Misty Brewer

Eflornithine (DFMO) Prevents Progression of Pancreatic Cancer by Modulating Ornithine Decarboxylase Signaling

Ornithine decarboxylase (ODC) is the key rate-limiting enzyme in the polyamine synthesis pathway and it is overexpressed in a variety of cancers. We found that polyamine synthesis and modulation of ODC signaling occurs at early stages of pancreatic precursor lesions and increases as the tumor progresses in Kras-activated p48Cre/+-LSL-KrasG12D/+ mice. Interest in use of the ODC inhibitor eflornithine (DFMO) as a cancer chemopreventive agent has increased in recent years since ODC was shown to be transactivated by the c-myc oncogene and to cooperate with the ras oncogene in malignant transformation of epithelial tissues. We tested the effects of DFMO on pancreatic intraepithelial neoplasias (PanIN) and their progression to pancreatic ductal adenocarcinoma (PDAC) in genetically engineered Kras mice. The KrasG12D/+ mice fed DFMO at 0.1% and 0.2% in the diet showed a significant inhibition (P < 0.0001) of PDAC incidence compared with mice fed control diet. Pancreatic tumor weights were decreased by 31% to 43% (P < 0.03–0.001) with both doses of DFMO. DFMO at 0.1% and 0.2% caused a significant suppression (27% and 31%; P < 0.02–0.004) of PanIN 3 lesions (carcinoma in situ). DFMO-treated pancreas exhibited modulated ODC pathway components along with decreased proliferation and increased expression of p21/p27 as compared with pancreatic tissues derived from mice fed control diet. In summary, our preclinical data indicate that DFMO has potential for chemoprevention of pancreatic cancer and should be evaluated in other PDAC models and in combination with other drugs in anticipation of future clinical trials. Cancer Prev Res; 7(12); 1198–209. ©2014 AACR.

Chemopreventive Efficacy of Raloxifene, Bexarotene, and Their Combination on the Progression of Chemically Induced Colon Adenomas to Adenocarcinomas in Rats

Estrogen receptor (ER)-β signaling is associated positively in colon tumor progression, whereas downregulation 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 per 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. Cancer Prev Res; 6(12); 1251–61. ©2013 AACR.

Adoptive transfer of regulatory T cells promotes intestinal tumorigenesis and is associated with decreased NK cells and IL‐22 binding protein

High number of regulatory T cells (Tregs), both circulating and at the tumor site, often indicates a poor prognosis in CRC patients possibly impairing natural killer (NK) cell function. To determine the role of Tregs in CRC development and their effects on NK cells, we created novel transgenic Rag‐Apc mice that lack T cells and develop spontaneous intestinal tumors, and we adoptively transferred Tregs or transiently depleted NK cells during initial stages of tumorigenesis. In 6‐weeks old Rag‐Apc mice containing microscopic intestinal tumors adoptive transfer of Tregs or transient NK cell depletion dramatically associated with an increase in intestinal tumor multiplicity and tumor size, with significantly decreased survival rates. Importantly, Treg transfer increased small intestinal polyp formation up to 65% (P < 0.0005) and increased colon tumors multiplicities by 84% (P < 0.0001) with a significant decrease in NK cells as compared to control mice. Similarly, in NK depleted mice, colon tumor multiplicities increased up to 40% and small intestinal polyp formation up to 60% (P < 0.0001). Treg transfer or NK cell transient depletion markedly increased interleukin (IL)‐22 systemically and the inflammatory signaling molecules P2X7R, and STAT3 in the tumors; and impaired production of the tumor suppressor interferon (IFN)‐γ systemically. Notably, IL‐22 binding protein (IL‐22 BP) was associated with NKs and a significant decrease was seen at the tumor site in mice adoptively transferred with Tregs or depleted of NK cells. Our results suggest that adoptive transfer of Tregs aggressively promote intestinal tumorigenesis by decreasing NK cell number and activity by modulating IL‐22 BP.

