First-in-class ruthenium anticancer drug (KP1339/IT-139) induces an immunogenic cell death signature in colorectal spheroids in vitro

Abstract

The ruthenium complex sodium trans-[tetrachloridobis(1H-indazole)ruthenate(III)] (KP1339/IT-139) showed preclinical activity in a variety of in vivo tumor models including a highly predictive colon cancer model. The compound has entered clinical trials, where patients experienced disease stabilization accompanied by mild side effects.KP1339, a GRP78 inhibitor, disrupts endoplasmic reticulum (ER) homeostasis leading to cell death. The PERK/eIF2a-branch of the ER plays an essential role in the cascade of events triggering immunogenic cell death (ICD). ICD makes dying cancer cells 'visible' to the immune system, initiating a prolonged immune response against the tumor. As some metal-based chemotherapeutics such as oxaliplatin are able to induce ICD, we investigate whether KP1339 could also trigger induction of the ICD signature. For this, we employ a three-dimensional colon cancer spheroid model and show for the first time that the treatment with KP1339, a ruthenium-based complex, triggers an ICD signature hallmarked by phosphorylation of PERK and eIF2a, exposure of calreticulin on the cell membrane, release of high mobility group box 1 and secretion of ATP. Significance to metallomicsThe impact of metal-based compounds on the immunological aspects of cancer is now emerging as a critical component of their therapeutic potential. It has been demonstrated based on preclinical and clinical data, that the immunomodulatory effects of platinum complexes provide a promising platform for their combination with immunotherapies. However, further studies are necessary to elucidate the complex interaction between cancer and the immune system and the role of metal-based drugs in modulating their intricate interplay. Our work highlights the importance of studying the immunological aspects of metal-based compounds, and emphasizes the potential of rutheniumderived complexes in this emerging field. Metallomics COMMUNICATION

Single Spheroid Metabolomics: Optimizing Sample Preparation of Three-Dimensional Multicellular Tumor Spheroids

“…In this work, we could individuate the impact on biochemical pathways related to redox stress: glutathione metabolism (glutathione, oxidized glutathione and NADP+ are up-, glutamate down-regulated), purine metabolism, pentose phosphate pathway (ribulose 5-phosphate/ribose 5-phosphate down-regulated), which could be explained by the hypothesized reduction of the drug. Redox stress and elevation of ROS protective proteins [42,50] were confirmed by previous proteomics studies. Finally, pathways such as glycerophospholipid metabolism (strong choline down-regulation) and various amino acid metabolism-related pathways were pinpointed (glutamine and glutamate metabolism, alanine, aspartate and glutamate metabolism, arginine biosynthesis).…”

“…There are indications that this drug is a GRP78 inhibitor, an ER stress sensing chaperone [39,49]. It not only induces ER stress and unfolded protein response, but it has also been shown that it exhibits the hallmarks of immunogenic cell death, calreticulin exposure, and ATP secretion among others [42]. Less is known about the metabolic effects of this compound.…”

“…Furthermore, KP1339 shows a prodrug nature, as it is thought to be preferentially reduced in the more reductive milieu of solid tumors to the active Ru(II) form. Finally, while oxaliplatin is considered a bona fide immunogenic cell death inducer [40], KP1339 also exhibits the hallmarks of immunogenic cell death [41,42].…”

Inhibition of DNA Repair Pathways and Induction of ROS Are Potential Mechanisms of Action of the Small Molecule Inhibitor BOLD-100 in Breast Cancer

“…BOLD-100 is a novel small molecule that showed modest anti-tumor activity in a Phase I clinical trial [12]. Mechanistically, BOLD-100 has been shown to down-regulate GRP78 in thapsigargin-mediated stressed cancer cells [15] and trigger immunogenic cell death through the PERK/EIF2a branch of the UPR accompanied by ROS production, release of high mobility group box 1 (HMGB1) and ATP secretion via autophagy [31]. Sensitivity toBOLD-100 can vary in different cells and cellular responses including cell cycle (via G2 cell cycle arrest), DNA repair pathway, and cellular metabolism are known to be affected [17].…”

Immunogenic cell death in colon cancer prevention and therapy

“…Bortezomib is a specific inhibitor of the 26S proteasome subunit and induces apoptosis of various cancer cells, associated with enhanced phagocytosis and DC cross‐presentation of tumor antigens to T cells 116 . In preclinical CRC models, bortezomib, HSP inhibitors, mTOR/PI3K inhibitors, BET inhibitors or a GRP78 inhibitor induced ER stress‐associated cell death 85‐90 . Interestingly, several drug combinations were particularly effective in killing CRCs harboring mutant KRAS/BRAF or SPOP through elevated ER stress and DR5 expression 91,92 .…”