In vitro anti-synovial sarcoma effect of diallyl trisulfide and mRNA profiling

OBJECTIVE

Synovial sarcoma (SS) is a malignant soft tissue sarcoma and its natural history is a long, indolent clinical course followed by high rate of local recurrence and distant metastasis. Current therapies are still limited in increasing satisfactory of 5-year survival, especially for patients with recurrence and metastasis. Accordingly, finding new therapeutic drug for SS treatment is clinically urgent need. Diallyl trisulfide (DATS), a bioactive compound derived from garlic, is reported as a promising anti-cancer agent for various carcinomas. However, its effect on anti-SS remains unknown. This study investigated the anti-SS effect of DATS in human synovial sarcoma SW982 cells.

METHODS

CCK-8 assay were used to examine the cell viability. High-content Imaging System was used to examine the apoptosis, intracellular ROS and autophagy. Flow cytometry was used to detect cell cycle. qPCR and Western blot were used to examine the expression of related mRNA and protein. High-throughput RNA-sequencing and bio-information analysis were used to investigate the mRNA profiling.

RESULTS

The results showed a suppressive effect of DATS on tumor biology of SW982 cells including inducing apoptosis, triggering G2/M cell cycle arrest, elevating intracellular ROS and damaging mitochondria. Further high-throughput RNA-sequencing analysis clarified a comprehensive molecular portrait for DATS-induced transcriptional regulation. Besides, protein-protein interaction (PPI) analysis demonstrated that a network consisted of FOXM1, CCNA2, CCNB1, MYBL2, PLK1 and CDK1 might be response for DATS-induced G2/M cell cycle arrest and increased intracellular ROS. Notably, protein feature analysis revealed structure enrichment in microtubule network like kinesin motors domain, and tubulin domain. Molecular function analysis suggested that DATS-induced dysfunction of microtubule network might be the major cause for its effect on cell cycle arrest and successive apoptosis. Furthermore, 28 hub genes (including KIF2C, PLK1, CDK1, BIRC5, CCNB2, CENPF, TPX2, TOP2A and so on) were determined. Finally, pathway analysis showed that DATS-induced differentially expressed genes were mainly involved in cell cycle.

CONCLUSION

Collectively, our findings for the first time provided the DATS-induced cellular response and transcriptional profiling of SW982 cells, which proposes that suppression of DATS on SS is multi-targeted and represent a therapeutic evidence for SS.

Formalin-Fixed and Paraffin-Embedded Samples for Next Generation Sequencing: Problems and Solutions

Over the years, increasing information has been asked of the pathologist: we have moved from a purely morphological diagnosis to biomolecular and genetic studies, which have made it possible to implement the use of molecular targeted therapies, such as anti-epidermal growth factor receptor (EGFR) molecules in EGFR-mutated lung cancer, for example. Today, next generation sequencing (NGS) has changed the approach to neoplasms, to the extent that, in a short time, it has gained a place of absolute importance and diagnostic, prognostic and therapeutic utility. In this scenario, formaldehyde-fixed and paraffin-embedded (FFPE) biological tissue samples are a source of clinical and molecular information. However, problems can arise in the genetic material (DNA and RNA) for use in NGS due to fixation, and work is being devoted to possible strategies to reduce its effects. In this paper, we discuss the applications of FFPE tissue samples in the execution of NGS, we focus on the problems arising with the use of this type of material for nucleic acid extraction and, finally, we consider the most useful strategies to prevent and reduce single nucleotide polymorphisms (SNV) and other fixation artifacts.

The nature of the modification at position 37 of tRNAPhe correlates with acquired taxol resistance

Acquired drug resistance is a major obstacle in cancer therapy. Recent studies revealed that reprogramming of tRNA modifications modulates cancer survival in response to chemotherapy. However, dynamic changes in tRNA modification were not elucidated. In this study, comparative analysis of the human cancer cell lines and their taxol resistant strains based on tRNA mapping was performed by using UHPLC-MS/MS. It was observed for the first time in all three cell lines that 4-demethylwyosine (imG-14) substitutes for hydroxywybutosine (OHyW) due to tRNA-wybutosine synthesizing enzyme-2 (TYW2) downregulation and becomes the predominant modification at the 37th position of tRNAphe in the taxol-resistant strains. Further analysis indicated that the increase in imG-14 levels is caused by downregulation of TYW2. The time courses of the increase in imG-14 and downregulation of TYW2 are consistent with each other as well as consistent with the time course of the development of taxol-resistance. Knockdown of TYW2 in HeLa cells caused both an accumulation of imG-14 and reduction in taxol potency. Taken together, low expression of TYW2 enzyme promotes the cancer survival and resistance to taxol therapy, implying a novel mechanism for taxol resistance. Reduction of imG-14 deposition offers an underlying rationale to overcome taxol resistance in cancer chemotherapy.

Representative cancer-associated U2AF2 mutations alter RNA interactions and splicing

High-throughput sequencing of hematologic malignancies and other cancers has revealed recurrent mis-sense mutations of genes encoding pre-mRNA splicing factors. The essential splicing factor U2AF2 recognizes a polypyrimidine-tract splice-site signal and initiates spliceosome assembly. Here, we investigate representative, acquired U2AF2 mutations, namely N196K or G301D amino acid substitutions associated with leukemia or solid tumors, respectively. We determined crystal structures of the wild-type (WT) compared with N196K- or G301D-substituted U2AF2 proteins, each bound to a prototypical AdML polypyrimidine tract, at 1.5, 1.4, or 1.7 Å resolutions. The N196K residue appears to stabilize the open conformation of U2AF2 with an inter-RNA recognition motif hydrogen bond, in agreement with an increased apparent RNA-binding affinity of the N196K-substituted protein. The G301D residue remains in a similar position as the WT residue, where unfavorable proximity to the RNA phosphodiester could explain the decreased RNA-binding affinity of the G301D-substituted protein. We found that expression of the G301D-substituted U2AF2 protein reduces splicing of a minigene transcript carrying prototypical splice sites. We further show that expression of either N196K- or G301D-substituted U2AF2 can subtly alter splicing of representative endogenous transcripts, despite the presence of endogenous, WT U2AF2 such as would be present in cancer cells. Altogether, our results demonstrate that acquired U2AF2 mutations such as N196K and G301D are capable of dysregulating gene expression for neoplastic transformation.

Evaluation of Melanoma (SK-MEL-2) Cell Growth between Three-Dimensional (3D) and Two-Dimensional (2D) Cell Cultures with Fourier Transform Infrared (FTIR) Microspectroscopy

Fourier transform infrared (FTIR) microspectroscopy was used to evaluate the growth of human melanoma cells (SK-MEL-2) in two-dimensional (2D) versus three-dimensional (3D) spheroid culture systems. FTIR microspectroscopy, coupled with multivariate analysis, could be used to monitor the variability of spheroid morphologies prepared from different cell densities. The characteristic shift in absorbance bands of the 2D cells were different from the spectra of cells from 3D spheroids. FTIR microspectroscopy can also be used to monitor cell death similar to fluorescence cell staining in 3D spheroids. A change in the secondary structure of protein was observed in cells from the 3D spheroid versus the 2D culture system. FTIR microspectroscopy can detect specific alterations in the biological components inside the spheroid, which cannot be detected using fluorescence cell death staining. In the cells from 3D spheroids, the respective lipid, DNA, and RNA region content represent specific markers directly proportional to the spheroid size and central area of necrotic cell death, which can be confirmed using unsupervised PCA and hierarchical cluster analysis. FTIR microspectroscopy could be used as an alternative tool for spheroid cell culture discrimination, and validation of the usual biochemical technique.

A tumour mRNA-triggered nanoassembly for enhanced fluorescence imaging-guided photodynamic therapy

A multifunctional theranostic nanoplatform, which integrates diagnostic and therapeutic functions in a single nanosystem, holds great promise for guiding disease treatment and improving the corresponding therapy efficacy. We report the development of a novel g-C3N4 nanosheet-based theranostic nanoassembly for both enhanced imaging of cancer-relevant mRNA in living cells and imaging-guided on-demand photodynamic therapy (PDT) for tumors. The nanoassembly was constructed by using highly fluorescent and water-dispersible g-C3N4 nanosheets which act as nanocarriers, enabling efficient and self-tracking transfection of the DNA hairpin probes. The presence of intracellular mRNA will initiate the DNA hairpin probes, ultimately resulting in an amplified fluorescence signal via hybridization and displacement with mRNA. Moreover, enhanced fluorescence imaging-guided precise PDT for tumors in living cells was also demonstrated, allowing the selective ablation of tumors without any obvious side effects. Therefore, the developed theranostic approach can provide a promising platform for low-abundance biomarker discovery and early treatment of related diseases.

Role of non-coding RNAs and RNA modifiers in cancer therapy resistance

As the standard treatments for cancer, chemotherapy and radiotherapy have been widely applied to clinical practice worldwide. However, the resistance to cancer therapies is a major challenge in clinics and scientific research, resulting in tumor recurrence and metastasis. The mechanisms of therapy resistance are complicated and result from multiple factors. Among them, non-coding RNAs (ncRNAs), along with their modifiers, have been investigated to play key roles in regulating tumor development and mediating therapy resistance within various cancers, such as hepatocellular carcinoma, breast cancer, lung cancer, gastric cancer, etc. In this review, we attempt to elucidate the mechanisms underlying ncRNA/modifier-modulated resistance to chemotherapy and radiotherapy, providing some therapeutic potential points for future cancer treatment.

