HN1 is a novel dedifferentiation factor involved in regulating the cell cycle and microtubules in SH-SY5Y neuroblastoma cells.

Hematological and neurological expressed 1 (HN1), encoding a small protein, has been recently explored in different cancers owing to its higher expression in tumor samples as compared to adjacent normal. It was discovered and subsequently named because of its higher expression in hematological and neurological tissues in developing mice. Following discovery, it was considered a neuronal regeneration or dedifferentiation-related gene. However, since then, it has not been characterized in neuroblastoma or differentiated neurons. SH-SY5Y cell line presents a unique model of neuroblastoma often utilized in neurobiology research. In this study, first, we employed bioinformatics analysis along with in vitro evaluation using normal and retinoic acid (RA)-differentiated SH-SY5Y cells to determine the responses of HN1 and its function. The analysis revealed that HN1 expression is higher in neuroblastoma and lower in differentiated neurons and Parkinson's disease as compared to appropriate controls. Since HN1 coexpression network in neuroblastoma is found to be enriched in cell-cycle-related pathways, we have shown that HN1 expression increases in S-phase and remains lower in the rest of the cell cycle phases. Moreover, HN1 expression is also correlated with the microtubule stability in SH-SY5Y cells, which was investigated with nocodazole and taxol treatments. HN1 overexpression increased the ratio of S-type cells (undifferentiated), indicating that it acts as a dedifferentiating factor in neuroblastoma cells. Moreover, cell cycle dynamics also changed upon HN1 overexpression with alternating effects on SH-SY5Y and RA-differentiated (N-type) cells. Therefore, HN1 is a potential cell cycle regulatory element in the development of neuroblastoma or dedifferentiation of neurons, which requires further studies to decipher its mechanistic role.

Synthesis and Topoisomerase I inhibitory properties of klavuzon derivatives.

Klavuzon is a naphthalen-1-yl substituted α,ß-unsaturated δ-lactone derivative, and is one of the anti-proliferative members of this class of compounds. Asymmetric and racemic syntheses of novel α,ß-unsaturated δ-lactone derivatives are important to investigate their potential for the treatment of cancer. In this study, asymmetric and racemic syntheses of heteroatom-substituted klavuzon derivatives are reported. The syntheses were completed by a well-known three-step procedure. Anti-proliferative activity of seven novel racemic klavuzon derivatives were reported against MCF-7, PC3, HCT116 p53+/+ and HCT116 p53-/- cancer cell lines. Topoisomerase I inhibitory properties of 5,6-dihydro-2H-pyran-2-one derivatives were also studied.

HN1 negatively influences the ß-catenin/E-cadherin interaction, and contributes to migration in prostate cells.

Previously, it has been reported that HN1 is involved in cytoplasmic retention and degradation of androgen receptor in an AKT dependent manner. As HN1 is a hormone inducible gene, and has been shown that it is upregulated in various cancers, we studied the importance of HN1 function in ß-catenin signaling in prostate cancer cell line, PC-3 and mammary cancer cell line MDA-MB231. Here, we demonstrated that HN1 physically associates with GSK3ß/ß-catenin destruction complex and abundantly localizes to cytoplasm, especially when the GSK3ß is phosphorylated on S9 residue. Further, ectopic HN1 expression results an increase in the ß-catenin degradation leading to loss of E-cadherin interaction, concurrently contributing to actin re-organization, colony formation and migration in cancer cell lines. Thus, we report that HN1 is an essential factor for ß-catenin turnover and signaling, augments cell growth and migration in prostate cancer cells.

DNA damage response (DDR) via NKX3.1 expression in prostate cells.

It has been reported that NKX3.1 an androgen-regulated homeobox gene restricted to prostate and testicular tissues, encodes a homeobox protein, which transcriptionally regulates oxidative damage responses and enhances topoisomerase I re-ligation by a direct interaction with the ATM protein in prostate cells. In this study, we aimed to investigate the role of NKX3.1 in DNA double-strand break (DSB) repair. We demonstrate that the DNA damage induced by CPT-11 (irinotecan, a topo I inhibitor), doxorubicin (a topo II inhibitor), and H2O2 (a mediator of oxidative damage), but not by etoposide (another topo II inhibitor), is negatively influenced by NKX3.1 expression. We also examined γH2AX((S139)) foci formation and observed that the overexpression of NKX3.1 resulted a remarkable decrease in the formation of γH2AX((S139)) foci. Intriguingly, we observed in NKX3.1 silencing studies that the depletion of NKX3.1 correlated with a significant decrease in the levels of p-ATM((S1981)) and γH2AX((S139)). The data imply that the DNA damage response (DDR) can be altered, perhaps via a decrease in the topoisomerase I re-ligation function; this is consistent with the physical association of NKX3.1 with DDR mediators upon treatment of both PC-3 and LNCaP cells with CPT-11. Furthermore, the depletion of NKX3.1 resulted in a G1/S progression via the facilitation of an increase in E2F stabilization concurrent with the suppressed DDR. Thus, the topoisomerase I inhibitor-mediated DNA damage enhanced the physical association of NKX3.1 with γH2AX((S139)) on the chromatin in LNCaP cells, whereas NKX3.1 in the soluble fraction was associated with p-ATM((S1981)) and RAD50 in these cells. Overall, the data suggest that androgens and NKX3.1 expression regulate the progression of the cell cycle and concurrently activate the DDR. Therefore, androgen withdrawal may augment the development of an error-prone phenotype and, subsequently, the loss of DNA damage control during prostate cancer progression.