Mass profiling of serum to distinguish mice with pancreatic cancer induced by a transgenic Kras mutation

Mass spectrometry (MS) has the unique ability to profile, in an easily accessible body tissue (peripheral blood/serum,) the sizes and relative amounts of a wide variety of biomolecules in a single platform setting. Using electrospray ionization (ESI)‐MS, we distinguished individual serum from wild‐type control mice from serum of mice containing an oncogenic Kras mutation, which leads to development of pancreatic ductal adenocarcinoma (PDAC) similar to that observed in humans. Identification of differences in significant ESI‐MS sera mass peaks between Kras‐activated mice and control mice was performed using t tests and a “nested leave one out” cross‐validation procedure. Peak distributions in serum of control mice from mice with Kras‐mutant‐dependent PDAC were distinguished from those of pancreatic intraepithelial neoplasia (PanIN) lesions (p = 0.00024). In addition, Kras mutant mice with PDAC were distinguished from Kras mutant mice with PanIN alone (p = 0.0057). Test specificity, a measure of the false positives, was greater for the control vs. Kras mutated mice, and the test sensitivity, a measure of false negatives, was greater for the PDAC vs. PanIN containing mice. Receiver‐operating characteristic (ROC) curve discriminatory values were 0.85 for both comparisons. These studies indicate ESI‐MS serum mass profiling can detect physiological changes associated with pancreatic cancer initiation and development in a GEM (genetic engineered mouse) model that mimics pancreatic cancer development in humans. Such technology has the potential to aid in early detection of pancreatic cancer and in developing therapeutic drug interventions.

Abstract 1005: Targeting COX-LOX and EGFR pathways simultaneously by licofelone and gefitinib lead to complete blockade of progression of PanINs to pancreatic ductal adenocarcinoma

Proceedings: AACR 103rd Annual Meeting 2012‐‐ Mar 31‐Apr 4, 2012; Chicago, IL Pancreatic ductal adenocarcinoma (PDAC), a devastating disease with dismal prognosis (5-year survival rate of <5%), is the fourth leading cause of cancer deaths in the USA. Developing novel strategies to prevent or delay progression of pancreatic cancer is currently of intense interest. Clinically, COX-2 (93%), 5-LOX (90%) and EGRF (87%) are over-expressed in human PDAC. COX-2 & 5-LOX metabolites play a pivotal role in cell signaling and proliferation, and their release has been shown in response to EGF and growth stimuli. Both COX-2 & EGFR are known to synergistically activate oncogenic signaling. To target COX-2, 5-LOX and EGFR simultaneously, we tested the effects of licofelone, a novel dual 5-LOX-COX-2 inhibitor and gefitinib, an EGFR inhibitor individually and in combination on pancreatic intraepithelial neoplasms (PanINs) and their progression to PDAC in p48Cre/+-LSL-KrasG12D/+ mice. Six-week old male and female KrasG12D/+ (∼35/group) mice were fed (AIN-76A) diets containing 0, 250 ppm licofelone, 100 ppm gefitinib or combination of both for 38 weeks. Pancreata were collected, weighed, and evaluated histopathologically for PanINs and PDAC. To understand molecular mechanisms, we analyzed levels of proliferation, apoptosis, cell cycle and modification in cancer stem cell makers (DCAMKL-1 & CD133); COX-2, 5-LOX, PCNA, p21, p2X7, cyclin D1, β-catenin, EGFR, Cav-1, p38, C2GNT and mucin expressions by Radiomatic HPLC, IHC, IHF, Tunel, Western blotting, and/or RT-PCR methods. Results suggest that control diet fed mice showed 64 and 82% incidence of PDAC in female and male mice, respectively. Dietary licofelone and gefitinib significantly inhibited incidence of PDAC in both male (72 & 90%, respectively, p<0.0001) and female (90 & 85%, respectively, p<0.0001) mice. Most importantly, the combination drug treatment showed complete (100%, p<0.0001) inhibition of PDAC incidence in both genders of mice. Also, a significant suppression of PanIN 3 (56, 50 and 70% P<0.001) was observed in mice fed by licofelone, gefitinib and their combination, respectively. The pancreas of mice fed combination diets showed significantly reduced cancer stem-cells positive for DCAMKL-1 and CD133 (P<0.0001) and a significant inhibition of COX-2, 5-LOX, PCNA, cyclin D1, EGFR, p38, Cav-1 and β-catenin expression levels (p<0.05-0.0002); and increased apoptosis, when compared to the pancreatic cancer derived from control diet or individual drug fed mice. Importantly, mucin synthesis and C2GNT were significantly inhibited by gefitinib and combination but not licofelone, suggesting that EGFR activation is linked to pancreatic ductal mucin biosynthesis. In summary, targeting the 5-LOX/COX-2 and EGFR pathways simultaneously may provide synergistic and/or additive chemopreventive effects in complete suppression of PDAC. {Supported by NCI-CN-N01-53300}. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 1005. doi:1538-7445.AM2012-1005