Hybrid nanovaccine for the co-delivery of the mRNA antigen and adjuvant

For efficient cancer vaccines, the antitumor function largely relies on cytotoxic T cells, whose activation can be effectively induced via antigen-encoding mRNA, making mRNA-based cancer vaccines an attractive approach for personalized cancer therapy. While the liposome-based delivery system enables the systemic delivery and transfection of mRNA, incorporating an adjuvant that is non-lipid like remains challenging, although the co-delivery of mRNA (antigen) and effective adjuvant is key to the activation of the cytotoxic T cells. This is because the presence of an adjuvant is important for dendritic cell maturation-another necessity for cytotoxic T cell activation. In the present work, we designed a poly (lactic-co-glycolic acid) (PLGA)-core/lipid-shell hybrid nanoparticle carrier for the co-delivery of mRNA and gardiquimod (adjuvant that cannot be incorporated into the lipid shell). We demonstrated in the present work that the co-delivery of mRNA and gardiquimod led to the effective antigen expression and DC maturation in vitro. The intravenous administration of the hybrid nanovaccine resulted in the enrichment of mRNA expression in the spleen and a strong immune response in vivo. The simultaneous delivery of the antigen and adjuvant both spatially and temporally via the core/shell nanoparticle carrier is found to be beneficial for tumor growth inhibition.

Identifying Cancer-Specific circRNA-RBP Binding Sites Based on Deep Learning

Circular RNAs (circRNAs) are extensively expressed in cells and tissues, and play crucial roles in human diseases and biological processes. Recent studies have reported that circRNAs could function as RNA binding protein (RBP) sponges, meanwhile RBPs can also be involved in back-splicing. The interaction with RBPs is also considered an important factor for investigating the function of circRNAs. Hence, it is necessary to understand the interaction mechanisms of circRNAs and RBPs, especially in human cancers. Here, we present a novel method based on deep learning to identify cancer-specific circRNA-RBP binding sites (CSCRSites), only using the nucleotide sequences as the input. In CSCRSites, an architecture with multiple convolution layers is utilized to detect the features of the raw circRNA sequence fragments, and further identify the binding sites through a fully connected layer with the softmax output. The experimental results show that CSCRSites outperform the conventional machine learning classifiers and some representative deep learning methods on the benchmark data. In addition, the features learnt by CSCRSites are converted to sequence motifs, some of which can match to human known RNA motifs involved in human diseases, especially cancer. Therefore, as a deep learning-based tool, CSCRSites could significantly contribute to the function analysis of cancer-associated circRNAs.

Long non-coding RNA Linc00662 promotes cell invasion and contributes to cancer stem cell-like phenotypes in lung cancer cells

Long non-coding RNAs (lncRNAs) is essential in regulation of cancer cell and cancer stem cells (CSCs) behaviour. Linc00662 is a newly identified human lung cancer related lncRNA. In this study, we aimed to explore the function of Linc00662 in human lung cancer. The expression level of Linc00662 was analysed by quantitative real-time PCR. Cell metastasis and invasive ability were detected by transwell and scratch wound healing assays. The stemness of CSCs was shown by tumorsphere formation assay and flow cytometry. The interaction between Linc00662 and Lin28 was confirmed by RNA immunoprecipitation and RNA pulldown assay. Overexpression of Linc00662 promoted the poor prognosis of lung cancer. Cell invasion, metastasis and CSCs stemness in H1299 and A549 could be influenced by Linc00662. Linc00662 had direct interaction with Lin28, and the Linc00662 function was dependent on Lin28. We demonstrate that overexpression of Linc00662 enhances lung cancer cell metastasis and CSC stemness by interacting with Lin28 in human lung cancer, which could be utilized as a potential diagnostic and therapeutic target for lung cancer patients.

CircRNA has_circ_0006427 suppresses the progression of lung adenocarcinoma by regulating miR-6783-3p/DKK1 axis and inactivating Wnt/β-catenin signaling pathway

Recently, circular RNAs (circRNAs) are identified as a novel class of noncoding RNAs playing important roles in human malignant tumors. However, the regulatory function of circRNA in lung adenocarcinoma (LUAD) is still largely unknown. Present study aimed to explore the role of circ_0006427 in LUAD progression. Firstly, the downregulation of circ_0006427 in LUAD tissues and cell lines was revealed by microarray analysis and qRT-PCR analysis. And we also confirmed the circ_0006427 as a prognostic target in LUAD patients. Functionally, overexpression of circ_0006427 effectively suppressed cell proliferation, migration and invasion. Mechanistically, circ_0006427 was found to be predominantly located in the cytoplasm of LUCA cell, and was further revealed to positively regulate DKK1 in LUAD by sponging miR-6783-3p. KEGG (Kyoto Encyclopedia of Genes and Genomes) pathway analysis and western blot analysis revealed that circ_0006427 inactivated Wnt/β-catenin signaling pathway by upregulating DKK1. At last, rescue assays proved the function of circ_0006427/miR-6783-3p/DKK1 axis in LUAD progression. In conclusion, our study revealed that circ_0006427 suppressed lung adenocarcinoma progression through regulating miR-6783-3p/DKK1 axis.

Personalized Tumor RNA Loaded Lipid-Nanoparticles Prime the Systemic and Intratumoral Milieu for Response to Cancer Immunotherapy

Translation of nanoparticles (NPs) into human clinical trials for patients with refractory cancers has lagged due to unknown biologic reactivities of novel NP designs. To overcome these limitations, simple well-characterized mRNA lipid-NPs have been developed as cancer immunotherapeutic vaccines. While the preponderance of RNA lipid-NPs encoding for tumor-associated antigens or neoepitopes have been designed to target lymphoid organs, they remain encumbered by the profound intratumoral and systemic immunosuppression that may stymie an activated T cell response. Herein, we show that systemic localization of untargeted tumor RNA (derived from whole transcriptome) encapsulated in lipid-NPs, with excess positive charge, primes the peripheral and intratumoral milieu for response to immunotherapy. In immunologically resistant tumor models, these RNA-NPs activate the preponderance of systemic and intratumoral myeloid cells (characterized by coexpression of PD-L1 and CD86). Addition of immune checkpoint inhibitors (ICIs) (to animals primed with RNA-NPs) augments peripheral/intratumoral PD-1⁺CD8⁺ cells and mediates synergistic antitumor efficacy in settings where ICIs alone do not confer therapeutic benefit. These synergistic effects are mediated by type I interferon released from plasmacytoid dendritic cells (pDCs). In translational studies, personalized mRNA-NPs were safe and active in a client-owned canine with a spontaneous malignant glioma. In summary, we demonstrate widespread immune activation from tumor loaded RNA-NPs concomitant with inducible PD-L1 expression that can be therapeutically exploited. While immunotherapy remains effective for only a subset of cancer patients, combination therapy with systemic immunomodulating RNA-NPs may broaden its therapeutic potency.

Non-covalent Metallo-Drugs: Using Shape to Target DNA and RNA Junctions and Other Nucleic Acid Structures

The most effective class of anticancer drugs in clinical use are the platins which act by binding to duplex B-DNA. Yet duplex DNA is not DNA in its active form, and many other structures are formed in cells; for example, Y-shaped fork structures are involved in DNA replication and transcription and 4-way junctions with DNA repair. In this chapter we explore how large, cationic metallo-supramolecular structures can be used to bind to these less common, yet active, nucleic acid structures.

Nucleic Acid Quadruplexes and Metallo-Drugs

Guanine-rich sequences of DNA can readily fold into tetra-stranded helical assemblies known as G-quadruplexes (G4s). It has been proposed that these structures play important biological roles in transcription, translation, replication, and telomere maintenance. Therefore, over the past 20 years they have been investigated as potential drug targets for small molecules including metal complexes. This chapter provides an overview of the different classes of metal complexes as G4-binders and discusses the application of these species as optical probes for G-quadruplexes as well as metallo-drugs.

An integrative approach to assess X-chromosome inactivation using allele-specific expression with applications to epithelial ovarian cancer

X-chromosome inactivation (XCI) epigenetically silences transcription of an X chromosome in females; patterns of XCI are thought to be aberrant in women's cancers, but are understudied due to statistical challenges. We develop a two-stage statistical framework to assess skewed XCI and evaluate gene-level patterns of XCI for an individual sample by integration of RNA sequence, copy number alteration, and genotype data. Our method relies on allele-specific expression (ASE) to directly measure XCI and does not rely on male samples or paired normal tissue for comparison. We model ASE using a two-component mixture of beta distributions, allowing estimation for a given sample of the degree of skewness (based on a composite likelihood ratio test) and the posterior probability that a given gene escapes XCI (using a Bayesian beta-binomial mixture model). To illustrate the utility of our approach, we applied these methods to data from tumors of ovarian cancer patients. Among 99 patients, 45 tumors were informative for analysis and showed evidence of XCI skewed toward a particular parental chromosome. For 397 X-linked genes, we observed tumor XCI patterns largely consistent with previously identified consensus states based on multiple normal tissue types. However, 37 genes differed in XCI state between ovarian tumors and the consensus state; 17 genes aberrantly escaped XCI in ovarian tumors (including many oncogenes), whereas 20 genes were unexpectedly inactivated in ovarian tumors (including many tumor suppressor genes). These results provide evidence of the importance of XCI in ovarian cancer and demonstrate the utility of our two-stage analysis.

Optimization of the MB49 mouse bladder cancer model for adenoviral gene therapy

Bladder cancer is regarded as a promising candidate for innovative therapies in the field of immune and gene therapy. In this paper, we present the subcutaneous, metastatic and a novel orthotopic model of murine MB49 bladder cancer in C57BL/6 mice. We further show the potential of using adenoviral vectors together with different transduction enhancers to augment in vivo gene delivery. Finally, we present candidate genes for tumour detection, therapy or targeting.

