Matching Items (21)

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Life History, Cancer Incidence, and Cancer Mortality in Non-Human Primates

Description

Cancer rates in our nearest relatives are largely unknown. Comparison of human cancer rates with other primates should help us to understand the nature of our susceptibilities to cancer. Data

Cancer rates in our nearest relatives are largely unknown. Comparison of human cancer rates with other primates should help us to understand the nature of our susceptibilities to cancer. Data from deceased primates was gathered from 3 institutions, the Duke Lemur Center, San Diego Zoo, and Jungle Friends primate sanctuary. This data contained over 400 unique individuals across 45 species with information on cancer incidence and mortality. Cancer incidence ranged from 0-71% and cancer mortality ranged from 0-67%. We used weighted phylogenetic regressions to test for an association between life history variables (specifically body mass and lifespan) and cancer incidence as well as mortality. Cancer incidence did not correlate with both body mass and lifespan (p>.05) however, cancer mortality did (p<.05). However, it is uncertain if the variables can be used as reliable predictors of cancer, because the data come from different organizations. This analysis presents cancer incidence rates and cancer mortality rates in species where it was previously unknown, and in some primate species, is surprisingly high. Microcebus murinus(grey mouse lemur) appear to be particularly vulnerable to cancer, mostly lymphomas. Further studies will be required to determine the causes of these vulnerabilities.

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  • 2017-05

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Exploring nuclease resistance and biological stability of threose nucleic acid

Description

Nucleic acid polymers have numerous applications in both therapeutics and research to control gene expression and bind biologically relevant targets. However, due to poor biological stability their clinical applications are

Nucleic acid polymers have numerous applications in both therapeutics and research to control gene expression and bind biologically relevant targets. However, due to poor biological stability their clinical applications are limited. Chemical modifications can improve both intracellular and extracellular stability and enhance resistance to nuclease degradation. To identify a potential candidate for a highly stable synthetic nucleic acid, the biostability of α-L-threofuranosyl nucleic acid (TNA) was evaluated under simulated biological conditions. TNA contains a four-carbon sugar and is linked by 2’, 3’ phosphodiester bonds. We hypothesized that this distinct chemical structure would yield greater nuclease resistance in human serum and human liver microsomes, which were selected as biologically relevant nuclease conditions. We found that TNA oligonucleotides remained undigested for 7 days in these conditions. In addition, TNA/DNA heteropolymers and TNA/RNA oligonucleotide duplexes displayed nuclease resistance, suggesting that TNA has a protective effect over DNA and RNA. In conclusion TNA demonstrates potential as a viable synthetic nucleic acid for use in numerous clinical and therapeutic applications.

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Date Created
  • 2016-12

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Preclinical assessment of Wee1 inhibitor AZD1775 and DNA damaging agents in the chemotherapeutic treatment of esophageal adenocarcinoma with mutated TP53

Description

Background: Esophageal adenocarcinoma (EAC) is one of the only malignancies whose incidence is rising in the United States. Current multidrug treatment for EAC has considerable toxic side effects that necessitate

Background: Esophageal adenocarcinoma (EAC) is one of the only malignancies whose incidence is rising in the United States. Current multidrug treatment for EAC has considerable toxic side effects that necessitate the development of less toxic, more specific target drugs. Recent large scale genomic analysis reveals that TP53 is the most frequently inactivated gene in EAC. One of the primary functions of TP53 and its gene product, the tumor suppressor p53, is in regulation of DNA repair in response to DNA damage. Inactivation of TP53 results in loss of the G1/S cell cycle checkpoint, and dependence on the G2/M checkpoint for DNA repair. Activity of cyclin-dependent kinase 1 (CDK1) is necessary for cells to exit the G2/M checkpoint and enter mitosis. Phosphorylation of CDK1 by the wee1 kinase inhibits CDK1 in response to DNA damage, allowing cells to maintain G2 arrest and repair the damaged DNA. Active in normal cells, wee1 kinase is critical in cancer cells to promote DNA repair and cell survival in response to DNA damage, particularly from commonly used DNA damaging therapies. AZD1775 is a small molecule inhibitor of wee1 kinase, currently under investigation in clinical trials. AZD1775 differentially targets cancer cells by blocking wee1 mediated inhibition of CDK1 and consequently preventing G2/M arrest in response to DNA damage. Combination of AZD1775 with DNA damaging agents is thought to push cancer cells with damaged DNA through to mitosis and initiate apoptosis instead of G2/M arrest and DNA repair. Based upon the incidence of TP53 mutation in EAC, we hypothesize that treatment with a DNA damaging agent in combination with AZD1775 will be as effective at eliciting DNA damage and cell death as the more toxic current standard of care, which is comprised of treatment with cisplatin, docetaxel, and radiation. Methods: p53 mutant EAC cell lines were dosed with cisplatin, AZD1775, and the combination of cisplatin and AZD1775, and then assayed for viability. Nude mice were implanted with p53 mutant patient derived xenograft esophageal adenocarcinoma tumors and randomized for treatment with AZD1775 alone, cisplatin and AZD1775, radiation and AZD1775, cisplatin, docetaxel, and radiation or vehicle (control). Tumor volume was measured over the five week treatment course. Results: In vitro and in vivo assays reveal a potent synergistic effect between AZD1775 and DNA damaging agents that is as efficacious as the standard of care therapy. The difference in AZD1775 sensitivity among TP53 mutant EAC cell lines indicates that TP53 alone may not be an adequate biomarker to assess for AZD1775- mediated toxicity.

