YO2 Induces Melanoma Cell Apoptosis through p53-Mediated LRP1 Downregulation

SIMPLE SUMMARY: We found that induction of tumor suppressor p53 in melanoma cells suppressed tumor growth by targeting LRP1 expression. LRP1 downregulation was achieved by the micro RNAs miR103/107. We identify the small molecule YO-2 as an inducer of tumor suppressor p53. We propose that YO-2, combined with myelosuppressive drugs like doxorubicin, can be a novel treatment option. ABSTRACT: The multifunctional endocytic receptor low-density lipoprotein receptor-related protein 1 (LRP1) has been implicated in melanoma growth. However, the mechanism of LRP1 expression in melanoma cells remains only partially understood. In most melanomas, the TP53 tumor suppressor is retained as a non-mutated, inactive form that fails to suppress tumors. We identify TP53 as a regulator of LRP1-mediated tumor growth. TP53 enhances the expression of miRNA miR-103/107. These miRNAs target LRP1 expression on melanoma cells. TP53 overexpression in human and murine melanoma cells was achieved using lentivirus or treatment with the small molecule YO-2, a plasmin inhibitor known to induce apoptosis in various cancer cell lines. TP53 restoration enhanced the expression of the tumor suppressor miR-103/107, resulting in the downregulation of LRP1 and suppression of tumor growth in vivo and in vitro. Furthermore, LRP1 overexpression or p53 downregulation prevented YO-2-mediated melanoma growth inhibition. We identified YO-2 as a novel p53 inducer in melanoma cells. Cotreatment of YO-2 with doxorubicin blocked tumor growth in vivo and in a murine melanoma model, suggesting that YO-2 exerts anti-melanoma effects alone or in combination with conventional myelosuppressive drugs.