The MB49 tumour grew rapidly in mice. The subcutaneous model allowed for tumour detection within a week and the possibility to monitor growth rate on a day-by-day basis. Injection of MB49 cells intravenously into the tail vein gave rise to lung metastases within 16 days, while instillation of tumour cells into pretreated bladders led to a survival time of 20–40 days. Adenoviral vectors can be used as a vehicle for gene transfer to the bladder. By far, the most potent transduction enhancer was Clorpactin, also known as oxychlorosene. Last, we show that MB49 cells express tumour-associated antigens like bladder cancer-4, prostate stem cell antigen and six-transmembrane epithelial antigen of the prostate.

Given the possibility for efficient genetic modification of the bladder and the presence of known tumour antigens, the MB49 models can be used in innovative ways to explore immunogene therapy.

A Protective Role for Androgen Receptor in Clear Cell Renal Cell Carcinoma Based on Mining TCGA Data

Androgen receptor (AR) is expressed in normal murine and human kidneys of both genders, but its physiologic role is uncertain. Several studies showed loss of AR in renal cell carcinoma (RCC) in conjunction with increasing clinical stage and pathological grade, but others found that higher AR expression correlated with worse outcomes. Limited functional studies with renal cell lines suggested tumor-promoting activity of AR. In this study, we queried transcriptomic, proteomic, epigenetic and survival data from The Cancer Genome Atlas (TCGA) to evaluate AR expression and its association with overall survival in three subtypes of RCC (clear cell [ccRCC], papillary [pRCC], and chromophobe [chRCC]). We found that although there was no significant difference in AR mRNA expression in ccRCC of males vs. females, AR protein expression in ccRCC was significantly higher in male compared to female patients. More importantly, higher expression of AR at both transcript and protein levels was associated with improved overall survival in both genders with ccRCC, but did not predict survival of either gender with pRCC or chRCC. Genes whose transcript levels were associated with AR mRNA levels significantly overlapped between ccRCC and pRCC, but not with chRCC, suggesting a similar transcriptional program mediated by AR in ccRCC and pRCC. Ingenuity pathway analysis also identified overlapping pathways and upstream regulators enriched in AR-associated genes in ccRCC and pRCC. Hypermethylation of CpG sites located in the promoter and first exon of AR was associated with loss of AR expression and poor overall survival. Our findings support a tumor suppressor role for AR in both genders that might be exploited to decrease the incidence or progression of ccRCC.

Comprehensive Molecular Characterization of Papillary Renal-Cell Carcinoma

BACKGROUND

Papillary renal-cell carcinoma, which accounts for 15 to 20% of renal-cell carcinomas, is a heterogeneous disease that consists of various types of renal cancer, including tumors with indolent, multifocal presentation and solitary tumors with an aggressive, highly lethal phenotype. Little is known about the genetic basis of sporadic papillary renal-cell carcinoma, and no effective forms of therapy for advanced disease exist.

METHODS

We performed comprehensive molecular characterization of 161 primary papillary renal-cell carcinomas, using whole-exome sequencing, copy-number analysis, messenger RNA and microRNA sequencing, DNA-methylation analysis, and proteomic analysis.

RESULTS

Type 1 and type 2 papillary renal-cell carcinomas were shown to be different types of renal cancer characterized by specific genetic alterations, with type 2 further classified into three individual subgroups on the basis of molecular differences associated with patient survival. Type 1 tumors were associated with MET alterations, whereas type 2 tumors were characterized by CDKN2A silencing, SETD2 mutations, TFE3 fusions, and increased expression of the NRF2-antioxidant response element (ARE) pathway. A CpG island methylator phenotype (CIMP) was observed in a distinct subgroup of type 2 papillary renal-cell carcinomas that was characterized by poor survival and mutation of the gene encoding fumarate hydratase (FH).

CONCLUSIONS

Type 1 and type 2 papillary renal-cell carcinomas were shown to be clinically and biologically distinct. Alterations in the MET pathway were associated with type 1, and activation of the NRF2-ARE pathway was associated with type 2; CDKN2A loss and CIMP in type 2 conveyed a poor prognosis. Furthermore, type 2 papillary renal-cell carcinoma consisted of at least three subtypes based on molecular and phenotypic features. (Funded by the National Institutes of Health.).

[Identification of 2',3'-cGMP as an intermediate of RNA catalytic cleavage by binase and evaluation of its biological action]

Binase--Bacillus pumilus RNase--endonuclease cleaves the phosphodiester bond between the 3'-guanylic residue and the 5'-OH residue of adjacent nucleotides with the formation of corresponding intermediate 2',3'-cGMP. Subsequent hydrolysis of 2',3'-cGMP into 3'-phosphate is highly specific and occurs slowly So the question arises about the existing time of that positional isomer during RNA catalytic cleavage by binase and about 2',3'-cGMP role in antitumor activity of the enzyme: In present work by means of enzyme-linked immunosorbent assay we established that during catalytic cleavage of RNA by binase 2',3'-cGMP is preserved in reaction mixture for an hour, at the same time phosphodiesterases activation doesn't lead to the total elimination of 2',3'-cGMP. The highest amount of 2',3'-cGMP was observed under the pH 8.5, it reaches nanomolar concentration at initial RNA concentration of 100-1000 μg/mL. Exogenous 2',3'-cGMP, like its positional isomer 3',5'-cGMP, doesn't trigger an apoptosis of human lung adenocarcinoma A549 cells, which are sensitive to binase apoptogenic action. Taking into account data about binase internalization and activation of mitochondrial pores opening by 2',3'-cyclic guanosine phosphates we may consider that 2',3'-cGMP can contribute to the apoptosis initiated by binase only when 2',3'-cGMP is generated intracellularly.

SLUG is a direct transcriptional repressor of PTEN tumor suppressor

BACKGROUND

PTEN/AKT signaling plays a key role in prostate cancer development and maintenance of prostate cancer stem cells. How other oncogenes or tumor suppressors interact with this pathway remain to be elucidated. SLUG is an zinc finger transcription factor of the Snail superfamily, and it promotes cancer metastasis and determines the mammary stem cell state.

METHODS

SLUG was overexpressed in cells by retroviral vector and knockdown of SLUG and PTEN was mediated by shRNAs-expressing lentiviruses. Expression level of SLUG and PTEN was examined by Western blot, RT-PCR, and qPCR analyses. PTEN promoter activity was measured by luciferase reporter assay. ChIP assay was used to measure the binding between SLUG and the PTEN promoter in vivo.

RESULT

We showed that overexpression of SLUG decreased expression of PTEN tumor repressor in prostate cancer cell lines 22RV1 and DU145; conversely, knockdown of SLUG expression elevated PTEN expresson at both protein and RNA level in these cells. We demonstrated that SLUG overexpression inhibits PTEN promoter activity through the proximal promoter region in prostate cancer cells. By ChIP assay, we confirmed that SLUG directly binds to the PTEN promoter region covering the E-box sites. We also showed that Slug deficiency leads to an increased expression of PTEN in mouse embryo fibroblasts and prostate tissues. Importantly, we found that overexpression of SLUG increases drug resistance of DU145 prostate cancer cell line and knockdown of SLUG by shRNA sensitizes DU145 cell line to chemotherapeutic drugs. We further demonstrated that PTEN knockdown converts drug sensitivity of DU145 cells expressing SLUG shRNA to anticancer drugs.

CONCLUSION

We provide compelling evidence showing that PTEN is a direct functional target of SLUG. Our findings offer new insight in the regulation of the PTEN/AKT pathway and provide a molecular basis for potential targeted therapies of prostate cancer Prostate 75:907-916, 2015. © 2015 Wiley Periodicals, Inc.

Differential gene expression profiling of functionally and developmentally distinct human prostate epithelial populations

BACKGROUND

Human fetal prostate buds appear in the 10th gestational week as solid cords, which branch and form lumens in response to androgen 1. Previous in vivo analysis of prostate epithelia isolated from benign prostatectomy specimens indicated that Epcam⁺ CD44⁻ CD49f(Hi) basal cells possess efficient tubule initiation capability relative to other subpopulations 2. Stromal interactions and branching morphogenesis displayed by adult tubule-initiating cells (TIC) are reminiscent of fetal prostate development. In the current study, we evaluated in vivo tubule initiation by human fetal prostate cells and determined expression profiles of fetal and adult epithelial subpopulations in an effort to identify pathways used by TIC.

METHODS

Immunostaining and FACS analysis based on Epcam, CD44, and CD49f expression demonstrated the majority (99.9%) of fetal prostate epithelial cells (FC) were Epcam⁺ CD44⁻ with variable levels of CD49f expression. Fetal populations isolated via cell sorting were implanted into immunocompromised mice. Total RNA isolation from Epcam⁺ CD44⁻ CD49f(Hi) FC, adult Epcam⁺ CD44⁻ CD49f(Hi) TIC, Epcam⁺ CD44⁺ CD49f(Hi) basal cells (BC), and Epcam⁺ CD44⁻ CD49f(Lo) luminal cells (LC) was performed, followed by microarray analysis of 19 samples using the Affymetrix Gene Chip Human U133 Plus 2.0 Array. Data was analyzed using Partek Genomics Suite Version 6.4. Genes selected showed >2-fold difference in expression and P < 5.00E-2. Results were validated with RT-PCR.

