Vitamin D's Effect on the Proliferation and Inflammation of Human Intervertebral Disc Cells in Relation to the Functional Vitamin D Receptor Gene FokI Polymorphism

Vitamin D is known to have immunomodulatory effects, is involved in osteo-cartilaginous metabolism, and may have a role in human intervertebral disc pathophysiology. Although a link between vitamin D receptor (VDR) gene variants and disc degeneration-related pathologies has been observed, its functional contribution to pathologic processes has not been assessed yet. The aim of this study was to investigate the response of disc cells to vitamin D in terms of the regulation of proliferation, metabolism, and inflammatory processes, with a particular focus on the FokI VDR genotype. However, although it was found that vitamin D had a pro-apoptotic effect regardless of genotype, an up-regulation of IL-1Ra and downregulation of IL-6 was found to be evident only in Ff cells. Regarding the metabolic effects, in Ff cells, vitamin D promoted an upregulation of the aggrecan in inflammatory conditions but did not have an effect on the expression of collagen-related markers. Moreover, cells bearing the Ff genotype were the most responsive to vitamin D in the upregulation of catabolic markers. In addition, in contrast to the FF genotype, vitamin D downregulated the vitamin D-dependent signaling pathway in inflamed Ff cells, counteracting the inflammation-mediated catabolic effects. In conclusion, Ff cells were found to be more responsive to the anti-inflammatory and catabolic effects of vitamin D, which is likely to be related to matrix remodeling.

Housekeeping Gene Stability in Human Mesenchymal Stem and Tendon Cells Exposed to Tenogenic Factors

The use of biochemical inducers of mesenchymal stem cell (MSC) differentiation into tenogenic lineage represents an investigated aspect of tendon disorder treatment. Bone morphogenetic protein 12 (BMP-12) is a widely studied factor, representing along with ascorbic acid (AA) and basic fibroblast growth factor (bFGF) one of the most promising stimulus in this context so far. Quantitative gene expression of specific tenogenic marker is commonly used to assess the efficacy of these supplements. Nevertheless, the reliability of these data is strongly associated with the choice of stable housekeeping genes. To date, no published studies have evaluated the stability of housekeeping genes in MSCs during tenogenic induction. Three candidate housekeeping genes (YWHAZ, RPL13A, and GAPDH) in human MSCs from bone marrow (BMSCs), adipose tissue (ASCs), and tendon cells (TCs) supplemented with BMP-12 or AA and bFGF in comparison with control untreated cells for 3 and 10 days were evaluated. GeNorm, NormFinder, and BestKeeper tools and the comparative ΔCt method were used to evaluate housekeeping gene stability and the overall ranking was determined by using by the RefFinder algorithm. In all culture conditions, YWHAZ was the most stable gene and RPL13A was the second choice. YWHAZ and RPL13A were the two most stable genes also for ASCs and BMSCs, regardless of the time point analyzed, and for TCs at 10 days of tenogenic induction. Only for TCs at 3 days of tenogenic induction were GAPDH and YWHAZ the best performers. In conclusion, our findings will be useful for the proper selection of housekeeping genes in studies involving MSCs cultured in the presence of tenogenic factors, to obtain accurate and high-quality data from quantitative gene expression analysis.

CTBP1 and metabolic syndrome induce an mRNA and miRNA expression profile critical for breast cancer progression and metastasis

Metastatic breast cancer (BrCa) is still one of the main causes of cancer death in women. Metabolic syndrome (MeS), a risk factor for BrCa, is associated to high grade tumors, increased metastasis and recurrence of this disease. C-terminal binding protein 1 (CTBP1) is a co-repressor of tumor suppressor genes that is activated by low NAD⁺/NADH ratio. Previously, we demonstrated that CTBP1 hyperactivation by MeS increased tumor growth in MDA-MB-231-derived xenografts regulating several genes and miRNAs. In this work, our aim was to elucidate the role of CTBP1 and MeS in BrCa metastasis. We found that CTBP1 protein diminished adhesion while increased migration of triple negative BrCa cells. CTBP1 and MeS modulated the expression of multiple genes (ITGB4, ITGB6, PRSS2, COL17A1 and FABP4) and miRNAs (miR-378a-3p, miR-146a-5p, let-7e-3p, miR-381-5p, miR-194-5p, miR-494-3p) involved in BrCa progression of MDA-MB-231-derived xenografts. Furthermore, we demonstrated that MeS increased lung micrometastasis and liver neoplastic disease in mice. CTBP1 hyperactivation seems to be critical for MeS effect on BrCa metastasis since CTBP1 depletion completely impaired the detection of circulating tumor cells. Our results highlight CTBP1 and MeS impact on BrCa progression positioning them as key properties to be considered for BrCa patient prognosis and management.

Implications of microRNA dysregulation in the development of prostate cancer

MicroRNAs (miRNAs) are non-coding small RNAs that target mRNA to reduce protein expression. They play fundamental roles in several diseases, including prostate cancer (PCa). A single miRNA can target hundreds of mRNAs and coordinately regulate them, which implicates them in nearly every biological pathway. Hence, miRNAs modulate proliferation, cell cycle, apoptosis, adhesion, migration, invasion and metastasis, most of them constituting crucial hallmarks of cancer. Due to these properties, miRNAs emerged as promising tools for diagnostic, prognosis and management of cancer patients. Moreover, they come out as potential targets for cancer treatment, and several efforts are being made to progress in the field of miRNA-based cancer therapy. In this review, we will summarize the recent information about miRNAs in PCa. We will recapitulate all the miRNAs involved in the androgen pathway and the biology of PCa, focusing in PCa initiation and progression. In particular, we will describe the miRNAs associated with cell proliferation, cell cycle and apoptosis in PCa, as well as invasion, adhesion and metastatic miRNAs. We will revise the recent progress made understanding the role of circulating miRNAs identified in PCa that might be useful for PCa patient stratification. Another key aspect to be discussed in this review is miRNAs’ role in PCa therapy, including the miRNAs delivery.

