Several types of
tumors are known to originate from the pineal region, among them
pineal parenchymal tumors (PPTs) and papillary
tumors of the pineal region (PTPRs), probably derived from the subcommissural organ. As a result of their rarity, their histologic diagnosis remains difficult. To identify molecular markers, using CodeLink
oligonucleotide arrays, gene expression was studied in 3 PPTs (2
pineocytomas and one
pineoblastoma), 2 PTPRs, and one chordoid
glioma, another rare
tumor of the third ventricle. Because PTPR and chordoid
glioma may present ependymal differentiation, gene expression was also analyzed in 4
ependymomas. The gene patterns of the 3 PPTs fell in the same cluster. The
pineocytomas showed high expression of TPH,
HIOMT, and genes related to phototransduction in the retina (OPN4, RGS16, and CRB3), whereas the
pineoblastoma showed high expression of UBEC2, SOX4, TERT, TEP1, PRAME, CD24, POU4F2, and HOXD13. Using
reverse transcriptase-polymerase chain reaction on 13 PPTs, we demonstrated that PRAME, CD24, POU4F2, and HOXD13 might be candidates for grading PPT with intermediate differentiation. PTPRs, classified with chordoid
glioma and separately from
ependymomas, showed high expression of SPEDF, KRT18, and genes encoding
proteins reported to be expressed in the subcommissural organ, namely ZFH4, RFX3, TTR, and CGRP. Our results highlight the usefulness of gene expression profiling for classify
tumors of the pineal region and identify genes with potential use as diagnostic markers.