The Prognostic Significance of Tryptophanyl-tRNA Synthetase in Colorectal Cancer
ABSTRACT Tryptophanyl-tRNA synthetase (TrpRS) is an aminoacyl-tRNA synthetase involved in protein synthesis and regulation of RNA transcription and translation and is an inhibitor of angiogenesis. TrpRS has been shown to be differentially expressed in colorectal cancer (CRC) and has thus been identified as a potential prognostic marker. The aim of this study was to analyze the correlation of TrpRS to the prognosis of patients diagnosed and treated for CRC within a defined population.
With a polyclonal, monospecific IgG antibody, TrpRS expression was assessed by immunohistochemistry on tissue microarrays with tumors from a population-based CRC cohort (n = 320). Staining intensity and fraction of positive tumor cells were recorded. A Cox multivariate model including TrpRS expression, carcinoembryonic antigen, age, stage, tumor differentiation, and lymphatic and vascular vessel invasion was used to calculate the hazard ratio and 95% confidence interval (95% CI) for time to recurrence, disease-free survival, and overall survival.
Low expression of TrpRS correlated to increased risk for lymph node metastasis (P = 0.025) and a more advanced tumor stage (P = 0.001). Patients with tumors and increased levels of TrpRS expression had better survival than patients with low expression levels. Multivariate analyses revealed significantly better disease-free survival (relative risk, 0.59; 95% CI, 0.38-0.95) for patients with high expression than for patients with low expression of TrpRS. For colon cancer patients, a reduced risk for recurrence was seen in patients with increased TrpRS expression (relative risk, 0.23; 95% CI, 0.07-0.80).
Low expression of TrpRS in tumor tissue correlates with increased risk for recurrence and worse survival in patients with CRC. This can be related to its antiangiogenic properties and could aid in the future selection of new drugs in the treatment of CRC.
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ABSTRACT: Tryptophanyl-tRNA synthetase (TrpRS) expression alters in colorectal (CRC), pancreatic (PC), and cervical (CC) cancers. Here, phosphorylation of unfolded TrpRS and its fragments is stimulated by human cancer sera (CS; n = 13) and serum of rabbit tumor induced by Rous sarcoma virus, unaffected by donor sera (NS; 11/15) and abolished by alkaline phosphatase. At 20 years of follow-up, serum-inducible TrpRS phosphorylation found years before healthy donors (3/15) diagnosed with PC, CRC, or leukemia. I have examined a specificity of serum-inducible TrpRS phosphorylation and found, surprisingly, that serine phosphorylation of unfolded TrpRS is stimulated by anti-TrpRS rabbit antisera but is unaffected by rabbit nonimmune sera and antisera to other antigens. Anti-TrpRS immunoglobulin G (IgG) inhibits phosphorylation of full-length TrpRS and stimulates phosphorylation of its 20-kDa fragment. Phosphorylation of this fragment is stimulated also by CS but not NS. 2-Mercaptoethanol and cyclic AMP exerted synergistic inhibitory effect on TrpRS phosphorylation. Anti-TrpRS sera and casein act as chaperones increasing TrpRS phosphorylation through refolding. Histone-specific protein kinase activity in CS (n = 44) and anti-TrpRS sera was lower than that in NS (n = 11), rabbit nonimmune sera and antisera to other antigens. TrpRS inhibitors, tryptamine, and tryptophanol stimulate in vivo accumulation of enzymatically inactive, nonphosphorylated, aggregated and anti-TrpRS IgG refoldable TrpRS. Phosphorylation of postsurgical tissues (n = 18) reveals TrpRS in ovarian cancer (OVC) and CC but not in normal placenta and liver. In OVC, TrpRS phosphorylation increase correlates with elevated tryptophan-dependent ATP-inorganic pyrophosphate exchange. Although not inducing cancer, TrpRS triggers signaling concomitant with cancer.Translational oncology 12/2011; 4(6):377-89. DOI:10.1593/tlo.11220 · 3.40 Impact Factor
