title: Membrane progesterone receptor alpha as a potential prognostic biomarker for breast cancer survival: a retrospective study.
abstract: Classically, the actions of progesterone (P4) are attributed to the binding of nuclear progesterone receptor (PR) and subsequent activation of its downstream target genes. These mechanisms, however, are not applicable to PR- or basal phenotype breast cancer (BPBC) due to lack of PR in these cancers. Recently, the function of membrane progesterone receptor alpha (mPRα) in human BPBC cell lines was studied in our lab. We proposed that the signaling cascades of P4→mPRα pathway may play an essential role in controlling cell proliferation and epithelial mesenchymal transition (EMT) of breast cancer. Using human breast cancer tissue microarrays, we found in this study that the average intensity of mPRα expression, but not percentage of breast cancer with high level of mPRα expression (mPRα-HiEx), was significantly lower in the TNM stage 4 patients compared to those with TNM 1-3 patients; and both average intensities of mPRα expression and mPRα-HiEx rates were significantly higher in cancers negative for ER, as compared with those cancers with ER+. However, after adjusting for age at diagnosis and/or TNM stage, only average intensities of mPRα expression were associated with ER status. In addition, we found that the rates of mPRα-HiEx were significantly higher in cancers with epithelial growth factor receptor-1 (EGFR+) and high level of Ki67 expression, indicating positive correlation between mPRα over expression and EGFR or Ki67. Further analysis indicated that both mPRα-HiEx rate and average intensity of mPRα expression were significantly higher in HER2+ subtype cancers (i.e. HER2+ER-PR-) as compared to ER+ subtype cancers. These data support our hypothesis that P4 modulates the activities of the PI3K and cell proliferation pathways through the caveolar membrane bound growth factor receptors such as mPRα and growth factor receptors. Future large longitudinal studies with larger sample size and survival outcomes are necessary to confirm our findings.
authors.affiliation: Histopathology core, Atlanta Research & Educational Foundation/Atlanta VA Medical Center, Decatur, Georgia, United States of America.
authors.forename: Mingxuan
authors.initials: M
authors.lastname: Xie
authors.forename: Xiangzhu
authors.initials: X
authors.lastname: Zhu
authors.forename: Zhaofan
authors.initials: Z
authors.lastname: Liu
authors.forename: Martha
authors.initials: M
authors.lastname: Shrubsole
authors.forename: Vijay
authors.initials: V
authors.lastname: Varma
authors.forename: Ingrid A
authors.initials: IA
authors.lastname: Mayer
authors.forename: Qi
authors.initials: Q
authors.lastname: Dai
authors.forename: Qiong
authors.initials: Q
authors.lastname: Chen
authors.forename: Shaojin
authors.initials: S
authors.lastname: You
mesh_terms: D014408:Biomarkers, Tumor / Q000032:analysis / Q000378:metabolism*; D001943:Breast Neoplasms / Q000378:metabolism / Q000401:mortality* / Q000473:pathology; D002277:Carcinoma / Q000401:mortality* / Q000473:pathology; D066246:ErbB Receptors / Q000032:analysis; D005260:Female; D006801:Humans; D019394:Ki-67 Antigen / Q000032:analysis; D008875:Middle Aged; D009367:Neoplasm Staging; D011374:Progesterone / Q000378:metabolism; D011379:Prognosis; D011960:Receptors, Estrogen / Q000032:analysis; D011980:Receptors, Progesterone / Q000032:analysis / Q000378:metabolism*; D012189:Retrospective Studies
chemical_list: D014408:Biomarkers, Tumor; D019394:Ki-67 Antigen; D011960:Receptors, Estrogen; D011980:Receptors, Progesterone; C101118:progesterone receptor A; D011374:Progesterone; C512478:EGFR protein, human; D066246:ErbB Receptors