Altaf Mohammed

DCAMKL-1 regulates epithelial-mesenchymal transition in human pancreatic cells through a miR-200a-dependent mechanism

Pancreatic cancer is an exceptionally aggressive disease in great need of more effective therapeutic options. Epithelial-mesenchymal transition (EMT) plays a key role in cancer invasion and metastasis, and there is a gain of stem cell properties during EMT. Here we report increased expression of the putative pancreatic stem cell marker DCAMKL-1 in an established KRAS transgenic mouse model of pancreatic cancer and in human pancreatic adenocarcinoma. Colocalization of DCAMKL-1 with vimentin, a marker of mesenchymal lineage, along with 14-3-3 σ was observed within premalignant PanIN lesions that arise in the mouse model. siRNA-mediated knockdown of DCAMKL-1 in human pancreatic cancer cells induced microRNA miR-200a, an EMT inhibitor, along with downregulation of EMT-associated transcription factors ZEB1, ZEB2, Snail, Slug, and Twist. Furthermore, DCAMKL-1 knockdown resulted in downregulation of c-Myc and KRAS through a let-7a microRNA-dependent mechanism, and downregulation of Notch-1 through a miR-144 microRNA-dependent mechanism. These findings illustrate direct regulatory links between DCAMKL-1, microRNAs, and EMT in pancreatic cancer. Moreover, they demonstrate a functional role for DCAMKL-1 in pancreatic cancer. Together, our results rationalize DCAMKL-1 as a therapeutic target for eradicating pancreatic cancers.

Prevention and treatment of pancreatic cancer by curcumin in combination with omega-3 fatty acids.

Pancreatic cancer BxPC-3 cells were exposed to curcumin, docosahexaenoic acid (DHA), or combinations of both and analyzed for proliferation and apoptosis. Pancreatic tumor xenografts were established by injecting BxPC-3 cells into each flank of nude mice. After the tumors reached a size of approximately 190–200 mm3, animals were fed diets with or without 2,000 ppm curcumin in 18% corn oil or 15% fish oil + 3% corn oil for 6 more wk before assessing the tumor volume and expression of inducible nitric oxide synthase (iNOS), cyclooxygeanse-2 (COX-2), 5-lipoxinase (5-LOX), and p21. A synergistic effect was observed on induction of apoptosis (approximately sixfold) and inhibition of cell proliferation (approximately 70%) when cells were treated with curcumin (5 μ M) together with the DHA (25 μ M). Mice fed fish oil and curcumin showed a significantly reduced tumor volume, 25% (P < 0.04) and 43% (P < 0.005), respectively, and importantly, a combination of curcumin and fish oil diet showed > 72% (P < 0.0001) tumor volume reduction. Expression and activity of iNOS, COX-2, and 5-LOX are downregulated, and p21 is upregulated in tumor xenograft fed curcumin combined with fish oil diet when compared to individual diets. The preceding results evidence for the first time that curcumin combined with omega-3 fatty acids provide synergistic pancreatic tumor inhibitory properties.

Role of lipoxins, resolvins, and other bioactive lipids in colon and pancreatic cancer

Unresolved inflammation, due to insufficient production of proresolving anti-inflammatory lipid mediators, can lead to an increased risk of tumorigenesis and tumor cell invasiveness. Various bioactive lipids, particularly those formed by cyclooxygenase (COX) and lipoxygenase (LOX) enzymes, have been well established as therapeutic targets for many epithelial cancers. Emerging studies suggest that there is a role for anti-inflammatory bioactive lipids and their mediators during the resolution phase of inflammation. These proresolving bioactive lipids, including lipoxins (LXs) and resolvins (RVs), have potent anti-inflammatory and anti-carcinogenic properties. The molecular signaling pathways controlling generation and degradation of the proresolving mediators LXs and RVs are now being elucidated, and the component molecules may serve as new targets for regulation of inflammation and inflammation-associated cancers like colon and pancreatic cancers. This review will highlight the recent advances in our understanding of how these bioactive lipids and proresolving mediators may function with various immune cells and cytokines in inhibiting tumor cell proliferation and progression and invasiveness of colon and pancreatic cancers.

