Left ventricular unloading alters receptor tyrosine kinase expression in the failing human heart.
BACKGROUND
Experimental and clinical data suggest that the loss of membrane receptor tyrosine kinase (RTK) activity in cardiac myocytes results in increased frequency of apoptotic cell death and progression of heart failure. The goal of our study was to examine the expression characteristics of RTKs in ventricular myocardium obtained from patients before and after mechanical unloading.


METHODS
We extracted RNA from paired formalin-fixed, paraffin-embedded left ventricular tissue blocks obtained at the time of left ventricular assist device (LVAD) implantation and explantation from a cohort of 36 patients (median age 51 years). The duration of LVAD support ranged from 1 to 314 days (median 95 days), 17 patients had ischemic and 19 non-ischemic cardiomyopathy at the time of LVAD implantation. Using real-time reverse transcription-polymerase chain reaction (RT-PCR) we quantitated transcripts for atrial natriuretic factor (ANF) and tumor necrosis factor-alpha (TNF-alpha), markers of heart failure, and the RTKs Her2/neu, Her4 and gp130, regulators of cardiac cell survival.


RESULTS
In patients undergoing mechanical unloading, ANF and TNF-alpha mRNA levels were independently suppressed. Her2/neu, along with Her4 was upregulated, mostly in cases of ischemic cardiomyopathy, whereas gp130 levels decreased. Post-LVAD transcript levels of Her2 correlated tightly with gp130 in patients with non-pathologic entry values of gp130. Duration of treatment and age were also determining factors in the change of expression of these genes.


CONCLUSIONS
Real-time quantitative (Q)-RT-PCR can be used to quantitate gene expression in archival myocardial tissue blocks. Mechanical unloading leads to a re-adjustment of RTK transcript levels, but not their reverting to control values in heart failure patients.
Uray
Iván P
IP
Department of Integrative Biology and Pharmacology, University of Texas at Houston Medical School, Houston, Texas 77225, USA.
Connelly
John H
JH
Thomázy
Vilmos
V
Shipley
Gregory L
GL
Vaughn
William K
WK
Frazier
O Howard
OH
Taegtmeyer
Heinrich
H
Davies
Peter J A
PJ
D000293:Adolescent; D000328:Adult; D000368:Aged; D015703:Antigens, CD / Q000235:genetics*; D050822:Cytokine Receptor gp130; D066246:ErbB Receptors / Q000235:genetics*; D005260:Female; D015870:Gene Expression; D018734:Genes, erbB-2 / Q000235:genetics*; D006333:Heart Failure / Q000235:genetics* / Q000503:physiopathology; D006352:Heart Ventricles / Q000503:physiopathology; D006353:Heart-Assist Devices; D006801:Humans; D008297:Male; D008562:Membrane Glycoproteins / Q000235:genetics*; D008875:Middle Aged; D066247:Receptor, ErbB-4; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014158:Transcription, Genetic; D015854:Up-Regulation
D015703:Antigens, CD; C494199:IL6ST protein, human; D008562:Membrane Glycoproteins; D050822:Cytokine Receptor gp130; C587689:ERBB4 protein, human; D066246:ErbB Receptors; D066247:Receptor, ErbB-4