Although platinum-based chemotherapy is the frontline regimen for colorectal cancer (CRC), drug resistance remains a major challenge affecting its therapeutic efficiency. However, there is limited research on the correlation between chemotherapy resistance and lipid metabolism, including PIK3CA mutant tumors. In this present study, we found that PIK3CA-E545K mutation attenuated cell apoptosis and increased the cell viability of CRC with L-OHP treatment in vitro and in vivo. Mechanistically, PIK3CA-E545K mutation promoted the nuclear accumulation of SREBP1, which promoted the transcription of Apolipoprotein A5 (APOA5). APOA5 activated the PPARγ signaling pathway to alleviate reactive oxygen species (ROS) production following L-OHP treatment, which contributed to cell survival of CRC cells. Moreover, APOA5 overexpression enhanced the stemness-related traits of CRC cells. Increased APOA5 expression was associated with PIK3CA mutation in tumor specimens and poor response to first-line chemotherapy, which was an independent detrimental factor for chemotherapy sensitivity in CRC patients. Taken together, this study indicated that PIK3CA-E545K mutation promoted L-OHP resistance by upregulating APOA5 transcription in CRC, which could be a potent target for improving L-OHP chemotherapeutic efficiency. Our study shed light to improve chemotherapy sensitivity through nutrient management in CRC.

OBJECTIVE: To study the role of gene mutations in the development of severe hypertriglyceridemia (HTG) in patients with hyperlipidemic acute pancreatitis (HLAP), especially different apolipoprotein A5 (APOA5) mutations.
METHODS: Whole-exome sequencing was performed on 163 patients with HLAP and 30 patients with biliary acute pancreatitis (BAP). The pathogenicity of mutations was then assessed by combining clinical information, predictions of bioinformatics programs, information from multiple gene databases, and residue location and conservation. The pathogenic mutations of APOA5 were visualized using the software.
RESULTS: 1. Compared with BAP patients, pathogenic mutations of APOA5 were frequent in HLAP patients; among them, the heterozygous mutation of p.G185C was the most common. 2. All six pathogenic mutations of APOA5 identified in this study (p.S35N, p.D167V, p.G185C, p.K188I, p.R223C, and p.H182fs) were positively correlated with severe HTG; they were all in the important domains of apolipoprotein A-V (apoA-V). Residue 223 is strictly conserved in multiple mammals and is located in the lipoprotein lipase (LPL)-binding domain (Pro215-Phe261). When Arg 223 is mutated to Cys 223, the positive charge of this residue is reduced, which is potentially destructive to the binding function of apoA-V to LPL. 3. Four new APOA5 mutations were identified, namely c.563A > T, c.667C > T, c.788G > A, and c.544_545 insGGTGC.
CONCLUSIONS: The pathogenic mutations of APOA5 were specific to the patients with HLAP and severe HTG in China, and identifying such mutations had clinical significance in elucidating the etiology and subsequent treatment.

Background: Apolipoprotein A5 (APOA5) is involved in serum triglyceride (TG) regulation. Several studies have reported that the rs651821 locus in the APOA5 gene is associated with serum TG levels in the Chinese population. However, no research has been performed regarding the association between the variants of rs651821 and the risk of hyperlipidemic acute pancreatitis (HLAP). Methods: A case-control study was conducted and is reported following the STROBE guidelines. We enrolled a total of 88 participants in this study (60 HLAP patients and 28 controls). APOA5 was genotyped using PCR and Sanger sequencing. Logistic regression models were conducted to calculate odds ratios and a 95% confidence interval. Results: The genotype distribution of the rs651821 alleles in both groups follow the Hardy-Weinberg distribution. The frequency of the \"C\" allele in rs651821 was increased in HLAP patients compared to controls. In the recessive model, subjects with the \"CC\" genotype had an 8.217-fold higher risk for HLAP (OR = 8.217, 95% CI: 1.023-66.01, p = 0.046) than subjects with the \"TC+TT\" genotypes. After adjusting for sex, the association remained significant (OR = 9.898, 95% CI: 1.176-83.344, p = 0.035). Additionally, the \"CC\" genotype was related to an increased TG/apolipoprotein B (APOB) ratio and fasting plasma glucose (FPG) levels. Conclusions: Our findings suggest that the C allele of rs651821 in APOA5 increases the risk of HLAP in persons from Southeastern China.

