The c-Met receptor tyrosine kinase inhibitor MP470 radiosensitizes glioblastoma cells

<p>Abstract</p> <p>Purpose</p> <p>Glioblastoma multiforme (GBM) is resistant to current cytotoxic therapies, in part because of enhanced DNA repair. Activation of the receptor tyrosine kinase c-Met has been shown to protect cancer cells from DNA damage. We hypothesized that inhibiting c-Met would decrease this protection and thus sensitize resistant tumor cells to the effects of radiation therapy.</p> <p>Materials and methods</p> <p>Eight human GBM cell lines were screened for radiosensitivity to the small-molecule c-Met inhibitor MP470 with colony-count assays. Double-strand (ds) DNA breaks was quantified by using antibodies to gamma H2AX. Western blotting demonstrate expression of RAD51, glycogen synthase kinase (GSK)-3β, and other proteins. A murine xenograft tumor flank model was used for <it>in vivo </it>radiosensitization studies.</p> <p>Results</p> <p>MP470 reduced c-Met phosphorylation and enhanced radiation-induced cell kill by 0.4 logs in SF767 cells. Cells pretreated with MP470 had more ds DNA damage than cells treated with radiation alone. Mechanistically, MP470 was shown to inhibit dsDNA break repair and increase apoptosis. MP470 influences various survival and DNA repair related proteins such as pAKT, RAD51 and GSK3β. <it>In vivo</it>, the addition of MP470 to radiation resulted in a tumor-growth-delay enhancement ratio of 2.9 over radiation alone and extended survival time.</p> <p>Conclusions</p> <p>GBM is a disease site where radiation is often used to address both macroscopic and microscopic disease. Despite attempts at dose escalation outcomes remain poor. MP470, a potent small-molecule tyrosine kinase inhibitor of c-Met, radiosensitized several GBM cell lines both <it>in vitro </it>and <it>in vivo</it>, and may help to improve outcomes for patients with GBM.</p

Global parameter search reveals design principles of the mammalian circadian clock

Background: Virtually all living organisms have evolved a circadian (~24 hour) clock that controls physiological and behavioural processes with exquisite precision throughout the day/night cycle. The suprachiasmatic nucleus (SCN), which generates these ~24 h rhythms in mammals, consists of several thousand neurons. Each neuron contains a gene-regulatory network generating molecular oscillations, and the individual neuron oscillations are synchronised by intercellular coupling, presumably via neurotransmitters. Although this basic mechanism is currently accepted and has been recapitulated in mathematical models, several fundamental questions about the design principles of the SCN remain little understood. For example, a remarkable property of the SCN is that the phase of the SCN rhythm resets rapidly after a 'jet lag' type experiment, i.e. when the light/ dark (LD) cycle is abruptly advanced or delayed by several hours. Results: Here, we describe an extensive parameter optimization of a previously constructed simplified model of the SCN in order to further understand its design principles. By examining the top 50 solutions from the parameter optimization, we show that the neurotransmitters' role in generating the molecular circadian rhythms is extremely important. In addition, we show that when a neurotransmitter drives the rhythm of a system of coupled damped oscillators, it exhibits very robust synchronization and is much more easily entrained to light/dark cycles. We were also able to recreate in our simulations the fast rhythm resetting seen after a 'jet lag' type experiment. Conclusion: Our work shows that a careful exploration of parameter space for even an extremely simplified model of the mammalian clock can reveal unexpected behaviours and non-trivial predictions. Our results suggest that the neurotransmitter feedback loop plays a crucial role in the robustness and phase resetting properties of the mammalian clock, even at the single neuron level

Subclinical thyroid dysfunction and cognitive decline in old age

&lt;p&gt;Background: Subclinical thyroid dysfunction has been implicated as a risk factor for cognitive decline in old age, but results are inconsistent. We investigated the association between subclinical thyroid dysfunction and cognitive decline in the PROspective Study of Pravastatin in the Elderly at Risk (PROSPER).&lt;/p&gt; &lt;p&gt;Methods: Prospective longitudinal study of men and women aged 70–82 years with pre-existing vascular disease or more than one risk factor to develop this condition (N = 5,154). Participants taking antithyroid medications, thyroid hormone supplementation and/or amiodarone were excluded. Thyroid function was measured at baseline: subclinical hyper- and hypothyroidism were defined as thyroid stimulating hormones (TSH) &#60;0.45 mU/L or &#62;4.50 mU/L respectively, with normal levels of free thyroxine (FT4). Cognitive performance was tested at baseline and at four subsequent time points during a mean follow-up of 3 years, using five neuropsychological performance tests.&lt;/p&gt; &lt;p&gt;Results: Subclinical hyperthyroidism and hypothyroidism were found in 65 and 161 participants, respectively. We found no consistent association of subclinical hyper- or hypothyroidism with altered cognitive performance compared to euthyroid participants on the individual cognitive tests. Similarly, there was no association with rate of cognitive decline during follow-up.&lt;/p&gt; &lt;p&gt;Conclusion: We found no consistent evidence that subclinical hyper- or hypothyroidism contribute to cognitive impairment or decline in old age. Although our data are not in support of treatment of subclinical thyroid dysfunction to prevent cognitive dysfunction in later life, only large randomized controlled trials can provide definitive evidence.&lt;/p&gt

