Tracking profiles of genomic instability in spontaneous transformation and tumorigenesis

The dominant paradigm for cancer research focuses on the identification of specific genes for cancer causation and for the discovery of therapeutic targets. Alternatively, the current data emphasize the significance of karyotype heterogeneity in cancer progression over specific gene-based causes of cancer. Variability of a magnitude significant to shift cell populations from homogeneous diploid cells to a mosaic of structural and numerical chromosome alterations reflects the characteristic low-fidelity genome transfer of cancer cell populations. This transition marks the departure from micro-evolutionary gene-level change to macro-evolutionary change that facilitates the generation of many unique karyotypes within a cell population. Considering cancer cell populations to be complex-adaptive systems, multi-level analyses were performed longitudinally including whole genome microarray, population karyotype analysis, and determination of cell phenotype. As heterogeneity in ovarian cancer at each of these levels is linked to low survival, metastasis, and resistance to chemotherapy, a syngeinc model of spontaneous ovarian cancer development was employed. The significant findings of the current study are, 1) Genomic instability was apparent from the earliest stages of study, 2) Karyotypic heterogeneity was widespread, showed a pattern of expansion over time and preceded the acquisition of the transformed phenotype 3) a major karyotypic shift occurred between transformed cells in vivo and tumors formed in vitro, documenting the formation of a new system induced by environmental change 4) Chromosome copy number has greater impact on gene expression in early-stage cell populations, where karyotypes are beginning to depart from the diploid genome. A genome-centered paradigm for transformation is emphasized through the discovery of early large-scale increases in karyotype heterogeneity. This occurred well before the appearance of the transformed phenotype, arose much faster in Brca1 conditionally inactivated cells, was linked to the largest shift in gene expression, and was linked to the transition from in vitro to in vivo survival facilitating tumorigenesis. These data demonstrate the significance, methodologies and rationale for quantifying karyotype heterogeneity in transformation, tumorigenesis, and clinical cancers. Together, these findings support of a genome-centered evolutionary framework for cancer progression that emphasizes cell-to-cell genomic variability as the basis for macro-evolutionary selection and rapid phenotypic switching in response to new environments

On Disruption

On Disruptio

Modelling neoplastic progression in epithelial ovarian cancer

A national screening programme could significantly reduce mortality from epithelial ovarian cancer (EOC). The biological events that occur in the early stages of development of EOCs remain poorly understood, thus hindering the discovery of biomarkers of early disease. This thesis describes the development of a three-dimensional heterotypic genetic model of neoplastic transformation of normal ovarian surface epithelial (NOSE) cells. hTERT, C-MYC, KRAS and BRAF are genes that are commonly mutated or overexpressed in EOCs. Ectopic expression of hTERT increased in vitro lifespan of NOSE cells without inducing neoplastic transformation. Subsequent overexpression of CMYC +/- KRASG12V /BRAFV 600E in immortalised NOSE (IOSE) cells induced a significant increase in anchorage-independent growth and invasive ability. In in vitro assays and gene expression microarrays, phenotypic and molecular heterogeneity was associated with differential oncogene expression. Physiological and biological features of NOSE cells grown in 3D more closely resembled characteristics of NOSE cells in vivo than when grown by classical two-dimensional (2D) approaches. 3D models of oncogene-expressing clones revealed characteristics of malignant cells in vivo that could not be detected in 2D monolayer cultures. Gene expression microarrrays profiles of ~25,000 genes were generated to identify novel genes that are altered synergistically with the oncogenes that were introduced. A panel of genes has been identified that provides novel candidates for detecting ovarian carcinomas at the earliest, most treatable, stages of disease. Finally, a role for ageing fibroblasts in the initiation of EOC development was explored. In 2D and 3D in vitro co-culture assays, pre-senescent and senescent ovarian fibroblasts differentially affected proliferation, anchorage-independent growth, migration and invasion of IOSECMYC cell lines but not of IOSE cells. These data provide in vitro evidence that the ageing microenvironment can promote transformation of ovarian epithelial cells, and that this is conditional upon mutation in the OSE

Rheumatic fever: New ideas in diagnosis and management

Rheumatic heart disease remains a major cause of disability and death in developing countries. Careful re-analysis of mid-20th century data as well as the juxtaposition of well-funded research units and populations at risk have generated information that resulted in radical departures from standard approaches to the prevention, clinical recognition and treatment of acute rheumatic fever. As a result, rheumatic heart disease may be eliminated in the future

Development and validation of a new glaucoma screening test using temporally modulated flicker