RESULTS

Grafts retrieved from Epcam⁺ CD44⁻ fetal cell implants displayed tubule formation with differentiation into basal and luminal compartments, while only stromal outgrowths were recovered from Epcam- fetal cell implants. Hierarchical clustering revealed four distinct groups determined by antigenic profile (TIC, BC, LC) and developmental stage (FC). TIC and BC displayed basal gene expression profiles, while LC expressed secretory genes. FC had a unique profile with the most similarities to adult TIC. Functional, network, and canonical pathway identification using Ingenuity Pathway Analysis Version 7.6 compiled genes with the highest differential expression (TIC relative to BC or LC). Many of these genes were found to be significantly associated with prostate tumorigenesis.

CONCLUSIONS

Our results demonstrate clustering gene expression profiles of FC and adult TIC. Pathways associated with TIC are known to be deregulated in cancer, suggesting a cell-of-origin role for TIC versus re-emergence of pathways common to these cells in tumorigenesis.

Reciprocal regulation of GAS5 lncRNA levels and mTOR inhibitor action in prostate cancer cells

BACKGROUND

New therapies are required for castrate-resistant prostate cancer (CRPC), and growth-arrest specific 5 (GAS5) lncRNA, which riborepresses androgen receptor action, may offer novel opportunities in this regard. This lncRNA promotes the apoptosis of prostate cancer cells and its levels decline as prostate cancer cells acquire castrate-resistance, so that enhancing GAS5 expression may improve the effectiveness of chemotherapies. Since GAS5 is a member of the 5' terminal oligopyrimidine gene family, we have examined mTOR inhibition as a strategy to increase GAS5 expression. Furthermore, we have determined if GAS5 itself mediates the action of mTOR inhibitors, as demonstrated for other chemotherapeutic agents in prostate cancer cells.

METHODS

The effects of mTOR inhibitors on GAS5 lncRNA levels and cell growth were determined in a range of prostate cancer cell lines. Transfection of cells with GAS5 siRNAs and plasmid constructs was performed to determine the involvement of GAS5 lncRNA in mTOR inhibitor action.

RESULTS

First generation mTORC1, combined mTORC1/mTORC2 and dual PI3K/mTOR inhibitors all increased cellular GAS5 levels and inhibited culture growth in androgen-dependent (LNCaP) and androgen-sensitive (22Rv1) cell lines, but not in androgen-independent (PC-3 and DU 145) cell lines. The latter exhibited low endogenous GAS5 expression, and GAS5 silencing in LNCaP and 22Rv1 cells decreased the sensitivity to mTOR inhibitors, whereas transfection of GAS5 lncRNA sensitized PC-3 and DU 145 cells to these agents.

CONCLUSION

mTOR inhibition enhances GAS5 transcript levels in certain prostate cancer cell lines. This selectivity is likely to be related to endogenous GAS5 expression levels, since GAS5 lncRNA is itself required for mTOR inhibitor action in prostate cancer cells.

Inhibition of RSK/YB-1 signaling enhances the anti-cancer effect of enzalutamide in prostate cancer

BACKGROUND

Previously, we have shown that Y-box binding protein-1 (YB-1) regulates androgen receptor (AR) expression and contributes to castration resistance. However, the mechanism of YB-1 activation remains unknown. In this study, we aimed to elucidate the mechanism and role of YB-1 activation in relation to castration resistance as well as enzalutamide resistance, with a view to developing a novel therapeutic concept for castration-resistant prostate cancer (CRPC) treatment.

METHODS

The expression and phosphorylation levels of ribosomal S6 kinase 1 (RSK1), YB-1 and AR were examined by quantitative PCR and Western blotting using prostate cancer cells. In addition, the effects of YB-1 inhibition using specific siRNA and small molecule inhibitor SL0101 on AR expression as well as combination treatment with enzalutamide and SL0101 were examined.

RESULTS

We found that androgen deprivation, as well as treatment with the next-generation anti-androgen enzalutamide, induced RSK1 and YB-1 activation followed by AR induction, which could be reversed by YB-1 shutdown and RSK inhibitor SL0101. SL0101 and enzalutamide exerted a synergistic tumor-suppressive effect on cell proliferation in androgen-dependent prostate cancer LNCaP cells, as well as castration-resistant C4-2 cells. Furthermore, the phosphorylation levels of RSK1 and YB-1 were elevated in castration- and enzalutamide-resistant cells, compared with their parental cells.

CONCLUSIONS

Taken together, these findings indicate that RSK1/YB-1 signaling contributes to castration as well as enzalutamide resistance, and that the therapeutic targeting of RSK1/YB-1 signaling would be a promising novel therapy against prostate cancer, especially CRPC when combined with enzalutamide.

MS4A8B promotes cell proliferation in prostate cancer

BACKGROUND

Prostate cancer cells must maintain or achieve the further ability of proliferation during the progression. The molecular mechanisms, however, remain poorly understood. We identified a novel oncogene, termed membrane-spanning 4-domains, subfamily A, member 8B (MS4A8B), over-expressed in prostate cancer.

METHODS

We firstly detected MS4A8B mRNA in 13 types of paired human normal and cancer tissues by real-time polymerase chain reaction (RT-PCR). In 140 clinically localized prostate cancer samples from radical prostatectomy, immunohistochemical staining was performed to study MS4A8B and PCNA protein level as an index of proliferative activity, TUNEL staining as an index of apoptosis. As MS4A8B RNAi and cDNA transfection technologies were used, the effect of MS4A8B on cellular vitality was determined in vitro and in vivo.

RESULTS

MS4A8B mRNA was over-expressed specifically in prostate cancer. Positive ratios of MS4A8B protein expression were 1.94%, 5.92%, and 62.8% in benign, HPIN and prostate cancer, respectively. Moreover, MS4A8B was positively associated with Gleason score, the proliferation index. In vitro, MS4A8B knockdown resulted in G1 -S cell cycle arrest and descended vitality, MS4A8B over-expression with accelerated S phase entry, elevated vitality in prostate cancer cells. Moreover, it was also found that expression of MS4A8B led to changes of Cyclin D1 , Cyclin E1 and PCNA. LNCaP cells transfected with sh-MS4A8B lentivirus particles grew more slowly when subcutaneously injected into the flanks of nude mice.

CONCLUSIONS

We conclude that the expression of MS4A8B expression promotes cell proliferation and plays an important role in carcinogenesis and progression of prostate cancer.

KLF9, a transcription factor induced in flutamide-caused cell apoptosis, inhibits AKT activation and suppresses tumor growth of prostate cancer cells

BACKGROUND

Kruppel-like factors (KLFs) are involved in various biological processes; emerging studies have indicated that KLF9 plays a critical role in regulating tumorigenesis. The role of KLF9 in prostate cancer (PCa), however, has not yet been investigated.

METHODS

The expression of KLF members, AKT- and apoptosis-related proteins were analyzed by Western blot or qRT-PCR. Tet-On inducible KLF9 expression was established for the evaluation of the effects of KLF9 on cell proliferation, apoptosis, and xenograft tumor growth in nude mice. Cell cycle and apoptosis were determined by flow cytometry.

RESULTS

KLF9 was induced in a time-dependent manner in flutamide-caused apoptosis, and knockdown of KLF9 significantly decreased flutamide-induced growth inhibition and apoptosis in LNCaP cells. The levels of KLF9 were relatively lower in PCa cell lines, particularly in androgen-independent cell lines compared with those in nontumorous prostate epithelial cell lines. Overexpression of KLF9 dramatically suppressed cell proliferation and caused cell cycle arrest in the G2/M phase and cell apoptosis in the androgen-independent cell lines, PC3 and DU145. Intriguingly, KLF9 expression severely suppressed the activation of AKT and its downstream targets. AKT reactivation partially rescued the KLF9-mediated inhibitory effects on the proliferation of PCa cells. More importantly, we found that KLF9 overexpression efficiently inhibited the xenograft tumor growth of PCa cells.

CONCLUSIONS

These data collectively showing that KLF9 substantially inhibits AKT activation and abrogates tumor growth of PCa cells, suggest the potential of either genetic or pharmacological activation of KLF9 in the therapeutic treatment of castration-resistant PCa.

Deregulated expression of selected histone methylases and demethylases in prostate carcinoma

Prostate cancer (PCa), a leading cause of cancer-related morbidity and mortality, arises through the acquisition of genetic and epigenetic alterations. Deregulation of histone methyltransferases (HMTs) or demethylases (HDMs) has been associated with PCa development and progression. However, the precise influence of altered HMTs or HDMs expression and respective histone marks in PCa onset and progression remains largely unknown. To clarify the role of HMTs and HDMs in prostate carcinogenesis, expression levels of 37 HMTs and 20 HDMs were assessed in normal prostate and PCa tissue samples by RT-qPCR. SMYD3, SUV39H2, PRMT6, KDM5A, and KDM6A were upregulated, whereas KMT2A-E (MLL1-5) and KDM4B were downregulated in PCa, compared with normal prostate tissues. Remarkably, PRMT6 was the histone modifier that best discriminated normal from tumorous tissue samples. Interestingly, EZH2 and SMYD3 expression levels significantly correlated with less differentiated and more aggressive tumors. Remarkably, SMYD3 expression levels were of independent prognostic value for the prediction of disease-specific survival of PCa patients with clinically localized disease submitted to radical prostatectomy. We concluded that expression profiling of HMTs and HDMs, especially SMYD3, might be of clinical usefulness for the assessment of PCa patients and assist in pre-therapeutic decision-making.

