Multiple roles of Equarin during lens development

Loss of DRO1/CCDC80 in the tumor microenvironment promotes carcinogenesis

Tumors are composed of the tumor cells and the surrounding microenvironment. Both are closely interwoven and interact by a complex and multifaceted cross-talk which plays an integral part in tumor initiation, growth, and progression. Dro1/Ccdc80 has been shown to be a potent suppressor of colorectal cancer and ubiquitous inactivation of Dro1/Ccdc80 strongly promoted colorectal carcinogenesis in Apc^Min/+ mice and in a chemically-induced colorectal cancer model.

The aim of the present study was to investigate whether Dro1/Ccdc80’s tumor suppressive function is tumor-cell-autonomous. Expression of Dro1/Ccdc80 in cancer cells had no effect on both colon tumor development in Apc^Min/+ mice and formation of xenograft tumors. In contrast, DRO1/CCDC80 loss in the microenvironment strongly increased tumor growth in xenograft models, inhibited cancer cell apoptosis, and promoted intestinal epithelial cell migration. Moreover, stromal Dro1/Ccdc80 inactivation facilitated formation of intestinal epithelial organoids. Expression analyses showed Dro1/Ccdc80 to be significantly down-regulated in murine gastric cancer associated fibroblasts, in Apc^Min/+ colon tumor primary stromal cells and in microdissected stroma from human colorectal cancer compared to normal, non-tumor stroma. Our results demonstrate epithelial derived DRO1/CCDC80 to be dispensable for intestinal tissue homeostasis and identify Dro1/Ccdc80 as tumor suppressor in the tumor microenvironment.

Aqueous humour-induced lens epithelial cell proliferation requires FGF-signalling

The eye lens grows by systematic proliferation of its epithelial cells and their differentiation into fibre cells. The anterior aqueous humour regulates lens epithelial cell proliferation whereas posteriorly, the vitreous stimulates lens fibre differentiation. Vitreous-derived members of the fibroblast growth factor (FGF) family induce fibre differentiation, with added support for FGFs as putative regulators of aqueous-induced lens cell proliferation. To further characterize this, given FGFs' known affinity for proteoglycans, we compared the effect of proteoglycan sulphation in growth factor- and aqueous-induced lens cell proliferation. Disruption of proteoglycan sulphation in lens cells specifically impacted on aqueous- and FGF-induced MAPK/ERK1/2-signalling, but not on that induced by other mitogens such as PDGF; however, cell proliferation was reduced in all treatment groups, regardless of the mitogen. Overall, by disrupting proteoglycan activity, we further highlight the significant role of FGFs in aqueous-induced ERK1/2 phosphorylation leading to lens cell proliferation.