Identification of Docetaxel as a Potential Drug to Promote HDL Biogenesis

Biomedical Advances in ABCA1 Transporter: From Bench to Bedside

ATP-binding cassette transporter A1 (ABCA1) has been identified as the molecular defect in Tangier disease. It is biochemically characterized by absence of high-density lipoprotein cholesterol (HDL-C) in the circulation, resulting in the accumulation of cholesterol in lymphoid tissues. Accumulation of cholesterol in arteries is an underlying cause of atherosclerosis, and HDL-C levels are inversely associated with the presence of atherosclerotic cardiovascular disease (ASCVD). ABCA1 increases HDL-C levels by driving the generation of new HDL particles in cells, and cellular cholesterol is removed in the process of HDL generation. Therefore, pharmacological strategies that promote the HDL biogenic process by increasing ABCA1 expression and activity have been intensively studied to reduce ASCVD. Many ABCA1-upregulating agents have been developed, and some have shown promising effects in pre-clinical studies, but no clinical trials have met success yet. ABCA1 has long been an attractive drug target, but the failed clinical trials have indicated the difficulty of therapeutic upregulation of ABCA1, as well as driving us to: improve our understanding of the ABCA1 regulatory system; to develop more specific and sophisticated strategies to upregulate ABCA1 expression; and to search for novel druggable targets in the ABCA1-dependent HDL biogenic process. In this review, we discuss the beginning, recent advances, challenges and future directions in ABCA1 research aimed at developing ABCA1-directed therapies for ASCVD.

Hydroxyurea ameliorates atherosclerosis in ApoE-/- mice by potentially modulating Niemann-Pick C1-like 1 protein through the gut microbiota

Rationale: The efficacy and mechanism of hydroxyurea in the treatment of atherosclerosis have rarely been reported. The goal of this study was to investigate the efficacy of hydroxyurea in high-fat diet-fed ApoE^-/- mice against atherosclerosis and examine the possible mechanism underlying treatment outcomes. Methods: ApoE^-/- mice were fed a high-fat diet for 1 month and then administered hydroxyurea by gavage continuously for 2 months. Aortic root hematoxylin-eosin (H&E) staining and oil red O staining were used to verify the efficacy of hydroxyurea; biochemical methods and ELISA were used to detect changes in relevant metabolites in serum. 16S rRNA was used to detect composition changes in the intestinal bacterial community of animals after treatment with hydroxyurea. Metabolomics methods were used to identify fecal metabolites and their changes. Immunohistochemical staining and ELISA were used for the localization and quantification of intestinal NPC1L1. Results: We showed that aortic root HE staining and oil red O staining determined the therapeutic efficacy of hydroxyurea in the treatment of atherosclerosis in high-fat diet-fed ApoE^-/- mice. Serological tests verified the ability of hydroxyurea to lower total serum cholesterol and LDL cholesterol. The gut microbiota was significantly altered after HU treatment and was significantly different from that after antiplatelet and statin therapy. Meanwhile, a metabolomic study revealed that metabolites, including stearic acid, palmitic acid and cholesterol, were significantly enriched in mouse feces. Further histological and ELISAs verified that the protein responsible for intestinal absorption of cholesterol in mice, NPC1L1, was significantly reduced after hydroxyurea treatment. Conclusions: In high-fat diet-fed ApoE^-/- mice, hydroxyurea effectively treated atherosclerosis, lowered serum cholesterol, modulated the gut microbiota at multiple levels and affected cholesterol absorption by reducing NPC1L1 in small intestinal epithelial cells.

High-Density Lipoprotein and Cardiovascular Disease-Where do We Stand?

Decades of research have shown that high-density lipoprotein cholesterol (HDL-C) levels in humans are associated with atherosclerotic cardiovascular disease (ASCVD). This association is strong and coherent across populations and remains after the elimination of covariates. Animal studies show that increasing HDL particles prevent atherosclerosis, and basic work on the biology of HDL supports a strong biological plausibility for a therapeutic target. This enthusiasm is dampened by Mendelian randomization data showing that HDL-C may not be causal in ASCVD. Furthermore, drugs that increase HDL-C have largely failed to prevent or treat ASCVD.