Salusin‑α and adiponectin, are vasoactive peptides with numerous similar biological effects related to lipid metabolism. Adiponectin has been shown to reduce fatty acid oxidation and to inhibit lipid synthesis of liver cells through its receptor, adiponectin receptor 2 (AdipoR2), but whether salusin‑α is able to interact with AdipoR2, was not previously reported. To investigate this, in vitro experiments were carried out. The overexpression and interference recombinant plasmids were constructed with salusin‑α. The lentiviral expression systems of salusin‑α overexpression and interference were respectively synthesized in 293T cells, and 293T cells were infected with the lentivirus. Finally, the association between salusin‑α and AdipoR2 was analyzed by semi‑quantitative PCR. Subsequently, HepG2 cells were also infected with these viruses. The expression levels of AdipoR2, peroxisome proliferator‑activated receptor‑α (PPARα), apolipoprotein A5 (ApoA5) and sterol regulatory element‑binding transcription factor 1 (SREBP‑1c) were detected by western blotting, and AdipoR2 inhibitor (thapsigargin) and agonist [4‑phenyl butyric acid (PBA)] were used to observe the resultant changes in the aforementioned molecules. The results obtained revealed that the overexpression of salusin‑α increased the level of AdipoR2 in 293T and HepG2 cells, led to an upregulation of the levels of PPARα and ApoA5, and inhibited the expression of SREBP‑1c, whereas the salusin‑α interference lentivirus exerted the opposite effects. Notably, thapsigargin inhibited the expression of AdipoR2, PPARα and ApoA5 in HepG2 cells of pHAGE‑Salusin‑α group, and caused an increase in the level of SREBP‑1c, whereas the opposite effects were observed in pLKO.1‑shSalusin‑α#1 group upon treatment with PBA. Taken together, these data demonstrated that overexpression of salusin‑α upregulated AdipoR2, which in turn activated the PPARα/ApoA5/SREBP‑1c signaling pathway to inhibit lipid synthesis in HepG2 cells, thereby providing theoretical data on which to base the clinical application of salusin‑α as a novel peptide for molecular intervention in fatty liver disease.

Genetic variations in APOC2 and APOA5 genes involve activating lipoprotein lipase (LPL), responsible for the hydrolysis of triglycerides (TG) in blood and whose impaired functions affect the TG metabolism and are associated with metabolic diseases. In this study, we investigate the biological significance of genetic variations at the DNA sequence and structural level using various computational tools. Subsequently, 8 (APOC2) and 17 (APOA5) non-synonymous SNPs (nsSNPs) were identified as high-confidence deleterious SNPs based on the effects of the mutations on protein conservation, stability, and solvent accessibility. Furthermore, based on our docking results, the interaction of native and mutant forms of the corresponding proteins with LPL depicts differences in root mean square deviation (RMSD), and binding affinities suggest that these mutations may affect their function. Furthermore, in vivo, and in vitro studies have shown that differential expression of these genes in disease conditions due to the influence of nsSNPs abundance may be associated with promoting the development of cancer and cardiovascular diseases. Preliminary screening using computational methods can be a helpful start in understanding the effects of mutations in APOC2 and APOA5 on lipid metabolism; however, further wet-lab experiments would further strengthen the conclusions drawn from the computational study.