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ABSTRACT: Preoperative chemoradiotherapy (CRT) is the treatment of choice for rectal cancer (RC), but half of the patients do not respond, suffer unnecessary toxicities, and surgery delays. We aimed to develop a model that could predict a clinically meaningful response to CRT by using formalin-fixed paraffin-embedded (FFPE) biopsies. We first carried out an exploratory screening of candidate genes by using SAGE technology to evaluate dynamic changes in the RC transcriptome in selected refractory patients before and after CRT. Next, 53 genes (24 from SAGE and 29 from the literature) were analyzed by qPCR arrays in FFPE initial biopsies from 94 stage II/III RC patients who were preoperatively treated with CRT. Tumor response was defined by using Dworak's tumor regression grade (2-3-4 vs. 0-1). Multivariate Cox methods and stepwise algorithms were applied to generate an optimized predictor of response and outcome. In the training cohort (57 patients), a 13-gene signature predicted tumor response with 86% accuracy, 87% sensitivity, and 82% specificity. In a testing cohort (37 patients), the model correctly classified 6 of 7 nonresponders, with an overall accuracy of 76%. A signature-based score identified patients with a higher risk of relapse in univariate (3-year disease-free survival 64% vs. 90%, P = 0.001) and multivariate analysis (HR = 4.35 95% CI: 1.2-15.75, P = 0.02), in which it remained the only statistically significant prognostic factor. A basal 13-gene signature efficiently predicted CRT response and outcome. Multicentric validation by the GEMCAD collaborative group is currently ongoing. If confirmed, the predictor could be used to improve patient selection in RC studies.Clinical Cancer Research 04/2011; 17(12):4145-54. DOI:10.1158/1078-0432.CCR-10-2257 · 8.19 Impact Factor
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ABSTRACT: Tryptophanyl-tRNA synthetase (TrpRS) catalyzes tryptophanyl-tRNAtrp formation. At concentrations exceeding tryptophan, tryptamine inhibits TrpRS. This leads in tryptophanyl-tRNA deficiency and synthesis of aberrant proteins. Tryptamine presents in food and crosses blood-brain barrier. The purpose of this study is to test the hypothesis that tryptamine-induced changes in cell and animal models correlate with Alzheimer's disease (AD) manifestations. Tryptamine prevented growth of human neuroblastoma. Epithelioids recovered growth in tryptamine-free medium, while neuroblasts died. Tryptamine induced epithelioid differentiation forming synaptic vesicles, neuritic contacts, and TrpRS+ axons in stable sublines. A fraction of epithelioids was adhered to satellite cells via trypsin-resistant interdigitating junctions. Tryptamine stimulated satellite division and differentiation into neurons, transitional cell variants and neuroblasts able to repopulate. Both tryptamine-inhibited and hypoxia-downregulated TrpRS translocates into cytoplasmic extensions. TrpRS is secreted into extracellular space as a free protein or within vesicles extended from cytoplasm and then pinched-off from plasma membrane of tryptamine-treated cells. Extracellular vesicles fuse in congophilic TrpRS+ plaques in tryptamine-treated culture and AD brain. TrpRS prominent immunoreactivity is associated with plasma and vesicle membranes of satellites and AD brain degenerated neurons. Tryptamine-modified mouse brain expresses amyloid and abnormal filaments in extracellular and neuronal plasma membrane vesicles. Radiolabeled tryptamine, tryptophan and serotonin uptake was 10-fold lower in tryptamine-resistant compared to tryptamine-sensitive cells. In both variants, tryptamine uptake exceeded tryptophan uptake within 2-h assuring TrpRS inhibition. Here, tryptophanyl-tRNAtrp deficiency implicates in both neurite growth and termination/collapse. Neurite growth termination prompts TrpRS+ vesicularization. TrpRS+ vesicles contribute in neuronal fragmentation and fibrillar-vesicular congophilic plaques in AD brain.Journal of Alzheimer's disease: JAD 05/2011; 26(2):263-98. DOI:10.3233/JAD-2011-110176 · 3.61 Impact Factor