Identification of PDZK4, a novel human gene with PDZ domains, that is upregulated in synovial sarcomas

Inflammatory and Proliferative Pathway Activation in Human Esophageal Myofibroblasts Treated with Acidic Bile Salts

Subepithelial human esophageal myofibroblasts (HEMFs) in gastroesophageal reflux disease (GERD) are exposed to luminal contents via impaired squamous epithelium barrier integrity. The supernatant of HEMFs treated with acidic bile salts reflective of in vivo reflux increases squamous epithelial thickness. We aimed to identify the involved mechanisms using an unbiased approach. Acidic-bile-salt-treated primary HEMF cultures (n = 4) were submitted for RNA-Seq and analyzed with Partek Flow followed by Ingenuity Pathway Analysis (IPA). A total of 1165 molecules (579 downregulated, 586 upregulated) were differentially expressed, with most top regulated molecules either extracellular or in the plasma membrane. Increases in HEMF CXCL-8, IL-6, AREG, and EREG mRNA, and protein secretion were confirmed. Top identified canonical pathways were agranulocyte and granulocyte adhesion and diapedesis, PI3K/AKT signaling, CCR5 signaling in macrophages, and the STAT3 pathway. Top diseases and biological functions were cellular growth and development, hematopoiesis, immune cell trafficking, and cell-mediated response. The targets of the top upstream regulator ErbB2 included CXCL-8, IL-6, and AREG and the inhibition of CXCL-8 in the HEMF supernatant decreased squamous epithelial proliferation. Our work shows an inflammatory/immune cell and proliferative pathways activation in HEMFs in the GERD environment and identifies CXCL-8 as a HEMF-derived chemokine with paracrine proliferative effects on squamous epithelium.

Genomic Instability of Mutation-Derived Gene Prognostic Signatures for Hepatocellular Carcinoma

Hepatocellular carcinoma (HCC) is one of the major cancer-related deaths worldwide. Genomic instability is correlated with the prognosis of cancers. A biomarker associated with genomic instability might be effective to predict the prognosis of HCC. In the present study, data of HCC patients from The Cancer Genome Atlas (TCGA) and International Cancer Genome Consortium (ICGC) databases were used. A total of 370 HCC patients from the TCGA database were randomly classified into a training set and a test set. A prognostic signature of the training set based on nine overall survival (OS)–related genomic instability–derived genes (SLCO2A1, RPS6KA2, EPHB6, SLC2A5, PDZD4, CST2, MARVELD1, MAGEA6, and SEMA6A) was constructed, which was validated in the test and TCGA and ICGC sets. This prognostic signature showed more accurate prediction for prognosis of HCC compared with tumor grade, pathological stage, and four published signatures. Cox multivariate analysis revealed that the risk score could be an independent prognostic factor of HCC. A nomogram that combines pathological stage and risk score performed well compared with an ideal model. Ultimately, paired differential expression profiles of genes in the prognostic signature were validated at mRNA and protein level using HCC and paratumor tissues obtained from our institute. Taken together, we constructed and validated a genomic instability–derived gene prognostic signature, which can help to predict the OS of HCC and help us to explore the potential therapeutic targets of HCC.

A Ten-N6-Methyladenosine (m6A)-Modified Gene Signature Based on a Risk Score System Predicts Patient Prognosis in Rectum Adenocarcinoma

OBJECTIVES

The study aims to analyze the expression of N6-methyladenosine (m6A)-modified genes in rectum adenocarcinoma (READ) and identify reliable prognostic biomarkers to predict the prognosis of READ.

