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J Biol Chem. 2017 Sep 29;292(39):16351-16359. doi: 10.1074/jbc.M117.783936. Epub 2017 Aug 23.

The glycosyltransferase GnT-III activates Notch signaling and drives stem cell expansion to promote the growth and invasion of ovarian cancer.

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From the Medical Microbiology and Immunology Department, Menofiya University, Cairo 11795, Egypt.
the Department of Biology, Ouachita Baptist University, Arkadelphia, Arkansas 71998, and.
the Departments of Biochemistry and Molecular Biology and.
Obstetrics and Gynecology, University of Arkansas for Medical Sciences, Little Rock, Arkansas 72205.
the Departments of Biochemistry and Molecular Biology and


Glycosylation changes associated with cellular transformation can facilitate the growth and progression of tumors. Previously we discovered that the gene Mgat3 encoding the glycosyltransferase GnT-III is elevated in epithelial ovarian carcinomas (EOCs) and leads to the production of abnormal truncated N-linked glycan structures instead of the typical bisected forms. In this study, we are interested in discovering how these abnormal glycans impact the growth and progression of ovarian cancer. We have discovered using stable shRNA gene suppression that GnT-III expression controls the expansion of side-population cells, also known as cancer stem cells. More specifically, we found that GnT-III expression regulates the levels and activation of the heavily glycosylated Notch receptor involved in normal and malignant development. Suppression of GnT-III in EOC cell lines and primary tumor-derived cells resulted in an inhibition of Notch signaling that was more potent than pharmacologic blockage of Notch activation via γ-secretase inhibition. The inhibition resulted from the redirection of the Notch receptor to the lysosome, a novel mechanism. These findings demonstrate a new role for bisecting glycosylation in the control of Notch transport and demonstrate the therapeutic potential of inhibiting GnT-III as a treatment for controlling EOC growth and recurrence.


N-linked glycosylation; Notch pathway; cancer; glycosylation; ovarian cancer

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