The emergence of protocadherin-PC expression during the acquisition of apoptosis-resistance by prostate cancer cells

PCDH8 is a novel prognostic biomarker in thyroid cancer and promotes cell proliferation and viability

Protocadherin 8 (PCDH8), a calcium-dependent transmembrane protein in the protocadherin family, regulates cell adhesion and signal transduction. While some studies have provided indirect evidence that PCDH8 has cancer-promoting properties, this association is controversial. In particular, its involvement in thyroid cancer (THCA) remains unclear. We aimed to elucidate the role of PCDH8 in THCA using bioinformatic analysis. Subsequently, the results were experimentally validated. The analysis conducted using the R programming language and online web tools explored PCDH8 expression levels, prognostic, and clinical implications, and its relationship with the tumor immune microenvironment in THCA. Furthermore, we examined the association between PCDH8 and co-expressed genes, highlighting their involvement in several biological processes relevant to THCA. The potential of PCDH8 as a therapeutic target for this pathology was also explored. Immunohistochemical (IHC) staining was performed on samples from 98 patients with THCA, and experimental validation was carried out. PCDH8 was significantly elevated in cancer tissues and associated with poor prognosis, several clinical factors, and immune cell and checkpoint abundance. Cox regression and survival analyses, together with Receiver Operating Curves (ROC) indicated that PCDH8 was an independent prognostic factor for THCA. Furthermore, PCDH8 impacts cell viability and proliferation, promoting tumorigenesis. Also, it influences tumor cell sensitivity to various drugs. Thus, PCDH8 might be a potential therapeutic target for THCA. IHC, cell culture, MTT, and colony formation experiments further confirmed our findings. This analysis provided insights into the potential carcinogenic role of PCDH8 in THCA, as it impacts cell viability and proliferation. Thus, PCDH8 might play an important role in its prognosis, immune infiltration, and diagnosis.

Identification of Biomarkers Associated with Liver Metastasis Progression from Colorectal Cancer Using Exosomal RNA Profiling

This study aimed to identify novel biomarkers for metastatic colorectal cancer progression using exosomal RNA expression profiling. The exosomal RNA expression profiles of 54 patients with mCRC were investigated. Exosomal RNA profiling was performed at the time of relapse immediately before metastasectomy and cancer recurrence or progression after metastasectomy. The up- and down-regulated RNA expression profiles were screened and analyzed using H-cluster, principle component analysis and gene ontology. The tissue expression profile of the liver metastases was compared with the GSE 41258 set using GSEA tools. We identified two distinctive biological process gene sets (IFNA and PCDB families) related to metastatic progression. The interferon-α response gene set was enriched, especially when the tumor volume was ≥1 cm3. CXCL10, CXCL11 and SAMD 9 mRNA were highly expressed in the plasma exosome samples of patients with mCRC to the liver. Furthermore, high expression of CXCL10 but not CXCL11 or SAMD9 was associated with a poor prognosis and shorter progression-free survival. Conclusions: Cancer-derived exosomal CXCL10 may be a novel biomarker for liver metastasis of mCRC and a potential target for the prevention and treatment of mCRC with liver metastasis.

Protocadherins at the Crossroad of Signaling Pathways

Protocadherins (Pcdhs) are cell adhesion molecules that belong to the cadherin superfamily, and are subdivided into clustered (cPcdhs) and non-clustered Pcdhs (ncPcdhs) in vertebrates. In this review, we summarize their discovery, expression mechanisms, and roles in neuronal development and cancer, thereby highlighting the context-dependent nature of their actions. We furthermore provide an extensive overview of current structural knowledge, and its implications concerning extracellular interactions between cPcdhs, ncPcdhs, and classical cadherins. Next, we survey the known molecular action mechanisms of Pcdhs, emphasizing the regulatory functions of proteolytic processing and domain shedding. In addition, we outline the importance of Pcdh intracellular domains in the regulation of downstream signaling cascades, and we describe putative Pcdh interactions with intracellular molecules including components of the WAVE complex, the Wnt pathway, and apoptotic cascades. Our overview combines molecular interaction data from different contexts, such as neural development and cancer. This comprehensive approach reveals potential common Pcdh signaling hubs, and points out future directions for research. Functional studies of such key factors within the context of neural development might yield innovative insights into the molecular etiology of Pcdh-related neurodevelopmental disorders.

Cadherin Signaling in Cancer: Its Functions and Role as a Therapeutic Target

Cadherin family includes lists of transmembrane glycoproteins which mediate calcium-dependent cell-cell adhesion. Cadherin-mediated adhesion regulates cell growth and differentiation throughout life. Through the establishment of the cadherin-catenin complex, cadherins provide normal cell-cell adhesion and maintain homeostatic tissue architecture. In the process of cell recognition and adhesion, cadherins act as vital participators. As results, the disruption of cadherin signaling has significant implications on tumor formation and progression. Altered cadherin expression plays a vital role in tumorigenesis, tumor progression, angiogenesis, and tumor immune response. Based on ongoing research into the role of cadherin signaling in malignant tumors, cadherins are now being considered as potential targets for cancer therapies. This review will demonstrate the mechanisms of cadherin involvement in tumor progression, and consider the clinical significance of cadherins as therapeutic targets.

Protocadherin B9 promotes resistance to bicalutamide and is associated with the survival of prostate cancer patients

Background Prostate cancer (PCa) is a common malignancy worldwide and is the second leading cause of cancer death in men. The standard therapy for advanced PCa is androgen deprivation therapy (ADT). Although ADT, including bicalutamide treatment, is initially effective, resistance to bicalutamide frequently occurs and leads to the development of castration-resistant PCa. Thus, clarifying the mechanisms of bicalutamide resistance is urgently needed. We designed this study to assess the expression and function of PCDHB9, which encodes the protocadherin B9 protein. Methods The expression of PCDHB9 was determined using immunohistochemistry and a qRT-PCR. The effects of the overexpression or knockdown of PCDHB9 on cell growth, migration, adhesion were evaluated. To evaluate the PCDHB9-mediated effects in PCa, we performed a gene expression analysis using DU145 transfected with PCDHB9. We examined the effects of PCDHB9 inhibition on bicalutamide resistance. Results The qRT-PCR revealed that the expression of PCDHB9 was much higher in PCa than that in non-neoplastic prostate tissues. In 152 clinically localized PCa cases immunohistochemistry showed that 59% of PCa cases were positive for protocadherin B9. A Kaplan-Meier analysis showed that the high expression of protocadherin B9 was associated with PSA recurrence after radical prostatectomy. A functional analysis showed that PCDHB9 modulated cell migration and adhesion. We also found that PCDHB9 induced the expression of ITGB6 based on a gene expression analysis. The effect of PCDHB9 inhibition on bicalutamide sensitivity was examined using MTT assays. The IC₅₀ value of PCDHB9 siRNA-transfected PCa cells was significantly lower than that of negative control siRNA-transfected cells. Furthermore, immunohistochemical staining of protocadherin B9 in 74 PCa patients who were treated with androgen depletion therapy, including bicalutamide treatment, demonstrated that the high expression of protocadherin B9 was significantly associated with poor overall survival. Conclusions PCDHB9 plays an important role in the progression of PCa and bicalutamide resistance. Collectively, our results suggest that PCDHB9 targeted therapy may be more effective than bicalutamide alone.

