Maternal embryonic leucine zipper kinase/murine protein serine-threonine kinase 38 is a promising therapeutic target for multiple cancers.

To identify genes that could serve as targets for novel cancer therapeutics, we used a bioinformatic analysis of microarray data comparing gene expression between normal and tumor-derived primary human tissues. From this approach, we have found that maternal embryonic leucine zipper kinase (Melk), a member of the AMP serine/threonine kinase family, exhibits multiple features consistent with the potential utility of this gene as an anticancer target. An oligonucleotide microarray analysis of multiple human tumor samples and cell lines suggests that Melk expression is frequently elevated in cancer relative to normal tissues, a pattern confirmed by quantitative reverse transcription-PCR and Western blotting of selected primary tumor samples. In situ hybridization localized Melk expression to malignant epithelial cells in 96%, 23%, and 13% of colorectal, lung, and ovarian tissue tumor samples, respectively. Expression of this gene is also elevated in spontaneous tumors derived from the ApcMin and Apc1638N murine models of intestinal tumorigenesis. To begin addressing whether Melk is relevant for tumorigenesis, RNA interference-mediated silencing within human and murine tumor cell lines was done. We show that Melk knockdown decreases proliferation and anchorage-independent growth in vitro as well as tumor growth in a xenograft model. Together, these results suggest that Melk may provide a growth advantage for neoplastic cells and, therefore, inactivation may be therapeutically beneficial.

[1]  Y. Mishina,et al.  Conditional Transgenic System for Mouse Aurora A Kinase: Degradation by the Ubiquitin Proteasome Pathway Controls the Level of the Transgenic Protein , 2005, Molecular and Cellular Biology.

[2]  Yan Zhang,et al.  GEPIS - quantitative gene expression profiling in normal and cancer tissues , 2004, Bioinform..

[3]  R. Wilson,et al.  EGF receptor gene mutations are common in lung cancers from "never smokers" and are associated with sensitivity of tumors to gefitinib and erlotinib. , 2004, Proceedings of the National Academy of Sciences of the United States of America.

[4]  Prakash Chinnaiyan,et al.  Dual-Agent Molecular Targeting of the Epidermal Growth Factor Receptor (EGFR) , 2004, Cancer Research.

[5]  Armando Santoro,et al.  Cetuximab monotherapy and cetuximab plus irinotecan in irinotecan-refractory metastatic colorectal cancer. , 2004, The New England journal of medicine.

[6]  S. Gabriel,et al.  EGFR Mutations in Lung Cancer: Correlation with Clinical Response to Gefitinib Therapy , 2004, Science.

[7]  Patricia L. Harris,et al.  Activating mutations in the epidermal growth factor receptor underlying responsiveness of non-small-cell lung cancer to gefitinib. , 2004, The New England journal of medicine.

[8]  F. Peale,et al.  Expression of vascular endothelial growth factor, hypoxia inducible factor 1α, and carbonic anhydrase IX in human tumours , 2004, Journal of Clinical Pathology.

[9]  H. Esumi,et al.  ARK5 Is a Tumor Invasion-Associated Factor Downstream of Akt Signaling , 2004, Molecular and Cellular Biology.

[10]  M. Bollen,et al.  Inhibition of Spliceosome Assembly by the Cell Cycle-regulated Protein Kinase MELK and Involvement of Splicing Factor NIPP1* , 2004, Journal of Biological Chemistry.

[11]  M. Kaminishi,et al.  ARK5 expression in colorectal cancer and its implications for tumor progression. , 2004, The American journal of pathology.

[12]  Jérôme Boudeau,et al.  LKB1 is a master kinase that activates 13 kinases of the AMPK subfamily, including MARK/PAR‐1 , 2004, The EMBO journal.

[13]  D. Geschwind,et al.  Neural progenitor genes. Germinal zone expression and analysis of genetic overlap in stem cell populations. , 2003, Developmental biology.

