Due to the advantages in efficacy and safety compared with traditional chemotherapy drugs, targeted therapeutic drugs have become mainstream cancer treatments. Since the first tyrosine kinase inhibitor imatinib was approved to enter the market by the US Food and Drug Administration (FDA) in 2001, an increasing number of small-molecule targeted drugs have been developed for the treatment of malignancies. By December 2020, 89 small-molecule targeted antitumor drugs have been approved by the US FDA and the National Medical Products Administration (NMPA) of China. Despite great progress, small-molecule targeted anti-cancer drugs still face many challenges, such as a low response rate and drug resistance. To better promote the development of targeted anti-cancer drugs, we conducted a comprehensive review of small-molecule targeted anti-cancer drugs according to the target classification. We present all the approved drugs as well as important drug candidates in clinical trials for each target, discuss the current challenges, and provide insights and perspectives for the research and development of anti-cancer drugs.

Metformin is a widely used antidiabetic drug that exerts cardiovascular protective effects in patients with diabetes. How metformin protects against diabetes-related cardiovascular diseases remains poorly understood. Here, we show that metformin abated the progression of diabetes-accelerated atherosclerosis by inhibiting mitochondrial fission in endothelial cells. Metformin treatments markedly reduced mitochondrial fragmentation, mitigated mitochondrial-derived superoxide release, improved endothelial-dependent vasodilation, inhibited vascular inflammation, and suppressed atherosclerotic lesions in streptozotocin (STZ)-induced diabetic ApoE−/− mice. In high glucose–exposed endothelial cells, metformin treatment and adenoviral overexpression of constitutively active AMPK downregulated mitochondrial superoxide, lowered levels of dynamin-related protein (Drp1) and its translocation into mitochondria, and prevented mitochondrial fragmentation. In contrast, AMPK-α2 deficiency abolished the effects of metformin on Drp1 expression, oxidative stress, and atherosclerosis in diabetic ApoE−/−/AMPK-α2−/− mice, indicating that metformin exerts an antiatherosclerotic action in vivo via the AMPK-mediated blockage of Drp1-mediated mitochondrial fission. Consistently, mitochondrial division inhibitor 1, a potent and selective Drp1 inhibitor, reduced mitochondrial fragmentation, attenuated oxidative stress, ameliorated endothelial dysfunction, inhibited inflammation, and suppressed atherosclerosis in diabetic mice. These findings show that metformin attenuated the development of atherosclerosis by reducing Drp1-mediated mitochondrial fission in an AMPK-dependent manner. Suppression of mitochondrial fission may be a therapeutic approach for treating macrovascular complications in patients with diabetes.