MATERIALS AND METHODS

RNA sequence data of READ and corresponding clinical survival data were obtained from The Cancer Genome Atlas (TCGA) database. N6-methyladenosine (m6A)-modified genes in READ were downloaded from the "m6Avar" database. Differentially expressed m6A-modified genes in READ stratified by different clinicopathological characteristics were identified using the "limma" package in R. Protein-protein interaction (PPI) network and co-expression analysis of differentially expressed genes (DEGs) were performed using "STRING" and Cytoscape, respectively. Principal component analysis (PCA) was done using R. In addition, Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways were used to functionally annotate the differentially expressed genes in different subgroups. Univariate Cox regression analyses were conducted to identify the powerful independent prognostic factors in READ associated with overall survival (OS). A robust likelihood-based survival model was built using the "rbsurv" package to screen for survival-associated signature genes. The Support Vector Machine (SVM) was used to predict the prognosis of READ through the risk score of survival-associated signature genes. Correlation analysis were carried out using GraphPad prism 8.

RESULTS

We screened 974 differentially expressed m6A-modified genes among four types of READ samples. Two READ subgroups (group 1 and group 2) were identified by K means clustering according to the expression of DEGs. The two subgroups were significantly different in overall survival and pathological stages. Next, 118 differentially expressed genes between the two subgroups were screened and the expression of 112 genes was found to be related to the prognosis of READ. Next, a panel of 10 survival-associated signature genes including adamtsl1, csmd2, fam13c, fam184a, klhl4, olfml2b, pdzd4, sec14l5, setbp1, tmem132b was constructed. The signature performed very well for prognosis prediction, time-dependent receiver-operating characteristic (ROC) analysis displaying an area under the curve (AUC) of 0.863, 0.8721, and 0.8752 for 3-year survival rate, prognostic status, and pathological stage prediction, respectively. Correlation analysis showed that the expression levels of the 10 m6A-modified genes were positively correlated with that of m6A demethylase FTO and ALKBH5.

CONCLUSION

This study identified potential m6A-modified genes that may be involved in the pathophysiology of READ and constructed a novel gene expression panel for READ risk stratification and prognosis prediction.

A Five-Gene Signature Based on Stromal/Immune Scores in the Tumor Microenvironment and Its Clinical Implications for Liver Cancer

Increasing evidence highlights the clinical significance of stromal cells and immune cells in the liver cancer microenvironment. However, reliable prognostic models have not been well established. This study aimed to develop a gene signature for liver cancer based on stromal and immune scores. Using the estimation of stromal and immune cells in malignant tumor tissues using expression data (ESTIMATE) algorithm, stromal and immune scores were estimated based on the transcriptome profile of The Cancer Genome Atlas (TCGA) liver cancer cohort. Stromal-/immune-related differentially expressed genes were identified, followed by functional enrichment analysis. The Cox regression model was used to select prognostic genes and construct a gene signature. Its predictive potential was evaluated by receiver operating characteristic (ROC). The correlation between the risk score and immune cell infiltration was analyzed using Tumor Immune Estimation Resource (TIMER). Three hundred sixty-four upregulated and 10 downregulated stromal-/immune-related genes were identified, were mainly enriched in immune-related processes and pathways. Through univariate and multivariate cox survival analysis, a five-gene risk score was constructed, composed of FABP3, HTRA3, OLFML2B, PDZD4 and SLAMF6. Patients with high score indicated a poorer prognosis than those with low risk score. The areas under the ROC curves of overall survival (OS), progression-free interval, 3-, 5-year, OS status were 0.68, 0.57, 0.72, 0.74 and 0.728, indicating its well performance on predicting patients' prognoses. Furthermore, the risk score and the five genes were significantly correlated with immune cell infiltration in the tumor microenvironment. In this study, we proposed a prognostic five-gene signature based on stromal/immune scores in the liver cancer microenvironment.

