Promoter, Is a Candidate Tumor Suppressor

DDX3 is a DEAD box RNA helicase with diverse biological functions. Using colony formation assay, our results revealed that DDX3 inhibited the colony formation ability of various tumor cells, and this inhibition might be due to a reduced growth rate caused by DDX3. Additionally, we identified p21 waf1/cip1 , a cyclin-dependent kinase inhibitor, as a target gene of DDX3, and the up-regulation of p21 waf1/cip1 expression accounted for the colony-suppressing activity of DDX3. Moreover, DDX3 exerted its transactivation function on p21 waf1/cip1 promoter through an ATPase-dependent but helicase-independent mechanism, and the four Sp1 sites located within the � 123 to � 63 region, relative to the transcription start site of p21 waf1/cip1 promoter, were essential for the response to DDX3. Furthermore, DDX3 interacted and cooperated with Sp1 to up-regulate the promoter activity of p21 waf1/cip1 . To determine the relevance of DDX3 in clinical cancers, the expression profile of DDX3 in various tumors was also examined. A declined expression of DDX3 mRNA and protein was found in f58% to 73% of hepatoma specimens, which led to the reduction of p21 waf1/cip1 expression in a manner independent of p53 status. Additionally, an alteration of subcellular localization from nuclei to cytoplasm was also observed in >70% of cutaneous squamous cell carcinoma samples. Because DDX3 exhibits tumor suppressor functions, such as a growth-suppressive property and transcriptional activation of the p21 waf1/cip1 promoter, and is inactivated through down-regulation of gene expression or alteration of subcellular localization in tumor cells, all these features together suggest that DDX3 might be a candidate tumor suppressor. (Cancer Res 2006; 66(13): 6579-88)

[1]  P-C Chang,et al.  DDX3, a DEAD box RNA helicase, is deregulated in hepatitis virus-associated hepatocellular carcinoma and is involved in cell growth control , 2006, Oncogene.

[2]  A. Tsou,et al.  Integrative genomics based identification of potential human hepatocarcinogenesis-associated cell cycle regulators: RHAMM as an example. , 2005, Biochemical and biophysical research communications.

[3]  Brian J. Wilson,et al.  The DEAD box protein p68: a novel transcriptional coactivator of the p53 tumour suppressor , 2005, The EMBO journal.

[4]  T. Okamoto,et al.  RNA helicase A interacts with nuclear factor kappaB p65 and functions as a transcriptional coactivator. , 2004, European journal of biochemistry.

[5]  Nobutaka Hirokawa,et al.  Kinesin Transports RNA Isolation and Characterization of an RNA-Transporting Granule , 2004, Neuron.

[6]  Boris Zybailov,et al.  A set of consensus mammalian mediator subunits identified by multidimensional protein identification technology. , 2004, Molecular cell.

[7]  C. Chen,et al.  Diverse cellular transformation capability of overexpressed genes in human hepatocellular carcinoma. , 2004, Biochemical and biophysical research communications.

[8]  T. Hubbard,et al.  A census of human cancer genes , 2004, Nature Reviews Cancer.

[9]  P. Linder,et al.  DEAD-box proteins: the driving forces behind RNA metabolism , 2004, Nature Reviews Molecular Cell Biology.

[10]  A. De Siervi,et al.  Transcriptional Activation of p21waf1/cip1 by Alkylphospholipids , 2004, Cancer Research.

[11]  Michele Pagano,et al.  When protein destruction runs amok, malignancy is on the loose. , 2003, Cancer cell.

[12]  B. Henderson,et al.  Regulation of tumor suppressors by nuclear-cytoplasmic shuttling. , 2003, Experimental cell research.

[13]  Frederick Y. Wu,et al.  CCAAT/Enhancer Binding Protein α Interacts with ZTA and Mediates ZTA-Induced p21CIP-1 Accumulation and G1 Cell Cycle Arrest during the Epstein-Barr Virus Lytic Cycle , 2003, Journal of Virology.

[14]  D. Coppola,et al.  Loss of the cell cycle inhibitors p21Cip1 and p27Kip1 enhances tumorigenesis in knockout mouse models , 2002, Oncogene.

[15]  A. Moustakas,et al.  The role of Sp1 family members, the proximal GC-rich motifs, and the upstream enhancer region in the regulation of the human cell cycle inhibitor p21WAF-1/Cip1 gene promoter. , 2002, Biochemistry.

[16]  Steven P. Gygi,et al.  Comprehensive proteomic analysis of the human spliceosome , 2002, Nature.

[17]  M. Feitelson,et al.  Genetic mechanisms of hepatocarcinogenesis , 2002, Oncogene.

[18]  E. Olson,et al.  Suppression of proliferation and cardiomyocyte hypertrophy by CHAMP, a cardiac-specific RNA helicase , 2002, Proceedings of the National Academy of Sciences of the United States of America.

[19]  S. Friedman,et al.  KLF6, a Candidate Tumor Suppressor Gene Mutated in Prostate Cancer , 2001, Science.

[20]  M. Serrano,et al.  Tumor susceptibility of p21(Waf1/Cip1)-deficient mice. , 2001, Cancer research.

