Lactate oxidase/catalase-displaying nanoparticles efficiently consume lactate in the tumor microenvironment to effectively suppress tumor growth

<jats:title>Abstract</jats:title><jats:p>The aggressive proliferation of tumor cells often requires increased glucose uptake and excessive anaerobic glycolysis, leading to the massive production and secretion of lactate to form a unique tumor microenvironment (TME). Therefore, regulating appropriate lactate levels in the TME would be a promising approach to control tumor cell proliferation and immune suppression. To effectively consume lactate in the TME, lactate oxidase (LOX) and catalase (CAT) were displayed onto <jats:italic>Aquifex aeolicus</jats:italic> lumazine synthase protein nanoparticles (AaLS) to form either AaLS/LOX or AaLS/LOX/CAT. These complexes successfully consumed lactate produced by CT26 murine colon carcinoma cells under both normoxic and hypoxic conditions. Specifically, AaLS/LOX generated a large amount of H<jats:sub>2</jats:sub>O<jats:sub>2</jats:sub> with complete lactate consumption to induce drastic necrotic cell death regardless of culture condition. However, AaLS/LOX/CAT generated residual H<jats:sub>2</jats:sub>O<jats:sub>2</jats:sub>, leading to necrotic cell death only under hypoxic condition similar to the TME. While the local administration of AaLS/LOX to the tumor site resulted in mice death, that of AaLS/LOX/CAT significantly suppressed tumor growth without any severe side effects. AaLS/LOX/CAT effectively consumed lactate to produce adequate amounts of H<jats:sub>2</jats:sub>O<jats:sub>2</jats:sub> which sufficiently suppress tumor growth and adequately modulate the TME, transforming environments that are favorable to tumor suppressive neutrophils but adverse to tumor-supportive tumor-associated macrophages. Collectively, these findings showed that the modular functionalization of protein nanoparticles with multiple metabolic enzymes may offer the opportunity to develop new enzyme complex-based therapeutic tools that can modulate the TME by controlling cancer metabolism.</jats:p> <jats:p><jats:bold>Graphical Abstract</jats:bold></jats:p&gt

Lactate oxidase/vSIRP?? conjugates efficiently consume tumor-produced lactates and locally produce tumor-necrotic H2O2 to suppress tumor growth

Aggressive tumor formation often leads to excessive anaerobic glycolysis and massive production and accumu-lation of lactate in the tumor microenvironment (TME). To significantly curb lactate accumulation in TME, in this study, lactate oxidase (LOX) was used as a potential therapeutic enzyme and signal regulatory protein alpha variant (vSIRP alpha) as a tumor cell targeting ligand. SpyCatcher protein and SpyTag peptide were genetically fused to LOX and vSIRP alpha, respectively, to form SC-LOX and ST-vSIRP alpha and tumor-targeting LOX/vSIRP alpha conjugates were constructed via a SpyCatcher/SpyTag protein ligation system. LOX/vSIRP alpha conjugates selectively bound to the CD47-overexpressing mouse melanoma B16-F10 cells and effectively consumed lactate produced by the B16-F10 cells, generating adequate amounts of hydrogen peroxide (H2O2), which induces drastic necrotic tumor cell death. Local treatments of B16-F10 tumor-bearing mice with LOX/vSIRP alpha conjugates significantly suppressed B16-F10 tumor growth in vivo without any severe side effects. Tumor-targeting vSIRP alpha may allow longer retention of LOX in tumor sites, effectively consuming surrounding lactate in TME and locally generating adequate amounts of cytotoxic H2O2 to suppress tumor growth. The approach restraining the local lactate concentration and H2O2 in TME using LOX and vSIRP alpha could offer new opportunities for developing enzyme/ targeting ligand conjugate-based therapeutic tools for tumor treatment