Breast cancer (BC) is the primary cause of cancer-related mortality among women. Patients who express the estrogen receptor (ER), which mediates the tumorigenic effects of estrogens, respond to antihormonal therapy. Loss of ER expression or acquired resistance to E2 is associated with aggressive malignant phenotypes, which lead to relapse. These BC subtypes overexpress syndecan-1 (SDC1), a transmembrane heparan sulfate proteoglycan that mediates angiogenesis as well as the proliferation and invasiveness of cancer cells. We showed here that the activation of ER-alpha (ERα) by estrogens induces downregulation of SDC1 expression in ER(+) MCF7 cells but not in T47D cells. Loss of ERα expression, induced by RNA interference or a selective ER downregulator, led to subsequent SDC1 overexpression. E2-dependent downregulation of SDC1 expression required de novo protein synthesis and was antagonized by treatment with BAY 11-7085, an irreversible inhibitor of IκBα phosphorylation, which inhibits the activation of NFκB. Downregulation of SDC1 expression required ERα and activation of IKK, but was independent to downstream transcriptional regulators of NFκB. BAY 11-7085 prevented E2-mediated phosphorylation of ERα on Ser118, increasing its proteasomal degradation, suggesting that IKK stabilized E2-activated ERα, leading to subsequent downregulation of SDC1 expression. Our results showed that sustained ER signaling inhibits SDC1 expression. Such antagonism elucidates the inverse correlation between SDC1 and ER expression in ER(+) BC as well as the overexpression of SDC1 in hormone receptor-negative BC subtypes with the most aggressive phenotypes. These results identify SDC1 as an attractive therapeutic target for BC as well as for other endocrine-associated cancers.

Cancer treatments such as chemotherapy can have gonadotoxic effects. In order to preserve and restore the fertility of prepubertal patients with cancer, testicular biopsies are frozen and could theoretically be later matured in vitro to produce spermatozoa for assisted reproductive technology. A complete in vitro spermatogenesis has been obtained from prepubertal testicular tissue in the mouse model, although the sperm yield was low. Since steroid hormones play an essential role in spermatogenesis, it appears necessary to ensure that their synthesis and mechanisms of action are not altered in in vitro cultured tissues. The aim of this study was therefore to investigate steroidogenesis as well as androgen and estrogen signaling during in vitro maturation of mouse prepubertal testicular tissues. Histological, RT-qPCR, Western blot analyses, measurements of cholesterol, steroid hormones levels and aromatase activity were performed on fresh or frozen/thawed in vitro cultured mouse testicular tissues from 6.5 days postpartum (dpp) mice as well as on age-matched in vivo controls. A similar density of Leydig cells (LC) was found after 30 days of organotypic culture (D30) and at 36.5 dpp, the corresponding in vivo time point. However, LC were partially mature after in vitro culture, with decreased Sult1e1 and Insl3 mRNA levels (adult LC markers). Moreover, the transcript levels of Cyp11a1, Cyp17a1 and Hsd17b3 encoding steroidogenic enzymes were decreased in vitro. Increased amounts of progesterone and estradiol and reduced androstenedione intratesticular levels were observed at D30. Furthermore, androgen signaling was altered at D30, with decreased transcript levels of androgen target genes (Rhox5, Septin12). Moreover, the expression and activity of aromatase and estrogen signaling were impaired at D30. The addition of hCG to the organotypic culture medium induced an elevation in androgen production but did not improve sperm yield. In conclusion, this study reports partial LC maturation, disturbed steroidogenic activity of LC, abnormal steroid hormone content as well as altered androgen and estrogen signaling in cultures of fresh and frozen/thawed prepubertal mouse testicular tissues. The organotypic culture system will need to be further improved to increase the efficiency of in vitro spermatogenesis and allow a clinical application.

Cancer treatments such as chemotherapy can have gonadotoxic effects. In order to preserve and restore the fertility of prepubertal patients with cancer, testicular biopsies are frozen and could theoretically be later matured in vitro to produce spermatozoa for assisted reproductive technology. A complete in vitro spermatogenesis has been obtained from prepubertal testicular tissue in the mouse model, although the sperm yield was low. Since steroid hormones play an essential role in spermatogenesis, it appears necessary to ensure that their synthesis and mechanisms of action are not altered in in vitro cultured tissues. The aim of this study was therefore to investigate steroidogenesis as well as androgen and estrogen signaling during in vitro maturation of mouse prepubertal testicular tissues. Histological, RT-qPCR, Western blot analyses, measurements of cholesterol, steroid hormones levels and aromatase activity were performed on fresh or frozen/thawed in vitro cultured mouse testicular tissues from 6.5 days postpartum (dpp) mice as well as on age-matched in vivo controls. A similar density of Leydig cells (LC) was found after 30 days of organotypic culture (D30) and at 36.5 dpp, the corresponding in vivo time point. However, LC were partially mature after in vitro culture, with decreased Sult1e1 and Insl3 mRNA levels (adult LC markers). Moreover, the transcript levels of Cyp11a1, Cyp17a1 and Hsd17b3 encoding steroidogenic enzymes were decreased in vitro. Increased amounts of progesterone and estradiol and reduced androstenedione intratesticular levels were observed at D30. Furthermore, androgen signaling was altered at D30, with decreased transcript levels of androgen target genes (Rhox5, Septin12). Moreover, the expression and activity of aromatase and estrogen signaling were impaired at D30. The addition of hCG to the organotypic culture medium induced an elevation in androgen production but did not improve sperm yield. In conclusion, this study reports partial LC maturation, disturbed steroidogenic activity of LC, abnormal steroid hormone content as well as altered androgen and estrogen signaling in cultures of fresh and frozen/thawed prepubertal mouse testicular tissues. The organotypic culture system will need to be further improved to increase the efficiency of in vitro spermatogenesis and allow a clinical application.