Holothuria scabra Extract Induces Cell Apoptosis and Suppresses Warburg Effect by Down-Regulating Akt/mTOR/HIF-1 Axis in MDA-MB-231 Breast Cancer Cells

INTRODUCTION

Cancer cells utilize the modified glucose metabolism known as Warburg effect, with lactate production as the end product. In the search for alternative therapy, the body wall of sea cucumbers contains various substances with pharmacological activities. Herein, we investigate the effect of Holothuria scabra extract on the viability and Warburg effect of aggressive breast cancer cells.

METHODS

Body wall of H. scabra was extracted using 95% ethanol. Triple-negative breast cancer cells, MDA-MB-231, were treated with the extract at various concentrations under normoglycemic and hyperglycemic conditions. Cytotoxicity test was performed using MTT assay. Apoptotic proteins were quantified using Western blot. Apoptotic cells were stained with Hoechst 33342. Lactate production was determined using L-lactate assay kit.

RESULTS

By MTT assay, H. scabra extract suppressed the viability of breast cancer cells in a dose-dependent and time-dependent manner by enhancing apoptosis, indicated by a marked increase of proapoptotic Bax and pro-caspase three expressions, and decreased expression of anti-apoptotic Bcl-2. The extract could reduce hexokinase II expression, leading to reduced lactate production by blocking the Akt/mTOR/HIF-1 axis.

DISCUSSION

Overall findings indicated that H. scabra extract could be a possible therapeutic against breast cancer progression in patients with hyperglycemia, for instance, diabetes mellitus.

Cytoprotective Effects of Lysophospholipids from Sea Cucumber Holothuria atra

Lysophospholipids are important signaling molecules in animals and metazoan cells. They are widely distributed among marine invertebrates, where their physiological roles are unknown. Sea cucumbers produce unique lysophospholipids. In this study, two lysophospholipids were detected in Holothuria atra for the first time, lyso-platelet activating factor and lysophosphatidylcholine, with nuclear magnetic resonance and liquid chromatography-time-of-flight mass spectrometric analyses. The lipid fraction of H. atra contained lyso-platelet activating factor and lysophosphatidylcholine, and inhibited H2O2-induced apoptosis in the macrophage cell line J774A.1. The antioxidant activity of the lysophospholipid-containing lipid fraction of H. atra was confirmed with the oxygen radical absorbance capacity method. Our results suggest that the lysophospholipids from H. atra are potential therapeutic agents for the inflammation induced by oxidative stress.

Sea Cucumbers Metabolites as Potent Anti-Cancer Agents

Sea cucumbers and their extracts have gained immense popularity and interest among researchers and nutritionists due to their nutritive value, potential health benefits, and use in the treatment of chronic inflammatory diseases. Many areas of the world use sea cucumbers in traditional foods and folk medicine. Though the actual components and their specific functions still remain to be investigated, most sea cucumber extracts are being studied for their anti-inflammatory functions, immunostimulatory properties, and for cancer prevention and treatment. There is large scope for the discovery of additional bioactive, valuable compounds from this natural source. Sea cucumber extracts contain unique components, such as modified triterpene glycosides, sulfated polysaccharides, glycosphingolipids, and esterified phospholipids. Frondanol A5, an isopropyl alcohol/water extract of the enzymatically hydrolyzed epithelia of the edible North Atlantic sea cucumber, Cucumaria frondosa, contains monosulfated triterpenoid glycoside Frondoside A, the disulfated glycoside Frondoside B, the trisulfated glycoside Frondoside C, 12-methyltetradecanoic acid, eicosapentaenoic acid, and fucosylated chondroitin sulfate. We have extensively studied the efficacy of this extract in preventing colon cancer in rodent models. In this review, we discuss the anti-inflammatory, immunostimulatory, and anti-tumor properties of sea cucumber extracts.

High-value components and bioactives from sea cucumbers for functional foods--a review

Sea cucumbers, belonging to the class Holothuroidea, are marine invertebrates, habitually found in the benthic areas and deep seas across the world. They have high commercial value coupled with increasing global production and trade. Sea cucumbers, informally named as bêche-de-mer, or gamat, have long been used for food and folk medicine in the communities of Asia and Middle East. Nutritionally, sea cucumbers have an impressive profile of valuable nutrients such as Vitamin A, Vitamin B1 (thiamine), Vitamin B2 (riboflavin), Vitamin B3 (niacin), and minerals, especially calcium, magnesium, iron and zinc. A number of unique biological and pharmacological activities including anti-angiogenic, anticancer, anticoagulant, anti-hypertension, anti-inflammatory, antimicrobial, antioxidant, antithrombotic, antitumor and wound healing have been ascribed to various species of sea cucumbers. Therapeutic properties and medicinal benefits of sea cucumbers can be linked to the presence of a wide array of bioactives especially triterpene glycosides (saponins), chondroitin sulfates, glycosaminoglycan (GAGs), sulfated polysaccharides, sterols (glycosides and sulfates), phenolics, cerberosides, lectins, peptides, glycoprotein, glycosphingolipids and essential fatty acids. This review is mainly designed to cover the high-value components and bioactives as well as the multiple biological and therapeutic properties of sea cucumbers with regard to exploring their potential uses for functional foods and nutraceuticals.