Investigating the oncogenic potential of snoRNA HBII-52 and the serotonin 5HT2C receptor in pediatric medulloblastoma
Suddaby, Jessica Sachiko
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Medulloblastoma is the most common malignant pediatric brain tumor and is known for its aggressive and invasive phenotype. Current treatment methods for medulloblastoma consist of surgery, chemotherapy, and radiation. However, there is considerable treatment toxicity associated with these treatment methods. One alternative treatment method that is currently being examined is molecular drug targeting therapy using small nucleolar RNAs (snoRNAs) as non-invasive cancer biomarkers. HBII-52, a brain-specific C/D box snoRNA that is responsible for the RNA editing of the serotonin 2C receptor (5-HT 2C R). HBII-52 is of interest with respect to brain cancer because the 5-HT 2C R has been implicated in oncogenesis. The 5-HT 2C R activates pro-proliferative and prosurvival pathways, thereby increasing cellular invasion and migration. It is hypothesized that pharmacologic treatment of Daoy medulloblastoma cells with SB 242,084, a 5-HT 2C R-specific inhibitor will block 5-HT 2C R downstream pathways, thereby inhibiting cell invasion and migration. In this study, two tetraycycline-inducible derivatives of the Daoy medulloblastoma cell line, HBII-52 Tet and shLacZ Tet (control), were examined at the biological level using FACS analysis, P1000 scratch wound healing assays, and Transwell cell invasion and migration assays. Daoy cells were also examined at the molecular level using Western blotting. Overall, while HBII-52 overepxression did not affect cell cycle progression or non-chemotactic migration, treatment of HBII-52 Tet cells with SB 242,084 did significantly decrease chemotactic migration and invasion. Western blotting results indicated that RhoA expression was not consistently affected by HBII-52 overexpression or SB 242,084 treatment as anticipated. pERK expression, however, decreased with SB 242,084 treatment. Therefore, it is believed that pERK may be regulated through a different 5-HT 2C R downstream pathway, namely the PLCβ pathway.