Background: Metabolic reprogramming and epigenetic alterations contribute to the aggressiveness of pancreatic ductal adenocarcinoma (PDAC). Lactate-dependent histone modification is a new type of histone mark, which links glycolysis metabolite to the epigenetic process of lactylation. However, the role of histone lactylation in PDAC remains unclear. Methods: The level of histone lactylation in PDAC was identified by western blot and immunohistochemistry, and its relationship with the overall survival was evaluated using a Kaplan-Meier survival plot. The participation of histone lactylation in the growth and progression of PDAC was confirmed through inhibition of histone lactylation by glycolysis inhibitors or lactate dehydrogenase A (LDHA) knockdown both in vitro and in vivo. The potential writers and erasers of histone lactylation in PDAC were identified by western blot and functional experiments. The potential target genes of H3K18 lactylation (H3K18la) were screened by CUT&Tag and RNA-seq analyses. The candidate target genes TTK protein kinase (TTK) and BUB1 mitotic checkpoint serine/threonine kinase B (BUB1B) were validated through ChIP-qPCR, RT-qPCR and western blot analyses. Next, the effects of these two genes in PDAC were confirmed by knockdown or overexpression. The interaction between TTK and LDHA was identified by Co-IP assay. Results: Histone lactylation, especially H3K18la level was elevated in PDAC, and the high level of H3K18la was associated with poor prognosis. The suppression of glycolytic activity by different kinds of inhibitors or LDHA knockdown contributed to the anti-tumor effects of PDAC in vitro and in vivo. E1A binding protein p300 (P300) and histone deacetylase 2 were the potential writer and eraser of histone lactylation in PDAC cells, respectively. H3K18la was enriched at the promoters and activated the transcription of mitotic checkpoint regulators TTK and BUB1B. Interestingly, TTK and BUB1B could elevate the expression of P300 which in turn increased glycolysis. Moreover, TTK phosphorylated LDHA at tyrosine 239 (Y239) and activated LDHA, and subsequently upregulated lactate and H3K18la levels. Conclusions: The glycolysis-H3K18la-TTK/BUB1B positive feedback loop exacerbates dysfunction in PDAC. These findings delivered a new exploration and significant inter-relationship between lactate metabolic reprogramming and epigenetic regulation, which might pave the way toward novel lactylation treatment strategies in PDAC therapy.

Importance Presence of thyroid autoantibodies in women with normal thyroid function is associated with increased risk of miscarriage. Whether levothyroxine treatment improves pregnancy outcomes among women undergoing in vitro fertilization and embryo transfer (IVF-ET) is unknown. Objective To determine the effect of levothyroxine on miscarriage among women undergoing IVF-ET who had normal thyroid function and tested positive for thyroid autoantibodies. Design, Setting, and Participants An open-label, randomized clinical trial involving 600 women who tested positive for the antithyroperoxidase antibody and were being treated for infertility at Peking University Third Hospital from September 2012 to March 2017. Interventions The intervention group (n = 300) received either a 25-μg/d or 50-μg/d dose of levothyroxine at study initiation that was titrated according to the level of thyroid-stimulating hormone during pregnancy. The women in the control group (n = 300) did not receive levothyroxine. All participants received the same IVF-ET and follow-up protocols. Main Outcomes and Measures The primary outcome was the miscarriage rate (pregnancy loss before 28 weeks of gestation, which was calculated among women who became pregnant). The secondary outcomes were clinical intrauterine pregnancy rate (fetal cardiac activity seen at sonography observation on the 30th day after the embryo transfer), and live-birth rate (at least 1 live birth after 28 weeks of gestation). Results Among the 600 women (mean [SD] age, 31.6 [3.8] years) randomized in this trial, 567 women (94.5%) underwent IVF-ET and 565 (94.2%) completed the study. Miscarriage rates were 10.3% (11 of 107) in the intervention group and 10.6% (12 of 113) in the control group, with the absolute rate difference (RD) of −0.34% (95% CI, −8.65% to 8.12%) over the 4.5-year study period. Clinical intrauterine pregnancy rates were 35.7% (107 of 300) in the intervention group and 37.7% (113 of 300) in the control group, with an absolute RD of −2.00% (95% CI, −9.65% to 5.69%). Live-birth rates were 31.7% (95 of 300) in the intervention group and 32.3% (97 of 300) in the control group, with an absolute RD of −0.67% (95% CI, −8.09% to 6.77%). Conclusions and Relevance Among women in China who had intact thyroid function and tested positive for antithyroperoxidase antibodies and were undergoing IVF-ET, treatment with levothyroxine, compared with no levothyroxine treatment, did not reduce miscarriage rates or increase live-birth rates. Trial Registration Chinese Clinical Trial Registry:ChiCTR-TRC-13004097

