Identification of Androgen Receptor Metabolic Correlome Reveals the Repression of Ceramide Kinase by Androgens

Prostate cancer (PCa) is one of the most prevalent cancers in men. Androgen receptor signaling plays a major role in this disease, and androgen deprivation therapy is a common therapeutic strategy in recurrent disease. Sphingolipid metabolism plays a central role in cell death, survival, and therapy resistance in cancer. Ceramide kinase (CERK) catalyzes the phosphorylation of ceramide to ceramide 1-phosphate, which regulates various cellular functions including cell growth and migration. Here we show that activated androgen receptor (AR) is a repressor of CERK expression. We undertook a bioinformatics strategy using PCa transcriptomics datasets to ascertain the metabolic alterations associated with AR activity. CERK was among the most prominent negatively correlated genes in our analysis. Interestingly, we demonstrated through various experimental approaches that activated AR reduces the mRNA expression of CERK: (i) expression of CERK is predominant in cell lines with low or negative AR activity; (ii) AR agonist and antagonist repress and induce CERK mRNA expression, respectively; (iii) orchiectomy in wildtype mice or mice with PCa (harboring prostate-specific Pten deletion) results in elevated Cerk mRNA levels in prostate tissue. Mechanistically, we found that AR represses CERK through interaction with its regulatory elements and that the transcriptional repressor EZH2 contributes to this process. In summary, we identify a repressive mode of AR that influences the expression of CERK in PCa.A.G.-M. is funded by the MINECO (SAF2016-79695-R) and the department of education (IKERTALDE IT1106-16). V.T. is funded by Fundación Vasca de Innovación e Investigación Sanitarias, BIOEF (BIO15/CA/052), the AECC J.P. Bizkaia and the Basque Department of Health (2016111109) and the MINECO RTI2018-097267-B-I00. The work of A. Carracedo is supported by the Basque Department of Industry, Tourism and Trade (Elkartek), the department of education (IKERTALDE IT1106-16) and health (RIS3), the MICINN (PID2019-108787RB-I00 (FEDER/EU); Severo Ochoa Excellence Accreditation SEV-2016-0644; Excellence Networks RED2018-102769-T), the AECC (GCTRA18006CARR), La Caixa Foundation (ID 100010434), under the agreement LCF/PR/HR17/ and the European Research Council (Consolidator Grant 819242). CIBERONC was co-funded with FEDER funds and funded by ISCIII

Regulation of macrophage and preadipocyte proliferation and migration by C1P

154 p.Chronic inflammatory diseases are the most significant cause of death in the world. Indeed, according to the World Health Organization (WHO), 3 out of 5 people die due to chronic inflammatory diseases such as stroke, chronic respiratory diseases, heart disorders, cancer, obesity or diabetes. It has been demonstrated that sphingolipid metabolism is altered in this type of disorders. Therefore, understanding the molecular mechanisms by which bioactive sphingolipids participate in the establishment or progression of those diseases may be useful for developing novel therapeutic strategies to control them. In the first chapter of this thesis, we demonstrate that the bioactive sphingolipid ceramide 1-phosphate (C1P) induces survival, proliferation and migration of preadipocytes through mechanisms that implicate the PI3K/Akt, MEK/ERK1-2 and JAK/STAT3 signaling pathways. These biological actions suggest a possible role of this phosphosphingolipid in fat accumulation and dysfunction of adipose tissue, which might lead to metabolic diseases, most notably, obesity. In the second chapter we show that exogenous C1P inhibits alveolar macrophage migration, an action that seems to be caused by dephosphorylation of important proteins that are involved in the regulation of cell migration, such as, PKB/Akt, ERK1-2, PAK1 and Paxillin. In addition, the latter study provides evidence that granular nanosized silica (SiO2)-conditioned medium enhances alveolar macrophage migration through activation of PI3K/Akt signaling cascade and that C1P inhibits this action by blocking PKB/Akt phosphorylation. Taken together, the results of this thesis support the notion that C1P may have anti-inflammatory properties in lung cells