Postdoctoral Research Fellow Mayo Clinic Jacksonville Jacksonville, Florida, United States
Introduction: Extracellular matrix (ECM) and its accumulation has been shown to correlate with tumor aggressiveness in different cancer types, including glioblastoma (GBM). Hyaluronan (HA) is a major component of the ECM. HA synthesis is regulated by UDP-GlcNAc levels, which in turn are controlled by the enzymatic activity of UAP1. Our team has developed a UAP1 inhibitor designed to reduce UDP-GlcNAc levels, as a novel therapy to fight GBM. Here, we aimed to determine the effects of pharmacological inhibition of UAP1 in vitro on primary GBM patient-derived cell lines assessing the regulation of HA pathway, and GBM cytotoxic response.
Methods: Expression of hyaluronidase 2 (HAS2) and UAP1 in GBM was investigated using public databases. 2 primary GBM patient-derived cell lines were utilized to determine the UAP1 inhibitor IC50. Expression of key genes in the HA biosynthetic pathway (HAS2, HYAL1, HYAL2) was measured by RT-qPCR and immunofluorescence. Cell viability was measured by Cyquant analysis and apoptosis by annexin V/7ADD, caspase3/7 activation and ethidium homodimer.
Results: Hyaluronidases are highly expressed in GBM tumors and correlates with UAP1 expression (p= < 0.001). Moreover, our results showed that HAS2 is downregulated (p= < 0.01) and HYAL1 is upregulated (p= < 0.05) at 48 hours after treatment in vitro. Furthermore, at 72 hours, increased apoptosis and reduction in proliferation was shown. (p= < 0.001).
Conclusion : Inhibition of UAP1 reduces HAS expression and increases hyaluronidase activity at 48 hours. This is followed by a proliferation arrest and an increase in apoptosis at a 72-hour timepoint suggesting UAP1 inhibition as a novel tool to fight glioblastoma malignancy. Further in vivo studies are needed to fully evaluate the effects of our drug on the ECM, including the interaction with the immune landscape.
