TY - JOUR
T1 - Hedgehog
T2 - An attribute to tumor regrowth after chemoradiotherapy and a target to improve radiation response
AU - Sims-Mourtada, Jennifer
AU - Izzo, Julie G.
AU - Apisarnthanarax, Smith
AU - Wu, Tsung Teh
AU - Malhotra, Usha
AU - Luthra, Rajyalashmi
AU - Liao, Zhongxing
AU - Komaki, Ritsuko
AU - Van Der Kogel, Albert
AU - Ajani, Jaffer
AU - Chao, K. S.Clifford
PY - 2006/11/1
Y1 - 2006/11/1
N2 - Purpose: Despite aggressive chemotherapy, radiotherapy, surgery, or combination approaches, the survival rate of patients with esophageal cancer remains poor. Recent studies have suggested that constitutive activation of the Hedgehog (Hh) pathway in cancers of the digestive tract may contribute to the growth and maintenance of cancer. However, the relationship between Hh signaling and therapeutic response is unknown. Experimental Design: The expression and temporal kinetics of Hh signaling and proliferation biomarkers after chemoradiotherapy were examined in esophageal tumor xenografts. Additionally, immunohistochemical analysis of Sonic Hh (Shh) and Gli-1 expression were done on residual tumors from patients who received neoadjuvant chemoradiotherapy followed by surgery. The ability of Shh signaling to induce proliferation in esophageal cell lines was determined. Expression of cell cycle checkpoint proteins was analyzed in cells in which Hh signaling was activated or inhibited. We further determined the effect of inhibiting Hh signaling in sensitizing esophageal tumors to radiation. Results: We showed that the Shh signaling pathway was extensively activated in esophageal cancer xenografts and residual tumors after chemoradiotherapy and the temporal kinetics of Hh signaling preceded increases in proliferation biomarker expression and tumor size during tumor regrowth. We further showed that Hh pathway activity influences proliferation rates of esophageal cancer cell lines through up-regulation of the G1-cyclin-Rb axis. Additionally, we found that blocking Hh signaling enhanced radiation cytotoxicity of esophageal cancer cells. Conclusions: These results suggest that activation of the Hh pathway may promote tumor repopulation after chemoradiotherapy and contribute to chemoradiation resistance in esophageal cancers.
AB - Purpose: Despite aggressive chemotherapy, radiotherapy, surgery, or combination approaches, the survival rate of patients with esophageal cancer remains poor. Recent studies have suggested that constitutive activation of the Hedgehog (Hh) pathway in cancers of the digestive tract may contribute to the growth and maintenance of cancer. However, the relationship between Hh signaling and therapeutic response is unknown. Experimental Design: The expression and temporal kinetics of Hh signaling and proliferation biomarkers after chemoradiotherapy were examined in esophageal tumor xenografts. Additionally, immunohistochemical analysis of Sonic Hh (Shh) and Gli-1 expression were done on residual tumors from patients who received neoadjuvant chemoradiotherapy followed by surgery. The ability of Shh signaling to induce proliferation in esophageal cell lines was determined. Expression of cell cycle checkpoint proteins was analyzed in cells in which Hh signaling was activated or inhibited. We further determined the effect of inhibiting Hh signaling in sensitizing esophageal tumors to radiation. Results: We showed that the Shh signaling pathway was extensively activated in esophageal cancer xenografts and residual tumors after chemoradiotherapy and the temporal kinetics of Hh signaling preceded increases in proliferation biomarker expression and tumor size during tumor regrowth. We further showed that Hh pathway activity influences proliferation rates of esophageal cancer cell lines through up-regulation of the G1-cyclin-Rb axis. Additionally, we found that blocking Hh signaling enhanced radiation cytotoxicity of esophageal cancer cells. Conclusions: These results suggest that activation of the Hh pathway may promote tumor repopulation after chemoradiotherapy and contribute to chemoradiation resistance in esophageal cancers.
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U2 - 10.1158/1078-0432.CCR-06-0176
DO - 10.1158/1078-0432.CCR-06-0176
M3 - Article
C2 - 17085672
SN - 1078-0432
VL - 12
SP - 6565
EP - 6572
JO - Clinical Cancer Research
JF - Clinical Cancer Research
IS - 21
ER -