Estrogen-induced growth inhibition of human seminoma cells expressing estrogen receptor β and aromatase

Abstract

It is now well established that estrogens participate in the control of normal spermatogenesis and endogenous or environmental estrogens are involved in pathological germ cell proliferation including testicular germ cell tumors. Studying a human testicular seminoma cell line, JKT-1, we show here that 17 -estradiol (10 −12 to 10 −6 M) induced in vitro a significant dose-dependent decrease of cell growth. This antiproliferative effect was maximum after 4 days of exposure at a physiologically intratesticular concentration of 10 −9 M, close to the K d of ER, and reversed by ICI 182780, an ER antagonist, suggesting an ER-mediated pathway. By RT-PCR and Western blot we were able to confirm that JKT-1, like tumoral seminoma cells and normal human testicular basal germ cells, expresses estrogen receptor (ER ), including ER 1 and ER 2, a dominant negative variant, but not ER . Using immunofluorescence and confocal microscopy, ER was observed as perinuclear intracytoplasmic spots in JKT-1 and tumoral seminoma cells without significant translocation of ER into the nucleus, under 17 -estradiol exposure. Double staining observed by confocal microscopy revealed that ER colocalized in JKT-1 cells with cytochrome C, a mitochondrial marker. We report for the first time the expression of a functional aromatase complex in seminoma cells as assessed by RT-PCR, Western blot and enzymatic assay. Seminoma cells are able to respond to estrogens through a possible autocrine or paracrine loop. These preliminary results support estrogen-dependency of human testicular seminoma, the most frequent tumor of young men, and suggest potential pharmacological use. Whether this estrogen control, however, involves an ER -mediated stimulation of cell apoptosis and/or an ER -mediated inhibition of cell proliferation, remains to be further determined.

Estrogen receptor beta (ERβ) produces autophagy and necroptosis in human seminoma cell line through the binding of the Sp1 on the phosphatase and tensin homolog deleted from chromosome 10 (PTEN) promoter gene

“…Therefore, ERβ, via PTEN, inhibits cell survival, suggesting a collaborative role of these two proteins in mediating E2 action in human seminoma cell line, consistent with the current belief that ERβ may be antiproliferative and tumor-suppressive. 12 In fact, ERα overexpression induced the AKT content, supporting the hypothesis that the presence of ERα is associated with the proliferative effects of estrogens. 36 Reduced AKT activity may induce cell death through apoptosis; however, in our cells, the expression of proapoptotic proteins such as FKHR1, BID and BAX was faint.…”

“…11 Conversely, E2 inhibits human embryonal carcinoma cell proliferation in vitro through an ERβ-dependent mechanism. 12 In human testis, gonocytes and adult germ cells 13 mainly express ERβ, while ERβ loss is associated with advanced tumor stage in several cancers. 14 However, the precise role of estrogens/ERs in the biology of TGCTs remains to be determined.…”

Estrogen receptors and function in the male reproductive system

“…In humans, ESR2, but not ESR1 and androgen receptor (AR), is expressed in gonocytes and spermatogonia (29). It is worth to mention that ESR2 is coexpressed with ESR1 in tumoral seminoma cells, where it may counteract the tumor cell proliferation mediated by ESR1 (30).…”

Cancer stem cells as targets for cancer therapy: selected cancers as examples

“…These cell lines are JKT-1 [70,81,90,146] and TCam-2 [59,89]. Gene expression and immunohistochemical profiling have shown that only the TCam-2 cell line is representative for seminoma (Fig.…”