[14]  Daniel H. Geschwind,et al.  Cancerous stem cells can arise from pediatric brain tumors , 2003, Proceedings of the National Academy of Sciences of the United States of America.

[15]  Minyoung Lee,et al.  AMP-activated Protein Kinase Activity Is Critical for Hypoxia-inducible Factor-1 Transcriptional Activity and Its Target Gene Expression under Hypoxic Conditions in DU145 Cells* , 2003, Journal of Biological Chemistry.

[16]  N. Socci,et al.  Oncogenic Ras and Akt signaling contribute to glioblastoma formation by differential recruitment of existing mRNAs to polysomes. , 2003, Molecular cell.

[17]  H. Saya,et al.  Aurora-A and an Interacting Activator, the LIM Protein Ajuba, Are Required for Mitotic Commitment in Human Cells , 2003, Cell.

[18]  J. Connell,et al.  Direct Activation of AMP-activated Protein Kinase Stimulates Nitric-oxide Synthesis in Human Aortic Endothelial Cells* , 2003, Journal of Biological Chemistry.

[19]  K. Walsh,et al.  AMP-activated Protein Kinase (AMPK) Signaling in Endothelial Cells Is Essential for Angiogenesis in Response to Hypoxic Stress* , 2003, Journal of Biological Chemistry.

[20]  F. Peale,et al.  Quantitative analysis of colorectal tissue microarrays by immunofluorescence and in situ hybridization , 2003, The Journal of pathology.

[21]  M. West,et al.  Distinct gene expression phenotypes of cells lacking Rb and Rb family members. , 2003, Cancer research.

[22]  Hui Zhao,et al.  Dual phosphorylation controls Cdc25 phosphatases and mitotic entry , 2003, Nature Cell Biology.

[23]  Kyong-Tai Kim,et al.  Enhancement of B-MYB Transcriptional Activity by ZPR9, a Novel Zinc Finger Protein* , 2003, The Journal of Biological Chemistry.

[24]  H. Esumi,et al.  Identification of a Novel Protein Kinase Mediating Akt Survival Signaling to the ATM Protein* , 2003, The Journal of Biological Chemistry.

[25]  T. Hunter,et al.  The Protein Kinase Complement of the Human Genome , 2002, Science.

[26]  A. D. de Vos,et al.  Vascular Endothelial Growth Factor–Induced Genes in Human Umbilical Vein Endothelial Cells: Relative Roles of KDR and Flt-1 Receptors , 2002, Arteriosclerosis, thrombosis, and vascular biology.

[27]  V. Baldin,et al.  Human pEg3 kinase associates with and phosphorylates CDC25B phosphatase: a potential role for pEg3 in cell cycle regulation , 2002, Oncogene.

[28]  M. Miyazaki,et al.  Critical roles of AMP-activated protein kinase in constitutive tolerance of cancer cells to nutrient deprivation and tumor formation , 2002, Oncogene.

[29]  R. Bernards,et al.  A System for Stable Expression of Short Interfering RNAs in Mammalian Cells , 2002, Science.

[30]  Kyong-Tai Kim,et al.  Phosphorylation of a novel zinc-finger-like protein, ZPR9, by murine protein serine/threonine kinase 38 (MPK38). , 2002, The Biochemical journal.

[31]  Lyndsay N Harris,et al.  Efficacy and safety of trastuzumab as a single agent in first-line treatment of HER2-overexpressing metastatic breast cancer. , 2002, Journal of clinical oncology : official journal of the American Society of Clinical Oncology.

[32]  B. Druker,et al.  Perspectives on the development of a molecularly targeted agent. , 2002, Cancer cell.

[33]  M. Philippe,et al.  Cell cycle regulation of pEg3, a new Xenopus protein kinase of the KIN1/PAR-1/MARK family. , 2002, Developmental biology.

[34]  T. Tuschl,et al.  Functional anatomy of siRNAs for mediating efficient RNAi in Drosophila melanogaster embryo lysate , 2001, The EMBO journal.