New Strategies to Promote Macrophage Cholesterol Efflux

The capacity of macrophages to dispose of cholesterol deposited in the atherosclerotic plaque depends on their ability to activate cholesterol efflux pathways. To develop athero-protective therapies aimed at promoting macrophage cholesterol efflux, cholesterol metabolism in THP-1 monocyte-derived macrophages has been extensively studied, but the intrinsic sensitivity of monocytes and the lack of a standardized procedure to differentiate THP-1 monocytes into macrophages have made it difficult to utilize THP-1 macrophages in the same or similar degree of differentiation across studies. The variability has resulted in lack of understanding of how the differentiation affects cholesterol metabolism, and here we review and investigate the effects of THP-1 differentiation on cholesterol efflux. The degree of THP-1 differentiation was inversely associated with ATP binding cassette A1 (ABCA1) transporter-mediated cholesterol efflux. The differentiation-associated decrease in ABCA1-mediated cholesterol efflux occurred despite an increase in ABCA1 expression. In contrast, DSC1 expression decreased during the differentiation. DSC1 is a negative regulator of the ABCA1-mediated efflux pathway and a DSC1-targeting agent, docetaxel showed high potency and efficacy in promoting ABCA1-mediated cholesterol efflux in THP-1 macrophages. These data suggest that pharmacological targeting of DSC1 may be more effective than increasing ABCA1 expression in promoting macrophage cholesterol efflux. In summary, the comparison of THP-1 macrophage subtypes in varying degrees of differentiation provided new insights into cholesterol metabolism in macrophages and allowed us to identify a viable target DSC1 for the promotion of cholesterol efflux in differentiated macrophages. Docetaxel and other pharmacological strategies targeting DSC1 may hold significant potential for reducing atherogenic cholesterol deposition.

Predictive value of a reduction in the level of high-density lipoprotein-cholesterol in patients with non-small-cell lung cancer undergoing radical resection and adjuvant chemotherapy: a retrospective observational study

Background

Cancer patients often exhibit chemotherapy-associated changes in serum lipid profiles, however, their prognostic value before and after adjuvant chemotherapy on survival among non-small-cell lung cancer (NSCLC) patients is unknown.

Methods

NSCLC patients undergoing radical resection and subsequent adjuvant chemotherapy from 2013 to 2017 at Sun Yat-sen University Cancer Center were retrospectively reviewed. Fasted serum lipid levels were measured before and after chemotherapy. The optimal lipid cut-off values at baseline and fluctuation were determined using X-tile™. The fluctuations in serum lipid levels and disease-free survival (DFS) were assessed.

Results

Serum cholesterol, low-density lipoprotein cholesterol (LDL-C), high-density lipoprotein-cholesterol (HDL-C), triglyceride, apolipoprotein (Apo) A-I, and ApoB all significantly increased after adjuvant chemotherapy. X-tile determined 1.52 mmol/L of HDL-C and 0.74 g/L of ApoB as the optimal cut-off values before chemotherapy. Patients with HDL-C ≥ 1.52 mmol/L (median DFS: not reached vs. 26.30 months, P = 0.0005) and a decreased HDL-C level after adjuvant chemotherapy (median DFS: 80.43 vs. 26.12 months, P = 0.0204) had a longer DFS. An HDL-C level that increased by ≥ 0.32 mmol/L after chemotherapy indicated a worse DFS. A high baseline ApoB level were associated with a superior DFS. In the univariate analysis and the multivariate Cox analyses, a high baseline HDL-C level and a HDL-C reduction after adjuvant chemotherapy were independent indicators for superior DFS. High baseline HDL-C was related to N0-1 stage (χ² = 6.413, P = 0.011), and HDL-C fluctuation was significantly correlated with specific chemotherapy regimens (χ² = 5.002, P = 0.025).

Conclusions

Adjuvant chemotherapy increased various lipid levels in resected NSCLC patients. A higher HDL-C level before chemotherapy and a reduced HDL-C level after adjuvant chemotherapy were independent predictors of longer DFS in patients with curable NSCLC.