Shi, S. L. | bioRxiv Science

bioRxiv2024

Taurine/chenodeoxycholic acid ratio as a circulating biomarker of insidious vitamin B12 deficiency in humans

Deficiency of vitamin B12 (B12), an essential water-soluble vitamin, leads to irreversible neurological damage, osteoporosis, cardiovascular diseases, and anemia. Clinical tests to detect B12deficiency lack specificity and sensitivity. B12 deficiency is thus insidious because progressive decline in organ functions may go unnoticed until the damage is advanced or irreversible. Here, using targeted unbiased metabolomic profiling in the sera of B12-deficient versus control individuals, we set out to identify biomarker(s) of B12 deficiency. Metabolomic profiling identified 77 metabolites, and Partial least squares discriminant-analysis (PLS-DA) and hierarchical clustering analysis (HCA) showed a differential abundance in B12-deficient sera of taurine, xanthine, hypoxanthine, chenodeoxycholic acid, neopterin, and glycocholic acid. Random forest (RF) multivariate analysis identified a taurine/chenodeoxycholic acid ratio, with an AUC score of 1, to be the best biomarker to predict B12 deficiency. Mechanistically, B12 deficiency reshaped the transcriptomic and metabolomic landscape of the cell identifying a downregulation of methionine, taurine, urea cycle, and nucleotide metabolism, and an upregulation of Krebs cycle. Thus, we propose taurine/chenodeoxycholic acid ratio in serum as a potential biomarker of B12 deficiency in humans and elucidate cellular metabolic pathways regulated by B12 deficiency.

pharmacology and toxicology↗

bioRxiv2018

Artesunate pErk up HepG2 cells to die through apoptosis in vitro

The dilemma between in vitro and in vivo drug screening results persisted to hinder preclinical anti-cancer drug development. In this study, drug screening was initially performed on monolayer cultures of HepG2 cells, whereas in vivo drug testing was performed on the subcutaneous xenograft mouse model of HepG2 cells in athymic nude mice. Results showed that Artesunate inhibited HepG2 cell growth in vitro, but was ineffective in vivo. Hence, we investigated the difference between in vitro and in vivo settings using this cell-drug combination as a model. Immuno-staining of hepatocellular carcinoma (HCC) biomarkers showed that -fetoprotein (AFP) was unaffected by Artesunate treatment in vitro or in vivo, suggesting that AFP was neither a biomarker nor response indicator. Alternatively, high albumin was detected in both monolayer and organoid cultures; contrariwise, the xenograft tumors prevailed low albumin, in consistency to human HCC with poor prognosis. Artesunate treatment reduced intracellular albumin expression in vitro; Artesunate did not alter tissue and serum albumin in xenograft mice, in coincidence with its irresponsiveness in vivo. However, Artesunate binding to albumin was undetectable. Instead, we observed a transient stimulation of Erk1/2 phosphorylation followed by DAPK1 dephosphorylation and apoptosis. Combined treatment of Artesunate with U0126 revoked Erk1/2-DAPK1 phosphorylation and exerted modest proliferative advantage at early time points, but eventually did not rescue HepG2 cells from death. U0126 induced multiploid formation independent of Artesunate, resulting in cell cycle arrest within 24 h post-treatment.\n\nSignificanceSystematic investigation of HCC biomarkers AFP and albumin among the in vitro models of monolayer and organoid cultures, and the in vivo models of subcutaneous and liver implantation xenograft mice was conducted.

cell biology↗