[35]  Thomas D. Schmittgen,et al.  Analysis of relative gene expression data using real-time quantitative PCR and the 2(-Delta Delta C(T)) Method. , 2001, Methods.

[36]  H. Clevers,et al.  APC, Signal transduction and genetic instability in colorectal cancer , 2001, Nature Reviews Cancer.

[37]  A. Fire,et al.  Specific inhibition of gene expression by small double-stranded RNAs in invertebrate and vertebrate systems , 2001, Proceedings of the National Academy of Sciences of the United States of America.

[38]  A. Forrest,et al.  Cdc25B activity is regulated by 14-3-3 , 2001, Oncogene.

[39]  P. Carbon,et al.  An unusually compact external promoter for RNA polymerase III transcription of the human H1RNA gene. , 2001, Nucleic acids research.

[40]  T. Fleming,et al.  Use of chemotherapy plus a monoclonal antibody against HER2 for metastatic breast cancer that overexpresses HER2. , 2001, The New England journal of medicine.

[41]  Irving L. Weissman,et al.  A Genetic Analysis of Neural Progenitor Differentiation , 2001, Neuron.

[42]  M. Waye,et al.  Specific interaction between 14-3-3 isoforms and the human CDC25B phosphatase , 2000, Oncogene.

[43]  D. Solter,et al.  Expression of Melk, a new protein kinase, during early mouse development , 1999, Developmental dynamics : an official publication of the American Association of Anatomists.

[44]  R. Watson,et al.  B‐Myb protein in cellular proliferation, transcription control, and cancer: Latest developments , 1999, Journal of cellular physiology.

[45]  A E Willis,et al.  Translational control of growth factor and proto-oncogene expression. , 1999, The international journal of biochemistry & cell biology.

[46]  F. Yao,et al.  Tetracycline repressor, tetR, rather than the tetR-mammalian cell transcription factor fusion derivatives, regulates inducible gene expression in mammalian cells. , 1998, Human gene therapy.

[47]  H. Ha,et al.  Cloning and expression of a cDNA encoding a novel protein serine/threonine kinase predominantly expressed in hematopoietic cells. , 1997, Gene.

[48]  D. Solter,et al.  New member of the Snf1/AMPK kinase family, Melk, is expressed in the mouse egg and preimplantation embryo , 1997, Molecular reproduction and development.

[49]  W. J. Pledger,et al.  Repression of p27kip1 synthesis by platelet-derived growth factor in BALB/c 3T3 cells , 1996, Molecular and cellular biology.

[50]  L. Hengst,et al.  Translational Control of p27Kip1 Accumulation During the Cell Cycle , 1996, Science.

[51]  N. Nomura,et al.  Prediction of the coding sequences of unidentified human genes. IV. The coding sequences of 40 new genes (KIAA0121-KIAA0160) deduced by analysis of cDNA clones from human cell line KG-1. , 1995, DNA research : an international journal for rapid publication of reports on genes and genomes.

[52]  J. Paris,et al.  Changes in the polyadenylation of specific stable RNA during the early development of Xenopus laevis. , 1988, Gene.

[53]  J. Walker,et al.  Rhodopseudomonas blastica atp operon. Nucleotide sequence and transcription. , 1984, Journal of molecular biology.

[54]  C. Gatz,et al.  Control of expression of the Tn10-encoded tetracycline resistance operon. II. Interaction of RNA polymerase and TET repressor with the tet operon regulatory region. , 1984, Journal of molecular biology.

[55]  V. Freedman,et al.  Tumorigenicity of virus-transformed cells in nude mice is correlated specifically with anchorage independent growth in vitro. , 1975, Proceedings of the National Academy of Sciences of the United States of America.

[56]  L. Montagnier,et al.  AGAR SUSPENSION CULTURE FOR THE SELECTIVE ASSAY OF CELLS TRANSFORMED BY POLYOMA VIRUS. , 1964, Virology.