Suicide-Gene-Modified Extracellular Vesicles of Human Primary Uveal Melanoma in Future Therapies

Abstract

Extracellular vesicles secreted from uveal melanoma (UM) cells are involved in the establishment of the premetastatic niche and display transforming potential for the formation of metastases, preferentially in the liver. In this study, we cultivated human primary UM cells and uveal melanoma-associated fibroblasts in vitro to be transduced by infection with a retrovirus containing the suicide gene—fused yeast cytosine deaminase::uracil phospho-ribosyl transferase (yCD::UPRT). A homogenous population of yCD::UPRT-UM cells with the integrated provirus expressed the gene, and we found it to continuously secrete small extracellular vesicles (sEVs) possessing mRNA of the suicide gene. The yCD::UPRT-UM-sEVs were internalized by tumor cells to the intracellular conversion of the prodrug 5-fluorocytosine (5-FC) to the cytotoxic drug 5-fluorouracil (5-FU). The host range of the yCD::UPRT-UM-sEVs was not limited to UMs only. The yCD::UPRT-UM-sEVs inhibited the growth of the human cutaneous melanoma cell line A375 and uveal melanoma cell line MP38, as well as other primary UMs, to various extents in vitro. The yCD::UPRT-UM-sEVs hold the therapeutic and prophylactic potential to become a therapeutic drug for UM. However, the use of yCD::UPRT-UM-sEVs must first be tested in animal preclinical studies.

Participation of suicide gene extracellular vesicles in metastasis prevention

“…Thanks to these features, tumor-derived EVs are attractive targets for anti-cancer drug modification. EVs possessing suicide gene message secreted from either mesenchymal stem/stromal cells [17], or from tumor cells [31,32], having the ability to convert non-toxic compound to cytotoxic drug intracellularly, are a promising treatment option for metastatic tumors that are untreatable at present.…”

“…Tumor cell-derived yCD::UPRT suicide gene-EVs inhibiting pre-metastatic niche creation or damaging it, may lead to metastasis prevention [31]. Similarly, EVs secreted from uveal melanoma modified with yCD::UPRT suicide gene [32], when systemically repeatedly applied with 5-FC prodrug could be the way how to prevent metastasis. The inference with circulating tumor cells or prevention of proper niche creation are the mechanisms leading to metastasis prevention.…”