Deregulation of EGFR/VEGF/HIF-1a signaling pathway in colon adenocarcinoma based on tissue microarrays analysis.
OBJECTIVE
Overexpression of epidermal growth factor receptor (EGFR) and vascular endothelial growth factor (VEGF) in colon adenocarcinoma (CA) is a frequent event, whereas specific deregulation mechanisms in the corresponding signaling pathways remain under investigation. Our aim was to co-evaluate their expression correlated to the hypoxia inducible factor 1alpha (HIF-1a), which activates the transcription of VEGF gene.


METHODS
60 paraffin-embedded primary CAs were cored at 1.5 mm diameter and transferred to the microarray block. Immunohistochemistry (IHC) was performed using anti-EGFR, -VEGF, and -HIF 1a monoclonal antibodies. Concerning EGFR, quantitative evaluation was based on a semi-automated analysis system. Chromogenic in situ hybridization (CISH) was performed using EGFR gene and chromosome 7 centromeric probes.


RESULTS
Protein overexpression was observed in 13/60 (21.6%), 45/60 (75%) and 7/60 (11.6%) cases regarding EGFR, VEGF, and HIF 1a, respectively. CISH analysis detected 4/60 (6.6%) EGFR gene amplified cases, whereas chromosome 7 aneuploidy was identified in 11/60 (18.3%) cases. Significant associations raised correlating stage to chromosome 7 (p=0.024), HIF 1a expression to tumor anatomical location (p=0.019) and also VEGF to HIF 1a expression (p=0.001), whereas EGFR expression was not associated to EGFR gene copies.


CONCLUSIONS
According to our results, chromosome 7 instability is correlated to advanced disease, whereas a significant subset of CAs demonstrates an alternative, non- HIF 1a depended mechanism of VEGF overexpression. Furthermore, EGFR protein overexpression does not predict a specific gene deregulation mechanism.
Rigopoulos
D N
DN
Department of Internal Medicine, 401 General Army Hospital, Athens, Greece.
Tsiambas
E
E
Lazaris
A C
AC
Kavantzas
N
N
Papazachariou
I
I
Kravvaritis
C
C
Tsounis
D
D
Koliopoulou
A
A
Athanasiou
A E
AE
Karameris
A
A
Manaios
L
L
Sergentanis
T N
TN
Patsouris
E
E
D000230:Adenocarcinoma / Q000737:chemistry* / Q000235:genetics / Q000473:pathology; D000368:Aged; D000369:Aged, 80 and over; D000782:Aneuploidy; D043171:Chromosomal Instability; D002897:Chromosomes, Human, Pair 7; D003110:Colonic Neoplasms / Q000737:chemistry* / Q000235:genetics / Q000473:pathology; D066246:ErbB Receptors / Q000032:analysis* / Q000235:genetics; D005260:Female; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D051795:Hypoxia-Inducible Factor 1, alpha Subunit / Q000032:analysis*; D007150:Immunohistochemistry; D017403:In Situ Hybridization; D008297:Male; D008875:Middle Aged; D009367:Neoplasm Staging; D016612:Paraffin Embedding; D015398:Signal Transduction / Q000235:genetics; D046888:Tissue Array Analysis; D042461:Vascular Endothelial Growth Factor A / Q000032:analysis*
C497442:HIF1A protein, human; D051795:Hypoxia-Inducible Factor 1, alpha Subunit; C467484:VEGFA protein, human; D042461:Vascular Endothelial Growth Factor A; C512478:EGFR protein, human; D066246:ErbB Receptors