4-苯基丁酸类似物的设计合成及对PC12细胞内质网应激与过度自噬的抑制作用

目的：设计合成4-苯基丁酸（PBA）类似物并探究其对PC12细胞内质网应激（ERS）和过度自噬的双重抑制作用。方法：以PBA为母核，设计合成了11个PBA类似物（A1-A11），通过1H NMR、13C NMR、MS确证化学结构，采用MTT法分析化合物A1-A11对毒胡萝卜素（TG）诱导的PC12细胞ERS损伤模型和H2O2诱导的PC12细胞过度自噬损伤模型中细胞的保护作用；Western blot法检测ERS的标志蛋白葡萄糖调节蛋白78（GRP78）和自噬标志蛋白LC3 II/I和Beclin-1表达水平。结果：共合成了11 个PBA类似物，其中A3、A7、A9-A11为新化合物。MTT法结果表明，PBA类似物A1对TG诱导的ERS损伤细胞具有保护作用（P ＜0.05）。A1、A2、A4 和A6-A10对H2O2诱导的过度自噬损伤细胞均有良好的保护活性（P ＜0.05）。Western blot检测结果表明，A1能显著抑制ERS标志性蛋白GRP78、自噬标志性蛋白LC3 II/I和Beclin-1 的表达水平（P ＜0.05）。结论：与PBA相比，设计合成的化合物A1对ERS和过度自噬的损伤细胞具有最强的双重保护作用。     

内质网应激对肿瘤发生发展的影响及中医药的干预作用

内质网是真核细胞内负责蛋白质、类固醇、脂类和糖类合成以及钙依赖性信号转导的重要细胞器，内质网稳态对维持机体正常功能具有重要意义。内质网稳态失衡可诱发内质网应激（ERS），参与消化系统、呼吸系统、循环系统、神经系统、生殖系统和内分泌系统等疾病的发生与发展，影响机体健康。在众多疾病中，肿瘤的致死率、致残率和复发率均较高，严重危及国民健康。因异于正常细胞的无限增殖的生存特点，肿瘤细胞常暴露于缺氧、缺血、增殖过度、饥饿等各种内外刺激中，导致细胞内蛋白质平衡遭到破坏，存在一定程度ERS，以促进自身存活。研究表明，ERS在多种肿瘤中扮演重要角色，对肿瘤细胞的生存具有双重作用，既可通过激活一系列适应性反应促进肿瘤细胞生存，又可诱发ERS相关凋亡通路，促进肿瘤细胞死亡，抑制肿瘤生长和侵袭。而随着ERS在肿瘤中的多种作用不断被报道，较多学者已尝试从ERS的角度干预肿瘤的进展。中医药对肿瘤的治疗作用已得到广泛认可，能从多个方面参与肿瘤的调节，包括ERS，放化疗抵抗，化疗致胃肠道不良反应，术后复发和转移等。但目前，从ERS角度探究中医药抗肿瘤作用报道相对较少。鉴于此，本文从ERS对肿瘤发生发展的影响和中医药经ERS干预肿瘤的进展2个方面进行阐述，以期为肿瘤的治疗提供新的方向。     

KLF4-SQSTM1/p62-associated prosurvival autophagy contributes to carfilzomib resistance in multiple myeloma models

Multiple myeloma (MM) is an incurable clonal plasma cell malignancy. Because of a high rate of immunoglobulin synthesis, the endoplasmic reticulum of MM cells is subjected to elevated basal levels of stress. Consequently, proteasome inhibitors, which exacerbate this stress by inhibiting ubiquitin-proteasome-mediated protein degradation, are an important new class of chemotherapeutic agents being used to combat this disease. However, MM cells still develop resistance to proteasome inhibitors such as carfilzomib. Toward this end, we have established carfilzomib-resistant derivatives of MM cell lines. We found that resistance to carfilzomib was associated with elevated levels of prosurvival autophagy, and Kruppel-like factor 4 (KLF4) was identified as a contributing factor. Expression levels as well as nuclear localization of KLF4 protein were elevated in MM cells with acquired carfilzomib resistance. Chromatin immunoprecipitations indicated that endogenous KLF4 bound to the promoter regions of the SQSTM1 gene encoding the ubiquitin-binding adaptor protein sequestosome/p62 that links the proteasomal and autophagic protein degradation pathways. Ectopic expression of KLF4 induced upregulation of SQSTM1. On the other hand, inhibitors of autophagy sensitized MM cells to carfilzomib, even in carfilzomib-resistant derivatives having increased expression of the multidrug resistance protein P-glycoprotein. Thus, we report here a novel function for KLF4, one of the Yamanaka reprogramming factors, as being a contributor to autophagy gene expression which moderates preclinical proteasome inhibitor efficacy in MM.     