The Epidermal Growth Factor Receptor Inhibitor Gefitinib Prevents the Progression of Pancreatic Lesions to Carcinoma in a Conditional LSL-KrasG12D/+ Transgenic Mouse Model

Pancreatic ductal adenocarcinoma (PDAC) is the most common pancreatic malignancy with a dismal prognosis. Developing novel strategies to prevent or delay pancreatic cancer is currently of intense interest. The chemopreventive efficacy of gefitinib, an epidermal growth factor receptor (EGFR) inhibitor, was evaluated against the progression of pancreatic intraepithelial neoplasms (PanIN) to PDAC in conditional LSL-KrasG12D/+ transgenic mice. LSL-KrasG12D/+ and p48Cre/+ mice were bred, and offspring of activated KrasG12D/+ were generated. Six-week-old male KrasG12D/+ (20 per group) and C57BL/6 wild-type (12 per group) mice were fed (AIN-76A) diets containing 0, 100, and 200 ppm of gefitinib for 35 weeks. At termination, pancreases were evaluated histopathologically for PanINs and PDAC, and various biomarkers were measured by immunohistochemistry, immunofluorescence, immunoblotting, and/or reverse transcription-PCR. Dietary gefitinib at 100 and 200 ppm significantly suppressed PDAC incidence by 77% and 100%, respectively (P < 0.0001) when compared with control diet. Importantly, a significant inhibition of carcinoma and a dose-dependent suppression of PanINs [PanIN-1, 37-62% (P < 0.002); PanIN-2, 38-41 (P < 0.001); and PanIN-3, 7-34% (P < 0.0141)] were observed in mice treated with gefitinib. Furthermore, mice treated with 100 and 200 ppm of gefitinib exhibited 67.6% to 77.3% of the pancreas to be free from ductal lesions. Also, gefitinib reduced EGFR, proliferating cell nuclear antigen, cyclin D1, C2GNT, RhoA, β-catenin, p38, phospho-extracellular signal–regulated kinase, caveolin-1, and mucin and increased cyclin B1 in the pancreatic lesions/PDAC. In summary, these results show that gefitinib can prevent the progression of pancreatic cancer precursor lesions to PDAC in a preclinical model. The present study highlights the promise of chemoprevention and the potential usefulness of EGFR inhibitors in individuals at high risk for pancreatic cancer. Cancer Prev Res; 3(11); 1417–26. ©2010 AACR.

β-Ionone inhibits colonic aberrant crypt foci formation in rats, suppresses cell growth, and induces retinoid X receptor-α in human colon cancer cells

β-Ionone, an end-ring analogue of β-carotenoid, which is a constituent of vegetables and fruits, has been analyzed for colon cancer chemoprevention and treatment. β-Ionone induced cell growth inhibition and apoptosis in human colon cancer HCT116 cell line. We tested the in vivo chemopreventive efficacy in rat colon carcinogenesis model using aberrant crypt foci (ACF) as endpoint marker. HCT116 cells treated with subtoxic concentrations of β-ionone resulted dose-dependent cell growth suppression with G1-S-phase growth arrest and significant induction of apoptosis. β-Ionone up-regulated expression of retinoid X receptor-α mRNA dose-dependently in HCT116 cells. To evaluate inhibitory properties of β-ionone on colonic ACF, 7-week-old male F344 rats were fed experimental diets containing 0%, 0.1%, or 0.2% β-ionone. After 1 week, rats received s.c. injections of azoxymethane, 15 mg/kg body weight, once weekly for 2 weeks. Rats were continued on respective experimental diets and sacrificed 8 weeks after the azoxymethane treatment. Colons were evaluated histopathologically for ACF. Administration of dietary 0.1% and 0.2% β-ionone significantly suppressed total colonic ACF formation up to 34% to 38% (P < 0.0002 to P < 0.0009), respectively, when compared with control group. Importantly, rats fed β-ionone showed >55% inhibition (P < 0.0001) of foci containing four or more aberrant crypts. Results from in vitro and in vivo bioassay clearly suggest that β-ionone could be further developed for prevention and treatment of colon cancer. [Mol Cancer Ther 2008;7(1):181–90]

Chemoprevention of Colon and Small Intestinal Tumorigenesis in APC Min/+ mice by Licofelone, A Novel Dual 5-LOX/COX Inhibitor: Potential Implications for Human Colon Cancer Prevention

