Dual-target inhibitors of bromodomain-containing protein 4 (BRD4) in cancer therapy: Current situation and future directions

Bromodomain-containing protein 4 (BRD4) is emerging as a therapeutic target that acts synergistically with other targets of small-molecule drugs in cancer. Therefore, the discovery of potential new dual-target inhibitors of BRD4 may be a promising strategy for cancer therapy. In this review, we highlight a series of strategies to design therapeutic dual-target inhibitors of BRD4 that focus on the synergistic functions of this protein. Drug combinations that exploit synthetic lethality, protein–protein interactions, functional complementarity, and blocking of resistance mechanisms could ultimately overcome the barriers inherent to the development of BRD4 inhibitors as future cancer drugs.     

The rationale for mTOR inhibition in epithelial ovarian cancer

The AKT/mTOR signaling pathway is frequently overexpressed in human epithelial ovarian cancer and an attractive target for therapy. In vivo mouse models were confirmative for in vitro findings, where the administration of mTOR inhibitors in ovarian cancer xenografts showed antitumoral as well as antiangiogenic effects. Phase I – II trials are now ongoing with mTOR inhibitors in ovarian cancer patients, some in combination with conventional cytotoxic agents. If further development of mTOR inhibition in ovarian cancer is pursued, studying combinations of mTOR inhibitors with other new targeted therapies would be of interest. mTOR inhibitors in the adjuvant setting could have potential, since, for the moment, there is no standard maintenance therapy in ovarian cancer. A crucial challenge will be to identify strong predictive biomarkers. This review highlights the rationale for the use of mTOR inhibitors in ovarian cancer and summarizes the available preclinical findings.     

Associations of multiple unhealthy lifestyle behaviors with overweight/obesity and abdominal obesity among Brazilian adolescents: A country-wide survey

Background and Aims

Physical inactivity, unhealthy diet, smoking and heavy drinking are four key unhealthy lifestyle behaviors (ULB) that may influence body weight and obesity development. More recently, sedentary time has been recognized as another potentially emerging ULB related to obesity. We therefore investigated the association of multiple ULB with overweight/obesity and abdominal obesity among Brazilian adolescents.

PI3K-mTOR信号通路抑制剂抗肿瘤研究新进展

PI3K是一种脂质激酶,控制着细胞生长、增殖、迁移、存活和血管生成,以及通过激活磷脂酰肌醇3-激酶(PI3K)、AKT和雷帕霉素靶蛋白(mTOR)促进肿瘤发展。哺乳动物mTOR的作用靶点是一种丝氨酸/苏氨酸蛋白激酶,它在细胞中广泛地表达,是一种治疗癌症的靶向目标。本文将主要论述癌症细胞系PI3K-mTOR信号通路的改变,包括乳腺癌、前列腺癌、肺癌、胰腺癌、肝癌等的作用机制。PI3K-mTOR是肿瘤治疗的有前途的靶向目标。多靶点抑制是肿瘤治疗最有效的方法,通过讨论临床试验中研究的PI3K-mTOR抑制剂药物,为将来临床抗肿瘤药物的研发提供新途径。     

The anti-fibrotic effects of epigallocatechin-3-gallate in bile duct-ligated cholestatic rats and human hepatic stellate LX-2 cells are mediated by the PI3K/Akt/Smad pathway

Aim:

(−)-Epigallocatechin-3-gallate (EGCG) is one of the most abundant polyphenols in green tea with strong antioxidant activity and various therapeutic effects. In this study, we investigated the anti-fibrotic effects of EGCG and underlying mechanisms in bile duct-ligated (BDL) rats and a liver fibrosis model in vitro.

Methods:

BDL rats were treated with EGCG (25 mg·kg⁻¹·d⁻¹, po) for 14 d, and then the serum, bile and liver samples were collected. Liver fibrosis was assessed by serum, urine and bile biochemistry analyses and morphological studies of liver tissues. TGF-β1-stimulated human hepatic stellate LX-2 cells were used as a liver fibrosis model in vitro. The expression of liver fibrogenic genes and signaling proteins in the PI3K/Akt/Smad pathway was examined using Western blotting and/or real-time PCR.

