Structural characterization of two isolectins from the marine red alga Solieria filiformis (Kützing) P.W. Gabrielson and their anticancer effect on MCF-7 breast cancer cells

Abstract

As described in the literature, Solieria filiformis lectin (SfL) from the marine red alga S. filiformis was found to have antinociceptive and anti-inflammatory effects. In this study, we characterized two SfL variants, SfL-1 and SfL-2, with molecular mass of 27,552Da and 27,985Da, respectively. The primary structures of SfL-1 and SfL-2 consist of four tandem-repeat protein domains with 67 amino acids each. SfL-1 and -2 showed high similarity to OAAH-family lectins. 3D structure prediction revealed that SfL-1 and -2 are composed of two β-barrel-like domains formed by five antiparallel β-strands, which are connected by a short peptide linker. Furthermore, the mixture of isoforms (SfLs) showed anticancer effect against MCF-7 cells. Specifically, SfLs inhibited 50% of viability in MCF-7 cells after treatment at 125μg.mL, while the inhibition of Human Dermal Fibroblasts (HDF) was 34% with the same treatment. Finally, 24h after treatment, 25% of MCF-7 cells were in early apoptosis and 35% in late apoptosis. Evaluation of pro- and anti-apoptotic gene expression of MCF-7 cells revealed that SfLs induced caspase-dependent apoptosis within 24h.

Lectins from red algae and their biomedical potential

“…In a direct binding experiment with pyridylaminated oligosaccharides, an isolectin EDA-2 exclusively binds to high-mannose type N-glycans but not to other glycans that include complex types and a core pentasaccharide of N-glycans, indicating that it recognises the branched oligomannoside moiety (Hung et al 2015). Molecular docking calculations and favourable binding energies reveal that purified isolectins (SfL-1 and SfL-2) from S. filiformis specifically bind to 3α,6α mannopentose oligosaccharides, thus exhibits specificity towards highmannose oligosaccharides (Chaves et al 2017).…”

“…Tichocarpus crinitus lectin has been purified by phenyl-Sepharose hydrophobic chromatography and gel exclusion chromatography (Molchanova et al 2010). Recently, isolectins from S. filiformis have been purified by DEAE-Sephacel ion exchange chromatography (Chaves et al 2017).…”

“…Lectin from A. callophyllidicola is dimeric with subunits having molecular weights of 50 and 14 kDa (Shim et al 2012). Isolectins, SfL-1 and SfL-2, from S. filiformis have a molecular mass of 27,552 and 27,985 Da, respectively (Chaves et al 2017).…”

“…Similar to native KAA lectin, His-tagged rKAA-1 and rKAA-1 specifically bind to high-mannose N-glycans with an exposed α1-3 mannose in the D2 arm as revealed by oligosaccharide binding analysis by a centrifugal ultrafiltration-HPLC method with 27 pyridylaminated oligosaccharides (Hirayama et al 2016). Primary structure of two isolectins from S. filiformis (SfL-1 and SfL-2) consisting of four tandem-repeat domains with approximately 67 amino acids has been recently determined (Chaves et al 2017). Both isolectins exhibit 82% sequence identity towards each other and are composed of two β barrel-like domains formed by five anti-parallel β-strands, which are connected by a short peptide linker (Chaves et al 2017).…”

“…Owing to high expression level, potency, stability and current indication for topical delivery, GRFT acts as best-case scenario for non-vaccine plant made pharmaceuticals; however, there are many challenges associated with its bulk production (Fuqua et al 2015). Lectins from various other red marine algae such as Eucheuma serra (Fukuda et al 2006), Bryothamnion seaforthii and Bryothamnion triquetrum (Pinto et al 2009), Acrocystis nana (Anam et al 2017a(Anam et al , 2017b and Solieria filiformis (Chaves et al 2017) have anti-cancer potential and also used as drug delivery agents owing to their carbohydrate specificity. Thus, studies conducted on various algal lectins bring in a new element of research in biomedical applications.…”