Repurposing of Clinically Developed Drugs for Treatment of Middle East Respiratory Syndrome Coronavirus Infection

Outbreaks of emerging infections present health professionals with the unique challenge of trying to select appropriate pharmacologic treatments in the clinic with little time available for drug testing and development. Typically, clinicians are left with general supportive care and often untested convalescent-phase plasma as available treatment options. Repurposing of approved pharmaceutical drugs for new indications presents an attractive alternative to clinicians, researchers, public health agencies, drug developers, and funding agencies. Given the development times and manufacturing requirements for new products, repurposing of existing drugs is likely the only solution for outbreaks due to emerging viruses. In the studies described here, a library of 290 compounds was screened for antiviral activity against Middle East respiratory syndrome coronavirus (MERS-CoV) and severe acute respiratory syndrome coronavirus (SARS-CoV). Selection of compounds for inclusion in the library was dependent on current or previous FDA approval or advanced clinical development. Some drugs that had a well-defined cellular pathway as target were included. In total, 27 compounds with activity against both MERS-CoV and SARS-CoV were identified. The compounds belong to 13 different classes of pharmaceuticals, including inhibitors of estrogen receptors used for cancer treatment and inhibitors of dopamine receptor used as antipsychotics. The drugs identified in these screens provide new targets for in vivo studies as well as incorporation into ongoing clinical studies.     

Molecular targets for cancer therapy in the PI3K/AKT/mTOR pathway

Aberrations in various cellular signaling pathways are instrumental in regulating cellular metabolism, tumor development, growth, proliferation, metastasis and cytoskeletal reorganization. The fundamental cellular signaling cascade involved in these processes, the phosphatidylinositol 3-kinase/protein kinase-B/mammalian target of rapamycin (PI3K/AKT/mTOR), closely related to the mitogen-activated protein kinase (MAPK) pathway, is a crucial and intensively explored intracellular signaling pathway in tumorigenesis. Various activating mutations in oncogenes together with the inactivation of tumor suppressor genes are found in diverse malignancies across almost all members of the pathway. Substantial progress in uncovering PI3K/AKT/mTOR alterations and their roles in tumorigenesis has enabled the development of novel targeted molecules with potential for developing efficacious anticancer treatment. Two approved anticancer drugs, everolimus and temsirolimus, exemplify targeted inhibition of PI3K/AKT/mTOR in the clinic and many others are in preclinical development as well as being tested in early clinical trials for many different types of cancer. This review focuses on targeted PI3K/AKT/mTOR signaling from the perspective of novel molecular targets for cancer therapy found in key pathway members and their corresponding experimental therapeutic agents. Various aberrant prognostic and predictive biomarkers are also discussed and examples are given. Novel approaches to PI3K/AKT/mTOR pathway inhibition together with a better understanding of prognostic and predictive markers have the potential to significantly improve the future care of cancer patients in the current era of personalized cancer medicine.     

槲皮素通过PI3K/AKT/mTOR通路减轻脓毒症小鼠心肌损伤

目的基于磷脂酰肌醇-3激酶(PI3K)/蛋白激酶B(AKT)/哺乳动物雷帕霉素靶蛋白(mTOR)通路探究槲皮素减轻脓毒症小鼠心肌损伤的分子机制,为槲皮素治疗脓毒症提供理论依据。方法采用盲肠结扎穿孔法构建脓毒症小鼠模型,将造模成功的小鼠随机分为模型组、槲皮素组(200 mg/kg)、抑制剂组(PI3K/mTOR抑制剂NVP-BEZ235 60 mg/kg)和槲皮素+抑制剂组(槲皮素200 mg/kg+PI3K/mTOR抑制剂NVP-BEZ235 60 mg/kg),每组15只,另取15只小鼠作为假手术组。假手术组和模型组小鼠灌胃等体积生理盐水,其余各组灌胃相对应药物,给药体积10 m L/kg。给药24 h后,超声检测平均动脉压(MAP)、左心室收缩压(LVSP)、左心室等容舒张期压力下降最大速率(-dp/dtmax)和左心室等容舒张期压力上升最大速率(+dp/dtmax);全自动生化分析仪检测血清肌酸激酶同工酶(CK-MB)和心肌肌钙蛋白I(cTnI)水平;苏木素-伊红(HE)染色观察心肌组织病理学变化;酶联免疫吸附(ELISA)法检测心肌组织白细胞介素-6(IL-6)、肿瘤坏死因子-α(TNF-α)、丙二醛(MDA)和超氧化物歧化酶(SOD)含量;蛋白免疫印迹(Western blot)法检测心肌组织PI3K、AKT和mTOR蛋白磷酸化水平。结果心肌组织病理损伤:模型组小鼠心肌组织出现结构紊乱、心肌细胞变性、心肌纤维断裂、心肌横纹模糊、细胞间质水肿等病理损伤;槲皮素组较模型组减轻,抑制剂组较模型组加重;槲皮素+抑制剂组较槲皮素组加重。MAP、LVSP、-dp/dtmax、+dp/dtmax、SOD含量及PI3K、AKT、mTOR蛋白磷酸化水平:模型组较假手术组降低;槲皮素组较模型组升高,抑制剂组较模型组降低;槲皮素+抑制剂组较槲皮素组降低,较抑制剂组升高,差异均有统计学意义(P <0.05)。CK-MB、cTnI水平及TNF-α、IL-6、MDA含量:模型组较假手术组升高;槲皮素组较模型组降低,抑制剂组较模型组升高;槲皮素+抑制剂组较槲皮素组升高,较抑制剂组降低,差异均有统计学意义(P <0.05)。结论槲皮素可能通过上调PI3K/AKT/mTOR通路降低脓毒症小鼠心肌组织炎症和氧化应激反应,从而减轻心肌损伤。     