The different roles of selective autophagic protein degradation in mammalian cells

Autophagy is an intracellular pathway for bulk protein degradation and the removal of damaged organelles by lysosomes. Autophagy was previously thought to be unselective; however, studies have increasingly confirmed that autophagy-mediated protein degradation is highly regulated. Abnormal autophagic protein degradation has been associated with multiple human diseases such as cancer, neurological disability and cardiovascular disease; therefore, further elucidation of protein degradation by autophagy may be beneficial for protein-based clinical therapies. Macroautophagy and chaperone-mediated autophagy (CMA) can both participate in selective protein degradation in mammalian cells, but the process is quite different in each case. Here, we summarize the various types of macroautophagy and CMA involved in determining protein degradation. For this summary, we divide the autophagic protein degradation pathways into four categories: the post-translational modification dependent and independent CMA pathways and the ubiquitin dependent and independent macroautophagy pathways, and describe how some non-canonical pathways and modifications such as phosphorylation, acetylation and arginylation can influence protein degradation by the autophagy lysosome system (ALS). Finally, we comment on why autophagy can serve as either diagnostics or therapeutic targets in different human diseases.     

Involvement of autophagy in melatonin‐induced cytotoxicity in glioma‐initiating cells

Glioblastoma‐initiating cells (GICs) represent a stem cell‐like subpopulation within malignant glioblastomas responsible for tumor development, progression, therapeutic resistance, and tumor relapse. Thus, eradication of this subpopulation is essential to achieve stable, long‐lasting remission. We have previously reported that melatonin decreases cell proliferation of glioblastoma cells both in vitro and in vivo and synergistically increases effectiveness of drugs in glioblastoma cells and also in GICs. In this study, we evaluated the effect of the indolamine alone in GICs and found that melatonin treatment reduces GICs proliferation and induces a decrease in self‐renewal and clonogenic ability accompanied by a reduction in the expression of stem cell markers. Moreover, our results also indicate that melatonin treatment, by modulating stem cell properties, induces cell death with ultrastructural features of autophagy. Thus, data reported here reinforce the therapeutic potential of melatonin as a treatment of malignant glioblastoma both by inhibiting tumor bulk proliferation or killing GICs, and simultaneously enhancing the effect of chemotherapy.     

Thyroid Hormones and Cardiovascular Function and Diseases

Thyroid hormone (TH) receptors are present in the myocardium and vascular tissue, and minor alterations in TH concentration can affect cardiovascular (CV) physiology. The potential mechanisms that link CV disease with thyroid dysfunction are endothelial dysfunction, changes in blood pressure, myocardial systolic and diastolic dysfunction, and dyslipidemia. In addition, cardiac disease itself may lead to alterations in TH concentrations (notably, low triiodothyronine syndrome) that are associated with higher morbidity and mortality. Experimental data and small clinical trials have suggested a beneficial role of TH in ameliorating CV disease. The aim of this review is to provide clinicians dealing with CV conditions with an overview of the current knowledge of TH perturbations in CV disease.     

Nerve alterations showing autophagy in 2 patients with lichen aureus

Lichen aureus is a rare, chronic, persistent purpuric dermatosis clinically characterized by striking yellow‐ to bronze‐colored lesions. Histologically, lichen aureus differs from other pigmented purpuric dermatoses in containing dense, band‐like infiltrates closely associated with the epidermis. This report describes 2 patients with lichen aureus, a 20‐year‐old woman with a lesion on her right arm and a 51‐year‐old man with a lesion on the right side of his groin. Skin biopsy specimens revealed almost identical findings in both patients, including dense band‐like infiltrates containing lymphocytes, histiocytes with hemosiderin deposits scattered extravasated red blood cells and nerve alterations at the dermo‐epidermal interface. The nerves within the lesions were filled with granules, which stained positive with antibody to microtubule‐associated protein 1A/1B‐light chain 3, suggesting autophagy within the nerves. These altered nerves were present only in areas of band‐like dermal lymphocytic infiltration. Electron microscopy of the lesions showed the accumulation of autophagosomes in Schwann cells.     

Dysfunctional autophagy in Alzheimer’s disease: pathogenic roles and therapeutic implications

Neuronal autophagy is essential for neuronal survival and the maintenance of neuronal homeostasis. Increasing evidence has implicated autophagic dysfunction in the pathogenesis of Alzheimer’s disease (AD). The mechanisms underlying autophagic failure in AD involve several steps, from autophagosome formation to degradation. The effect of modulating autophagy is context-dependent. Stimulation of autophagy is not always beneficial. During the implementation of therapies that modulate autophagy, the nature of the autophagic defect, the timing of intervention, and the optimal level and duration of modulation should be fully considered.     

骨质疏松中的自噬相关信号通路

骨质疏松症（osteoporosis，OP）是以全身性骨量的丢失、骨微观结构的退行性改变为特征的骨骼疾病，根本原因在于成骨细胞和破骨细胞的动态平衡失调。自噬（Autophagy）能够通过影响成骨和破骨细胞分化的过程改变两者的平衡关系，这就提示我们可以从调控自噬的角度对骨质疏松的病情发展进行干预。本文就自噬的信号通路在骨质疏松症方面的研究进展进行综述，希望为进一步探究自噬信号通路的内在调控机制，选择适当的干预靶点，选择性发挥自噬对成骨、破骨细胞的调节作用，为临床上治疗骨质疏松症提供新的思路。