Splicing machinery dysregulation drives glioblastoma development/aggressiveness: oncogenic role of SRSF3.

Glioblastomas remain the deadliest brain tumour, with a dismal ∼12-16-month survival from diagnosis. Therefore, identification of new diagnostic, prognostic and therapeutic tools to tackle glioblastomas is urgently needed. Emerging evidence indicates that the cellular machinery controlling the splicing process (spliceosome) is altered in tumours, leading to oncogenic splicing events associated with tumour progression and aggressiveness. Here, we identify for the first time a profound dysregulation in the expression of relevant spliceosome components and splicing factors (at mRNA and protein levels) in well characterized cohorts of human high-grade astrocytomas, mostly glioblastomas, compared to healthy brain control samples, being SRSF3, RBM22, PTBP1 and RBM3 able to perfectly discriminate between tumours and control samples, and between proneural-like or mesenchymal-like tumours versus control samples from different mouse models with gliomas. Results were confirmed in four additional and independent human cohorts. Silencing of SRSF3, RBM22, PTBP1 and RBM3 decreased aggressiveness parameters in vitro (e.g. proliferation, migration, tumorsphere-formation, etc.) and induced apoptosis, especially SRSF3. Remarkably, SRSF3 was correlated with patient survival and relevant tumour markers, and its silencing in vivo drastically decreased tumour development and progression, likely through a molecular/cellular mechanism involving PDGFRB and associated oncogenic signalling pathways (PI3K-AKT/ERK), which may also involve the distinct alteration of alternative splicing events of specific transcription factors controlling PDGFRB (i.e. TP73). Altogether, our results demonstrate a drastic splicing machinery-associated molecular dysregulation in glioblastomas, which could potentially be considered as a source of novel diagnostic and prognostic biomarkers as well as therapeutic targets for glioblastomas. Remarkably, SRSF3 is directly associated with glioblastoma development, progression, aggressiveness and patient survival and represents a novel potential therapeutic target to tackle this devastating pathology.

A New Generation Somatostatin-Dopamine Analogue Exerts Potent Antitumoral Actions on Pituitary Neuroendocrine Tumor Cells.

BACKGROUND: Pituitary neuroendocrine tumors (PitNETs) represent approximately 15% of all intracranial tumors and usually are associated with severe comorbidities. Unfortunately, a relevant number of patients do not respond to currently available pharmacological treatments, that is, somatostatin analogs (SSAs) or dopamine-agonists (DA). Thus, novel, chimeric somatostatin/dopamine compounds (dopastatins) that could improve medical treatment of PitNETs have been designed. OBJECTIVE: This study aims to determine the direct therapeutic effects of a new-generation dopastatin, BIM-065, on primary cell cultures from different PitNETs subtypes. METHODS: Thirty-one PitNET-derived cell cultures (9 corticotropinomas, 9 somatotropinomas, 11 nonfunctioning pituitary adenomas [NFPAs], and 2 prolactinomas), were treated with BIM-065, and key functional endpoints were assessed (cell viability, apoptosis, hormone secretion, expression levels of key genes, free cytosolic [Ca2+]i dynamics, etc.). AtT-20 cell line was used to evaluate signaling pathways in response to BIM-065. RESULTS: This chimeric compound decreased cell viability in all corticotropinomas and somatotropinomas tested, but not in NFPAs. BIM-065 reduced ACTH, GH, chromogranin-A and PRL secretion, and increased apoptosis in corticotropinomas, somatotropinomas, and NFPAs. These effects were possibly mediated through modulation of pivotal signaling cascades like [Ca2+]i kinetic and Akt- or ERK1/2-phosphorylation. CONCLUSIONS: Our results unveil a robust antitumoral effect in vitro of the novel chimeric compound BIM-065 on the main PitNET subtypes, inform on the mechanisms involved, and suggest that BIM-065 could be an efficacious therapeutic option to be considered in the treatment of PitNETs.

Statins Directly Regulate Pituitary Cell Function and Exert Antitumor Effects in Pituitary Tumors.

