Investigation of IMPDH2 overexpression in renal cell carcinoma (RCC) & its association with oncologic outcomes

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Background: Approximately 40% of locoregional RCC patients relapse after nephrectomy leading to lower 5 year survival rates of 53% (stage III) & 8% (metastatic). No biomarkers of prognostic significance are in clinical use at this time. It is important to identify biomarkers that can better inform clinicians the nature of disease & personalize treatment. It is even better if the biomarkers are targetable with drugs. Inosine 5”-mono-phosphate dehydrogenase type II (IMPDH2), a rate limiting enzyme in the de novo guanine nucleotide biosynthesis is upregulated in many tumor types. Work by Sasaki laboratory showed increased GTP synthesis by IMPDH2 upregulation is important for cell growth, metastasis & cell maintenance in Gliobastoma Multiforme cell lines. Hypothesis: We are investigating the feasibility of using IMPDH2 expression in RCC as a diagnostic & prognostic biomarker. Methods: 45 cases of clear cell RCC (all stages) were identified by chart review. Slides reviewed to identify blocks with carcinoma, normal tissue & interface. Tissue microarray (TMA) was constructed using the fully automated TMA Master. TMA sectioned and stained with H &E & IMPDH2 antibody. Staining interpretation: TMA stained with IMPDH2 were reviewed based on IRS scoring system (PP x SI) - percentage positive(PP) cells (Negative-0, ≤ 10% -1, ≥ 11%- ≤ 50%- 2, ≥ 51%-≤ 80% -3, and ≥ 81%-4) & staining intensity (SI) (Negative-0, Weak-1, Moderate-2, and Strong-3). The scoring pathologist was blinded to the clinical data & outcomes of patients. Results: Preliminary results show IMPDH2 is overexpressed in RCC and tumor-normal interface compared to normal kidney. Further analyses are ongoing if IMPDH2 overexpression correlates with pertinent clinical & pathological variables including TNM stage, histologic grade (Fuhrman Grade) & oncologic outcomes including overall survival (OS) & risk of relapse. Conclusions: In the era of Sunitinib being approved as an adjuvant therapy (but not widely used due to lack of OS data), the above data will be important to verify if IMPDH2 can be used as a clinically useful test & may give insight to future personalized & targeted treatment strategies (IMPDH2 inhibitors like mycophenolate) for RCC.

Evidence for internuclear signaling in drosophila embryogenesis

BACKGROUND

Syncytial nuclei in Drosophila embryos undergo their first 13 divisions nearly synchronously. In the last several cell cycles, these division events travel across the anterior-posterior axis of the syncytial blastoderm in a wave. The phenomenon is well documented but the underlying mechanisms are not yet understood.

RESULTS

We study timing and positional data obtained from in vivo imaging of Drosophila embryos. We determine the statistical properties of the distribution of division times within and across generations with the null hypothesis that timing of division events is an independent random variable for each nucleus. We also compare timing data with a model of Drosophila cell cycle regulation that does not include internuclear signaling, and to a universal model of phase-dependent signaling to determine the probable form of internuclear signaling in the syncytial embryo.

CONCLUSIONS

The statistical variance of division times is lower than one would expect from uncoordinated activity. In fact, the variance decreases between the 10th and 11th divisions, which demonstrates a contribution of internuclear signaling to the observed synchrony and division waves. Our comparison with a coupled oscillator model leads us to conclude that internuclear signaling must be of Response/Signaling type with a positive impulse.

Female oxytocin gene-knockout mice, in a semi-natural environment, display exaggerated aggressive behavior

Compared to results from a generation of neuropharmacological work, the phenotype of mice lacking the oxytocin (OT) peptide gene was remarkably normal. An important component of the current experiments was to assay OT-knockout (OTKO) and wild-type (WT) littermate control mice living under controlled stressful conditions designed to mimic more closely the environment for which the mouse genome evolved. Furthermore, our experimental group was comprised of an all-female population, in contrast to previous studies which have focused on all-male populations. Our data indicated that aggressive behaviors initiated by OTKO during a food deprivation feeding challenge were considerably more intense and diverse than aggressive behaviors initiated by WT. From the measures of continuous social interaction in the intruder paradigm, it emerged that OTKO mice were more offensively aggressive (attacking rumps and tails) than WT. In a test of parental behaviors, OTKO mice were 100% infanticidal while WT were 16% infanticidal and 50% maternal. Finally, 'alpha females' (always OTKO) were identified in each experiment. They were the most aggressive, the first to feed and the most dominant at nesting behaviors. Semi-natural environments are excellent testing environments for elucidating behavioral differences between transgenic mice and their WT littermates which may not be ordinarily discernible. Future studies of mouse group behavior should include examining female groupings in addition to the more usual all-male groups.

