Glycyrrhetinic Acid Induces Anoikis-Like Death and Cytoskeletal Disruption in the Central Nervous System Tumorigenic Cells

Abstract

Licorice extracts and the principal licorice component glycyrrhizin (GL) are used worldwide in foods, tobacco and medicines. The sweet taste of licorice roots arises from GL, which is reputed to be at least 50 times sweeter than refined sugar. Owing to this sweetness, GL is extensively used as a natural sweetener and flavoring additive.1) GL is a saponin compound comprising a triterpenoid aglycone, glycyrrhetinic acid (GA), conjugated to a disaccharide of glucuronic acid. GA is used as an antitoxic and immunological regulatory agent for the prevention or treatment of viral infection, inflammation and anaphylaxis.2,3) However, despite its wide use in the market and great effects on some physiological aspects, to the best of our knowledge, no studies have investigated the antitumor effects of GA on tumor cells in the central nervous system (CNS).Serum-free mouse embryo (SFME) cells were originally derived from a 16-d-old whole Balb/c mouse embryo and are maintained in a serum-free culture medium.4) These cells do not undergo growth crisis, maintain their diploid karyotype for extended passages and are non-tumorigenic in vivo. Consequently, they are non-transformed, behave as primary cultures, have a finite lifespan and display the characteristics of CNS progenitor cells.5,6) SFME cells were cotransfected with the human c-Ha-ras and mouse c-myc genes, and the resulting cells were designated ras/myc SFME cells. 7) While SFME cells are non-tumorigenic in vivo, 5,6) ras/myc SFME cells are tumorigenic and do not require any growth factors, such as epidermal growth factor. 7) Another line of SFME-derived tumorigenic cells are highly metastatic ras/myc SFME-1 (r/m HM-SFME-1) cells, which were established by selecting ras/myc SFME cells that only metastasize to the lungs of Balb/c mice. 8) In the present study, r/m HM-SFME-1 cells were treated with GA and its efficacy as an antitumor agent through anoikis-like cell death and cytoskeletal disruption was investigated. Cell Culture SFME and r/m HM-SFME-1 cells were cultured in a humidified 5% CO 2 -95% air atmosphere at 37°C in 60 mm diameter dishes, pre-coated with 10 mg/ml fibronectin. The basal nutrient culture medium was a 1 : 1 mixture of Dulbecco's modified Eagle's medium and Ham's F12 9,10) containing 15 mM N-(2-hydroxyethyl)piperazine-NЈ-2-ethanesulfonic acid (HEPES), pH 7.4, 1.2 mg/ml sodium bicarbonate, 10 nM sodium selenite and 10 mg/ml gentamicin, supplemented with insulin (10 mg/ml), transferrin (25 mg/ml) and epidermal growth factor (50 ng/ml). Cell passages were accomplished by rapid trypsinization with 0.2% crude trypsin and 1 mM ethylenediaminetetraacetate in phosphatebuffered saline (PBS) without calcium or magnesium, followed by dilution in the culture medium at room temperature. The medium containing the collected cells was centrifuged at 250 g at 4°C for 7 min and the supernatant was removed. The cells were suspended in the culture medium without the supplements, plated at 1ϫ10 5 cells/dish and cultured again in the medium with the supplements. Following...

Glycyrrhiza Genus: Enlightening Phytochemical Components for Pharmacological and Health‐Promoting Abilities

“…Rare causes of apparent mineralocorticoid excess include the genetic deficiency of 11- β -HSD2, sometimes present in adulthood, which although usually appears in childhood, it is often asymptomatic and may stay undiagnosed until adulthood [ 229 ]. An in vitro evaluation demonstrated that glycyrrhetinic acid in humans at relevant concentrations may disturb cell adhesion, effect anoikis-like cell death, cause morphologic changes, and disturb cytoskeletal proteins [ 230 ].…”

A Systematic Review of the Anticancer Properties of Compounds Isolated from Licorice (Gancao)

“…The proliferative inhibition of vinblastine in P-glycoprotein-overexpressing human carcinoma KB-C2 and doxorubicin in KB/MDR cells are also enhanced with the combined treatment of GA [87]. Others: GA induces anoikis-like cell death and disturbs cytoskeletal protein expression in central nervous system tumorigenic cells [88]. In NSCLC cells, GA inhibits cell proliferation by inhibiting the activity of the thromboxane synthase protein, which is overexpressed in NSCLC and carries a poor prognosis [89].…”

Ligand-receptor Interaction between Triterpenoids and the 11β-Hydroxysteroid dehydrogenase type 2 (11βHSD2) Enzyme Predicts Their Toxic Effects against Tumorigenic r/m HM-SFME-1 Cells

“…Ras pathways have been targeted for the development of chemotherapeutic interventions against tumor cells by interfering with cytoskeletal proteins such as actin (31) and tubulin (43). Furthermore, in our previous (44,45) and current studies, we found that GA disrupted F-actin and ␤III-tubulin, which could lead to loss of functionality for cell growth or proliferation and result in apoptosis of the cells. These findings indicate that disturbances in cytoskeletal proteins may be the factors involved in the toxic effects of GA against the tumor cells.…”