Progesterone receptor isoforms expression pattern in human chordomas

Steroid hormone receptors are involved in the regulation of tumor growth. T wo progesterone receptor (PR) isoforms have been identified in humans: a la rger form (PR-B) and the N-terminally truncated one (PR-A). PR isoforms can exert opposite functions and are differentially regulated by estrogens. PR have been detected in several brain tumors including chordomas, however, i t is unknown which PR isoform is expressed in brain tumors. The aim of this study was to determine by reverse transcription-polymerase chain reaction (RT-PCR) and by immunohistochemistry the expression pattern of PR isoforms in chordomas as well as its correlation with the expression of estrogen rec eptor alpha (ER-alpha). All studied chordomas expressed both PR and ER-alph a. PR-B was the predominant isoform in chordomas both at the mRNA and at th e protein level. These data suggest that PR-B should be the predominant PR isoform expressed in human chordomas.