Tetra-O-methyl-nordihydroguaiaretic acid inhibits energy metabolism and synergistically induces anticancer effects with temozolomide on LN229 glioblastoma tumors implanted in mice while preventing obesity in normal mice that consume high-fat diets

Abstract

Tetra-O-methyl-nordihydroguaiaretic acid (terameprocol; M4N), a global transcription inhibitor, in combination with a second anticancer drug induces strong tumoricidal activity and has the ability to suppress energy metabolism in cultured cancer cells. In this study, we showed that after continuous oral consumption of high-fat (HF) diets containing M4N, the M4N concentration in most of the organs in mice reached ~1 μM (the M4N concentration in intestines and fat pads was as high as 20–40 μM) and treatment with the combination of M4N with temozolomide (TMZ) suppressed glycolysis and the tricarboxylic acid cycle in LN229 human glioblastoma implanted in xenograft mice. Combination treatment of M4N with TMZ also reduced the levels of lactate dehydrogenase A (LDHA), a key enzyme for glycolysis; lactate, a product of LDHA-mediated enzymatic activity; nicotinamide phosphoribosyltransferase, a rate-limiting enzyme for nicotinamide adenine dinucleotide plus hydrogen (NADH)/NAD+ salvage pathway; and NAD+, a redox electron carrier essential for energy metabolism. It was also shown that M4N suppressed oxygen consumption in cultured LN229 cells, indicating that M4N inhibited oxidative phosphorylation. Treatment with M4N and TMZ also decreased the level of hypoxia-inducible factor 1A, a major regulator of LDHA, under hypoxic conditions. The ability of M4N to suppress energy metabolism resulted in induction of the stress-related proteins activating transcription factor 4 and cation transport regulator-like protein 1, and an increase in reactive oxygen species production. In addition, the combination treatment of M4N with TMZ reduced the levels of oncometabolites such as 2-hydroxyglutarate as well as the aforementioned lactate. M4N also induced methylidenesuccinic acid (itaconate), a macrophage-specific metabolite with anti-inflammatory activity, in tumor microenvironments. Meanwhile, the ability of M4N to suppress energy metabolism prevented obesity in mice consuming HF diets, indicating that M4N has beneficial effects on normal tissues. The dual ability of combination treatment with M4N to suppress both energy metabolism and oncometabolites shows that it is potentially an effective therapy for cancer.

Interaction and Collaboration of SP1, HIF-1, and MYC in Regulating the Expression of Cancer-Related Genes to Further Enhance Anticancer Drug Development

“…The function of these proteins as well as energy metabolism are associated with the activities of SP1 and HIF-1 [34,[38][39][40][41][42][43][44]. M 4 N can markedly induce cellular stress in cancer cells [163,169]. The activity of SP1 and HIF-1 in protecting cells from cellular stress has been previously described [72][73][74], and thus M 4 N as an SP1 and HIF-1 dual inhibitor likely suppresses this activity.…”

“…Tetramethyl-O-nordihydroguaiaretic acid (M 4 N) is an anticancer drug candidate that has been studied for many years [156][157][158][159][160][161][162][163][164][165][166][167][168][169][170][171][172]. This compound reversibly inhibits the binding of SP1 to its DNA consensus sequence thereby functioning as an SP1 inhibitor unlike mithramycin which is an irreversible inhibitor of SP1 [156].…”

“…Importantly, M 4 N essentially has no strong side effects [171], suggesting that the reversible inhibition of SP1 and HIF1A bindings to their target genes might not cause strong toxicity. M 4 N also downregulates the expression of proteins, such as B-cell lymphoma 2/adenovirus E1B 19kDa protein-interacting protein 3, X-linked inhibitor of apoptosis protein, survivin, VEGF, and lactate dehydrogenase A [161,163,164,169,170], and suppresses energy metabolism [162,168]. The function of these proteins as well as energy metabolism are associated with the activities of SP1 and HIF-1 [34,[38][39][40][41][42][43][44].…”

“…The activity of SP1 and HIF-1 in protecting cells from cellular stress has been previously described [72][73][74], and thus M 4 N as an SP1 and HIF-1 dual inhibitor likely suppresses this activity. However, the stress induced by M 4 N does not seem to be strong enough to induce significant tumoricidal activity, as M 4 N treatment alone has not been shown to induce anticancer activity strong enough to eliminate cancer (although it slows cancer growth) in various xenograft mice and many patients [163,165,166,169,171]. The most compelling data showing the efficacy of M 4 N as an anticancer drug is a clinical trial that was conducted in India in the 1990s treating patients with oral squamous cell carcinoma [172].…”

“…However, it might be sufficient to make cancer cells vulnerable against a second anticancer drug that is able to induce strong cytocidal effects, as shown by the synergistic induction of anticancer activity with the combination treatment of M 4 N with a second anticancer drug in various xenograft mouse experiments [163,165,166,169]. It was also shown that combination treatment with M 4 N suppresses energy metabolism and oncometabolites in addition to inducing strong cellular stress, making it a potentially impressive anticancer treatment [163,169]. In addition, M 4 N induces interleukin 21 and enhances B cell-mediated humoral immunity in tumor-bearing mice [173].…”