Expression and hormonal regulation of membrane progesterone receptors in human astrocytoma cells.
Progesterone (P) participates in the regulation of the growth of several tumors, including astrocytomas, the most common and malignant human brain tumors. It has been reported that P induces astrocytomas growth in part by its interaction with its intracellular receptors (PR). Recently, it has been reported that membrane progesterone receptors (mPRs) are expressed in ovarian and breast cancer cells, and that P could exert some actions through these receptors, however, it is unknown whether mPRs are expressed in astrocytomas. In this work, U251 and U87 cell lines derived from human astrocytomas grade IV were used to study the expression, localization and hormonal regulation of three mPRs subtypes. Using RT-qPCR and Western blot techniques, we found that mPRα and mPRβ are clearly expressed at mRNA and protein levels in astrocytoma cells whereas mPRγ was barely expressed in these cells. Immunofluorescence staining showed that mPRα and mPRβ were mainly located in the cell surface. Flow cytometry assays demonstrated that in U251 and U87 cells, mPRβ is expressed by a higher percentage of both permeabilized and non-permeabilized cells as compared with mPRα. The percentage of cells expressing mPRγ was very low. P and estradiol (E) (10, 100 nM and 1 μM) decreased mPRα protein content at 12 h. In contrast, both P (100 nM and 1 μM) and E (10 and 100 nM) increased mPRβ content. Finally, by in silico analysis, we identified that mPRα, mPRβ and mPRγ promoters contain several progesterone and estrogen response elements. Our results indicate that mPRs are expressed in human astrocytoma cells, exhibiting a differential regulation by E and P. These data suggest that some P actions in astrocytoma cells may be mediated by mPRs.
Unidad de Investigación en Reproducción Humana, Instituto Nacional de Perinatología-Facultad de Química, Universidad Nacional Autónoma de México (UNAM), México, D.F., Mexico.
Paulina
P
Valadez-Cosmes
Unidad de Investigación en Reproducción Humana, Instituto Nacional de Perinatología-Facultad de Química, Universidad Nacional Autónoma de México (UNAM), México, D.F., Mexico.
Liliana
L
Germán-Castelán
Departamento de Medicina Genómica y Toxicología Ambiental, Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México, D.F., Mexico.
Aliesha
A
González-Arenas
Facultad de Medicina, UNAM, México, D.F., Mexico.
Marco A
MA
Velasco-Velázquez
Facultad de Química, Departamento de Biología, UNAM, México, D.F., Mexico.
Valeria
V
Hansberg-Pastor
Unidad de Investigación en Reproducción Humana, Instituto Nacional de Perinatología-Facultad de Química, Universidad Nacional Autónoma de México (UNAM), México, D.F., Mexico. Electronic address: camachoarroyo@gmail.com.
Ignacio
I
Camacho-Arroyo
D001254:Astrocytoma / Q000378:metabolism* / Q000473:pathology; D045744:Cell Line, Tumor; D006801:Humans; D008565:Membrane Proteins / Q000378:metabolism*; D011401:Promoter Regions, Genetic; D012333:RNA, Messenger / Q000235:genetics; D011980:Receptors, Progesterone / Q000235:genetics / Q000378:metabolism*
D008565:Membrane Proteins; D012333:RNA, Messenger; D011980:Receptors, Progesterone
Astrocytomas; Brain tumors; Estradiol; Glioblastomas; Membrane progesterone receptors; Progesterone