Abstract B7: Comparison of HOX transcriptional factors and tumor characteristics in medulloblastoma cell lines and adult medulloblastoma
Authors: Fontes Aparecida Maria , Silva Ricardo Bonfim , Veiga Julia Borges , Tirapelli Daniela Pretti da Cunha , Ramalho Fernando Silva , Covas Dimas Tadeu , Machado Hélio Rubens , Riggins Gregory J. , Carlotti Carlos Gilberto 
Published: May 2015

Introduction: Medulloblastoma is an embryonal neuroepithelial tumor of the cerebellum and accounts for 15-30% of all pediatric cancer of central nervous system (CNS) and for 1-3% of all adult brain tumors. Medulloblastoma is a heterogeneous cancer and classified in four main subgroups: WNT, SHH, Group 3 and Group 4. The elucidation of the biological meaning of these subgroups requires understanding the interactions among several molecular pathways that are deregulated during oncogenesis resulting in clinicalpathological differences. The goal of this study is to elucidate the HOX pattern expression in four medulloblastoma cell lines and compare with their morphological in vitro features and in vivo tumorigenic potential as well as to identify HOX pattern expression in adult medulloblastoma.

Methodology: We investigated four medulloblastoma cell lines: DAOY, ONS-76, UW473 and UW402, three primary cerebellum cultures and four adult medulloblastoma samples. We compared the immunophenotype, proliferative potential, matrigel invasion and cell migration under in vitro conditions of these four cell lines. Also, we examined their potential to induce tumor in athymic nude mice. Quantitative real-time RT-PCR assay were established for five HOX genes: HOXA3, A10, B3, B4 and B6 on these four cell lines, on three additional cerebellum primary cultures and four adult medulloblastoma samples.

Results: We found that, these medulloblastoma cell lines exhibit differences for six of the eleven mesenchymal markers evaluated (CD144, CD140b, CD24, CD146, CD90 and CD271). The potential proliferative assay showed that the population doubling of ONS-76 is 1.1-1.4 fold lower compared with the other cell lines. Migration in a wound healing assay showed that DAOY present greater migration capacity compared to the others cell lines (p &lt; 0,0001). The UW402 exhibited 1.5-1.9 fold higher invasion through Matrigel than UW473 and ONS-76. DAOY cell line did not exhibit invasive property in Matrigel. In DAOY and ONS-76 cell lines, HOXA3, A10, B3, B4 and B6 showed higher expression compared to UW473 and UW402 cell lines. Of note, in DAOY and ONS-76 HOXA10 is expressed 19,398 ± 931 and 9,903 ± 713 fold higher compared with cerebellum control. In adult medulloblastoma HOXA10, B3, B4 and B6 were evaluated. Of note, HOXA10 is expressed 6,579 fold higher in one sample compared with normal cerebellum, while in the other samples the variation in HOX expression was not the same. Interesting, we observed that 100% of the recipient mice that received DAOY and ONS-76 cell lines developed tumors, while no tumors were developed in UW7473 and UW402 groups.

Conclusion: This study demonstrates that these four cell lines exhibit differences in immunophenotype, invasion and migration properties and proliferative potential. Moreover, five HOX genes were examined, of which, two exhibited changes in transcript level that could be correlated with in malignant phenotype. In adult medulloblastoma, variations of these HOX genes were observed, which might reflect differences in medulloblastoma subypes. Further understanding about the role of HOX transcriptional factors for establishing the malignant phenotype requires molecular characterization of these four medulloblastoma cell lines and adult medulloblastoma.

Citation Format: Aparecida Maria Fontes, Ricardo Bonfim Silva, Julia Borges Veiga, Daniela Pretti da Cunha Tirapelli, Fernando Silva Ramalho, Dimas Tadeu Covas, Hélio Rubens Machado, Gregory J. Riggins, Carlos Gilberto Carlotti Jr. Comparison of HOX transcriptional factors and tumor characteristics in medulloblastoma cell lines and adult medulloblastoma. [abstract]. In: Proceedings of the AACR Special Conference on Pediatric Cancer at the Crossroads: Translating Discovery into Improved Outcomes; Nov 3-6, 2013; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2013;74(20 Suppl):Abstract nr B7.