INTRODUCTION: Pituitary neuroendocrine tumors (PitNETs), the most abundant of all intracranial tumors, entail severe comorbidities. First-line therapy is transsphenoidal surgery, but subsequent pharmacological therapy is often required. Unfortunately, many patients are/become unresponsive to available drugs (somatostatin analogues [SSAs]/dopamine agonists), underscoring the need for new therapies. Statins are well-known drugs commonly prescribed to treat hyperlipidemia/cardiovascular diseases, but can convey additional beneficial effects, including antitumor actions. The direct effects of statins on normal human pituitary or PitNETs are poorly known. Thus, we aimed to explore the direct effects of statins, especially simvastatin, on key functional parameters in normal and tumoral pituitary cells, and to evaluate the combined effects of simvastatin with metformin (MF) or SSAs. METHODS: Effects of statins in cell proliferation/viability, hormone secretion, and signaling pathways were evaluated in normal pituitary cells from a primate model (Papio anubis), tumor cells from corticotropinomas, somatotropinomas, nonfunctioning pituitary tumors, and PitNET cell-lines (AtT20/GH3-cells). RESULTS: All statins decreased AtT20-cell proliferation, simvastatin showing stronger effects. Indeed, simvastatin reduced cell viability and/or hormone secretion in all PitNETs subtypes and cell-lines, and ACTH/GH/PRL/FSH/LH secretion (but not expression), in primate cell cultures, by modulating MAPK/PI3K/mTOR pathways and expression of key receptors (GH-releasing hormone-receptor/ghrelin-R/Kiss1-R) regulating pituitary function. Addition of MF or SSAs did not enhance simvastatin antitumor effects. CONCLUSION: Our data reveal direct antitumor effects of simvastatin on PitNET-cells, paving the way to explore these compounds as a possible tool to treat PitNETs.

The oncogenic role of the spliced somatostatin receptor sst5TMD4 variant in prostate cancer.

sst5TMD4, a splice variant of the sst5 gene, is overexpressed and associated with aggressiveness in various endocrine-related tumors, but its presence, functional role, and mechanisms of actions in prostate cancer (PCa)-the most common cancer type in males-is completely unexplored. In this study, formalin-fixed, paraffin-embedded prostate pieces from patients with localized PCa, which included tumoral and nontumoral adjacent regions (n = 45), fresh biopsies from patients with high-risk PCa (n = 52), and healthy fresh prostates from cystoprostatectomies (n = 14) were examined. In addition, PCa cell lines and xenograft models were used to determine the presence and functional role of sst5TMD4. Results demonstrated that sst5TMD4 is overexpressed (mRNA/protein) in PCa samples, and this is especially drastic in metastatic and/or high Gleason score tumor samples. Remarkably, sst5TMD4 expression was associated with an altered frequency of 2 single-nucleotide polymorphisms: rs197055 and rs12599155. In addition, PCa cell lines and xenograft models were used to demonstrate that sst5TMD4 overexpression increases cell proliferation and migration in PCa cells and induces larger tumors in nude mice, whereas its silencing decreased proliferation and migration. Remarkably, sst5TMD4 overexpression activated multiple intracellular pathways (ERK/JNK, MYC/MAX, WNT, retinoblastoma), altered oncogenes and tumor suppressor gene expression, and disrupted the normal response to somatostatin analogs in PCa cells. Altogether, we demonstrate that sst5TMD4 is overexpressed in PCa, especially in those patients with a worse prognosis, and plays an important pathophysiologic role in PCa, which suggesting its potential as a biomarker and/or therapeutic target.-Hormaechea-Agulla, D., Jiménez-Vacas, J. M., Gómez-Gómez, E., L.-López, F., Carrasco-Valiente, J., Valero-Rosa, J., Moreno, M. M., Sánchez-Sánchez, R., Ortega-Salas, R., Gracia-Navarro, F., Culler, M. D., Ibáñez-Costa, A., Gahete, M. D., Requena, M. J., Castaño, J. P., Luque, R. M. The oncogenic role of the spliced somatostatin receptor sst5TMD4 variant in prostate cancer.

Obesity and metabolic dysfunction severely influence prostate cell function: role of insulin and IGF1.