Diet-induced macrophage inhibitory cytokine 1 promotes prostate cancer progression

Recent studies have indicated that a high-fat diet (HFD) plays an important role in prostate cancer (PCa) progression. Palmitic acid (PA) is one of the most abundant saturated free fatty acids (FAs) and is associated with carcinogenesis. In this study, we investigated the mechanism underlying the association of dietary fat, including PA, with PCa progression. In four PCa cell lines, in vitro PA administration stimulated the expression of macrophage inhibitory cytokine 1 (MIC1), which is a divergent member of the transforming growth factor-β family. In vivo, LNCaP xenograft tumor growth, serum MIC1 levels, and FA levels in xenograft tumors were significantly higher in mice receiving an HFD containing high amounts of PA than in those receiving a low-fat diet (LFD). In addition, tumor cells with high MIC1 expression invaded to venules and lymph vessels in the LNCaP xenograft. In vitro studies showed that proliferation and invasive capacity were significantly higher in PCa cells cultured with serum from HFD-fed mice than in those cultured with the serum from LFD-fed mice. This effect was attenuated by the addition of neutralizing antibodies against MIC1, but not by isotype control antibodies. Clinically, serum MIC1 levels were significantly higher in PCa patients than in healthy controls, and higher levels were associated with higher pathological grade and obesity. In conclusion, our results indicate that an HFD containing PA may promote growth and invasiveness of PCa cells through the upregulation of MIC1 expression.

TBLR1 as an androgen receptor (AR) coactivator selectively activates AR target genes to inhibit prostate cancer growth

Androgen receptor (AR), a steroid hormone receptor, is critical for prostate cancer growth. However, activation of AR by androgens can also lead to growth suppression and differentiation. Transcriptional cofactors play an important role in this switch between proliferative and anti-proliferative AR target gene programs. Transducin β-like-related protein 1 (TBLR1), a core component of the nuclear receptor corepressor complex, shows both corepressor and coactivator activities on nuclear receptors, but little is known about its effects on AR and prostate cancer. We characterized TBLR1 as a coactivator of AR in prostate cancer cells and determined that the activation is dependent on both phosphorylation and 19S proteosome. We showed that TBLR1 physically interacts with AR and directly occupies the androgen-response elements of the affected AR target genes in an androgen-dependent manner. TBLR1 is primarily localized in the nucleus in benign prostate cells and nuclear expression is significantly reduced in prostate cancer cells in culture. Similarly, in human tumor samples, the expression of TBLR1 in the nucleus is significantly reduced in the malignant glands compared with the surrounding benign prostatic glands (P<0.005). Stable ectopic expression of nuclear TBLR1 leads to androgen-dependent growth suppression of prostate cancer cells in vitro and in vivo by selective activation of androgen-regulated genes associated with differentiation (e.g. KRT18) and growth suppression (e.g. NKX3-1), but not cell proliferation of the prostate cancer. Understanding the molecular switches involved in the transition from AR-dependent growth promotion to AR-dependent growth suppression will lead to more successful treatments for prostate cancer.

Transcriptome-wide analysis of UTRs in non-small cell lung cancer reveals cancer-related genes with SNV-induced changes on RNA secondary structure and miRNA target sites

Traditional mutation assessment methods generally focus on predicting disruptive changes in protein-coding regions rather than non-coding regulatory regions like untranslated regions (UTRs) of mRNAs. The UTRs, however, are known to have many sequence and structural motifs that can regulate translational and transcriptional efficiency and stability of mRNAs through interaction with RNA-binding proteins and other non-coding RNAs like microRNAs (miRNAs). In a recent study, transcriptomes of tumor cells harboring mutant and wild-type KRAS (V-Ki-ras2 Kirsten rat sarcoma viral oncogene homolog) genes in patients with non-small cell lung cancer (NSCLC) have been sequenced to identify single nucleotide variations (SNVs). About 40% of the total SNVs (73,717) identified were mapped to UTRs, but omitted in the previous analysis. To meet this obvious demand for analysis of the UTRs, we designed a comprehensive pipeline to predict the effect of SNVs on two major regulatory elements, secondary structure and miRNA target sites. Out of 29,290 SNVs in 6462 genes, we predict 472 SNVs (in 408 genes) affecting local RNA secondary structure, 490 SNVs (in 447 genes) affecting miRNA target sites and 48 that do both. Together these disruptive SNVs were present in 803 different genes, out of which 188 (23.4%) were previously known to be cancer-associated. Notably, this ratio is significantly higher (one-sided Fisher's exact test p-value = 0.032) than the ratio (20.8%) of known cancer-associated genes (n = 1347) in our initial data set (n = 6462). Network analysis shows that the genes harboring disruptive SNVs were involved in molecular mechanisms of cancer, and the signaling pathways of LPS-stimulated MAPK, IL-6, iNOS, EIF2 and mTOR. In conclusion, we have found hundreds of SNVs which are highly disruptive with respect to changes in the secondary structure and miRNA target sites within UTRs. These changes hold the potential to alter the expression of known cancer genes or genes linked to cancer-associated pathways.

Gene-expression data integration to squamous cell lung cancer subtypes reveals drug sensitivity

BACKGROUND

Squamous cell lung cancer (SqCC) is the second most common type of lung cancer in the United States. Previous studies have used gene-expression data to classify SqCC samples into four subtypes, including the primitive, classical, secretory and basal subtypes. These subtypes have different survival outcomes, although it is unknown whether these molecular subtypes predict response to therapy.

METHODS

Here, we analysed RNAseq data of 178 SqCC tumour samples and characterised the features of the different SqCC subtypes to define signature genes and pathway alterations specific to each subtype. Further, we compared the gene-expression features of each molecular subtype to specific time points in models of airway development. We also classified SqCC-derived cell lines and their reported therapeutic vulnerabilities.

RESULTS

We found that the primitive subtype may come from a later stage of differentiation, whereas the basal subtype may be from an early time. Most SqCC cell lines responded to one of five anticancer drugs (Panobinostat, 17-AAG, Irinotecan, Topotecan and Paclitaxel), whereas the basal-type cell line EBC-1 was sensitive to three other drugs (PF2341066, AZD6244 and PD-0325901).

CONCLUSION

Compared with the other three subtypes of cell lines, the secretory-type cell lines were significantly less sensitive to the five most effective drugs, possibly because of their low proliferation activity. We provide a bioinformatics framework to explore drug repurposing for cancer subtypes based on the available genomic profiles of tumour samples, normal cell types, cancer cell lines and data of drug sensitivity in cell lines.

Prostate specific membrane antigen (PSMA): a novel modulator of p38 for proliferation, migration, and survival in prostate cancer cells

BACKGROUND

Regulated activation of p38 is crucial for cell proliferation, survival, and metabolism. Our previous studies had showed that prostate specific membrane antigen (PSMA) can facilitate the proliferation, migration, survival of the LNCaP prostate cancer cell line, but the mechanisms are poorly defined.

METHODS

Our LNCaP cells had been stably transfected with lentivirus-mediated shRNA for PSMA silencing in previous study. We first testify the efficacy of PSMA knockdown in our LNCaP cell line. Then using this PSMA (-) LNCaP cell line, we compared the expression of PSMA and P-p38 by Western blotting among groups. Furthermore, we also performed immunofluorescence to confirm the change of P-p38 in cells. Then, cell viability and migration were measured by cell counting kit-8 reagent and Transwell analysis respectively. Flow cytometry was employed to evaluate cell survival.

RESULTS

After silencing the expression of PSMA, the level of the phospho-p38 (P-p38) decreased approximate 40% compared with the blank and NC groups (P < 0.05). When the cells were incubated with SB203582 (p38 inhibitor), the P-p38 in three groups was at low level and no difference among groups (P > 0.05). Then the results of immunofluorescence further proved the relationship between PSMA and P-p38. Decrease of cell viability, migration, and survival was observed upon PSMA silencing. SB203580, a specific inhibitor of p38 MAPK pathway, also reduced proliferation, migration, and survival of LNCaP cells.

CONCLUSION

These data suggests PSMA may stimulate prostate cancer cells proliferation, migration and survival through p38 MAPK pathway, revealing a novel mechanism for PSMA playing positive role on LNCaP cells.

Expression of microRNAs associated with Gleason grading system in prostate cancer: miR-182-5p is a useful marker for high grade prostate cancer

BACKGROUND

Expression profiles of some microRNAs (miRNAs) were associated with clinicopathological findings in human prostate cancer (PC), but the relative expression of miRNAs among Gleason patterns (GPs) remains unclear. In this study, we investigated the expression of several known microRNAs in each GP of PC.

METHODS

Formalin-fixed, paraffin embedded (FFPE) tissue samples were obtained from radical prostatectomy (RP) (patient set 1, n = 43, including (GP 3) n = 22, (GP 4) n = 35, and (GP 5) n = 12) and needle biopsy (patient set 2, n = 10, (GP 4) n = 10). Cancer tissues from each GP and adjacent normal counterparts were separately collected using laser-captured microdissection (LCM). Real-time RT-PCR was performed to determine the relative expression of miRNAs, including miR-31-5p, -34c-5p, -96-5p, -182-5p, -183-5p, -205-5p, -221-3p, and -222-3p, which were currently reported to be involved in PC progression.

RESULTS

In radical prostatectomy samples, relative expression of miR-31-5p, miR-34c-5p, and miR-205-5p in any GP was significantly decreased compared to normal counterpart. However, no significant difference was detected among GP 3, GP 4, and GP 5. Meanwhile, in the same GP4, expression of miR-31-5p miR-182-5p, and miR-205-5p in cancer tissues obtained from high grade cancer was significantly higher than those obtained from intermediate grade cancer. Validation study using biopsy samples revealed that the relative expression of miR-182-5p was statistically higher in high grade cancer even in same GP4.

CONCLUSIONS

We confirmed the expression of miR-182-5p depended on the cancer grade even in same GP 4. Expression of miRNA associated with Gleason grading system may contribute to more accurate preoperative cancer risk evaluation.

