Exposure of the telomere overhang acts as a DNA damage signal, and exogenous administration of an 11-base oligonucleotide homologous to the 3′-telomere overhang sequence (T-oligo) mimics the effects of overhang exposure by inducing senescence and cell death in non-small cell lung cancer (NSCLC) cells, but not in normal bronchial epithelial cells. T-oligo-induced decrease in cellular proliferation in NSCLC is likely directed through both p53 and its homolog, p73, with subsequent induction of senescence and expression of senescence-associated proteins, p21, p33ING, and p27Kip1 both in vivo and in vitro. Additionally, T-oligo decreases tumor size and inhibits angiogenesis through decreased VEGF signaling and increased TSP-1 expression.

T-oligo, an 11-base oligonucleotide homologous to the 3'-telomeric overhang, is a novel, potent therapeutic modality in melanoma and multiple other tumor types. T-oligo is proposed to function in a manner similar to experimental disruption of the telomere overhang and induces DNA damage responses including apoptosis, differentiation and senescence. However, important components involved in T-oligo induced responses are not defined, particularly the role of p53, TRF1 and TRF2 in mediating the T-oligo induced responses. In MU, PM-WK, and MM-MC melanoma cells, exposure to T-oligo upregulates p53 expression and phosphorylation, resulting in cellular differentiation and activation of a caspase-mediated apoptotic cascade. However, siRNA-mediated knockdown of p53 completely blocks T-oligo induced differentiation and significantly decreases apoptosis, suggesting that p53 is an important mediator of T-oligo induced responses. In addition, we characterized the roles of telomere binding proteins, TRF1, TRF2, and tankyrase-1, in T-oligo induced damage responses. We demonstrate that tankyrase-1 activity is required for initiation of T-oligo induced damage responses including p53 phosphorylation and reduction of cellular proliferation. These results highlight TRF1, TRF2, tankyrase-1 and p53 as important elements in T-oligo mediated responses and suggest new avenues for research into T-oligo's mechanism of action.

Recent studies suggest that FTO variants strongly correlate with obesity and mainly influence energy intake with little effect on the basal metabolic rate. We suggest that FTO influences eating behavior by modulating intracellular energy levels and downstream signaling mechanisms which control energy intake and metabolism. Since FTO plays a particularly important role in adipocytes and in hypothalamic neurons, SH-SY5Y neuronal cells and 3T3-L1 adipocytes were used to understand how siRNA mediated knockdown of FTO expression alters cellular energy homeostasis. Cellular energy status was evaluated by measuring ATP levels using a luminescence assay and uptake of fluorescent glucose. FTO siRNA in SH-SY5Y cells mediated mRNA knockdown (−82%), increased ATP concentrations by up to 46% (P = 0.013) compared to controls, and decreased phosphorylation of AMPk and Akt in SH-SY5Y by −52% and −46% respectively as seen by immunoblotting. In contrast, FTO siRNA in 3T3-L1 cells decreased ATP concentration by −93% (p<0.0005), and increased AMPk and Akt phosphorylation by 204% and 70%, respectively suggesting that FTO mediates control of energy levels in a cell-type specific manner. Furthermore, glucose uptake was decreased in both SH-SY5Y (−51% p = 0.015) and 3T3-L1 cells (−30%, p = 0.0002). We also show that FTO knockdown decreases NPY mRNA expression in SH-SY5Y cells (−21%) through upregulation of pSTAT3 (118%). These results provide important evidence that FTO-variant linked obesity may be associated with altered metabolic functions through activation of downstream metabolic mediators including AMPk.

BackgroundExperimental disruption of the telomere overhang induces a potent DNA damage response and is the target of newly emerging cancer therapeutics. Introduction of T-oligo, an eleven-base oligonucleotide homologous to the 3′-telomeric overhang, mimics telomere disruption and induces DNA damage responses through activation of p53, p73, p95/Nbs1, E2F1, pRb, and other DNA damage response proteins. ATM (ataxia telangiectasia mutated) was once thought to be the primary driver of T-oligo-induced DNA damage responses; however, recent experiments have highlighted other key proteins that may also play a significant role.MethodsTo identify proteins associated with T-oligo, MM-AN cells were treated with biotinylated T-oligo or complementary oligonucleotide, cell lysates were run on SDS-PAGE (sodium dodecyl sulfate polyacrylamide gel electrophoresis), and the protein bands observed after treatment of cells with T-oligo or complementary oligonucleotide were analyzed using mass spectrometry. To study the effect of T-oligo on expression of hnRNP C1/C2 (heterogeneous nuclear ribonucleoprotein C1 and C2) and purine-rich element binding proteins (Pur proteins), cells were treated with T-oligo, and immunoblotting experiments were performed. To determine their role in senescence, cells were treated with shRNA (short hairpin ribonucleic acid) against these proteins, and senescence was studied using the senescence associated beta-galactosidase assay.ResultsUsing mass spectrometry, RNA-binding hnRNP C1/C2 and DNA-binding Pur proteins were found to associate with T-oligo. hnRNP C1/C2 exhibited increased expression (3.6–12.0-fold) in non-small-cell lung cancer (NSCLC) and in melanoma cells (4.5–5.2-fold), and Pur proteins exhibited increased expression of 2.2-fold in NSCLC and 2.0-fold in melanoma cells after T-oligo treatment. Experimental knockdown of hnRNP C1/C2 and Pur-beta completely abrogated T-oligo induced senescence in both MU melanoma and H358 NSCLC cells. Additionally, knockdown of Pur-beta prevented T-oligo-induced phosphorylation of p53, hypophosphorylation of pRb, and upregulation of E2F1, p21, and p53.ConclusionThese novel findings highlight proteins essential to T-oligo’s anticancer effects that may be of interest in telomere biology and cancer therapeutics.

