Exploring the role of LDH in cancer cells through the use of small-molecule inhibitors.

Metabolic reprogramming represents a potential therapeutic target in cancer. The studies of this thesis work lead to assume the enzyme lactate dehydrogenase (LDH) as key element coordinating neoplastic proliferation and invasive growth, suggesting for LDH inhibitor compounds a wider potential in anticancer treatment. The increased LDH-A expression has been observed in many tumor forms. In neoplastic cells, LDH commonly reduce pyruvate to lactate even in the presence of adequate oxygen supply (aerobic glycolysis). The rationale for targeting LDH activity in anticancer strategies is because LDH activity is not needed for pyruvate metabolism through the TCA cycle, thus, LDH inhibitors should spare glucose metabolism of normal cells. The objective of this work, simultaneously with the ongoing search for new LDH inhibitors, is the study of the role of LDH in cancer cells by pharmaceutical approach, through the use of inhibitors in different cell lines and conditions, and by genetic approach consisting in the depletion of LDH genes by the innovative CRISPR/Cas9 technology. By the use of two LDH inhibitors, oxamate and galloflavin, we demonstrated that LDH inhibition can impact on chemo-sensitivity, inflammation and heat shock response in cancer cell lines. The genetic knock-out of LDH enzyme evidenced that some cells are able to survive by switching their metabolism from glycolysis to OXPHOS, showing limited ability to grow and proliferate. Importantly, this genetic knock-out, used as control, allowed us to confirm the specificity of GNE-140 (LDH inhibitor) for the target, representing an important help in the search of LDH inhibitors suitable for clinical use, proved to be, in our studies, an important goal in the anti-cancer treatments.