Cancer‐germline gene expression in pediatric solid tumors using quantitative real‐time PCR

Abstract

Cancer-germline genes (CGGs) code for immunogenic antigens that are present on various human tumors but not on normal tissues. The importance of CGGs in cancer immunotherapy has led to detailed studies of their expression in a range of human tumors. We measured the levels of expression of 12 CGGs in various pediatric solid tumors to identify targets for therapeutic cancer vaccines. Quantitative real-time PCR (qPCR) was used to measure the expression of 8 MAGE genes and of genes LAGE-2/NY-ESO-1 and GAGE-1, 2, 8 in 9 osteosarcomas, 10 neuroblastomas, 12 rhabdomyosarcomas and 18 Ewing's sarcomas. Nine tumors were also examined by immunohistochemistry with monoclonal antibodies specific for the MAGE-A1, MAGE-A4 and NY-ESO-1 proteins. All osteosarcoma and 80% of neuroblastoma samples expressed several CGGs at high levels. Six of 12 rhabdomyosarcomas and 11 of 18 Ewing's sarcomas expressed at least one CGG. Immunohistochemistry data correlated well with qPCR results and showed a homogeneous protein distribution pattern in most positive tumors. No correlation was found between the levels of CGG expression in the tumors and clinicopathological parameters of the patients. Pediatric solid tumors express several CGGs, which encode antigens that could be targeted in therapeutic vaccination trials. Several CGGs of the MAGE, GAGE and LAGE families are coexpressed in a large proportion of osteosarcoma and neuroblastoma samples. Some rhabdomyosarcomas express several of these genes at high levels. Ewing's sarcomas have an overall low CGG expression. ' 2006 Wiley-Liss, Inc.Key words: cancer; pediatrics; qPCR; MAGE; NY-ESO-1 Human tumors bear antigens that can be specifically recognized by autologous T lymphocytes and antibodies.1-3 It has been shown in animal models and in clinical trials that vaccination with these tumor-specific antigens can lead to the eradication of tumors. 4,5 Over the last decade, promising new treatment modalities of induction of tumor-specific T cells have been proposed and applied. 6,7 Cancer-germline genes (CGGs) are expressed in male germline cells, not in other normal adult tissues, and in many tumors. Because male germline cells do not express HLA molecules on their surface, they do not express antigens that can be recognized by T cells. As a result, the antigens encoded by CGGs are strictly tumor-specific T cell or antibody targets. These antigens are shared by many tumors. CGGs include the MAGE, [8][9][10]12 and LAGE/NY-ESO-1 13,14 families. The MAGE gene family comprises 24 genes ranged in 3 subfamilies, MAGE-A, -B and -C. A large number of antigenic peptides encoded by the MAGE, GAGE and LAGE/NY-ESO-1 genes have been found to be presented to CD4 and CD8 lymphocytes by HLA molecules expressed at the surface of tumor cells. 15Several clinical trials in which antigens encoded by CGGs were used as vaccines have shown induction of immunological responses and, in a small number of patients, clinical responses. [16][17][18][19][20][21][22] Immunotherapy is an attractive therapeutic modality for pediat...

Pathway simulations in common oncogenic drivers of leukemic and rhabdomyosarcoma cells: A systems biology approach

“…A number of studies have investigated the detection of cancer germ line genes (CGGs) both in pediatric sarcomas (3) and pediatric brain tumors (4). The discovery of global antigens for tumor vaccines could become salvatory for childhood malignancies (3).…”

“…The discovery of global antigens for tumor vaccines could become salvatory for childhood malignancies (3). Other studies have reported the common appearance of antigens in Ewing's sarcoma/primitive neuroectodermal tumor (EWS/PNET) with lymphoblastic lymphoma (5).…”

Development of Checkpoint Inhibitors for Sarcomas

“…46,47 Among the large family of TAAs, expression of cancer testis antigens (NY-ESO, MAGE-A3, MAGE-A4, PRAME, and LAGE) occurs in a variety of sarcomas, including synovial sarcomas, myxoid round-cell liposarcoma, osteosarcoma, ES, chondrosarcoma, leiomyosarcoma, and UPS. [48][49][50] Nevertheless, and as expected for such a heterogeneous group of tumors, immunogenicity is not uniform among sarcomas, and can be influenced by the tumor genomic landscape or mutational load. Across different histologies, and particularly in melanoma and non-small cell-lung cancer, increased number of somatic missense mutations and mutational epitopes have been associated with patient survival and benefit from both anti-CTLA-4 and anti-PD-1 agents, 57 High levels of somatic copy number alterations (aneuploidy) have been shown to correlate with total number of mutations, elevated markers of cell cycle/proliferation, reduced expression of markers for cytotoxic immune cell infiltrates, and poorer prognosis in melanoma patients treated with anti-CTLA therapy, supporting the concept that aneuploidy is involved in mechanisms of cell proliferation and immune evasion.…”

Targeted immunotherapy for pediatric solid tumors

“…CTAs comprise 70 families with over 140 antigens. 12,73 Their biologic function is not fully understood, but because of their immunogenicity they are being studied as T cell targets for vaccine and adoptive cellular therapy. However, not all antigens are immunogenic in all patients and expression of the antigens may vary between patients.…”