Abstract 5571: Identification of autoantibody biomarkers in metastatic osteosarcoma using a high-density protein microarray approach

Abstract

Abstract Osteosarcoma (OS) is the most common malignant bone tumor in children and adolescents. A leading cause of death in OS is the development of metastasis. Therefore, it is important to detect metastatic patients as early as possible, so these patients can be stratified and treated while the disease is still in its early stages and potentially curable. Autoantibodies represent a promising class of plasma proteins that can be used for the early detection of cancer. These immunoglobulins can recognize aberrant proteins in the tumor cell during the development of metastasis. We have used a new high-density protein microarray platform, ProtoArray Human Protein Array (HPA), to identify significant autoantibody biomarkers that are associated with metastatic OS at the time of diagnosis. ProtoArray HPA consists of over 8,000 purified human proteins from different functional classes. Plasma samples from metastatic and localized OS patients, and children with non-cancerous diseases were analyzed by the microarrays. The results showed that the amounts of 136 distinct autoantibodies were significantly different between the plasma samples of metastatic and localized OS cases (p < 0.01). Among these autoantibodies, 66 were higher while 70 were lower in metastatic patients. Two of these autoantibodies, which target CTTN and PFKFB1, were selected for further investigation. We found that the phosphorylated form (p85) of the CTTN protein in two metastatic OS cell lines was expressed higher relative to the non-metastatic parental cells. This result is consistent with the previous finding that increased phosphorylation of CTTN is important for the metastatic phenotype of cancer cells. The PFKFB1 autoantibody in the localized patients was higher than the metastatic patients; however, both groups of OS patients had a higher PFKFB1 level relative to the control group. When compared to normal osteoblasts, Western blotting showed that PFKFB1 protein was overexpressed in seven of the eight OS cell lines. PFKFB1 is involved in the Warburg effect, which is important to the energy metabolism of cancer cells. Our results suggest that the high-density protein microarray approach is useful for identifying metastasis-associated autoantibodies in cancer patients. Further validation and investigation of the candidate autoantibody biomarkers may lead to discovery of novel biomarkers and unravel the underlying mechanism in metastatic OS. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 5571.