Obesity is a major health problem that courses with severe comorbidities and a drastic impairment of homeostasis and function of several organs, including the prostate gland (PG). The endocrine-metabolic regulatory axis comprising growth hormone (GH), insulin and IGF1, which is drastically altered under extreme metabolic conditions such as obesity, also plays relevant roles in the development, modulation and homeostasis of the PG. However, its implication in the pathophysiological interplay between obesity and prostate function is still to be elucidated. To explore this association, we used a high fat-diet obese mouse model, as well as in vitro primary cultures of normal-mouse PG cells and human prostate cancer cell lines. This approach revealed that most of the components of the GH/insulin/IGF1 regulatory axis are present in PGs, where their expression pattern is altered under obesity conditions and after an acute insulin treatment (e.g. Igfbp3), which might have some pathophysiological implications. Moreover, our results demonstrate, for the first time, that the PG becomes severely insulin resistant under diet-induced obesity in mice. Finally, use of in vitro approaches served to confirm and expand the conception that insulin and IGF1 play a direct, relevant role in the control of normal and pathological PG cell function. Altogether, these results uncover a fine, germane crosstalk between the endocrine-metabolic status and the development and homeostasis of the PG, wherein key components of the GH, insulin and IGF1 axes could play a relevant pathophysiological role.

The oncogenic role of the In1-ghrelin splicing variant in prostate cancer aggressiveness.

BACKGROUND: The Ghrelin-system is a complex, pleiotropic family composed of several peptides, including native-ghrelin and its In1-ghrelin splicing variant, and receptors (GHSR 1a/b), which are dysregulated in various endocrine-related tumors, where they associate to pathophysiological features, but the presence, functional role, and mechanisms of actions of In1-ghrelin splicing variant in prostate-cancer (PCa), is completely unexplored. Herein, we aimed to determine the presence of key ghrelin-system components (native-ghrelin, In1-ghrelin, GHSR1a/1b) and their potential pathophysiological role in prostate cancer (PCa). METHODS: In1-ghrelin and native-ghrelin expression was evaluated by qPCR in prostate tissues from patients with high PCa-risk (n = 52; fresh-tumoral biopsies), and healthy-prostates (n = 12; from cystoprostatectomies) and correlated with clinical parameters using Spearman-test. In addition, In1-ghrelin and native-ghrelin was measured in plasma from an additional cohort of PCa-patients with different risk levels (n = 30) and control-healthy patients (n = 20). In vivo functional (proliferation/migration) and mechanistic (gene expression/signaling-pathways) assays were performed in PCa-cell lines in response to In1-ghrelin and native-ghrelin treatment, overexpression and/or silencing. Finally, tumor progression was monitored in nude-mice injected with PCa-cells overexpressing In1-ghrelin, native-ghrelin and empty vector (control). RESULTS: In1-ghrelin, but not native-ghrelin, was overexpressed in high-risk PCa-samples compared to normal-prostate (NP), and this expression correlated with that of PSA. Conversely, GHSR1a/1b expression was virtually absent. Remarkably, plasmatic In1-ghrelin, but not native-ghrelin, levels were also higher in PCa-patients compared to healthy-controls. Furthermore, In1-ghrelin treatment/overexpression, and to a much lesser extent native-ghrelin, increased aggressiveness features (cell-proliferation, migration and PSA secretion) of NP and PCa cells. Consistently, nude-mice injected with PC-3-cells stably-transfected with In1-ghrelin, but not native-ghrelin, presented larger tumors. These effects were likely mediated by ERK1/2-signaling activation and involved altered expression of key oncogenes/tumor suppressor genes. Finally, In1-ghrelin silencing reduced cell-proliferation and PSA secretion from PCa cells. CONCLUSIONS: Altogether, our results indicate that In1-ghrelin levels (in tissue) and circulating levels (in plasma) are increased in PCa where it can regulate key pathophysiological processes, thus suggesting that In1-ghrelin may represent a novel biomarker and a new therapeutic target in PCa.

Lack of cortistatin or somatostatin differentially influences DMBA-induced mammary gland tumorigenesis in mice in an obesity-dependent mode.

