Activated protein kinase C-alpha as a simple test for urothelial cancer screening.

Abstract

e16552 Background: The development of a non-invasive, highly predictive diagnostic test for urothelial cancer (UC) would greatly benefit patients. Although numerous urine-based tests have been developed, it is not widely used, except for urine cytology, due to insufficient sensitivity, negative predictive value and high cost. Previously we reported that protein kinase C-alpha (PKCα) is overexpressed or activated in several cancer tissues but not in normal tissue, and we developed an activated PKCα-specific peptide substrate (FKKQGSFAKKK; Patent No. 5476559). The purpose of this study was to investigate the potential for UC screening of simple test detecting activated PKCα. Methods: This institutional review board-approved prospective study included patients with bladder cancer or upper urinary tract UC who underwent surgery at Kyushu University Hospital between September 2018 and December 2020. Patients with benign urologic disorders or healthy volunteers were included as a control group. Patients with prostate cancer (PC) or renal cell carcinoma (RCC) who underwent curative surgery were included as other genitourinary (GU) cancer group. Patients with other coexisting malignant tumors were excluded. Urine samples were collected prior to surgery, 20 mL of urine was centrifuged, and the pellet was lysed for analysis. We evaluated the phosphorylation status of the activated PKCα-specific peptide substrate by MALDI-TOF mass spectrometry. The utility of activated PKCα as a urinary biomarker was evaluated by its sensitivity and negative predictive value when compared to control group or other GU cancers group. Results: Urine samples were obtained from 226 individuals, which included 98 patients with UC, 51 with other GU caners, and 77 with control group. Of the 98 patients with UC, activated PKCα was detected in 75 patients, with sensitivity of 76.5%. The sensitivity in patients with high-grade and low-grade UC were 84% and 62%, respectively. The sensitivity in those with high-grade UC increased to 93% when combined with urine cytology. On the other hand, activated PKCα were rarely detected in non-UC patients which includes other GU cancers group and control group. The specificity among the non-UC patients was 74.2%. In the comparison between patients with UC and non-UC, the negative predictive value of activated PKCα was 80.5%. The area under the receiver operating characteristic curve (AUC) for detecting UC of activated PKCα was 0.80. Conclusions: This study demonstrates the utility of activated PKCα as a novel urine screening test for UC. (Patent Application No. PCT/JP2020/045257) Since this test is based on a single target, inexpensive detection devices can be developed.