Abstract 2969: Combinational Targeting of EGFR and ODC pathways by Gefitinib and DFMO lead to complete blockade of PanIN progression to pancreatic ductal adenocarcinoma

Proceedings: AACR Annual Meeting 2014; April 5-9, 2014; San Diego, CA Pancreatic cancer (PC) is a devastating disease with almost uniform lethality despite aggressive treatment (5-year survival rate of <6%). Developing novel strategies to prevent/delay/inhibit progression of PC is currently of intense interest. Epidermal growth factor receptor (EGFR) is over-expressed in ∼87% human pancreatic cancers and plays a pivotal role in tumor cell proliferation. An interaction between ornithine decarboxylase (ODC) overexpression and EGFR was suggested by the elevation of EGFR Tyr-K activity. Clinical and preclinical studies have clearly demonstrated chemopreventive potential of difloromethyl ornithine (DFMO), an ODC inhibitor. Higher doses of gefitinib (EGFR inhibitor) and DFMO has been associated with skin- and oto-toxicity respectively. Hence, to target EGFR and ODC simultaneously, we tested the effects of lower doses of gefitinib and DFMO individually and in combination on pancreatic intraepithelial neoplasms (PanINs) and their progression to pancreatic ductal adenocarcinoma (PDAC) in p48Cre/+-LSL-KrasG12D/+ transgenic mice. Six-week old male and female KrasG12D/+ (24-34/group) mice were fed (AIN-76A) diets containing 0%, 0.01% gefitinib, 0.1% DFMO or combination of both for 38 weeks. Pancreata were collected, weighed, and evaluated histopathologically for PanINs and PDAC. To understand molecular mechanisms, we analyzed levels of proliferation, apoptosis and cell cycle makers; PCNA, p21, β-catenin, Cav-1, Bcl-XL, c-MYC, cyclin E and pERK expressions by IHC, IHF, Western blotting, and/or RT-PCR methods. Results suggest that control diet fed mice showed 80 and 65% incidence of PDAC in male and female mice, respectively. Dietary gefitinib and DFMO significantly inhibited incidence of PDAC in both male (90 & 87%, respectively, p<0.0001) and female (84 & 75%, respectively, p<0.0001) mice. Most importantly, the combination drug treatment showed complete (100%, p<0.0001) inhibition of PDAC incidence in both genders of mice. Also, significant suppression of PanIN 3 (carcinoma in-situ) was observed in mice fed by gefitinib, DFMO and their combination. Importantly, ∼77% of the pancreas was free from lesions and carcinoma in the combination treatment compared to only 4 % in control and 39 and 23 % in gefitinib and DFMO fed mice respectively. The pancreas of mice fed combination diets showed a significant inhibition of PCNA, β-catenin, Cav-1, Bcl-XL, c-MYC, cyclin E and pERK expression levels (p<0.05-0.001); and increased p21 when compared to the pancreatic cancer derived from control diet or individual drug fed mice. In summary, targeting the EGFR and ODC pathways simultaneously may provide synergistic and/or additive chemopreventive effects in suppression of PC and has significant potential for undertaking clinical trials of pancreatic cancer chemoprevention. {Supported by NCI-CN-N01-53300}. Citation Format: Altaf Mohammed, Naveena B. Janakiram, Rebekah L. Ritchie, Laura Biddick, Misty Brewer, Stan Lightfoot, Vernon E. Steele, Chinthalapally V. Rao. Combinational Targeting of EGFR and ODC pathways by Gefitinib and DFMO lead to complete blockade of PanIN progression to pancreatic ductal adenocarcinoma. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 2969. doi:10.1158/1538-7445.AM2014-2969

Abstract 2145: Chemopreventive and immune-modulatory effects of the Cucumaria frondosa extract, Frondanol A5 in the APCMin/+ mice intestinal tumorigenesis

