Five Novel Immunogenic Antigens in Meningioma: Cloning, Expression Analysis, and Chromosomal Mapping 1 Nicole Comtesse, 2 Dirk Heckel, 2 Alexander Ra ´cz, Nicole Brass, Brenda Glass, and Eckart Meese 3 Department of Human Genetics, Medical School, University of Saarland, D-66421 Homburg/Saar, Germany ABSTRACT Tumorigenesis of meningioma has been associated with chromosome 22, most notably the NF2 gene, but additional genes have been implicated in meningioma development. Here, we report the identification of five novel immunogenic antigens expressed in meningioma. An expression library was generated from a meningioma that retained both copies of chromosome 22. Screening with autologous patient serum identified seven cDNA clones that were indicated by antigen- antibody complexes. The clones were sequenced, and se- quence comparison revealed that the seven clones represent five different genes, providing evidence that meningiomas express a spectrum of immunoreactive antigens, which were termed meningioma expressed antigens (MGEAs). One gene was identical with the connective tissue growth factor, one gene was in part homologous to an Alzheimer disease-asso- ciated gene, and a third gene was in part identical to Homo sapiens molybdenum cofactor biosynthesis proteins A and C mRNA. One gene was partially homologous to previously reported cDNA sequences of unknown function, and the fifth gene showed no significant homologies to sequences deposited in databases. Using somatic hybrid mapping, three genes were localized on chromosome 6, and two genes were localized on chromosomes 3 and 17, respectively. To distinguish the MGEAs from the so-called natural autoan- tigenes, we also screened the library with 12 sera from individuals without obvious disease. The clones identified by reactivity with normal sera were completely different from the clones identified by screening the same meningioma expression library with serum from the patient bearing the tumor. These data suggest that the newly identified MGEA genes may be useful for diagnosis and possibly therapy of meningioma. INTRODUCTION Meningioma, which represent 20% of all adult intracra- nial tumors, are neoplasms of the meninges covering the brain and the spinal cord (1). First evidence for causative genetic changes in meningioma has been derived from cytogenetic studies demonstrating the loss of one copy of chromosome 22 in the majority of the cases (2). Heterozygous loss of the long arm of chromosome 22 has been found in 70% of meningioma (3), strongly indicating tumor suppressor gene(s) on chromosome 22. Although there is clear evidence for an involvement of the NF2 gene, which maps at 22q12.2, 40% of the meningiomas do not show mutations within the NF2 gene, indicating that there are additional genes involved in the tumorigenesis of meningi- oma (4). Because meningiomas are generally sporadic, the ad- ditional hypothesized suppressor gene(s) could not be mapped by linkage analysis. Deletion studies did not reveal a specific region harboring meningioma suppressor gene(s) on chromo- some 22. To further understand the molecular pathology of meningioma, several studies took a different approach by fo- cusing on the role of growth factors in this tumor. Specifically, the platelet-derived growth factor , the insulin-like growth factors I and II, and the fibroblast growth factors have been postulated to contribute to the uncontrolled growth of meningi- omas in an autocrine fashion (5–7). In 1976, Pees and Seidel (8) described a cellular immune response against autologous and heterologous meningioma cells in the serum of the patients. Another study concerning cytotoxic immune responses presents data that suggests that meningiomas can induce complex immunological responses in the host (9). The presence of IgG in meningiomas was shown by Tabuchi et al. (10) in 1981. Expression of MHC I and MHC II molecules in meningioma tissues was detected also (11, 12). All of these data indicate that meningiomas are capable of inducing immune responses in the host. Recent studies provide evidence that many tumors express antigens that elicit an immune response in the patient bearing the tumor. The expression of tumor-associated antigens is likely to reflect underlying intracellular changes, including the over- expression of genes or mutations within the DNA sequence. For the majority of human tumors, however, only a limited number of antigens have been identified. Tumor-associated antigens have been described, mostly for malignant cancers including melanoma, breast cancer, and ovarian cancer (13–16). Most recently, we reported cloning of two immunoreactive antigens expressed in meningioma, providing the first evidence for the expression of immunogenic antigens in this tumor type (17, 18). Here, we report five additional immunoreactive antigens ex- pressed in meningioma demonstrating that benign tumors, such as meningioma, may be characterized by several immunogenic antigens. The antigen-encoding genes were sequenced and lo- calized by somatic hybrid mapping or fluorescence in situ hybridization. For control, we screened the same meningioma Received 4/16/99; revised 8/6/99; accepted 8/16/99. The costs of publication of this article were defrayed in part by the payment of page charges. This article must therefore be hereby marked advertisement in accordance with 18 U.S.C. Section 1734 solely to indicate this fact. 1 This work was supported by Grant SFB 399, A4 from the Deutsche Forschungsgemeinschaft. 2 These authors contributed equally to this work. 3 To whom requests for reprints should be addressed, at Department of Human Genetics, University of Saarland, Building 60, 66421 Homburg/ Saar Germany. Phone: 49-6841-166038; Fax: 49-6841-166186; E-mail: hgemee@med-rz.uni-sb.de. 3560 Vol. 5, 3560 –3568, November 1999 Clinical Cancer Research Research. on November 26, 2021. © 1999 American Association for Cancer clincancerres.aacrjournals.org Downloaded from