Characterization of potential driver mutations involved in human breast cancer by computational approaches

Breast cancer is the second most frequently occurring form of cancer and is also the second most lethal cancer in women worldwide. A genetic mutation is one of the key factors that alter multiple cellular regulatory pathways and drive breast cancer initiation and progression yet nature of these cancer drivers remains elusive. In this article, we have reviewed various computational perspectives and algorithms for exploring breast cancer driver mutation genes. Using both frequency based and mutational exclusivity based approaches, we identified 195 driver genes and shortlisted 63 of them as candidate drivers for breast cancer using various computational approaches. Finally, we conducted network and pathway analysis to explore their functions in breast tumorigenesis including tumor initiation, progression, and metastasis.

PCDHGA9 acts as a tumor suppressor to induce tumor cell apoptosis and autophagy and inhibit the EMT process in human gastric cancer

The results of a cDNA  array revealed that protocadherin gamma subfamily A, 9 (PCDHGA9) was significantly decreased in SGC-7901 gastric cancer (GC) cells compared with GES-1 normal gastric cells and was strongly associated with the Wnt/β-catenin and transforming growth factor-β (TGF-β)/Smad2/3 signaling pathway. As a member of the cadherin family, PCDHGA9 functions in both cell-cell adhesion and nuclear signaling. However, its role in tumorigenicity or metastasis has not been reported. In the present study, we found that PCDHGA9 was decreased in GC tissues compared with corresponding normal mucosae and its expression was correlated with the GC TNM stage, the UICC stage, differentiation, relapse, and metastasis (p < 0.01). Multivariate Cox analysis revealed that PCDHGA9 was an independent prognostic indicator for overall survival (OS) and disease-free survival (DFS) (p < 0.01). The effects of PCDHGA9 on GC tumor growth and metastasis were examined both in vivo and in vitro. PCDHGA9 knockdown promoted GC cell proliferation, migration, and invasion, whereas PCDHGA9 overexpression inhibited GC tumor growth and metastasis but induced apoptosis, autophagy, and G1 cell cycle arrest. Furthermore, PCDHGA9 suppressed epithelial-mesenchymal transition (EMT) induced by TGF-β, decreased the phosphorylation of Smad2/3, and inhibited the nuclear translocation of pSmad2/3. Our results suggest that PCDHGA9 might interact with β-catenin to prevent β-catenin from dissociating in the cytoplasm and translocating to the nucleus. Moreover, PCDHGA9 overexpression restrained cell proliferation and reduced the nuclear β-catenin, an indicator of Wnt/β-catenin pathway activation, suggesting that PCDHGA9 negatively regulates Wnt signaling. Together, these data indicate that PCDHGA9 acts as a tumor suppressor with anti-proliferative activity and anti-invasive ability, and the reduction of PCDHGA9 could serve as an independent prognostic biomarker in GC.

Regulation of Wnt signaling by protocadherins

The ∼70 protocadherins comprise the largest group within the cadherin superfamily. Their diversity, the complexity of the mechanisms through which their genes are regulated, and their many critical functions in nervous system development have engendered a growing interest in elucidating the intracellular signaling pathways through which they act. Recently, multiple protocadherins across several subfamilies have been implicated as modulators of Wnt signaling pathways, and through this as potential tumor suppressors. Here, we review the extant data on the regulation by protocadherins of Wnt signaling pathways and components, and highlight some key unanswered questions that could shape future research.

PCDH8 inhibits glioma cell proliferation by negatively regulating the AKT/GSK3β/β-catenin signaling pathway

Protocadherin-8 (PCDH8), a member of the protocadherin superfamily of proteins, is frequently lost in numerous types of cancer. However, the role that PCDH8 serves in human glioma, and the molecular mechanisms underlying this, remain unclear. Data from the present study demonstrated that the expression levels of PCDH8 mRNA and protein were significantly decreased in human glioma tissue compared with normal brain tissue. This suggested that PCDH8 is associated with the development of glioma. Thus, the role of PCDH8 in glioma cell proliferation was investigated by silencing and overexpressing PCDH8 in U251 glioma cells. Overexpression of PCDH8 significantly inhibited glioma cell proliferation, while silencing of PCDH8 using small interfering RNA promoted glioma cell proliferation. Restoration of PCDH8 decreased phosphorylated (p)-Rac-α serine/threonine-protein kinase (AKT) [Threonine (T)308/Serine (S)473] and p-glycogen synthase kinase-3β (p-GSK3β) (S9) protein expression, thereby reducing the level of β-catenin when compared with the control. By contrast, silencing of PCDH8 increased levels of p-AKT (T308/S473) and p-GSK3β (S9), thereby increasing the level of β-catenin. In conclusion, the results of the present study suggested that PCDH8 suppressed glioma cell proliferation, and that the loss of PCDH8 may stimulate the proto-oncogene Wnt/β-catenin signaling pathway and therefore promote glioma cell proliferation.

Aberrant expression and functions of protocadherins in human malignant tumors

Protocadherins (PCDHs) are a group of transmembrane proteins belonging to the cadherin superfamily and are subdivided into "clustered" and "non-clustered" groups. PCDHs vary in both structure and interaction partners and thus regulate multiple biological responses in complex and versatile patterns. Previous researches showed that PCDHs regulated the development of brain and were involved in some neuronal diseases. Recently, studies have revealed aberrant expression of PCDHs in various human malignant tumors. The down-regulation or absence of PCDHs in malignant cells has been associated with cancer progression. Further researches suggest that PCDHs may play major functions as tumor suppressor by inhibiting the proliferation and metastasis of cancer cells. In this review, we focus on the altered expression of PCDHs and their roles in the development of cancer progression. We also discuss the potential mechanisms, by which PCDHs are aberrantly expressed, and its implications in regulating cancers.

Nuclear Receptor Corepressor 1 Expression and Output Declines with Prostate Cancer Progression

PURPOSE

Castration therapy in advanced prostate cancer eventually fails and leads to the development of castration-resistant prostate cancer (CRPC), which has no cure. Characteristic features of CRPC can be increased androgen receptor (AR) expression and altered transcriptional output. We investigated the expression of nuclear receptor corepressor 1 (NCOR1) in human prostate and prostate cancer and the role of NCOR1 in response to antiandrogens.

EXPERIMENTAL DESIGN

NCOR1 protein levels were compared between matched normal prostate and prostate cancer in 409 patient samples. NCOR1 knockdown was used to investigate its effect on bicalutamide response in androgen-dependent prostate cancer cell lines and transcriptional changes associated with the loss of NCOR1. NCOR1 transcriptional signature was also examined in prostate cancer gene expression datasets.

RESULTS

NCOR1 protein was detected in cytoplasm and nuclei of secretory epithelial cells in normal prostate. Both cytoplasmic and nuclear NCOR1 protein levels were lower in prostate cancer than in normal prostate. Prostate cancer metastases show significant decrease in NCOR1 transcriptional output. Inhibition of LNCaP cellular proliferation by bicalutamide requires NCOR1. NCOR1-regulated genes suppress cellular proliferation and mediate bicalutamide resistance. In the mouse, NCOR1 is required for bicalutamide-dependent regulation of a subset of the AR target genes.

CONCLUSIONS

In summary, we demonstrated that NCOR1 function declines with prostate cancer progression. Reduction in NCOR1 levels causes bicalutamide resistance in LNCaP cells and compromises response to bicalutamide in mouse prostate in vivo Clin Cancer Res; 22(15); 3937-49. ©2016 AACR.

