LDH-A inhibition, a therapeutic strategy for treatment of hereditary leiomyomatosis and renal cell cancer

Abstract

The genetic basis for the hereditary leiomyomatosis and renal cell cancer syndrome is germ-line inactivating mutation in the gene for the Krebs/tricarboxylic acid cycle enzyme, fumarate hydratase (FH), the enzyme that converts fumarate to malate. These individuals are predisposed to development of leiomyomas of the skin and uterus as well as highly aggressive kidney cancers. Inhibition of FH should result in significant decrease in oxidative phosphorylation necessitating that glycolysis followed by fermentation of pyruvate to lactate will be required to provide adequate ATP as well as to regenerate NAD + . Moreover, FH deficiency is known to up-regulate expression of hypoxia-inducible factor (HIF)-1A by enhancing the stability of HIF transcript. This leads to activation of various HIF-regulated genes including vascular endothelial growth factor and glucose transporter GLUT1 and increased expression of several glycolytic enzymes. Because lactate dehydrogenase-A (LDH-A), also a HIF-1A target, promotes fermentative glycolysis (conversion of pyruvate to lactate), a step essential for regenerating NAD + , we asked whether FH-deficient cells would be exquisitely sensitive to LDH-A blockade. Here, we report that hereditary leiomyomatosis and renal cell cancer tumors indeed overexpress LDH-A, that LDH-A inhibition results in increased apoptosis in a cell with FH deficiency and that this effect is reactive oxygen species mediated, and that LDH-A knockdown in the background of FH knockdown results in significant reduction in tumor growth in a xenograft mouse model. [Mol Cancer Ther 2009;8(3):626 -35]

Inhibition of lactate dehydrogenase A induces oxidative stress and inhibits tumor progression

“…Here, we document that LDHA inhibition, which was previously shown through genetically engineered cells to reduce tumor initiation (16,17), not only resulted in decreased ATP levels and reduced mitochondrial membrane potential but in a remarkable increase in oxidative stress that is linked to cell death. Furthermore, inhibition of LDHA by FX11 inhibited tumor xenograft progression, confirming that LDHA is required for tumor maintenance.…”

“…Studies now document that reduction of LDHA reduced cellular transformation and markedly delayed tumor formation, indicating that LDHA is important for tumor initiation (16,17). These studies provide proof-of-concept that LDHA is a tractable therapeutical target but do not establish whether LDHA is required for tumor progression.…”

Tumor-Derived Lactate Modifies Antitumor Immune Response: Effect on Myeloid-Derived Suppressor Cells and NK Cells

“…Pan02 cells were infected with an empty shRNA vector control and three different LDH-A shRNA lentiviruses as described previously (4). Western blot analysis with anti-LDH-A Ab (Fig.…”

“…To develop a LDH-A-negative tumor cell line, LDH gene expression was knocked down in the cell line Pan02 as follows: Pan02 cells were infected with an empty short hairpin RNA (shRNA) vector control and three different LDH-A shRNAs lentiviruses as described previously. Briefly, recombinant lentiviruses were produced by transient transfection of 293T cells according to a standard protocol (4). Pan02 cells were treated with the above cell culture supernatant containing lentiviral particles for 24 h. These cells were then selected in puromycin to generate stable cell lines encoding empty vector shRNA and LDH-A shRNA.…”

“…Growing tumor cells develop strategies to overcome host immune surveillance. One of the strategies used by tumor cells is to change their microenvironment by the release of lactate, an important side product of tumor metabolism (3)(4)(5). Well-characterized immunosuppressive mechanisms include suppressor cells (regulatory T cells [Tregs], myeloid-derived suppressor cells [MDSCs], and M2-polarized macrophages) that infiltrate the tumor environment as well as numerous cytokines such as TGF-b, and IL-10 among others (6).…”