Chemical and structural approaches to investigate PTEN function and regulation.

Phosphatase and tensin homolog is a lipid phosphatase that serves as the major negative regulator of the PI3K/AKT pathway. It catalyzes the 3'-specific dephosphorylation of phosphatidylinositol (3,4,5)-trisphosphate (PIP3) to generate PIP2. PTEN's lipid phosphatase function depends on several domains, including an N-terminal segment spanning the first 24 amino acids, which results in a catalytically impaired enzyme when mutated. Furthermore, PTEN is regulated by a cluster of phosphorylation sites located on its C-terminal tail at Ser380, Thr382, Thr383, and Ser385, which drives its conformation from an open to a closed autoinhibited but stable state. Herein, we discuss the protein chemical strategies we used to reveal the structure and mechanism of how PTEN's terminal regions govern its function.

Study on the effect of acupunture treatment on autonomic nerve dysfunction in convalescent period of stroke based on heart rate variability assessment technique.

Stroke patients with autonomic dysfunction are more likely to develop cardiac problems, which have been linked to lower functional outcomes and increased mortality. In this study, heart rate variability (HRV) detection paired with the Clinical Feature Scale will be utilized to elucidate the immediate impact of manual acupuncture on autonomic dysfunction of varying severity in the convalescence stroke phase. This is a randomized, single-blind, controlled clinical trial approach. At a ratio of 1:1, 60 appropriate patients will be randomly randomized into either the experimental or control group. On the basis of symptomatic treatment drugs, the experimental group will additionally undertake acupuncture therapy 3 times a week for 4 weeks, for a total of 12 times. Primary outcomes include 24-hour HRV and 60-minute HRV detection at week 4 compared with baseline. The secondary outcome is the score of clinical feature scale at week 4 compared with the baseline. Adverse events and safety indices will be recorded throughout the experiment. The SPSS V.25.0 statistical program was applied for analysis, and measurement data were expressed as mean ±â€…SD.

Astragaloside regulates lncRNA LOC100912373 and the miR­17­5p/PDK1 axis to inhibit the proliferation of fibroblast­like synoviocytes in rats with rheumatoid arthritis.

Previous studies have confirmed that astragaloside (AST) exerts a positive effect on alleviating synovial and joint injury in rheumatoid arthritis (RA). However, the precise mechanisms through which AST acts in the treatment of RA remain unclear. Long non­coding RNA (lncRNA) LOC100912373 was identified as a key gene related to RA and has been proven to interact with miR­17­5p, in order to regulate the pyruvate dehydrogenase kinase 1 and protein kinase B axis (PDK1/AKT axis). The present study aimed to determine whether AST may treat RA through the interaction between lncRNA LOC100912373 and the miR­17­5p/PDK1 axis. MTT assays and flow cytometry were used to detect the proliferation and cell cycle progression of AST­treated fibroblast­like synoviocytes (FLSs). The expression of lncRNA LOC100912373 and miR­17­5p, as well as relative the mRNA expression of the PDK1 and AKT genes following AST intervention was detected by reverse transcription­quantitative PCR (RT­qPCR), immunofluorescence and western blot analysis. The results revealed that AST inhibited FLS proliferation, reduced lncRNA LOC100912373 expression levels, increased miR­17­5p expression levels, and decreased the PDK1 and p­AKT expression levels. Additionally, consecutive rescue experiments revealed that AST counteracted the effects of lncRNA LOC100912373 overexpression on FLS proliferation and cell cycle progression. On the whole, the present study demonstrates that AST inhibits FLS proliferation by regulating the expression of lncRNA LOC100912373 and the miR­17­5p/PDK1 axis.

MYC Targeted Long Noncoding RNA DANCR Promotes Cancer in Part by Reducing p21 Levels.

The MYC oncogene broadly promotes transcription mediated by all nuclear RNA polymerases, thereby acting as a positive modifier of global gene expression. Here, we report that MYC stimulates the transcription of DANCR, a long noncoding RNA (lncRNA) that is widely overexpressed in human cancer. We identified DANCR through its overexpression in a transgenic model of MYC-induced lymphoma, but found that it was broadly upregulated in many human cancer cell lines and cancers, including most notably in prostate and ovarian cancers. Mechanistic investigations indicated that DANCR limited the expression of cell-cycle inhibitor p21 (CDKN1A) and that the inhibitory effects of DANCR loss on cell proliferation could be partially rescued by p21 silencing. In a xenograft model of human ovarian cancer, a nanoparticle-mediated siRNA strategy to target DANCR in vivo was sufficient to strongly inhibit tumor growth. Our observations expand knowledge of how MYC drives cancer cell proliferation by identifying DANCR as a critical lncRNA widely overexpressed in human cancers.Significance: These findings expand knowledge of how MYC drives cancer cell proliferation by identifying an oncogenic long noncoding RNA that is widely overexpressed in human cancers. Cancer Res; 78(1); 64-74. ©2017 AACR.