Human Chromosome Y and Haplogroups; introducing YDHS Database

BACKGROUND

As the high throughput sequencing efforts generate more biological information, scientists from different disciplines are interpreting the polymorphisms that make us unique. In addition, there is an increasing trend in general public to research their own genealogy, find distant relatives and to know more about their biological background. Commercial vendors are providing analyses of mitochondrial and Y-chromosomal markers for such purposes. Clearly, an easy-to-use free interface to the existing data on the identified variants would be in the interest of general public and professionals less familiar with the field. Here we introduce a novel metadatabase YDHS that aims to provide such an interface for Y-chromosomal DNA (Y-DNA) haplogroups and sequence variants.

METHODS

The database uses ISOGG Y-DNA tree as the source of mutations and haplogroups and by using genomic positions of the mutations the database links them to genes and other biological entities. YDHS contains analysis tools for deeper Y-SNP analysis.

RESULTS

YDHS addresses the shortage of Y-DNA related databases. We have tested our database using a set of different cases from literature ranging from infertility to autism. The database is at http://www.semanticgen.net/ydhs

CONCLUSIONS

Y-chromosomal DNA (Y-DNA) haplogroups and sequence variants have not been in the scientific limelight, excluding certain specialized fields like forensics, mainly because there is not much freely available information or it is scattered in different sources. However, as we have demonstrated Y-SNPs do play a role in various cases on the haplogroup level and it is possible to create a free Y-DNA dedicated bioinformatics resource.

Nuclear signaling from cadherin adhesion complexes

The arrival of multicellularity in evolution facilitated cell-cell signaling in conjunction with adhesion. As the ectodomains of cadherins interact with each other directly in trans (as well as in cis), spanning the plasma membrane and associating with multiple other entities, cadherins enable the transduction of "outside-in" or "inside-out" signals. We focus this review on signals that originate from the larger family of cadherins that are inwardly directed to the nucleus, and thus have roles in gene control or nuclear structure-function. The nature of cadherin complexes varies considerably depending on the type of cadherin and its context, and we will address some of these variables for classical cadherins versus other family members. Substantial but still fragmentary progress has been made in understanding the signaling mediators used by varied cadherin complexes to coordinate the state of cell-cell adhesion with gene expression. Evidence that cadherin intracellular binding partners also localize to the nucleus is a major point of interest. In some models, catenins show reduced binding to cadherin cytoplasmic tails favoring their engagement in gene control. When bound, cadherins may serve as stoichiometric competitors of nuclear signals. Cadherins also directly or indirectly affect numerous signaling pathways (e.g., Wnt, receptor tyrosine kinase, Hippo, NFκB, and JAK/STAT), enabling cell-cell contacts to touch upon multiple biological outcomes in embryonic development and tissue homeostasis.

The many faces of neuroendocrine differentiation in prostate cancer progression

In normal prostate, neuroendocrine (NE) cells are rare and interspersed among the epithelium. These cells are believed to provide trophic signals to epithelial cell populations through the secretion of an abundance of neuropeptides that can diffuse to influence surrounding cells. In the setting of prostate cancer (PC), NE cells can also stimulate surrounding prostate adenocarcinoma cell growth, but in some cases adenocarcinoma cells themselves acquire NE characteristics. This epithelial plasticity is associated with decreased androgen receptor (AR) signaling and the accumulation of neuronal and stem cell characteristics. Transformation to an NE phenotype is one proposed mechanism of resistance to contemporary AR-targeted treatments, is associated with poor prognosis, and thought to represent up to 25% of lethal PCs. Importantly, the advent of high-throughput technologies has started to provide clues for understanding the complex molecular profiles of tumors exhibiting NE differentiation. Here, we discuss these recent advances, the multifaceted manner by which an NE-like state may arise during the different stages of disease progression, and the potential benefit of this knowledge for the management of patients with advanced PC.

Beyond E-cadherin: roles of other cadherin superfamily members in cancer

Loss of cadherin 1 (CDH1; also known as epithelial cadherin (E-cadherin)) is used for the diagnosis and prognosis of epithelial cancers. However, it should not be ignored that the superfamily of transmembrane cadherin proteins encompasses more than 100 members in humans, including other classical cadherins, numerous protocadherins and cadherin-related proteins. Elucidation of their roles in suppression versus initiation or progression of various tumour types is a young but fascinating field of molecular cancer research. These cadherins are very diverse in both structure and function, and their mutual interactions seem to influence biological responses in complex and versatile ways.

Cross modulation between the androgen receptor axis and protocadherin-PC in mediating neuroendocrine transdifferentiation and therapeutic resistance of prostate cancer

Castration-resistant prostate cancers (CRPCs) that relapse after androgen deprivation therapies (ADTs) are responsible for the majority of mortalities from prostate cancer (PCa). While mechanisms enabling recurrent activity of androgen receptor (AR) are certainly involved in the development of CRPC, there may be factors that contribute to the process including acquired neuroendocrine (NE) cell-like behaviors working through alternate (non-AR) cell signaling systems or AR-dependent mechanisms. In this study, we explore the potential relationship between the AR axis and a novel putative marker of NE differentiation, the human male protocadherin-PC (PCDH-PC), in vitro and in human situations. We found evidence for an NE transdifferentiation process and PCDH-PC expression as an early-onset adaptive mechanism following ADT and elucidate AR as a key regulator of PCDH-PC expression. PCDH-PC overexpression, in turn, attenuates the ligand-dependent activity of the AR, enabling certain prostate tumor clones to assume a more NE phenotype and promoting their survival under diverse stress conditions. Acquisition of an NE phenotype by PCa cells positively correlated with resistance to cytotoxic agents including docetaxel, a taxane chemotherapy approved for the treatment of patients with metastatic CRPC. Furthermore, knockdown of PCDH-PC in cells that have undergone an NE transdifferentiation partially sensitized cells to docetaxel. Together, these results reveal a reciprocal regulation between the AR axis and PCDH-PC signals, observed both in vitro and in vivo, with potential implications in coordinating NE transdifferentiation processes and progression of PCa toward hormonal and chemoresistance.

Characterizing the role of PCDH9 in the regulation of glioma cell apoptosis and invasion

PCDH9, a member of the protocadherin superfamily, is frequently lost in many different cancer types. This study aimed to detect PCDH9 expression in glioma tissues. This study also assessed the effects of PCDH9 expression in two different glioma cell lines. This was accomplished by manipulating PCDH9 expression in these glioma cell lines. The data showed that the expression of PCDH9 mRNA and protein was significantly decreased in gliomas compared to normal brain tissues. Lentivirus carrying PCDH9 cDNA restored PCDH9 expression in the U87 and U251 glioma cell lines. PCDH9 restoration in these cell lines reduced tumor cell viability, induced apoptosis, and caused G0/G1 cell cycle arrest. PCDH9 expression also suppressed the colony formation ability and invasion capacity of U87 and U251 cells. Molecularly, the restoration of PCDH9 expression upregulated Bax protein expression, but downregulated Bcl-2 and cyclin D1 expression. These data from the current study suggest that the loss of PCDH9 expression could contribute to glioma development and/or progression. Further studies will evaluate PCDH9 expression as a biomarker for the early detection of gliomas and as a prognostic indicator for this cancer type.

