Rushton Jessica G, Ertl Reinhard, Klein Dieter, Tichy Alexander, Nell Barbara
1 Department for Companion Animals and Horses, Vetmeduni Vienna, Vienna, Austria.
2 VetCore Facility for Research, Vetmeduni Vienna, Vienna, Austria.
J Feline Med Surg. 2019 Feb;21(2):124-132. doi: 10.1177/1098612X18762017. Epub 2018 Mar 13.
Feline diffuse iris melanoma (FDIM) is the most common malignant primary intraocular tumour in cats, with reported metastases rates between 19% and 63%. Currently, the only available diagnostic tool for a tentative diagnosis is histopathological examination of the enucleated eye. Therefore, the veterinary ophthalmologist is often faced with the dilemma of whether to enucleate an oftentimes visual eye or to continue monitoring, with the risk of metastases developing. In the past, cell-free DNA (cfDNA) gained more attention in human medicine, especially in the field of oncology. Prior studies have shown the use of cfDNA as diagnostic or prognostic markers in canine and human cancer patients. Therefore, the aim of this study was to investigate cfDNA concentration and integrity in cats with FDIMs compared with cats with benign iris naevi and without ocular abnormalities.
cfDNA from plasma of cats with iris melanoma (n = 34), iris naevus (n = 30) and without ocular abnormalities (n = 32) were extracted. Primer and probes for feline amyloid beta precursor protein ( APP) and beta actin ( ACTB) were designed for amplicons of various lengths and quantitative PCRs of extracted cfDNA were performed to measure cfDNA concentration and integrity of the plasma samples. Differences of cfDNA concentrations and integrity levels between the three groups (iris melanoma, iris naevi and controls) were analysed using the Mann-Whitney U-test.
cfDNA concentration and integrity analysis revealed no significant differences between the cats with iris melanoma, iris naevus or the control group ( P >0.01). Cats with metastases showed similar cfDNA concentration and integrity to cats without metastases.
cfDNA concentration and integrity seem to be insufficient as a diagnostic or prognostic marker in cats with FDIMs.
猫弥漫性虹膜黑色素瘤（FDIM）是猫最常见的原发性眼内恶性肿瘤，据报道转移率在19%至63%之间。目前，唯一可用于初步诊断的工具是对摘除眼球进行组织病理学检查。因此，兽医眼科医生常常面临两难抉择，即是否摘除一只通常仍有视力的眼睛，还是继续监测，但存在发生转移的风险。过去，游离DNA（cfDNA）在人类医学中受到更多关注，尤其是在肿瘤学领域。先前的研究表明，cfDNA可作为犬类和人类癌症患者的诊断或预后标志物。因此，本研究的目的是调查患有FDIM的猫与患有良性虹膜痣且无眼部异常的猫的cfDNA浓度和完整性。
提取患有虹膜黑色素瘤（n = 34）、虹膜痣（n = 30）和无眼部异常（n = 32）的猫血浆中的cfDNA。针对猫淀粉样β前体蛋白（APP）和β肌动蛋白（ACTB）设计了不同长度扩增子的引物和探针，并对提取的cfDNA进行定量PCR，以测量血浆样本中cfDNA的浓度和完整性。使用Mann-Whitney U检验分析三组（虹膜黑色素瘤、虹膜痣和对照组）之间cfDNA浓度和完整性水平的差异。
cfDNA浓度和完整性分析显示，患有虹膜黑色素瘤的猫、患有虹膜痣的猫或对照组之间无显著差异（P > 0.01）。有转移的猫与无转移的猫的cfDNA浓度和完整性相似。
cfDNA浓度和完整性似乎不足以作为FDIM猫的诊断或预后标志物。
