title: Role of PAX8 in the regulation of MET and RON receptor tyrosine kinases in non-small cell lung cancer.
abstract: BACKGROUND
  Non-small cell lung cancers (NSCLC) are highly heterogeneous at the molecular level and comprise 75% of all lung tumors. We have previously shown that the receptor tyrosine kinase (RTK) MET frequently suffers gain-of-function mutations that significantly promote lung tumorigenesis. Subsequent studies from our lab also revealed that PAX5 transcription factor is preferentially expressed in small cell lung cancer (SCLC) and promotes MET transcription. PAX8, however, is also expressed in NSCLC cell lines. We therefore investigated the role of PAX8 in NSCLC.
  
  
  METHODS
  Using IHC analysis, PAX8 protein expression was determined in archival NSCLC tumor tissues (n = 254). In order to study the effects of PAX8 knockdown on NSCLC cellular functions such as apoptosis and motility, siRNA against PAX8 was used. Confocal fluorescence microscopy was used to monitor the localization of MET, RON and PAX8. The combinatorial effect of PAX8 knockdown and MET inhibition using SU11274 was investigated in NSCLC cell viability assay.
  
  
  RESULTS
  Relative levels of PAX8 protein were elevated (≥ + 2 on a scale of 0-3) in adenocarcinoma (58/94), large cell carcinoma (50/85), squamous cell carcinoma (28/47), and metastatic NSCLC (17/28; lymph node). Utilizing early progenitors isolated from NSCLC cell lines and fresh tumor tissues, we observed robust overexpression of PAX8, MET, and RON. PAX8 knockdown A549 cells revealed abrogated PAX8 expression with a concomitant loss in MET and the related RON kinase expression. A dramatic colocalization between the active form of MET (also RON) and PAX8 upon challenging A549 cells with HGF was visualized. A similar colocalization of MET and EGL5 (PAX8 ortholog) proteins was found in embryos of C. elegans. Most importantly, knockdown of PAX8 in A549 cells resulted in enhanced apoptosis (~6 fold) and decreased cell motility (~45%), thereby making PAX8 a potential therapeutic target. However, the combinatorial approach of PAX8 knockdown and treatment with MET inhibitor, SU11274, had marginal additive effect on loss of NSCLC cell viability.
  
  
  CONCLUSIONS
  PAX8 provides signals for growth and motility of NSCLC cells and is necessary for MET and RON expression. Further investigations are necessary to investigate the therapeutic potential of PA8 in NSCLC.
authors.forename: Rajani
authors.initials: R
authors.lastname: Kanteti
authors.forename: Essam
authors.initials: E
authors.lastname: El-Hashani
authors.forename: Immanuel
authors.initials: I
authors.lastname: Dhanasingh
authors.forename: Maria
authors.initials: M
authors.lastname: Tretiakova
authors.forename: Aliya N
authors.initials: AN
authors.lastname: Husain
authors.forename: Sherven
authors.initials: S
authors.lastname: Sharma
authors.forename: Jay
authors.initials: J
authors.lastname: Sharma
authors.forename: Everett E
authors.initials: EE
authors.lastname: Vokes
authors.affiliation: Department of Hematology/Oncology, University of Chicago Medical Center, Chicago, IL, USA. rsalgia@medicine.bsd.uchicago.edu.
authors.forename: Ravi
authors.initials: R
authors.lastname: Salgia
mesh_terms: D000230:Adenocarcinoma / Q000378:metabolism / Q000473:pathology; D000818:Animals; D017209:Apoptosis; D017173:Caenorhabditis elegans / Q000196:embryology / Q000378:metabolism; D018287:Carcinoma, Large Cell / Q000378:metabolism / Q000473:pathology; D002289:Carcinoma, Non-Small-Cell Lung / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D002294:Carcinoma, Squamous Cell / Q000378:metabolism / Q000473:pathology; D045744:Cell Line, Tumor; D002465:Cell Movement; D015972:Gene Expression Regulation, Neoplastic; D055785:Gene Knockdown Techniques; D017228:Hepatocyte Growth Factor / Q000378:metabolism*; D006801:Humans; D007211:Indoles / Q000494:pharmacology; D008207:Lymphatic Metastasis; D000072636:PAX8 Transcription Factor; D051761:Paired Box Transcription Factors / Q000235:genetics / Q000378:metabolism*; D010879:Piperazines / Q000494:pharmacology; D019859:Proto-Oncogene Proteins c-met / Q000378:metabolism*; D020794:Receptor Protein-Tyrosine Kinases / Q000378:metabolism*; D013449:Sulfonamides / Q000494:pharmacology
chemical_list: C478479:((3Z)-N-(3-chlorophenyl)-3-((3,5-dimethyl-4-((4-methylpiperazin-1-yl)carbonyl)-1H-pyrrol-2-yl)methylene)-N-methyl-2-oxo-2,3-dihydro-1H-indole-5-sulfonamide); D007211:Indoles; D000072636:PAX8 Transcription Factor; C083325:PAX8 protein, human; D051761:Paired Box Transcription Factors; D010879:Piperazines; D013449:Sulfonamides; D017228:Hepatocyte Growth Factor; C491743:MET protein, human; D019859:Proto-Oncogene Proteins c-met; C080835:RON protein; D020794:Receptor Protein-Tyrosine Kinases