Mechanism of itaconate mediated tumor suppression
The researchers in this study evaluated tumor-associated macrophages (TAMs) anti-tumor functions, especially focusing on the immune responsive gene 1 (IRG1) and its product, itaconate, in lung cancer development.
The researchers show that while the surrounding healthy lung tissue is rich in itaconate, the metabolite is drastically depleted within actual lung tumor regions to sustain rapid growth, restoring this pathway forces a severe metabolic crisis in cancer cells and shifts pro-tumor macrophages into defensive, anti-tumor engines.
In human and mouse lung tissue, Immune Responsive Gene 1 (IRG1)—the core enzyme responsible for turning the Krebs cycle intermediate cis-aconitate into itaconate—is exclusively expressed by macrophages.
To ensure unchecked proliferation, lung tumors downregulate or suppress this local pipeline, neutralizing the immune system's metabolic brakes. When researchers knocked out Irg1 or transplanted Irg1-depleted bone marrow into mice, lung tumor growth and metastasis accelerated dramatically.
Itaconate directly binds to and deactivates glucose-6-phosphate dehydrogenase (G6PD), the absolute rate-limiting enzyme of the oxidative pentose phosphate pathway. By locking G6PD, itaconate cuts off the PPP flux. This prevents cancer cells from manufacturing the carbon-based building blocks (like ribose-5-phosphate) and NADPH required to replicate their DNA and defend against oxidative stress, actively stopping cell division. Within the immune microenvironment, G6PD inhibition alters internal macrophage polarization. The severe drop in PPP energy generation forces pro-tumor, anti-inflammatory macrophages to transform into hyper-aggressive anti-tumor inflammatory defenders that actively attack the neighboring cancer mass.
The researchers proved that the membrane-permeable derivative 4-octyl itaconate (Octyl Ita) replicates this therapeutic behavior perfectly. Administering Octyl Ita successfully choked off tumor growth across in vitro lines, in vivo animal models, and ex vivo human precision-cut lung tumor slices.
https://www.cell.com/cell-metabolism/fulltext/S1550-4131(26)00190-7
