Galloflavin (CAS 568‐80‐9): A Novel Inhibitor of Lactate Dehydrogenase

Abstract

One of the most prominent alterations in cancer cells is their strict dependence on the glycolytic pathway for ATP generation. This observation led to the evaluation of glycolysis inhibitors as potential anticancer agents. The inhibition of lactate dehydrogenase (LDH) is a promising way to inhibit tumor cell glucose metabolism without affecting the energetic balance of normal tissues. However, the success of this approach depends chiefly on the availability of inhibitors that display good selectivity. We identified a compound (galloflavin, CAS 568-80-9) which, in contrast to other inhibitors of human LDH, hinders both the A and B isoforms of the enzyme. To determine the mechanism of action, we collected LDH-A and -B inhibition data in competition reactions with pyruvate or NADH and evaluated the results using software for enzyme kinetics analysis. We found that galloflavin inhibits both human LDH isoforms by preferentially binding the free enzyme, without competing with the substrate or cofactor. The calculated Ki values for pyruvate were 5.46 μM (LDH-A) and 15.06 μM (LDH-B). In cultured tumor cells, galloflavin blocked aerobic glycolysis at micromolar concentrations, did not interfere with cell respiration, and induced cell death by triggering apoptosis. To our knowledge, the inhibition of LDH is, to date, the only biochemical effect described for galloflavin. Because galloflavin is not commercially available, we also describe herein a procedure for its synthesis and report its first full chemical characterization.

Identification of LDH-A as a therapeutic target for cancer cell killing via (i) p53/NAD(H)-dependent and (ii) p53-independent pathways

“…Our results showing that suppressing LDH-A affects cancer cell SIRT1 activity are consistent with a recent study which reports that galloflavin, a novel inhibitor of both LDH isoforms (A and B), 36 reduces SIRT1 activity in Burkitt lymphoma cells. 37 …”

Pretreatment serum lactate dehydrogenase is an independent prognostic factor for patients receiving neoadjuvant chemotherapy for locally advanced cervical cancer

“…The result is in line with previous reports that showed LDH is a marker of response to NACT for breast cancer patients and oral cancer patients 23, 39. In vitro studies observed LDH is involved in resistance to chemotherapy, which may be an interpretation for the difference in CR rates by LDH levels 40, 41.…”

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.…”

“…By using structure-based virtual screening, a research team from the University of Bologna identified galloflavin (GF) (FiguRe 5B), a gallic acid derivative that inhibits both the A and B LDH isoforms [67]. The adopted virtual screening protocol was based on the crystal structure of the human M subunit of LDH, obtained from the Protein Data Bank [106].…”