Evidence accumulated over the past several years indicates that the AMP-activated protein kinase (AMPK) 2 may be a therapeutic target for treating insulin resistance and type 2 diabetes (1). AMPK is a heterotrimeric protein formed by an ␣ subunit, which contains the catalytic activity, and by the ␤ and ␥ regulatory subunits important in maintaining stability of the heterotrimer complex (2). AMPK belongs to a family of energy-sensing enzymes functioning as a "fuel gauge" that monitors changes in the energy status of a cell (3, 4). When activated, AMPK shuts down anabolic pathways and promotes catabolism in response to an elevated AMP/ATP ratio by down-regulating the activity of several key enzymes of intermediary metabolism (4). Two primary acute consequences of AMPK activation are 1) an increase in glucose uptake by induction of glucose 4 transporter microvesicle cytoplasm to membrane translocation and fusion and 2) an increase in fatty acid oxidation by phosphorylation and inactivation of acetyl-CoA carboxylase (ACC), the rate-limiting enzyme in fatty acid synthesis (5). Therefore, the AMPK signal pathways are thought to play a central role in the regulation of cellular glucose and lipid homeostasis. The control of AMPK activity is complex, and the classic view is that AMPK is activated allosterically by an increase in the intracellular AMP/ATP ratios and/or by the phosphorylation of threonine 172 within the ␣ subunit. Several protein kinases responsible for this phosphorylation have been identified. They include Peutz-Jeghers syndrome kinase LKB1 (LKB1) (6), and the Ca 2ϩ /calmodulin-dependent protein kinase kinase (7). Protein phosphorylation signal transduction systems are balanced and regulated delicately by both phosphatase and kinase. Since AMPK is activated by (a) protein kinase(s) at the threonine 172 residue, one can easily assume that AMPK can be regulated negatively by (a) serine/threonine phosphatase(s). To date, a wide range of physiological stressors, pharmacological agents, and hormones associated with increase in the intracellular AMP/ATP ratios have been demonstrated to activate AMPK (8). AMPK is also thought to be regulated by glycogen (9), which is the major cellular storage form of carbohydrates and thus, an additional indicator of cellular energy status. Lipids are the other major energy source for cellular metabolism. Recent studies (10, 11) in heart and liver have revealed that AMPK may be sensitive to the "lipid status" of a cell, and activation may be influenced by intracellular fatty BSA, bovine serum albumin; eNOS, endothelial nitric-oxide synthase; LKB1, Peutz-Jeghers syndrome kinase LKB1; OA, okadaic acid; ONOO Ϫ , peroxynitrite; VSMC, vascular smooth muscle cell; siRNA, short interference RNA; FFA, free fatty acid; EBM, endothelial basal medium; 2-BrP, 2-bromopalmitate; HFD, high fat diet; PP2C, protein phosphatase 2C.

Thousands of genes have been well demonstrated to play important roles in cancer progression. As genes do not function in isolation, they can be grouped into “networks” based on their interactions. In this study, we discover a network regulating Claudin-4 in gastric cancer. We observe that Claudin-4 is up-regulated in gastric cancer and is associated with poor prognosis. Claudin-4 reinforce proliferation, invasion, and EMT in AGS, HGC-27, and SGC-7901 cells, which could be reversed by miR-596 and miR-3620-3p. In addition, lncRNA-KRTAP5-AS1 and lncRNA-TUBB2A could act as competing endogenous RNAs to affect the function of Claudin-4. Our results suggest that non-coding RNAs play important roles in the regulatory network of Claudin-4. As such, non-coding RNAs should be considered as potential biomarkers and therapeutic targets against gastric cancer.

Smoking is the only modifiable risk factor associated with development, expansion, and rupture of abdominal aortic aneurysm (AAA), a leading cause of death in the human population. However, the causative link between cigarette smoke and AAA remains to be established. Here we report that, like angiotensin II (AngII), acute infusion of nicotine, a major component of cigarette smoke, resulted in significantly increased elastin degradation, enlargement of the aorta, aberrant expression of matrix metalloproteinase 2 (MMP2), and an increased incidence of AAA in ApoE knockout (ApoE−/−) and deficient in both ApoE and AMP-activated kinase (AMPK) α1 subunit (ApoE−/−/AMPKα1−/−) mice. Importantly, genetic deletion of AMPKα2 (ApoE−/−/AMPKα2−/−) markedly reduced the increase of maximal aortic diameter and incidence of AAA caused by nicotine or AngII in vivo. Transplantation of bone marrow cells from ApoE−/− mice into ApoE−/−/AMPKα2−/− mice or vice versa did not alter nicotine/AngII-induced AAA formation. Mechanistically, we found that both nicotine and AngII activated AMPK in cultured vascular smooth muscle cells (VSMC) and increased the nuclear co-localization of AMPKα2 and AP-2α, a key transcriptional factor essential for MMP2 expression. Biochemical and biological analysis revealed that AMPKα2 directly phosphorylated AP-2α at serine 219 and this phosphorylation increased AP-2α-dependent MMP2 gene expression in VSMC. We conclude that nicotine increases the incidence of AAA in vivo through activation of AMPKα2 and AP-2α. Moreover, our results provide the first demonstration of a causative link between nicotine and AAA in vivo.