L1CAM whole gene deletion in a child with L1 syndrome

L1 syndrome is a group of overlapping, X-linked disorders caused by mutations in L1CAM. Clinical phenotypes within L1 syndrome include X-linked hydrocephalus with stenosis of the aqueduct of sylvius (HSAS); mental retardation, adducted thumbs, shuffling gait, and aphasia (MASA) syndrome; spastic paraplegia type 1; and agenesis of the corpus callosum. Over 200 mutations in L1CAM have been reported; however, only a few large gene deletions have been observed. We report on a 4-month-old male with a de novo whole gene deletion of L1CAM presenting with congenital hydrocephalus, aqueductal stenosis, and adducted thumbs. Initial failure of L1CAM gene sequencing suggested the possibility of a whole gene deletion of L1CAM. Further investigation through chromosome microarray analysis showed a 62Kb deletion encompassing the first exon of the PDZD4 gene and the entire L1CAM gene. Investigations into genotype-phenotype correlations have suggested that mutations leading to truncated or absent L1 protein cause more severe forms of L1 syndrome. Based on the presentation of the proband and other reported patients with whole gene deletions, we provide further evidence that L1CAM whole gene deletions result in L1 syndrome with a severe phenotype, deletions of PDZD4 do not cause additional manifestations, and that X-linked nephrogenic diabetes insipidus reported in a subset of patients with large L1CAM deletions results from the loss of AVPR2.

The expanding family of FERM proteins

Our understanding of the FERM (4.1/ezrin/radixin/moesin) protein family has been rapidly expanding in the last few years, with the result that many new physiological functions have been ascribed to these biochemically unique proteins. In the present review, we will discuss a number of new FRMD (FERM domain)-containing proteins that were initially discovered from genome sequencing but are now being established through biochemical and genetic studies to be involved both in normal cellular processes, but are also associated with a variety of human diseases.

Molecular evolution of the LNX gene family

Background

LNX (Ligand of Numb Protein-X) proteins typically contain an amino-terminal RING domain adjacent to either two or four PDZ domains - a domain architecture that is unique to the LNX family. LNX proteins function as E3 ubiquitin ligases and their domain organisation suggests that their ubiquitin ligase activity may be targeted to specific substrates or subcellular locations by PDZ domain-mediated interactions. Indeed, numerous interaction partners for LNX proteins have been identified, but the in vivo functions of most family members remain largely unclear.

Results

To gain insights into their function we examined the phylogenetic origins and evolution of the LNX gene family. We find that a LNX1/LNX2-like gene arose in an early metazoan lineage by gene duplication and fusion events that combined a RING domain with four PDZ domains. These PDZ domains are closely related to the four carboxy-terminal domains from multiple PDZ domain containing protein-1 (MUPP1). Duplication of the LNX1/LNX2-like gene and subsequent loss of PDZ domains appears to have generated a gene encoding a LNX3/LNX4-like protein, with just two PDZ domains. This protein has novel carboxy-terminal sequences that include a potential modular LNX3 homology domain. The two ancestral LNX genes are present in some, but not all, invertebrate lineages. They were, however, maintained in the vertebrate lineage, with further duplication events giving rise to five LNX family members in most mammals. In addition, we identify novel interactions of LNX1 and LNX2 with three known MUPP1 ligands using yeast two-hybrid asssays. This demonstrates conservation of binding specificity between LNX and MUPP1 PDZ domains.

Conclusions

The LNX gene family has an early metazoan origin with a LNX1/LNX2-like protein likely giving rise to a LNX3/LNX4-like protein through the loss of PDZ domains. The absence of LNX orthologs in some lineages indicates that LNX proteins are not essential in invertebrates. In contrast, the maintenance of both ancestral LNX genes in the vertebrate lineage suggests the acquisition of essential vertebrate specific functions. The revelation that the LNX PDZ domains are phylogenetically related to domains in MUPP1, and have common binding specificities, suggests that LNX and MUPP1 may have similarities in their cellular functions.

Tissue-specific and ubiquitous expression patterns from alternative promoters of human genes

BACKGROUND

Transcriptome diversity provides the key to cellular identity. One important contribution to expression diversity is the use of alternative promoters, which creates mRNA isoforms by expanding the choice of transcription initiation sites of a gene. The proximity of the basal promoter to the transcription initiation site enables prediction of a promoter's location based on the gene annotations. We show that annotation of alternative promoters regulating expression of transcripts with distinct first exons enables a novel methodology to quantify expression levels and tissue specificity of mRNA isoforms.

