Abstract B020: Delineating the crucial role of fucosyltransferase 4 in facilitating androgen-driven invasiveness and metastatic spread in melanoma
Authors: Liu Qian , Lester Daniel , Adhikari Emma , Koomen John , Fang Bin , Qi Jianfei , Lau Eric 
Published: January 2023

Abstract
Introduction: Melanoma incidence and mortality rate are historically higher for men than women, with an estimated ~34% more new cases and twice the lethality in men in the US in 2022. Consistent with these disparities, recent studies report the tumorigenic role of the male sex hormone androgen and its receptor (AR) in promoting melanoma aggressiveness. However, underlying molecular mechanisms are unclear. We recently discovered a correlation between sex and melanoma fucosylation, the post-translational modification with the dietary sugar L-fucose. Fucosylation determines the stability and activity of targeted proteins by conjugating fucose onto different glycan linkages by 13 fucosyltransferases (FUTs), resulting in divergent cellular interactions and signaling. This study aims to delineate a novel relationship between androgen signaling and fucosylation network in driving melanoma malignancy. We seek to advance our understanding of sex-associated discrepancies in melanoma and to enhance personalized melanoma treatment. Methods: To elucidate the existence and activation of AR in response to androgen in melanoma, we performed immunoblotting, subcellular fractionation, and reporter assays. The biological functions of androgen were assessed via in vitro assays and SM1 melanoma mice model. RT-qPCR and ChIP-qPCR showed the regulation and binding of AR in FUT4 promoter. AR-FUT4 downstream effectors were characterized by phosphoproteomics in CTL/FUT4-expressing melanoma cells ± AR antagonists. Functional In vitro assays validated the biological roles of AR-FUT4 axis in melanoma. Proximity ligation assay evaluated AR-FUT4-modulated junction structures. The TCGA skin cutaneous melanoma dataset (472 cases) was utilized for AR/FUT4 level assessment and gene set enrichment analysis. Results: In general, ~88% of melanoma specimens exhibit detectable AR mRNA levels, which are significantly increased in metastatic tumors. Melanoma cells express androgen-inducible AR, which is transcriptionally active and is responsible for melanoma proliferation and migration. Among 19 fucosylation machinery genes, FUT1, FUT4, SLC35C2, and FUK are predicted to contain canonical AR-binding motifs in their promoter regions. Of those 4 genes, FUT4 mRNA levels are notably upregulated by androgen stimulation. We confirmed the direct binding of AR to the androgen response element in the FUT4 promoter. Functionally, AR potently drives melanoma invasiveness in a FUT4-dependent fashion; however, FUT4 is not crucial for AR-stimulated melanoma proliferation. Adherens junctions (AJs) were identified as key downstream targets of the AR-FUT4 axis that potentially mediate melanoma spread. Specifically, aberrant FUT4 promotes cell invasion by disrupting N-cadherin-mediated junction complexes, in contrast, AR antagonist enhanced the AJs of adjacent cells, hampering melanoma motility. Conclusions: Our results demonstrate that androgen-activated AR signaling potently drives invasive and metastatic capacity in melanoma by inducing FUT4-regulated tumorigenic fucosylation.
Citation Format: Qian Liu, Daniel Lester, Emma Adhikari, John Koomen, Bin Fang, Jianfei Qi, Eric Lau. Delineating the crucial role of fucosyltransferase 4 in facilitating androgen-driven invasiveness and metastatic spread in melanoma [abstract]. In: Proceedings of the AACR Special Conference: Cancer Metastasis; 2022 Nov 14-17; Portland, OR. Philadelphia (PA): AACR; Cancer Res 2022;83(2 Suppl_2):Abstract nr B020.