Subclinical thyroid dysfunction and cognitive decline in old age

&lt;p&gt;Background: Subclinical thyroid dysfunction has been implicated as a risk factor for cognitive decline in old age, but results are inconsistent. We investigated the association between subclinical thyroid dysfunction and cognitive decline in the PROspective Study of Pravastatin in the Elderly at Risk (PROSPER).&lt;/p&gt; &lt;p&gt;Methods: Prospective longitudinal study of men and women aged 70–82 years with pre-existing vascular disease or more than one risk factor to develop this condition (N = 5,154). Participants taking antithyroid medications, thyroid hormone supplementation and/or amiodarone were excluded. Thyroid function was measured at baseline: subclinical hyper- and hypothyroidism were defined as thyroid stimulating hormones (TSH) &#60;0.45 mU/L or &#62;4.50 mU/L respectively, with normal levels of free thyroxine (FT4). Cognitive performance was tested at baseline and at four subsequent time points during a mean follow-up of 3 years, using five neuropsychological performance tests.&lt;/p&gt; &lt;p&gt;Results: Subclinical hyperthyroidism and hypothyroidism were found in 65 and 161 participants, respectively. We found no consistent association of subclinical hyper- or hypothyroidism with altered cognitive performance compared to euthyroid participants on the individual cognitive tests. Similarly, there was no association with rate of cognitive decline during follow-up.&lt;/p&gt; &lt;p&gt;Conclusion: We found no consistent evidence that subclinical hyper- or hypothyroidism contribute to cognitive impairment or decline in old age. Although our data are not in support of treatment of subclinical thyroid dysfunction to prevent cognitive dysfunction in later life, only large randomized controlled trials can provide definitive evidence.&lt;/p&gt

Memory consolidation in the cerebellar cortex

Several forms of learning, including classical conditioning of the eyeblink, depend upon the cerebellum. In examining mechanisms of eyeblink conditioning in rabbits, reversible inactivations of the control circuitry have begun to dissociate aspects of cerebellar cortical and nuclear function in memory consolidation. It was previously shown that post-training cerebellar cortical, but not nuclear, inactivations with the GABA(A) agonist muscimol prevented consolidation but these findings left open the question as to how final memory storage was partitioned across cortical and nuclear levels. Memory consolidation might be essentially cortical and directly disturbed by actions of the muscimol, or it might be nuclear, and sensitive to the raised excitability of the nuclear neurons following the loss of cortical inhibition. To resolve this question, we simultaneously inactivated cerebellar cortical lobule HVI and the anterior interpositus nucleus of rabbits during the post-training period, so protecting the nuclei from disinhibitory effects of cortical inactivation. Consolidation was impaired by these simultaneous inactivations. Because direct application of muscimol to the nuclei alone has no impact upon consolidation, we can conclude that post-training, consolidation processes and memory storage for eyeblink conditioning have critical cerebellar cortical components. The findings are consistent with a recent model that suggests the distribution of learning-related plasticity across cortical and nuclear levels is task-dependent. There can be transfer to nuclear or brainstem levels for control of high-frequency responses but learning with lower frequency response components, such as in eyeblink conditioning, remains mainly dependent upon cortical memory storage

Locked Nucleic Acid Pentamers as Universal PCR Primers for Genomic DNA Amplification

Background: Multiplexing technologies, which allow for simultaneous detection of multiple nucleic acid sequences in a single reaction, can save a lot of time, cost and labor compared to traditional single reaction detection methods. However, the multiplexing method currently used requires precise handiwork and many complicated steps, making a new, simpler technique desirable. Oligonucleotides containing locked nucleic acid residues are an attractive tool because they have strong affinities for their complementary targets, they have been used to avoid dimer formation and mismatch hybridization and to enhance efficient priming. In this study, we aimed to investigate the use of locked nucleic acid pentamers for genomic DNA amplification and multiplex genotyping. Results: We designed locked nucleic acid pentamers as universal PCR primers for genomic DNA amplification. The locked nucleic acid pentamers were able to prime amplification of the selected sequences within the investigated genomes, and the resulting products were similar in length to those obtained by restriction digest. In Real Time PCR of genomic DNA from three bacterial species, locked nucleic acid pentamers showed high priming efficiencies. Data from bias tests demonstrated that locked nucleic acid pentamers have equal affinities for each of the six genes tested from the Klebsiella pneumoniae genome. Combined with suspension array genotyping, locked nucleic acid pentamer-based PCR amplification was able to identify a total of 15 strains, including 3 species of bacteria, by gene- and species-specific probes. Among the 32 specie

