Fragment Growing and Linking Lead to Novel Nanomolar Lactate Dehydrogenase Inhibitors

Abstract

Lactate dehydrogenase A (LDH-A) catalyzes the interconversion of lactate and pyruvate in the glycolysis pathway. Cancer cells rely heavily on glycolysis instead of oxidative phosphorylation to generate ATP, a phenomenon known as the Warburg effect. The inhibition of LDH-A by small molecules is therefore of interest for potential cancer treatments. We describe the identification and optimization of LDH-A inhibitors by fragment-based drug discovery. We applied ligand based NMR screening to identify low affinity fragments binding to LDH-A. The dissociation constants (K(d)) and enzyme inhibition (IC(50)) of fragment hits were measured by surface plasmon resonance (SPR) and enzyme assays, respectively. The binding modes of selected fragments were investigated by X-ray crystallography. Fragment growing and linking, followed by chemical optimization, resulted in nanomolar LDH-A inhibitors that demonstrated stoichiometric binding to LDH-A. Selected molecules inhibited lactate production in cells, suggesting target-specific inhibition in cancer cell lines.

Lactate dehydrogenase 5: An old friend and a new hope in the war on cancer

“…At present, every month brings new information on novel LDH-5 inhibitors that are being actively identified, designed and synthesized [92][93][94]. Therefore, it can be expected that anti-LDH-5 drugs will soon be successfully developed for clinical use.…”

Inhibition of Lactate Dehydrogenase Activity as an Approach to Cancer Therapy

“…In the field of cancer metabolic inhibitors, LDH is considered one of the most promising therapeutic targets; its inhibition as an approach to anticancer was proposed several years ago [65,66] and is currently under active investigation [67][68][69][70][71]. Interest in LDH as an anticancer therapeutic target comes from the observation that this enzyme (namely its -A isoform) becomes constantly up regulated during neoplastic change [49][50][51]54], offering the possibility of a therapeutic intervention aimed at correcting this altered activity.…”

“…This compound also proved to be active in vivo, on mice with tumor xenografts administered at the daily dose of 42 µg. However, further studies have challenged the validity of FX-11, giving rise to the suspicion that some of the observed effects could be not specifically ascribed to LDH inhibition, but to the reactive nature of the catechol group of the molecule [70,102]. FX-11 was not tested in clinical trials; on the contrary, the parental molecule gossypol, which, as stated above, is a weaker LDH inhibitor and displays a multiplicity of effects, entered some Phase I/II clinical trials.…”

Synthesis and biological evaluation of N-hydroxybenzimidazoles as potential anticancer agents targeting human lactate dehydrogenase A

“…over-expressed in human tumor tissues [15]. In addition, small hairpin RNA-meditated knock-down of LDHA in tumor cells induced a decrease in cell proliferation [16][17][18]. These observations indicate that LDHA can be an attractive target for inhibiting tumor proliferation [19][20][21][22].…”