PRINCIPAL FINDINGS

The use of distinct alternative first exons in 3,296 genes was examined using exon-microarray data from 11 human tissues. Comparing two transcripts from each gene we found that the activity of alternative promoters (i.e., P1 and P2) was not correlated through tissue specificity or level of expression. Furthermore neither P1 nor P2 conferred any bias for tissue-specific or ubiquitous expression. Genes associated with specific diseases produced transcripts whose limited expression patterns were consistent with the tissue affected in disease. Notably, genes that were historically designated as tissue-specific or housekeeping had alternative isoforms that showed differential expression. Furthermore, only a small number of alternative promoters showed expression exclusive to a single tissue indicating that "tissue preference" provides a better description of promoter activity than tissue specificity. When compared to gene expression data in public databases, as few as 22% of the genes had detailed information for more than one isoform, whereas the remainder collapsed the expression patterns from individual transcripts into one profile.

CONCLUSIONS

We describe a computational pipeline that uses microarray data to assess the level of expression and breadth of tissue profiles for transcripts with distinct first exons regulated by alternative promoters. We conclude that alternative promoters provide individualized regulation that is confirmed through expression levels, tissue preference and chromatin modifications. Although the selective use of alternative promoters often goes uncharacterized in gene expression analyses, transcripts produced in this manner make unique contributions to the cell that requires further exploration.

Activation of an estrogen/estrogen receptor signaling by BIG3 through its inhibitory effect on nuclear transport of PHB2/REA in breast cancer

Breast cancer is known to be a hormone-dependent disease, and estrogens through an interaction with estrogen receptor (ER) enhance the proliferative and metastatic activity of breast tumor cells. Here we show a critical role of transactivation of BIG3, brefeldin A-inhibited guanine nucleotide-exchange protein 3, in activation of the estrogen/ER signaling in breast cancer cells. Knocking-down of BIG3 expression with small-interfering RNA (siRNA) drastically suppressed the growth of breast cancer cells. Subsequent coimmunoprecipitation and immunoblotting assays revealed an interaction of BIG3 with prohibitin 2/repressor of estrogen receptor activity (PHB2/REA). When BIG3 was absent, stimulation of estradiol caused the translocation of PHB2/REA to the nucleus, enhanced the interaction of PHB2/REA and ERalpha, and resulted in suppression of the ERalpha transcriptional activity. On the other hand, when BIG3 was present, BIG3 trapped PHB2/REA in the cytoplasm and inhibited its nuclear translocation, and caused enhancement of ERalpha transcriptional activity. Our results imply that BIG3 overexpression is one of the important mechanisms causing the activation of the estrogen/ERalpha signaling pathway in the hormone-related growth of breast cancer cells.

Involvement of elevated expression of multiple cell-cycle regulator, DTL/RAMP (denticleless/RA-regulated nuclear matrix associated protein), in the growth of breast cancer cells

To investigate the detailed molecular mechanism of mammary carcinogenesis and discover novel therapeutic targets, we previously analysed gene expression profiles of breast cancers. We here report characterization of a significant role of DTL/RAMP (denticleless/RA-regulated nuclear matrix associated protein) in mammary carcinogenesis. Semiquantitative RT-PCR and northern blot analyses confirmed upregulation of DTL/RAMP in the majority of breast cancer cases and all of breast cancer cell lines examined. Immunocytochemical and western blot analyses using anti-DTL/RAMP polyclonal antibody revealed cell-cycle-dependent localization of endogenous DTL/RAMP protein in breast cancer cells; nuclear localization was observed in cells at interphase and the protein was concentrated at the contractile ring in cytokinesis process. The expression level of DTL/RAMP protein became highest at G(1)/S phases, whereas its phosphorylation level was enhanced during mitotic phase. Treatment of breast cancer cells, T47D and HBC4, with small-interfering RNAs against DTL/RAMP effectively suppressed its expression and caused accumulation of G(2)/M cells, resulting in growth inhibition of cancer cells. We further demonstrate the in vitro phosphorylation of DTL/RAMP through an interaction with the mitotic kinase, Aurora kinase-B (AURKB). Interestingly, depletion of AURKB expression with siRNA in breast cancer cells reduced the phosphorylation of DTL/RAMP and decreased the stability of DTL/RAMP protein. These findings imply important roles of DTL/RAMP in growth of breast cancer cells and suggest that DTL/RAMP might be a promising molecular target for treatment of breast cancer.

