Androgen receptor signaling pathway in prostate cancer

Eturauhassyövän kasvun tiedetään olevan riippuvaista miessukupuolihormoneista eli androgeeneistä. Androgeenien vaikutus välittyy solussa spesifisen androgeenireseptorin (AR) välityksellä. AR puolestaan säätelee lukuisten muiden geenien ilmentymistä. AR:n ilmentymisen tiedetään myös lisääntyvän eturauhassyövän etenemisen aikana. Väitöskirjatutkimukseni tavoitteena oli selvittää miten AR:n yli-ilmentyminen vaikuttaa eturauhassyöpäsoluihin. Tätä varten kehitimme mm. solulinjamallin, joka yli-ilmensi AR:ia. Yli-ilmentyneen AR:n todettiin herkistävän syöpäsolut matalille androgeenipitoisuuksille lisäten mm. syöpäsolujen kasvua. Yli-ilmentyneen AR:n todettiin myös lisäävän huomattavasti ylössäädeltyjen geenien lukumäärää. AR:n yli-ilmentyminen aktivoi solunjakaantumista sääteleviä geenejä. Työssä löydettiin uusia AR:n kohdegeenejä, joiden tiedetään säätelevän solujakaantumista. Lisäksi löydettiin androgeenisäädeltyjä ja eturauhassyövässä ilmenemiseltään muuttuneita ns. pieniä microRNA:ta (miRNA). miRNA:ten tiedetään säätelevän lukuisia proteiineja koodaavia geenejä ja näin olevan mahdollisesti tärkeitä syövässä. Väitöskirja antoi merkittävää tutkimustietoa sekä AR:n yli-ilmentymisen vaikutuksesta eturauhassyöpäsolujen kasvuun että AR:n kohdegeeneistä. Tulokset antavat viitteitä mahdollisista uusista lääkkeiden kohteista eturauhassyövässä.The progression and growth of prostate cancer (PC) has been shown to be dependent on androgens. The standard treatment of advanced PC is androgen deprivation, which reduces the levels of testosterone in the body. Initially, the treatment inhibits tumor growth effectively, but it ultimately fails and leads to the emergence of castration-resistant PC (CRPC). Presently, no truly effective treatment for CRPC has been discovered. The androgen receptor gene (AR) is known to be altered in several ways during PC progression. Thus, AR is believed to be the one of the major contributors to the emergence of CRPC. The objective of this thesis was to identify genetic alterations, other than gene amplification, which result in the overexpression of AR during the progression of PC. Furthermore, we investigated the effects of AR overexpression on the growth of PC cells and on the transcription of protein-coding and microRNA (miRNA) genes using cell line and xenograft models as well as clinical patient samples. No novel genetic alterations were identified that could explain AR overexpression. Overexpression of AR was found to enhance the growth of PC cells and the expression of AR target genes under low androgen conditions. Overexpression of AR increased significantly the number of upregulated genes. Additionally, several novel AR target genes associated with regulation of the cell cycle and mitosis were identified. Thus, one effect of the overexpression of AR seems to be the enhancement of the cell cycle under low androgen conditions. Inhibition of these target genes significantly decreased the growth of AR overexpressing cells. Novel androgen-regulated and differentially expressed miRNAs, such as miR-18a, miR-141, miR-375 and miR-221, were also identified in the study. The exogenous overexpression of miR-141 was found to enhance the androgen-dependent growth of PC cells. At present, androgen deprivation is the standard treatment for advanced PC, and it is known that the overexpression of AR is a common event in CRPC. Thus, this thesis provides important information, especially regarding AR target genes in PC cells expressing high levels of AR

Somatic mutation analysis of MYH11 in breast and prostate cancer.

