LDH-A regulates the tumor microenvironment via HIF-signaling and modulates the immune response

• Published in: PloS one 2018-09, Vol.13 (9), p.e0203965-e0203965
• Main Authors: Serganova, Inna, Cohen, Ivan J, Vemuri, Kiranmayi, Shindo, Masahiro, Maeda, Masatomo, Mane, Mayuresh, Moroz, Ekaterina, Khanin, Raya, Satagopan, Jaya, Koutcher, Jason A, Blasberg, Ronald
• Format: Article
• Language: English
• Subjects: Angiogenesis; Animals; Biology and Life Sciences; Bioluminescence; Breast cancer; Breast Neoplasms - metabolism; Breast Neoplasms - pathology; Cancer; Care and treatment; CD3 antigen; CD4 antigen; Cell Line, Tumor; Cloning; Computer simulation; Dehydrogenases; Development and progression; Female; Gangrene; Gene expression; Gene Knockdown Techniques; Genes; Genetic aspects; Glycolysis; Hexokinase; Humans; Hypoxia; Hypoxia-Inducible Factor 1, alpha Subunit - metabolism; Immune response; Immune system; Infiltration; Isoenzymes - antagonists & inhibitors; Isoenzymes - genetics; Isoenzymes - metabolism; L-Lactate Dehydrogenase - antagonists & inhibitors; L-Lactate Dehydrogenase - genetics; L-Lactate Dehydrogenase - metabolism; Lactic acid; Lactic Acid - metabolism; Lymphocytes; Lymphocytes T; Mammary Neoplasms, Experimental - immunology; Mammary Neoplasms, Experimental - metabolism; Mammary Neoplasms, Experimental - pathology; Medical prognosis; Medical research; Medicine and Health Sciences; Metabolism; Metabolites; Metastases; Metastasis; Mice; Mice, Inbred BALB C; Mice, Nude; Necrosis; Neoplasm Metastasis - immunology; Neoplasm Metastasis - pathology; Neovascularization, Pathologic; Neurology; Phenotypes; Plasmids; Regulatory sequences; Research and Analysis Methods; Signal Transduction; Surgery; Tumor Microenvironment - immunology; Tumor Microenvironment - physiology; Tumors; Vascular endothelial growth factor; Vascularization
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0203965

Previous studies show that LDH-A knockdown reduces orthotopic 4T1 breast tumor lactate and delays tumor growth and the development of metastases in nude mice. Here, we report significant changes in the tumor microenvironment (TME) and a more robust anti-tumor response in immune competent BALB/c mice. 4T1 murine breast cancer cells were transfected with shRNA plasmids directed against LDH-A (KD) or a scrambled control plasmid (NC). Cells were also transduced with dual luciferase-based reporter systems to monitor HIF-1 activity and the development of metastases by bioluminescence imaging, using HRE-sensitive and constitutive promoters, respectively. The growth and metastatic profile of orthotopic 4T1 tumors developed from these cell lines were compared and a primary tumor resection model was studied to simulate the clinical management of breast cancer. Primary tumor growth, metastasis formation and TME phenotype were significantly different in LDH-A KD tumors compared with controls. In LDH-A KD cells, HIF-1 activity, hexokinase 1 and 2 expression and VEGF secretion were reduced. Differences in the TME included lower HIF-1α expression that correlated with lower vascularity and pimonidazole staining, higher infiltration of CD3+ and CD4+ T cells and less infiltration of TAMs. These changes resulted in a greater delay in metastases formation and 40% long-term survivors (>20 weeks) in the LDH-A KD cohort following surgical resection of the primary tumor. We show for the first time that LDH-depletion inhibits the formation of metastases and prolongs survival of mice through changes in tumor microenvironment that modulate the immune response. We attribute these effects to diminished HIF-1 activity, vascularization, necrosis formation and immune suppression in immune competent animals. Gene-expression analyses from four human breast cancer datasets are consistent with these results, and further demonstrate the link between glycolysis and immune suppression in breast cancer.