Astrocytic neoplasms of the central nervous system and orbit: a morphologic perspective

Allopregnanolone promotes proliferation and differential gene expression in human glioblastoma cells

Allopregnanolone (3α-THP) is one of the main reduced progesterone (P₄) metabolites that is recognized as a neuroprotective and myelinating agent. 3α-THP also induces proliferation of different neural cells. It has been shown that P₄ favors the progression of glioblastomas (GBM), the most common and aggressive primary brain tumors. However, the role of 3α-THP in the growth of GBMs is unknown. Here, we studied the effects of 3α-THP on the number of cells, proliferation and gene expression in U87 cell line derived from a human GBM. 3α-THP (10, 100nM and 1μM) increased the number of U87 cells, and at 10nM exerted a similar increase in both the number of total and proliferative U87 cells as compared with P₄ (10nM). Interestingly, finasteride (F; 100nM), an inhibitor of 5α-reductase (5αR), an enzyme necessary to metabolize P₄ and produce 3α-THP, blocked the increase in the number of U87 cells induced by P₄. By using RT-qPCR, we determined that U87 cells express 5α-R isoenzymes 1 and 2 (5αR1 and 5αR2), being 5αR1 the predominant one in these cells. 3α-THP (10nM) increased the expression of TGFβ1, EGFR, VEGF and cyclin D1 genes. P₄ increased TGFβ1 and EGFR expression, and this effect was blocked by F. These data provide evidence that P₄, through its metabolite 3α-THP, can promote in part cell proliferation of human GBM cells by changing the expression of genes involved in tumor progression.

Progesterone induces the growth and infiltration of human astrocytoma cells implanted in the cerebral cortex of the rat

Progesterone (P4) promotes cell proliferation in several types of cancer, including brain tumors such as astrocytomas, the most common and aggressive primary intracerebral neoplasm in humans. In this work, we studied the effects of P4 and its intracellular receptor antagonist, RU486, on growth and infiltration of U373 cells derived from a human astrocytoma grade III, implanted in the motor cortex of adult male rats, using two treatment schemes. In the first one, fifteen days after cells implantation, rats were daily subcutaneously treated with vehicle (propylene glycol, 160  μ L), P4 (1 mg), RU486 (5 mg), or P4 + RU486 (1 mg and 5 mg, resp.) for 21 days. In the second one, treatments started 8 weeks after cells implantation and lasted for 14 days. In both schemes we found that P4 significantly increased the tumor area as compared with the rest of the treatments, whereas RU486 blocked P4 effects. All rats treated with P4 showed tumor infiltration, while 28.6% and 42.9% of the animals treated with RU486 and P4 + RU486, respectively, presented it. Our data suggest that P4 promotes growth and migration of human astrocytoma cells implanted in the motor cortex of the rat through the interaction with its intracellular receptor.