# Effects of Acidic Polysaccharide-Enriched Extracts from Holothuria tubulosa on Two- and Three-Dimensional Invasive Breast Cancer Cell Models

## TL;DR

This study explores how acidic polysaccharides from sea cucumbers may inhibit breast cancer cell growth and migration, suggesting potential anticancer properties.

## Contribution

The novel contribution is the identification of antitumor effects of less sulfated polysaccharide fractions from Holothuria tubulosa on invasive breast cancer cells.

## Key findings

- Treatment with Ht1 reduced cell migration and increased adhesion on collagen I.
- Ht1 upregulated E-cadherin, while Ht2 modulated matrix metalloproteinases 7 and 9.
- AP fractions decreased cell viability but had limited effects on three-dimensional spheroids.

## Abstract

Holothurians represent a rich source of bioactive compounds with potential applications in pharmaceutics. We recently described interesting inhibitory properties on both the intrinsic and extrinsic coagulation pathways of the acid polysaccharides component extracted from the body wall of the species Holothuria tubulosa. The highly sulphated fractions, mainly consisting of a fucosylated chondroitin sulfate, were the most active. In this study, we assessed the effects of the less sulphated polysaccharide fractions on MDA-MB-231 cells, a highly metastatic triple-negative breast cancer cell line. Specifically, the effects on cell metabolic activity, migratory behaviour, and the expression of key genes implicated in tumor progression were evaluated. Furthermore, a qualitative assessment of the morphology of three-dimensional tumor spheroids was performed. The findings suggest that these fractions may exert antitumor effects by reducing the metabolic activity and migratory potential of MDA-MB-231 cells.

Marine invertebrates, particularly Holothurians, have emerged as valuable sources of bioactive compounds with potential anticancer properties. In this study, we investigated the effects of two acidic polysaccharide-enriched (APs) fractions (Ht1 and Ht2) from the sea cucumber species Holothuria tubulosa on the highly invasive cell line MDA-MB-231. Functional assays were performed to assess cell viability, migratory potential, adhesion on collagen I, and cell morphology, alongside gene expression analysis. Additionally, a preliminary evaluation of their effects on three-dimensional breast cancer cell-derived spheroids was conducted. Both AP fractions exerted anticancer effects by decreasing cell viability. Ht1 showed a significant inhibitory effect on cell migration, increased adhesion on collagen I, and exhibited a trend to transform the mesenchymal MDA-MB-231 cells to a more epithelial phenotype. Treatment with the AP fractions modulated the expression of genes, such as the epithelial marker E-cadherin (for the Ht1), a key cell adhesion molecule, and the matrix metalloproteinases 7 and 9 (for the Ht2), enzymes involved in extracellular matrix remodeling, which hold critical roles in cancer progression and metastasis. No significant effects were observed on spheroids, possibly due to the high charge and hydrophilicity of the APs, leading to poor penetration into the inner spheroid layers. Although preliminary, these findings highlight the potential of H. tubulosa-derived APs as promising antineoplastic agents, warranting further investigation into their mechanisms of action and structural characterization.