Results:

In BDL rats, EGCG treatment significantly ameliorates liver necrosis, inflammation and fibrosis, and suppressed expression of the genes associated with liver inflammation and fibrogenesis, including TNF-α, IL-1β, TGF-β1, MMP-9, α-SMA, and COL1A1. In LX-2 cells, application of EGCG (10, 25 μmol/L) dose-dependently suppressed TGF-β1-stimulated expression of COL1A1, MMP-2, MMP-9, TGF-β1, TIMP1, and α-SMA. Furthermore, EGCG significantly suppressed the phosphorylation of Smad2/3 and Akt in the livers of BDL rats and in TGF-β1-stimulated LX-2 cells. Application of {"type":"entrez-nucleotide","attrs":{"text":"LY294002","term_id":"1257998346","term_text":"LY294002"}}LY294002, a specific inhibitor of PI3K, produced similar effects as EGCG did in TGF-β1-stimulated LX-2 cells, but co-application of EGCG and {"type":"entrez-nucleotide","attrs":{"text":"LY294002","term_id":"1257998346","term_text":"LY294002"}}LY294002 did not produce additive effects.

Conclusion:

EGCG exerts anti-fibrotic effects in BDL rats and TGF-β1-stimulated LX-2 cells in vitro via inhibiting the PI3K/Akt/Smad pathway.     

Impaired degradation and aberrant phagocytosis of necrotic cell debris in the peripheral blood of patients with primary Sjögren's syndrome

Aberrant removal of necrotic debris is considered a feature with inflammatory consequences in SLE. Herein, primary Sjögren's syndrome (SS) patients were investigated for the first time for the capacity of their sera to degrade secondary necrotic cell remnants (SNEC) and DNA (endonuclease DNase1 activity), as well as for uptake of SNEC by blood-borne phagocytes. For comparison, specimens from unselected SLE and RA patients and from healthy blood donors (HBD) were also studied. Compared to HBD, the sera from SS and SLE patients studied (but not RA) were found to exhibit significantly impaired capacity for degradation of SNEC (both for p = 0.007) and deficient DNase1 activity (both for p < 0.0001). The deficient DNase1 activity in SS and SLE sera did not owe to decreased DNase1 protein levels. It correlated inversely with increased serum levels of circulating nucleosomes and cell-free DNA (p < 0.0001), as well as with the disease activity indices of SS (r = −0.445, p = 0.0001) and SLE (r = −0.500, p = 0.013). In ex-vivo whole blood analyses, SS and SLE patients (but not RA) also manifested significantly increased SNEC-phagocytosis by monocytes and granulocytes (all for p < 0.0001) that also correlated with disease severity indices of SS (p = 0.001) and SLE (p = 0.01). In various cross-admixture experiments, such aberration was found to reside in the hyperfunctional activity of phagocytes, the impaired degrading activity of serum DNase1 and the SNEC-binding capacity of serum IgG of SS and SLE patients. The sera of SS and SLE patients (but not of RA) induced significant SNEC-phagocytosis by healthy monocytes that correlated inversely with the DNase1 activity (r = −0.634, p < 0.0001) of these sera. In line with this, the inhibition of DNase1 in HBD sera by G-actin was found to lead to significantly diminished SNEC degradation and increased SNEC uptake by healthy phagocytes (p = 0.0009), supporting the important physiologic role of serum DNase1 in the prevention of SNEC-phagocytosis. Purified serum IgG preparations from SS and SLE patients manifested increased binding to SNEC and were able to enhance significantly the engulfment of SNEC by healthy phagocytes both directly (under serum-free conditions, p ≤ 0.009) and via the prevention of physiologic degradation of SNEC by serum, most likely due to their “shielding” against endonuclease digestion (p = 0.0005). These data indicate that upon cell necrosis, the immune system of SS and SLE patients may be overly exposed to the necrotic debris, a fact that probably holds a key role in the pathogenesis of inflammatory and autoimmune reactions observed in these disorders.     