Proceedings: AACR Annual Meeting 2014; April 5-9, 2014; San Diego, CA Sea cucumbers have been used widely as a food source and for their health benefits, which include treatment of various chronic inflammatory conditions. We have shown previously that Cucumaria frondosa extract, Frondanol A5 inhibits azoxymethane -induced colonic precursor lesions in F344 rats. Experiments were designed to assess the chemopreventive efficacy of Frondanol A5, for suppression of intestinal tumorigenesis in male and female APCMin/+ mice. Six-week-old APCMin/+ mice were fed the modified AIN-76A diets containing 0, 250 or 500 ppm Frondanol A5 for 14 weeks. To understand molecular mechanisms, we analyzed levels of proliferation, inflammatory and angiogenesis makers; PCNA, inflammatory cytokines, 5-lipoxygenase (5-LOX), Five Lox Activating Protein (FLAP) and vascular endothelial growth factor (VEGF) expressions by IHC, IHF, and/or RT-PCR methods. To determine immuno-modulatory effects of Fondanol A5 on intestinal tumorigenesis, number of macrophages was evaluated in the blood, SI polyps and colon tumors by Giemsa staining, ex-vivo phagocytic assay was performed on the peritoneal macrophages isolated from the control and treated mice. Further, γ-interferon-inducible lysosomal thiolreductase (GILT) mRNA expression was analyzed in the peritoneal macrophages, SI polyps and colonic tumors. Dietary administration of 250 and 500 ppm of Frondanol A5 suppressed small intestinal polyp formation up to 28 % (p<0.02) in males and up to 50 % (p<0.01) in females; and significantly decreased polyp size in both genders. Importantly, 250 and 500 ppm Frondanol A5 diet suppressed colon tumors multiplicities by 65% (p<0.007) and 75% (p<0.0001) as compared to control diet fed male APCMin/+ mice. Similarly, in female APCMin/+ mice, dietary Frondanol A5 at both dose levels suppressed colon tumor multiplicities up to 80% (p<0.0001). Frondanol A5 showed significant colon tumor inhibitory dose-response effects in male APCMin/+ mice. Intestinal tumors of Frondanol A5-fed mice showed significantly reduced expression of PCNA, 5-LOX, its regulator molecule, FLAP and angiogenic marker VEGF. Frondanol A5-fed-mice showed suppression of serum inflammatory cytokines and increased expression of granulocyte-colony stimulating factor (G-CSF) by ELISA. Importantly, mice treated with Frondanol A5 diet showed enhanced phagocytic activity and increase in number of macrophages (Control 24% Vs treated 50%; p<0.01) and caused a significant increase in GILT mRNA expression, in both peritoneal macrophages as well as colonic tumors. These results suggest that Frondanol A5 exhibits significant chemopreventive potential in FAP model of SI and colon tumorigenesis. Frondanol A5 induced antitumor activities in part mediated through modulation of inflammatory molecules and stimulation of macrophage activity. Supported by NIH Grant N01-CN-53300 and R01CA094962. Citation Format: Naveena B. Janakiram, Altaf Mohammed, Misty Brewer, Peter D. Collin, Vernon E. Steele, Chinthalapally V. Rao. Chemopreventive and immune-modulatory effects of the Cucumaria frondosa extract, Frondanol A5 in the APCMin/+ mice intestinal tumorigenesis. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 2145. doi:10.1158/1538-7445.AM2014-2145

Abstract 186: Clinically relevant low dose combination of rosuvastatin and difluoromethylornithine provides effective chemopreventive efficacy against AOM-induced colon cancers in F344 rats .