Purpose Describing the psychometric characteristics and diagnostic accuracy of the Accelerator 4‐Alternative Forced‐Choice Flicker Test prototype (A4FTp) for detecting chronic open angle glaucoma (COAG). Methods A4FTp measures temporally‐modulated flicker thresholds in regions of the visual field with high susceptibility to glaucomatous loss. We initially evaluated its psychometric properties on 20 normals (aged 33.8 ± 8.5 years) who were tested multiple times over a period of 3 months. All subjects underwent four repetitions for shorter (T8) and longer (T12) staircase termination criteria, to determine the most suitable threshold criterion. Four randomly selected subjects underwent a total of 10 repetitions to study test‐retest repeatability and learning effects. To determine its diagnostic accuracy, one eye of 40 participants with COAG and 38 normal controls were tested with the A4FTp in comparison with the Frequency Doubling Technology (FDT; C20‐5 programme) and iVue Spectral Domain Optical Coherence Tomography (SD‐OCT). Tests were conducted in a random order with results masked to the clinician conducting the reference ophthalmic examination. The accuracy of each test was determined by analysis of the area under the receiver operator characteristic curve (AUROC). Results A4FTp flicker thresholds were stable, with standard deviations of only 0.52 decilog (dL) for T8, increasing to 1.32 dL for T12, and no significant flicker sensitivity threshold improvement over the 10 repeat runs. T8 was superior to T12 on several other measures, so it was used for the remaining comparisons. In terms of diagnostic accuracy, the mean AUROC for the three tests were A4FTp [T8 criterion; 0.82, 95% confidence interval (0.73–0.92)]; SD‐OCT [any RNFL parameter p < 1% level; 0.90 (0.83–0.97)]; and FDT [one or more locations missed at p < 5% level; 0.91 (0.82–0.96)]. There was no statistical difference in AUROC between A4FTp and SD‐OCT (p = 0.18) or FDT (p = 0.12). The A4FTp test duration averaged just over 2 min per eye, taking approximately one‐third of the time for completion of the HFA SITA 24‐2 algorithm (conducted as part of the reference examination) and twice the time for the suprathreshold FDT. Conclusion Test accuracy for the A4FTp was comparable to those of the FDT and SD‐OCT for the detection of COAG. Time taken to complete the A4FTp was relatively short and initial results are promising. With further refinement, the A4FTp could have a future role in glaucoma detection

Initial experience in self-monitoring of intraocular pressure.

Background/aims: Diurnal variation in intraocular pressure (IOP) is a routine assessment in glaucoma management. Providing patients the opportunity to perform self-tonometry might empower them and free hospital resource. We previously demonstrated that 74% of patients can use the Icare® HOME tonometer. This study further explores Icare® HOME patient self-monitoring. Methods: Patients were trained by standard protocol to use the Icare® HOME rebound tonometer. Patient self-tonometry was compared to Goldmann applanation tonometry (GAT) over one clinical day. Following this, each patient was instructed to undertake further data collection that evening and over the subsequent two days. Results: Eighteen patients (35 eyes) participated. Good agreement was demonstrated between GAT and Icare® HOME for IOPs up to 15 mm Hg. Above this IOP the Icare® tended to over-read, largely explained by 2 patients with corneal thickness >600 um. The mean peak IOP during ‘clinic hours’ phasing was 16.7 mm Hg and 18.5 mm Hg (p = 0.24) over three days. An average range of 5.0, 7.0 and 9.8 mm Hg was shown during single day clinic, single day home and three day home phasing respectively (p =<0.001). The range of IOP was lower in eyes with prior trabeculectomy (6.1 mm Hg vs 12.2 mm Hg). All patients undertook one reading in the early morning at home with an average of 4.8 readings during, and 3.1 readings after office hours. Conclusions: This small study shows that self-tonometry is feasible. The findings from home phasing demonstrated higher peak and trough IOPs, providing additional clinical information. Home phasing is a viable alternative. The cost-effectiveness of this approach has yet to be addressed

Controversies in the use of nutritional supplements in ophthalmology

Nutritional supplements are widely taken by the general population and several of these products are marketed specifically to improve eye health. The aim of this review is to summarise the evidence for the benefit of supplementation with antioxidant vitamins and other micronutrients for three of the most common eye diseases of the elderly: age-related macular degeneration (AMD), cataract and dry eye syndrome (DES). Although the potential importance of diet and nutrition in these conditions is strongly supported by data from observational studies, evidence from randomised controlled trials (RCTs) on the benefit of nutritional supplementation is generally lacking. However, there is high quality evidence to support the use of an Age-Related Eye-Disease Study (AREDS) supplement containing antioxidants ( -carotene, vitamin C and vitamin E) and zinc to slow progression in those at moderate to high risk of developing advanced AMD. Recent data from the AREDS2 trial provided data to suggest that -carotene could be replaced with lutein and zeaxanthin on the based on improved safety without compromising efficacy. Although there is currently insufficient evidence to recommend the routine use of any of the commercially available supplements in cataract and DES, given the public health importance of these conditions further research into the benefit of dietary modification or nutritional supplementation should be a priority