BACKGROUND: Somatostatin (SST) and cortistatin (CORT), two structurally and functionally related peptides, share a family of widespread receptors (sst1-5) to exert apparently similar biological actions, including endocrine/metabolic regulation and suppression of tumor cell proliferation. However, despite their therapeutic potential, attempts to apply SST-analogs to treat breast cancer have yielded unsatisfactory results. Actually, the specific roles of SST and CORT in mammary gland tumorigenesis (MGT), particularly in relation to metabolic dysregulation (i.e. obesity), remain unknown. METHODS: The role of endogenous SST and CORT in carcinogen-induced MGT was investigated under normal (lean) and obesity conditions. To that end, SST- and CORT-knockout (KO) mice and their respective littermate-controls, fed low-fat (LF) or high-fat (HF) diets, were treated with 7,12-dimethyl-benza-anthracene (DMBA) once a week (wk) for 3 wk, and MGT was monitored for 25 wk. Additionally, we examined the effect of SST or CORT removal in the development of the mammary gland. RESULTS: Lack of SST did not alter DMBA-induced MGT incidence under lean conditions; conversely, lack of endogenous CORT severely aggravated DMBA-induced MGT in LF-fed mice. These differences were not attributable to altered mammary gland development. HF-diet modestly increased the sensitivity to DMBA-induced carcinogenesis in control mice, whereas, as observed in LF-fed CORT-KO, HF-fed CORT-KO mice exhibited aggravated tumor incidence, discarding a major influence of obesity on these CORT actions. In marked contrast, HF-fed SST-KO mice exhibited much higher tumor incidence than LF-fed SST-KO mice, which could be associated with higher mammary complexity. CONCLUSIONS: Endogenous SST and CORT distinctly impact on DMBA-induced MGT, in a manner that is strongly dependent on the metabolic/endocrine milieu (lean vs. obese status). Importantly, CORT, rather than SST, could represent a major inhibitor of MGT under normal/lean-conditions, whereas both neuropeptides would similarly influence MGT under obesity conditions. The mechanisms mediating these different effects likely involve mammary development and hormones, but the precise underlying factors are still to be fully elucidated. However, our findings comprise suggestive evidence that CORT-like molecules, rather than classic SST-analogs, may help to identify novel tools for the medical treatment of breast cancer.

Morphofunctional and Molecular Assessment of Nutritional Status in Head and Neck Cancer Patients Undergoing Systemic Treatment: Role of Inflammasome in Clinical Nutrition.

Malnutrition in patients with head and neck cancer is frequent, multifactorial and widely associated with clinical evolution and prognosis. Accurate nutritional assessments allow for early identification of patients at risk of malnutrition in order to start nutritional support and prevent sarcopenia. We aimed to perform a novel morphofunctional nutritional evaluation and explore changes in inflammasome-machinery components in 45 patients with head and neck cancer who are undergoing systemic treatment. To this aim, an epidemiological/clinical/anthropometric/biochemical evaluation was performed. Serum RCP, IL6 and molecular expression of inflammasome-components and inflammatory-associated factors (NOD-like-receptors, inflammasome-activation-components, cytokines and inflammation/apoptosis-related components, cell-cycle and DNA-damage regulators) were evaluated in peripheral-blood mononuclear-cells (PBMCs). Clinical-molecular correlations/associations were analyzed. Coherent and complementary information was obtained in the morphofunctional nutritional assessment of the patients when bioimpedance, anthropometric and ultrasound data were analyzed. These factors were also correlated with different biochemical and molecular parameters, revealing the complementary aspect of the whole evaluation. Serum reactive C protein (RCP) and IL6 were the most reliable parameters for determining patients with decreased standardized phase angle, which is associated with increased mortality in patients with solid malignancies. Several inflammasome-components were dysregulated in patients with malnutrition, decreased phase angle and dependency grade or increased circulating inflammation markers. A molecular fingerprint based on gene-expression of certain inflammasome factors (p27/CCL2/ASC) in PBMCs accurately differentiated patients with and without malnutrition. In conclusion, malnutrition induces a profound alteration in the gene-expression pattern of inflammasome-machinery components in PBMCs. A comprehensive nutritional assessment including novel morphofunctional techniques and molecular markers allows a broad characterization of the nutritional status in cancer patients. Profile of certain inflammasome-components should be further studied as potential targets for nutrition-focused treatment strategies in cancer patients.

