Abstract
Purpose :
Uveal melanoma (UM) is the most common intraocular tumor affecting adults. Approximately 50% of patients diagnosed with uveal melanoma develop metastasis to the liver. Prognosis following metastasis is poor with an 82% mortality rate in the first year. Because there is no current treatment, there is a significant need to discover possible targets for therapy in metastatic uveal melanoma. We determined that one such target could be the TP53-MDM2 signaling pathway. More specifically, we hypothesize that cytoplasmic retention of p14ARF contributes directly uveal melanoma metastasis.
Methods :
We analyzed three different UM cell lines using qPCR, multispectral imaging flow cytometry, and immunofluorescence. Our cell lines included a primary tumor cell line that did not present with metastasis (Mel 290), a primary tumor cell line that did present with metastasis to the liver (Mel 270), and a metastatic cell line (OMM 2.5). Using the multispectral imaging flow cytometry and immunofluorescence, we were able to analyze the localization of both p14ARF and p-MDM2 and determine differences between each cell line.
Results :
Both the multispectral imaging flow cytometry and immunofluorescence showed high levels of p14ARF in the nucleus of the primary tumor cell lines. However, levels of nuclear p14ARF were diminished in the metastatic cell line. Diminished levels of nuclear p14ARF lead to increased activity of p-MDM2. This increase in p-MDM2 activity could lead directly to increased tumor growth, proliferation, and metastasis.
Conclusions :
Our results are consistent with our hypothesis that cytoplasmic retention of p14ARF may directly contribute to UM metastasis. Further work is needed to determine levels of complexed p-MDM2 and p14ARF in the nucleus of each cell line.
This abstract was presented at the 2019 ARVO Annual Meeting, held in Vancouver, Canada, April 28 - May 2, 2019.