METHODS: In the present studies, the consequence of PPARβ/δ inhibition either by global genetic deletion or by a specific PPARβ/δ antagonist, 10h, on malignant transformation of melanoma cells and melanoma metastasis was examined using both in vitro and in vivo models.
RESULTS: Our study showed that 10h promotes epithelial-mesenchymal transition (EMT), migration, adhesion, invasion and trans-endothelial migration of mouse melanoma B16/F10 cells. We further demonstrated an increased tumour cell extravasation in the lungs of wild-type mice subjected to 10h treatment and in Pparβ/δ-/- mice in an experimental mouse model of blood-borne pulmonary metastasis by tail vein injection. This observation was further supported by an increased tumour burden in the lungs of Pparβ/δ-/- mice as demonstrated in the same animal model.
CONCLUSION: These results indicated a protective role of PPARβ/δ in melanoma progression and metastasis.
OBJECTIVE: To report two cases of malignant melanoma in the eye, one in the conjunctiva and the other in the choroid.
CASES: The first case was in a 49-year-old lady who presented with a swelling on the inner side of left upper eyelid. The vision was 6/6. On everting the eyelid, multiple, pigmented, nodular swellings were noted on the tarsal conjunctiva. Excision biopsy confirmed the diagnosis of malignant melanoma of the conjunctiva. A pigmented nodular swelling occurred on the lower bulbar conjunctiva in the same eye one-and-a-half years after the first presentation. There were no secondary nodules in the body. Excision biopsy confirmed malignant melanoma of the conjunctiva. The second case was in a 72-year-old lady who presented with pain and bleeding in the right eye. There was no perception of light. The cornea was hazy and the details behind it could not be seen. There was micro perforation of the cornea with oozing of blood and secondary glaucoma. B-scan ultrasonography of the right eye revealed an intraocular tumour. The histopathology of the enucleated eyeball confirmed the diagnosis of malignant melanoma of the choroid.
CONCLUSION: In the case of conjunctival melanoma, the occurrence of tumour at multiple sites and absence of recurrence at the original site suggests the possibility of de novo origin of the tumour. Secondary glaucoma and bleeding may be the presenting features of melanoma in the choroid.