Abstract. Breast cancer is a major health burden, responsible for >10% of all cases of cancer worldwide. Advances in breast cancer diagnosis and treatment have contributed to an improved rate of survival, although mortality rates remains significantly high. The establishment of breast cancer cell lines is an important model for understanding biological processes involved in this disease and for identifying potential therapeutic targets. The novel human breast cancer cell lines, MACL-1 and MGSO-3, were used in this study to identify possible surface antigens by antibodies directed against two commercial breast cancer cell lines MCF-7 and MDA-MB-231. We purified a 37 kDa antigen by affinity chromatography from MDA-MB-231, and its N-terminal amino acid sequence was homologous to glyceraldehyde-3-phosphate dehydrogenase (GAPDH). Therefore, immunohistochemical experiments, using specific monoclonal antibodies, evidenced a co-localization of GAPDH and Na + /K + -ATPase on the surface of commercially available and recently established breast cancer cell lines. It is of note that Na + /K + -ATPase was used as a plasma membrane marker. This finding opens new perspectives for breast cancer diagnosis and treatment since GAPDH could be used as a biomarker or as a potential therapeutic target in breast cancer.
IntroductionCancer is a public health problem worldwide. Among the various types of cancer, breast cancer is the most common in women, in both high and low-resource settings, and is responsible for over one million of the estimated 10 million neoplasms diagnosed in both sexes worldwide each year (1). It is also the primary cause of death among women globally, responsible for ~375,000 deaths in the year 2000 (1). Although the 5-year survival rate has greatly increased as a result of advances in detection and treatment, many breast cancer patients still die from metastatic disease. Therefore, more effective methods of prevention and treatment are greatly needed.Cell cultures, established directly from patients, are an important model for examining and manipulating the potentially relevant molecules and cellular processes underlying malignant breast disease. However, selective culture of neoplastic cells and successful establishment of new cell lines have rarely been reported from primary breast carcinomas (2,3).The discovery of T-cell recognition and subsequent lysis of human tumors led to the identification of specific oncoproteins or mutated oncogenes (e.g., MUC-1, HER-2, CEA, and p53) (4-7). Many of these tumor antigens are found on normal tissues, but in cases of oncogenesis, are recognized by the immune system due to their overexpression. Some proteins are tumor-specific, but others, such as the universal tumor Ag hTERT, are broadly expressed by most tumor cells (8,9).In the present study, we describe a potential therapeutic target antigen on breast cancer cell lines, established from primary breast carcinoma by Correa et al (9). Using antibodies directed against the commercial cell lines MCF-7 and MDA-MB-231, we we...