The ATP-binding cassette (ABC) transporter ABCG2 is a significant urate transporter with a high capacity, and it plays a crucial role in the development of hyperuricemia and gout. Therefore, it has the potential to be targeted for therapeutic interventions. Cortex Fraxini, a traditional Chinese medicine (TCM), has been found to possess anti-hyperuricemia properties. However, the specific constituents of Cortex Fraxini responsible for this effect are still unknown, particularly the compound that is responsible for reducing uric acid levels in vivo. In this study, we propose a target screening protocol utilizing bio-affinity ultrafiltration mass spectrometry (BA-UF-MS) to expediently ascertain ABCG2 ligands from the plasma of rats administered with Cortex Fraxini. Our screening protocol successfully identified fraxin as a potential ligand that interacts with ABCG2 when it functions as the targeted protein. Subsequent investigations substantiated fraxin as an activator of ABCG2. These findings imply that fraxin exhibits promise as a drug candidate for the treatment of hyperuricemia. Furthermore, the utilization of BA-UF-MS demonstrates its efficacy as a valuable methodology for identifying hit compounds that exhibit binding affinity towards ABCG2 within TCMs.

The human ABCG2 multidrug transporter plays a crucial role in the absorption and excretion of xeno- and endobiotics, contributes to cancer drug resistance and the development of gout. In this work we have analyzed the effects of selected variants, residing in a structurally unresolved cytoplasmic region (a.a. 354-367) of ABCG2, on the function and trafficking of this protein. A cluster of four lysines (K357-360) and the phosphorylation of a threonine (T362) residue in this region have been previously suggested to significantly affect the cellular fate of ABCG2. Here we report that the naturally occurring K360del variant in human cells increased ABCG2 plasma membrane expression and accelerated cellular trafficking. The variable alanine replacements of the neighboring lysines had no significant effect on transport function, and the apical localization of ABCG2 in polarized cells has not been altered by any of these mutations. Moreover, in contrast to previous reports, we found that the phosphorylation incompetent T362A, or the phosphorylation mimicking T362E variants in this loop, had no measurable effects on the function or expression of ABCG2. Molecular dynamics simulations indicated an increased mobility of the mutant variants with no major effects on the core structure of the protein. These results may help to decipher the potential role of this unstructured region within this transporter.

Fagonia indica is a perennial plant grown in arid climates and utilised in traditional medicine as a treatment for cancer. Previous research has highlighted potential antineoplastic effects of Fagonia indica against breast cancer cell lines. Despite this, there has been little research demonstrating the potential of an aqueous extract of Fagonia indica against colon cancer. Colon cancer is a leading cause of cancer-related mortality, with drug resistance remaining a barrier to treatment. The aim of the present study was to investigate the cytotoxic mechanisms of Fagonia indica in colon cancer cells, including pathways related to proliferation, angiogenesis and inflammation, and ABC membrane transporters. Treatment with Fagonia indica caused a reduction in cell viability in wild-type and chemotherapy resistant colon cancer. Results indicated a role for Akt/ MAPK signalling as a mechanism of Fagonia indica induced cell death, alongside a reduction in the expression of VEG-F, NK-κB and ICAM-1. RT-PCR demonstrated a reduction in expression of ABCG2/ABCC4 in resistant colon cancers, after treatment with Fagonia indica extract. Further research is required to isolate bioactive compounds of Fagonia indica for use against colon cancer.

Gout is at least 3 times more prevalent in men than in women. However, concurrent with rising total gout prevalence, complex factors, including comorbidities, diet and lifestyle, and aging, have promoted higher gout prevalence in females. This narrative review focuses on summarizing recent developments in the landscape of gout in women, and mechanisms involved. New knowledge on sex hormone effects on both urate-excreting and urate-reabsorbing transporters, and higher hypertension and chronic kidney disease prevalence in women compared to men, may help explain why gout incidence rises robustly after menopause in women to approach that in men. Racial and ethnic factors, risk profiles based on heritable genetic polymorphisms of urate transporters, and diet, body mass index, and lifestyle factors differ according to sex. In addition, sex differences in clinical phenotypes and outcomes of gout and non-gout illnesses include more frequent comorbidities, more pain and disability during gout flare, different perceptions of disease burden, and more frequent severe cutaneous hypersensitivity reaction to allopurinol in women. Significantly, women with gout also have poorer COVID-19 outcomes than do men. Collectively, such findings support the potential clinical benefits of tailoring gout and hyperuricemia treatment according to sex.