Expression Of Legumain And Prognostic Outcome In Uveal Melanoma

[objective] In adults, uveal melanoma is the most common malignant intraocular tumor, which originated from melanocytes. Because of its rich circulation of blood, uveal melanoma can disseminate hematogenously, which preferentially metastasizes to the liver, and metastasis is the main cause of death. Especially insidious potential is the main character of UM metastasis, so at the time of diagnosis, many patients may have subclinical metastasis, which underscores the critical need to identify prognostic markers indicative of uveal melanoma invasive metastatic potential. Legumain, an novel asparaginyl endopeptidase, is expressed in some humam solid carcinoma, whereas it can not been detected in normal tissures, whose overexpression has been shown to be combined with increased migration, invasion, and metastasis in some solid carcinaoma. In our study, to make sure the expression of legumain in uveal melanoma, and to investigate its prognostic value in the patients of uveal melanoma and its relationship with other prognostic factors (cell type, tumor size, metastasis, involvement of optic nerve, and extent of invasion) in uveal melanoma.[Methods] In our study, firstly, to detect legumain in two uveal melanoma cell lines by using RT-PCR and western-blot, after the culture of cell lines and extraction of RNA and protein from cell lines. Simultaneously, immunofluorescence staining can be used to show the expression of legumain in uveal melanoma cell lines. Secondly, Paraffin-embedded sections from 82 clinicopathologically well-characterized cases of primary uveal melanoma were immunohistochemically stained for legumain. Legumain expression was evaluated in terms of both the intensity and the extent of staining for each specimen. Thirdly, to investigate the relationship between the expression of legumain and prognostic outcome of uveal melanoma patients through Kaplan-Meier univariate analysis and Log-rank, Brelow, Tarone-Ware tests, and some other prognostic risk factors were to be determined after the prognostic risk factors wre preliminary srcreened respectively with Kaplan-Meier univariate analysis and Log-rank, Brelow, Tarone-Ware tests. Last but not least, we investigated the relationship between the expression of legumain and other prognostic risk factors through bivariate correlation analysis. [Results] In our experiment, the expression of legumain was detected in two uveal melanoma cell lines by using RT-PCR, western-blot and immunofluorescence staining, and especially the expression of legumain was more obvious in Mum-2B cell line by western-blot. Both positive and negative expression of legumain can be shown in the three main cell types of uveal melanoma (epitheloid, spindle, mixed cell) by immunohistochemically staining for paraffin-embedded sections from 82 cases of uveal melanoma. Through Kaplan-Meier univariate analysis and Log-rank, Brelow, Tarone-Ware tests, the expression of legumain, cell type, tumor size, metastasis, involvement of optic nerve, and extent of invasion (P<0.05) except sex (P>0.05) had not only great influence on the prognosis of uveal melanoma patients, but also the expression of legumain had positive correlations with other prognostic risk factors including cell type, tumor size, metastasis, involvement of optic nerve, and extent of invasion (P<0.01), especially with the extent of invasion (correlation coefficient> 0.5), by using bivariate correlation analysis.[Conclusion] In this study, by detecting legumain in the two cell lines of uveal melanomna and paraffin-embedded sections from 82 cases of uveal melanoma, it can be proved that legumain was expressed in uveal melanoma, and in combination with clinical data, through survival study and correlation analysis, it is to find that upregulation of legumain expression appears to be associated with poor prognosis in uveal melanoma, and also has positive correlations with other prognostic risk factors. Therefore, legumain is not only a valuable predictive marker for prognosis of uveal melanoma patients, but also it is involved in the pathgenesis and progress of uveal melanoma. In the near future, legumain may be the important target for effective treatment of uveal melanoma.