Proceedings: AACR 104th Annual Meeting 2013; Apr 6-10, 2013; Washington, DC Preclinical and clinical studies suggest that statins and polyamine inhibitors suppress growth, invasion and progression of malignant colon tumors. Experiments were designed to evaluate the human clinical relevant doses of Rosuvastatin and Difluromethylornithine (DFMO), individually and in combination, on azoxymethane (AOM)-induced colon adenocarcinomas (AdCa) in male F344 rats. Eight weeks of age, rats (30-36/group) treated with AOM to induce the colonic tumors and nine weeks after the AOM treatment, groups of rats were fed AIN-76A diets containing Rosuvastatin (50 or 100 ppm), DFMO (500 or 1000 ppm), or their low dose combination for an additional 40 weeks. AOM-treated rats fed control diet showed AdCa multiplicity of 3.59 ± 0.48 (Mean ±SEM) and AdCa incidence of 96.6 %. 50 or 100 ppm Rosuvastatin significantly suppressed AdCa multiplicities (29%, p 52% (p<0.003) more inhibition of invasive AdCa multiplicity. As anticipated, DFMO at both doses significantly inhibited AdCa multiplicity (p<0.003 - p<0.0001) and incidence (p<0.05-0.001) as compared to control diet. The combination of low-dose Rosuvastatin plus low dose DFMO suppressed colon AdCa multiplicity by 76% (p<0.0001) as compared to low-dose Rosuvastatin (29%) and low-dose DFMO (46%), suggesting an additive effect. This low dose combination also resulted in delay of colonic AdCa progression, as revealed by the presence of a higher number of adenomas in the treated group as compared to the low adenoma/high AdCa occurrence in the control diet group. DFMO, Rosuvastatin and/or combinations caused significantly decreased expression of cyclin E, cdk2, cav-1, laminin 1β, and mutant p53 proteins, and increased expression of wild type p53, cdc25c and p21 compared to control tumors by Western immunoblotting and Immunohistochemistry. The inflammatory markers IL-6, stat3, and COX-2 and the proliferation markers β-catenin and cyclin D1 also were down-regulated significantly in tumors of rats fed low-dose combinations as compared to low doses of Rosuvastatin or DFMO alone. This first report on combination treatment using clinically relevant doses of statin plus DFMO shows significant suppression of colon AdCa. Further studies are warranted using low-dose combinations of Rosuvastatin and DFMO in individuals at high risk for colon cancer. (Supported by R01-CA-94962 & NCI-CN-N01-53300) Citation Format: Naveena B. Janakiram, Altaf Mohammed, Taylor Bryant, Yuting Zhang, Misty Brewer, Ashley Duff, Laura Biddick, Stan Lightfoot, Vernon Steele, Chinthalapally V. Rao. Clinically relevant low dose combination of rosuvastatin and difluoromethylornithine provides effective chemopreventive efficacy against AOM-induced colon cancers in F344 rats . [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 186. doi:10.1158/1538-7445.AM2013-186

Abstract 4392: Targeting HADC-2: Chemopreventive effect of OSU-HDAC42 on rat colon carcinogenesis and APCmin/+ Mice intestinal tumorigenesis.

Proceedings: AACR 104th Annual Meeting 2013; Apr 6-10, 2013; Washington, DC Epigenetic modulators particularly histone deacetylases (HDACs) are valid targets cancer for prevention and Therapy. Recent studies from our laboratory and others suggest that HDAC-2 over-expression is associated with colon tumor progression and potential target for colon cancer prevention. The present study explored the chemopreventive effects of novel HDAC-2 inhibitor, OSU-HDAC42, in a mouse model of familial adenomatous polyposis (FAP). We used a rat colon carcinogenesis model assay, inhibition of aberrant crypt foci (ACF) development, as measure of the dose-response and chemopreventive effects. Colonic ACF were induced by azoxymethane (AOM) (15 mg/kg BW once weekly for 2 weeks by s.c. injection at the age of 8 and 9 weeks). One week after AOM-treatment groups of rats were fed AIN-76A diet containing 0, 75, 150 and 300 ppm OSU-HDAC42 for eight-weeks, and then colonic ACF were evaluated. Six week-old male C57Bl/6J-APCmin/+ and wild type mice were fed AIN-76A diet containing 150 ppm OSU-HADC42 or 300 ppm SAHA for 80 days. At ∼120 days of age, all mice were killed, and the intestines were evaluated for polyps. Dietary administration of OSU-HDAC42 produced a dose-dependent inhibition of AOM-induced colonic ACF formation (by 13-50%, p 46%, p 26%, P≥0.05) in APCmin/+ mice. Whereas 300 ppm SAHA showed limited non-significant inhibition of intestinal polyp formation in APCmin/+ mice. Further, OSU-HDAC42 showed inhibition in small intestinal polyps size measuring 1-2-mm (P<0.001). Importantly, mice fed with 150ppm OSU-HDAC42 showed significant reduction in HDAC-2, PCNA, CyclinA, CDK2, CDC25C expression pattern and increased p53 expression levels. These observations demonstrate that novel HDAC inhibitor, OSU-HDAC42 potential chemopreventive against the chemically-induced and polyposis models of colon tumorigenesis. {This work is supported by NCI-N01-CN53300} Citation Format: Durgadevi Ravillah, Li Qian, Misty Brewer, Yuting Zhang, Laura Biddick, Venkateshwar Madka, Jagan M.R. Patlolla, Altaf Mohammed, Vernon Steele, Chintalapally V. Rao. Targeting HADC-2: Chemopreventive effect of OSU-HDAC42 on rat colon carcinogenesis and APCmin/+ Mice intestinal tumorigenesis. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 4392. doi:10.1158/1538-7445.AM2013-4392