Preclinical and clinical studies suggest that 5-lipoxygenase (5-LOX), such as COX-2, is a potential target for colon cancer inhibition and, in part, contributes to cardiovascular side effects associated with COX-2 inhibitors. Experiments were designed to assess the chemopreventive effects of a novel dual 5-LOX/COX inhibitor, licofelone {[6-(4-chlorophenyl)-2,2-dimethyl-7-phenyl-2,3-dihydro-1H-pyrrolizin-5-yl] acetic acid}, in APCMin/+ mouse intestinal tumorigenesis. Six-week-old male and female APCMin/+ mice (n = 10 per group) were fed with control American Institute of Nutrition-76A diet or diets containing 150 or 300 ppm licofelone for 14 weeks (∼100 days), and intestinal tumors were evaluated for tumor multiplicity and size. Licofelone significantly inhibited total intestinal tumor multiplicity and size in a dose-dependent manner (P < 0.0001; mean tumors for 0, 150, and 300 ppm: 48.8, 17, and 8, respectively, in male mice; and 34.3, 8.8, and 5.5, respectively, in female mice). Licofelone at high dose showed more than 83% (P < 0.0001) tumor inhibition in both genders of mice. One hundred and fifty and 300 ppm licofelone resulted in 86% to 97% inhibition of polyps having size greater than 2 mm. One hundred and fifty and 300 ppm licofelone caused more than 72% and 100% inhibition of colonic tumors, respectively. Importantly, in mice fed with licofelone, tumors showed significantly reduced proliferating cell nuclear antigen expression (70%, P < 0.0001), increased terminal deoxynucleotidyl transferase–mediated dUTP nick end labeling–positive cells (75%, P < 0.0001), and there was dose-dependent suppression of serum triglycerides (71%–83%, P < 0.0001), decreased inflammatory cytokines; and decreased COX and 5-LOX activities (57%–64%, P < 0.0001). Also, compared with 300 ppm celecoxib, 300 ppm licofelone provided better efficacy in suppressing tumor growth. These observations show that a novel dual 5-LOX/COX inhibitor dramatically suppresses small intestinal and colonic tumor formation in APCMin/+ mice. Cancer Prev Res; 4(12); 2015–26. ©2011 AACR.

Atorvastatin delays progression of pancreatic lesions to carcinoma by regulating PI3/AKT signaling in p48Cre/+ LSL-KrasG12D/+ mice.

Pancreatic cancer is the one of most common causes of cancer deaths and has the worst prognosis. Clinical observational studies suggest that statins may reduce the risk of pancreatic cancer. The chemopreventive efficacy of the statin atorvastatin (Lipitor®) and the role of the phosphatidyl‐inositol 3‐kinase (PI3/AKT) signaling pathway were evaluated for the progression of pancreatic intraepithelial neoplasms (PanINs) to pancreatic ductal adenocarcinoma (PDAC) in conditional p48Cre/+‐LSL‐KrasG12D/+ transgenic mice. Six‐week‐old male p48Cre/+‐LSL‐KrasG12D/+ (20/group) mice were fed AIN‐76A diets containing 0, 200 and 400 ppm atorvastatin for 35 weeks. At termination, pancreata were evaluated histopathologically for PanINs and PDAC, and for various PI3/AKT signaling markers, and inflammatory cytokines, by immunohistochemistry/immunohistoflourscence, ELISA, Western blotting and/or reverse transcription‐PCR methods. Control diet‐fed mice showed 85% incidence of PDAC; whereas, mice fed with atorvastatin showed PDAC incidence of 65 and 35%, respectively (p < 0.0001). Similarly, significant suppression of PanIN‐3 (22.6%) was observed in mice fed 400 ppm atorvastatin. Importantly, pancreata from atorvastatin‐treated mice were ∼68% free from ductal lesions. Furthermore, pancreas of mice administered with atorvastatin had significantly reduced expressions levels of PCNA, p2X7, p‐ERK, RhoA, cyclin D1, survivin, Akt, pAKT, β‐catenin, cyclin E, cdK2 and caveolin‐1. Also, atorvastatin‐treated mice had shown dose‐dependent suppression of inflammatory cytokines and a significant increase in tunnel‐positive cells, p21 and PARP expression levels in pancreas. Atorvastatin significantly delays the progression of PanIN‐1 and ‐2 lesions to PanIN‐3 and PDAC by modulating PI3/AKT signal molecules in a preclinical model, suggesting potential clinical benefits of statins for high‐risk pancreatic cancer patients.

Chemopreventive effects of Frondanol A5, a Cucumaria frondosa extract, against rat colon carcinogenesis and inhibition of human colon cancer cell growth.