桔皮素对人非小细胞肺癌细胞生长及侵袭的影响

目的:探讨桔皮素(TGN)对非小细胞肺癌(NSCLC)细胞生长和侵袭的影响及其分子机制。方法:体外培养非小细胞肺癌A549细胞,分别用不同浓度的TGN处理,MTT比色法检测细胞活性,Annexin V-FITC/PI染色及流式细胞术检测细胞凋亡率,Transwell检测细胞侵袭,RT-PCR分析MMP-2和MMP-9的mRNA表达水平,Western blotting检测Ki67、Cyt C、caspase-3、cleaved caspase-3、MMP-2、MMP-9、Akt、p-Akt以及p-PI3K表达水平。结果:桔皮素剂量依赖性地抑制A549细胞增殖(P0.05),同时伴随有增殖标记分子Ki67表达水平的下调。分析发现,桔皮素诱导细胞中Cyt C、caspase-3和cleaved caspase-3的表达上调(P0.01),加速A549细胞的凋亡。此外,桔皮素作用后,A549细胞中侵袭相关蛋白MMP-2和MMP-9的表达量下降,且侵袭数目随桔皮素浓度增加而减少。进一步研究表明,桔皮素作用后A549细胞中p-Akt和p-PI3K表达水平降低(P0.05),阻断PI3K/Akt信号通路后,不同浓度TGN对细胞活性影响没有变化。结论:桔皮素能抑制A549细胞生长及侵袭,促进细胞凋亡,可能通过抑制PI3K/Akt信号通路的激活起作用。因此,本研究将为非小细胞肺癌的防治提供新的研究方向。     

PI3K/PKB信号通路在TGF-β_1诱导人肝星状细胞表达骨桥蛋白中的作用

目的:研究磷脂酰肌醇3-激酶/蛋白激酶B(PI3K/PKB)信号通路在转化生长因子β1(TGF-β1)诱导人肝星状细胞表达骨桥蛋白(OPN)的调控作用。方法:体外培养LX-2人肝星状细胞株,予TGF-β1(终浓度2.5、5、10、20μg/L)刺激24 h或予TGF-β1(终浓度10μg/L)刺激12 h、24 h、48 h;先经PI3K/PKB信号通路特异性抑制剂wortmannin(0.1μmol/L)预处理1 h,再予10μg/L TGF-β1刺激24 h,收集细胞,采用real-time PCR及Western blotting法检测OPN表达情况。结果:TGF-β1能够促进LX-2细胞表达OPN,在一定浓度和时间范围内,其表达量随着TGF-β1浓度和时间的增加而增加,呈剂量和时间依赖性关系;经wortmannin预处理再予TGF-β1刺激的LX-2细胞,与对照组相比,OPN表达受到明显抑制(P0.01)。结论:TGF-β1对LX-2人肝星状细胞OPN表达具有诱导作用,此作用可能受PI3K/PKB信号通路的调控。     

DHA通过抑制PI3K通路和GLUT2表达而诱导NSCLC细胞毒性

目的:研究二氢青蒿素(dihydroartemisinin,DHA)诱导NSCLC细胞毒性的分子机制。方法:将不同浓度的DHA作用NSCLC细胞系A549和NCI-H1650细胞不同时间,运用MTT法、克隆形成实验、Annexin V染色和流式细胞术测定DHA对细胞活力、克隆形成能力和细胞凋亡的影响;同时测定DHA对细胞中葡萄糖水平、ATP和乳酸含量的影响;Western blot检测PI3K通路活性和GLUT2表达变化;通过细胞转染实现葡萄糖转运体2(GLUT2)和Rheb在A549和NCI-H1650细胞中高表达,测定和分析DHA作用下细胞活力、细胞凋亡、葡萄糖水平、ATP含量和PI3K通路活性的变化;分析葡萄糖缺乏对DHA诱导NSCLC细胞毒性的影响。结果:与对照组比较,DHA显著抑制A549和NCI-H1650细胞活力和克隆形成能力以及诱导细胞凋亡,同时降低ATP和乳酸含量以及抑制细胞对葡萄糖的摄取,具有时间和剂量依赖效应。Western blot结果显示,DHA能抑制PI3K通路活性和GLUT2的表达。上调GLUT2的表达和激活PI3K通路能减弱DHA对NSCLC细胞的毒性作用;葡萄糖缺乏能增强DHA对NSCLC细胞的毒性;相反,高浓度葡萄糖则抑制DHA对NSCLC细胞的毒性。结论:DHA能抑制NSCLC细胞活力和克隆形成,诱导细胞凋亡,该作用是通过降低PI3K活性和GLUT2的表达进而抑制细胞糖酵解代谢实现的。