Enhanced expression of RAD51 associating protein-1 is involved in the growth of intrahepatic cholangiocarcinoma cells

PURPOSE

Intrahepatic cholangiocarcinoma (ICC) is the second most common primary cancer in the liver, and its incidence is increasing in developed countries.

EXPERIMENTAL DESIGN

To discover novel molecular targets for the diagnosis and treatment of ICCs, we earlier analyzed expression profiles of 25 ICCs using a cDNA microarray containing 27,648 genes. In this study, we focused on the RAD51 associating protein-1 (RAD51AP1) gene because its expression was frequently elevated in our microarray data.

RESULTS

Quantitative PCR confirmed that RAD51AP1 expression was elevated in the great majority of the ICCs examined. Immunohistochemical analysis with anti-RAD51AP1 antibody further corroborated its accumulation in 14 of 23 ICC tissues (61%). Notably, suppression of RAD51AP1 by short interfering RNA resulted in growth suppression of cholangiocarcinoma cells, suggesting its involvement in the development and/or progression of ICC. Because RAD51AP1 interacts with RAD51, a molecule involved in DNA repair, we investigated whether RAD51AP1 is implicated in DNA strand breaks using gamma-irradiation. As a result, gamma-irradiation augmented RAD51AP1 protein expression and brought a focus formation in the nuclei, where accumulated RAD51AP1 colocalized with phosphorylated histone 2AX (gamma-H2AX) and RAD51. These data suggest that RAD51AP1 may play a role in cell proliferation as well as DNA repair.

CONCLUSION

Our findings may contribute to the better understanding of cholangiocarcinogenesis and open a new avenue to the development of novel therapeutic and/or diagnostic approach to this type of tumor.

Involvement of kinesin family member 2C/mitotic centromere-associated kinesin overexpression in mammary carcinogenesis

To elucidate the molecular mechanisms of mammary carcinogenesis and discover novel therapeutic targets for breast cancer, we previously carried out genome-wide expression profile analysis of 81 breast cancer cases by means of cDNA microarray coupled with laser microbeam microdissection of cancer cells. Among the dozens of transactivated genes, in the present study we focused on the functional significance of kinesin family member 2C (KIF2C)/mitotic centromere-associated kinesin (MCAK) in the growth of breast cancer cells. Northern blot and immunohistochemical analyses confirmed KIF2C/MCAK overexpression in breast cancer cells, and showed that it is expressed at undetectable levels in normal human tissues except the testis, suggesting KIF2C/MCAK to be a cancer-testis antigen. Western blot analysis using breast cancer cell lines revealed a significant increase in the endogenous KIF2C/MCAK protein level and its phosphorylation in G(2)/M phase. Treatment of breast cancer cells with small interfering RNA against KIF2C/MCAK effectively suppressed KIF2C/MCAK expression and inhibited the growth of the breast cancer cell lines T47D and HBC5. In addition, we found that KIF2C/MCAK expression was significantly suppressed by ectopic introduction of p53. These findings suggest that overexpression of KIF2C/MCAK might be involved in breast carcinogenesis and is a promising therapeutic target for breast cancers.

