Simultaneous EGFR and VEGF alterations in non-small cell lung carcinoma based on tissue microarrays

Abstract

Background: Epidermal growth factor receptor (EGFR) overexpression is observed in significant proportions of non-small cell lung carcinomas (NSCLC). Furthermore, overactivation of vascular endothelial growth factor (VEGF) leads to increased angiogenesis implicated as an important factor in vascularization of those tumors.

Patients and methods: Using tissue microarray technology, forty-paraffin (n = 40) embedded, histologically confirmed primary NSCLCs were cored and re-embedded into a recipient block. Immunohistochemistry was performed for the determination of EGFR and VEGF protein levels which were evaluated by the performance of computerized image analysis. EGFR gene amplification was studied by chromogenic in situ hybridization based on the use of EGFR gene and chromosome 7 centromeric probes.

Results: EGFR overexpression was observed in 23/40 (57.5%) cases and was correlated to the stage of the tumors (p = 0.001), whereas VEGF was overexpressed in 35/40 (87.5%) cases and was correlated to the stage of the tumors (p = 0.005) and to the smoking history of the patients (p = 0.016). Statistical significance was assessed comparing the protein levels of EGFR and VEGF (p = 0.043, k = 0.846). EGFR gene amplification was identified in 2/40 (5%) cases demonstrating no association to its overall protein levels (p = 0.241), whereas chromosome 7 aneuploidy was detected in 7/40 (17.5%) cases correlating to smoking history of the patients (p = 0.013).

Conclusions: A significant subset of NSCLC is characterized by EGFR and VEGF simultaneous overexpression and maybe this is the eligible target group for the application of combined anti-EGFR/VEGF targeted therapies at the basis of genetic deregulation (especially gene amplification for EGFR).

Keywords: Non-small cell lung carcinoma; epidermal growth factor receptor; genes; tissue microarrays; vascular endothelial growth factor.

Figure 1.

EGFR overexpression was found in a case of NSCLC. (A) A tissue microarray core (diameter 1 mm) demonstrating EGFR high value of protein expression (conventional score 3+). Original magnification: 10× (B). Note in the same case the specific—for protein overexpression-complete, “ring like”, dense membranous predominantly immunostaining pattern (clone 31G7). Original magnification: 40× upper inside. Chromosome 7 aneuploidy by CISH analysis. Note 3 and 4 centromeric signals per nucleus (black arrows) down inside. EGFR gene amplification by CISH analysis. Note 6–10 gene copies as dark blue scattered signals or small clusters of them (red arrows) per nucleus. Original magnification for CISH: 40×.

Figure 2.

VEGF protein expression evaluated by Computerized Image analysis shows Reddish areas that represent cytoplasmic and membranous immunostaining.