently identified and cloned. This technique relies on the construction of cDNA libraries from tumor cDNA. These cDNAs are cloned into lambda bacteriophage expression vector. Libraries are screened by transfecting E. coli with the viral phage library. The proteins produced by each phage are bound to nitrocellulose membranes, which are then exposed to cancer patient serum. Those phages that bind patient antibodies are considered candidate tumor antigens and are isolated and identified by DNA sequencing. Inc discovering a diverse repertoire of novel antigens, the sensitivity of screening applications would increase and the development of a polyvalent tumor vaccine would become more feasible.