[21]  A. Moustakas,et al.  Sp1 Plays a Critical Role in the Transcriptional Activation of the Human Cyclin-dependent Kinase Inhibitor p21 WAF1/Cip1 Gene by the p53 Tumor Suppressor Protein* , 2001, The Journal of Biological Chemistry.

[22]  N. Tanner,et al.  DExD/H box RNA helicases: from generic motors to specific dissociation functions. , 2001, Molecular cell.

[23]  M. Hagiwara,et al.  Dual Roles of RNA Helicase A in CREB-Dependent Transcription , 2001, Molecular and Cellular Biology.

[24]  A. Gartel,et al.  Myc represses the p21(WAF1/CIP1) promoter and interacts with Sp1/Sp3 , 2001, Proceedings of the National Academy of Sciences of the United States of America.

[25]  S. Baylin,et al.  Sequence-specific DNA Binding Activity of RNA Helicase A to thep16INK4a Promoter* , 2001, The Journal of Biological Chemistry.

[26]  T. Sakai,et al.  Activation of the p21WAF1/CIP1 promoter independent of p53 by the histone deacetylase inhibitor suberoylanilide hydroxamic acid (SAHA) through the Sp1 sites , 2000, Oncogene.

[27]  A. Gartel,et al.  Sp1 and Sp3 activate p21 (WAF1/CIP1) gene transcription in the Caco-2 colon adenocarcinoma cell line , 2000, Oncogene.

[28]  A. Moustakas,et al.  Role of Smad Proteins and Transcription Factor Sp1 in p21Waf1/Cip1 Regulation by Transforming Growth Factor-β* , 2000, The Journal of Biological Chemistry.

[29]  G. Dotto,et al.  p21(WAF1/Cip1): more than a break to the cell cycle? , 2000, Biochimica et biophysica acta.

[30]  Y. I. Lee,et al.  Hepatitis B virus-X protein upregulates the expression of p21wafl/cipl and prolongs G1→S transition via a p53-independent pathway in human hepatoma cells , 2000, Oncogene.

[31]  G. Jenster,et al.  Androgen induction of cyclin-dependent kinase inhibitor p21 gene: role of androgen receptor and transcription factor Sp1 complex. , 2000, Molecular endocrinology.

[32]  T. Tsai,et al.  Evidence that mutational activation of the ras genes may not be involved in aflatoxin B1–induced human hepatocarcinogenesis, based on sequence analysis of the ras and p53 genes , 1999, Molecular carcinogenesis.

[33]  G. Dotto,et al.  p21(WAF1/Cip1) functions as a suppressor of malignant skin tumor formation and a determinant of keratinocyte stem-cell potential. , 1999, Proceedings of the National Academy of Sciences of the United States of America.

[34]  D. Metzger,et al.  Purification and Identification of p68 RNA Helicase Acting as a Transcriptional Coactivator Specific for the Activation Function 1 of Human Estrogen Receptor α , 1999, Molecular and Cellular Biology.

[35]  James M. Roberts,et al.  CDK inhibitors: positive and negative regulators of G1-phase progression. , 1999, Genes & development.

[36]  H. Worman,et al.  Hepatitis C Virus Core Protein Binds to a DEAD Box RNA Helicase* , 1999, The Journal of Biological Chemistry.

[37]  A. Owsianka,et al.  Hepatitis C virus core protein interacts with a human DEAD box protein DDX3. , 1999, Virology.

[38]  Chi-Hung Lin,et al.  Hepatitis C Virus Core Protein Interacts with Cellular Putative RNA Helicase , 1999, Journal of Virology.

[39]  A. Gartel,et al.  Transcriptional regulation of the p21((WAF1/CIP1)) gene. , 1999, Experimental cell research.

[40]  D. Page,et al.  Functional coherence of the human Y chromosome. , 1997, Science.

[41]  R. Chuang,et al.  Requirement of the DEAD-Box Protein Ded1p for Messenger RNA Translation , 1997, Science.

[42]  Xiao-Fan Wang,et al.  Functional Analysis of the Transforming Growth Factor βResponsive Elements in the WAF1/Cip1/p21 Promoter (*) , 1995, The Journal of Biological Chemistry.

[43]  K. Kinzler,et al.  p21 is necessary for the p53-mediated G1 arrest in human cancer cells. , 1995, Cancer research.

[44]  B. Vogelstein,et al.  Absence of WAF1 mutations in a variety of human malignancies. , 1994, Blood.

[45]  J. Trent,et al.  WAF1, a potential mediator of p53 tumor suppression , 1993, Cell.

[46]  S. Chen,et al.  Suppression of hepatitis B virus expression and replication by hepatitis C virus core protein in HuH-7 cells , 1993, Journal of virology.

[47]  K. Arai,et al.  SR alpha promoter: an efficient and versatile mammalian cDNA expression system composed of the simian virus 40 early promoter and the R-U5 segment of human T-cell leukemia virus type 1 long terminal repeat , 1988, Molecular and cellular biology.

[48]  Y. Sadovsky,et al.  The DEAD box protein DP103 is a regulator of steroidogenic factor-1. , 2001, Molecular endocrinology.