AHNAK2 Urinary Protein Expression as Potential Biomarker for Bladder Cancer Detection: A Pilot Study

Abstract

Objective: This study aimed to measure the AHNAK2 urinary levels in bladder cancer patients. Material and methods: This prospective case–control study enrolled 67 participants between January and March 2019 and were categorized into bladder cancer group (n = 37), with histologically proven bladder cancer, and control group (n = 30), with histologically verified benign lesions or with no bladder cancer indication during follow-up. Urine samples of 15 mL were collected in the mid-morning before cystoscopy/surgery and an enzyme-linked immunosorbent assay was performed as per the manufacturer’s protocol. Bladder malignancies were classified according to the World Health Organization Tumor Classification. Group’s associations were evaluated with the Student t -test, Spearman’s rank correlation, and Mann–Whitney U test, while receiver operating curve was plotted for assessing the test’s performance. Results: Mean age of the bladder cancer group was 66.41 years (standard deviation = 10.04, range = 43-82 years) and the control group was 59.67 years (standard deviation = 10.44, range = 38-77 years). All bladder cancers were of the urothelial histotype, with the following pT distribution: pTa/papillary urothelial neoplasm of low malignant potential (n = 19; 28.4%), Primary tumor (pT) in situ (n = 4; 6%), pT1 (n = 7; 10.4%), and pT≥2 (n = 7; 10.48%). Mean AHNAK2 levels were higher in bladder cancer patients 49.08 pg/mL (standard deviation = 114.91) compared to controls 5.28 pg/mL (standard deviation = 6.65), P < .05). Significant differences were noted between non-invasive bladder cancer (n = 23; mean = 7.14 pg/mL; standard deviation = 7.26) and invasive bladder cancer (n = 14; mean = 117.99 pg/mL; standard deviation = 168.08) and between non-muscle invasive bladder cancer (mean = 23.19 pg/mL; standard deviation = 66.93) and muscle-invasive bladder cancer (mean = 160.05 pg/mL; standard deviation = 199.65) ( P < .001). The result of the assays was given as follows: sensitivity: 64.19%, specificity: 66.67%, positive predictive value: 22.07%, negative predictive value: 92.37%, area under curve: 0.695, and 95% CI: 0.57-0.82. Conclusion: AHNAK2 protein could be used as bladder cancer surveillance biomarker. The inclusion of AHNAK2 levels in stratification nomograms might reduce the number of unnecessary cystoscopies.

AHNAKs roles in physiology and malignant tumors

“…collected urine samples from 67 cancer patients with bladder occupancy (bladder cancer group N=37, benign bladder tumors N=30) and found that the mean urinary AHNAK2 protein level was almost 10 times higher in bladder cancer patients than that in controls (49.08 pg/mL vs. 5.28 pg/mL) and that AHNAK2 expression level in invasive bladder cancer was significantly higher than that in non-invasive bladder cancer (117.99 pg/mL vs. 7.14 pg/mL). Similarly, AHNAK2 level was significantly higher in muscle-invasive bladder cancer than that in non-muscle-invasive bladder cancer (160.05 pg/mL vs. 23.19 pg/mL) ( 102 ). A large sample analysis using the TCGA and GEO databases has been reported to confirm that AHNAK2 is overexpressed in bladder cancer and is associated with poorer overall survival ( 103 ).…”