title: RhoA: a therapeutic target for chronic myeloid leukemia.
abstract: BACKGROUND
  Chronic Myeloid Leukemia (CML) is a malignant pluripotent stem cells disorder of myeloid cells. In CML patients, polymorphonuclear leukocytes (PMNL) the terminally differentiated cells of myeloid series exhibit defects in several actin dependent functions such as adhesion, motility, chemotaxis, agglutination, phagocytosis and microbicidal activities. A definite and global abnormality was observed in stimulation of actin polymerization in CML PMNL. Signalling molecules ras and rhoGTPases regulate spatial and temporal polymerization of actin and thus, a broad range of physiological processes. Therefore, status of these GTPases as well as actin was studied in resting and fMLP stimulated normal and CML PMNL.
  
  
  METHODS
  To study expression of GTPases and actin, Western blotting and flow cytometry analysis were done, while spatial expression and colocalization of these proteins were studied by using laser confocal microscopy. To study effect of inhibitors on cell proliferation CCK-8 assay was done. Significance of differences in expression of proteins within the samples and between normal and CML was tested by using Wilcoxon signed rank test and Mann-Whitney test, respectively. Bivariate and partial correlation analyses were done to study relationship between all the parameters.
  
  
  RESULTS
  In CML PMNL, actin expression and its architecture were altered and stimulation of actin polymerization was absent. Differences were also observed in expression, organization or stimulation of all the three GTPases in normal and CML PMNL. In normal PMNL, ras was the critical GTPase regulating expression of rhoGTPases and actin and actin polymerization. But in CML PMNL, rhoA took a central place. In accordance with these, treatment with rho/ROCK pathway inhibitors resulted in specific growth inhibition of CML cell lines.
  
  
  CONCLUSIONS
  RhoA has emerged as the key molecule responsible for functional defects in CML PMNL and therefore can be used as a therapeutic target in CML.
authors.affiliation: Cancer Research Institute, ACTREC, Tata Memorial Centre, Kharghar, Navi Mumbai 410210, India.
authors.forename: Poonam R
authors.initials: PR
authors.lastname: Molli
authors.forename: Madhura B
authors.initials: MB
authors.lastname: Pradhan
authors.forename: Suresh H
authors.initials: SH
authors.lastname: Advani
authors.forename: Nishigandha R
authors.initials: NR
authors.lastname: Naik
mesh_terms: D036002:ADP Ribose Transferases / Q000494:pharmacology; D000199:Actins / Q000378:metabolism; D000577:Amides / Q000494:pharmacology; D015153:Blotting, Western; D001905:Botulinum Toxins / Q000494:pharmacology; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects; D002478:Cells, Cultured; D005455:Fluorescent Antibody Technique; D020558:GTP Phosphohydrolases / Q000037:antagonists & inhibitors / Q000378:metabolism; D018922:HL-60 Cells; D006801:Humans; D007951:Leukemia, Myeloid / Q000378:metabolism*; D009504:Neutrophils / Q000187:drug effects / Q000378:metabolism; D011725:Pyridines / Q000494:pharmacology; D020742:rhoA GTP-Binding Protein / Q000037:antagonists & inhibitors / Q000378:metabolism*
chemical_list: D000199:Actins; D000577:Amides; D011725:Pyridines; C108830:Y 27632; D036002:ADP Ribose Transferases; C063007:exoenzyme C3, Clostridium botulinum; D001905:Botulinum Toxins; D020558:GTP Phosphohydrolases; D020742:rhoA GTP-Binding Protein