Splicing factor SF3B1 is overexpressed and implicated in the aggressiveness and survival of hepatocellular carcinoma.

Splicing alterations represent an actionable cancer hallmark. Splicing factor 3B subunit 1 (SF3B1) is a crucial splicing factor that can be targeted pharmacologically (e.g. pladienolide-B). Here, we show that SF3B1 is overexpressed (RNA/protein) in hepatocellular carcinoma (HCC) in two retrospective (n = 154 and n = 172 samples) and in five in silico cohorts (n > 900 samples, including TCGA) and that its expression is associated with tumor aggressiveness, oncogenic splicing variants expression (KLF6-SV1, BCL-XL) and decreased overall survival. In vitro, SF3B1 silencing reduced cell viability, proliferation and migration and its pharmacological blockade with pladienolide-B inhibited proliferation, migration, and formation of tumorspheres and colonies in liver cancer cell lines (HepG2, Hep3B, SNU-387), whereas its effects on normal-like hepatocyte-derived THLE-2 proliferation were negligible. Pladienolide-B also reduced the in vivo growth and the expression of tumor-markers in Hep3B-induced xenograft tumors. Moreover, SF3B1 silencing and/or blockade markedly modulated the activation of key signaling pathways (PDK1, GSK3b, ERK, JNK, AMPK) and the expression of cancer-associated genes (CDK4, CD24) and oncogenic SVs (KLF6-SV1). Therefore, the genetic and/or pharmacological inhibition of SF3B1 may represent a promising novel therapeutic strategy worth to be explored through randomized controlled trials.

Type 2 Diabetes in Neuroendocrine Tumors: Are Biguanides and Statins Part of the Solution?

Context: Biguanides and statins exert beneficial effects on various cancer types. Their precise effects and underlying molecular mechanisms are poorly understood. Materials and Methods: We analyzed the relationship between metabolic syndrome and histological, epidemiological, and prognosis variables in two cohorts of patients with neuroendocrine tumors (NETs): those with lung carcinoids (LCs; n = 81) and those with gastroenteropancreatic NET (GEP-NET; n = 100). Biguanide and statin antitumor effects were investigated by evaluating proliferation, migration, secretion, gene expression, and involved molecular pathways in BON1/QGP1 cell cultures. Results: Pleura invasion was higher (LCs group; P < 0.05) and tumor diameter tended to be increased (GEP-NET group) in patients with type 2 diabetes (T2DM) than in those without. Somatostatin and ghrelin systems mRNA levels differed in tumor tissue of patients with T2DM taking metformin or not. Biguanides decreased proliferation rate in BON1/QGP1 cells; the effects of statins on proliferation rate depended on the statin and cell types, and time. Specifically, only simvastatin and atorvastatin decreased proliferation in BON1 cells, whereas all statins decreased proliferation rate in QGP1 cells. Metformin and simvastatin decreased migration capacity in BON1 cells; biguanides decreased serotonin secretion in BON1 cells. Phenformin increased apoptosis in BON1/QGP1 cells; simvastatin increased apoptosis in QGP1 cells. These antitumor effects likely involved altered expression of key genes related to cancer aggressiveness. Conclusion: A clear inhibitory effect of biguanides and statins was seen on NET-cell aggressiveness. Our results invite additional exploration of the potential therapeutic role of these drugs in treatment of patients with NETs.

Clinical Utility of Ghrelin-O-Acyltransferase (GOAT) Enzyme as a Diagnostic Tool and Potential Therapeutic Target in Prostate Cancer.