Abstract 5496: Intratumor estradiol increment mediated by CtBP1/CYP19A1 decreases the proliferation of androgen insensitive prostate tumor cells

The normal growth and development of the prostate requires the action of estrogens and estrogens receptors (ER) a and ß. Estrogen-related pathways are clearly important in the development and progression of hormone-dependent cancers such as prostate cancer (PCa), but the role of ERß remains controversial. The production of estrogens from androgens is mediated by the aromatase enzyme. Aberrant expression of aromatase plays a critical role in PCa development and progression. Metabolic syndrome (MeS) causes sex hormone imbalance and has been identified as a risk factor for PCa. Recently, we found that C-terminal binding protein (CtBP1), a transcriptional co-repressor of tumor suppressor genes, is a novel molecular link between MeS and PCa. We developed a MeS mice model that were inoculated with PC3 stable CtBP1 depleted or control cells. MeS mice showed hormone imbalance and high levels of intratumor estradiol. Interestingly, CtBP1 strongly repressed aromatase expression in these xenografts. The aim of this study was to understand the transcriptional regulation mechanism of aromatase mediated by CtBP1 in a MeS/PCa model. To fulfill our aim, PC3 cells were co-transfected with a CtBP1 expression plasmid and a panel of ten reporter vectors containing different lengths (27-1,004 bp) of CYP19A1 promoter, cloning upstream to the luciferase gene. CtBP1 significantly repressed the activity of all the studied promoters. By chromatin inmunoprecipitation (ChIP) and RT-qPCR we determined that CtBP1 associated to CYP19A1 promoter and repressed its transcription. To identify possible CtBP1 partners in CYP19A1 expression regulation we investigated several transcription cofactors. By ChIP, we found that p300 (histone acetyl transferase) and ERß associated to aromatase promoter in PC3 cells. Using gene reporter assays, we established that CtBP1 and p300 synergistically repressed, while ER ß activated, aromatase promoter activity. Interestingly, estradiol exposure of PC3 cells, released CtBP1 from the aromatase promoter triggering its expression. Furthermore, we found that estradiol dramatically increased the viability and the S phase percentage of the androgen sensitive LNCaP and, its derivative, C4-2 cells; dramatically reducing apoptosis. Accordingly, estradiol decreased androgen insensitive PC3 cell viability and G1 phase arrest. In summary, CtBP1 represses aromatase expression in PCa. Nevertheless, MeS increases intratumor estradiol, which releases CtBP1 from aromatase promoter activating aromatase expression, which in turn, modulates prostate tumor cell proliferation.

Citation Format: Cintia Massillo, Guillermo N. Dalton, Juliana Porretti, Georgina Scalise, Paula L. Farré, Colin Clyne, Paola De Luca, Adriana De Siervi. Intratumor estradiol increment mediated by CtBP1/CYP19A1 decreases the proliferation of androgen insensitive prostate tumor cells [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 5496. doi:10.1158/1538-7445.AM2017-5496

Abstract 1984: CtBP1 and metabolic syndrome induce breast cancer progression and lung metastasis

Breast cancer (BrCa) is one of the most important public health problems in the entire world. Metabolic syndrome (MeS) increases the incidence and aggressiveness of BrCa. C-terminal binding protein 1 (CtBP1) is a co-repressor of tumor suppressor genes that is activated by low NAD+/NADH ratio. Recently, we generated a MeS-like experimental mice model by chronically feeding animals with high fat diet (HFD) and we found that CtBP1 and MeS modulated breast carcinogenesis and tumor growth. We also showed that CtBP1 and MeS decreased BrCa cell adhesion, a crucial event in the beginning of metastasis. Considering metastasis is still the main cause of death, and around 30 % of women with BrCa diagnosed at early stages will progress to metastatic stage, it is crucial to understand the impact of non-inherited factors and the mechanism underlying this process. The aim of this work was to explore CtBP1 and MeS role in BrCa cell migration and metastasis. By wound healing assay, we found that CtBP1 increased cell migration of MDA-MB-231 and 4T1 BrCa cells. To study CtBP1 and MeS effect in tumor progression, MeS nude mice induced by chronically feeding animals with HFD; and control diet fed animals, were injected with CtBP1-depleted expression or -control MDA-MB-231 cells. Six weeks post-injection primary tumors were surgically removed. After two weeks, mice were sacrificed and the presence of metastasis in lung, liver and ascites was analyzed by histology and/or quantified by RT-qPCR using specific primers for human GAPDH. Consistently with the onset of metastasis, MeS increased the number of mice that developed neoplastic ascites (20% in MeS vs. 50% in control) with presence of tumor cells (TC) detected by RT-qPCR. In addition, histological analysis and RT-qPCR quantitation revealed that CtBP1 hyperactivation by MeS significantly increased BrCa lung metastasis. Interestingly, human Vimentin mRNA was induced in TC from ascites compared to primary TC; while it was diminished in lung, suggesting the crucial role of EMT/MET processes in metastasis. Finally, we analyzed expression of cell adhesion and EMT-related genes in primary tumor tissue by RT-qPCR. We found that CtBP1 and MeS modulated cell adhesion and EMT expression genes: Vimentin, Slug, ITGB4, ITGB6, Col17A, FABP4 and PRSS2. Altogether, these results suggest a key role for MeS and CtBP1 inducing BrCa EMT and metastasis.

