From the Cover: Neutralization of terminal differentiation in gliomagenesis
Jian Hu1, Allen L Ho, Liang Yuan
1Department of Cancer Biology, University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA.
Abstract:
An immature state of cellular differentiation--characterized by stem cell-like tendencies and impaired differentiation--is a hallmark of cancer. Using glioblastoma multiforme (GBM) as a model system, we sought to determine whether molecular determinants that drive cells toward terminal differentiation are also genetically targeted in carcinogenesis and whether neutralizing such genes also plays an active role to reinforce the impaired differentiation state and promote malignancy. To that end, we screened 71 genes with known roles in promoting nervous system development that also sustain copy number loss in GBM through antineoplastic assay and identified A2BP1 (ataxin 2 binding protein 1, Rbfox1), an RNA-binding and splicing regulator that is deleted in 10% of GBM cases. Integrated in silico analysis of GBM profiles to elucidate the A2BP1 pathway and its role in glioma identified myelin transcription factor 1-like (Myt1L) as a direct transcriptional regulator of A2BP1. Reintroduction of A2BP1 or Myt1L in GBM cell lines and glioma stem cells profoundly inhibited tumorigenesis in multiple assays, and conversely, shRNA-mediated knockdown of A2BP1 or Myt1L in premalignant neural stem cells compromised neuronal lineage differentiation and promoted orthotopic tumor formation. On the mechanistic level, with the top-represented downstream target TPM1 as an illustrative example, we demonstrated that, among its multiple functions, A2BP1 serves to regulate TPM1's alternative splicing to promote cytoskeletal organization and terminal differentiation and suppress malignancy. Thus, in addition to the activation of self-renewal pathways, the neutralization of genetic programs that drive cells toward terminal differentiation may also promote immature and highly plastic developmental states that contribute to the aggressive malignant properties of GBM.
Insights
Cancer cells often remain immature. Researchers found that restoring A2BP1 or Myt1L genes in glioblastoma cells inhibited tumor growth and promoted differentiation, highlighting their role in cancer development.
Area of Science:
- Neuro-oncology
- Cancer Biology
- Developmental Neuroscience
Background:
- Cancer, particularly glioblastoma multiforme (GBM), is characterized by immature, poorly differentiated cells.
- Understanding the genetic mechanisms that maintain this undifferentiated state is crucial for developing new therapies.
Purpose of the Study:
- To investigate if genes promoting neuronal differentiation are targeted during glioblastoma development.
- To determine if inhibiting these differentiation pathways contributes to cancer malignancy.
Main Methods:
- Screened 71 nervous system development genes for copy number loss in GBM.
- Utilized antineoplastic assays and in silico analysis to identify and study A2BP1 and its regulator Myt1L.
- Employed cell line and animal models, including gene reintroduction and knockdown experiments.
Main Results:
- Identified A2BP1 (ataxin 2 binding protein 1), an RNA-binding protein, as deleted in 10% of GBM cases.
- Found Myt1L to be a direct transcriptional regulator of A2BP1.
- Restoring A2BP1 or Myt1L inhibited GBM tumorigenesis and promoted differentiation; their knockdown impaired differentiation and increased tumor formation.
Conclusions:
- A2BP1 regulates alternative splicing of TPM1, promoting cytoskeletal organization and terminal differentiation.
- Inhibition of differentiation pathways, alongside self-renewal activation, contributes to GBM's aggressive nature.
- Targeting genetic programs that suppress differentiation offers a potential therapeutic strategy for glioblastoma.
