CRX is a diagnostic marker of retinal and pineal lineage tumors.
BACKGROUND
CRX is a homeobox transcription factor whose expression and function is critical to maintain retinal and pineal lineage cells and their progenitors. To determine the biologic and diagnostic potential of CRX in human tumors of the retina and pineal, we examined its expression in multiple settings.


RESULTS
Using situ hybridization and immunohistochemistry we show that Crx RNA and protein expression are exquisitely lineage restricted to retinal and pineal cells during normal mouse and human development. Gene expression profiling analysis of a wide range of human cancers and cancer cell lines also supports that CRX RNA is highly lineage restricted in cancer. Immunohistochemical analysis of 22 retinoblastomas and 13 pineal parenchymal tumors demonstrated strong expression of CRX in over 95% of these tumors. Importantly, CRX was not detected in the majority of tumors considered in the differential diagnosis of pineal region tumors (n = 78). The notable exception was medulloblastoma, 40% of which exhibited CRX expression in a heterogeneous pattern readily distinguished from that seen in retino-pineal tumors.


CONCLUSIONS
These findings describe new potential roles for CRX in human cancers and highlight the general utility of lineage restricted transcription factors in cancer biology. They also identify CRX as a sensitive and specific clinical marker and a potential lineage dependent therapeutic target in retinoblastoma and pineoblastoma.
Santagata
Sandro
S
Department of Pathology, Brigham and Women's Hospital, Boston, Massachusetts, United States of America.
Maire
Cecile L
CL
Idbaih
Ahmed
A
Geffers
Lars
L
Correll
Mick
M
Holton
Kristina
K
Quackenbush
John
J
Ligon
Keith L
KL
D000818:Animals; D019070:Cell Lineage; D020869:Gene Expression Profiling; D018507:Gene Expression Regulation, Developmental; D015972:Gene Expression Regulation, Neoplastic; D018398:Homeodomain Proteins / Q000235:genetics* / Q000502:physiology; D006801:Humans; D051379:Mice; D008810:Mice, Inbred C57BL; D008957:Models, Genetic; D009369:Neoplasms / Q000378:metabolism*; D010870:Pineal Gland / Q000473:pathology*; D012160:Retina / Q000473:pathology*; D019572:Retinal Neoplasms / Q000378:metabolism*; D015534:Trans-Activators / Q000235:genetics* / Q000502:physiology
D018398:Homeodomain Proteins; D015534:Trans-Activators; C109288:cone rod homeobox protein