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

Abstract

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.

• Authors: Inna Serganova, Ivan J Cohen, Kiranmayi Vemuri, Masahiro Shindo, Masatomo Maeda, Mayuresh Mane, Ekaterina Moroz, Raya Khanin, Jaya Satagopan, Jason A Koutcher, Ronald Blasberg
• Journal: PloS one (PLoS One) Vol. 13 Issue 9 Pg. e0203965 ( 2018) ISSN: 1932-6203 [Electronic] United States
• PMID: 30248111 (Publication Type: Journal Article, Research Support, N.I.H., Extramural, Research Support, Non-U.S. Gov't, Research Support, U.S. Gov't, Non-P.H.S.)

Chemical References

• Hif1a protein, mouse
• Hypoxia-Inducible Factor 1, alpha Subunit
• Isoenzymes
• Lactic Acid
• L-Lactate Dehydrogenase
• Lactate Dehydrogenase 5

Topics

• Animals
• Breast Neoplasms (metabolism, pathology)
• Cell Line, Tumor
• Female
• Gene Knockdown Techniques
• Humans
• Hypoxia-Inducible Factor 1, alpha Subunit (metabolism)
• Isoenzymes (antagonists & inhibitors, genetics, metabolism)
• L-Lactate Dehydrogenase (antagonists & inhibitors, genetics, metabolism)
• Lactate Dehydrogenase 5
• Lactic Acid (metabolism)
• Mammary Neoplasms, Experimental (immunology, metabolism, pathology)
• Mice
• Mice, Inbred BALB C
• Mice, Nude
• Neoplasm Metastasis (immunology, pathology)
• Neovascularization, Pathologic
• Signal Transduction
• Tumor Microenvironment (immunology, physiology)