Agonist activation of estrogen receptor beta (ERβ) sensitizes malignant pleural mesothelioma cells to cisplatin cytotoxicity

BACKGROUND: Estrogen receptor (ER) \u3b2 acts as a tumor suppressor in malignant mesotheliomas. METHODS: Here we explored the anti-proliferative and anti-tumorigenic efficacy of the selective ER\u3b2 agonist, KB9520, in human mesothelioma cell lines in vitro and in a mesothelioma mouse model in vivo. RESULTS: KB9520 showed significant anti-proliferative effect in ER\u3b2 positive human malignant pleural mesothelioma cells in vitro. Selective activation of ER\u3b2 with KB9520 sensitized the cells to treatment with cisplatin, resulting in enhanced growth inhibition and increased apoptosis. Furthermore, in CD1 nude mice mesothelioma tumor growth was significantly inhibited when KB9520 was added on top of the standard of care chemo combination cisplatin/pemetrexed, as compared to the cisplatin/pemetrexed alone group. Importantly, KB9520 exerted a protective effect to cisplatin toxicity in the non-malignant mesothelium derived MET5A cells. CONCLUSIONS: Together, the data presented suggest that selective targeting of ER\u3b2 may be an efficacious stand-alone treatment option and/or become an important add-on to existing malignant mesothelioma therapy

Perifosine as a Potential Novel Anti-Cancer Agent Inhibits EGFR/MET-AKT Axis in Malignant Pleural Mesothelioma

PI3K/AKT signalling pathway is aberrantly active and plays a critical role for cell cycle progression of human malignant pleural mesothelioma (MMe) cells. AKT is one of the important cellular targets of perifosine, a novel bio-available alkylphospholipid that has displayed significant anti-proliferative activity in vitro and in vivo in several human tumour model systems and is currently being tested in clinical trials.We tested Perifosine activity on human mesothelial cells and different mesothelioma cell lines, in order to provide evidence of its efficacy as single agent and combined therapy.We demonstrate here that perifosine, currently being evaluated as an anti-cancer agent in phase 1 and 2 clinical trials, caused a dose-dependent reduction of AKT activation, at concentrations causing MMe cell growth arrest. In this study we firstly describe that MMe cells express aside from AKT1 also AKT3 and that either the myristoylated, constitutively active, forms of the two proteins, abrogated perifosine-mediated cell growth inhibition. Moreover, we describe here a novel mechanism of perifosine that interferes, upstream of AKT, affecting EGFR and MET phosphorylation. Finally, we demonstrate a significant increase in cell toxicity when MMe cells were treated with perifosine in combination with cisplatin.This study provides a novel mechanism of action of perifosine, directly inhibiting EGFR/MET-AKT1/3 axis, providing a rationale for a novel translational approach to the treatment of MMe

Intracellular lactate-mediated induction of estrogen receptor beta (ER\u3b2) in biphasic malignant pleural mesothelioma cells

Biphasic malignant pleural mesothelioma (MPM) is the second most common histotype of MPM. It is histologically characterized by the concomitant presence of epithelioid and sarcomatoid features, the latter associated with worse prognosis.In this report we describe that silencing of AKT1 in spindle-shaped biphasic MPM cells promotes the shift toward an epithelioid phenotype. Furthermore, AKT1 silencing resulted in decreased expression of the lactate/H+ symporter MCT4 and its chaperone CD147/Basigin, and in the induction of estrogen receptor \u3b2 (ER\u3b2) expression. We provide evidence that ER\u3b2 expression is induced by increased intracellular lactate concentration. Spheroid culturing and tumor growth of ER\u3b2 negative biphasic MPM in nude mice resulted in the induction of ER\u3b2 expression and response to the selective agonist KB9520. In both models, the treatment with the ER\u3b2 agonist results in reduced cell proliferation, decreased expression of MCT4 and CD147/Basigin and increased acetylation and inactivation of AKT1. Collectively, in response to metabolic changes, ER\u3b2 expression is induced and exerts an anti-tumor effect through selective agonist activation. The possibility to reverse the more aggressive biphasic mesothelioma histotype by targeting ER\u3b2 with a selective agonist could represent a new effective treatment strategy

KDM6B histone demethylase is an epigenetic regulator of estrogen receptor \u3b2 expression in human pleural mesothelioma

AIM: To assess the correlation between KDM6B and estrogen receptor \u3b2 (ER\u3b2) expression in malignant pleural mesothelioma (MPM). MATERIALS & METHODS: We evaluated gene expression by in silico analysis of microarray data, real-time PCR and western blot in MPM tumors and cell lines. RESULTS & CONCLUSION: We report a strong positive correlation between the expression of KDM6B and ER\u3b2 in MPM tumors and cell lines. We describe that, in hypoxia, the HIF2\u3b1-KDM6B axis induces an epithelioid morphology and ER\u3b2 expression in biphasic MPM cells with estrogen receptor-negative phenotype. Reduced histone H3K27 tri-methylation confirms KDM6B activity under hypoxic conditions. Importantly, cells treated during reoxygenation with the selective ER\u3b2 agonist, KB9520, maintain ER\u3b2 expression and the less aggressive phenotype acquired in hypoxia

SIRT1 at the crossroads of AKT1 and ERβ in malignant pleural mesothelioma cells

In this report, we show that malignant pleural mesothelioma (MPM) patients whose tumors express high levels of AKT1 exhibit a significantly worse prognosis, whereas no significant correlation with AKT3 expression is observed. We provide data that establish a phosphorylation independent role of AKT1 in affecting MPM cell shape and anchorage independent cell growth in vitro and highlight the AKT1 isoform-specific nature of these effects. We describe that AKT1 activity is inhibited by the loss of SIRT1-mediated deacetylation and identify, by mass spectrometry, 11 unique proteins that interact with acetylated AKT1. Our data demonstrate a role of the AKT1/SIRT1/FOXM1 axis in the expression of the tumor suppressor ERβ. We further demonstrate an inhibitory feedback loop by ERβ, activated by the selective agonist KB9520, on this axis both in vitro and in vivo. Our data broaden the current knowledge of ERβ and AKT isoform-specific functions that could be valuable in the design of novel and effective therapeutic strategies for MPM