Open Access
Scaffold attachment factor B1 regulates androgen degradation pathways in prostate cancer
(E-Century Publishing, 2021) Yang, Julie Suan-Wei; Qian, Chen; You, Sungyong; Rotinen Díaz, Mirja Sofia; Posadas, Edwin M.; Freedland, Stephen J.; Di Vizio, Dolores; Kim, Jayoung; Freeman, Michael R.; Ciencias de la Salud; Osasun Zientziak
The nuclear matrix protein Scaffold Attachment Factor B1 (SAFB1, SAFB) can act in prostate cancer (PCa) as an androgen receptor (AR) co-repressor that functions through epigenetic silencing of AR targets, such as prostate specific antigen (PSA, KLK3). Genomic profiling of SAFB1-silenced PCa cells indicated that SAFB1 may play a role in modulating intracrine androgen levels through the regulation of UDP-glucuronosyltransferase (UGT) genes, which inactivate steroid hormones. Gene silencing of SAFB1 resulted in increased levels of free dihydrotesterosterone (DHT), and increased resistance to the AR inhibitor enzalutamide. SAFB1 silencing suppressed expression of the UDP-glucuronosyltransferase family 2 member B15 gene (UGT2B15) and the closely related UGT2B17 gene, which encode proteins that irreversibly inactivate testosterone (T) and DHT. Analysis of human data indicated that genomic loss at the SAFB locus, or down-regulation of expression of the SAFB gene, is associated with aggressive PCa. These findings identify SAFB1 as an important regulator of androgen catabolism in PCa and suggest that loss or inactivation of this protein may promote AR activity by retention of active androgen in tumor cells.
Open Access
ONECUT2 is a druggable driver of luminal to basal breast cancer plasticity
(Sringer, 2024-05-31) Zamora Álvarez, Irene; Gutiérrez Núñez, Mirian; Pascual, Alex; Pajares Villandiego, María Josefa; Barajas Vélez, Miguel Ángel; Perez, Lillian M.; You, Sungyong; Knudsen, Beatrice S.; Freeman, Michael R.; Encío Martínez, Ignacio; Rotinen Díaz, Mirja Sofia; Ciencias de la Salud; Osasun Zientziak; Institute for Multidisciplinary Research in Applied Biology - IMAB; Gobierno de Navarra / Nafarroako Gobernua
Purpose: tumor heterogeneity complicates patient treatment and can be due to transitioning of cancer cells across phenotypic cell states. This process is associated with the acquisition of independence from an oncogenic driver, such as the estrogen receptor (ER) in breast cancer (BC), resulting in tumor progression, therapeutic failure and metastatic spread. The transcription factor ONECUT2 (OC2) has been shown to be a master regulator protein of metastatic castration-resistant prostate cancer (mCRPC) tumors that promotes lineage plasticity to a drug-resistant neuroendocrine (NEPC) phenotype. Here, we investigate the role of OC2 in the dynamic conversion between different molecular subtypes in BC. Methods: we analyze OC2 expression and clinical significance in BC using public databases and immunohistochemical staining. In vitro, we perform RNA-Seq, RT-qPCR and western-blot after OC2 enforced expression. We also assess cellular effects of OC2 silencing and inhibition with a drug-like small molecule in vitro and in vivo. Results: OC2 is highly expressed in a substantial subset of hormone receptor negative human BC tumors and tamoxifen-resistant models, and is associated with poor clinical outcome, lymph node metastasis and heightened clinical stage. OC2 inhibits ER expression and activity, suppresses a gene expression program associated with luminal differentiation and activates a basal-like state at the gene expression level. We also show that OC2 is required for cell growth and survival in metastatic BC models and that it can be targeted with a small molecule inhibitor providing a novel therapeutic strategy for patients with OC2 active tumors. Conclusions: the transcription factor OC2 is a driver of BC heterogeneity and a potential drug target in distinct cell states within the breast tumors.
Open Access
ONECUT2 acts as a lineage plasticity driver in adenocarcinoma as well as neuroendocrine variants of prostate cancer
(Oxford University Press, 2024-06-27) Qian, Chen; Yang, Qian; Rotinen Díaz, Mirja Sofia; Huang, Rongrong; Kim, Hyoyoung; Gallent, Brad; Yan, Yiwu; Cadaneanu, Radu M.; Zhang, Baohui; Kaochar, Salma; Freedland, Stephen J.; Posadas, Edwin M.; Ellis, Leigh; Di Vizio, Dolores; Morrissey, Colm; Nelson, Peter S.; Brady, Lauren; Murali, Ramachandran; Campbell, Moray J.; Yang, Wei; Knudsen, Beatrice S.; Mostaghel, Elahe A.; Ye, Huihui; Garraway, Isla P.; You, Sungyong; Freeman, Michael R.; Ciencias de la Salud; Osasun Zientziak; Institute for Multidisciplinary Research in Applied Biology - IMAB
Androgen receptor- (AR-) indifference is a mechanism of resistance to hormonal therapy in prostate cancer (PC). Here we demonstrate that ONECUT2 (OC2) activates resistance through multiple drivers associated with adenocarcinoma, stem-like and neuroendocrine (NE) variants. Direct OC2 gene targets include the glucocorticoid receptor (GR; NR3C1) and the NE splicing factor SRRM4, which are key drivers of lineage plasticity. Thus, OC2, despite its previously described NEPC driver function, can indirectly activate a portion of the AR cistrome through epigenetic activation of GR. Mechanisms by which OC2 regulates gene expression include promoter binding, enhancement of genome-wide chromatin accessibility, and super-enhancer reprogramming. Pharmacologic inhibition of OC2 suppresses lineage plasticity reprogramming induced by the AR signaling inhibitor enzalutamide. These results demonstrate that OC2 activation promotes a range of drug resistance mechanisms associated with treatment-emergent lineage variation in PC and support enhanced efforts to therapeutically target OC2 as a means of suppressing treatment-resistant disease.

Rotinen Díaz, Mirja Sofia

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