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Date Created
  • 2016-05

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Dynamic Clonal Equilibrium and Predetermined Cancer Risk in Barrett’s Oesophagus

Description

Surveillance of Barrett’s oesophagus allows us to study the evolutionary dynamics of a human neoplasm over time. Here we use multicolour fluorescence in situ hybridization on brush cytology specimens, from

Surveillance of Barrett’s oesophagus allows us to study the evolutionary dynamics of a human neoplasm over time. Here we use multicolour fluorescence in situ hybridization on brush cytology specimens, from two time points with a median interval of 37 months in 195 non-dysplastic Barrett's patients, and a third time point in a subset of 90 patients at a median interval of 36 months, to study clonal evolution at single-cell resolution. Baseline genetic diversity predicts progression and remains in a stable dynamic equilibrium over time. Clonal expansions are rare, being detected once every 36.8 patient years, and growing at an average rate of 1.58 cm[superscript 2] (95% CI: 0.09–4.06) per year, often involving the p16 locus. This suggests a lack of strong clonal selection in Barrett’s and that the malignant potential of ‘benign’ Barrett’s lesions is predetermined, with important implications for surveillance programs.

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Date Created
  • 2016-08-19

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An Ecological Measure of Immune-Cancer Colocalization as a Prognostic Factor for Breast Cancer

Description

Introduction: Abundance of immune cells has been shown to have prognostic and predictive significance in many tumor types. Beyond abundance, the spatial organization of immune cells in relation to cancer cells

Introduction: Abundance of immune cells has been shown to have prognostic and predictive significance in many tumor types. Beyond abundance, the spatial organization of immune cells in relation to cancer cells may also have significant functional and clinical implications. However there is a lack of systematic methods to quantify spatial associations between immune and cancer cells.

Methods: We applied ecological measures of species interactions to digital pathology images for investigating the spatial associations of immune and cancer cells in breast cancer. We used the Morisita-Horn similarity index, an ecological measure of community structure and predator–prey interactions, to quantify the extent to which cancer cells and immune cells colocalize in whole-tumor histology sections. We related this index to disease-specific survival of 486 women with breast cancer and validated our findings in a set of 516 patients from different hospitals.

Results: Colocalization of immune cells with cancer cells was significantly associated with a disease-specific survival benefit for all breast cancers combined. In HER2-positive subtypes, the prognostic value of immune-cancer cell colocalization was highly significant and exceeded those of known clinical variables. Furthermore, colocalization was a significant predictive factor for long-term outcome following chemotherapy and radiotherapy in HER2 and Luminal A subtypes, independent of and stronger than all known clinical variables.

Conclusions: Our study demonstrates how ecological methods applied to the tumor microenvironment using routine histology can provide reproducible, quantitative biomarkers for identifying high-risk breast cancer patients. We found that the clinical value of immune-cancer interaction patterns is highly subtype-specific but substantial and independent to known clinicopathologic variables that mostly focused on cancer itself. Our approach can be developed into computer-assisted prediction based on histology samples that are already routinely collected.

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Date Created
  • 2015-09-22

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When (distant) relatives stay too long: implications for cancer medicine

Description

Whole-genome analyses of human medulloblastomas show that the dominant clone at relapse is present as a rare subclone at primary diagnosis.

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Date Created
  • 2016-02-24

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Peto’s Paradox: how has evolution solved the problem of cancer prevention?

Description

The risk of developing cancer should theoretically increase with both the number of cells and the lifespan of an organism. However, gigantic animals do not get more cancer than humans,

The risk of developing cancer should theoretically increase with both the number of cells and the lifespan of an organism. However, gigantic animals do not get more cancer than humans, suggesting that super-human cancer suppression has evolved numerous times across the tree of life. This is the essence and promise of Peto’s Paradox. We discuss what is known about Peto’s Paradox and provide hints of what is yet to be discovered.

