Lactate Dehydrogenase Isoenzymes 1 and 5: Differential Expression by Neoplastic and Stromal Cells in Non-Small Cell Lung Cancer and Other Epithelial Malignant Tumors
2003; SAGE Publishing; Volume: 24; Issue: 4 Linguagem: Inglês
10.1159/000074430
ISSN1423-0380
AutoresMichael I. Koukourakis, Alexandra Giatromanolaki, Efthimios Sivridis,
Tópico(s)Metabolomics and Mass Spectrometry Studies
ResumoLactate dehydrogenase-5 (LDH-5), an isoenzyme composed of 4 M-polypeptide chains, catalyzes the conversion of pyruvate to lactate with an unparalleled efficiency (anaerobic oxidation), but this function of LDH gradually fades away as the number of H over M chains increases. Thus, LDH-1, another component isoenzyme made up of 4 H-polypeptide chains, favors aerobic oxidation of pyruvate by pyruvate dehydrogenase.Using immunohistochemistry in this study, we explored the expression of LDH-1 and LDH-5 in a variety of normal and malignant tissues, including lung, breast, endometrium, urinary bladder and large intestine.LDH-1 was consistently expressed in all living cells, normal and malignant, epithelial and stromal, including endothelium and lymphocytes. In contrast, LDH-5 was expressed preferentially in tumor cells, while normal tissues were devoid of LDH-5 or expressed it only faintly, and the cellular population of the tumor-supporting stroma showed LDH-5 activity in a small percentage of cases. Interestingly, LDH-5-positive stromal cells were associated with hypoxia-inducible factor-1alpha overexpression.It is concluded that normal tissues utilize aerobic oxidation as a means of energy production, while tumor cells are turned to anaerobic glycolysis, a phenomenon which is rarely followed by the mesenchymal cells of the tumor-supporting stroma.
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