Sea cucumber extracts have been widely used to treat individuals with inflammatory conditions in East Asia. The present study has been designed to test potential colon cancer–preventive properties of Frondanol A5, a glycolipid extract from the sea cucumber, Cucumaria frondosa, using in vivo and in vitro models of colon cancer. Chemopreventive efficacy of Frondanol A5 was evaluated on azoxymethane-induced rat colon carcinogenesis using colonic aberrant crypt foci (ACF) as efficacy marker. At 7 weeks of age, groups of rats (12 per group) were fed the AIN-76A diet, and ACFs were induced by azoxymethane (15 mg/kg body weight). Three days after azoxymethane treatment, rats were fed with the diets containing 0, 150, and 450 ppm of Frondanol A5 and continued on the diets for 8 weeks, at which time ACFs were evaluated. Expression levels of proliferating cell nuclear antigen and p21WAF1/CIP1 were determined in ACFs. Further, Frondanol A5 (10-120 μg/mL) was studied for its growth-inhibitory and apoptotic effects in the HCT-116 cell line. Dietary administration of 150 and 450 ppm of Frondanol A5 significantly suppressed azoxymethane-induced total colonic ACF formation, approximately 34% to 55% (P < 0.01 to P < 0.0001), and multicrypt aberrant foci (48-68.5%, P < 0.0001) in a dose-dependent manner. ACFs in rats treated with Frondanol A5 showed significant upregulation of p21WAF1/CIP1 and downregulation of proliferating cell nuclear antigen compared with control group. Frondanol A5 showed growth inhibition at S and G2-M phase with a decrease in Cdc25c and an increase in p21WAF1/CIP with significant apoptosis associated with H2AX phosphorylation and caspase-2 cleavage in HCT116 cells. Overall, Frondanol A5 exhibits potential chemopreventive properties for colon carcinogenesis, which suggests further development of this sea cucumber extract. Cancer Prev Res; 3(1); 82–91

Sea Cucumbers Metabolites as Potent Anti-Cancer Agents

Sea cucumbers and their extracts have gained immense popularity and interest among researchers and nutritionists due to their nutritive value, potential health benefits, and use in the treatment of chronic inflammatory diseases. Many areas of the world use sea cucumbers in traditional foods and folk medicine. Though the actual components and their specific functions still remain to be investigated, most sea cucumber extracts are being studied for their anti-inflammatory functions, immunostimulatory properties, and for cancer prevention and treatment. There is large scope for the discovery of additional bioactive, valuable compounds from this natural source. Sea cucumber extracts contain unique components, such as modified triterpene glycosides, sulfated polysaccharides, glycosphingolipids, and esterified phospholipids. Frondanol A5, an isopropyl alcohol/water extract of the enzymatically hydrolyzed epithelia of the edible North Atlantic sea cucumber, Cucumaria frondosa, contains monosulfated triterpenoid glycoside Frondoside A, the disulfated glycoside Frondoside B, the trisulfated glycoside Frondoside C, 12-methyltetradecanoic acid, eicosapentaenoic acid, and fucosylated chondroitin sulfate. We have extensively studied the efficacy of this extract in preventing colon cancer in rodent models. In this review, we discuss the anti-inflammatory, immunostimulatory, and anti-tumor properties of sea cucumber extracts.

Early detection and prevention of pancreatic cancer: Use of genetically engineered mouse models and advanced imaging technologies

Lack of early detection and effective interventions are major factors contributing to the poor prognosis and dismal survival rates of pancreatic cancer patients for more than sixty years. Detection of pancreatic cancer at an early stage might permit life-saving intervention. Clinical and preclinical diagnosis and evaluation of pancreatic cancers involve several imaging technologies including magnetic resonance imaging (MRI), Positron emission tomography (PET), Computed tomography (CT), Ultrasound (US), bioluminescent imaging and single photon emission computed tomography (SPECT). The advent of genetically engineered animal models that recapitulate the cellular and molecular pathology of human pancreatic intraepithelial neoplasia (PanINs) and pancreatic ductal adenocarcinoma (PDAC) has not yet yielded translational implications. Although the use of tumor xenografts to predict drug efficacy in patients has been disappointing, use of novel transgenic mice models should permit improved early detection and development of drug regimens through integration of appropriate imaging modalities. This review will consider issues that are unique to working with transgenic mouse models, such as the biology of genetically engineered mouse (GEM) models, stage- tumor-specific detection using imaging technologies, use of monoclonal antibodies, nanoparticles, and biomarkers, and development of chemopreventive and chemotherapeutic drugs for PDAC. These issues will be considered in the context of recently developed preclinical models of pancreatic cancer.