Pediatric endoscopy has revolutionized the way we diagnose and treat gastrointestinal disorders in children. Technological advances in computer processing and imaging continue to affect endoscopic equipment and advance diagnostic tools for pediatric endoscopy. Although commonly used by adult gastroenterologists, modalities, such as endomicroscopy, image-enhanced endoscopy, and impedance planimetry, are not routinely used in pediatric gastroenterology. This state-of-the-art review describes advances in diagnostic modalities, including image-enhanced endoscopy, confocal laser endomicroscopy, optical coherence tomography, endo functional luminal imaging probes, wireless motility/pH capsule, wireless colon capsule endoscopy, endoscopic ultrasound, and discusses the basic principles of each technology, including adult indications and pediatric applications, safety cost, and training data.

No abstract

Telomeres are tandem repeats of the DNA sequence TTAGGG. The 3’ end of each telomere consists of a single stranded overhang that is normally concealed in a loop structure at the chromosome ends. We postulate that exposure of this sequence upon telomere disruption induces anticancer responses such as apoptosis and senescence. An 11-base oligonucleotide homologous to the telomere 3’ overhang sequence, (T-oligo) is thought to mimic exposure of the telomere overhang. T-oligo decreased NSCLC viability in six cell lines by 40-50% and induced a 3 fold increase in apoptosis and 10 fold increase in senescence. T-oligo did not effect cell proliferation or induce apoptosis or senescence in normal bronchial epithelial cells. To investigate proteins that bind to T-oligo which could induce apoptosis and senescence, cancer cells were treated with biotinylated T-oligo or complementary oligo, and T-oligo associated proteins were immunoprecipitated. Further analysis of unique protein bands after gel electrophoresis and mass spectrometry indicated that proteins such as hnRNP C, Purβ, and Msi-1 which are known to interact with the telomere and modulate p53 and pRb were bound to T-oligo. We hypothesize that T-oligo modulates hnRNP C, Purβ, and Msi-1 and induces various anticancer effects. We found in NSCLC cell lines H358 and SW1573 that hnRNP C was upregulated by T-oligo at 18 hrs and Purβ was found to be upregulated at 18 hrs in H358. Similar results were observed in two melanoma cells lines, MU and MM-AN. T-oligo upregulated hnRNP C at 18 hrs and 6 hrs in MM-AN and MU melanoma cells respectively. Additionally, Purβ and Msi-1 were upregulated at 24 and 48 hrs in MM-AN cells treated with T-oligo. To investigate hnRNP Cs involvement in senescence in H358 cells, hnRNP C was downregulated using shRNA in a lentiviral vector. It was found that 7 days after T-oligo treatment, 70% of the cells were positive for senescence associated β-galactosidase (β-gal) compared to 5% positive cells after control shRNA treatment. However, in cells treated with T-oligo after downregulation of hnRNP C only 8% of cells were positive for β-gal indicating that hnRNP C played an important role in mediating senescence. To test the ability of T-oligo as a therapeutic drug, subcutaneous tumors in nude mice were given daily intratumoral injections of 60 nmoles of T-oligo or a complementary oligonucleotide for 6 weeks. SW1573 and H358 tumors treated with T-oligo exhibited a 5.6 and 4.3 fold reduction in tumor size respectively. When tumor sections were further examined for senescence using β-gal, both H358 and SW1573 exhibited strong staining for senescence compared to minimal staining in controls. These results indicate that T-oligo not only reduced tumor size, but also induced senescence in tumor cells. These findings suggest that T-oligo may be a novel molecularly targeted therapy and its associated proteins may be novel cancer targets. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 1592.