The addition of 50% vitreous humor to the media bathing lens explants results in the induction of both fiber cell differentiation and a significant immune/inflammatory response. Although Fgfr loss blocks differentiation in lens epithelial explants, this loss is partially rescued by deleting Pten. To investigate the functions of the Fgfrs and Pten during lens fiber cell differentiation, we utilized a lens epithelial explant system and conducted RNA sequencing on vitreous humor-exposed explants lacking Fgfrs, or Pten or both Fgfrs and Pten. We found that Fgfr loss impairs both vitreous-induced differentiation and inflammation while the additional loss of Pten restores these responses. Furthermore, transcriptomic analysis suggested that PDGFR-signaling in FGFR-deficient explants is required to mediate the rescue of vitreous-induced fiber differentiation in explants lacking both Fgfrs and Pten. The blockage of β-crystallin induction in explants lacking both Fgfrs and Pten in the presence of a PDGFR-inhibitor supports this hypothesis. Our findings demonstrate that a wide array of genes associated with fiber cell differentiation are downstream of FGFR-signaling and that the vitreous-induced immune responses also depend on FGFR-signaling. Our data also demonstrates that many of the vitreous-induced gene expression changes Fgfr-deficient explants are rescued in explants lacking both Fgfrs and Pten.

Purpose: To analyze the genetic and molecular profile of liver nodules in the context of Fontan-associated liver disease (FALD) with the aim of identifying possible biomarkers for predictive outcome and personalized therapy. Methods: this retrospective monocentric study included 9 patients who developed FALD in the context of congestive cirrhosis:1 regenerative nodular hyperplasia, 2 hepatic adenomas (HA) and 4 hepatocellular carcinoma (HCC), 1 fibrolamellar carcinoma (FLC) and 1 intrahepatic cholangiocarcinoma (ICC). The lesions were analyzed by histology and immunohistochemistry (b-catenin, glypican 3, glutamine synthetase and SOX9). To study the molecular profile of neoplastic FALD, targeted NGS was performed on DNA and RNA from formalin-fixed paraffin embedded neoplastic liver tissue of 1 HA, 2 HCCs, 1 FLC and 1 ICC. Results: Molecular analysis showed 3 patients with copy number alteration involving FGFR3, and one patient with a hotspot mutation on CTNNB1 and NRAS genes. All 5 patients showed a tumor mutational burden ranging from low to intermediate. Variants of unknown significance in GNAS were present in 2 HCC and 1 ICC. The single FLC had a DNAJB1-PRKACA fusion. Conclusions: The molecular results seem to be consistent with a peculiar molecular profile of the malignant FALD which may be useful for new target therapies for HCC/ICC in FALD.