Abstract 977: Glycosylation of estrogen receptor alpha by N-acetylgalactosaminyltransferase 6 in breast cancer

• Published in: Cancer research (Chicago, Ill.) Ill.), 2018-07, Vol.78 (13_Supplement), p.977-977
• Main Authors: Deng, Boya, Tarhan, Yunus Emre, Ueda, Koji, Matsuo, Yo, Park, Jae-Hyun, Nakamura, Yusuke
• Format: Article
• Language: English
• ISSN: 0008-5472; 1538-7445
• DOI: 10.1158/1538-7445.AM2018-977

Alteration of protein O-glycosylation in various human cancers including breast cancer is well known, but molecular mechanisms of such aberrant modifications and their effects on cancer development have not been fully understood. We previously reported the critical roles of polypeptide N-acetylgalactosaminyltransferase 6 (GALNT6), which is upregulated in a great majority of breast cancers and is responsible for initiating mucin-type O-glycosylation. Suppression of GALNT6 expression by small interfering RNA to GALNT6 significantly enhanced cell-cell adhesion, induced mesenchymal-epithelial transition, and suppressed the growth of breast cancer cells. Here we further analyzed molecular functions of GALNT6 and found that GALNT6 could glycosylate an estrogen receptor alpha (ER-α) protein, a molecule playing a central role in proliferation of hormone-dependent breast cancer cells. We have used two breast cancer cell lines, T47D and MCF7, in which both the estrogen receptor and GALNT6 were highly expressed. Knockdown of GALNT6 expression by siRNA could significantly attenuate expression of ER-α at transcriptional and protein levels in these breast cancer cell lines in a condition with or without estradiol (P