KRAS mutations as essential promoters of lymphangiogenesis via extracellular vesicles in pancreatic cancer

Abstract

Kirsten rat sarcoma virus (KRAS) gene mutations are present in more than 90% of pancreatic ductal adenocarcinomas (PDACs). KRASG12D is the most frequent alteration, promoting preneoplastic lesions and associating with a more aggressive phenotype. These tumors possess increased intratumoral lymphatic networks and frequent lymph node (LN) metastases. In this issue of the JCI, Luo, Li, et al. explored the relationship between the presence of the KRASG12D mutation and lymphangiogenesis in PDAC. The authors used in vitro and in vivo models and an elegant mechanistic approach to describe an alternative pathway for lymphangiogenesis promotion. KRASG12D induced SUMOylation of heterogenous nuclear ribonucleoprotein A1 (hnRNPA1) via SAE1 and SUMO2 activation. SUMOylated hnRNPA1 was loaded into extracellular vesicles (EVs) and internalized by human endothelial lymphatic cells (HLEC). Further, SUMOylated hnRNPA1 promoted lymphangiogenesis and LN metastasis by stabilizing prospero homeodomain protein 1 (PROX1) mRNA. These data provide mechanistic insight into cancer lymphangiogenesis with the potential for developing biomarkers and RAS pathway therapeutics.

Figure 1. The proposed mechanism of KRASG12D-induced lymphangiogenesis in PDAC.

PDAC cells with the KRAS^G12D mutation upregulate SAE1, which triggers SUMOylation. Subsequent SUMOylation of hnRNPA1 at lysine 113 enables interaction with a component of the endosomal sorting complex, TSG101. EVs are loaded with SUMOylated hnRNPA1 and released into the tumor microenvironment. Local lymphatic endothelial cells internalizing EVs via endocytosis acquire elevated SUMOylated hnRNPA1, stabilizing PROX1 mRNA to increase PROX1 expression and lymphangiogenesis.