Citation Format: Paula Lucía Farré, Georgina Scalise, Nicolás Guillermo Dalton, Rocío Belén Duca, Karen Daniela Graña, Cintia Massillo, Juliana Porretti, Adriana De Siervi, Paola De Luca. CtBP1 and metabolic syndrome induce breast cancer progression and lung metastasis [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 1984. doi:10.1158/1538-7445.AM2017-1984

Abstract 2838: CtBP1 expression depletion on primary tumor deregulates miRNA expression and impairs development of spontaneous metastases on a prostate cancer and metabolic syndrome model

Prostate cancer (PCa) is the second cancer in incidence in men worldwide. Approximately 20 % of cases continue with advanced or metastatic disease, and at this stage, it turns out incurable due to the lack of effective therapies. Hence, the need to identify new actionable targets is crucial. Metabolic syndrome (MeS) is a physiopathological disorder that increases PCa risk and aggressiveness. C-terminal Binding Protein (CtBP1) is a transcriptional corepressor that is activated by NADH binding. Previously our group established a MeS and PCa mice model that identified to CtBP1 as a novel link associating both diseases. Moreover, cell adhesion molecules play a significant role in cancer progression and metastasis. Thus, we found that CtBP1 diminished the capability of PCa cell lines to adhere to a collagen matrix, directly modulating expression of several cell adhesion genes, including repression of the epithelial marker CDH1 and induction of the mesenchymal marker VIM. The aim of this work was to investigate MeS/CtBP1 impact over PCa progression from in situ prostate carcinoma to metastatic disease. RNA was isolated from xenografts generated on MeS mice from CtBP1 depleted PC3 cells (PC3.shCtBP1) or control (PC3.PGIPZ); and hybridized to a miRNA expression microarray (Affymetrix GeneChip® miRNA 4.0). After data normalization and analysis we identified and validated a list of 11 miRNAs regulated by CtBP1 relevant to cell adhesion and PCa progression. To investigate CtBP1 role in spontaneous PCa metastasis, NOD SCID gamma (NSG) mice were fed with control or high fat diets during 12 weeks to induce MeS. Then PC3.shCtBP1 or PC3.PGIPZ cells were injected s.c. on MeS and control animals. Body weight and tumor size were measured 1 and 3 times a week, respectively. Thirty days after cell inoculation, tumors were around 1 cm, with no significant differences between treatments; however mice showed around 20% weight loss. Mice were sacrificed and tumors, lungs and livers were collected for RNA isolation and histopathological analysis. Using human GAPDH specific primers and RT-qPCR from lungs, we found that CtBP1 depletion led to a significant decrease of lung metastases, especially in the MeS group. In addition, Hematoxylin & Eosin stains from lung sections detected the lowest number and size of metastatic foci in the CtBP1 depleted xenografts generated in MeS animals. Gene expression comparison between primary tumors and metastases showed that epithelial markers, such as E-cadherin, were induced in xenografts and almost undetected in metastasis. Accordingly, mesenchymal markers expression, such as Vimentin, was low in xenografts and triggered on metastases. Our study uncovers for the first time the role of CtBP1 in PCa progression and its molecular targets in MeS mice.

Citation Format: Guillermo N. Dalton, Georgina Scalise, Juliana Porretti, Cintia Massillo, Paula L. Farré, Paola De Luca, Adriana De Siervi. CtBP1 expression depletion on primary tumor deregulates miRNA expression and impairs development of spontaneous metastases on a prostate cancer and metabolic syndrome model [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 2838. doi:10.1158/1538-7445.AM2017-2838

Plasma vitamin D and osteo-cartilaginous markers in Italian males affected by intervertebral disc degeneration: Focus on seasonal and pathological trend of type II collagen degradation

OBJECTIVE

To evaluate plasma vitamin D and cross-linked C-telopeptides of type I (CTx-I) and type II (CTx-II) collagen concentrations in males with lumbar intervertebral disc degeneration (IVD) compared to healthy controls. Improved knowledge might suggest to optimize the vitamin D status of IVD patients and contribute to clarify mechanisms of cartilage degradation.

METHODS

79 Italian males with lumbar IVD assessed by Magnetic Resonance Imaging (MRI) and 79 age, sex and BMI-matched healthy controls were enrolled. Plasma 25hydroxyvitamin D (25(OH)D), CTx-I and CTx-II were measured by immunoassays. Circannual seasonality, correlation between biomarkers concentrations and clinical variables were assessed.

RESULTS

Overall subjects 25(OH)D and CTx-II showed month rhythmicity with acrophase in August/September and October/November, and nadir in February/March and April/May, respectively. An inverse correlation between 25(OH)D and CTx-I, and a direct correlation between CTx-II and CTx-I were observed. IVD patients, particularly with osteochondrosis, showed higher CTx-II than healthy controls.

