Among the oligodendroglial lineage markers (Olig2, Sox10, ASCL1, and NKX2-2), ASCL1 and NKX2-2 displayed significantly different immunostaining between oligodendrogliomas and astrocytomas (p = 0.017 and 0.004, respectively), but none clearly differentiated between the 2 glial populations of oligoastrocytomas.
ASCL1 upregulation in progressive astrocytoma is accompanied by inhibition of Notch signaling as seen by uninduced levels of HES1, a transcriptional target of Notch1, increased levels of HES6, a dominant-negative inhibitor of HES1-mediated repression of ASCL1, and increased levels of Notch ligand Delta1, which is capable of inhibiting Notch signaling by forming intracellular Notch ligand autonomous complexes.