Expression of inflammation-mediated cluster of genes as a new marker of canine mammary malignancy

Because canine mammary tumours constitute a serious clinical problem and there are no good prognostic markers (only histopathological variables are used), the aim of the presented study was to find new malignancy markers as well as to identify intracellular pathways and biological processes characteristic for canine mammary malignancy. We compared gene expression of the most malignant mammary tumours (poorly differentiated cancers of the 3rd grade of malignancy) with less malignant tumours (well differentiated cancers of the 1st grade of malignancy). The results of our study indicated that in dogs the number of tumour-infiltrating myeloid cells or expression of myeloid-specific antigens by cancer cells is related to the cancer progression and may constitute a new marker of malignancy, however further studies in this field are required.

Role of dutasteride in pre-clinical ETS fusion-positive prostate cancer models

BACKGROUND

Androgens play a crucial role in prostate cancer, hence the androgenic pathway has become an important target of therapeutic intervention. Previously we discovered that gene fusions between the 5'-untranslated region of androgen regulated gene TMPRSS2 and the ETS transcription factor family members were present in a majority of the prostate cancer cases. The resulting aberrant overexpression of ETS genes drives tumor progression.

METHODS

Here, we evaluated the expression levels of 5α-reductase isoenzymes in prostate cancer cell lines and tissues. We tested the effect of dutasteride, a 5α-reductase inhibitor, in TMPRSS2-ERG fusion-positive VCaP cell proliferation and cell invasion. We also evaluated the effect of dutasteride on the TMPRSS2-ERG fusion gene expression. Finally, we tested dutasteride alone or in combination with an anti-androgen in VCaP cell xenografts tumor model.

RESULTS

Our data showed that 5α-reductase SRD5A1 and SRD5A3 isoenzymes that are responsible for the conversion of testosterone to DHT, are highly expressed in metastatic prostate cancer compared to benign and localized prostate cancer. Dutasteride treatment attenuated VCaP cell proliferation and invasion. VCaP cells pre-treated with dutasteride showed a reduction in ERG and PSA expression. In vivo studies demonstrated that dutasteride in combination with the anti-androgen bicalutamide significantly decreased tumor burden in VCaP cell xenograft model.

CONCLUSIONS

Our findings suggest that dutasteride can inhibit ERG fusion-positive cell growth and in combination with anti-androgen, significantly reduce the tumor burden. Our study suggests that anti-androgens used in combination with dutasteride could synergistically augment the therapeutic efficacy in the treatment of ETS-positive prostate cancer.

Epigenetic down regulation of RASSF10 and its possible clinical implication in prostate carcinoma

BACKGROUND

Ras association domain family (RASSF) comprises several tumor suppressor genes, which are often epigenetically inactivated in human tumors. Here, we aim to analyze the relevance of the recently identified member RASSF10 in prostate carcinogenesis.

METHODS

RASSF10 promoter methylation and mRNA expression were investigated by bisulfite-pyrosequencing and qRT-PCR, respectively, in prostate carcinoma (PCa) cell lines (LNCaP, 22Rv1, DU-145) and in 83 primary PCa and 53 primary benign prostatic hyperplasia (BPH) tissues obtained after radical prostatectomy. Histological localization of RASSF10 was done by in situ hybridization. To prove the epigenetic nature of RASSF10 down regulation, PCa cell lines were treated with 5-aza-2-deoxycytidine and trichostatin A. Potential function of RASSF10 was analyzed in LNCaP by colony formation and apoptosis assays.

RESULTS

RASSF10 mRNA was localized to cells of the basal layer of the prostatic gland. Absence (LNCaP) and decrease (22Rv1, DU-145) of RASSF10 expression was associated with promoter methylation and could be restored by demethylating agents. A link between RASSF10 mRNA reduction and promoter methylation was also detected in primary prostate tissues (P = 0.006), where PCa showed more frequently reduced RASSF10 levels when compared with BPH (33.7% vs. 13.2%, P = 0.009). RASSF10 methylation could be further associated with advanced tumor stage and advanced age (P-values < 0.05). Our preliminary functional assays revealed the ability of RASSF10 to inhibit colony formation (P = 0.018) and to increase apoptosis (P = 0.035).

CONCLUSIONS

This is the first study, which demonstrates the frequent epigenetic inactivation of RASSF10 in PCa and its implication in clinical symptoms of PCa.

Next generation RNA-sequencing in prognostic subsets of chronic lymphocytic leukemia

Advances in next-generation RNA-sequencing have revealed the complexity of transcriptomes by allowing both coding and noncoding(nc)RNAs to be analyzed. However, limited data exist regarding the whole transcriptional landscape of chronic lymphocytic leukemia(CLL). In this pilot-study, we evaluated RNA-sequencing in CLL by comparing two subsets which carry almost identical or "stereotyped" B-cell receptors with distinct clinical outcome, that is the poor-prognostic subset #1 (n 5 4) and the more favorable-prognostic subset #4(n 5 4). Our analysis revealed that 156 genes (e.g. LPL, WNT9A) and 76 ncRNAs, (e.g. SNORD48, SNORD115) were differentially expressed between the subsets. This technology also enabled us to identify numerous subset-specific splice variants (n 5 406), which were predominantly expressed in subset #1, including a splice-isoform of MSI2 with a novel start exon. A further important application of RNA-sequencing was for mutation detection and revealed 16–30 missense mutations per sample; notably many of these changes were found in genes with a strong potential for involvement in CLL pathogenesis, e.g., ATM and NOTCH2.This study not only demonstrates the effectiveness of RNA-sequencing for identifying mutations, quantifying gene expression and detecting splicing events, but also highlights the potential such global approaches have to significantly advance our understanding of the molecular mechanisms behind CLL development.

Oncostatin M suppresses oestrogen receptor-α expression and is associated with poor outcome in human breast cancer

The most important clinical biomarker for breast cancer management is oestrogen receptor alpha (ERα). Tumours that express ER are candidates for endocrine therapy and are biologically less aggressive, while ER-negative tumours are largely treated with conventional chemotherapy and have a poor prognosis. Despite its significance, the mechanisms regulating ER expression are poorly understood. We hypothesised that the inflammatory cytokine oncostatin M (OSM) can downregulate ER expression in breast cancer. Recombinant OSM potently suppressed ER protein and mRNA expression in vitro in a dose- and time-dependent manner in two human ER+ breast cancer cell lines, MCF7 and T47D. This was dependent on the expression of OSM receptor beta (OSMRβ) and could be blocked by inhibition of the MEKK1/2 mitogen-activated protein kinases. ER loss was also necessary for maximal OSM-induced signal transduction and migratory activity. In vivo, high expression of OSM and OSMR mRNA (determined by RT-PCR) was associated with reduced ER (P<0.01) and progesterone receptor (P<0.05) protein levels in a cohort of 70 invasive breast cancers. High OSM and OSMR mRNA expression was also associated with low expression of ESR1 (ER, P<0.0001) and ER-regulated genes in a previously published breast cancer gene expression dataset (n=321 cases). In the latter cohort, high OSMR expression was associated with shorter recurrence-free and overall survival in univariate (P<0.0001) and multivariate (P=0.022) analyses. OSM signalling may be a novel factor causing suppression of ER and disease progression in breast cancer.

Activation of the Sonic Hedgehog pathway in thyroid neoplasms and its potential role in tumor cell proliferation

The sonic hedgehog (SHH) pathway is activated in several types of malignancy and plays an important role in tumor cell proliferation and tumorigenesis. SHH binding to a 12-pass transmembrane receptor, Patched (PTCH), leads to freeing of Smoothened (SMO) and subsequent activation of GLI transcription factors. In the present study, we analyzed the expression of SHH, PTCH, SMO, and GLI1 in 31 follicular thyroid adenomas (FTA), 8 anaplastic thyroid carcinomas (ATC), and 51 papillary thyroid carcinomas (PTC) by immunohistochemical staining. More than 65% of FTA, PTC, and ATC specimens stained positive for SHH, PTCH, SMO, and GLI. However, the expression of the genes encoding these four molecules did not correlate with any clinicopathologic parameters, including the age, gender, the status of BRAF gene mutation, tumor stage, local invasion, and metastasis. Three thyroid tumor cell lines (KAT-18, WRO82, and SW1736) all expressed the genes encoding these four molecules. 5-Bromo-2-deoxyuridine labeling and MTT cell proliferation assays revealed that cyclopamine (CP), an inhibitor of the SHH pathway, was able to inhibit the proliferation of KAT-18 and WRO82 cells more effectively than SW1736 cells. CP led to the arrest of cell cycle or apoptosis. Knockdown of SHH and GLI expression by miRNA constructs that target SHH or GLI mRNA in KAT-18 and SW1736 cells led to the inhibition of cell proliferation. Our results suggest that the SHH pathway is widely activated in thyroid neoplasms and may have potential as an early marker of thyroid cancer or as a potential therapeutic target for thyroid cancer treatment.

The microRNA expression changes associated with malignancy and SDHB mutation in pheochromocytoma

Currently, the diagnosis of malignant pheochromocytoma can only be made when there is clinical evidence of metastasis or extensive local invasion. Thus, there is a need for new diagnostic marker(s) to identify tumors with malignant potential. The purpose of this study was to identify microRNAs (miRNAs) that are differentially expressed between benign and malignant pheochromocytomas and assess their diagnostic accuracy. Toward this aim, we analyzed miRNA expression in benign and malignant pheochromocytoma tumor samples using whole genome microarray profiling. Microarray analysis identified eight miRNAs that were significantly differentially expressed between benign and malignant pheochromocytomas. We measured a subset of these miRNAs directly by RT-PCR and found that miR-483-5p, miR-183, and miR-101 had significantly higher expression in malignant tumors as compared to their benign counterparts. Area under the receiver operating curve (AUC) analysis indicated that miR-483-5p, miR-101, and miR-183 could be useful diagnostic markers for distinguishing malignant from benign pheochromocytomas. In addition, these miRNAs could be detected in pheochromocytoma patient serum. Overall our data suggest that misexpression of miR-483-5p, miR-101, and miR-183 is associated with malignant pheochromocytoma.