Targeted inhibition of tumor-specific glutaminase diminishes cell-autonomous tumorigenesis.

Glutaminase (GLS), which converts glutamine to glutamate, plays a key role in cancer cell metabolism, growth, and proliferation. GLS is being explored as a cancer therapeutic target, but whether GLS inhibitors affect cancer cell-autonomous growth or the host microenvironment or have off-target effects is unknown. Here, we report that loss of one copy of Gls blunted tumor progression in an immune-competent MYC-mediated mouse model of hepatocellular carcinoma. Compared with results in untreated animals with MYC-induced hepatocellular carcinoma, administration of the GLS-specific inhibitor bis-2-(5-phenylacetamido-1,3,4-thiadiazol-2-yl)ethyl sulfide (BPTES) prolonged survival without any apparent toxicities. BPTES also inhibited growth of a MYC-dependent human B cell lymphoma cell line (P493) by blocking DNA replication, leading to cell death and fragmentation. In mice harboring P493 tumor xenografts, BPTES treatment inhibited tumor cell growth; however, P493 xenografts expressing a BPTES-resistant GLS mutant (GLS-K325A) or overexpressing GLS were not affected by BPTES treatment. Moreover, a customized Vivo-Morpholino that targets human GLS mRNA markedly inhibited P493 xenograft growth without affecting mouse Gls expression. Conversely, a Vivo-Morpholino directed at mouse Gls had no antitumor activity in vivo. Collectively, our studies demonstrate that GLS is required for tumorigenesis and support small molecule and genetic inhibition of GLS as potential approaches for targeting the tumor cell-autonomous dependence on GLS for cancer therapy.

Blocking lactate export by inhibiting the Myc target MCT1 Disables glycolysis and glutathione synthesis.

Myc oncoproteins induce genes driving aerobic glycolysis, including lactate dehydrogenase-A that generates lactate. Here, we report that Myc controls transcription of the lactate transporter SLC16A1/MCT1 and that elevated MCT1 levels are manifest in premalignant and neoplastic Eµ-Myc transgenic B cells and in human malignancies with MYC or MYCN involvement. Notably, disrupting MCT1 function leads to an accumulation of intracellular lactate that rapidly disables tumor cell growth and glycolysis, provoking marked alterations in glycolytic intermediates, reductions in glucose transport, and in levels of ATP, NADPH, and ultimately, glutathione (GSH). Reductions in GSH then lead to increases in hydrogen peroxide, mitochondrial damage, and ultimately, cell death. Finally, forcing glycolysis by metformin treatment augments this response and the efficacy of MCT1 inhibitors, suggesting an attractive combination therapy for MYC/MCT1-expressing malignancies.

Mobile interspersed repeats are major structural variants in the human genome.

Characterizing structural variants in the human genome is of great importance, but a genome wide analysis to detect interspersed repeats has not been done. Thus, the degree to which mobile DNAs contribute to genetic diversity, heritable disease, and oncogenesis remains speculative. We perform transposon insertion profiling by microarray (TIP-chip) to map human L1(Ta) retrotransposons (LINE-1 s) genome-wide. This identified numerous novel human L1(Ta) insertional polymorphisms with highly variant allelic frequencies. We also explored TIP-chip's usefulness to identify candidate alleles associated with different phenotypes in clinical cohorts. Our data suggest that the occurrence of new insertions is twice as high as previously estimated, and that these repeats are under-recognized as sources of human genomic and phenotypic diversity. We have just begun to probe the universe of human L1(Ta) polymorphisms, and as TIP-chip is applied to other insertions such as Alu SINEs, it will expand the catalog of genomic variants even further.

Isolation and characterization of microsatellite markers in the striped hamster (Cricetulus barabensis).

A total of 14 polymorphic microsatellite markers were isolated and characterized from the striped hamster, Cricetulus barabensis, a widespread rodent pest in northern China. Two to six alleles per locus were detected in 90 individuals from three locations in Shandong Province, China. The observed and expected heterozygosities ranged from 0.21 to 0.78 and from 0.30 to 0.80, respectively. These microsatellite markers provide new tools for investigating the population structure of this species.