CONCLUSIONS

Month of sampling may affect plasma 25(OH)D and CTx-II concentrations. The correlation between CTx-I and CTx-II suggests an interplay between the osteo-cartilaginous endplate and the fibro-cartilaginous disc. The results of this study highlighted that osteochondrosis associates with increased cartilaginous catabolism. Vitamin D supplementation seems more necessary in winter for lumbar IVD patients.

CtBP1 associates metabolic syndrome and breast carcinogenesis targeting multiple miRNAs

Metabolic syndrome (MeS) has been identified as a risk factor for breast cancer. C-terminal binding protein 1 (CtBP1) is a co-repressor of tumor suppressor genes that is activated by low NAD+/NADH ratio. High fat diet (HFD) increases intracellular NADH. We investigated the effect of CtBP1 hyperactivation by HFD intake on mouse breast carcinogenesis. We generated a MeS-like disease in female mice by chronically feeding animals with HFD. MeS increased postnatal mammary gland development and generated prominent duct patterns with markedly increased CtBP1 and Cyclin D1 expression. CtBP1 induced breast cancer cells proliferation. Serum from animals with MeS enriched the stem-like/progenitor cell population from breast cancer cells. CtBP1 increased breast tumor growth in MeS mice modulating multiple genes and miRNA expression implicated in cell proliferation, progenitor cells phenotype, epithelial to mesenchymal transition, mammary development and cell communication in the xenografts. These results define a novel function for CtBP1 in breast carcinogenesis.

Abstract 1914: CtBP1 and metabolic syndrome modulate cell adhesion and target multiple miRNAs in breast cancer cells

Breast cancer is the leading cause of cancer death among women, after skin cancers. Although genetic susceptibility clearly influences cancer risk, non-inherited factors determine most of the differences in cancer risk across populations and among individuals. Metabolic syndrome (MeS) increases the incidence and aggressiveness of breast cancer. C-terminal binding protein 1 (CtBP1) is a co-repressor of tumor suppressor genes that is activated by low NAD+/NADH ratio. Previously, we found that both, CtBP1 and MeS modulated breast carcinogenesis and tumor growth using a MeS experimental mice model by chronically feeding animals with high fat diet (HFD). The most severe form of breast cancer is metastatic and at this stage the disease is often fatal. The aim of this work was to investigate CtBP1 and MeS role on cell adhesion, a key process for the establishment of metastasis. We found that CtBP1 protein diminished adhesion of MDA-MB-231 breast cancer cells. More important, serum from MeS animals diminished breast cancer cell adhesion compared to control serum. In addition nude mice fed with CD or HFD were subcutaneously injected with MDA-MB-231 breast tumor cells with CtBP1 depleted expression or control cells. We found that CtBP1 and MeS modulated expression of cell adhesion targets in the xenografts, such as Vimentin, Slug, ITGB4, Col17A1, FABP4 and PRSS2.

Interestingly, miRNA expression profile obtained by RNA from CtBP1 depleted or control xenograft tumors hybridization to GeneChip miRNA 4.0 (Affymetrix) identified 42 CtBP1 regulated miRNAs. We found 77 predicted miRNAs target genes up- and 30 genes down-regulated by this set of 42 differentially expressed miRNAs, using miRecords data base. Gene ontology (GO) analysis of all these genes revealed an enrichment of localization, metabolic processes, cellular process and biological regulation categories, among other biological functions. Examining processes within these GO functions; we found important categories overrepresented, such as cell cycle, cell communication, vesicle-mediated transport and primary metabolic process.

These results clearly show that CtBP1 and MeS diminish adhesion of breast cancer cells and suggest a key role for these components in the begining of metastasis. In addition, understanding CtBP1 and MeS regulation of miRNAs could be crucial as markers for the prevention, follow up and treatment of breast cancer.

Citation Format: Paola De Luca, Paula Lucía Farré, Nicolás Dalton, Cristian Pablo Moiola, Juliana Porretti, Cintia Massillo, Georgina Scalise, Adriana De Siervi. CtBP1 and metabolic syndrome modulate cell adhesion and target multiple miRNAs in breast cancer cells. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 1914.

Abstract 5044: CtBP1 regulates olfactory and adhesion pathways in prostate cancer and metabolic syndrome

Metabolic syndrome (MeS) is a cluster of pathophysiological disorders that comprise at least three of the following factors: abdominal obesity, elevated triglycerides, dyslipidemia, high blood pressure and impaired glucose tolerance. Several studies associated MeS with increased risk for several cancer types, including prostate cancer (PCa). C-terminal binding protein 1 (CtBP1) is a potent transcriptional co-repressor of tumor suppressor genes. This protein is activated by low NAD+/NADH ratio produced by highly energetic environment such as high fat diet (HFD) intake. Previously, we identified CtBP1 as a novel molecular link between MeS and prostate tumor growth. The aim of this work was to assess the CtBP1 related pathways in PCa and MeS. We developed a MeS in vivo model by chronically feeding male nude mice with HFD. Control diet (CD) fed animals were maintained at the same conditions. These mice were inoculated with PC3 stable CtBP1 depleted or control cells. RNA obtained from xenografts was used for Genome-wide expression profiles (Affymetrix) and Gene Set Enrichment Analysis (GSEA). These analyses yielded several important pathways regulated by CtBP1, such as “Cell Adhesion” (COL17A1, PRRS2, CDH3, ITGB4, LCN2, CDH1, GJB5, TGM2 and SPARC) and “Olfactory” (OR4C45, OR5P2, GUCA1C and CLCA2). CtBP1 significantly diminished the capability of PCa cell lines to adhere to a collagen matrix, repressing the epithelial marker CDH1 and inducing the mesenchymal marker VIM expressions. Interestingly, CtBP1 associated to ITGB4 promoter gene, strongly repressing its expression. CtBP1 depletion increased the plasma membrane of the cell attached to the substrate and the number of filopodia.