BACKGROUND: MYH11 (also known as SMMHC) encodes the smooth-muscle myosin heavy chain, which has a key role in smooth muscle contraction. Inversion at the MYH11 locus is one of the most frequent chromosomal aberrations found in acute myeloid leukemia. We have previously shown that MYH11 mutations occur in human colorectal cancer, and may also be associated with Peutz-Jeghers syndrome. The mutations ... [More

Androgen regulation of the androgen receptor coregulators

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Androgen receptor signaling pathway in prostate cancer

Eturauhassyövän kasvun tiedetään olevan riippuvaista miessukupuolihormoneista eli androgeeneistä. Androgeenien vaikutus välittyy solussa spesifisen androgeenireseptorin (AR) välityksellä. AR puolestaan säätelee lukuisten muiden geenien ilmentymistä. AR:n ilmentymisen tiedetään myös lisääntyvän eturauhassyövän etenemisen aikana. Väitöskirjatutkimukseni tavoitteena oli selvittää miten AR:n yli-ilmentyminen vaikuttaa eturauhassyöpäsoluihin. Tätä varten kehitimme mm. solulinjamallin, joka yli-ilmensi AR:ia. Yli-ilmentyneen AR:n todettiin herkistävän syöpäsolut matalille androgeenipitoisuuksille lisäten mm. syöpäsolujen kasvua. Yli-ilmentyneen AR:n todettiin myös lisäävän huomattavasti ylössäädeltyjen geenien lukumäärää. AR:n yli-ilmentyminen aktivoi solunjakaantumista sääteleviä geenejä. Työssä löydettiin uusia AR:n kohdegeenejä, joiden tiedetään säätelevän solujakaantumista. Lisäksi löydettiin androgeenisäädeltyjä ja eturauhassyövässä ilmenemiseltään muuttuneita ns. pieniä microRNA:ta (miRNA). miRNA:ten tiedetään säätelevän lukuisia proteiineja koodaavia geenejä ja näin olevan mahdollisesti tärkeitä syövässä. Väitöskirja antoi merkittävää tutkimustietoa sekä AR:n yli-ilmentymisen vaikutuksesta eturauhassyöpäsolujen kasvuun että AR:n kohdegeeneistä. Tulokset antavat viitteitä mahdollisista uusista lääkkeiden kohteista eturauhassyövässä.The progression and growth of prostate cancer (PC) has been shown to be dependent on androgens. The standard treatment of advanced PC is androgen deprivation, which reduces the levels of testosterone in the body. Initially, the treatment inhibits tumor growth effectively, but it ultimately fails and leads to the emergence of castration-resistant PC (CRPC). Presently, no truly effective treatment for CRPC has been discovered. The androgen receptor gene (AR) is known to be altered in several ways during PC progression. Thus, AR is believed to be the one of the major contributors to the emergence of CRPC. The objective of this thesis was to identify genetic alterations, other than gene amplification, which result in the overexpression of AR during the progression of PC. Furthermore, we investigated the effects of AR overexpression on the growth of PC cells and on the transcription of protein-coding and microRNA (miRNA) genes using cell line and xenograft models as well as clinical patient samples. No novel genetic alterations were identified that could explain AR overexpression. Overexpression of AR was found to enhance the growth of PC cells and the expression of AR target genes under low androgen conditions. Overexpression of AR increased significantly the number of upregulated genes. Additionally, several novel AR target genes associated with regulation of the cell cycle and mitosis were identified. Thus, one effect of the overexpression of AR seems to be the enhancement of the cell cycle under low androgen conditions. Inhibition of these target genes significantly decreased the growth of AR overexpressing cells. Novel androgen-regulated and differentially expressed miRNAs, such as miR-18a, miR-141, miR-375 and miR-221, were also identified in the study. The exogenous overexpression of miR-141 was found to enhance the androgen-dependent growth of PC cells. At present, androgen deprivation is the standard treatment for advanced PC, and it is known that the overexpression of AR is a common event in CRPC. Thus, this thesis provides important information, especially regarding AR target genes in PC cells expressing high levels of AR