A peptide derived from phage display library exhibits anti-tumor activity by targeting GRP78 in gastric cancer multidrug resistance cells

Multidrug resistance (MDR) remains a significant challenge to the clinical treatment of gastric cancer (GC). In the present study, using a phage display approach combined with MTT assays, we screened a specific peptide GMBP1 (Gastric cancer MDR cell-specific binding peptide), ETAPLSTMLSPY, which could bind to the surface of GC MDR cells specifically and reverse their MDR phenotypes. Immunocytochemical staining showed that the potential receptor of GMBP1 was located at the membrane and cytoplasm of MDR cells. In vitro and in vivo drug sensitivity assays, FACS analysis and Western blotting confirmed that GMBP1 was able to re-sensitize MDR cells to chemical drugs. Western blotting and proteomic approaches were used to screen the receptor of GMBP1, and GRP78, a MDR-related protein, was identified as a receptor of GMBP1. This result was further supported by immunofluoresence microscopy and Western blot. Additionally, Western blotting demonstrated that pre-incubation of GMBP1 in MDR cells greatly diminished MDR1, Bcl-2 and GRP78 expression but increased the expression of Bax, whereas downregulation of GRP78, function as a receptor and directly target for GMBP1, only inhibited MDR1 expression. Our findings suggest that GMBP1 could re-sensitize GC MDR cells to a variety of chemotherapeutic agents and this role might be mediated partly through down-regulating GRP78 expression and then inhibiting MDR1 expression. These findings indicate that peptide GMBP1 likely recognizes a novel GRP78 receptor and mediates cellular activities associated with the MDR phenotype, which provides new insight into research on the management of MDR in gastric cancer cells.

The protocadherin 11X/Y (PCDH11X/Y) gene pair as determinant of cerebral asymmetry in modern Homo sapiens

Annett's right-shift theory proposes that human cerebral dominance (the functional and anatomical asymmetry or torque along the antero-posterior axis) and handedness are determined by a single “right-shift” gene. Familial transmission of handedness and specific deviations of cerebral dominance in sex chromosome aneuploidies implicate a locus within an X–Y homologous region of the sex chromosomes. The Xq21.3/Yp11.2 human-specific region of homology includes the protocadherin 11X/Y (PCDH11X/Y) gene pair, which encode cell adhesion molecules subject to accelerated evolution following the separation of the human and chimpanzee lineages six million years ago. PCDH11X and PCDH11Y, differentially regulated by retinoic acid, are highly expressed in the ventricular zone, subplate, and cortical plate of the developing cerebral cortex. Both proteins interact with β-catenin, a protein that plays a role in determining axis formation and regulating cortical size. In this way, the PCDH11X/Y gene pair determines cerebral asymmetry by initiating the right shift in Homo sapiens.

Delta-protocadherins in health and disease

The protocadherin family comprises clustered and nonclustered protocadherin genes. The nonclustered genes encode mainly δ-protocadherins, which deviate markedly from classical cadherins. They can be subdivided phylogenetically into δ0-protocadherins (protocadherin-20), δ1-protocadherins (protocadherin-1, -7, -9, and -11X/Y), and δ2-protocadherins (protocadherin-8, -10, -17, -18, and -19). δ-Protocadherins share a similar gene structure and are expressed as multiple alternative splice forms differing mostly in their cytoplasmic domains (CDs). Some δ-protocadherins reportedly show cell-cell adhesion properties. Individual δ-protocadherins appear to be involved in specific signaling pathways, as they interact with proteins such as TAF1/Set, TAO2β, Nap1, and the Frizzled-7 receptor. The spatiotemporally restricted expression of δ-protocadherins in various tissues and species and their functional analysis suggest that they play multiple, tightly regulated roles in vertebrate development. Furthermore, several δ-protocadherins have been implicated in neurological disorders and in cancers, highlighting the importance of scrutinizing their properties and their dysregulation in various pathologies.

A fresh look at the male-specific region of the human Y chromosome

The Chromosome-centric Human Proteome Project (C-HPP) aims to systematically map the entire human proteome with the intent to enhance our understanding of human biology at the cellular level. This project attempts simultaneously to establish a sound basis for the development of diagnostic, prognostic, therapeutic, and preventive medical applications. In Iran, current efforts focus on mapping the proteome of the human Y chromosome. The male-specific region of the Y chromosome (MSY) is unique in many aspects and comprises 95% of the chromosome's length. The MSY continually retains its haploid state and is full of repeated sequences. It is responsible for important biological roles such as sex determination and male fertility. Here, we present the most recent update of MSY protein-encoding genes and their association with various traits and diseases including sex determination and reversal, spermatogenesis and male infertility, cancers such as prostate cancers, sex-specific effects on the brain and behavior, and graft-versus-host disease. We also present information available from RNA sequencing, protein-protein interaction, post-translational modification of MSY protein-coding genes and their implications in biological systems. An overview of Human Y chromosome Proteome Project is presented and a systematic approach is suggested to ensure that at least one of each predicted protein-coding gene's major representative proteins will be characterized in the context of its major anatomical sites of expression, its abundance, and its functional relevance in a biological and/or medical context. There are many technical and biological issues that will need to be overcome in order to accomplish the full scale mapping.

Genome-wide association study of prognosis in advanced non-small cell lung cancer patients receiving platinum-based chemotherapy

PURPOSE

Genetic variation may influence chemotherapy response and overall survival in cancer patients.

EXPERIMENTAL DESIGN

We conducted a genome-wide scan in 535 advanced-stage non-small cell lung cancer (NSCLC) patients from two independent cohorts (307 from Nanjing and 228 from Beijing). A replication was carried out on an independent cohort of 340 patients from Southeastern China followed by a second validation on 409 patients from the Massachusetts General Hospital (Boston, MA).

RESULTS

Consistent associations with NSCLC survival were identified for five single-nucleotide polymorphisms (SNP) in Chinese populations with P values ranging from 3.63 × 10(-5) to 4.19 × 10(-7) in the additive genetic model. The minor allele of three SNPs (rs7629386 at 3p22.1, rs969088 at 5p14.1, and rs3850370 at 14q24.3) were associated with worse NSCLC survival while 2 (rs41997 at 7q31.31 and rs12000445 at 9p21.3) were associated with better NSCLC survival. In addition, rs7629386 at 3p22.1 (CTNNB1) and rs3850370 at 14q24.3 (SNW1-ALKBH1-NRXN3) were further replicated in the Caucasian population.

CONCLUSION

In this three-stage genome-wide association studies, we identified five SNPs as markers for survival of advanced-stage NSCLC patients treated with first-line platinum-based chemotherapy in Chinese Han populations. Two of these SNPs, rs7629386 and rs3850370, could also be markers for survival among Caucasian patients.

