The estrogen receptor signaling pathway activated by phthalates is linked with transforming growth factor-β in the progression of LNCaP prostate cancer models

Abstract

The distinct roles of estrogen receptors (ERs) related with androgen receptors (ARs) have been proposed in prostate cancer, while the involvement of transforming growth factor-β (TGF-β) has been reported in the progression of prostate cancer. In this study, we examined whether the TGF-β signaling pathway is associated with ER signaling in LNCaP prostate cancer cells, which express ERα, ERβ and ARs. We determined whether the exposure to phthalates may induce prostate cancer progression by affecting molecular crosstalk between ER and TGF-β signaling pathways. Cell viability was measured in LNCaP cells by MTT assay following treatment with di-n-buthyl phthalate (DBP). RT-PCR and immunoblot assay were performed to examine the expression levels of cell cycle-related genes and the TGF-β signaling cascade. A mouse xenograft model of prostate cancer was generated, and immunohistochemical and BrdU assay were carried out to determine the effect of DBP in this mouse model. DBP, a type of phthalate, was shown to promote LNCaP cell proliferation by upregulating the gene expression of c-myc and cyclin D1 and by downregulating the expression of p21. DBP significantly reduced the protein expression of p-smad similarly to E2. These regulations caused by DBP were reversed by ICI 182,780, an ER antagonist, indicating that DBP may affect crosstalk between TGF-β and ER signals. In an in vivo mouse model, tumor volume of mice exposed to DBP was increased. Number of cells in S phase of cell cycle was increased by DBP, while expression of p21 protein was reduced in the tissues of DBP-treated mice. These results indicate that DBP may induce the growth of LNCaP prostate cancer by acting on the crosstalk between TGF-β and ER signaling pathways.

Metabolic syndrome, endocrine disruptors and prostate cancer associations: biochemical and pathophysiological evidences

“…Generally, phthalates impair testicular function and have been associated with anti-androgenic effects in humans and recently, in the very few human studies conducted, they were correlated with abdominal obesity and insulin resistance due to their interaction with peroxisome proliferator-activated receptors (PPARs) that regulate lipid and glucose metabolism [57] but more clinical studies about phthalates exposure and MS are needed. As estrogen-like substances, phthalates can induce growth of human hormone dependent prostate cancer cells by acting on the crosstalk between TGF-β and ER signaling pathways [58]. Among common endocrine disruptors, endosulfan (Figure 2) is one of the most studied in oncology; endosulfan is an organochlorine insecticide and acaricide with similar estrogenic effects [59] and maternal exposure to this molecule cause cryptorchidism which is well-known risk factor for testicular cancer [60].…”

Cryoablation induced the change of TGF-β pathway in CWR-22RV prostate cancer cell line

“…In addition to the immunosuppressive roles, TGF-b also could promote EMT and proliferation. Recently, there is a new research found that the estrogen receptor signaling pathway activated by phthalates is linked with TGF-b in progression of LNCCaP prostate cancer models [10]. It has been the research hotspot in tumor domain.…”

Phthalate induced toxicity in prostate cancer cell lines and effects of alpha lipoic acid

“…Contradictory results in the previous studies with LNCaP cell lines and phthalates, raise concerns over more complicated molecular mechanisms behind the mechanism of action of these compounds. DBP at 1 μM treatment induced cell proliferation; (30) while at 50 μM decreased cell proliferation independent from AR expression and activity (31). DEHP induced cytoxicity at 3 mM concentration through induction of reactive oxygen species (ROS) and activation of nuclear p53 and p21 proteins; (60) while this effect was found at much lower concentrations (50 μM) in the study by Hruba et al (31) Experimental and epidemiological evidence for the non-monotonic dose response relationship of endocrine disrupting compounds reveal a need for different strategic methods for the risk assessment of these substance in human health (61).…”

“…DBP was found to promote LN-CaP prostate cancer proliferation through the crosstalk between TGF-β and ER signaling pathway (30). Meanwhile, Hruba et al (31) showed that, at lower concentrations, DEHP (50 μM) and DBP (50 μM) were found to suppress cell cycle proliferation in a dose-dependent manner through induction of accumulation of cells within G1 phase of the cell cycle. Previously, DEHP (3 mM) and its main metabolite MEHP (mono(2-ethylhexyl)phthalate-3 μM) caused production of reactive oxygen species, activation of p53 tumor suppressor and induction of p21WAF/Cip1cyclindependent kinase inhibitor; where this effect was inhibited by selenium (32).…”

“…Overall, it was stated that DEHP and DBP may have negative effects on the proliferation of LNCaP cells, independent of AR modulations. Possible involvement of AR or phenotypic changes such as modulation of neuroendocrine trans differentiation (NED) due to phthalate exposure are still unknown (31). The relationship between phthalate/alpha lipoic acid and male reproduction has recently been studied in an in vivo model.…”