Pancreatic cancer is an aggressive neoplasm with almost uniform lethality and a 5-year survival rate of 7%. Several overexpressed mucins that impede drug delivery to pancreatic tumors have been therapeutically targeted, but enzymes involved in mucin biosynthesis have yet to be preclinically evaluated as potential targets. We used survival data from human patients with pancreatic cancer, next-generation sequencing of genetically engineered Kras-driven mouse pancreatic tumors and human pancreatic cancer cells to identify the novel core mucin-synthesizing enzyme GCNT3 (core 2 b-1,6 N-acetylglucosaminyltransferase). In mouse pancreatic cancer tumors, GCNT3 upregulation (103-fold; P < 0.0001) was correlated with increased expression of mucins (5 to 87-fold; P < 0.04-0.0003). Aberrant GCNT3 expression was also associated with increased mucin production, aggressive tumorigenesis, and reduced patient survival, and CRISPR-mediated knockout of GCNT3 in pancreatic cancer cells reduced proliferation and spheroid formation. Using in silico small molecular docking simulation approaches, we identified talniflumate as a novel inhibitor that selectively binds to GCNT3. In particular, docking predictions suggested that three notable hydrogen bonds between talniflumate and GCNT3 contribute to a docking affinity of À8.3 kcal/mol. Furthermore, talniflumate alone and in combination with low-dose gefitinib reduced GCNT3 expression, leading to the disrupted production of mucins in vivo and in vitro. Collectively, our findings suggest that targeting mucin biosynthesis through GCNT3 may improve drug responsiveness, warranting further development and investigation in preclinical models of pancreatic tumorigenesis.

The role of the unique T-cell population, natural killer T (NKT) cells, which have similar functions to NK cells in pancreatic cancer (PC), is not yet evaluated. To address the regulatory roles of NKT cells on tumour progression through tumour-associated macrophages (TAM) and their production of microsomal prostaglandin E synthase-1 (mPGES-1) and 5-lipoxygenase (5-LOX) in (Kras)-driven pancreatic tumour (KPT) progression, we crossed CD1d mice deficient in both invariant and variant NKT cells with the Kras mice. Loss of NKT cells significantly increased pancreatic intraepithelial neoplasia (PanIN) lesions and also increased 5-LOX and mPGES-1 expression in M2-type macrophages and cancer stem-like cells in pancreatic tumours. Pharmacological inhibition of mPGES-1 and 5-LOX in M2 macrophages with specific inhibitor YS-121 in KPT-CD1d mice decreased PanIN lesions and suppressed tumour growth in association with elevated levels of active CD8a cells. Hence, NKT cells regulate PC by modulating TAMs (M2) through mPGES-1 and 5-LOX; and the absence of NKT cells leads to aggressive development of PC.

Colorectal cancer (CRC) is the second highest cause of cancer-related deaths. A successful strategy to improve chemopreventive efficacies is by down-regulating tumor polyamines and enhancing NK cell activities. Colonic carcinogenesis was induced by azoxymethane (AOM) in male F344 rats. Eight weeks after AOM treatment, animals were fed diets containing Rosuvastatin and difluromethylornithine (DFMO) individually and in combination for 40 weeks. Both agents showed significant suppression of adenocarcinoma multiplicity and incidence with no toxicity compared to untreated rats. Low-dose Rosuvastatin plus DFMO suppressed colon adenocarcinoma multiplicity by 76% compared to low-dose Rosuvastatin (29%) and DFMO (46%), suggesting additive efficacy. Furthermore, low-dose combination caused a delay in colonic adenocarcinoma progression. DFMO, Rosuvastatin and/or combinations significantly decreased polyamine content and increased intra-tumoral NK cells expressing perforin plus IFN-γ compared to untreated colon tumors. Further ex-vivo analysis of splenic NK cells exposed to DFMO, Rosuvastatin or combination resulted in an increase of NKs with perforin expression. This is the first report on Rosuvastatin alone or combination strategy using clinically relevant statin plus DFMO doses which shows a significant suppression of colon adenocarcinomas, and their potential in increasing functional NK cells. This strategy has potential for further testing in high risk individuals for colon cancer.

Estrogen Receptor (ER)-β signaling is associated positively in colon tumor progression, whereas down-regulation or loss of function of retinoid X receptor (RXR)-α occurs in colon tumors. The chemopreventive efficacies of the estrogen antagonist raloxifene and the selective RXR agonist bexarotene were tested individually and in combination, during promotion and progression stages of colon tumorigenesis. Colon tumors were induced in male F344 rats with azoxymethane and at early adenoma stage, groups of rats (36 or 45/group) were fed diets containing raloxifene (1.5 or 3 ppm), bexarotene (50 or 100 ppm), or their low dose combinations for 40 weeks. Raloxifene or bexarotene alone significantly suppressed colon adenocarcinoma formation in terms of multiplicities (mean ± SE): control, 3.59 ± 0.25; 1.5 ppm raloxifene, 2.51 ± 0.29 (p<0.004); 3 ppm raloxifene, 2.14 ± 0.28 (p<0. 0001); 50 ppm bexarotene, 2.25 ± 0.32 (p<0.001); 100 ppm bexarotene, 2.1 ± 0.27 (p<0.0001) and 1.5 ppm raloxifene + 50 ppm bexarotene, 1.57 ± 0.21 (p<0.0001). The low dose combination caused significant (56 %) inhibition of adenocarcinomas as compared with control diet fed rats. Tumors exposed to raloxifene, bexarotene and/or the combination showed significant suppression of proliferating cell nuclear antigen, cyclin D1 and β-catenin with an increased apoptotic cells (3-fold) and p21 expression (3.8-fold) as compared tumors of rats fed control diet. The combination of low doses of raloxifene and bexarotene significantly suppressed the progression of colonic adenomas to adenocarcinomas and may be useful for colon cancer prevention and/or treatment in high-risk individuals.

Sea cucumbers are a source of anti-bacterial, anti-inflammatory, and anti-cancer compounds. We show that sea cucumber extract Frondanol® A5 is capable of enhancing innate immune responses and inhibiting intestinal tumors in APCMin/+ mice. APCMin/+ mice were fed semi-purified diets containing 0, 250, or 500 ppm Frondanol®A5 for 14 weeks before we assessed intestinal tumor inhibition. Dietary Frondanol® A5 suppressed small intestinal polyp sizes and formation up to 30% (p<0.02) in males and up to 50% (p<0.01) in females. Importantly, 250 and 500 ppm Frondanol® A5 diet suppressed colon tumor multiplicities by 65% (p<0.007) and 75% (p<0.0001), compared with untreated male APCMin/+ mice. In female APCMin/+ mice, both dose levels of Frondanol® A5 suppressed colon tumor multiplicities up to 80% (p<0.0001). Isolated peritoneal macrophages from treated mice showed increased phagocytosis efficiency (Control 24% Vs treated 50%; p<0.01) and an increase in GILT mRNA expression, indicating increased innate immune responses by these cells in treated animals. Similarly, we observed an increase in GILT expression in treated tumors, compared with untreated tumors. Furthermore, an increase in GCSF cytokine, a decrease in inflammatory cytokines and marker 5-LOX, its regulator FLAP, proliferation (PCNA), and angiogenesis (VEGF) markers was observed in treatment groups. These data suggest that Frondanol® A5 decreased inflammatory angiogenic molecules and increased GILT expression and macrophage phagocytosis. These decreases may have improved the innate immune systems of the treated mice, thus aiding in inhibition of intestinal tumor formation. These results suggest that Frondanol® A5 exhibits significant chemopreventive potential against intestinal tumorigenesis.