FK228 augmented temozolomide sensitivity in human glioma cells by blocking PI3K/AKT/mTOR signal pathways

Temozolomide is a novel cytotoxic agent currently used as first-line chemotherapy for glioblastoma multiforme (GBM). Romidepsin (FK228), a histone deacetylase inhibitor, is a promising new class of antineoplastic agent with the capacity to induce growth arrest and/or apoptosis of cancer cells. However, combination of the two drugs in glioma remains largely unknown. In the present study, we evaluated the combinatory effects of FK228 with TMZ in glioma, and its molecular mechanisms responsible for these effects. Glioma cell lines were treated with TMZ, FK228 or the combination of drugs. The resistance effect including cytotoxicity and apoptosis was determined in glioma cells, respectively. We further evaluated the effects of FK228 in the PI3K/Akt-signaling pathway in vitro. Mice engrafted with 5 × 10⁶ LN382 cells were treated with TMZ, FK228 or the combination of two drugs, and tumor weights and volumes were measured, respectively. FK228 enhanced the cytotoxic effects of TMZ in glioma cells compared to vehicle-treated controls or each drug alone. The combination of FK228 and TMZ-induced apoptosis was demonstrated by increased expression of cleaved-Caspase 3, Bax, cleaved-PARP, and decreased Bcl-2 expression. Furthermore, the expression of key components of the PI3K/Akt-signaling pathway showed that combination of FK228 and TMZ block PI3K/Akt pathways in vitro. This block effect was also confirmed in vivo in mice models. Mice treated with both FK228 and TMZ drugs showed significantly reduced tumor weights and volumes, compared to each drug alone. Our results suggested that FK228 augmented temozolomide sensitivity in human glioma cells partially by blocking PI3K/AKT/mTOR signal pathways. It thus may provide a promising target for improving the therapeutic outcome of TMZ-resistant gliomas, although further studies will be needed.     

PDGFRs are critical for PI3K/Akt activation and negatively regulated by mTOR

The receptor tyrosine kinase/PI3K/Akt/mammalian target of rapamycin (RTK/PI3K/Akt/mTOR) pathway is frequently altered in tumors. Inactivating mutations of either the TSC1 or the TSC2 tumor-suppressor genes cause tuberous sclerosis complex (TSC), a benign tumor syndrome in which there is both hyperactivation of mTOR and inhibition of RTK/PI3K/Akt signaling, partially due to reduced PDGFR expression. We report here that activation of PI3K or Akt, or deletion of phosphatase and tensin homolog (PTEN) in mouse embryonic fibroblasts (MEFs) also suppresses PDGFR expression. This was a direct effect of mTOR activation, since rapamycin restored PDGFR expression and PDGF-sensitive Akt activation in Tsc1-/- and Tsc2-/- cells. Akt activation in response to EGF in Tsc2-/- cells was also reduced. Furthermore, Akt activation in response to each of EGF, IGF, and PMA was reduced in cells lacking both PDGFRalpha and PDGFRbeta, implying a role for PDGFR in transmission of growth signals downstream of these stimuli. Consistent with the reduction in PI3K/Akt signaling, in a nude mouse model both Tsc1-/- and Tsc2-/- cells had reduced tumorigenic potential in comparison to control cells, which was enhanced by expression of either active Akt or PDGFRbeta. In conclusion, PDGFR is a major target of negative feedback regulation in cells with activated mTOR, which limits the growth potential of TSC tumors.     

