Hedgehog Pathway as a Potential Intervention Target in Esophageal Cancer

Esophageal cancer (EC) is an aggressive disease with a poor prognosis. Treatment resistance is a major challenge in successful anti-cancer therapy. Pathological complete response after neoadjuvant chemoradiation (nCRT) is low, thus requiring therapy optimization. The Hedgehog (HH) pathway has been implicated in therapy resistance, as well as in cancer stemness. This article focusses on the HH pathway as a putative target in the treatment of EC. Immunohistochemistry on HH members was applied to EC patient material followed by modulation of 3D-EC cell cultures, fluorescence-activated cell sorting (FACS), and gene expression analysis after HH pathway modulation. Sonic Hedgehog (SHH) and its receptor Patched1 (PTCH1) were significantly enriched in EC resection material of patients with microresidual disease (mRD) after receiving nCRT, compared to the control group. Stimulation with SHH resulted in an up-regulation of cancer stemness in EC sphere cultures, as indicated by increased sphere formation after sorting for CD44+/CD24- EC cancer stem-like cell (CSC) population. On the contrary, inhibiting this pathway with vismodegib led to a decrease in cancer stemness and both radiation and carboplatin resistance. Our results strengthen the role of the HH pathway in chemoradiotherapy resistance. These findings suggest that targeting the HH pathway could be an attractive approach to control CSCs.