From olfactory pathway, we particularly focus on Chloride Channel Accessory 2 (CLCA2), a reported breast cancer tumor suppressor gene that function inhibiting epithelial to mesenchymal transition (EMT) and invasion processes. We found that CtBP1 regulates the transcription of CLCA2 in xenografts generated on HFD-fed mice. Using a panel of luciferase reporter plasmids with variable length of the CLCA2 promoter region, we determined that CtBP1 represses CLCA2 promoter activity in PC3 cells. Moreover, we established that CtBP1 associates to the CLCA2 proximal promoter region by chromatin immunoprecipitation (ChIP). Finally, several proteins regulate CLCA2 promoter activity independently (p53, ET2 and BRCA1) or dependently of CtBP1 (p300 and HDAC2). Altogether, these results demonstrated a new role for CtBP1 in the regulation of cellular adhesion, EMT and invasion reinforcing a potential function for this protein in cancer progression. Hence, CtBP1 pathway might help to identify new molecular candidates for better prediction of PCa progression in a subset of patients with MeS

Citation Format: Guillermo N. Dalton, Juliana Porretti, Cintia Massillo, Georgina Scalise, Paula Lucía Farré, Cristian P. Moiola, Alejandra Paez, Geraldine Gueron, Paola De Luca, Adriana De Siervi. CtBP1 regulates olfactory and adhesion pathways in prostate cancer and metabolic syndrome. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 5044.

Critical role for BRCA1 expression as a marker of chemosensitivity response and prognosis

Chemotherapy is still the leader option for cancer treatment. Nevertheless some patients develop chemotherapy resistance. One major research goal is to identify the critical genes involved in chemotherapy response to predict the best therapy option for patients. Germline mutations in the BReast Cancer susceptibility gene (BRCA1) are associated to increased risk of developing breast, ovarian and other types of cancers. However, due to harmful BRCA1 gene mutations are relatively rare in the general population, nowadays most researchers focused on BRCA1 expression downregulation and/or epigenetic inactivation in sporadic tumors as a prognosis tool for chemotherapy response in patients. Chemotherapy response can be dramatically different depending on BRCA1 expression status, tumor type and drug. Hence, the chemotherapy response could be dissimilar in breast, ovarian, uterine, prostate, esophageal, gastric and lung cancers. Additionally, differential BRCA1 expression in sporadic tumors shows different response to DNA-damaging agents, mitotic inhibitors or PARP inhibitors. In this review we will examine the response to different chemotherapy agents in several cancer types depending on BRCA1 expression status.

Low doses of CPS49 and flavopiridol combination as potential treatment for advanced prostate cancer

Prostate cancer (PCa) still ranks as the second most frequently diagnosed cancer and metastatic castration resistant prostate cancer (CRPC) is a foremost cause of men cancer death around the world. The aim of this work was to investigate the selectivity and efficacy of new drug combinations for CRPC. We combined three compounds: paclitaxel (PTX: taxane that inhibits microtubule polymerization); 2-(2,4-Difluoro-phenyl)-4,5,6,7-tetrafluoro-1H-isoindole- 1,3(2H)-dione (CPS49; redox-reactive thalidomide analog with anti-angiogenic properties) and flavopiridol (flavo: semisynthetic flavonoid that inhibits cyclin dependent kinases). We assessed CPS49-flavo or -PTX combinations cytotoxicity in a panel of PCa cell lines and PC3 xenografts. We found that CPS49 enhanced flavo or PTX cytotoxicity in human PCa cell lines while showed resistance in a non-tumor cell line. Furthermore, xenografts generated by inoculation of human prostate carcinoma PC3 cells in nu/nu mice showed that CPS49/flavo administration reduced tumor growth both after 2 weeks of co-treatment and after 1 week of pretreatment with a low dose of flavo followed by 2 weeks of co-treatment. PTX and CPS49 combination did not significantly reduce tumor growth in PC3 xenografts. Histological analysis of xenograft PC3 tumor samples from CPS49/flavo combination showed extensive areas of necrosis induced by the treatment. RT-qPCR array containing 23 genes from PC3 cells or PC3 xenografts exposed to CPS49/flavo combination showed that this treatment shut down the expression of several genes involved in adhesion, migration or invasion. In summary, the antitumor activity of CPS49 or flavopiridol was improved by the combination of these compounds and using half dose of that previously reported. Hence, CPS49-flavo combination is a promising new alternative for PCa therapy.