TP53INP1 overexpression in prostate cancer correlates with poor prognostic factors and is predictive of biological cancer relapse

BACKGROUND

Tumor protein 53-induced nuclear protein 1 (TP53INP1) is a proapoptotic protein involved in cell stress response. Whereas there is an overexpression of TP53INP1 in numerous tissues submitted to stress agents, TP53INP1 is down-expressed in stomach, pancreatic, and inflammation-mediated colic carcinomas. In medullary thyroid carcinomas, TP53INP1 overexpression correlates with poor prognosis. TP53INP1 expression has never been reported in Prostate Cancer (PC). Our aim was to investigate variations of TP53INP1 expression and their correlation to clinicopathological parameters in PC.

METHODS

Quantitative measurements of immunohistochemical expression of TP53INP1 using high-throughput densitometry, assessed on digitized microscopic tissue micro-array images, were correlated with clinicopathological parameters in 91 human PC. Treatment of LNCaP tumor cells in vitro with cytokines and with TP53INP1 antisense oligonucleotide (ASO) was also analyzed.

RESULTS

In normal prostate tissues, TP53INP1 is only expressed in prostate basal cells. There is a de novo TP53INP1 expression in prostate luminal cells in inflammatory prostate tissues, high grade PIN lesions and in PC. Stimulation of LNCaP cells with inflammatory cytokines enhances the level of TP53INP1 mRNA. In PC, TP53INP1 overexpression correlates with high Gleason grade, unfavorable D'Amico score and lymph node invasion, and is an independent factor of biological cancer relapse. Moreover, treatment of LNCaP cells with a TP53INP1 ASO down-regulates TP53INP1 protein level, inhibits proliferation, and induces apoptosis.

CONCLUSION

TP53INP1 overexpression in PC seems to be a worse prognostic factor, particularly predictive of biological cancer relapse. Results in vitro suggest that TP53INP1 could be considered as a relevant target for potential specific therapy.

PC3 is a cell line characteristic of prostatic small cell carcinoma

BACKGROUND

The majority of the prostatic cancers are adenocarcinomas characterized by glandular formation and the expression of luminal differentiation markers androgen receptor (AR) and prostate-specific antigen (PSA). Most adenocarcinomas are indolent and androgen-dependent. Hormonal therapy that inhibits AR signaling produces symptomatic relief in patients with advanced and metastatic adenocarcinomas. Prostatic small cell neuroendocrine carcinoma (SCNC) is a variant form of prostate cancer (PC). In contrast to adenocarcinoma, the tumor cells of SCNC do not form glands and are negative for AR and PSA. SCNC is extremely aggressive and does not respond to hormonal therapy. The purpose of this study was to compare the important and relevant features of two most commonly used PC cell lines, LNCaP and PC3, with prostatic adenocarcinoma and SCNC.

METHODS

Xenograft tumors of LNCaP and PC3 were prepared and compared with human prostatic adenocarcinoma and SCNC for the expression of key signaling molecules by immunohistochemistry and Western blot analysis.

RESULTS

LNCaP cells express AR and PSA and their growth is inhibited by androgen withdrawal, similar to human prostatic adenocarcinoma. PC3 cells do not express AR and PSA and their proliferation is independent of androgen, similar to SCNC. Adenocarcinoma cells and LNCaP cells are negative for neuroendocrine markers and stem cell-associated marker CD44 while SCNC and PC3 cells are positive. LNCaP cells have identical cytokeratin profiles to adenocarcinoma while PC3 cells have cytokeratin profiles similar to SCNC.

CONCLUSION

LNCaP cells share common features with adenocarcinoma while PC3 cells are characteristic of SCNC.

Insulin-like growth factor-2 (IGF2) loss of imprinting marks a field defect within human prostates containing cancer

BACKGROUND

Loss of imprinting (LOI) is an epigenetic alteration involving loss of parental origin-specific expression at normally imprinted genes. A LOI for IGF2, a paracrine growth factor, has been implicated in the development of prostate and other cancers. In the current study, we define IGF2 LOI in histologically normal prostate tissues in relationship to tumor foci and gene expression.

METHODS

Microdissected tumor associated (TA) adjacent (2 mm) and distant (10 mm) tissues surrounding tumor foci were generated. IGF2 imprinting in informative prostate tissue sets was quantitated using a fluorescent primer extension assay and expression analyzed utilizing quantitative PCR. DNA methylation analyses were performed using quantitative pyrosequencing.

RESULTS

A marked IGF2 LOI was found in adjacent TA tissues (39 ± 3.1%) and did not significantly decrease in tissues distant (38 ± 5.3%) from tumor foci (45 ± 2.9%; P = 0.21). IGF2 imprinting correlated with IGF2 expression in TA tissues, but not within the tumor foci. Hypomethylation of the IGF2 DMR0 region correlated with decreased IGF2 expression in tumors (P < 0.01). The expression of IGF2 and its adjacent imprinted gene H19 were increased in adjacent and distant tissues compared to tumors (P < 0.05) indicating the importance of factors other than LOI in driving IGF2 expression.

CONCLUSIONS

LOI of IGF2 occurs not only adjacent to prostate tumor foci, but is widely prevalent even in distant areas within the peripheral zone. These data provide evidence for a widespread epigenetic field defect in histologically normal tissues that might be employed to identify prostate cancer in patients.

Knockdown of survivin (BIRC5) causes apoptosis in neuroblastoma via mitotic catastrophe

BIRC5 (survivin) is one of the genes located on chromosome arm 17q in the region that is often gained in neuroblastoma. BIRC5 is a protein in the intrinsic apoptotic pathway that interacts with XIAP and DIABLO leading to caspase-3 and caspase-9 inactivation. BIRC5 is also involved in stabilizing the microtubule-kinetochore dynamics. Based on the Affymetrix mRNA expression data, we here show that BIRC5 expression is strongly upregulated in neuroblastoma compared with normal tissues, adult malignancies, and non-malignant fetal adrenal neuroblasts. The over-expression of BIRC5 correlates with an unfavorable prognosis independent of the presence of 17q gain. Silencing of BIRC5 in neuroblastoma cell lines by various antisense molecules resulted in massive apoptosis as measured by PARP cleavage and FACS analysis. As both the intrinsic apoptotic pathway and the chromosomal passenger complex can be therapeutically targeted, we investigated in which of them BIRC5 exerted its essential anti-apoptotic role. Immunofluorescence analysis of neuroblastoma cells after BIRC5 silencing showed formation of multinucleated cells indicating mitotic catastrophe, which leads to apoptosis via P53 and CASP2. We show that BIRC5 silencing indeed resulted in activation of P53 and we could rescue apoptosis by CASP2 inhibition. We conclude that BIRC5 stabilizes the microtubules in the chromosomal passenger complex in neuroblastoma and that the apoptotic response results from mitotic catastrophe, which makes BIRC5 an interesting target for therapy.

The role of microRNA deregulation in the pathogenesis of adrenocortical carcinoma

Adrenocortical carcinoma (ACC) is an aggressive tumor showing frequent metastatic spread and poor survival. Although recent genome-wide studies of ACC have contributed to our understanding of the disease, major challenges remain for both diagnostic and prognostic assessments. The aim of this study was to identify specific microRNAs (miRNAs) associated with malignancy and survival of ACC patients. miRNA expression profiles were determined in a series of ACC, adenoma, and normal cortices using microarray. A subset of miRNAs showed distinct expression patterns in the ACC compared with adrenal cortices and adenomas. Among others, miR-483-3p, miR-483-5p, miR-210, and miR-21 were found overexpressed, while miR-195, miR-497, and miR-1974 were underexpressed in ACC. Inhibition of miR-483-3p or miR-483-5p and overexpression of miR-195 or miR-497 reduced cell proliferation in human NCI-H295R ACC cells. In addition, downregulation of miR-483-3p, but not miR-483-5p, and increased expression of miR-195 or miR-497 led to significant induction of cell death. Protein expression of p53 upregulated modulator of apoptosis (PUMA), a potential target of miR-483-3p, was significantly decreased in ACC, and inversely correlated with miR-483-3p expression. In addition, high expression of miR-503, miR-1202, and miR-1275 were found significantly associated with shorter overall survival among patients with ACC (P values: 0.006, 0.005, and 0.042 respectively). In summary, we identified additional miRNAs associated with ACC, elucidated the functional role of four miRNAs in the pathogenesis of ACC cells, demonstrated the potential involvement of the pro-apoptotic factor PUMA (a miR-483-3p target) in adrenocortical tumors, and found novel miRNAs associated with survival in ACC.

