The expression of epidermal growth factor receptor and its downstream signaling molecules in osteosarcoma

The value of epidermal growth factor receptor (EGFR) and its downstream signaling molecules as prognostic factors have been studied in many tumor types. The aim of this study was to investigate whether these molecules have prognostic value in osteosarcoma. We evaluated the immunostaining of EGFR and its downstream signaling molecules, p-EGFR, Akt, Stat-3, survivin and Erk in 47 osteosarcomas. In addition, three osteosarcoma cell lines were used to evaluate EGFR expression levels and mutation status by real-time PCR and nucleotide sequence analysis. Using tissue microarray of samples from 47 paraffin-embedded osteosarcoma cases, 26, 17, 20 and 12 cases showed positive immunostaining of EGFR, Stat-3, survivin and Erk, respectively. Survivin and Erk were statistically correlated with survival (p=0.005 and p=0.002, respectively, log-rank test). Furthermore, we found that EGFR expression was correlated with Erk expression. In addition, we also observed a significant association of survivin expression with Stat-3 and Erk activation (p=0.006 and p=0.000, Fisher's exact test). p-EGFR and Akt immunostaining were not detected in any of the cases. Two out of three osteosarcoma cell lines showed increased EGFR levels as detected by real-time PCR. One of these cell lines had a CAA to CAG mutation at exon 20 of the amplified EGFR gene, but this did not change the amino acid sequence. These results support the idea that Erk is a downstream signaling molecule of EGFR. Moreover, our data indicate that survivin and Erk could be used as prognostic factors in patients with osteosarcoma.