Abstract 1160: CtBP1 is the molecular link that associates breast cancer and metabolic syndrome

Breast cancer is still one of the most important public health problems in the entire world. Obesity and metabolic syndrome (MS) increases the incidence and aggressiveness of breast cancer. C-Terminal Binding Protein (CtBP1) is a transcriptional corepressor of tumor suppressor genes and is considered a molecular sensor of cell metabolic state due to is activated in high energy conditions (high NADH). In this work we studied the effects of the activation of CtBP1 pathway by metabolic syndrome on breast tumor development and progression. We generated a murine model of MS by chronic high fat diet (HFD) administration. By histological and whole mount methods, we found that breast tissue of animals receiving HFD presented higher levels of immature adipose tissue and an increased glandular area with more generation of lateral branches and terminal end buds of mammary ducts. Breast tissue of HFD animals also showed higher expression of the proliferation markers (cyclin D1) and epithelial markers (E-cadherin). Interestingly, HFD induced CtBP1 expression in the mammary ducts. Furthermore, the number and size of mamospheres generated with LM38-LP breast cancer cells were significantly increased when cells were incubated with serum from HFD fed mice compared to the serum of animals under control diet (CD). In addition, to investigate CtBP1 role in tumor progression we performed xenografts in nude mice fed with CD or HFD by subcutaneous injecton of breast tumor cells MDA MB 231 with depleted CtBP1 expression (shRNA CtBP1) or control cells (shRNA scramble). We found that CtBP1 depletion dramatically decreased tumor growth and KI67 expression relative to control tumors. Furthermore, xenografts developed in HFD fed mice were less differentiated compared to CD. Finally, CtBP1 diminished expression tumors showed lower mesenchymal markers expression, progenitor cells markers and markers involved in mammary development. Our studies demonstrated for the first time that gene transcription regulation by CtBP1 provides an important molecular link among MS, CtBP1 function and tumor growth. Hence, these results suggest an association to understand metabolism and breast cancer.

Citation Format: Paola De Luca, Nicolás Dalton, Cristian Pablo Moiola, Carolina Flumian, Georgina Scalise, Juliana Porretti, Cintia Massillo, Edith Kordon, Laura Todaro, Elba Vazquez, Roberto Meiss, Adriana De Siervi. CtBP1 is the molecular link that associates breast cancer and metabolic syndrome. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 1160. doi:10.1158/1538-7445.AM2015-1160

Association of HO-1 and BRCA1 Is Critical for the Maintenance of Cellular Homeostasis in Prostate Cancer

Prostate cancer is the second leading cause of cancer-related death in men worldwide. Many factors that participate in the development of prostate cancer promote imbalance in the redox state of the cell. Accumulation of reactive oxygen species causes injury to cell structures, ultimately leading to cancer development. The antioxidant enzyme heme oxygenase 1 (HMOX1/HO-1) is responsible for the maintenance of the cellular homeostasis, playing a critical role in the oxidative stress and the regulation of prostate cancer development and progression. In the present study, the transcriptional regulation of HO-1 was investigated in prostate cancer. Interestingly, the tumor suppressor BRCA1 binds to the HO-1 promoter and modulates HO-1, inducing its protein levels through both the increment of its promoter activity and the induction of its transcriptional activation. In addition, in vitro and in vivo analyses show that BRCA1 also controls HO-1-negative targets: MMP9, uPA, and Cyclin D1. HO-1 transcriptional regulation is also modulated by oxidative and genotoxic agents. Induction of DNA damage by mitoxantrone and etoposide repressed HO-1 transcription, whereas hydrogen peroxide and doxorubicin induced its expression. Xenograft studies showed that HO-1 regulation by doxorubicin also occurs in vivo. Immunofluorescence analysis revealed that BRCA1 overexpression and/or doxorubicin exposure induced the cytoplasmic retention of HO-1. Finally, the transcription factor NRF2 cooperates with BRCA1 protein to activate HO-1 promoter activity. In summary, these results show that the activation of BRCA1-NRF2/HO-1 axis defines a new mechanism for the maintenance of the cellular homeostasis in prostate cancer.

IMPLICATIONS

Oxidative and genotoxic stress converge on HO-1 transcriptional activity through the combined actions of BRCA1 and NRF2.

Calcium bioaccessibility and uptake by human intestinal like cells following in vitro digestion of casein phosphopeptide–calcium aggregates

Digestion optimizes calcium distribution within CPP vectors and improves their bioactivity.

Direct but not indirect co-culture with osteogenically differentiated human bone marrow stromal cells increases RANKL/OPG ratio in human breast cancer cells generating bone metastases

Background

Bone metastases arise in nearly 70% of patients with advanced breast cancer, but the complex metastatic process has not been completely clarified yet. RANKL/RANK/OPG pathway modifications and the crosstalk between metastatic cells and bone have been indicated as potential drivers of the process. Interactions between tumor and bone cells have been studied in vivo and in vitro, but specific effects of the direct contact between human metastatic cells and human bone cells on RANKL/RANK/OPG pathway have not been investigated.

Findings

We directly co-cultured bone metastatic human breast cancer cells (BOKL) with osteo-differentiated human mesenchymal cells (BMSCs) from 3 different donors. BMSCs and BOKL were then enzymatically separated and FACS sorted. We found a significant increase in the RANKL/OPG ratio as compared to control, which was not observed in BOKL cultured in medium conditioned by BMSCs, neither in BOKL directly cultured with fibroblasts or medium conditioned by fibroblasts. Direct co-culture with osteo-differentiated BMSCs caused BOKL aggregation while proliferation was not affected by co-culture. To more specifically associate RANKL expression to osteogenic differentiation degree of BMSCs, we determined their osteogenic markers expression and matrix calcification relative to osteoblasts and fibroblasts.

Conclusions

In conclusion, our co-culture model allowed to demonstrate for the first time that direct contact but not paracrine interactions between human metastatic breast cancer cells and bone cells has a significant effect on RANKL/OPG expression in bone metastatic cells. Furthermore, only direct contact with the bone microenvironment induced BOKL clustering without however significantly influencing their proliferation and migration.

Electronic supplementary material

The online version of this article (doi:10.1186/1476-4598-13-238) contains supplementary material, which is available to authorized users.