The impact of paratracheal lymph node metastasis in squamous cell carcinoma of the hypopharynx

The aim of this study was to analyze the prevalence and prognostic importance of paratracheal lymph nodes in squamous cell carcinoma of the hypopharynx. A retrospective review of 64 previously untreated patients with squamous cell carcinoma (SCC) of the hypopharynx that underwent surgery was performed. Ipsilateral paratracheal lymph node metastases occurred in 22% (14 out of 64) and the mean number of paratracheal lymph nodes dissected per side was 2.3 (range 1–6). Contralateral paratracheal lymph node metastases were present in 2% (1 out of 42). Sixty-seven percent with postcricoid SCC and 22% with pyriform sinus SCC developed clinical node-positive ipsilateral paratracheal lymph node metastases, whereas 11% with posterior pharyngeal wall SCC developed paratracheal metastases. There was a significant correlation between paratracheal lymph node metastasis and cervical metastasis (p = 0.005), and the primary tumor site (postcricoid, 57.1%; pyriform sinus, 20.0%; posterior pharyngeal wall, 8.3%) (p = 0.039). Patients with no evidence of paratracheal lymph node metastasis may have a survival benefit (5-year disease-specific survival rate, 60 vs. 29%). However, this result did not reach statistical significance (p = 0.071). The patients with SCC of the postcricoid and/or pyriform sinus were at risk for ipsilateral paratracheal lymph node metastasis; furthermore, patients with paratracheal node metastasis had a high frequency of cervical metastasis and a poorer prognosis. Therefore, routine ipsilateral paratracheal node dissection is recommended during the surgical treatment of patients with SCC of the postcricoid and/or pyriform sinus with clinical node metastases

Effects of Intracoronary Alteplase on Microvascular Function in Acute Myocardial Infarction

Background—Impaired microcirculatory reperfusion worsens prognosis following acute ST‐segment–elevation myocardial infarction. In the T‐TIME (A Trial of Low‐Dose Adjunctive Alteplase During Primary PCI) trial, microvascular obstruction on cardiovascular magnetic resonance imaging did not differ with adjunctive, low‐dose, intracoronary alteplase (10 or 20 mg) versus placebo during primary percutaneous coronary intervention. We evaluated the effects of intracoronary alteplase, during primary percutaneous coronary intervention, on the index of microcirculatory resistance, coronary flow reserve, and resistive reserve ratio. Methods and Results—A prespecified physiology substudy of the T‐TIME trial. From 2016 to 2017, patients with ST‐segment–elevation myocardial infarction ≤6 hours from symptom onset were randomized in a double‐blind study to receive alteplase 20 mg, alteplase 10 mg, or placebo infused into the culprit artery postreperfusion, but prestenting. Index of microcirculatory resistance, coronary flow reserve, and resistive reserve ratio were measured after percutaneous coronary intervention. Cardiovascular magnetic resonance was performed at 2 to 7 days and 3 months. Analyses in relation to ischemic time (<2, 2–4, and ≥4 hours) were prespecified. One hundred forty‐four patients (mean age, 59±11 years; 80% male) were prospectively enrolled, representing 33% of the overall population (n=440). Overall, index of microcirculatory resistance (median, 29.5; interquartile range, 17.0–55.0), coronary flow reserve(1.4 [1.1–2.0]), and resistive reserve ratio (1.7 [1.3–2.3]) at the end of percutaneous coronary intervention did not differ between treatment groups. Interactions were observed between ischemic time and alteplase for coronary flow reserve (P=0.013), resistive reserve ratio (P=0.026), and microvascular obstruction (P=0.022), but not index of microcirculatory resistance. Conclusions—In ST‐segment–elevation myocardial infarction with ischemic time ≤6 hours, there was overall no difference in microvascular function with alteplase versus placebo

Feasibility of intensity-modulated and image-guided radiotherapy for locally advanced esophageal cancer

BACKGROUND:In this study the feasibility of intensity-modulated radiotherapy (IMRT) and tomotherapy-based image-guided radiotherapy (IGRT) for locally advanced esophageal cancer was assessed.METHODS:A retrospective study of ten patients with locally advanced esophageal cancer who underwent concurrent chemotherapy with IMRT (1) and IGRT (9) was conducted. The gross tumor volume was treated to a median dose of 70Gy (62.4-75Gy).RESULTS:At a median follow-up of 14months (1-39 months), three patients developed local failures, six patients developed distant metastases, and complications occurred in two patients (1 tracheoesophageal fistula, 1 esophageal stricture requiring repeated dilatations). No patients developed grade 3-4 pneumonitis or cardiac complications.CONCLUSIONS:IMRT and IGRT may be effective for the treatment of locally advanced esophageal cancer with acceptable complications.This item is part of the UA Faculty Publications collection. For more information this item or other items in the UA Campus Repository, contact the University of Arizona Libraries at [email protected]