Androgen regulation of micro-RNAs in prostate cancer

BACKGROUND. Androgens play a critical role in the growth of both androgen dependent and castration-resistant prostate cancer (CRPC). Only a few micro-RNAs (miRNAs) have been suggested to be androgen regulated. We aim to identify androgen regulated miRNAs. METHODS. We utilized LNCaP derived model, we have established, and which over-expresses the androgen receptor (AR), the VCaP cell line, and 13 intact-castrated prostate cancer (PC) xenograft pairs, as well as clinical specimens of untreated (PC) and CRPC. The expression of miRNAs was analyzed by microarrays and quantitative RT-PCR (Q-RT-PCR). Transfection of pre-miR-141 and anti-miR-141 was also used. RESULTS. Seventeen miRNAs were > 1.5-fold up-or downregulated upon dihydrotestosterone (DHT) treatment in the cell lines, and 42 after castration in the AR-positive xenografts. Only four miRNAs (miR-10a, miR-141, miR-150*, and miR-1225-5p) showed similar androgen regulation in both cell lines and xenografts. Of those, miR-141 was found to be expressed more in PC and CRPC compared to benign prostate hyperplasia. Additionally, the overexpression of miR-141 enhanced growth of parental LNCaP cells while inhibition of miR-141 by anti-miR-141 suppressed the growth of the LNCaP subline overexpressing AR. CONCLUSIONS. Only a few miRNAs were found to be androgen-regulated in both cell lines and xenografts models. Of those, the expression of miR-141 was upregulated in cancer. The ectopic overexpression of miR-141 increased growth of LNCaP cell suggesting it may contribute to the progression of PC. Prostate 71: 604-614, 2011. (C) 2010 Wiley-Liss, Inc

The nucleotide sequence of the Escherichia coli K12 nusB (groNB) gene.

The nusB (groNB) gene product of Escherichia coli plays a pivotal role in allowing bacteriophage lambda N protein to function as an antiterminator of mRNA transcription and in modulating host gene expression. In addition it is essential for bacterial viability since mutations in it result in a cold-sensitivity phenotype for growth. We have previously cloned the nusB gene and shown it to code for a 14,500-Mr protein. Here we present the primary DNA sequence of the nusB gene. From the sequence we deduce that it codes for a slightly basic protein (21 basic as opposed to 20 acidic amino acids) composed of 139 amino acids with a cumulative 15,689-Mr. The predicted N-terminal amino acid sequence as well as the overall amino acid composition agrees well with that of the purified protein

Constitutively active androgen receptor splice variants AR-V3, AR-V7 and AR-V9 are co-expressed in castration-resistant prostate cancer metastases

Background: A significant subset of prostate cancer (PC) patients with a castration-resistant form of the disease (CRPC) show primary resistance to androgen receptor (AR)-targeting drugs developed against CRPC. As one explanation could be the expression of constitutively active androgen receptor splice variants (AR-Vs), our current objectives were to study AR-Vs and other AR aberrations to better understand the emergence of CRPC. Methods: We analysed specimens from different stages of prostate cancer by next-generation sequencing and immunohistochemistry. Results: AR mutations and copy number variations were detected only in CRPC specimens. Genomic structural rearrangements of AR were observed in 5/30 metastatic CRPC patients, but they were not associated with expression of previously known AR-Vs. The predominant AR-Vs detected were AR-V3, AR-V7 and AR-V9, with the expression levels being significantly higher in CRPC cases compared to prostatectomy samples. Out of 25 CRPC metastases that expressed any AR variant, 17 cases harboured expression of all three of these AR-Vs. AR-V7 protein expression was highly heterogeneous and higher in CRPC compared to hormone-naïve tumours. Conclusions: AR-V3, AR-V7 and AR-V9 are co-expressed in CRPC metastases highlighting the fact that inhibiting AR function via regions common to all AR-Vs is likely to provide additional benefit to patients with CRPC