Multiple studies have demonstrated that miRNA can serve as excellent biomarkers; they are present and stable in body fluids, they often play a direct role in the disease process, and they are relatively easy and affordable to work with and assess . In our recent article , we demonstrate that miRNA can be extracted from canine urine and that miR-103b and miR-16 expression levels can be used to distinguish between canine patients with TCC versus clinically normal patients as well as between TCC patients and patients with lower tract urinary disease (LUTD). The latter is important because TCC and LUTD patients often share many of the same signs and symptoms, and this can result in misdiagnosis and delayed treatment. It is noteworthy that in our study we observed statistically significant differences in miRNA expression only in urine samples, not blood samples. This finding, and the fact that alterations in miRNA expression which are observed in urine samples are more likely to reflect actual changes in miRNA expression which are occurring in bladder cells because they are shed into the urine [5, 6], supports the use of urine for TCC biomarker discovery studies.
To our knowledge, our study is the first to observe differential expression of miR-103b and miR-16 in urine samples from canine bladder cancer patients versus patients with LUTD. Decreased miR-103b expression has been observed in human patients with muscle-invasive bladder cancer (MIBC) and is associated with worse outcome , and dysregulation of miR-103b can result in altered expression of several molecules which play a role in carcinogenesis, for example, CCNE1, CDK2, CREB1, DICER, and PTEN  . Decreased miR-103b expression has also been shown to promote increased proliferation and invasiveness in colorectal cancer cell lines [8, 10, 11]. A role for miR-16 in bladder carcinogenesis, or differential expression of miR-16 in TCC, has not previously been reported, however, decreased expression of miR-16 is associated with chronic lymphocytic lymphoma (CLL) and prostate cancer [12-14]. The combined data support further investigation of miR-103b and miR-16 as potential biomarkers for both canine and human TCC.
Another key finding from our study is that loss of coordinated expression of some of the urine-derived miRNAs assessed, including miR-34a, occurs in canine TCC patients. MiR-34a is well known to be regulated by p53 and dysregulation of the p53 signaling axis is a hallmark of advanced TCC [15, 16]. While further analyses are needed to validate this preliminary finding, our data indicate analysis of multiple miRNAs and their relative expression to each other within each patient sample may be a promising strategy for TCC biomarker discovery studies.
- Fulkerson CM, Knapp DW: Management of transitional cell carcinoma of the urinary bladder in dogs: a review. Vet J 2015, 205(2):217-225.
- von der Maase H, Sengelov L, Roberts JT, Ricci S, Dogliotti L, Oliver T, Moore MJ, Zimmermann A, Arning M: Long-term survival results of a randomized trial comparing gemcitabine plus cisplatin, with methotrexate, vinblastine, doxorubicin, plus cisplatin in patients with bladder cancer. J Clin Oncol 2005, 23(21):4602-4608.
- Weber JA, Baxter DH, Zhang S, Huang DY, Huang KH, Lee MJ, Galas DJ, Wang K: The microRNA spectrum in 12 body fluids. Clin Chem 2010, 56(11):1733-1741.
- Kent MS, Zwingenberger A, Westropp JL, Barrett LE, Durbin-Johnson BP, Ghosh P, Vinall RL: MicroRNA profiling of dogs with transitional cell carcinoma of the bladder using blood and urine samples. BMC Vet Res 2017, 13(1):339.
- Reine NJ, Langston CE: Urinalysis interpretation: how to squeeze out the maximum information from a small sample. Clin Tech Small Anim Pract 2005, 20(1):2-10.
- Fogazzi GB, Garigali G: The clinical art and science of urine microscopy. Curr Opin Nephrol Hypertens 2003, 12(6):625-632.
- Jiang X, Du L, Duan W, Wang R, Yan K, Wang L, Li J, Zheng G, Zhang X, Yang Y et al: Serum microRNA expression signatures as novel noninvasive biomarkers for prediction and prognosis of muscle-invasive bladder cancer. Oncotarget 2016.
- Geng L, Sun B, Gao B, Wang Z, Quan C, Wei F, Fang XD: MicroRNA-103 promotes colorectal cancer by targeting tumor suppressor DICER and PTEN. International journal of molecular sciences 2014, 15(5):8458-8472.
- Liao Y, Lonnerdal B: Global microRNA characterization reveals that miR-103 is involved in IGF-1 stimulated mouse intestinal cell proliferation. PLoS One, 5(9):e12976.
- Hong Z, Feng Z, Sai Z, Tao S: PER3, a novel target of miR-103, plays a suppressive role in colorectal cancer in vitro. BMB reports 2014, 47(9):500-505.
- Chen HY, Lin YM, Chung HC, Lang YD, Lin CJ, Huang J, Wang WC, Lin FM, Chen Z, Huang HD et al: miR-103/107 promote metastasis of colorectal cancer by targeting the metastasis suppressors DAPK and KLF4. Cancer research 2012, 72(14):3631-3641.
- Nana-Sinkam SP, Croce CM: MicroRNA in chronic lymphocytic leukemia: transitioning from laboratory-based investigation to clinical application. Cancer genetics and cytogenetics 2010, 203(2):127-133.
- Aqeilan RI, Calin GA, Croce CM: miR-15a and miR-16-1 in cancer: discovery, function and future perspectives. Cell death and differentiation 2010, 17(2):215-220.
- Cho WC: OncomiRs: the discovery and progress of microRNAs in cancers. Molecular cancer 2007, 6:60.
- Wolff EM, Liang G, Jones PA: Mechanisms of Disease: genetic and epigenetic alterations that drive bladder cancer. Nat Clin Pract Urol 2005, 2(10):502-510.
- Rokavec M, Li H, Jiang L, Hermeking H: The p53/miR-34 axis in development and disease. J Mol Cell Biol 2014, 6(3):214-230.
Ruth L. Vinall1, Michael Kent2, and Paramita M. Ghosh3
1. Department Pharmaceutical & Biomedical Sciences, California Northstate University College of Pharmacy, Elk Grove, CA
2. Department of Surgical and Radiological Sciences, School of Veterinary Medicine, University of California, Davis, CA
3. Department of Urology, University of California Davis, Sacramento, CA
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