Prostate tumor growth is impaired by CtBP1 depletion in high-fat diet-fed mice

PURPOSE

Clinical and epidemiologic data suggest that obesity is associated with more aggressive forms of prostate cancer, poor prognosis, and increased mortality. C-terminal-binding protein 1 (CtBP1) is a transcription repressor of tumor suppressor genes and is activated by NADH binding. High calorie intake decreases intracellular NAD(+)/NADH ratio. The aim of this work was to assess the effect of high-fat diet (HFD) and CtBP1 expression modulation over prostate xenograft growth.

EXPERIMENTAL DESIGN

We developed a metabolic syndrome-like disease in vivo model by feeding male nude mice with HFD during 16 weeks. Control diet (CD)-fed animals were maintained at the same conditions. Mice were inoculated with PC3 cells stable transfected with shCtBP1 or control plasmids. Genome-wide expression profiles and Gene Set Enrichment Analysis (GSEA) were performed from PC3.shCtBP1 versus PC3.pGIPZ HFD-fed mice tumors.

RESULTS

No significant differences were observed in tumor growth on CD-fed mice; however, we found that only 60% of HFD-fed mice inoculated with CtBP1-depleted cells developed a tumor. Moreover these tumors were significantly smaller than those generated by PC3.pGIPZ control xenografts. We found 823 genes differentially expressed in shCtBP1 tumors from HFD-fed mice. GSEA from expression dataset showed that most of these genes correspond to cell adhesion, metabolic process, and cell cycle.

CONCLUSIONS

Metabolic syndrome-like diseases and CtBP1 expression cooperate to induce prostate tumor growth. Hence, targeting of CtBP1 expression might be considered for prostate cancer management and therapy in the subset of patients with metabolic syndromes.

Abstract 3697: Molecular link that associates high fat diet and prostate tumor growth

Prostate Cancer (PCa) is one of the most common invasive tumors in men. Epidemiological studies indicate that diet and overweight are important factors implicated in prostate carcinogenesis. Obesity is associated with PCa aggressiveness, poorer prognosis and increased mortality. Breast cancer susceptibility gene 1 (BRCA1) interacts with several transcriptional regulators to modulate the androgen receptor (AR) signaling in PCa cell lines. Germline mutations in this gene increase breast cancer risk and are associated with high grade PCa. Previously, it had been reported that C-terminal Binding Protein 1 (CtBP1) acts as a switch to control BRCA1 transcription in response to the metabolic status of the cells. The release of CtBP1 from BRCA1 promoter through estrogen induction and high NAD+/NADH ratio (similar to high caloric intake) increases BRCA1 transcription in breast cancer cells.

The aim of this work was to assess the effect of androgens and/or high fat diet over the BRCA1/CtBP1 axis and PCa tumor growth.

We found that BRCA1 and CtBP1 proteins associate to BRCA1 proximal promoter region in PC3 cells and suppress BRCA1 transcription. Testosterone stimulation released these factors from BRCA1 promoter increasing its transcription. To assess whether this activation is mediated by testosterone or the estrogen, synthesized from testosterone by the aromatase (CYP19A1), we investigated this mechanism in the presence of letrozol (LTZ), an aromatase inhibitor. We found that LTZ abolished BRCA1 induction by testosterone, suggesting that BRCA1 activation is mediated by estrogen in these cells.

Furthermore, we generated PC3 cell lines transfected with pcDNA3-CtBP1 (PC3-CtBP1) or shRNA-CtBP1 (PC3-shCtBP1) plasmids, to overexpress or knock down CtBP1 expression, respectively. CtBP1 induction decreased BRCA1 expression in these cells and this effect was reverted by CtBP1 depletion. In addition, PC3-CtBP1 cells showed increased clonogenic capacity and proliferation compared to PC3-shCtBP1 cells.

Moreover, we developed an in vivo model to investigate the effect of high caloric diet on PCa growth after CtBP1 modulated-expression. High fat or control diet fed male nude mice were inoculated with PC3-CtBP1 and PC3-shCtBP1 stable cells. We found that CtBP1 depleted cells growing as xenografts in high fat diet fed mice dramatically decreased prostate tumor growth. Molecular analysis of tumors by RT-qPCR showed that CtBP1 depletion correlated with high BRCA1 expression. In addition, serum from high fat fed mice significantly induced PC3-CtBP1 cell proliferation in vitro.

These results strongly suggest that the potential oncogenic role of CtBP1 is dependent on the caloric diet intake. Hence, BRCA1 regulation by CtBP1 provides an important molecular link between caloric intake and tumor suppressor expression.

Citation Format: Cristian P. Moiola, Paola De Luca, Florencia Zalazar, Javier Cotignola, Estefania Labanca, Roberto Meiss, Elba S. Vazquez, Kevin Gardner, Adriana De Siervi. Molecular link that associates high fat diet and prostate tumor growth. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 3697. doi:10.1158/1538-7445.AM2013-3697

A systemic transcriptome analysis reveals the regulation of neural stem cell maintenance by an E2F1-miRNA feedback loop

Stem cell fate decisions are controlled by a molecular network in which transcription factors and miRNAs are of key importance. To systemically investigate their impact on neural stem cell (NSC) maintenance and neuronal commitment, we performed a high-throughput mRNA and miRNA profiling and isolated functional interaction networks of involved mechanisms. Thereby, we identified an E2F1–miRNA feedback loop as important regulator of NSC fate decisions. Although E2F1 supports NSC proliferation and represses transcription of miRNAs from the miR-17∼92 and miR-106a∼363 clusters, these miRNAs are transiently up-regulated at early stages of neuronal differentiation. In these early committed cells, increased miRNAs expression levels directly repress E2F1 mRNA levels and inhibit cellular proliferation. In mice, we demonstrated that these miRNAs are expressed in the neurogenic areas and that E2F1 inhibition represses NSC proliferation. The here presented data suggest a novel interaction mechanism between E2F1 and miR-17∼92 / miR-106a∼363 miRNAs in controlling NSC proliferation and neuronal differentiation.