Protocadherin 11X/Y a human-specific gene pair: an immunohistochemical survey of fetal and adult brains

Protocadherins 11X and 11Y are cell adhesion molecules of the δ1-protocadherin family. Pcdh11X is present throughout the mammalian radiation; however, 6 million years ago (MYA), a reduplicative translocation of the Xq21.3 block onto what is now human Yp11 created the Homo sapiens-specific PCDH11Y. Therefore, modern human females express PCDH11X whereas males express both PCDH11X and PCDH11Y. PCDH11X/Y has been subject to accelerated evolution resulting in human-specific changes to both proteins, most notably 2 cysteine substitutions in the PCDH11X ectodomain that may alter binding characteristics. The PCDH11X/Y gene pair is postulated to be critical to aspects of human brain evolution related to the neural correlates of language. Therefore, we raised antibodies to investigate the temporal and spatial expression of PCDH11X/Y in cortical and sub-cortical areas of the human fetal brain between 12 and 34 postconceptional weeks. We then used the antibodies to determine if this expression was consistent in a series of adult brains. PCDH11X/Y immunoreactivity was detectable at all developmental stages. Strong expression was detected in the fetal neocortex, ganglionic eminences, cerebellum, and inferior olive. In the adult brain, the cerebral cortex, hippocampal formation, and cerebellum were strongly immunoreactive, with expression also detectable in the brainstem.

JS-K, a glutathione/glutathione S-transferase-activated nitric oxide releasing prodrug inhibits androgen receptor and WNT-signaling in prostate cancer cells

BACKGROUND

Nitric oxide (NO) and its oxidative reaction products have been repeatedly shown to block steroid receptor function via nitrosation of zinc finger structures in the DNA-binding domain (DBD). In consequence NO-donors could be of special interest for the treatment of deregulated androgen receptor(AR)-signaling in castration resistant prostate cancer (CRPC).

METHODS

Prostate cancer (PCa) cells were treated with JS-K, a diazeniumdiolate derivate capable of generating large amounts of intracellular NO following activation by glutathione S-transferase. Generation of NO was determined indirectly by the detection of nitrate in tissue culture medium or by immunodetection of nitrotyrosine in the cytoplasm. Effects of JS-K on intracellular AR-levels were determined by western blotting. AR-dimerization was analyzed by mammalian two hybrid assay, nuclear translocation of the AR was visualized in PCa cells transfected with a green fluorescent AR-Eos fusion protein using fluorescence microscopy. Modulation of AR- and WNT-signalling by JS-K was investigated using reporter gene assays. Tumor cell proliferation following JS-K treatment was measured by MTT-Assay.

RESULTS

The NO-releasing compound JS-K was shown to inhibit AR-mediated reporter gene activity in 22Rv1 CRPC cells. Inhibition of AR signaling was neither due to an inhibition of nuclear import nor to a reduction in AR-dimerization. In contrast to previously tested NO-donors, JS-K was able to reduce the intracellular concentration of functional AR. This could be attributed to the generation of extremely high intracellular levels of the free radical NO as demonstrated indirectly by high levels of nitrotyrosine in JS-K treated cells. Moreover, JS-K diminished WNT-signaling in AR-positive 22Rv1 cells. In line with these observations, castration resistant 22Rv1 cells were found to be more susceptible to the growth inhibitory effects of JS-K than the androgen dependent LNCaP which do not exhibit an active WNT-signaling pathway.

CONCLUSIONS

Our results suggest that small molecules able to inhibit WNT- and AR-signaling via NO-release represent a promising platform for the development of new compounds for the treatment of CRPC.

Inhibition of glycogen synthase kinase-3β counteracts ligand-independent activity of the androgen receptor in castration resistant prostate cancer

In order to generate genomic signals, the androgen receptor (AR) has to be transported into the nucleus upon androgenic stimuli. However, there is evidence from in vitro experiments that in castration-resistant prostate cancer (CRPC) cells the AR is able to translocate into the nucleus in a ligand-independent manner. The recent finding that inhibition of the glycogen-synthase-kinase 3β (GSK-3β) induces a rapid nuclear export of the AR in androgen-stimulated prostate cancer cells prompted us to analyze the effects of a GSK-3β inhibition in the castration-resistant LNCaP sublines C4-2 and LNCaP-SSR. Both cell lines exhibit high levels of nuclear AR in the absence of androgenic stimuli. Exposure of these cells to the maleimide SB216763, a potent GSK-3β inhibitor, resulted in a rapid nuclear export of the AR even under androgen-deprived conditions. Moreover, the ability of C4-2 and LNCaP-SSR cells to grow in the absence of androgens was diminished after pharmacological inhibition of GSK-3β in vitro. The ability of SB216763 to modulate AR signalling and function in CRPC in vivo was additionally demonstrated in a modified chick chorioallantoic membrane xenograft assay after systemic delivery of SB216763. Our data suggest that inhibition of GSK-3β helps target the AR for export from the nucleus thereby diminishing the effects of mislocated AR in CRPC cells. Therefore, inhibition of GSK-3β could be an interesting new strategy for the treatment of CRPC.

Comparative proteomics analysis of midgut samples from Takifugu rubripes exposed to excessive fluoride: initial molecular response to fluorosis

Comparative proteomic analysis was performed to identify proteins in the midgut of Takifugu rubripes (Fugu) in response to excessive fluoride. Sixteen fish were randomly divided into a control group and an experimental group. The control group was raised in soft water alone (F⁻= 0.4 mg/L), whereas the experimental group was raised in the soft water with sodium fluoride at a high concentration of 35 mg/L. After 3 days, proteins were extracted from the fish midgut and then subjected to two-dimensional (2-D) PAGE analysis. The matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI TOF/TOF MS) was applied to identify the differential expressed proteins between the two groups. Among 377 and 528 proteins detected in the control and the treated groups, respectively, 17 proteins were up-regulated and 218 were down-regulated (P < 0.01) in the fluoride-treated group, compared with the control group. We further analyzed 17 up-regulated proteins by MALDI TOF/TOF MS and identified 12 of them by MASCOT, of which eight were known proteins. Consistent with their annotated functions, these proteins seem to be involved in apoptosis and other functions related to fluorosis. Our results provide initial insights into the effects of excessive fluoride exposure on physiological and biochemical functions of Fugu midgut as well as on the toxicological mechanism of fluoride in both fish and human.

Non-clustered protocadherin

The cadherin family is classified into classical cadherins, desmosomal cadherins and protocadherins (PCDHs). Genomic structures distinguish between PCDHs and other cadherins, and between clustered and non-clustered PCDHs. The phylogenetic analysis with full sequences of non-clustered PCDHs enabled them to be further classified into three subgroups: δ1 (PCDH1, PCDH7, PCDH9, PCDH11 and PCDH20), δ2 (PCDH8, PCDH10, PCDH12, PCDH17, PCDH18 and PCDH19) and ε (PCDH15, PCDH16, PCDH21 and MUCDHL). ε-PCDH members except PCDH21 have either higher or lower numbers of cadherin repeats than those of other PCDHs. Non-clustered PCDHs are expressed predominantly in the nervous system and have spatiotemporally diverse expression patterns. Especially, the region-specific expressions of non-clustered PCDHs have been observed in cortical area of early postnatal stage and in caudate putaman and/or hippocampal formation of mature brains, suggesting that non-clustered PCDHs play roles in the circuit formation and maintenance. The non-clustered PCDHs appear to have homophilic/heterophilc cell-cell adhesion properties, and each member has diverse cell signaling partnership distinct from those of other members (PCDH7/TAF1; PCDH8/TAO2β; PCDH10/Nap1; PCDH11/β-catenin; PCDH18/mDab1). Furthermore, each PCDH has several isoforms with differential cytoplasmic sequences, suggesting that one PCDH isoform could activate intracellular signaling differential from other isoforms. These facts suggest that non-clustered PCDHs play roles as a mediator of a regulator of other molecules as well as cell-cell adhesion. Furthermore, some non-clustered PCDHs have been considered to be involved in neuronal diseases such as autism-spectrum disorders, schizophrenia, and female-limited epilepsy and cognitive impairment, suggesting that they play multiple, tightly regulated roles in normal brain function. In addition, some non-clustered PCDHs have been suggested as candidate tumor suppressor genes in several tissues. Although molecular adhesive and regulatory properties of some PCDHs began to be unveiled, the endeavor to understand the molecular mechanism of non-clustered PCDH is still in its infancy and requires future study.

