Q6, a novel hypoxia-targeted drug, regulates hypoxia-inducible factor signaling via an autophagy-dependent mechanism in hepatocellular carcinoma.
Tumor hypoxia underlies treatment failure and yields more aggressive and metastatic cancer phenotypes. Although therapeutically targeting these hypoxic environments has been proposed for many years, to date no approaches have shown the therapeutic value to gain regulatory approval. Here, we demonstrated that a novel hypoxia-activated prodrug, Q6, exhibits potent antiproliferative efficacy under hypoxic conditions and induces caspase-dependent apoptosis in 2 hepatocellular carcinoma (HCC) cell lines, with no obvious toxicity being detected in 2 normal liver cell lines. Treatment with Q6 markedly downregulated HIF1A [hypoxia inducible factor 1, α subunit (basic helix-loop-helix transcription factor)] expression and transcription of the downstream target gene, VEGFA (vascular endothelial growth factor A). This dual hypoxia-targeted modulation mechanism leads to high potency in suppressing tumor growth and vascularization in 2 in vivo models. Intriguingly, it is the autophagy-dependent degradation pathway that plays a crucial role in Q6-induced attenuation of HIF1A expression, rather than the proteasome-dependent pathway, which is normally regarded as the predominant mechanism underlying posttranslational regulation of HIF1A. Inhibition of autophagy, either by short interfering RNA (siRNA) or by chemical inhibitors, blocked Q6-induced HIF1A degradation. Autophagic degradation of HIF1A was further confirmed by the observation that HIF1A coimmunoprecipitated with the ubiquitin-binding adaptor protein, SQSTM1, which is degraded through autophagy. Additionally, silencing of SQSTM1 inhibited Q6-induced HIF1A degradation. These findings suggest that the novel hypoxia-targeted agent, Q6, has potential clinical value in the therapy of HCC. Furthermore, the identification of autophagy as a crucial regulator of HIF1A provides new insights into hypoxia-related treatments.
Zhejiang Province Key Laboratory of Anti-Cancer Drug Research; Institute of Pharmacology and Toxicology; College of Pharmaceutical Sciences; Zhejiang University; Hangzhou, China.
Xiao-Wen
XW
Liu
Zhejiang Province Key Laboratory of Anti-Cancer Drug Research; Institute of Pharmacology and Toxicology; College of Pharmaceutical Sciences; Zhejiang University; Hangzhou, China.
Tian-Yu
TY
Cai
Zhejiang Province Key Laboratory of Anti-Cancer Drug Research; Institute of Pharmacology and Toxicology; College of Pharmaceutical Sciences; Zhejiang University; Hangzhou, China.
Hong
H
Zhu
Zhejiang Province Key Laboratory of Anti-Cancer Drug Research; Institute of Pharmacology and Toxicology; College of Pharmaceutical Sciences; Zhejiang University; Hangzhou, China.
Ji
J
Cao
Zhejiang Province Key Laboratory of Anti-Cancer Drug Research; Institute of Pharmacology and Toxicology; College of Pharmaceutical Sciences; Zhejiang University; Hangzhou, China.
Yi
Y
Su
ZJU-ENS Joint laboratory of Medicinal Chemistry; College of Pharmaceutical Sciences; Zhejiang University; Hangzhou, China.
Yong-Zhou
YZ
Hu
Zhejiang Province Key Laboratory of Anti-Cancer Drug Research; Institute of Pharmacology and Toxicology; College of Pharmaceutical Sciences; Zhejiang University; Hangzhou, China.
Qiao-Jun
QJ
He
Zhejiang Province Key Laboratory of Anti-Cancer Drug Research; Institute of Pharmacology and Toxicology; College of Pharmaceutical Sciences; Zhejiang University; Hangzhou, China.
Bo
B
Yang
D048868:Adaptor Proteins, Signal Transducing / Q000378:metabolism; D000818:Animals; D000970:Antineoplastic Agents / Q000494:pharmacology; D017209:Apoptosis / Q000187:drug effects; D001343:Autophagy / Q000187:drug effects*; D000071187:Autophagy-Related Protein 5; D006528:Carcinoma, Hepatocellular / Q000378:metabolism / Q000473:pathology / Q000648:ultrastructure; D020169:Caspases / Q000378:metabolism; D015687:Cell Hypoxia / Q000187:drug effects; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects; D015536:Down-Regulation / Q000187:drug effects; D051795:Hypoxia-Inducible Factor 1, alpha Subunit / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D008113:Liver Neoplasms / Q000378:metabolism / Q000473:pathology* / Q000648:ultrastructure; D008247:Lysosomes / Q000187:drug effects / Q000378:metabolism / Q000648:ultrastructure; D051379:Mice; D008819:Mice, Nude; D008869:Microtubule-Associated Proteins / Q000378:metabolism; D059748:Proteolysis / Q000187:drug effects; D011810:Quinoxalines / Q000494:pharmacology*; D000071456:Sequestosome-1 Protein; D015398:Signal Transduction / Q000187:drug effects / Q000235:genetics; D014158:Transcription, Genetic / Q000187:drug effects
C502778:ATG5 protein, human; D048868:Adaptor Proteins, Signal Transducing; D000970:Antineoplastic Agents; D000071187:Autophagy-Related Protein 5; D051795:Hypoxia-Inducible Factor 1, alpha Subunit; C502070:MAP1LC3B protein, human; D008869:Microtubule-Associated Proteins; D011810:Quinoxalines; C099718:SQSTM1 protein, human; D000071456:Sequestosome-1 Protein; D020169:Caspases
autophagy; dual modulation mechanisms; hypoxia-activated prodrug; posttranslational regulation; targeting treatment