Overexpression of the natural antisense hypoxia-inducible factor-1alpha transcript is associated with malignant pheochromocytoma/paraganglioma

Paragangliomas (PGLs) have widely different metastastic potentials. Two different types of PGLs can be defined by expression profiling. Cluster 1 PGLs exhibit VHL and/or succinate dehydrogenase (SDH) mutations and a pseudohypoxic phenotype. RET and neurofibromatosis type 1 (NF1) mutations occur in cluster 2 tumors characterized by deregulation of the RAS/RAF/MAP kinase signaling cascade. Sporadic PGLs can exhibit either profile. During sustained hypoxia, a natural antisense transcript of hypoxia-inducible factor 1 (aHIF) is expressed. The role of aHIF in the metastatic potential of PGL has not yet been investigated. The aim was to test the hypothesis that genotype-specific overexpression of aHIF is associated with an increased metastatic potential. Tumor samples were collected from 87 patients with PGL. Quantitative PCR was performed for aHIF, vascular endothelial growth factor (VEGF), aquaporin 3, cytochrome b561, p57Kip2, slit homolog 3, and SDHC. Expression was related to mutation status, benign versus malignant tumors, and metastasis-free survival. We found that both aHIF and VEGF were overexpressed in cluster 1 PGLs and in metastatic tumors. In contrast, slit homolog 3, p57Kip2, cytochrome b561, and SDHC showed overexpression in non-metastatic tumors, whereas no such difference was observed for aquaporin 3. Patients with higher expression levels of aHIF and VEGF had a significantly decreased metastasis-free survival. Higher expression levels of SDHC are correlated with an increased metastasis-free survival. In conclusion, we not only demonstrate a higher expression of VEGF in cluster 1 PGL, fitting a profile of pseudohypoxia and angiogenesis, but also of aHIF. Moreover, overexpression of aHIF and VEGF marks a higher metastatic potential in PGL.

A role for class 3 semaphorins in prostate cancer

BACKGROUND

Class 3 semaphorins are secreted proteins that act as guidance cues for migrating cells via their transmembrane receptors plexins and neuropilins. Semaphorins have a role in cancer affecting tumor progression both directly, and indirectly by affecting angiogenesis.

METHODS

The expression of semaphorins and their receptors in prostate cancer cell lines and tissue was determined by RT-PCR, Western blotting and immunohistochemistry. The effect of Sema3E on prostate cancer cell lines was determined by adhesion assays and transwell migration assays.

RESULTS

Semaphorins and their receptors, plexins and neuropilins, are widely co-expressed in prostate cancer cell lines and tissue with a significant overexpression of Sema3E in tumor tissue. Sema3E affected integrin-mediated adhesion to fibronectin of prostate cancer cells, and inhibited their motility. Expression of Sema3C was upregulated and Sema3A and Sema3E were down regulated in prostate cells by hypoxia, consistent with an additional role for Sema3A and 3E as anti-angiogenic factors in prostate cancer.

CONCLUSIONS

Semaphorin 3E is aberrantly expressed in prostate cancer and affects adhesion and motility of prostate cancer cells, indicating a role for the Sema3E/PlexinD1 signaling pathway in prostate cancer and identifying a new possible target for therapy.

Androgen regulation of micro-RNAs in prostate cancer

BACKGROUND

Androgens play a critical role in the growth of both androgen dependent and castration-resistant prostate cancer (CRPC). Only a few micro-RNAs (miRNAs) have been suggested to be androgen regulated. We aim to identify androgen regulated miRNAs.

METHODS

We utilized LNCaP derived model, we have established, and which overexpresses the androgen receptor (AR), the VCaP cell line, and 13 intact-castrated prostate cancer (PC) xenograft pairs, as well as clinical specimens of untreated (PC) and CRPC. The expression of miRNAs was analyzed by microarrays and quantitative RT-PCR (Q-RT-PCR). Transfection of pre-miR-141 and anti-miR-141 was also used.

RESULTS

Seventeen miRNAs were > 1.5-fold up- or downregulated upon dihydrotestosterone (DHT) treatment in the cell lines, and 42 after castration in the AR-positive xenografts. Only four miRNAs (miR-10a, miR-141, miR-150*, and miR-1225-5p) showed similar androgen regulation in both cell lines and xenografts. Of those, miR-141 was found to be expressed more in PC and CRPC compared to benign prostate hyperplasia. Additionally, the overexpression of miR-141 enhanced growth of parental LNCaP cells while inhibition of miR-141 by anti-miR-141 suppressed the growth of the LNCaP subline overexpressing AR.

CONCLUSIONS

Only a few miRNAs were found to be androgen-regulated in both cell lines and xenografts models. Of those, the expression of miR-141 was upregulated in cancer. The ectopic overexpression of miR-141 increased growth of LNCaP cell suggesting it may contribute to the progression of PC.

LL-37 as a therapeutic target for late stage prostate cancer

BACKGROUND

The antimicrobial peptide, leucine-leucine-37 (LL-37), stimulates proliferation, angiogenesis, and cellular migration, inhibits apoptosis and is associated with inflammation. Since these functional processes are often exaggerated in cancer, the aim of the present study was to investigate the expression and role of LL-37 in prostate cancer (PCa) and establish its value as a therapeutic target.

METHODS

We evaluated the expression of LL-37 and the murine orthologue, cathelicidin-related antimicrobial peptide (CRAMP) in human and murine prostate tumors, respectively. Compared to normal/benign prostate tissue, both LL-37 and CRAMP were increasingly over-expressed with advancing grades of primary PCa and its metastasis in human tissues and in the transgenic adenocarcinoma mouse prostate (TRAMP) model, correspondingly. We subsequently knocked-down CRAMP in the highly tumorigenic TRAMP-C1 cell line via a RNA interference strategy to examine the importance of CRAMP on cellular proliferation, angiogenesis, invasion, apoptosis, activation of signaling pathways and tumor kinetics.

RESULTS

Abrogation of CRAMP expression led to decreased proliferation, invasion, type IV collagenase, and the amount of phosphorylated Erk1/2 and Akt signaling in vitro. These results were paralleled in vivo. Syngenic implantation of TRAMP-C1 cells subjected to CRAMP knock-down resulted in a decreased tumor incidence and size, and the down-regulation of pro-tumorigenic mechanisms.

CONCLUSIONS

CRAMP knock-down in a murine PCa model analogously demonstrated the tumorigenic contributions of LL-37 in PCa and its potential as a novel therapeutic target for the treatment of PCa and potentially, other cancers over-expressing the peptide.

A new method to provide a fresh frozen prostate slice suitable for gene expression study and MR spectroscopy

BACKGROUND

Fresh frozen tissue from radical prostatectomy specimens is highly valuable material for research on gene expression and cellular metabolites. The purpose of this study was to develop a standardized method to provide a representative high quality research sample from radical prostatectomy specimens without interfering with the routine histopathological procedure.

METHODS

A complete transversal slice is collected and snap-frozen before formalin fixation and routine processing of the remaining gland. The freezing preserves the original geometric shape, thus allowing subsampling of specific cell populations without thawing. RNA was extracted from 53 cylindrical subsamples (diameter 3 mm, thickness 2 mm) from 16 consecutive frozen slices. The histological pattern was evaluated by microscopy of a cryosection from sample before further analysis.

RESULTS

Using this novel harvesting method close to 400 slices have been collected. Whenever tumor was present in both adjacent surrounding hematoxylin-eosin sections, we found cancer in 88% of the frozen slices. The extracted RNA showed very high quality with a mean RNA integrity number of 9.16 (SD 0.53). The MR spectra showed metabolic profiles containing several resonances, which deserve further evaluation as possible biomarkers for prostate cancer. After MR analysis the RNA was still highly intact with a mean RNA integrity number of 8.40 (SD 1.53), which makes it possible to correlate transcriptomic and metabolomic profiles of the extracted samples.

CONCLUSION

We present a safe and standardized method for procurement of a high quality fresh frozen prostate slice, suitable for gene expression analysis and MR spectroscopy.

1,25-dihydroxyvitamin D3 and a superagonistic analog in combination with paclitaxel or suberoylanilide hydroxamic acid have potent antiproliferative effects on anaplastic thyroid cancer

Anaplastic thyroid cancer represents one of the most aggressive cancers. The active form of vitamin D, 1,25-dihydroxyvitamin D(3) (1,25(OH)(2)D(3)), has been shown to have antiproliferative and/or redifferentiating properties in several malignancies, including thyroid cancer. The objective of this study was to investigate the effects of 1,25(OH)(2)D(3) and the superagonistic analog CD578 in anaplastic thyroid cancer, alone or in combination with paclitaxel, a taxane, and suberoylanilide hydroxamic acid (SAHA), a potent histone deacetylase inhibitor with promising effects in undifferentiated thyroid cancer. Four human thyroid cancer cell lines (FTC-133, C643, 8505C and HTh74) were treated with 1,25(OH)(2)D(3) or CD578, alone or in combination with paclitaxel or SAHA. Effects on cell growth and differentiation were evaluated. Clear effects on growth arrest were observed in a clonogenic assay, and absolute cell counts demonstrated a 24-36% reduction in all cell lines after 72h treatment with 1,25(OH)(2)D(3) (10(-6)M) and a 60% inhibition after 120h in the most sensitive cell line HTh74. A similar growth inhibition was shown after treatment with a 1000-fold lower concentration of analog CD578. This growth arrest was explained by antiproliferative effects, further supported by an increased % of cells in the G(0)-G(1) phase of the cell cycle and by a decreased transcription factor E2F1 mRNA expression. Combination treatments of 1,25(OH)(2)D(3) or CD578 with paclitaxel or SAHA resulted in an additive and in some conditions a synergistic effect on the inhibition of proliferation. Redifferentiation analysis revealed only a modest increase in sodium iodide symporter and thyroglobulin mRNA expression after treatment with 1,25(OH)(2)D(3), without additive effect after combination treatment. No effects were observed on TSH-receptor or thyroid peroxidase mRNA expression. Our in vitro findings demonstrate that the superagonistic vitamin D analog CD578 holds promise as adjuvant antiproliferative therapy of anaplastic thyroid cancer, especially in combination with other drugs such as paclitaxel or SAHA.