Relaxin drives Wnt signaling through upregulation of PCDHY in prostate cancer

BACKGROUND

Relaxin, a potent peptide hormone of the insulin-like family normally produced and secreted by the human prostate, is upregulated in castrate resistant prostate cancer progression. In various tissues, relaxin increases angiogenesis and cell motility through upregulation of vascular endothelial growth factor, matrix metalloproteases, and nitric oxide, and therefore maybe an attractive target for cancer therapeutics.

METHODS

To examine the role of relaxin in prostate cancer progression, LNCaP cells stably transfected with relaxin (LNCaP(RLN)) were used to form xenograft tumors, and microarray expression analysis was subsequently performed to determine novel pathways regulated by relaxin. Prostate cancer tissue microarrays from patient samples were stained by immunohistochemistry for further validation and correlation of the findings.

RESULTS

Expression analysis identified novel relaxin regulated pathways, including the ProtocadherinY (PCDHY)/Wnt pathway. PCDHY, which upregulates Wnt11, has previously been shown to stabilize beta-catenin, causing beta-catenin to translocate from the cytoplasmic membrane to the nucleus and initiate TCF-mediated signaling. LNCaP(RLN) xenografts exhibit increased PCDHY expression and increased cytoplasmic localization of beta-catenin, suggesting relaxin directs Wnt11 overexpression through PCDHY upregulation. Similarly, prostate cancer samples from patients who have undergone androgen ablation have increased Wnt11 expression, which is further upregulated in castrate resistant tissues. Like relaxin, Wnt11, and PCDHY are negatively regulated by androgens, and further analysis indicated that the overexpression of relaxin results in dysregulation of androgen-regulated genes.

CONCLUSIONS

These data suggest that prostate cancer cell motility and altered androgen receptor activity attributed to relaxin may be mediated in part by Wnt11.

Involvement of members of the cadherin superfamily in cancer

We review the role of cadherins and cadherin-related proteins in human cancer. Cellular and animal models for human cancer are also dealt with whenever appropriate. E-cadherin is the prototype of the large cadherin superfamily and is renowned for its potent malignancy suppressing activity. Different mechanisms for inactivating E-cadherin/CDH1 have been identified in human cancers: inherited and somatic mutations, aberrant protein processing, increased promoter methylation, and induction of transcriptional repressors such as Snail and ZEB family members. The latter induce epithelial mesenchymal transition, which is also associated with induction of "mesenchymal" cadherins, a hallmark of tumor progression. VE-cadherin/CDH5 plays a role in tumor-associated angiogenesis. The atypical T-cadherin/CDH13 is often silenced in cancer cells but up-regulated in tumor vasculature. The review also covers the status of protocadherins and several other cadherin-related molecules in human cancer. Perspectives for emerging cadherin-related anticancer therapies are given.

The protocadherin 11X/Y gene pair as a putative determinant of cerebral dominance in Homo sapiens

The cerebral torque, a bias from right frontal to left occipital across the anterior–posterior axis is arguably the defining feature of the human brain, and the foundation for language. What is its genetic basis? Handedness and anatomical data suggest that this torque is specific to humans relative to the extant great apes. Asymmetry deficits associated with sex chromosome aneuploidies implicate loci on both the X and Y chromosomes. A block from the Xq21.3 band was duplicated to the Y chromosome 6 million years ago (close to, and a possible cause of the chimpanzee/hominin separation) containing the human-specific gene pair PCDH11X/Y. PCDH11Y has been subject to positive selection through hominin evolution including 18 amino-acid changes to the longest isoform of the protein. The PCDH11X protein has been subject to five substitutions including two cysteines in the ectodomain. The gene pair can account for sex differences, for example, in cerebral asymmetry and language.

Inhibition of glycogen synthase kinase-3 in androgen-responsive prostate cancer cell lines: are GSK inhibitors therapeutically useful?

The glycogen synthase kinase 3 (GSK-3) is a serine/threonine kinase widely expressed in mammalian tissues. Initially identified by its ability to modulate glycogen synthesis, GSK-3 turned out to be a multifunctional enzyme, able to phosphorylate many proteins, including members of the steroid receptor superfamily. Although GSK-3 was shown to phosphorylate the androgen receptor (AR), its effects on AR transcriptional activity remain controversial. Analysis of short hairpin RNA (shRNA)-mediated downmodulation of GSK-3 proteins in prostate cancer cells showed a reduction in AR transcriptional activity and AR protein levels. Pharmacological GSK-3 inhibitors such as the maleimide SB216763 or the aminopyrazole GSK inhibitor XIII inhibited AR-dependent reporter gene activity and AR expression in vitro. Analysis of androgen-induced nuclear translocation of the AR was performed in PC3 cells transfected with pAR-t1EosFP coding for EosAR, a green fluorescent AR fusion protein. When grown in presence of androgens, EosAR was predominantly nuclear. Incubation with SB216763 before and after androgen treatment almost completely reduced nuclear EosAR. In contrast, the thiazole-containing urea compound AR-A014418 increased rather than decreased AR-expression/function. Although not all GSK inhibitors affected AR-stability/function, our observations suggest a potential new therapeutic application for some of these compounds in prostate cancer.

Neuroendocrine differentiation in prostate cancer: from lab to bedside

OBJECTIVES

To discuss the current knowledge on induction, production, sustenance and promotion of neuroendocrine differentiation in human prostate cancer.

METHODS

Review of the literature using PubMed search and scientific journal publications.

RESULTS

Morphological evidence explains some functional relationship between neuroendocrine and neoplastic surrounding cells. Transdifferentiation phenomenon and new biochemical pathways could be included in the development of androgen independence and prostate cancer progression.

CONCLUSION

Multiple evidence seems to confirm that a synergistic functional network between epithelial PSA secretory cells and neuroendocrine intraprostatic system is the main trigger for the induction and sustenance of neuroendocrine differentiation. The development of new antineoplastic molecules should consider the multiple interference of the intercellular network.

Activation of targeted necrosis by a p53 peptide: a novel death pathway that circumvents apoptotic resistance

Cancer cells escape apoptosis by intrinsic or acquired mechanisms of drug resistance. An alternative strategy to circumvent resistance to apoptosis could be through redirection into other death pathways, such as necrosis. However, necrosis is a nonspecific, nontargeted process resulting in cell lysis and inflammation of both cancer and normal cells and is therefore not a viable alternative. Here, we report that a C-terminal peptide of p53, called p53p-Ant, induced targeted necrosis only in multiple mutant p53 human prostate cancer lines and not normal cells, because the mechanism of cytotoxicity by p53p-Ant is dependent on the presence of high levels of mutant p53. Topotecan- and paclitaxel-resistant prostate cancer lines were as sensitive to p53p-Ant-induced targeted necrosis as parental lines. A massive loss of ATP pools and intracellular generation of reactive oxygen species was involved in the mechanism of targeted necrosis, which was inhibited by O(2)(.) scavengers. We hypothesize that targeted necrosis by p53p-Ant is dependent on mutant p53, is mediated by O(2)(.) loss and ATP, and can circumvent chemotherapy resistance to apoptosis. Targeted necrosis, as an alternative pathway for selective killing of cancer cells, may overcome the problems of nonspecificity in utilizing the necrotic pathway.