BACKGROUND: Pulmonary arterial hypertension (PAH) is a chronic, progressive lung vascular disease accompanied by elevated pulmonary vascular pressure and resistance, and it is characterized by increased pulmonary artery smooth muscle cell (PASMC) proliferation. Apolipoprotein A5 (ApoA5) improves monocrotaline (MCT)-induced PAH and right heart failure; however, the underlying mechanism remains unknown. Here we speculate that ApoA5 has a protective effect in pulmonary vessels and aim to evaluate the mechanism.
METHODS: ApoA5 is overexpressed in an MCT-induced PAH animal model and platelet-derived growth factor (PDGF)-BB-induced proliferating PASMCs. Lung vasculature remodeling was measured by immunostaining, and PASMC proliferation was determined by cell counting kit-8 and 5-ethynyl-2\'-deoxyuridine5-ethynyl-2\'-deoxyuridine incorporation assays. Coimmunoprecipitation-mass spectrometry was used to investigate the probable mechanism. Next, its role and mechanism were further verified by knockdown studies.
RESULTS: ApoA5 level was decreased in MCT-induced PAH lung as well as PASMCs. Overexpression of ApoA5 could help to inhibit the remodeling of pulmonary artery smooth muscle. ApoA5 could inhibit PDGF-BB-induced PASMC proliferation and endoplasmic reticulum stress by increasing the expression of glucose-regulated protein 78 (GRP78). After knocking down GRP78, the protecting effects of ApoA5 have been blocked.
CONCLUSIONS: ApoA5 ameliorates MCT-induced PAH by inhibiting endoplasmic reticulum stress in a GRP78 dependent mechanism.

Nonalcoholic fatty liver disease (NAFLD) is a common chronic disease characterized by the excessive accumulation of hepatocyte fat and steatosis in the absence of alcohol or any other clear contributing factors to liver injury. NAFLD has been confirmed to be closely associated with obesity, insulin resistance, and dyslipidemia. Genetic polymorphism studies have shown the relations between the apolipoprotein A5 gene (APOA5) and NAFLD. However, the association between the serum ApoA5 level and NAFLD remains unclear. Between September 2018 and August 2019, adults who attended the hospital-based health checkup center were enrolled in this study. Anthropometric examination, laboratory investigations on fasting blood, and abdominal ultrasonography were performed. The serum ApoA5 level was determined by enzyme-linked immunosorbent assay. A total of 517 eligible participants (317 females and 200 males) were involved in this study, with a mean age of 54.7 ± 16.7 years. The mean ApoA5 concentration was 28.8 ± 4.7 μg/ml, among which the males had higher concentration levels than females (29.3 ± 4.5 vs. 28.5 ± 4.7 μg/mL, P=0.04). Serum ApoA5 level was not significantly correlated with NAFLD or metabolic profiles. However, the prevalence rate of hypertriglyceridemia (triglyceride ≥ 1.7 mmol/L) showed a significant inverted \"U\"-shaped trend in individuals with the serum ApoA5 level of quartile one to quartile four after adjusting the confounding factors. Moreover, individuals with higher serum ApoA5 levels were also more likely to suffer from hyperglycemia. The ApoA5 levels and the prevalence of hypertriglyceridemia are in an inverted \"U-shaped\" correlation, but there is no significant difference between ApoA5 levels, NAFLD, and metabolic syndrome.