Cytotoxic naphthoquinones from Alkanna cappadocica ( perpendicular).

In a continuing program to discover new anticancer agents from plants, especially naphthoquinones from the Alkanna genus, Alkanna cappadocica was investigated. Bioassay-guided fractionation of a dichloromethane/methanol (1:1) extract of the roots led to the isolation of four new and four known naphthoquinones. The known compounds are 11-deoxyalkannin (1), beta,beta-dimethylacrylalkannin (2), 11-O-acetylalkannin (3), and alkannin (4). The new compounds 5-O-methyl-11-deoxyalkannin (5), 8-O-methyl-11-deoxyalkannin (6), 5-O-methyl-11-O-acetylalkannin (7), and 5-O-methyl-beta,beta-dimethylacrylalkannin (8) were characterized by spectroscopic analyses (LC-ESIMS, 1D and 2D NMR). Cytotoxicity of the isolated compounds was evaluated versus 12 human cancer cell lines, HT-29, MDA-MB-231, PC-3, AU565, Hep G2, LNCaP, MCF7, HeLa, SK-BR-3, DU 145, Saos-2, and Hep 3B together with two normal cell lines, VERO and 3T3, by using the MTT assay. Compound 7 showed remarkable cytotoxicity with IC(50) values between 0.09 and 14.07 muM. It was more potent than the other compounds in six out of 12 cancer cell lines and the positive controls doxorubicin and etoposide. The mono-O-methylated alkannin derivatives and their cytotoxicities are reported for the first time.

Determination of naphthazarin derivatives in endemic Turkish Alkanna species by reversed phase high performance liquid chromatography.

The quantification of free and total alkannins in 13 endemic Anatolian Alkanna species is described for the first time. Extraction of the samples was performed by sonication with hexane, followed by hydrolysis in 1 N NaOH. For analysis, a new HPLC method, utilizing reversed phase material (Synergi Max RP), was developed and successfully validated. The obtained data confirmed that the assay is sensitive (LOD of 13 ng on-column for alkannin), accurate (the recovery rate was 92.3%) and precise (RSD

Molecular cloning and characterization of STAMP2, an androgen-regulated six transmembrane protein that is overexpressed in prostate cancer.

We have identified a novel gene, six transmembrane protein of prostate 2 (STAMP2), named for its high sequence similarity to the recently identified STAMP1 gene. STAMP2 displays a tissue-restricted expression with highest expression levels in placenta, lung, heart, and prostate and is predicted to code for a 459-amino acid six transmembrane protein. Using a form of STAMP2 labeled with green flourescent protein (GFP) in quantitative time-lapse and immunofluorescence confocal microscopy, we show that STAMP2 is primarily localized to the Golgi complex, trans-Golgi network, and the plasma membrane. STAMP2 also localizes to vesicular-tubular structures in the cytosol and colocalizes with the Early Endosome Antigen1 (EEA1) suggesting that it may be involved in the secretory/endocytic pathways. STAMP2 expression is exquisitely androgen regulated in the androgen-sensitive, androgen receptor-positive prostate cancer cell line LNCaP, but not in androgen receptor-negative prostate cancer cell lines PC-3 and DU145. Analysis of STAMP2 expression in matched normal and tumor samples microdissected from prostate cancer specimens indicates that STAMP2 is overexpressed in prostate cancer cells compared with normal prostate epithelial cells. Furthermore, ectopic expression of STAMP2 in prostate cancer cells significantly increases cell growth and colony formation suggesting that STAMP2 may have a role in cell proliferation. Taken together, these data suggest that STAMP2 may contribute to the normal biology of the prostate cell, as well as prostate cancer progression.

Identification of promoters bound by c-Jun/ATF2 during rapid large-scale gene activation following genotoxic stress.