Recent data suggested that plasma Ghrelin O-Acyl Transferase enzyme (GOAT) levels could represent a new diagnostic biomarker for prostate cancer (PCa). In this study, we aimed to explore the diagnostic and prognostic/aggressiveness capacity of GOAT in urine, as well as to interrogate its putative pathophysiological role in PCa. We analysed urine/plasma levels of GOAT in a cohort of 993 patients. In vitro (i.e., cell-proliferation) and in vivo (tumor-growth in a xenograft-model) approaches were performed in response to the modulation of GOAT expression/activity in PCa cells. Our results demonstrate that plasma and urine GOAT levels were significantly elevated in PCa patients compared to controls. Remarkably, GOAT significantly outperformed PSA in the diagnosis of PCa and significant PCa in patients with PSA levels ranging from 3 to 10 ng/mL (the so-called PSA grey-zone). Additionally, urine GOAT levels were associated to clinical (e.g., Gleason-score, PSA levels) and molecular (e.g., CDK2/CDK6/CDKN2A expression) aggressiveness parameters. Indeed, GOAT overexpression increased, while its silencing/blockade decreased cell-proliferation in PCa cells. Moreover, xenograft tumors derived from GOAT-overexpressing PCa (DU145) cells were significantly higher than those derived from the mock-overexpressing cells. Altogether, our results demonstrate that GOAT could be used as a diagnostic and aggressiveness marker in urine and a therapeutic target in PCa.

Biguanides Exert Antitumoral Actions in Pituitary Tumor Cells Through AMPK-Dependent and -Independent Mechanisms.

CONTEXT: Pituitary neuroendocrine tumors (PitNETs) are a commonly underestimated pathology in terms of incidence and associated morbimortality. Currently, an appreciable subset of patients are resistant or poorly responsive to the main current medical treatments [i.e., synthetic somatostatin analogs (SSAs) and dopamine agonists]. Thus, development and optimization of novel and available medical therapies is necessary. Biguanides (metformin, buformin, and phenformin) are antidiabetic drugs that exert antitumoral actions in several tumor types, but their pharmacological effects on PitNETs are poorly known. OBJECTIVE: We aimed to explore the direct effects of biguanides on key functions (cell viability, hormone release, apoptosis, and signaling pathways) in primary cell cultures from human PitNETs and cell lines. Additionally, we evaluated the effect of combined metformin with SSAs on cell viability and hormone secretion. DESIGN: A total of 13 corticotropinomas, 13 somatotropinomas, 13 nonfunctioning PitNETs, 3 prolactinomas, and 2 tumoral pituitary cell lines (AtT-20 and GH3) were used to evaluate the direct effects of biguanides on cell viability, hormone release, apoptosis, and signaling pathways. RESULTS: Biguanides reduced cell viability in all PitNETs and cell lines (with phenformin being the most effective biguanide) and increased apoptosis in somatotropinomas. Moreover, buformin and phenformin, but not metformin, reduced hormone secretion in a cell type-specific manner. Combination metformin/SSA therapy did not increase SSA monotherapy effectiveness. Effects of biguanides on PitNETs could involve the modulation of AMP-activated protein kinase-dependent ([Ca2+]i, PI3K/Akt) and independent (MAPK) mechanisms. CONCLUSION: Altogether, our data unveil clear antitumoral effects of biguanides on PitNET cells, opening avenues to explore their potential as drugs to treat these pathologies.

Adipokines and Their Receptors Are Widely Expressed and Distinctly Regulated by the Metabolic Environment in the Prostate of Male Mice: Direct Role Under Normal and Tumoral Conditions.

Adipose tissue-derived adipokines (i.e., leptin/adiponectin/resistin) play important roles in the regulation of several pathophysiologic processes through the activation of specific receptors. However, although adipokines and their receptors are widely distributed in many tissues and exhibit a clear modulation according to particular metabolic conditions (e.g., obesity and/or fasting), their expression, regulation, and putative action on normal prostate glands (PGs; a hormone-dependent organ tightly regulated by the endocrine-metabolic milieu) are still to be defined. Different in vivo/in vitro models were used to comprehensively characterize the expression pattern and actions of different adipokine systems (i.e., leptin/adiponectin/resistin/receptors) in mouse PGs. Adiponectin, resistin, and adiponectin receptors (1 and 2) and leptin receptor are coexpressed at different levels in PG cells, wherein they are finely regulated under fasting and/or obesity conditions. Furthermore, treatment with different adipokines exerted both homologous and heterologous regulation of specific adipokines/receptor-synthesis and altered the expression of key proliferation and oncogenesis markers (i.e., Ki67/c-Myc/p53) in mouse PG cell cultures, wherein some of these actions might be elicited through extracellular signal-regulated kinase (ERK) activation. Moreover, treatment with leptin, adiponectin, and resistin differentially regulated key functional parameters [i.e., proliferation and migration capacity and/or prostate-specific antigen (PSA) secretion] in human normal and/or tumoral prostate cell lines. Altogether, our data show that various adipokine and receptor systems are differentially expressed in normal PG cells; that their expression is under a complex ligand- and receptor-selective regulation under extreme metabolic conditions; and that they mediate distinctive and common direct actions in normal and tumoral PG cells (i.e., homologous and heterologous regulation of ligand and receptor synthesis, ERK signaling activation, modulation of proliferation markers, proliferation and migration capacity, and PSA secretion), suggesting a relevant role of these systems in the regulation of PG pathophysiology.

