Abstract 1159: Targeting novel mucin synthesis pathway for pancreatic cancer treatment
Authors: Mohammed Altaf , Janakiram Naveena B. , Madka Venkateshwar , Kumar Gaurav , Edgar Scott , Pathuri Gopal , Bryant Taylor , Zhang Yuting , Gali Hariprasad , Zhao Yan Daniel , Lightfoot Stan , Rao Chinthalapally V. 
Published: July 2017

Pancreatic cancer (PC) is most fatal and is the fourth leading cause of cancer related deaths in USA with a least five year survival of &lt;7%. Although several overexpressed mucin subtypes (MUC1, MUC4, MUC5AC, and MUC16) that impede drug delivery to PC have been targeted with limited results, core enzymes involved in mucin biosynthesis have yet to be evaluated as potential targets. The core 2 β 1,6 N-acetylglucosaminyltransferase (GCNT3/C2GNT) plays a significant role in mucin glycan biosynthesis. We analyzed GCNT3 expression on 180 specimens from individuals with PC (90) or matched controls (90). Patients with low GCNT3 expression survived longer than patients with high GCNT3 expression (median survival: 17.5 vs. 10.5 months, p=0.036). We observed a significant increase in GCNT3 mRNA expression (103.16 folds; p&lt;0.0001) in correlation with increased mucins subtypes (p&lt;0.05) in the pancreatic tumors from genetically engineered mouse (GEM) compared with pancreata from wild-type mice, as determined by Next-generation Sequencing/RNAseq analysis. In in silico studies, blind docking simulations revealed that a novel drug talniflumate binds to GCNT3 with a better docking affinity of -8.3 kcal/mol. We synthesized talniflumate and determined quality/purity using NMR, HRMS, and HPLC for in vitro and in vivo studies. Pancreata from 6-week-old Kras GEM (N=6/group) treated with talniflumate showed a significant decrease in GCNT3 and mucin expression in PanIN lesions. In human PC MiaPaCa cell line, talniflumate reduced GCNT3 expression and the number of mucin-positive cells (38% p&lt;0.0001). Further, PC cells (BxPc3 and Panc1) were treated with talniflumate for 24 hrs for mucin disruption followed by radioactive 3H gemcitabine treatment for 2 hrs. The cells treated with talniflumate showed 40% (p&lt;0.03) and 50% (p&lt;0.025) increased 3H gemcitabine uptake in BxPc3 and Panc1 cells compared to respective controls.

GCNT3 CRISPR knock out PC cells and talniflumate treated PC cells showed a reduction in cell proliferation and significantly reduced spheroid formation (p&lt;0.05). In in vivo, we did not observe any overt toxicity upon talniflumate treatment as determined by liver enzyme toxicity and body weight gain (N=5 mice/group). BxPC3 cells implanted nude mice (N=5 mice/group) treated with talniflumate or GCNT3 siRNA showed a marked reduction in xenograft tumors compared with untreated controls. Both talniflumate and GCNT3 siRNA significantly inhibited xenograft tumor weight (48% p&lt;0.002 with siRNA, 63% p&lt;0.0001 with talniflumate) and tumor volume (75% p&lt;0.0001 with both siRNA and talniflumate) and GCNT3 enzyme activity (28% p&lt;0.03). Transcriptome analysis of xenograft tumors (N=3/group) treated with GCNT3 SiRNA or talniflumate showed reduced GCNT3 and top hits related to mucin expression. These results justify the use of talniflumate for mucin synthesis disruption, thereby enhancing the uptake of gemcitabine and thereby efficacy for PC treatment.

Citation Format: Altaf Mohammed, Naveena B. Janakiram, Venkateshwar Madka, Gaurav Kumar, Scott Edgar, Gopal Pathuri, Taylor Bryant, Yuting Zhang, Hariprasad Gali, Yan Daniel Zhao, Stan Lightfoot, Chinthalapally V. Rao. Targeting novel mucin synthesis pathway for pancreatic cancer treatment [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 1159. doi:10.1158/1538-7445.AM2017-1159