The NH2-terminal Jun kinases (JNKs) function in diverse roles through phosphorylation and activation of AP-1 components including ATF2 and c-Jun. However, the genes that mediate these processes are poorly understood. A model phenotype characterized by rapid activation of Jun kinase and enhanced DNA repair following cisplatin treatment was examined using chromatin immunoprecipitation with antibodies against ATF2 and c-Jun or their phosphorylated forms and hybridization to promoter arrays. Following genotoxic stress, we identified 269 genes whose promoters are bound upon phosphorylation of ATF2 and c-Jun. Binding did not occur following treatment with transplatin or the JNK inhibitor SP600125 or JNK-specific siRNA. Of 89 known DNA repair genes represented on the array, 23 are specifically activated by cisplatin treatment within 3-6 hr. Thus, the genotoxic stress response occurs at least partly via activation of ATF2 and c-Jun, leading to large-scale coordinate gene expression dominated by genes of DNA repair.

Analysis of androgen regulated homeobox gene NKX3.1 during prostate carcinogenesis.

PURPOSE: NKX3.1 is an androgen regulated gene that is largely specific to the prostate for expression and it is predicted to encode a homeobox protein. Null alleles of NKX3.1 in mice results in impaired prostate development as well as hyperplasia and dysplasia of the prostate. In addition, the NKX3.1 gene maps to a region of high loss of heterozygosity in prostate cancer in humans, suggesting that NKX3.1 might have a direct role in prostate carcinogenesis, possibly functioning as a tumor suppressor protein. Previous studies of the levels of NKX3.1 mRNA or protein in prostate cancer specimens have resulted in conflicting findings. MATERIALS AND METHODS: To resolve this issue we assessed NKX3.1 expression by mRNA in situ analysis and immunohistochemistry on the same prostate cancer tissue arrays. RESULTS: Data showed that NKX3.1 mRNA and protein levels in prostate cancer specimens are correlated, suggesting that most regulation is at the transcriptional level. There was no correlation of NKX3.1 expression levels with tumor grade or clinical stage. In general there was a suggestion that worse clinical features at surgery were associated with lower IHC stain scores. In particular, extracapsular extension but not seminal vesicle invasion inversely correlated with NKX3.1 expression. CONCLUSIONS: Together these data suggest that NKX3.1 does not function as a typical tumor suppressor protein in prostate cancer but it may still have important regulatory roles during prostate cancer progression.

NKX3.1 expression is lost in testicular germ cell tumors.

NKX3.1 is a homeobox gene which exhibits prostate and testis specific expression. Loss of NKX3.1 expression has been implicated in prostate development and tumorigenesis, but the role of NKX3.1 in testis biology is not known. Here we show that NKX3.1 expression is dramatically down-regulated in testicular cancer of germ cell origin. Immunohistochemical analysis on a tissue microarray containing 510 testicular tissue samples indicate that NKX3.1 is expressed at high levels in normal germ cells and in carcinoma in situ, but is sharply decreased or absent in most seminomas and all embryonal carcinomas. However, NKX3.1 is expressed in a subset of the more differentiated nonseminomas. We provide evidence that these changes in NKX3.1 protein levels are mainly due to transcriptional effects. These results suggest that NKX3.1 is essential for normal testis function and that its loss of expression is highly associated with the invasive phenotype of testicular germ cell tumors.

Molecular cloning and characterization of STAMP1, a highly prostate-specific six transmembrane protein that is overexpressed in prostate cancer.

We have identified a novel gene, six transmembrane protein of prostate 1 (STAMP1), which is largely specific to prostate for expression and is predicted to code for a 490-amino acid six transmembrane protein. Using a form of STAMP1 labeled with green fluorescent protein in quantitative time-lapse and immunofluorescence confocal microscopy, we show that STAMP1 is localized to the Golgi complex, predominantly to the trans-Golgi network, and to the plasma membrane. STAMP1 also localizes to vesicular tubular structures in the cytosol and colocalizes with the early endosome antigen 1 (EEA1), suggesting that it may be involved in the secretory/endocytic pathways. STAMP1 is highly expressed in the androgen-sensitive, androgen receptor-positive prostate cancer cell line LNCaP, but not in androgen receptor-negative prostate cancer cell lines PC-3 and DU145. Furthermore, STAMP1 expression is significantly lower in the androgen-dependent human prostate xenograft CWR22 compared with the relapsed derivative CWR22R, suggesting that its expression may be deregulated during prostate cancer progression. Consistent with this notion, in situ analysis of human prostate cancer specimens indicated that STAMP1 is expressed exclusively in the epithelial cells of the prostate and its expression is significantly increased in prostate tumors compared with normal glands. Taken together, these data suggest that STAMP1 may have an important role in the normal prostate cell as well as in prostate cancer progression.