Abstract A15: Chemopreventive efficacy of Phospho-Ibuprofen, Rosuvastatin and their combination on AOM-induced colon adenocarcinoma formation in F344 rats

Phospho-Ibuprofen (P-I) is a derivative of ibuprofen designed to reduce the traditional toxicities of non-steroidal anti-inflammatory drugs (NSAIDs). P-I is studied for its anti-inflammatory and cancer properties in arthritis, breast cancer models and showed better gastrointestinal safety compared to NSAIDs. Statins has been effective for cholesterol lowering and protecting cardiovascular diseases in addition to its antineoplastic effects in preclinical and clinical observations. A promising strategy to enhance the cancer preventive efficacy of statins and NSAIDs in combination is to produce synergy without any unwanted side effects. Hence, experiments were designed to evaluate the chemopreventive efficacies of P-I and Rosuvastatin, which were administered individually and in combination on azoxymethane (AOM)-induced colon cancer formation in F344 rats. Male F344 rats (~30-45 animals/group) were fed AIN-76A diet and colon tumors were induced with two weekly doses of AOM (15 mg/kg body wt). Eight weeks after the AOM-treatment, groups of rats were fed AIN-76A diets containing ibuprofen (200 ppm), P-I (360 and 720 ppm), Rosuvastatin (50 and 100 ppm), or their low dose combinations for 40 weeks. Colonic tumors were evaluated histopathologically as invasive and noninvasive adenocarcinomas (AdCa) and modulating effects of P-I, and Rosuvastatin and combinations were studied on markers of colon tumor cell proliferation and apoptosis. Results: Administration of P-I at 720 ppm significantly suppressed AOM-induced colon non-invasive and invasive AdCa formation (multiplicity (Mean±SEM): Non-invasive AdCa: Untreated, 1.37±0.22; P-I treated, 0.70±0.14 (p 0.05) effect on AOM-induced AdCa multiplicity or incidence. Proliferation markers, proliferating cell nuclear antigen (PCNA), Cdk2, Cdc25C and Cav1, in tumors of rats exposed to P-I, Rosuvastatin and/or combinations were significantly suppressed. Also, colonic tumors from rats fed combination diet showed significant suppression of Erk and pErk protein expression as compared to colon tumors from rats fed the control diet. This is the first report on the combination using low-dose P-I and Rosuvastatin, which significantly suppressed the colon adenocarcinomas. Our results suggest that low-dose P-I with Rosuvastatin might potentially be a useful combination for colon cancer prevention/treatment in high risk individuals. (Supported by NCI-CN-N01-53300). Citation Format: Naveena B. Janakiram, Altaf Mohammed, Yuting Zhang, Misty Brewer, Taylor Bryant, Laura Biddick, Stan Lightfoot, Vernon E. Steele, Chinthalapally V. Rao. Chemopreventive efficacy of Phospho-Ibuprofen, Rosuvastatin and their combination on AOM-induced colon adenocarcinoma formation in F344 rats. [abstract]. In: Proceedings of the Twelfth Annual AACR International Conference on Frontiers in Cancer Prevention Research; 2013 Oct 27-30; National Harbor, MD. Philadelphia (PA): AACR; Can Prev Res 2013;6(11 Suppl): Abstract nr A15.