Arenobufagin is a novel isoform-specific probe for sensing human sulfotransferase 2A1

Abstract

Human cytosolic sulfotransferase 2A1 (SULT2A1) is an important phase II metabolic enzyme. The detection of SULT2A1 is helpful for the functional characterization of SULT2A1 and diagnosis of its related diseases. However, due to the overlapping substrate specificity among members of the sulfotransferase family, it is difficult to develop a probe substrate for selective detection of SULT2A1. In the present study, through characterization of the sulfation of series of bufadienolides, arenobufagin (AB) was proved as a potential probe substrate for SULT2A1 with high sensitivity and specificity. Subsequently, the sulfation of AB was characterized by experimental and molecular docking studies. The sulfate-conjugated metabolite was identified as AB-3-sulfate. The sulfation of AB displayed a high selectivity for SULT2A1 which was confirmed by in vitro reaction phenotyping assays. The sulfation of AB by human liver cytosols and recombinant SULT2A1 both obeyed Michaelis-Menten kinetics, with similar kinetic parameters. Molecular docking was performed to understand the interaction between AB and SULT2A1, in which the lack of interaction with Met-137 and Tyr-238 of SULT2A1 made it possible to eliminate substrate inhibition of AB sulfation. Finally, the probe was successfully used to determine the activity of SULT2A1 and its isoenzymes in tissue preparations of human and laboratory animals.

The Role of Chirality of [18F]SMBT-1 in Imaging of Monoamine Oxidase-B

“…It is important to identify SULT isoforms as enzymes responsible for sulfation of [ 18 F]­SMBT-1 because certain drugs may affect their pharmacokinetics during PET scans. Therefore, we screened SULT isoforms that could efficiently catalyze the sulfation of ( S )- 6 using reported selective SULT inhibitors such as mefenamic acid (SULT1A1), nimesulide (SULT1A1), estrone (SULT1E1), and dehydroepiandrosterone (SULT2A1) . Selective SULT1A1 inhibitors enforced a robust blockade on the production of O -sulfated ( S )- 6 in mouse liver fractions and human liver cytosol fractions; however, selective SULT1E1 and SULT2A1 inhibitors at a concentration of 50 μM (Figure A) did not demonstrate such an activity.…”

“…Therefore, we screened SULT isoforms that could efficiently catalyze the sulfation of (S)-6 using reported selective SULT inhibitors such as mefenamic acid (SULT1A1), nimesulide (SULT1A1), estrone (SULT1E1), and dehydroepiandrosterone (SULT2A1). 27 Selective SULT1A1 inhibitors enforced a robust blockade on the production of O-sulfated (S)-6 in mouse liver fractions and human liver cytosol fractions; however, selective SULT1E1 and SULT2A1 inhibitors at a concentration of 50 μM (Figure 5A) did not demonstrate such an activity. Mefenamic acid markedly and specifically inhibits SULT1A1 activity among NSAIDs.…”

Steroid Sulfation in Adrenal Tumors

“…Specific substrates for the estrogen sulfotransferase SULT1E1 have been described since (121) and most recently been used to image SULT1E1 activity in the brains of human volunteers (122). Other probes target different sulfotransferase isoforms specifically, such as SULT2A1 (123). These new approaches may result in unprecedented imaging opportunities of sulfotransferase activity, when applied to cellular and/or animal models.…”

Gamabufotalin Induces Apoptosis and Cytoprotective Autophagy through the mTOR Signaling Pathway in Hepatocellular Carcinoma

“…Traditional Chinese medicines (TCMs) have gained attention due to their immense potential for inhibiting the growth of a variety of cancers with low toxicity and few side effects. , Toad venom, known as “Chan Su” in TCM, is derived from the skin of the postauricular gland and gargarizan cantor of toads and has been extensively used for centuries as an antineoplastic agent, either by itself or in conjunction with other herbal ingredients. − Gamabufotalin (CS-6), one of the major ingredients in Chan Su, is shown to have high metabolic stability and few adverse effects and therefore is proposed to be used for cancer treatment. − A recent study has shown that Chan Su and its active ingredients have remarkable antitumor activity by inhibiting cellular proliferation and inducing cellular apoptosis and differentiation. , Previous reports demonstrated the efficacy of CS-6 in the treatment of lung cancer, glioblastoma cells, and multiple myeloma cells, etc. ,− However, the efficacy of CS-6 in treating HCC has not been reported in detail.…”