title: RASSF1C modulates the expression of a stem cell renewal gene, PIWIL1.
abstract: BACKGROUND
  RASSF1A and RASSF1C are two major isoforms encoded by the Ras association domain family 1 (RASSF1) gene through alternative promoter selection and mRNA splicing. RASSF1A is a well established tumor suppressor gene. Unlike RASSF1A, RASSF1C appears to have growth promoting actions in lung cancer. In this article, we report on the identification of novel RASSF1C target genes in non small cell lung cancer (NSCLC).
  
  
  METHODS
  Over-expression and siRNA techniques were used to alter RASSF1C expression in human lung cancer cells, and Affymetrix-microarray study was conducted using NCI-H1299 cells over-expressing RASSF1C to identify RASSF1C target genes.
  
  
  RESULTS
  The microarray study intriguingly shows that RASSF1C modulates the expression of a number of genes that are involved in cancer development, cell growth and proliferation, cell death, and cell cycle. We have validated the expression of some target genes using qRT-PCR. We demonstrate that RASSF1C over-expression increases, and silencing of RASSF1C decreases, the expression of PIWIL1 gene in NSCLC cells using qRT-PCR, immunostaining, and Western blot analysis. We also show that RASSF1C over-expression induces phosphorylation of ERK1/2 in lung cancer cells, and inhibition of the MEK-ERK1/2 pathway suppresses the expression of PIWIL1 gene expression, suggesting that RASSF1C may exert its activities on some target genes such as PIWIL1 through the activation of the MEK-ERK1/2 pathway. Also, PIWIL1 expression is elevated in lung cancer cell lines compared to normal lung epithelial cells.
  
  
  CONCLUSIONS
  Taken together, our findings provide significant data to propose a model for investigating the role of RASSF1C/PIWIL1 proteins in initiation and progression of lung cancer.
authors.affiliation: Surgical Oncology Laboratory, Loma Linda VA Medical Center, CA 92357, USA.
authors.forename: Mark E
authors.initials: ME
authors.lastname: Reeves
authors.forename: Melissa L
authors.initials: ML
authors.lastname: Baldwin
authors.forename: Robert
authors.initials: R
authors.lastname: Aragon
authors.forename: Scott
authors.initials: S
authors.lastname: Baldwin
authors.forename: Shin-Tai
authors.initials: ST
authors.lastname: Chen
authors.forename: Xinmin
authors.initials: X
authors.lastname: Li
authors.forename: Subburaman
authors.initials: S
authors.lastname: Mohan
authors.forename: Yousef G
authors.initials: YG
authors.lastname: Amaar
mesh_terms: D017209:Apoptosis / Q000235:genetics; D060565:Argonaute Proteins / Q000235:genetics* / Q000378:metabolism; D001549:Benzamides / Q000494:pharmacology; D015153:Blotting, Western; D002289:Carcinoma, Non-Small-Cell Lung / Q000235:genetics / Q000378:metabolism / Q000473:pathology; D002453:Cell Cycle / Q000235:genetics; D002460:Cell Line; D045744:Cell Line, Tumor; D049109:Cell Proliferation; D048049:Extracellular Signal-Regulated MAP Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism; D020869:Gene Expression Profiling; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects / Q000235:genetics*; D006801:Humans; D007150:Immunohistochemistry; D008175:Lung Neoplasms / Q000235:genetics / Q000378:metabolism / Q000473:pathology; D020935:MAP Kinase Signaling System / Q000187:drug effects; D014411:Neoplastic Stem Cells / Q000378:metabolism*; D020411:Oligonucleotide Array Sequence Analysis; D010766:Phosphorylation / Q000187:drug effects; D034622:RNA Interference; D020133:Reverse Transcriptase Polymerase Chain Reaction; D025521:Tumor Suppressor Proteins / Q000235:genetics* / Q000378:metabolism
chemical_list: C120227:2-(2-chloro-4-iodophenylamino)-N-cyclopropylmethoxy-3,4-difluorobenzamide; D060565:Argonaute Proteins; D001549:Benzamides; C421088:PIWIL1 protein, human; C411762:RASSF1 protein, human; D025521:Tumor Suppressor Proteins; D048049:Extracellular Signal-Regulated MAP Kinases