OBJECTIVE: Long-term treatment of olanzapine, the most widely-prescribed second-generation antipsychotic, remarkably increases the risk of non-alcoholic fatty liver disease (NAFLD), whereas the mechanism for olanzapine-induced NAFLD remains unknown. Excessive hepatic fat accumulation is the basis for the pathogenesis of NAFLD, which results from the disturbance of TG metabolism in the liver. Apolipoprotein A5 (ApoA5) is a key regulator for TG metabolism in vivo that promotes TG accumulation in hepatocytes, thereby resulting in the development of NAFLD. However, there are no data indicating the role of apoA5 in olanzapine-induced NAFLD. Therefore, this study aims to investigate the role of apoA5 in olanzapine-induced NAFLD.
METHODS: This study was carried out via animal studies, cell experiment, and ApoA5 gene knockdown experiment. Six-week-old male C57BL/6J mice were randomized into a control group, a low-dose group, and a high-dose group, which were treated by 10% DMSO, 3 mg/(kg·d) olanzapine, and 6 mg/(kg·d) olanzapine, respectively for 8 weeks. The lipid levels in plasma, liver function indexes, and expression levels of ApoA5 were detected. HepG2 cells were treated with 0.1% DMSO (control group), 25 μmol/L olanzapine (low-dose group), 50 μmol/L olanzapine (medium-dose group), and 100 μmol/L olanzapine (high-dose group) for 24 h. HepG2 cells pretreated with 100 μmol/L olanzapine were transfected with siRNA and scrambled siRNA (negative control), respectively. We observed the changes in lipid droplets within liver tissues and cells using oil red O staining and fat deposition in liver tissues using HE staining. The mRNA and protein levels of ApoA5 were determined by real-time PCR and Western blotting, respectively.
RESULTS: After intervention with 3 and 6 mg/(kg·d) olanzapine for 8 weeks, there was no significant difference in body weight among the 3 groups (P>0.05). Olanzapine dose-dependently increased the plasma TG, ALT and AST levels, and reduced plasma ApoA5 levels (all P<0.05), whereas there was no significant difference in plasma cholesterol (HDL-C, LDL-C, and TC) levels among the 3 groups (all P>0.05). Olanzapine dose-dependently up-regulated ApoA5 protein levels in liver tissues (all P<0.05), but there was no significant change in ApoA5 mRNA expression among groups (P>0.05). In the control group, the structure of liver tissues was intact, the morphology of liver cells was regular, and only a few scattered lipid droplets were found in the cells. In the olanzapine-treated group, there was a large amount of lipid deposition in hepatocytes, and cells were balloon-like and filled with lipid droplet vacuoles. The nucleus located at the edge of cell, and the number of lipid droplets was increased significantly, especially in the high-dose group. Likewise, when HepG2 cells were treated with olanzapine for 24 h, the number and size of lipid droplets were significantly elevated in a dose-dependent manner. Moreover, olanzapine dose-dependently up-regulated ApoA5 protein levels in HepG2 cells (all P<0.05), but there was no significant difference in ApoA5 mRNA expression among groups (P>0.05). Compared with the HepG2 cells transfected with scrambled siRNA, the number and size of lipid droplets in HepG2 cells transfected with ApoA5 siRNA were significantly reduced.
CONCLUSIONS: The short-term intervention of olanzapine does not significantly increase body weight of mice, but it can directly induce hypertriglyceridemia and NAFLD in mice. Olanzapine inhibits hepatic apoA5 secretion but does not affect hepatic apoA5 synthesis, resulting in the pathogenesis of NAFLD. Inhibition of apoA5 secretion plays a key role in the development of olanzapine-related NAFLD, which may serve as an intervention target for this disease.
目的: 奥氮平是最常用第2代抗精神病药，若长期服用会显著增加发生非酒精性脂肪性肝病(non-alcoholic fatty liver disease，NAFLD)的风险，但其发病机制不明。肝内脂肪过度沉积是NAFLD的病理基础，且与肝内TG代谢障碍密切相关。载脂蛋白A5(apolipoprotein A5，ApoA5)是体内TG代谢的关键调节因子，促进肝细胞内TG蓄积，参与NAFLD发病。然而，奥氮平是否通过ApoA5诱发NAFLD尚无报道。本研究探讨ApoA5是否参与奥氮平相关NAFLD的发病。方法: 从动物实验、细胞实验及ApoA5基因敲低实验3个层次上进行探讨。将6周龄雄性C57BL/6J小鼠随机分为对照组、低剂量组、高剂量组，分别给予10% DMSO、3 mg/(kg·d)奥氮平、6 mg/(kg·d)奥氮平。干预8周后，测定各组小鼠的血脂4项、肝转氨酶2项和ApoA5水平。HepG2细胞分为对照组、低剂量组、中剂量组、高剂量组，分别给予0.1% DMSO、25 μmol/L奥氮平、50 μmol/L奥氮平、100 μmol/L奥氮平干预24 h。对100 μmol/L奥氮平预处理的HepG2细胞分别转染ApoA5 siRNA或scrambled siRNA(阴性对照)。采用油红O染色观察肝组织和肝细胞中的脂滴；HE染色观察肝组织脂质沉积情况；实时PCR检测ApoA5 mRNA表达水平；蛋白质印迹法检测ApoA5蛋白质表达水平。结果: 3或6 mg/(kg·d)的奥氮平干预后，各组小鼠体重差异无统计学意义(P>0.05)，血浆TG、ALT和AST水平呈剂量依赖性升高，血浆ApoA5水平呈剂量依赖性降低(均P<0.05)；但各组小鼠血浆胆固醇(HDL-C、LDL-C、TC)水平差异均无统计学意义(均P>0.05)。肝组织中ApoA5蛋白质水平呈剂量依赖性升高(均P<0.05)，但各组ApoA5 mRNA表达差异无统计学意义(P>0.05)。对照组小鼠肝组织结构完整，肝细胞形态规则，细胞内仅见少量散在脂滴；给予3或6 mg/(kg·d)奥氮平的小鼠肝细胞内可见大量脂肪沉积，细胞呈气球样变，充盈着大量的脂滴空泡，细胞核位于细胞边缘，红色脂滴数量明显增多，且高剂量组更明显。25、50、100 μmol/L的奥氮平干预HepG2细胞24 h后，细胞内脂滴数量明显增多和体积明显增大，且给药剂量越高变化越明显；细胞中ApoA5蛋白质水平呈剂量依赖性升高(P<0.05)，但各组ApoA5 mRNA表达差异无统计学意义(P>0.05)。与转染scrambled siRNA的HepG2细胞相比，转染ApoA5 siRNA的HepG2细胞内脂滴的数量明显减少，体积明显缩小。结论: 奥氮平短期干预，虽不显著增加小鼠体重，但可直接诱发高TG血症和NAFLD；奥氮平通过抑制肝脏ApoA5分泌(但不影响肝脏ApoA5合成)，诱导NAFLD发病，提示ApoA5分泌障碍是奥氮平相关NAFLD发病的关键机制及干预靶点。.

