Refining M1 stage in medulloblastoma: criteria for cerebrospinal fluid cytology and implications for improved risk stratification from the HIT-2000 trial

LOXL1-AS1 contributes to metastasis in sonic-hedgehog medulloblastoma by promoting cancer stem-like phenotypes

BACKGROUND

Medulloblastomas (MBs) are one of the most common malignant brain tumor types in children. MB prognosis, despite improvement in recent years, still depends on clinical and biological risk factors. Metastasis is the leading cause of MB-related deaths, which highlights an unmet need for risk stratification and targeted therapy to improve clinical outcomes. Among the four molecular subgroups, sonic-hedgehog (SHH)-MB harbors clinical and genetic heterogeneity with a subset of high-risk cases. Recently, long non-coding (lnc)RNAs were implied to contribute to cancer malignant progression, but their role in MB remains unclear. This study aimed to identify pro-malignant lncRNAs that have prognostic and therapeutic significance in SHH-MB.

METHODS

The Daoy SHH-MB cell line was engineered for ectopic expression of MYCN, a genetic signature of SHH-MB. MYCN-associated lncRNA genes were identified using RNA-sequencing data and were validated in SHH-MB cell lines, MB tissue samples, and patient cohort datasets. SHH-MB cells with genetic manipulation of the candidate lncRNA were evaluated for metastatic phenotypes in vitro, including cell migration, invasion, sphere formation, and expressions of stemness markers. An orthotopic xenograft mouse model was used to evaluate metastasis occurrence and survival. Finally, bioinformatic screening and in vitro assays were performed to explore downstream mechanisms.

RESULTS

Elevated lncRNA LOXL1-AS1 expression was identified in MYCN-expressing Daoy cells and MYCN-amplified SHH-MB tumors, and was significantly associated with lower survival in SHH-MB patients. Functionally, LOXL1-AS1 promoted SHH-MB cell migration and cancer stemness in vitro. In mice, MYCN-expressing Daoy cells exhibited a high metastatic rate and adverse effects on survival, both of which were suppressed under LOLX1-AS1 perturbation. Integrative bioinformatic analyses revealed associations of LOXL1-AS1 with processes of cancer stemness, cell differentiation, and the epithelial-mesenchymal transition. LOXL1-AS1 positively regulated the expression of transforming growth factor (TGF)-β2. Knockdown of TGF-β2 in SHH-MB cells significantly abrogated their LOXL1-AS1-mediated prometastatic functions.

CONCLUSIONS

This study proved the functional significance of LOXL1-AS1 in SHH-MB metastasis by its promotion of TGF-β2-mediated cancer stem-like phenotypes, providing both prognostic and therapeutic potentials for targeting SHH-MB metastasis.

CSF cytology of common primary CNS neoplasms categorized by CNS WHO 2021

OBJECTIVE

The detection of neoplastic cells in cerebral spinal fluid (CSF) is pivotal for the management of patients with central nervous system (CNS) tumours. This article delves into the CSF cytological characteristics of common CNS neoplasms, aligning with the 2021 World Health Organization (WHO) classification of CNS tumours.

METHODS

A retrospective review of CSF specimens positive for primary CNS neoplasms was performed at three tertiary medical centres. Only cases that had histopathologic confirmation and/or molecular workup were included.

RESULTS

Common primary CNS neoplasms seen in CSF cytology specimens include medulloblastoma, (non-WNT/non-SHH as well as SHH-activated and TP53 mutant), pineoblastoma, atypical teratoid/rhabdoid tumour (AT/RT), IDH-wildtype glioblastoma, and primary diffuse large B-cell lymphoma of the CNS. Ependymomas and germinomas can also have CSF involvement but are less common. Although the typical histologic architecture of these tumours may not be preserved in the CSF, unique cytomorphologic features such as nuclear moulding, nuclear pleomorphism, rhabdoid cells, prominent nucleoli and rosette formation can still be appreciated.

CONCLUSION

Adopting the updated terminology and correlating cytologic observations with molecular findings will streamline the diagnostic process, reducing the complexities and ambiguities pathologists often encounter when analysing CSF specimens for potential primary CNS neoplasms.

Clinical, Histological, and Molecular Prognostic Factors in Childhood Medulloblastoma: Where Do We Stand?

Medulloblastomas, highly aggressive neoplasms of the central nervous system (CNS) that present significant heterogeneity in clinical presentation, disease course, and treatment outcomes, are common in childhood. Moreover, patients who survive may be diagnosed with subsequent malignancies during their life or could develop treatment-related medical conditions. Genetic and transcriptomic studies have classified MBs into four subgroups: wingless type (WNT), Sonic Hedgehog (SHH), Group 3, and Group 4, with distinct histological and molecular profiles. However, recent molecular findings resulted in the WHO updating their guidelines and stratifying medulloblastomas into further molecular subgroups, changing the clinical stratification and treatment management. In this review, we discuss most of the histological, clinical, and molecular prognostic factors, as well the feasibility of their application, for better characterization, prognostication, and treatment of medulloblastomas.