Issue 11, 2009

Tumor-specific protein human galectin-1 interacts with anticancer agents

Abstract

The present work shows a novel binding activity of the tumor specific lectin—recombinant human galectin-1 (hGal-1)—to three porphyrin compounds: (1) Zn-porphyrin (ZnTPPS); (2) Mn-porphyrin and (3) Au-porphyrin. These compounds are widely applied in the photodynamic therapy of cancer (PDT). Our data indicate that hGal-1, similar to some plant lectins, a bacterial lectin from Pseudomonas aeruginosa and an animal lectin from Helix pomatia, possesses dual functions binding to both carbohydrate and non-carbohydrate ligands. The interaction of ZnTPPS with hGal-1 was studied by the specific fluorescence emission of the porphyrin. The protein binding properties to Mn/Au-porphyrins and adenine were measured by intrinsic protein fluorescence quenching. The values determined for the apparent dissociation constants (KD) of 0.6–1.5 μM are similar to the KD for complexes of concanavalin A and porphyrin, and are indicative of the high affinity of hGal-1 for these porphyrins. In addition, the analysis of the hyperbolic binding curves obtained suggests the presence of one hGal-1 binding site for porphyrins or adenine. Additionally, we found that hGal-1 interacts with the fluorescent probe 2-(p-toluidinyl)naphthalene sulfonic acid (TNS), that was used to identify the hydrophobic regions within hGal-1. Homodimeric hGal-1 has more than one class of binding site for TNS as revealed by the sigmoidal shape of the fluorescence titration curve. hGal-1 can be characterized as a porphyrin-bindingprotein based on its interactions with the Zn/Mn- and Au-porphyrins, and this indicates that hGal-1 may have potential as a delivery molecule to target systems (e.g., tumor cells) with possible application in photodynamic therapy.

Graphical abstract: Tumor-specific protein human galectin-1 interacts with anticancer agents

Article information

Article type
Paper
Submitted
25 Mar 2009
Accepted
29 Jul 2009
First published
18 Aug 2009

Mol. BioSyst., 2009,5, 1331-1336

Tumor-specific protein human galectin-1 interacts with anticancer agents

S. D’Auria, L. Petrova, C. John, G. Russev, A. Varriale and V. Bogoeva, Mol. BioSyst., 2009, 5, 1331 DOI: 10.1039/B905921K

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