Identification by Proteomic Analysis of Calreticulin as a Marker for Bladder Cancer and Evaluation of the Diagnostic Accuracy of Its Detection in Urine

Abstract

Background: New methods for detection of bladder cancer are needed because cystoscopy is both invasive and expensive and urine cytology has low sensitivity. We screened proteins as tumor markers for bladder cancer by proteomic analysis of cancerous and healthy tissues and investigated the diagnostic accuracy of one such marker in urine. Methods: Three specimens of bladder cancer and healthy urothelium, respectively, were used for proteome differential display using narrow-pH-range twodimensional electrophoresis. To evaluate the presence of calreticulin (CRT) as detected by Western blotting, we obtained 22 cancerous and 10 noncancerous surgical specimens from transurethral resection or radical cystectomy. To evaluate urinary CRT, we collected 70 and 181 urine samples from patients with and without bladder cancer, respectively. Anti-CRT COOH-terminus antibody was used to detect CRT in tissue and urine. Results: Proteomic analysis revealed increased CRT (55 kDa; pI 4.3) in cancer tissue. Quantitative Western blot analysis showed that CRT was increased in cancer tissue (P ‫؍‬ 0.0003). Urinary CRT had a sensitivity of 73% (95% confidence interval, 62-83%) at a specificity of 86% (80 -91%) for bladder cancer in the samples tested. Conclusions: Proteomic analysis is useful in searching for candidate proteins as biomarkers and led to the

Bladder Cancer Associated Glycoprotein Signatures Revealed by Urinary Proteomic Profiling

“…Unfortunately, in a larger cohort of patients, the diagnostic accuracy of calreticulin in urine was vulnerable to urinary tract infections. 22 Because none of the markers described to date have sufficient sensitivity and specificity for diagnostic use, the quest for identifying additional bladder cancer biomarkers continues. Investigators have also applied gel-free methodologies to urine analysis.…”

Diagnostic potential in bladder cancer of a panel of tumor markers (calreticulin, γ‐synuclein, and catechol‐o‐methyltransferase) identified by proteomic analysis

“…Proteome differential display analysis of bladder cancer tissues and healthy urothelial mucosa from patients without neoplastic disease was used to screen proteins that are increased in cancer tissue, followed by protein identification as we have described previously. 8,17) Briefly, total protein was applied to an immobilized pH gradient gel for isoelectric focusing, then SDS-polyacrylamide gel electrophoresis (PAGE) was performed using 12.5% polyacrylamide gel. Protein spots were visualized by silver staining, and only spots that were clearly and reproducibly more intense in specimens from the cancer patients were analyzed.…”

From regulation of dying cell engulfment to development of anti-cancer therapy

“…45 In addition to these membrane-mediated mechanisms, several cellular proteins released from apoptotic cells, including p43 aminoacyl tRNA synthases 57 and a ribosomal protein dimer, mediate monocyte attraction. 50 The exposure of calreticulin on the surface of apoptotic cells, its ability to stimulate phagocytes, 13 and its possible release 58 indicate that its potential chemoattractant activity should be examined. Efficient and rapid clearance of apoptotic cells requires signals that not only attract phagocytes but also promote engulfment.…”