Metformin Reduces Prostate Tumor Growth, in a Diet-Dependent Manner, by Modulating Multiple Signaling Pathways.

Prostate-cancer is strongly influenced by obesity, wherein metformin could represent a promising treatment; however, the endocrine metabolic/cellular/molecular mechanisms underlying these associations and effects are still unclear. To determine the beneficial antitumoral effects of metformin on prostate cancer progression/aggressiveness and the relative contribution of high-fat diet (HFD; independently of obesity), we used HFD-fed immunosuppressed mice inoculated with PC3 cells (which exhibited partial resistance to diet-induced obesity) compared with low-fat diet (LFD)-fed control mice. Moreover, gene expression analysis was performed on cancer-associated genes in the xenografted tumors, and the antitumorigenic role of metformin on tumoral (PC3/22Rv1/LNCaP) and normal (RWPE1) prostate cells was evaluated. The results demonstrate that HFD is associated with enhanced prostate cancer growth irrespective of body weight gain and endocrine metabolic dysregulations and that metformin can reduce prostate cancer growth under LFD but more prominently under HFD, acting through the modulation of several tumoral-associated processes (e.g., cell cycle, apoptosis, and/or necrosis). Moreover, the actions observed in vivo could be mediated by the modulation of the local expression of GH/IGF1 axis components. Finally, it was demonstrated that metformin had disparate effects on proliferation, migration, and prostate-specific antigen secretion from different cell lines. Altogether, these data reveal that metformin inhibits prostate cancer growth under LFD and, specially, under HFD conditions through multiple metabolic/tumoral signaling pathways.Implications: The current study linking dietary influence on metformin-regulated signaling pathways and antitumoral response provides new and critical insight on environment-host interactions in cancer and therapy. Mol Cancer Res; 15(7); 862-74. ©2017 AACR.

Ghrelin O-acyltransferase (GOAT) enzyme is overexpressed in prostate cancer, and its levels are associated with patient's metabolic status: Potential value as a non-invasive biomarker.

Ghrelin-O-acyltransferase (GOAT) is the key enzyme regulating ghrelin activity, and has been proposed as a potential therapeutic target for obesity/diabetes and as a biomarker in some endocrine-related cancers. However, GOAT presence and putative role in prostate-cancer (PCa) is largely unknown. Here, we demonstrate, for the first time, that GOAT is overexpressed (mRNA/protein-level) in prostatic tissues (n = 52) and plasma/urine-samples (n = 85) of PCa-patients, compared with matched controls [healthy prostate tissues (n = 12) and plasma/urine-samples from BMI-matched controls (n = 28), respectively]. Interestingly, GOAT levels in PCa-patients correlated with aggressiveness and metabolic conditions (i.e. diabetes). Actually, GOAT expression was regulated by metabolic inputs (i.e. In1-ghrelin, insulin/IGF-I) in cultured normal prostate cells and PCa-cell lines. Importantly, ROC-curve analysis unveiled a valuable diagnostic potential for GOAT to discriminate PCa at the tissue/plasma/urine-level with high sensitivity/specificity, particularly in non-diabetic individuals. Moreover, we discovered that GOAT is secreted by PCa-cells, and that its levels are higher in urine samples from a stimulated post-massage vs. pre-massage prostate-test. In conclusion, plasmatic GOAT levels exhibit high specificity/sensitivity to predict PCa-presence compared with other PCa-biomarkers, especially in non-diabetic individuals, suggesting that GOAT holds potential as a novel non-invasive PCa-biomarker.