In vivo measurement accuracy in vital and necrotic canals with the Endex apex locator

Currently apex locators are being used to determine working length. This study was undertaken to see what is actually being measured and if the pulp status, i.e. vital or necrotic, makes a difference in the determination. In this in vivo study, 33 teeth, both vital and necrotic, were measured by the Endex apex locator and then radiographed. After the length determination, the file was cemented to place, the tooth extracted, and then shaved back until the file and the apex were exposed. The position of the file was measured in relation to the apical foramen. Results indicate that all measurements were within a narrow range (-0.86 mm to 0.50 mm). There was no statistical difference in measurements between vital and necrotic canals.

Mammalian integral membrane receptors are homologous to facilitators and antiporters of yeast, fungi, and eubacteria

We demonstrate that three integral membrane receptors of mammals--the ecotropic retroviral leukemia receptor (ERR), the human retroviral receptor (HRR), and the T-cell early activator (Tea)--are homologous to a family of transporters specific for amino acids, polyamines, and choline (APC), which catalyze solute uniport, solute:cation symport, or solute:solute antiport in yeast, fungi, and eubacteria. Interestingly, the ERR membrane protein was recently shown to function as a cation:amino acid cotransporter. A binary sequence similarity matrix and an evolutionary tree of the 14 members of this family, illustrating their sequence similarities and divergences, were constructed. Other proteins, including the developmentally controlled GerAII spore germination protein of Bacillus subtilis and the acetylcholine receptor of Drosophila melanogaster gave sequence comparison scores of a sufficiently large magnitude to suggest (but not to establish) a common evolutionary origin with members of the APC family. We report an extended and corrected Tea cDNA sequence and show that the mammalian Tea and ERR encoding genes are differentially expressed in tissues and cell lines. Furthermore, the two mammalian cDNA sequences hybridize with other vertebrate and yeast genomic DNAs under stringent conditions. These observations support the notion that cell surface receptor proteins in mammals are transport proteins that share a common origin with transport proteins of single-celled organisms. Thus, permeases of essential metabolites may function pathologically as viral receptors.

Activated T cells express a novel gene on chromosome 8 that is closely related to the murine ecotropic retroviral receptor

A novel cDNA clone (20.5) which is differentially expressed between two closely related T-lymphoma cell clones was isolated by subtraction-enriched differential screening. SL12.4 cells, from which the cDNA was isolated, have characteristics of thymocytes at an intermediate stage in development. A sister cell clone derived from the same tumor, SL12.3, does not express this mRNA, has a distinct phenotype, and expresses fewer genes required for mature T-cell function. The cDNA sequence predicts a highly hydrophobic protein (approximately 49.5 kilodaltons) which contains seven putative membrane spanning domains. The gene was expressed on concanavalin A-activated T lymphocytes and was designated Tea (T-cell early activation gene). The Tea gene mapped to chromosome 8 and appeared to be conserved among mammalian and avian species. The Tea gene is distinct from, but bears extensive amino acid and DNA sequence similarity with, the murine ecotropic retroviral receptor which is encoded by the Rec-1 gene. Neither gene product displayed significant homology with other known transmembrane-spanning proteins. Thus, the Tea and Rec-1 genes establish a new family encoding multiple membrane-spanning proteins.

2,8-dihydroxyadenine urolithiasis: report of a case first diagnosed after renal transplant

We report a case of homozygous adenine phosphoribosyl transferase (APRT) deficiency associated with 2,8-dihydroxyadenine stones recurrent in a patient with a renal transplant. The disease was diagnosed 23 years after the initial episode of renal colic. At that time the disease was unknown. Our patient is only the second case of this disorder reported from the United States. Correct diagnosis is important because long-term maintenance with allopurinol and a low purine diet can effectively prevent stone formation and renal failure.