New Insights into Prostate Cancer Biology

Prostate cancer is common, biologically heterogeneous, and protean in its clinical manifestations. Through the use and analysis of isogenic cell lines, xeno-grafts, transgenic mice, and human tumors, one begins to deconvolute the precise biologic mechanisms that combine to create the native complexity and heterogeneity of this disease. In this article, the authors have underscored compelling recent discoveries in prostate cancer so as to provide the reader with molecular paradigms with which to interpret future insights into its biology. Although it was inevitably necessary to omit a significant amount of important research in prostate cancer, the work discussed here is exemplary of current prostate cancer research. Looking forward, it is hoped that the collective work of mapping genetic and biologic interactions among key regulators of prostate epithelial cells, epithelial-stromal interactions, host immune system, and host genetics will eventually result in a comprehensive understanding of prostate cancer. Although it is likely that the molecular characteristics of an individual's prostate cancer will be analyzed using limited molecular tools in the near future, eventual application of genomic technologies and nanotechnology offers the promise of robust future characterization. Such a characterization is likely to be required to maximize our ability to optimize and individualize preventive and treatment strategies.

Protocadherin-PC promotes androgen-independent prostate cancer cell growth

BACKGROUND

Protocadherin-PC (PCDH-PC) expression is upregulated in apoptosis-resistant sublines of the LNCaP human prostate cancer (CaP) cell line. Here, we assess the role of PCDH-PC in CaP cells and its mRNA expression in human prostate tissues.

METHODS

LNCaP cells transfected with PCDH-PC were tested for their ability to grow in vitro and in vivo in androgen-deprived conditions. PCDH-PC mRNA expression was evaluated by semi-quantitative RT-PCR and by in situ hybridization.

RESULTS

PCDH-PC expression induced Wnt signaling in CaP cells and permitted androgen-independent growth of hormone-sensitive CaP cells. Expression of PCDH-PC-homologous transcripts was low and restricted to some epithelial cells in normal tissue and to CaP cells in tumors. However, hormone-resistant CaP cells expressed significantly higher levels of PCDH-PC-related mRNA.

CONCLUSIONS

Our findings suggest a novel mechanism for the progression of CaP involving expression of PCDH-PC. This novel protocadherin induces Wnt signaling, promotes malignant behavior and hormone-resistance of CaP cells.

Protocadherin 15 (PCDH15): a new secreted isoform and a potential marker for NK/T cell lymphomas

Natural killer cells are well known to play an important role in immune defense against tumor development and viral infections. To further characterize new functionally relevant structures in these cells, we studied a series of monoclonal antibodies that we have raised against the NK cell line YT. One of these antibodies previously described as AY19, recognizes a 85 kD surface glycoprotein. Here we report the identification of a new secreted isoform of protocadherin 15, PCDH15C, which represents a potential associated protein for p85. Importantly, whereas protocadherins are absent from the surface of normal hematopoietic cells, we describe, for the first time, that PCDH15 is expressed in cytotoxic tumor-derived T- and NK-cell lines as well as in biopsies of nasal NK/T-cell lymphomas.

Frequent silencing of the candidate tumor suppressor PCDH20 by epigenetic mechanism in non-small-cell lung cancers

Protocadherins are a major subfamily of the cadherin superfamily, but little is known about their functions and intracellular signal transduction. We identified a homozygous loss of protocadherin 20 (PCDH20, 13q21.2) in the course of a program to screen a panel of non-small-cell lung cancer (NSCLC) cell lines (1 of 20 lines) for genomic copy number aberrations using an in-house array-based comparative genomic hybridization. PCDH20 mRNA was expressed in normal lung tissue but was not expressed in the majority of NSCLC cell lines without a homozygous deletion of this gene (10 of 19 lines, 52.6%). Expression of PCDH20 mRNA was restored in gene-silenced NSCLC cells after treatment with 5-aza 2'-deoxycytidine. The DNA methylation status of the PCDH20 CpG-rich region correlated inversely with the expression of the gene and a putative target region for methylation showed clear promoter activity in vitro. Methylation of this PCDH20 promoter was frequently observed in primary NSCLC tissues (32 of 59 tumors, 54.2%). Among our primary NSCLC cases, the methylated PCDH20 seemed to be associated with a shorter overall survival (P = 0.0140 and 0.0211 in all and stage I tumors, respectively; log-rank test), and a multivariate analysis showed that the PCDH20 methylation status was an independent prognosticator. Moreover, restoration of PCDH20 expression in NSCLC cells reduced cell numbers in colony formation and anchorage-independent assays. These results suggest that epigenetic silencing by hypermethylation of the CpG-rich promoter region of PCDH20 leads to loss of PCDH20 function, which may be a factor in the carcinogenesis of NSCLC.

Overexpression of PKCε sensitizes LNCaP human prostate cancer cells to induction of apoptosis by bryostatin 1

Phorbol 12-myristate 13-acetate (PMA)-induced apoptosis of androgen sensitive LNCaP human prostate cancer cells is a well known phenomenon that involves prolonged translocation of multiple protein kinase C (PKC) isozymes to nonnuclear membranes. We have shown recently that PMA-induced death of C4-2 cells, androgen hypersensitive derivatives of LNCaP cells, requires both PKCdelta and a redundant pathway that includes PKCs alpha and epsilon. In contrast, it has been reported that overexpression of murine PKCepsilon in LNCaP cells renders those cells resistant to PMA-induced death, as well as androgen insensitive. Here we report that inducible or constitutive overexpression of human PKCepsilon does not alter the sensitivity of LNCaP cells to either PMA or androgen, nor does it alter expression of caveolin-1 or phosphorylated Rb, reported effects of overexpression of murine PKCepsilon. Moreover, overexpression of very high amounts of PKCepsilon sensitized LNCaP cells to induction of apoptosis by bryostatin 1, a non tumor-promoting activator and down-regulator of PKC isozymes that blocks PMA-induced apoptosis of parental LNCaP cells, mimicked our previous results with overexpression of PKCalpha in LNCaP cells. Given reports that overexpression of PKCepsilon is frequent in human prostate tumors, our results may have important implications for a potential prostate cancer therapy.