Molecular target therapy for synovial sarcoma

Although the specific chromosomal translocation and fusion gene SYT-SSX in synovial sarcoma (SS) has been identified, the molecular mechanism of its tumorigenesis is largely unknown. Recent gene-expression profiles of soft-tissue tumors using cDNA microarray demonstrated that SS has the distinct gene-expression pattern from other sarcomas and has a similar pattern to that of malignant peripheral nerve sheath tumors, indicating that the origin of SS is likely to be the neural crest cells. Through this analysis, several genes were found to be specifically upregulated in SS and considered to play an important role in the proliferation of SS cells. Among them, Frizzled homolog 10 was identified as a good candidate molecule for the development of novel therapies to treat SS patients.

Oncogenic role of MPHOSPH1, a cancer-testis antigen specific to human bladder cancer

To disclose the molecular mechanism of bladder cancer, the second most common genitourinary tumor, we had previously done genome-wide expression profile analysis of 26 bladder cancers by means of cDNA microarray representing 27,648 genes. Among genes that were significantly up-regulated in the majority of bladder cancers, we here report identification of M-phase phosphoprotein 1 (MPHOSPH1) as a candidate molecule for drug development for bladder cancer. Northern blot analyses using mRNAs of normal human organs and cancer cell lines indicated this molecule to be a novel cancer-testis antigen. Introduction of MPHOSPH1 into NIH3T3 cells significantly enhanced cell growth at in vitro and in vivo conditions. We subsequently found an interaction between MPHOSPH1 and protein regulator of cytokinesis 1 (PRC1), which was also up-regulated in bladder cancer cells. Immunocytochemical analysis revealed colocalization of endogenous MPHOSPH1 and PRC1 proteins in bladder cancer cells. Interestingly, knockdown of either MPHOSPH1 or PRC1 expression with specific small interfering RNAs caused a significant increase of multinuclear cells and subsequent cell death of bladder cancer cells. Our results imply that the MPHOSPH1/PRC1 complex is likely to play a crucial role in bladder carcinogenesis and that inhibition of the MPHOSPH1/PRC1 expression or their interaction should be novel therapeutic targets for bladder cancers.

Involvement of upregulation of DEPDC1 (DEP domain containing 1) in bladder carcinogenesis

In an attempt to disclose mechanisms of bladder carcinogenesis and discover novel target molecules for development of treatment, we applied a cDNA microarray to screen genes that were significantly transactivated in bladder cancer cells. Among the upregulated genes, we here focused on a novel gene, (DEPDC1) DEP domain containing 1, whose overexpression was confirmed by northern blot and immunohistochemical analyses. Immunocytochemical staining analysis detected strong staining of endogenous DEPDC1 protein in the nucleus of bladder cancer cells. Since DEPDC1 expression was hardly detectable in any of 24 normal human tissues we examined except the testis, we considered this gene-product to be a novel cancer/testis antigen. Suppression of DEPDC1 expression with small-interfering RNA significantly inhibited growth of bladder cancer cells. Taken together, these findings suggest that DEPDC1 might play an essential role in the growth of bladder cancer cells, and would be a promising molecular-target for novel therapeutic drugs or cancer peptide-vaccine to bladder cancers.

