An HSP90-mimic peptide revealed by fingerprinting the pool of antibodies from ovarian cancer patients

Abstract

To gain insight into the mechanisms of molecular recognition and humoral immune response in ovarian cancer, we used fingerprinting, a phage display-based combinatorial selection to isolate peptide ligands to tumor-related antibodies present in ascites from patients with advanced disease. First, we have isolated a consensus motif (sequence CVPELGHEC) in 86% of the peptides screened; this enriched motif was selected from a total of 10(8)-10(9) unique random sequences present in the library. Next, we identified the heat-shock protein 90 kDa (HSP90) as the native antigen mimicked by the motif. Finally, we evaluated the expression of HSP90 and the presence of antibodies against the HSP90-mimic peptide in a large panel of ovarian cancer patients and controls. In tissue microarrays, we show that the expression of HSP90 is ubiquitous. However, the corresponding humoral immune response against HSP90 is restricted to a subset of patients with stage IV disease. Together, these results show that screening humoral response can identify tumor antigens that may serve as molecular targets in ovarian cancer. Recognition of such relevant proteins in the immunobiology of malignant tumors may lead to the development of therapies

Discovery and horizontal follow-up of an autoantibody signature in human prostate cancer

“…Fingerprinting of enriched serum antibodies with phage display offers a more direct combinatorial screening for antibody epitopes and has identified numerous biologically relevant antigens (7)(8)(9)(10)(11)(12). Moreover, studies from other laboratories have indicated clinical relevance in cancer diagnostics for antibodies against molecules such as osteopontin (20,21), isoprostanes (22), and CXCL13 (23), among others.…”

“…antigenicity of a tumor and may identify serum autoantibodies of diagnostic and prognostic value. We applied a phage display fingerprinting approach (7,8) on isolated antibodies from sequentially acquired serum samples from an index patient and performed three rounds of selection for each time point. Relative phage recovery was very similar from serum obtained at initial diagnosis of castrate-sensitive prostate adenocarcinoma (year 0) and serum obtained during androgen ablation treatment, in which PSA was undetectable (year 1) (Fig.…”

“…Specific autoantibodies and their cognate tumor-associated antigens have been characterized, e.g., GRP78 for prostate cancer (9), HSP90 for ovarian cancer (8), ubiquilin 1 in lung cancer (10), and annexin XI-A in breast cancer (11). In addition, phage-based screening approaches have been developed for high-throughput profiling of immunogenic antigens for prostate cancer (12).…”

“…Using combinatorial peptide phage libraries, we developed a fingerprinting method based on targeting of circulating tumorassociated antibodies isolated from cancer patients (7,8). Specific autoantibodies and their cognate tumor-associated antigens have been characterized, e.g., GRP78 for prostate cancer (9), HSP90 for ovarian cancer (8), ubiquilin 1 in lung cancer (10), and annexin XI-A in breast cancer (11).…”

An antivascular vaccine to boost self-immunity and strike the tumor

“…Such a high-throughput approach proved effective in the identification of autoantibody signatures in prostate and ovarian cancer (6)(7)(8). In ongoing work, we have applied this protocol to sera from an index patient with welldocumented spontaneously regressed metastatic RCC (9), as well as to a classic experimental rat model of RCC (10), corroborating the presence of a humoral immunity against the broad repertoire of tumor vascular antigens.…”