A human- and male-specific protocadherin that acts through the wnt signaling pathway to induce neuroendocrine transdifferentiation of prostate cancer cells

Protocadherin-PC (PCDH-PC) is a gene on the human Y chromosome that is selectively expressed in apoptosis- and hormone-resistant human prostate cancer cells. The protein encoded by PCDH-PC is cytoplasmically localized and has a small serine-rich domain in its COOH terminus that is homologous to the beta-catenin binding site of classical cadherins. Variants of prostate cancer cells that express PCDH-PC have high levels of nuclear beta-catenin protein and increased wnt-signaling. In this study, we show that transfection of human prostate cancer cells (LNCaP) with PCDH-PC or culture of these cells in androgen-free medium (a condition that up-regulates PCDH-PC expression) activates wnt signaling as assessed by nuclear accumulation of beta-catenin, increased expression of luciferase from a reporter vector promoted by Tcf binding elements and increased expression of wnt target genes. Moreover, LNCaP cells transfected with PCDH-PC or grown in androgen-free medium transdifferentiate to neuroendocrine-like cells marked by elevated expression of neuron-specific enolase and chromogranin-A. Neuroendocrine transdifferentiation was also observed when LNCaP cells were transfected by stabilized beta-catenin. Increased wnt signaling and neuroendocrine transdifferentiation of LNCaP cells induced by culture in androgen-free medium was suppressed by short interfering RNAs that target PCDH-PC as well as by dominant-negative Tcf or short interfering RNA against beta-catenin, supporting the hypothesis that increased expression of PCDH-PC is driving neuroendocrine transdifferentiation by activating wnt signaling. These findings have significant implications for the process through which prostate cancers progress to hormone resistance in humans.

Phorbol ester-induced apoptosis of C4-2 cells requires both a unique and a redundant protein kinase C signaling pathway

Phorbol 12-myristate 13-acetate (PMA) potently induces apoptosis of LNCaP human prostate cancer cells. Here, we show that C4-2 cells, androgen-hypersensitive derivatives of LNCaP cells, also are sensitive to PMA-induced apoptosis. Previous reports have implicated activation of protein kinase C (PKC) isozymes alpha and delta in PMA-induced LNCaP apoptosis using overexpression, pharmacological inhibitors, and dominant-negative constructs, but have left unresolved if other isozymes are involved, if there are separate requirements for individual PKC isozymes, or if there is redundancy. We have resolved these questions in C4-2 cells using stable expression of short hairpin RNAs to knock down expression of specific PKC isozymes individually and in pairs. Partial knockdown of PKCdelta inhibited PMA-induced C4-2 cell death almost completely, whereas near-complete knockdown of PKCalpha had no effect. Knockdown of PKCepsilon alone had no effect, but simultaneous knockdown of both PKCalpha and PKCepsilon in C4-2 cells that continued to express normal levels of PKCdelta inhibited PMA-induced apoptosis. Thus, our data indicate that there is an absolute requirement for PKCdelta in PMA-induced C4-2 apoptosis but that the functions of PKCalpha and PKCepsilon in apoptosis induction are redundant, such that either one (but not both) is required. Investigation of PMA-induced events required for LNCaP and C4-2 apoptosis revealed that p38 activation is dependent on PKCdelta, whereas induction of retinoblastoma protein hypophosphorylation requires both PKC signaling pathways and is downstream of p38 activation in the PKCdelta pathway.

Differentially expressed genes between solitary large hepatocellular carcinoma and nodular hepatocellular carcinoma

AIM: To study the difference in gene expression between solitary large hepatocellular carcinoma (SLHCC) and nodular hepatocellular carcinoma (NHCC).

METHODS: Polymerase chain reaction (PCR) products of 8464 human genes were spotted on a chip in array. DNAs were then fixed on a glass plate. Total RNA was isolated from freshly excised human SLHCC (n = 7) and NHCC (n = 15) tissues, and was reversely transcribed to cDNAs with the incorporation of fluorescent dUTP for preparation of hybridization probes. The mixed probes were then hybridized to the cDNA microarray. After highly stringent washing, cDNA microarray was scanned for the fluorescent signals to display the difference between the two kinds of HCC. In addition, the expression of RhoC and protocadherin LKC was also detected with the reverse transcriptase polymerase chain reaction (RT-PCR) method.

RESULTS: Among the 8464 human genes, 668 (7.89%) genes were expressed differentially at the mRNA levels between SLHCC and NHCC. Three hundred and fifty five (4.19%) genes, including protocadherin LKC, were up-regulated, whereas 313 (3.70%) genes, including RhoC, were down-regulated. The mRNA expression levels of RhoC and protocadherin LKC were confirmed by RT-PCR. Analysis of differentially expressed genes confirmed that our molecular data obtained by cDNA microarray were consistent with the published biochemical and clinical observations of SLHCC and NHCC.

CONCLUSION: cDNA microarray is an effective technique in screening the difference in gene expression between SLHCC and NHCC. Many of these differentially expressed genes are involved in the invasion and metastasis of HCC. Further analysis of these genes will help to understand the different molecular mechanisms of SLHCC and NHCC.

A Concentrated Aglycone Isoflavone Preparation (GCP) That Demonstrates Potent Anti-Prostate Cancer ActivityIn vitroandIn vivo

PURPOSE

Isoflavones have anticancer activities, but naturally occurring isoflavones are predominantly glycosylated and poorly absorbed. Genistein combined polysaccharide (GCP; Amino Up Chemical Co., Sapporo, Japan), is a fermentation product of soy extract and basidiomycetes mycillae that is enriched in biologically active aglycone isoflavones. This study analyzes GCP in vitro and in vivo for potential utility as a prostate cancer chemopreventative agent.

EXPERIMENTAL DESIGN

Androgen-sensitive LNCaP and androgen-independent PC-3 cells were grown with various concentrations of GCP. In vitro cell growth was analyzed by the WST-1 assay, and apoptosis was assessed by fluorescence-activated cell sorting and detection of poly(ADP-ribose) polymerase cleavage using Western blot techniques. Effects of GCP on expression of cell cycle-regulatory proteins p53 (LNCaP only), p21, and p27 and the protein kinase Akt were considered using Western blot techniques. An in vivo LNCaP xenograft model was used to study the effects of a 2% GCP-supplemented diet on tumor growth in comparison with a control diet.

RESULTS

GCP significantly suppressed LNCaP and PC-3 cell growth over 72 h (89% and 78% in LNCaP and PC-3, respectively, at 10 microg/ml; P < 0.0001). This reduction was associated with apoptosis in LNCaP cells, but not in PC-3 cells. GCP induced p27 and p53 (LNCaP only) protein expression within 6 h and suppressed phosphorylated Akt in both cell lines. The 2% GCP-supplemented diet significantly slowed LNCaP tumor growth, increasing apoptosis (P < 0.001), and decreasing proliferation (P < 0.001) over 4 weeks.

CONCLUSIONS

GCP has potent growth-inhibitory effects against prostate cancer cell lines in vitro and in vivo. These data suggest GCP has potential as an effective chemopreventive agent against prostate cancer cell growth.

The cytoplasmic domain of Xenopus NF-protocadherin interacts with TAF1/set

Protocadherins are members of the cadherin superfamily of cell adhesion molecules proposed to play important roles in early development, but whose mechanisms of action are largely unknown. We examined the function of NF-protocadherin (NFPC), a novel cell adhesion molecule essential for the histogenesis of the embryonic ectoderm in Xenopus, and demonstrate that the cellular protein TAF1, previously identified as a histone-associated protein, binds the NFPC cytoplasmic domain. NFPC and TAF1 coprecipitate from embryo extracts when ectopically expressed, and TAF1 can rescue the ectodermal disruptions caused by a dominant-negative NFPC construct lacking the extracellular domain. Furthermore, disruptions in either NFPC or TAF1 expression, using NFPC- or TAF1-specific antisense morpholinos, result in essentially identical ectodermal defects. These results indicate a role for TAF1 in the differentiation of the embryonic ectoderm, as a cytosolic cofactor of NFPC.