Adult human sarcomas. II. Medical oncology

Human sarcoma cells can be killed by radio- and chemotherapy, but tumor cells acquiring resistance frequently kill the patient. A keen understanding of the intracellular course of oncogenic cascades leads to the discovery of small molecular inhibitors of the involved phosphorylated kinases. Targeted therapy complements chemotherapy. Oncogene silencing is feasible by small interfering RNA. The restoration of some of the mutated or deleted tumor-suppressor genes (p53, Rb, PTEN, hSNF, INK/ARF and WT) by demethylation or reacetylation of their histones has been accomplished. Genetically engineered or naturally oncolytic viruses selectively lyse tumors and leave healthy tissues intact. Adeno- or retroviral vectors deliver genes of immunological costimulators, tumor antigens, chemo- or cytokines and/or tumor-suppressor proteins into tumor (sarcoma) cells. Suicide gene delivery results in apoptosis induction. Genes of enzymes that target prodrugs as their substrates render tumor cells highly susceptible to chemotherapy, with the prodrug to be targeted intracellularly. It will be combinations of sophisticated surgical removal of the nonencapsulated and locally invasive primary sarcomas, advanced forms of radiotherapy to the involved sites and immunotherapy with sarcoma vaccines that will cure primary sarcomas. Adoptive immunotherapy with immune lymphocytes will be operational in metastatic disease only when populations of regulatory T cells are controlled. Targeted therapy with small molecular inhibitors of oncogene cascades, the driving forces of sarcoma cells, alteration of the tumor stroma from a supportive to a tumor-hostile environment, reactivation or replacement of wild-type tumor-suppressor genes, and radio-chemotherapy (with much reduced toxicity) will eventually accomplish the cure of metastatic sarcomas.

Adult human sarcomas. I. Basic science

When connective tissue undergoes malignant transformation, glioblastomas and sarcomas arise. However, the ancient biochemical mechanisms, which are now operational in sarcomas distorted by mutations and gene fusions in misaligned chromosomes, were originally acquired by those cells that emerged during the Cambrian explosion. Preserved throughout evolution up to the genus Homo, these mechanisms dictate the apoptosis- and senescence-resistant immortality of malignant cells. A 'retroviral paradox' distinguishes human sarcomas from those of the animal world. In contrast to the retrovirally induced sarcomatous transformation of animal (avian, murine, feline and simian) cells, human sarcomas have so far failed to yield a causative retroviral isolate. However, the proto-oncogenes/oncogenes transduced from their host cells by retroviruses of animals are the same that are active in human sarcomas. Since the encoded oncoproteins arise after birth, they are recognized frequently by the immune system of the host. Immune lymphocytes that kill autologous sarcoma cells in vitro commonly fail to do so in vivo. Sarcoma vaccines generate immune T- and natural killer cell reactions; even when vaccinated patients do not show a clinical response, their tumors become more sensitive to chemotherapy. The aim of this review is to lay a solid molecular biological foundation for the conclusion that targeting the sarcoma oncogenes will result in regression of the disease.

Elevated expression of protein regulator of cytokinesis 1, involved in the growth of breast cancer cells

To elucidate molecular mechanisms of mammary carcinogenesis and discover novel therapeutic targets for breast cancer, we previously carried out a genome-wide expression profile analysis of 81 breast cancer cases by means of a combination of cDNA microarray and laser microbeam microdissection. Among the upregulated genes, we focused on the functional significance of protein regulator of cytokinesis 1 (PRC1) in the development of breast cancer. Western blot analysis using breast cancer cell lines revealed a significant increase in endogenous PRC1 levels in G(2)/M phase. Treatment of breast cancer cells with small interfering RNA against PRC1 effectively suppressed its expression and inhibited the growth of breast cancer cell lines T47D and HBC5. Furthermore, we found an interaction between PRC1 and kinesin family member 2C/mitotic centromere-associated kinesin (KIF2C/MCAK) by coimmunoprecipitation and immunoblotting using COS-7 cells, in which these molecules were introduced exogenously. These findings suggest the involvement of a PRC1-KIF2C/MCAK complex in breast tumorigenesis, and this complex should be a promising target for the development of novel treatments for breast cancer.

