Multifunctional antitumor molecule 5'-triphosphate siRNA combining glutaminase silencing and RIG-I activation.

Abstract

Resisting cell death, reprogrammed metabolism and immune escape are fundamental traits of hard-to-treat cancers. Therapeutic improvement can be expected by designing drugs targeting all three aspects. 5'-Triphosphate RNA (ppp-RNA), a specific ligand of the pattern recognition receptor retinoic acid-inducible gene I (RIG-I), has been shown to trigger intrinsic apoptosis of malignant cells and to activate antitumor immune responses via type I interferons (IFNs). In our study, we designed a ppp-modified siRNA specifically silencing glutaminase (ppp-GLS), a key enzyme of glutaminolysis that is indispensable for many cancer types. Bifunctional ppp-GLS induced more prominent antitumor responses than RNA molecules that contained either the RIG-I ligand motif or GLS silencing capability alone. The cytopathic effect was constrained to tumor cells as nonmalignant cells were not affected. We then analyzed the mechanisms leading to the profound antitumor efficacy. First, ppp-GLS effectively induced intrinsic proapoptotic signaling. In addition, GLS silencing sensitized malignant cells to RIG-I-induced apoptosis. Moreover, disturbed glutaminolysis by GLS silencing contributed to enhanced cytotoxicity. Finally, RIG-I activation blocked autophagic degradation leading to dysfunctional mitochondria and reactive oxygen species (ROS) generation, whereas GLS silencing severely impaired ROS scavenging systems, leading to a vicious circle of ROS-mediated cytotoxicity. Taken together, ppp-GLS combines cell death induction, immune activation and glutaminase inhibition in a single molecule and has high therapeutic efficacy against cancer cells.

• Authors: Gang Meng, Mao Xia, Chun Xu, Dongmei Yuan, Max Schnurr, Jiwu Wei
• Journal: International journal of cancer (Int J Cancer) Vol. 134 Issue 8 Pg. 1958-71 (Apr 15 2014) ISSN: 1097-0215 [Electronic] United States
• PMID: 23921958 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)
• Copyright: © 2013 UICC.

Chemical References

• RNA, Small Interfering
• Reactive Oxygen Species
• Receptors, Immunologic
• Glutaminase
• DDX58 protein, human
• DEAD Box Protein 58
• DEAD-box RNA Helicases

Topics

• Apoptosis (drug effects)
• Cell Line, Tumor
• Cell Survival
• DEAD Box Protein 58
• DEAD-box RNA Helicases (genetics, metabolism)
• Enzyme Activation
• Female
• Glioma (drug therapy)
• Glutaminase (antagonists & inhibitors, genetics)
• HeLa Cells
• Humans
• Lung Neoplasms (drug therapy)
• Mitochondria (drug effects, metabolism)
• Neoplasms (drug therapy)
• Pancreatic Neoplasms (drug therapy)
• RNA Interference
• RNA, Small Interfering (pharmacology)
• Reactive Oxygen Species (metabolism)
• Receptors, Immunologic
• Uterine Cervical Neoplasms (drug therapy)