Erythropoietin receptor expression in normal and neoplastic choroid plexus

Background: The erythropoietin receptor (EpoR) is expressed widely throughout the human CNS, including the choroid plexus. Recent studies have shown that EpoR is also expressed in various human tumors, including carcinomas, meningiomas and gliomas. Thereby, the Epo-EpoR pathway plays a role in inhibition of apoptosis and tumor growth, infiltration, angiogenesis and metastasis as well as treatment resistance and is a potential target in oncological treatment. Lower levels of EpoR have been associated with shorter survival in high grade gliomas and higher risk of tumor re-currence in meningiomas. Methods: Since the EpoR status in human choroid plexus tumors (CPT) is not known, we investigated 57 CPT from 43 cases including 14 recurrent tumors and compared them with 23 samples of normal choroid plexus (CP). CPT samples consisted of choroid plexus papillomas/CPP (n = 41), atypical CPP (n = 15) and choroid plexus carcinoma/CPC (n = 1). EpoR expression was determined by immunohistochemistry using semi-quantitative scoring for staining intensity and was validated in exemplary cases using western blot and RT-PCR. Results: EpoR expression was observed in all samples of normal and neoplastic CP with significantly lower expression levels in CPT (p<0.001). Conclusion: No significant correlation was found between EpoR expression and age, gender, WHO grade, number of mitosis or tumor recurrence. EpoR expression in CPT is in line with its expression in normal CP and with previous reports on EpoR expression in other glial neoplasms. Association of EpoR levels in CPT with survival, as known in astrocytic gliomas, remains to be determined.