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  • 2017-07-13

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The Genomics of Cancer Resistance in Long-Lived Vesper Bats

Description

Bats (order Chiroptera) are the longest lived mammals for their size, with particularly extreme longevity evolving in the family Vespertilionidae, or vesper bats. Because of this, researchers have proposed using

Bats (order Chiroptera) are the longest lived mammals for their size, with particularly extreme longevity evolving in the family Vespertilionidae, or vesper bats. Because of this, researchers have proposed using bats to study ageing and cancer suppression. Here, we study gene duplications across mammalian genomes and show that, similar to previous findings in elephants, bats have experienced duplications of the tumor suppressor gene TP53, including five genomic copies in the genome of the little brown bat (Myotis lucifugus) and two copies in Brandt's bat (Myotis brandtii). These species can live 37 and 41 years, respectively, despite having an adult body mass of only ~7 grams. We use evolutionary genetics and next generation sequencing approaches to show that positive selection has acted on the TP53 locus across bats, and two recently duplicated TP53 gene copies in the little brown bat are both highly conserved and expressed, suggesting they are functional. We also report an extraordinary genomic copy number expansion of the tumor suppressor gene FBXO31 in the common ancestor of vesper bats which accelerated in the Myotis lineage, leading to 34\u201457 copies and the expression of 20 functional FBXO31 homologs in Brandt's bat. As FBXO31 directs the degradation of MDM2, which is a negative regulator of TP53, we suggest that increased expression of both FBXO31 and TP53 may be related to an enhanced DNA-damage response to genotoxic stress brought on by long lifespans and rapid metabolic rates in bats.

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Date Created
  • 2018-12

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A survey of cancer prevalence within birds (the clave Aves).

Description

Cancer is a disease that occurs in many and perhaps all multicellular organisms. Current research is looking at how different life history characteristics among species could influence cancer rates. Because

Cancer is a disease that occurs in many and perhaps all multicellular organisms. Current research is looking at how different life history characteristics among species could influence cancer rates. Because somatic maintenance is an important component of a species' life history, we hypothesize the same ecological forces shaping the life history of a species should also determine its cancer susceptibility. By looking at varying life histories, potential evolutionary trends could be used to explain differing cancer rates. Life history theory could be an important framework for understanding cancer vulnerabilities with different trade-offs between life history traits and cancer defenses. Birds have diverse life history strategies that could explain differences in cancer suppression. Peto's paradox is the observation that cancer rates do not typically increase with body size and longevity despite an increased number of cell divisions over the animal's lifetime that ought to be carcinogenic. Here we show how Peto’s paradox is negatively correlated for cancer within the clade, Aves. That is, larger, long-lived birds get more cancer than smaller, short-lived birds (p=0.0001; r2= 0.024). Sexual dimorphism in both plumage color and size differ among Aves species. We hypothesized that this could lead to a difference in cancer rates due to the amount of time and energy sexual dimorphism takes away from somatic maintenance. We tested for an association between a variety of life history traits and cancer, including reproductive potential, growth rate, incubation, mating systems, and sexual dimorphism in both color and size. We found male birds get less cancer than female birds (9.8% vs. 11.1%, p=0.0058).

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Date Created
  • 2019-05

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The Effect of Inbreeding and Life History Traits on the Risk of Cancer Mortality in Dogs

Description

Due to artificial selection, dogs have high levels of phenotypic diversity, yet, there appears to be low genetic diversity within individual breeds. Through their domestication from wolves, dogs have gone

Due to artificial selection, dogs have high levels of phenotypic diversity, yet, there appears to be low genetic diversity within individual breeds. Through their domestication from wolves, dogs have gone through a series of population bottlenecks, which has resulted in a reduction in genetic diversity, with a large amount of linkage disequilibrium and the persistence of deleterious mutations. This has led to an increased susceptibility to a multitude of diseases, including cancer. To study the effects of artificial selection and life history characteristics on the risk of cancer mortality, we collected cancer mortality data from four studies as well as the percent of heterozygosity, body size, lifespan and breed group for 201 dog breeds. We also collected specific types of cancer breeds were susceptible to and compared the dog cancer mortality patterns to the patterns observed in other mammals. We found a relationship between cancer mortality rate and heterozygosity, body size, lifespan as well as breed group. Higher levels of heterozygosity were also associated with longer lifespan. These results indicate larger breeds, such as Irish Water Spaniels, Flat-coated Retrievers and Bernese Mountain Dogs, are more susceptible to cancer, with lower heterozygosity and lifespan. These breeds are also more susceptible to sarcomas, as opposed to carcinomas in smaller breeds, such as Miniature Pinschers, Chihuahuas, and Pekingese. Other mammals show that larger and long-lived animals have decreased cancer mortality, however, within dog breeds, the opposite relationship is observed. These relationships could be due to the trade-off between cellular maintenance and growing fast and large, with higher expression of growth factors, such as IGF-1. This study further demonstrates the relationships between cancer mortality, heterozygosity, and life history traits and exhibits dogs as an important model organism for understanding the relationship between genetics and health.

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Date Created
  • 2017-12