MicroRNAs as tumour suppressors in canine and human melanoma cells and as a prognostic factor in canine melanomas

Malignant melanoma (MM) is one of the most aggressive cancers in dogs and in humans. However, the molecular mechanisms of its development and progression remain unclear. Presently, we examined the expression profile of microRNAs (miRs) in canine oral MM tissues and paired normal oral mucosa tissues by using the microRNA‐microarray assay and quantitative RT‐PCR. Importantly, a decreased expression of miR‐203 was significantly associated with a shorter survival time. Also, miR‐203 and ‐205 were markedly down‐regulated in canine and human MM cell lines tested. Furthermore, the ectopic expression of miR‐205 had a significant inhibitory effect on the cell growth of canine and human melanoma cells tested by targeting erbb3. Our data suggest that miR‐203 is a new prognostic factor in canine oral MMs and that miR‐205 functions as a tumour suppressor by targeting erbb3 in both canine and human MM cells.     

CASE REPORT: Iridociliary melanoma with secondary lens luxation: distinctive findings in a long‐horned cowfish (Lactoria cornuta)

This report describes a long‐horned cowfish, which was diagnosed with buphthalmia and lens sub‐luxation in the right eye, conditions that progressed to complete anterior lens luxation and secondary keratoconus. Three months after the initial evaluation, a pigmented mass was observed protruding from the vitreous. An enucleation was performed under general anesthesia. Ocular histopathology revealed an iridociliary melanoma. Reports of intraocular melanomas are extremely rare in fish. To the authors’ knowledge, this is the first report of an iridociliary melanoma that led to buphthalmia, lens luxation, and keratoconus in a fish. Histological findings of lens luxation are also demonstrated. Due to the presence of a complex suspensory apparatus involving the teleost lens, this report speculates that lens luxation is a more devastating disease process in teleosts than in mammals.     

Suspected latent vertebral metastasis of uveal melanoma in a dog: a case report

A six-year-old intact male Pomeranian was examined because of right eye discomfort. An iris neoplasm was suspected and the eye was enucleated. A uveal melanoma with malignant features was diagnosed. The dog recovered uneventfully from surgery. A general physical examination was performed at 3-month intervals afterwards without any detectable problem, but 18 months after the first presentation the dog suffered a rapid, progressive paraplegia. Radiographic examination and myelography revealed a spinal cord compression at the level of the 8th thoracic (T8) vertebral body. Surgical exploration of the area revealed a potential vertebral neoplasm: histopathology confirmed a melanoma which was suspected to have resulted from metastasis from the previously diagnosed uveal melanoma.