Abstract 1285: The pro-metastatic role of long-noncoding RNA LOXL1-AS1 in sonic-hedgehog medulloblastoma
Authors: Do Anh Duy , Hsieh Chia-Ling , Wong Tai-Tong , Sung Shian-Ying 
Published: April 2023

Introduction: Medulloblastoma (MB) is the most common malignant tumor in children. Since most MB-related deaths are the result of metastasis, current standard care for MB is aggressive with intense post-surgical radiotherapies, which aim to minimize metastatic occurences and are applied in most cases regardless of tumor subgroups. Among the four molecular subgroups, sonic-hedgehog (SHH-) MB has a high prevalence and well-characterized profiles. A proportion of SHH-MB cases with higher metastasis rate and worse prognosis have been linked to aberrant expressions of certain genes such as MYCN. Strategies to target such pro-metastatic drivers have been explored but proven to be challenging. Therefore, discovery of novel targets in MB is an urgent need to optimize treatment and improve outcomes. Long non-coding RNAs (lncRNAs) have recently emerged as malignancy regulators in many cancers. More insights into the role of lncRNAs in metastasis-promoting phenotypes, especially cancer stemness, would present both prognostic and therapeutic significance in metastatic MB.

Objective: To determine the role of lncRNA LOXL1-AS1 in progression and metastasis of SHH-MB.

Methods: First, we used RNA-sequencing to screen for differentially expressed lncRNAs in SHH-MB cells (Daoy) achieved a higher malignancy level via MYCN overexpression (Daoy-MYCN), identifying LOXL1-AS1 as one of the pro-malignant lncRNA candidates. LOXL1-AS1 expressions and prognostic associations were validated in clinical samples and datasets. Next, MB cells with stable LOXL1-AS1 knockdown (Daoy-MYCN) or overexpression (Daoy and ONS-76) were subjected to migration and invasion assays, as well as seeded in sphere-forming condition to assess sphere formation capacities and stemness marker expressions. Finally, we injected Daoy-MYCN cells knockdown of LOXL1-AS1 into BALB/c mouse brain to observe formation of tumor, metastasis, and survival rates.

Results: LOXL1-AS1 was increased in Daoy cells under MYCN overexpression, was highly expressed in MB compared to normal brain, and was associated with poor prognosis in SHH-MB, particularly in the SHH-α and SHH-γ subgroups. MB cells with LOXL1-AS1 knockdown or overexpression showed a significant decrease or increase, respectively, in cell migration, cell invasion, sphere numbers, sphere diameters, and expression of stemness markers. Mice orthotopically transplanted with LOXL1-AS1-knockdown cells experienced a delayed tumor growth and metastasis development with improved overall and metastasis-free survivals.

Conclusion: Our study has proven the role of LOXL1-AS1 in pro-metastatic phenotypes of MYCN-associated SHH-MB through a possible mechanism of inducing cancer stemness, which expands our current array of lncRNA candidates to develop MB-targeted therapies. The mechanisms of LOXL1-AS1-driven metastasis are being investigated in MB models.

Citation Format: Anh Duy Do, Chia-Ling Hsieh, Tai-Tong Wong, Shian-Ying Sung. The pro-metastatic role of long-noncoding RNA LOXL1-AS1 in sonic-hedgehog medulloblastoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 1285.