The Apolipoprotein A5 (APOA5) rs662799 was significantly associated with blood lipid level at genome-wide significance level. Whether dynamic changes of adiposity influence the effect of lipid loci on long-term blood lipid profile remains unclear. We assessed interactions of 5-year body mass index (BMI) change and rs662799 genotypes with risk of incident dyslipidemia and longitudinal changes in serum lipids in a prospective cohort.
We included 4329 non-dyslipidemia participants aged ≥ 40 years at baseline from a well-defined community-based cohort and followed up for an average of 5 years. BMI and blood lipids were measured at baseline and follow-up.
The association of each rs662799 A-allele with risk of incident dyslipidemia was stronger along with the increase in BMI change level, with the odds ratios (OR) increasing from 1.03 in the lowest tertile of BMI change (< 0.02 kg/m2) to 1.17 in the second (0.02-1.29), and 1.46 in the highest tertile (> 1.29) (pfor interaction< 0.001). Associations of each 1-unit of BMI (kg/m2) increase with incident dyslipidemia were more prominent in the AA carriers (OR = 1.50, 95%CI [1.26-1.80], p < 0.001), while much weaker in the GA (OR = 1.10) or GG carriers (OR = 1.09) (pfor interaction = 0.002). Similar results were found for the risk of incident higher triglycerides (TG) and lower high-density lipoprotein cholesterol (HDL-c), or the longitudinal changes in log10-TG (all pfor interaction ≤ 0.02).
BMI changes significantly modulate rs662799 genetic contribution to dyslipidemia and long-term lipid profile, which provide new evidence for personalized clinical management of lipids according to individual genetic background.

Myocardial infarction (MI), a leading cause of death around the world, displays a complex pattern of inheritance. Previously, rare mutations in low-density lipoprotein receptor (LDLR) genes and apolipoprotein A V (APOA5) have been shown to contribute to MI risk in individual families. Exosomes provide a potential source of biomarkers for MI. This study is to determine the role of LDLR and APOA5 as biomarkers for early diagnosis of MI.
In this study, we detected the levels of LDLR, APOA5, and cardiac troponin T in plasma-derived exosomes in MI patients and age-matched healthy people by enzyme linked immunosorbent assay and observed the morphology and number of exosomes using transmission electron microscope and nanoparticle tracking analysis. Oxygen-glucose deprivation (OGD) method was used to induce MI in H9C2 cardiomyocytes to explore the effect of exosomes.
We found that the levels of LDLR and APOA5 in plasma-derived exosomes in MI patients were significantly decreased. Furthermore, exosomes of MI patients were significantly larger in size and the concentration of exosomes was higher than that of age-matched non-MI people. In vitro experiments showed that OGD treatment induced apoptosis of myocardial cells and decreased the expression of LDLR and APOA5, while addition of exosomes isolated from healthy people rescued these phenotypes.
Exosomal APOA5 and LDLR are intimately associated with MI, and thereby have the potential to function as diagnostic markers of MI.