Glucagon-like peptide-1 (GLP-1) may have direct favorable effects on cardiovascular system. The aim of this study was to investigate the effects of the GLP-1 analog exenatide on improving coronary endothelial function in patients with type 2 diabetes and to investigate the underlying mechanisms. The newly diagnosed type 2 diabetic subjects were enrolled and given either lifestyle intervention or lifestyle intervention plus exenatide treatment. After 12-wk treatment, coronary flow velocity reserve (CFVR), an important indicator of coronary endothelial function, was improved significantly, and serum levels of soluble intercellular adhesion molecule-1 (sICAM-1) and soluble vascular cell adhesion molecule-1 (sVCAM-1) were remarkably decreased in the exenatide treatment group compared with the baseline and the control group. Notably, CFVR was correlated inversely with hemoglobin A_1c (Hb A_1c) and positively with high-density lipoprotein cholesterol (HDL-C). In human umbilical vein endothelial cells, exendin-4 (a form of exenatide) significantly increased NO production, endothelial NO synthase (eNOS) phosphorylation, and GTP cyclohydrolase 1 (GTPCH1) level in a dose-dependent manner. The GLP-1 receptor (GLP-1R) antagonist exendin (9–39) or GLP-1R siRNA, adenylyl cyclase inhibitor SQ-22536, AMPK inhibitor compound C, and PI3K inhibitor LY-294002 abolished the effects of exendin-4. Furthermore, exendin-4 reversed homocysteine-induced endothelial dysfunction by decreasing sICAM-1 and reactive oxygen species (ROS) levels and upregulating NO production and eNOS phosphorylation. Likewise, exendin (9–39) diminished the protective effects of exendin-4 on the homocysteine-induced endothelial dysfunction. In conclusion, exenatide significantly improves coronary endothelial function in patients with newly diagnosed type 2 diabetes. The effect may be mediated through activation of AMPK/PI3K-Akt/eNOS pathway via a GLP-1R/cAMP-dependent mechanism.

Glucagon-like peptide-1 (GLP-1) and its based agents improve glycemic control. Although their attenuating effect on hepatic glucose output has drawn our attention for decades, the potential mechanisms remain unclear. Cytokine array kit was used to assess cytokine profiles in db/db mice and mouse primary hepatocytes treated with exenatide (exendin-4). Two diabetic mouse models (db/db and Pax6m/+) were treated with a GLP-1 analog exenatide or liraglutide. The expression and secretion of fibroblast growth factor 21 (FGF21) in the livers of diabetic mice, primary mouse and human hepatocytes, and the human hepatic cell line HepG2 treated with or without GLP-1 analog were measured. Blockage of FGF21 with neutralizing antibody or siRNA, or hepatocytes isolated from Fgf21 knockout mice were used, and the expression and activity of key enzymes in gluconeogenesis were analyzed. Serum FGF21 level was evaluated in patients with type 2 diabetes (T2D) receiving exenatide treatment. Utilizing the cytokine array, we identified that FGF21 secretion was upregulated by exenatide (exendin-4). Similarly, FGF21 production in hepatocytes was stimulated by exenatide or liraglutide. FGF21 blockage attenuated the inhibitory effects of the GLP-1 analogs on hepatic glucose output. Similar results were also observed in primary hepatocytes from Fgf21 knockout mice. Furthermore, exenatide treatment increased serum FGF21 level in patients with T2D, particularly in those with better glucose control. We identify that function of GLP-1 in inhibiting hepatic glucose output is mediated via the liver hormone FGF21. Thus, we provide a new extra-pancreatic mechanism by which GLP-1 regulates glucose homeostasis. FUND: National Key Research and Development Program of China, the National Natural Science Foundation of China, the Natural Science Foundation of Beijing and Peking University Medicine Seed Fund for Interdisciplinary Research.