N 6 -methyladenosine (m 6 A) is the most widespread internal mRNA modification in humans. Despite recent progress in understanding the biological roles of m 6 A, the inability to install m 6 A site-specifically in individual transcripts has hampered efforts to elucidate causal relationships between the presence of a specific m 6 A and phenotypic outcomes. Here we demonstrate that nucleus-localized dCas13 fusions with a truncated METTL3 methyltransferase domain and cytoplasm-localized fusions with a modified METTL3:METTL14 methyltransferase complex can direct site-specific m 6 A incorporation in distinct cellular compartments, with the former fusion protein having particularly low off-target activity. Independent cellular assays across multiple sites confirm that this targeted RNA methylation (TRM) system mediates efficient m 6 A installation in endogenous RNA transcripts with high specificity. Finally, we show that TRM can induce m 6 A-mediated changes to transcript abundance and alternative splicing. These findings establish TRM as a tool for targeted epitranscriptome engineering to help reveal the effect of individual m 6 A modifications and dissect their functional roles.

BackgroundMink enteritis virus (MEV) causes mink viral enteritis, an acute and highly contagious disease whose symptoms include violent diarrhea, and which is characterized by high morbidity and mortality. Nanoparticle-assisted polymerase chain reaction (nanoPCR) is a recently developed technique for the rapid detection of bacterial and viral DNA. Here we describe a novel nanoPCR assay for the clinical detection and epidemiological characterization of MEV.ResultsThis assay is based upon primers specific for the conserved region of the MEV NS1 gene, which encodes nonstructural protein 1. Under optimized conditions, the MEV nanoPCR assay had a detection limit of 8.75 × 101 copies recombinant plasmids per reaction, compared with 8.75 × 103 copies for conventional PCR analysis. Moreover, of 246 clinical mink samples collected from five provinces in North-Eastern China, 50.8% were scored MEV positive by our nanoPCR assay, compared with 32.5% for conventional PCR. Furthermore no cross reactivity was observed for the nanoPCR assay with respect to related viruses, including canine distemper virus (CDV) and Aleutian mink disease parvovirus (AMDV). Phylogenetic analysis of four Chinese wild type MEV isolates using the nanoPCR assay indicated that they belonged to a small MEV clade, named “China type”, in the MEV/FPLV cluster, and were closely clustered in the same location.ConclusionsOur results indicate that the MEV China type clade is currently circulating in domestic minks in China. We anticipate that the nanoPCR assay we have described here will be useful for the detection and epidemiological and pathological characterization of MEV.Electronic supplementary materialThe online version of this article (doi:10.1186/s12917-014-0312-6) contains supplementary material, which is available to authorized users.

In 1900, Adami speculated that a sequence of context-independent energetic and structural changes governed the reversion of differentiated cells to a proliferative, regenerative state. Accordingly, we show here that differentiated cells in diverse organs become proliferative via a shared program. Metaplasia-inducing injury caused both gastric chief and pancreatic acinar cells to decrease mTORC1 activity and massively upregulate lysosomes/autophagosomes; then increase damage associated metaplastic genes such as ; and finally reactivate mTORC1 and re-enter the cell cycle. Blocking mTORC1 permitted autophagy and metaplastic gene induction but blocked cell cycle re-entry at S-phase. In kidney and liver regeneration and in human gastric metaplasia, mTORC1 also correlated with proliferation. In lysosome-defective mice, both metaplasia-associated gene expression changes and mTORC1-mediated proliferation were deficient in pancreas and stomach. Our findings indicate differentiated cells become proliferative using a sequential program with intervening checkpoints: (i) differentiated cell structure degradation; (ii) metaplasia- or progenitor-associated gene induction; (iii) cell cycle re-entry. We propose this program, which we term "paligenosis", is a fundamental process, like apoptosis, available to differentiated cells to fuel regeneration following injury.