Potential Contribution of Epithelial Growth Factor Receptor to PI3K/AKT Pathway Dysregulation in Canine Soft Tissue Sarcoma.

BACKGROUND/AIM: Soft tissue sarcoma (STS) is a mesenchymal tumor affecting multiple organs in dogs. Previous studies identified activation of the phosphatidylinositol-3 kinase (PI3K)/protein kinase B (PKB, AKT) pathway in canine STS cell lines and clinical samples, but the underlying mechanism remains unclear. This study investigated PTEN loss, PIK3CA mutation, and EGFR over-expression as potential drivers of PI3K/AKT pathway activation in STS.

MATERIALS AND METHODS

We analyzed 36 canine STS samples. PTEN and EGFR expression were evaluated using immunohistochemistry, while PIK3CA and EGFR mutations were assessed through DNA sequencing.

RESULTS

PTEN was expressed in all analyzed samples, with no evidence of loss. Weak PTEN expression was observed in 12 (33.3%) samples, while 24 (66.7%) showed normal expression. DNA sequencing of PIK3CA revealed a single point mutation (c.554 A>C, H554P) in one case, but no hotspot mutations were identified. High EGFR expression was significantly correlated with elevated phospho-AKT levels (p<0.0001). Immunolabelling indicated that 30 samples (83.3%) were EGFR-positive, and 27 of these also showed positive phospho-AKT labeling. Accordingly, one missense point mutation in exon 21 of EGFR (E868K) was identified in one of 12 samples.

CONCLUSION

EGFR over-expression, rather than PTEN loss or PIK3CA mutations, may contribute to PI3K/AKT pathway dysregulation in canine STS. Further studies with larger sample sizes and additional validation techniques are necessary to confirm these findings.