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Steroid hormones, including progestagens, estrogens, androgens, corticosteroids, and their precursor cholesterol, perform essential functions in the successful establishment and maintenance of pregnancy and normal fetal development. As the core endocrine organ at the prenatal stage, the human placenta is involved in the biosynthesis, metabolism, and delivery of steroid hormones. Steroidogenic pathways are tightly regulated by placenta-intrinsic cytochrome P450 and hydroxysteroid dehydrogenase. However, the relationship between placental steroidogenic enzyme expression and adverse pregnancy outcomes is controversial. In this review, we summarize the possible upstream regulatory mechanisms of placental steroidogenic enzymes in physiologic and pathophysiologic states. We also describe the human placental barrier model and examine the potential of single-cell sequencing for evaluating the primary functions and cellular origin of steroidogenic enzymes. Finally, we examine the existing evidence for the association between placental steroidogenic enzyme dysregulation and adverse pregnancy outcomes.

Cancer-associated fibroblasts (CAFs) play a vital role in malignant transformation and progression of prostate cancer (PCa), and accumulating evidence suggests an enhancing effect of estrogens on PCa. The present study aimed to investigate the possible origin of prostate CAFs and the effects of estrogen receptors, G protein-coupled receptor 30 (GPR30) and estrogen receptor (ER)-α, on stromal cell activation. High expression of fibroblast activation protein (FAP), CD44, and nonmuscle myosin heavy chain B (SMemb) accompanied by low expression of smooth muscle differentiation markers was found in the stromal cells of PCa tissues and in cultured human prostate CAFs. Additionally, SMemb expression, which is coupled to cell phenotype switching and proliferation, was coexpressed with FAP, a marker of activated stromal cells, and with the stem cell marker CD44 in the stromal cells of PCa tissue. Prostate CAFs showed high GPR30 and low ERα expression. Moreover, GPR30 was coexpressed with FAP, CD44, and SMemb. Furthermore, the study demonstrated that the overexpression of GPR30 or the knockdown of ERα in prostate stromal cells induced the up-regulation of FAP, CD44, Smemb, and the down-regulation of smooth muscle markers. The conditioned medium from these cells promoted the proliferation and migration of LNCaP and PC3 PCa cells. GPR30 knockdown or ERα overexpression showed opposite effects. Finally, we present a novel mechanism whereby GPR30 limits ERα expression via inhibition of the cAMP/protein kinase A signaling pathway. These results suggest that stem-like cells within the stroma are a possible source of prostate CAFs and that the negative regulation of ERα expression by GPR30 is centrally involved in prostate stromal cell activation.