Dynamic coregulatory complex containing BRCA1, E2F1 and CtIP controls ATM transcription

Chromosomal instability is a key feature in cancer progression. Recently we have reported that BRCA1 regulates the transcription of several genes in prostate cancer, including ATM (ataxia telangiectasia mutated). Although it is well accepted that ATM is a pivotal mediator in genotoxic stress, it is unknown whether ATM transcription is regulated during the molecular response to DNA damage. Here we investigate ATM transcription regulation in human prostate tumor PC3 cell line. We have found that doxorubicin and mitoxantrone repress ATM transcription in PC3 cells but etoposide and methotrexate do not affect ATM expression. We have demonstrated that BRCA1 binds to ATM promoter and after doxorubicin exposure, it is released. BRCA1 overexpression increases ATM transcription and this enhancement is abolished by BRCA1 depletion. Moreover, BRCA1-BRCT domain loss impairs the ability of BRCA1 to regulate ATM promoter activity, strongly suggesting that BRCT domain is essential for ATM regulation by BRCA1. BRCA1-overexpressing PC3 cells exposed to KU55933 ATM kinase inhibitor showed significant decreased ATM promoter activity compared to untreated cells, suggesting that ATM transcriptional regulation by BRCA1 is partially mediated by the ATM kinase activity. In addition, we have demonstrated E2F1 binding to ATM promoter before and after doxorubicin exposure. E2F1 overexpression diminishes ATM transcription after doxorubicin exposure which is impaired by E2F1 dominant negative mutants. Finally, the co-regulator of transcription CtIP increases ATM transcription. CtIP increases ATM transcription. Altogether, BRCA1/E2F1/CtIP binding to ATM promoter activates ATM transcription. Doxorubicin exposure releases BRCA1 and CtIP from ATM promoter still keeping E2F1 recruited and, in turn, represses ATM expression.

Abstract 1312: ATM transcriptional regulation mediated by BRCA1/E2F1 axis controls DNA damage response in prostate cancer

Prostate cancer (PCa) is the second leading cause of cancer-related death affecting men worldwide. Chromosomal instability is a key feature in PCa progression. Using genome-wide screen for factor binding in combination with expression profiles, we previously reported BRCA1 binding to several promoters involved in cell cycle regulation and DNA damage response. We also generated a BRCA1 depleted xenograft model in order to study the role of BRCA1 role in DNA damage response in vivo. We demonstrated that BRCA1 expression status plays a central role in doxorubicin resistance in PCa. One of the BRCA1 targets that emerged from these analyses was ATM (ataxia telangiectasia mutated).Although it is well accepted that the kinase protein ATM is a pivotal mediator in genotoxic stress, it is unknown if its transcriptional regulation plays a role in the DNA damage response. Our goal was to investigate ATM transcription regulation in PCa under different genotoxic insults. Here we exposed PC3 cells to different genotoxic agents and the ATM promoter activity was determined by a luciferase reporter assay. We found that the topoisomerase II inhibitors doxorubicin and mitoxantrone repressed ATM transcription; however etoposide and methotrexate did not show significant changes. Using BRCA1-overexpressing PC3 cell lines, we found that BRCA1 increases ATM mRNA and promoter activity. Accordingly, BRCA1 depletion by shRNA abolished ATM transcription induction. Furthermore, BRCT domain loss (BRCA1ΔBRCT) impaired the ability of BRCA1 to regulate ATM promoter activity, strongly suggesting that BRCT domain is essential for ATM regulation. Xenograft tumors generated by BRCA1 depleted PC3 cells injected in nu/nu mice demonstrated that BRCA1 knock-down abolished ATM transcriptional induction. Considering ATM phosphorylates BRCA1, we investigated BRCA's ability to activate ATM promoter after inhibition of the ATM kinase activity by KU55933. BRCA1 overexpressing PC3 cells exposed to KU55933 showed significant decreased ATM promoter activity compared to control cells suggesting ATM regulation by BRCA1 is not mediated by ATM kinase activity. In addition, we performed BRCA1-ChIP-qPCR using primers spanning every 500bp along ATM promoter; we found that BRCA1 binds at 500bp upstream of the ATM transcription start site which was disrupted by doxorubicin. We identified one E2F1 putative DNA binding site at this region suggesting that BRCA1 association to ATM promoter could be E2F1 mediated. Finally, E2F1 transfection in PC3 cells significant decreased ATM transcription which was impaired by E2F1 dominant negative (E1-363). In summary, BRCA1/E2F1 complex binds and induces ATM transcription. After genotoxic stress BRCA1 protein is displaced from the ATM promoter and E2F1 downregulates ATM transcription. Thus, BRCA1/E2F1 axis controls DNA damage response in PCa through ATM transcriptional regulation.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 1312. doi:1538-7445.AM2012-1312