BACR 11: Role of hypoxia-induced ADAM10 in colorectal cancer biology
1School of Biological, Biomedical and Environmental Sciences, University of Hull, Hull, UK
The hypoxic tumour microenvironment has been strongly implicated in cancer progression and increased metastatic potential. The ADAMs (A Disintegrin And Metalloproteinase) family have been implicated in cancer and hypoxia-associated progression. Evidence regarding a lesser-studied member of the ADAMs family, ADAM10, in hypoxia-mediated progression is lacking. Here, we aim to investigate the effect of severe hypoxia on ADAM10 expression and function in colorectal cancer cell line models.
Colorectal cancer cell lines were exposed to severe hypoxia (0.5% O2) and the expression of ADAM10 examined at both protein and transcriptional levels. MTS assays were used to assess the role of ADAM10 in cellular viability. Levels of signalling cascades targeted by ADAM10 were analysed by Western Blotting. Subsequently, downstream targets of the NOTCH signalling cascade were examined by qPCR.
An upregulation of ADAM10 was observed at protein level after exposure to severe hypoxia, importantly in the processed, active form. A previously unidentified, hypoxia-mediated doublet form of mature ADAM10 was identified. Furthermore, we observed a decrease in cell viability, as an indication of proliferation, in hypoxia, following ADAM10 knockdown. qPCR analysis showed no significant effect of hypoxia or ADAM10 silencing on NOTCH1 and HES-1 transcript levels. Interestingly, an ADAM10-dependent downregulation of c-MYC transcript was observed, independently of hypoxia. Finally, a hypoxia-dependent decrease in CCND1 was seen, further enhanced upon ADAM10 knockdown.
So far we have shown an upregulation of ADAM10 in hypoxia, particularly in the processed active form. The occurrence of a hypoxia-mediated doublet suggests potential hypoxia-dependent post-translational modification of ADAM10. Our results indicate that ADAM10 plays a role in driving cellular proliferation in hypoxia, thus implicating it as a novel regulator of hypoxia-mediated colorectal cancer progression.