Theranostics 2019; 9(12):3410-3424. doi:10.7150/thno.32615

Research Paper

O-GlcNAc modification of Sox2 regulates self-renewal in pancreatic cancer by promoting its stability

Nikita S Sharma1, Vineet K Gupta1, Patricia Dauer2, Kousik Kesh1, Roey Hadad1, Bhuwan Giri1, Anjali Chandra5, Vikas Dudeja1,4, Chad Slawson3, Santanu Banerjee1,4, Selwyn M Vickers6, Ashok Saluja1,4, Sulagna Banerjee1,4✉

1. Department of Surgery, University of Miami, Miami, FL.
2. Department of Pharmacology, University of Minnesota, Minneapolis Minnesota.
3. University of Kansas Medical Center, Kansas City, KS.
4. Sylvester Comprehensive Cancer Center, Miami, FL.
5. Department of Psychology, Harvard University.
6. School of Medicine Dean's Office, University of Alabama at Birmingham.

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Citation:
Sharma NS, Gupta VK, Dauer P, Kesh K, Hadad R, Giri B, Chandra A, Dudeja V, Slawson C, Banerjee S, Vickers SM, Saluja A, Banerjee S. O-GlcNAc modification of Sox2 regulates self-renewal in pancreatic cancer by promoting its stability. Theranostics 2019; 9(12):3410-3424. doi:10.7150/thno.32615. Available from http://www.thno.org/v09p3410.htm

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Abstract

Pancreatic adenocarcinoma (PDAC) claims more than 90% of the patients diagnosed with the disease owing to its aggressive biology that is manifested by high rate of tumor recurrence. Aberrant upregulation in the transcriptional activity of proteins involved in self-renewal like Sox2, Oct4 and Nanog is instrumental in these recurrence phenomena. In cancer, Sox2 is aberrantly “turned-on” leading to activation of downstream genes those results in relapse of the tumor. Molecular mechanisms that regulate the activity of Sox2 in PDAC are not known. In the current study, we have studied the how glycosylation of Sox2 by O-GlcNAc transferase (OGT) can affect its transcriptional activity and thus regulate self-renewal in cancer.

Methods: RNA-Seq analysis of CRISPR-OGTi PDAC cells indicated a deregulation of differentiation and self-renewal pathways in PDAC. Pancreatic tumor burden following inhibition of OGT in vivo was done by using small molecule inhibitor, OSMI, on subcutaneous implantation of PDAC cells. Sox2 activity assay was performed by Dual Luciferase Reporter Assay kit.

Results: Our study shows for the first time that in PDAC, glycosylation of Sox2 by OGT stabilizes it in the nucleus. Site directed mutagenesis of this site (S246A) prevents this modification. We further show that inhibition of OGT delayed initiation of pancreatic tumors by inhibition of Sox2. We also show that targeting OGT in vivo with a small molecule-inhibitor OSMI, results in decreased tumor burden in PDAC.

Conclusion: Understanding this mechanism of SOX2 regulation by its glycosylation is expected to pave the way for development of novel therapy that has the potential to eradicate the cells responsible for tumor-recurrence.

Keywords: OGT, O-GlcNAc, Sox2, Pancreatic cancer, metabolism, self-renewal