LINC00941 promoted in vitro progression and glycolysis of laryngocarcinoma by upregulating PKM via activating the PI3K/AKT/mTOR signaling pathway

BackgroundLINC00941 has been proved to be related to various tumors, but its relationship with laryngocarcinoma remains vague.MethodsLINC00941 expression in laryngocarcinoma tumor and laryngocarcinoma cells was determined by real time‐quantitative polymerase chain reaction (RT‐qPCR). Besides, the five‐year survival of laryngocarcinoma patients with different LINC00941 expression was analyzed with Kaplan–Meier survival analysis, and the clinical characteristics of laryngocarcinoma patients were also recorded. After transfection, cell viability, cell proliferation, apoptosis, cell cycle, migration, and invasion were detected by cell counting kit‐8 (CCK‐8), colony formation, flow cytometry, cell scratch, and Transwell assays, respectively. Glycolysis was assessed by the colorimetric method. Expressions of proliferation‐associated proteins, migration‐associated proteins, glycolysis‐associated proteins, and phosphatidylinositol 3‐kinase (PI3K)/AKT/mammalian target of rapamycin (mTOR) signal pathway‐associated proteins were detected by Western blot.ResultsIn laryngocarcinoma tumor tissues and cells, LINC00941 was highly expressed. High expression of LINC00941 decreased the 5‐year survival of laryngocarcinoma patients, and it was positively related to lymph node metastasis and clinical stages. LINC00941 overexpression decreased apoptosis but promoted cell viability, proliferation, cell‐cycle progression, migration, and invasion, and glucose consumption and lactate production in laryngocarcinoma cells. Moreover, LINC00941 overexpression elevated expressions of Ki‐67, PCNA, MMP2, N‐Cadherin, HK2, PFKFB4, and PKM, activated the PI3K/AKT/mTOR signal pathway but reduced E‐Cadherin expression, while LINC00941 silencing had the opposite effects. PKM overexpression reversed the effects of LINC00941 silencing on cellular and glycolytic phenotypes.ConclusionLINC00941 promoted in vitro progression and glycolysis of laryngocarcinoma cells by upregulating PKM via activating the PI3K/AKT/mTOR signaling pathway.     

天麻素干预对过氧化氢诱导的PC12细胞凋亡、活力及PI3K／AKT信号通路蛋白的影响

【目的】探讨磷脂酰肌醇3激酶（PI3K）蛋白表达量及蛋白激酶 B（AKT ）信号通路在过氧化氢（H2 O2）诱导的 PC12细胞中的作用及天麻素的干预对其通路的影响。【方法】PC12细胞随机分为正常对照组,模型组（400μmol／L H2 O2）,天麻素低、中、高浓度组（0．1、1、10μmol／L 天麻素＋400μmol／L H2 O2）。咪唑蓝法检测各组细胞活力,Hoechst 染色观察各组细胞凋亡情况,比色法检测天冬氨酸蛋白水解酶（Caspase 3）、Caspase 8及 Caspase 9活性,western blot 分析 Bcl‐2、Bax 及 PI3K 蛋白表达量与 AKT 磷酸化水平。【结果】与正常对照组比较,模型组中细胞活力下降,细胞凋亡率提高,Caspase 3、Caspase 8及 Caspase 9活性提高,Bcl‐2及 PI3K 表达量下降,Bax 表达量上升,AKT 磷酸化水平降低,差异均具有统计学意义（ P ＜0．01）;与模型组比较,天麻素低、中、高浓度组细胞活力提高,细胞凋亡率降低,Caspase 3、Caspase 8及 Caspase 9活性降低,Bcl‐2、PI3K 蛋白表达量及 AKT 磷酸化水平提高,天麻素中、高浓度组 Bax 表达量降低,差异均具有统计学意义（ P ＜0．01）。【结论】天麻素可通过激活 PI3K／AKT 信号通路,从而抑制 H2 O2诱导的 PC12细胞凋亡。     

The m6A methyltransferase METTL14 inhibits the proliferation,migration, and invasion of gastric cancer by regulating the PI3K/AKT/mTOR signaling pathway

Background N6‐methyladenosine (m6A) modification may participate in the regulation of occurrence and development of tumors. However, the m6A level and the potential regulatory mechanism of m6A in gastric cancer (GC) remain uncertain.MethodsRNA m6A quantification assay was conducted to detect the m6A level in GC tissues and cell lines. Methyltransferase‐like 14 (METTL14) expression in GC tissues was explored by bioinformatics and immunohistochemistry. Then, the function of METTL14 in GC cells was examined by CCK‐8, colony formation assay, wound healing assay, and Transwell assay. Besides, Western blotting was conducted to probe the PI3K/AKT/mTOR pathway and the epithelial‐mesenchymal transformation (EMT) pathway‐related gene expression.ResultsThe m6A modification level was decreased in GC and METTL14 was a key regulator resulting in m6A disorder in GC. METTL14 was downregulated in GC by analyzing both clinical samples and bioinformatics. METTL14 overexpression suppressed GC cell proliferation and aggression by deactivating the PI3K/AKT/mTOR pathway and the EMT pathway, respectively.ConclusionsOur findings indicate that METTL14 partakes in the biological process of GC as a tumor suppressor and may be an emerging biomarker in GC.