A biomedical engineer at the University of Houston and his team of researchers are reporting the discovery of new biomarkers for early detection of bladder cancer, among the most common cancers diagnosed in men in the United States.

According to the American Cancer Society (ACS), more than 62,000 cases have been diagnosed in men and nearly 20,000 in women so far in 2023.

The risk of developing BC increases with age with the highest risk being in 80-year-old males and females [1]. The 5-year relative survival rate for those with BC is 77% [2]. If the tumor is non-invasive, the 5-year survival increases to 96% [2]. However, 51% of all cases are diagnosed after this occurrence [2].

Gold standard
The current gold standard for the diagnosis of bladder cancer is invasive cystoscopy wherein a thin camera is inserted into the tiny urethra to peer inside. It is associated with complications including pain, urinary tract infection and hematuria, or blood in the urine. It also often lacks the sensitivity to correctly identify the disease.

Soon, a simple urine test, with examination of collected cells, may be the new standard.

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“Using aptamer-based screening, we analyzed the expression of 1,317 proteins in the urine of bladder cancer patients and found that D-dimer – a protein fragment from the breakdown of a blood clot – may have a role in the initial diagnosis or detection of cancer recurrence,” reports Chandra Mohan, MBBS/MD, Ph.D., the Hugh Roy and Lillie Cranz Cullen Endowed Professor of biomedical engineering, in BMC Medicine. [3]

In contrast to previous studies in the field examining a handful of proteins selected based on their known properties, in this work Mohan reports the first and largest use of the comprehensive aptamer-based proteomic screen of urine samples from 42 subjects.

Aptamers are short, single-stranded DNA or RNA. In recent years, aptamers have come to replace antibodies in high throughput experiments. The aptamer-based biomarker screening technology is capable of examining thousands of proteins in a very small sample volume. For more than a decade Mohan has been proving the success of this method, using it to discover disease biomarkers.

Study results
A systems biology analysis implicated molecular functions related to the extracellular matrix, collagen, integrin, heparin, and transmembrane tyrosine kinase signaling in bladder cancer susceptibility, with HNF4A and NFKB1 emerging as key molecular regulators. STEM analysis of the dysregulated pathways implicated a functional role for the immune system, complement, and interleukins in bladder cancer disease progression.[3]

During the screening, of the 21 urine proteins discriminating bladder cancer from urology clinic controls, urine D-dimer displayed the highest accuracy (96%) and sensitivity of 97%.

In addition, 8 urine proteins significantly discriminated MIBC from NMIBC (AUC = 0.75–0.99), with IL-8 and IgA being the best performers. Urine IgA and fibronectin exhibited the highest specificity of 80% at fixed sensitivity for identifying advanced BC.

Largest ELISA validation study
Also in the present study, Mohan executed the largest Enzyme-Linked Immunosorbent Assay (ELISA) validation study in bladder cancer, examining 30 protein biomarkers in an independent cohort consisting of 68 subjects.

ELISA is a powerful tool that has fueled the engineering of hundreds of diagnostic tests used in hospitals today. It allows for detection of a wide range of molecules with high sensitivity and specificity.

Mohan also found eight urine proteins significantly discriminated muscle invasive bladder cancer from non-muscle invasive bladder cancer with Interleuking-8 (IL-8) and IgA being the best performers.

“Urine IL-8 and IgA may have the potential in identifying disease progression during patient follow-up. The use of these biomarkers for initial triage could have a significant impact as the current cystoscopy-based diagnostic and surveillance approach is costly and invasive when compared to a simple urine test,” said Mohan.

Urine samples for this study were obtained from the University of Texas Southwestern Medical Center and Bioreclamation.

These studies were carried out by graduate student Jessica Castillo and senior researcher Kamala Vanarsa in collaboration with Yair Lotan, MD, at University of Texas Southwestern Medical Center.

Reference
[1] Richters A, Aben KKH, Kiemeney LALM. The global burden of urinary bladder cancer: an update. World J Urol. 2020 Aug;38(8):1895-1904. doi: 10.1007/s00345-019-02984-4. Epub 2019 Nov 1. PMID: 31676912; PMCID: PMC7363726
[2] Cancer facts and statistics: American Cancer Society (ACS) Online. Last accessed on April 26, 2023.
[3] Vanarsa K, Castillo J, Wang L, Lee KH, Pedroza C, Lotan Y, Mohan C. Comprehensive proteomics and platform validation of urinary biomarkers for bladder cancer diagnosis and staging. BMC Med. 2023 Apr 5;21(1):133. doi: 10.1186/s12916-023-02813-x. PMID: 37016361; PMCID: PMC10074794.

Featured image urine collection kit. Photo courtesy: © 2016 – 2023 PxFuel. Used with permission.

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