Biological assays and genomic analysis reveal lipoic acid modulation of endothelial cell behavior and gene expression

Abstract

Lipoic acid (LA) is a sulfated antioxidant produced physiologically as a coenzyme of the pyruvate dehydrogenase complex; it is currently used for treatment of non-insulin-dependent diabetes to favor the cellular uptake of glucose. We have previously described the angiopreventive potential of molecules sharing common features with LA: N-acetyl cysteine, epigallocatechin-3-gallate and xanthohumol. To expand these studies, we have tested the capacity of LA to modulate angiogenesis in tumor growth using a Kaposi's sarcoma model. Endothelial cells exposed to LA displayed a dose-dependent reduction of cell migration and a time-dependent modulation of the phosphorylation of key signaling molecules. In vivo, LA efficiently repressed angiogenesis in matrigel plugs and KS-Imm tumor growth. We analyzed modulation of gene expression in endothelial cells treated with LA for 5 h (early response), finding a mild anti-apoptotic, antioxidant and anti-inflammatory response. A group of LA-targeted genes was selected to perform real-time polymerase chain reaction time-lapse experiments. The long-term gene regulation (48 h and 4 days) shows higher rates of modulation as compared with the array data, confirming that LA is able to switch the regulation of several genes linked to cell survival, inflammation and oxidative stress. LA induced the production of tumor necrosis factor-alpha-related apoptosis-inducing ligand (TRAIL) in KS-Imm and activin-A in KS-Imm and endothelial cells; these factors show anti-angiogenic activity in vivo contributing to explain the inhibitory effect of LA on neovascularization. According to our data, LA has promising anti-angiogenic properties, though its influence on central metabolic pathways should suggest more caution about its widespread and not prescribed use at pharmacological doses.

Is endothelial dysfunction of cerebral small vessel responsible for white matter lesions after chronic cerebral hypoperfusion in rats?

“…Biological assays and genomic analysis revealed that the antioxidant lipoic acid could modulate endothelial cell behavior and gene expression [35]. Lipoic acid can inhibit expression of ICAM-1 and VCAM-1 at the mRNA level in cultured human aortic endothelial cells [36].…”

Molecular Pathways for Cancer Angioprevention

“…A number of studies have also suggested a role for redoxdependent processes in the control of HIF-1 because treatment with diamide or hydrogen peroxide results in loss of DNA binding activity (26). Although transfection of the small redox protein thioredoxin-1 increases HIF-1a protein and activity and VEGF expression (27), lipoic acid treatment, which strongly increases thioredoxin reductase 1 expression, has antiangiogenic activities both in vitro and in vivo (28).…”

Inhibition of a vascular ocular tumor growth by IL-12 gene transfer

“…The primary antibodies used were a rabbit polyclonal anti-VEGF (Calbiochem, 1:50 dilution), and a polyclonal anti-asialo GM-1 (Wako Chemicals GmbH, 1:600 dilution). Staining with polyclonal anti-myeloperoxidase [14] and rat monoclonal CD31 [15] were as previously described. Sections were then lightly counter-stained with hematoxylin and mounted in glycergel.…”

“…Anti-asialo GM-1 positive NK cells were directly counted as the number of stained cells per highpower field. Vessels were identified and counted on the parental cell tumors with similar sizes having either pIRES (7) or IL-12 (5) expressing tumors controlaterally, using a previously described method [15] and the ImagePro-plus program to count vessel numbers and estimate average vessel area as well.…”