bims-supasi Biomed News
on Sulfation pathways and signalling
Issue of 2022‒02‒06
five papers selected by
Jonathan Wolf Mueller
University of Birmingham

  1. Front Pharmacol. 2021 ;12 802539
      Glucuronidation and sulfation are the most typical phase II metabolic reactions of drugs. The resulting glucuronide and sulfate conjugates are generally considered inactive and safe. They may, however, be the most prominent drug-related material in the circulation and excreta of humans. The glucuronide and sulfate metabolites of drugs typically have limited cell membrane permeability and subsequently, their distribution and excretion from the human body requires transport proteins. Uptake transporters, such as organic anion transporters (OATs and OATPs), mediate the uptake of conjugates into the liver and kidney, while efflux transporters, such as multidrug resistance proteins (MRPs) and breast cancer resistance protein (BCRP), mediate expulsion of conjugates into bile, urine and the intestinal lumen. Understanding the active transport of conjugated drug metabolites is important for predicting the fate of a drug in the body and its safety and efficacy. The aim of this review is to compile the understanding of transporter-mediated disposition of phase II conjugates. We review the literature on hepatic, intestinal and renal uptake transporters participating in the transport of glucuronide and sulfate metabolites of drugs, other xenobiotics and endobiotics. In addition, we provide an update on the involvement of efflux transporters in the disposition of glucuronide and sulfate metabolites. Finally, we discuss the interplay between uptake and efflux transport in the intestine, liver and kidneys as well as the role of transporters in glucuronide and sulfate conjugate toxicity, drug interactions, pharmacogenetics and species differences.
    Keywords:  ABC transporter; UDP-glucuronosyltransferase (UGT); acyl glucuronide; drug-drug interaction (DDI); enterohepatic recycling; solute carrier; sulfotransferase (SULT); transporter inhibition
  2. Sci Rep. 2022 Jan 31. 12(1): 1625
      Sulfotransferase 4A1 (SULT4A1) is an orphan member of the cytosolic SULT superfamily that contains enzymes that catalyze the sulfonation of hydrophobic drugs and hormones. SULT4A1 has been assessed through all classical SULT approaches yet no SULT activity has been reported. To ascertain SULT4A1 function and activity, we utilized Saccharomyces cerevisiae as a model system, which exhibits no endogenous SULT activity nor possesses SULT-related genes. We observed that ectopic SULT4A1 expression in yeast displays similar subcellular localization as reported in mouse neurons and observed that SULT4A1 is associated with the outer mitochondria membrane. SULT4A1 expression stimulates colony formation and protects these cells from hydrogen peroxide and metabolism-associated oxidative stress. These SULT4A1-mediated phenotypes are dependent on extracellular sulfate that is converted in yeast to PAPS, the universal sulfonate donor for SULT activity. Thus, heterologous SULT4A1 expression in yeast is correctly distributed and functional, and SULT4A1 antioxidant activity is sulfate dependent supporting the concept that SULT4A1 has sulfate-associated activity.
  3. Xenobiotica. 2022 Jan 31. 1-49
      1. LSZ102 is an orally bioavailable selective estrogen receptor degrader in clinical development for the treatment of breast cancer. Preclinical studies showed efficacy in xenograft models on oral dosing. However, oral bioavailability was relatively low in several preclinical species (7-33%), and was associated with first-pass metabolism, particularly intestinal first-pass.2. To investigate metabolism and first-pass effects, metabolites were analysed in human plasma samples after oral dosing of LSZ102 to patients, rat plasma samples after oral dosing of [14C]LSZ102, and in vitro incubations of [14C]LSZ102 with human and rat hepatocytes and intestinal S9 fractions. The kinetics of human sulfotransferase enzymes potentially involved in metabolism of LSZ102 were characterized.3. Sulfate metabolites were found to be the major components in human plasma, as well as in human hepatocytes and intestinal S9 fractions. Contrastingly, glucuronidation was predominant in rat plasma, hepatocytes and intestinal S9. LSZ102 was found to be metabolized by several human sulfotransferases expressed in liver and intestine. The combined metabolism data in rat and human provide supporting evidence for an extensive intestinal first-pass metabolism effect via sulfation in human but glucuronidation in rat.4. As LSZ102 is metabolized by a number of different sulfotransferases, drug-drug interactions resulting from the inhibition of one sulfotransferase are unlikely.5. Despite the observed species difference in metabolism, the major human metabolites of LSZ102, sulfate M5, glucuronide M4, and secondary glucuronide/sulfate metabolite M12, have no or weak pharmacological activity and are not considered a toxicity risk as they are phase II conjugative metabolites.
    Keywords:  LSZ102; SERD; SULT; selective estrogen receptor degrader; sulfotranferase
  4. Environ Sci Pollut Res Int. 2022 Jan 31.
      Steroid arylsulfatase is an important enzyme in human, which plays an important role in dynamic equilibrium of natural estrogens. On the other hand, sulfite can be endogenously produced as a consequence of human body's metabolism of sulfur-containing amino acids, while its main sources to human are mainly derived from food as it is a widely used additive. Sulfite-sensitivity is a well-known phenomenon to a small proportion of populations. However, its potential adverse effects on healthy individuals have been hardly reported. It was for the first time reported in this study that sulfite could effectively inhibit arylsulfatase, and its IC50 values for the snail- and human urine-derived arylsulfatase were determined to be 71.9 and 142.8 µM, which were lower than the concentration of sulfite in some healthy population. Consequently, it appears that sulfite might disrupt estrogen homeostasis in human, and this deserves further investigation.
    Keywords:  Arylsulfatase; Disruption; Estrogen homeostasis; Inhibition; Sulfite
  5. Int Immunol. 2022 Jan 30. pii: dxac002. [Epub ahead of print]
      The effective tumor immunotherapy requires physical contact of T cells with cancer cells. However, tumors often constitute a specialized microenvironment that excludes T cells from the vicinity of cancer cells, and its underlying mechanisms are still poorly understood. DOCK2 is a Rac activator critical for migration and activation of lymphocytes. We herein show that cancer-derived cholesterol sulfate (CS), a lipid product of the sulfotransferase SULT2B1b, acts as a DOCK2 inhibitor and prevents tumor infiltration by effector T cells. Using clinical samples, we found that CS was abundantly produced in certain types of human cancers such as colon cancers. Functionally, CS-producing cancer cells exhibited resistance to cancer-specific T cell transfer and immune checkpoint blockade. Although SULT2B1b is known to sulfate oxysterols and inactivate their tumor-promoting activity, the expression levels of cholesterol hydroxylases, which mediate oxysterol production, are low in SULT2B1b-expressing cancers. Therefore, SULT2B1b inhibition could be a therapeutic strategy to disrupt tumor immune evasion in oxysterol-non-producing cancers. Thus, our findings define a previously unknown mechanism for tumor immune evasion and provide a novel insight into the development of effective immunotherapies.
    Keywords:  DOCK2; SULT2B1b; cholesterol sulfate; immune evasion