PDZ-binding kinase/T-LAK cell-originated protein kinase, a putative cancer/testis antigen with an oncogenic activity in breast cancer

Breast cancer is one of the most common cancers among women. To discover molecular targets that are applicable for development of novel breast cancer therapy, we previously did genome-wide expression profile analysis of 81 breast cancers and found dozens of genes that were highly and commonly up-regulated in breast cancer cells. Among them, we here focused on one gene that encodes PDZ-binding kinase/T-LAK cell-originated protein kinase (PBK/TOPK), including a kinase domain. Northern blot analyses using mRNAs of normal human organs, breast cancer tissues, and cancer cell lines indicated this molecule to be a novel cancer/testis antigen. Reduction of PBK/TOPK expression by small interfering RNA resulted in significant suppression of cell growth probably due to dysfunction in the cytokinetic process. Immunocytochemical analysis with anti-PBK/TOPK antibody implicated a critical role of PBK/TOPK in an early step of mitosis. PBK/TOPK could phosphorylate histone H3 at Ser10 in vitro and in vivo, and mediated its growth-promoting effect through histone H3 modification. Because PBK/TOPK is the cancer/testis antigen and its kinase function is likely to be related to its oncogenic activity, we suggest PBK/TOPK to be a promising molecular target for breast cancer therapy.

Diagnosis and Management of Synovial Sarcoma

Synovial sarcoma is a unique tumor with substantial promise for biologically targeted therapy. Although it demonstrates moderate chemosensitivity, with approximately 50% response rates to ifosfamide- and doxorubicin-containing regimens, it has a diagnostic translocation and a potentially informative chimeric protein product. Although surgical management remains the cornerstone to effect local control, therapeutic advancements are unlikely to occur by continuing to include advanced cases of synovial sarcomas in trials with other soft tissue sarcomas. Rather, attention should be turned toward prospective molecular targets and development of novel agents to exploit them. Research should be directed at understanding the fusion protein of the X,18 translocation and further validating the role of overexpressed proteins in synovial sarcoma. Meanwhile, carefully designed clinical trials of these agents, with translational correlates, will provide in vivo data to complement the preclinical experience.

Biology of SNU cell lines

SNU (Seoul National University) cell lines have been established from Korean cancer patients since 1982. Of these 109 cell lines have been characterized and reported, i.e., 17 colorectal carcinoma, 12 hepatocellular carcinoma, 11 gastric carcinoma, 12 uterine cervical carcinoma, 17 B-lymphoblastoid cell lines derived from cancer patients, 5 ovarian carcinoma, 3 malignant mixed Mllerian tumor, 6 laryngeal squamous cell carcinoma, 7 renal cell carcinoma, 9 brain tumor, 6 biliary tract, and 4 pancreatic carcinoma cell lines. These SNU cell lines have been distributed to biomedical researchers domestic and worldwide through the KCLB (Korean Cell Line Bank), and have proven to be of value in various scientific research fields. The characteristics of these cell lines have been reported in over 180 international journals by our laboratory and by many other researchers from 1987. In this paper, the cellular and molecular characteristics of SNU human cancer cell lines are summarized according to their genetic and epigenetic alterations and functional analysis.

Oncogenic role of NALP7 in testicular seminomas

To isolate novel molecular targets for treatment of testicular germ cell tumor (TGCT), we performed genome-wide expression profile analysis of testicular seminomas using a cDNA microarray. We here report identification of NACHT, leucine-rich repeat and PYD containing 7 (NALP7 ), that was significantly transactivated in testicular seminomas. Subsequent semi-quantitative RT-PCR and northern blot analyses confirmed an approximately 3.3-kb transcript that was expressed exclusively in testis, although the expression level of this gene in normal testis was much lower than in tumor cells, suggesting an important role of this gene in germ-cell proliferation. Immunohistochemical analysis using anti-NALP7 polyclonal antibody detected the endogenous NALP7 protein in the cytoplasm of embryonal carcinoma cells and testicular seminoma tissues. Transfection of small interfering RNA (siRNA) for NALP7 significantly reduced the NALP7 expression and resulted in growth suppression of testicular germ-cell tumors. These findings imply that NALP7 may play a crucial role in cell proliferation, as well as testicular tumorigenesis, and it appears to be a promising candidate for development of targeted therapy for TGCTs.