Prevention of azoxymethane-induced colon cancer by combination of low doses of atorvastatin, aspirin, and celecoxib in F 344 rats

Lipid-lowering drugs and cancer: an updated perspective

Statins and non-statin medications used for the management of dyslipidemia have been shown to possess antitumor properties. Since the use of these drugs has steadily increased over the past decades, more knowledge is required about their relationship with cancer. Lipid-lowering agents are heterogeneous compounds; therefore, it remains to be revealed whether anticancer potential is a class effect or related to them all. Here, we reviewed the literature on the influence of lipid-lowering medications on various types of cancer during development or metastasis. We also elaborated on the underlying mechanisms associated with the anticancer effects of antihyperlipidemic agents by linking the reported in vivo and in vitro studies.

A Contemporary Review on the Critical Role of Nonsteroidal Anti-inflammatory Agents in Colorectal Cancer Therapy

Nonsteroidal Anti-Inflammatory Drugs (NSAIDs) are widely recognized as effective pain relievers and function by inhibiting the cyclooxygenase enzyme (COXs). Moreover, they have been found to participate in various cellular processes through different signaling pathways, such as WNT, MAPK, NF-κB, and PI3K/AKT/mTOR. This makes them potential candidates for chemoprevention of several malignancies, particularly colorectal cancer (CRC). However, the use of NSAIDs in cancer prevention and treatment is a complex issue due to their adverse effects and gastrointestinal toxicity. Therefore, it is crucial to explore combination therapies that can minimize side effects while maximizing synergistic effects with other agents and to evaluate the success rate of such approaches in both pre-clinical and clinical studies. In this review, we aim to provide an overview of the effects of NSAIDs in the prevention and treatment of CRC. We will focus on elucidating the possible mechanisms of action of these drugs, the signaling pathways involved in CRC, and the potential synergistic effects when combined with other therapeutic agents.

Microbiota-derived tryptophan catabolites mediate the chemopreventive effects of statins on colorectal cancer

Epidemiological studies have indicated an association between statin use and reduced incidence of colorectal cancer (CRC), and work in preclinical models has demonstrated a potential chemopreventive effect. Statins are also associated with reduced dysbiosis in the gut microbiome, yet the role of the gut microbiome in the protective effect of statins in CRC is unclear. Here we validated the chemopreventive role of statins by retrospectively analysing a cohort of patients who underwent colonoscopies. This was confirmed in preclinical models and patient cohorts, and we found that reduced tumour burden was partly due to statin modulation of the gut microbiota. Specifically, the gut commensal Lactobacillus reuteri was increased as a result of increased microbial tryptophan availability in the gut after atorvastatin treatment. Our in vivo studies further revealed that L. reuteri administration suppressed colorectal tumorigenesis via the tryptophan catabolite, indole-3-lactic acid (ILA). ILA exerted anti-tumorigenic effects by downregulating the IL-17 signalling pathway. This microbial metabolite inhibited T helper 17 cell differentiation by targeting the nuclear receptor, RAR-related orphan receptor γt (RORγt). Together, our study provides insights into an anti-cancer mechanism driven by statin use and suggests that interventions with L. reuteri or ILA could complement chemoprevention strategies for CRC.

Non-steroidal anti-inflammatory drugs and biomarkers: A new paradigm in colorectal cancer

Colorectal cancer is a sporadic, hereditary, or familial based disease in its origin, caused due to diverse set of mutations in large intestinal epithelial cells. Colorectal cancer (CRC) is a common and deadly disease that accounts for the 4^th worldwide highly variable malignancy. For the early detection of CRC, the most common predictive biomarker found endogenously are KRAS and ctDNA/cfDNA along with SEPT9 methylated DNA. Early detection and screening for CRC are necessary and multiple methods can be employed to screen and perform early diagnosis of CRC. Colonoscopy, an invasive method is most prevalent for diagnosing CRC or confirming the positive result as compared to other screening methods whereas several non-invasive techniques such as molecular analysis of breath, urine, blood, and stool can also be performed for early detection. Interestingly, widely used medicines known as non-steroidal anti-inflammatory drugs (NSAIDs) to reduce pain and inflammation have reported chemopreventive impact on gastrointestinal malignancies, especially CRC in several epidemiological and preclinical types of research. NSAID acts by inhibiting two cyclooxygenase enzymes, thereby preventing the synthesis of prostaglandins (PGs) and causing NSAID-induced apoptosis and growth inhibition in CRC cells. This review paper majorly focuses on the diversity of natural and synthetic biomarkers and various techniques for the early detection of CRC. An approach toward current advancement in CRC detection techniques and the role of NSAIDs in CRC chemoprevention has been explored systematically. Several prominent governing mechanisms of the anti-cancer effects of NSAIDs and their synergistic effect with statins for an effective chemopreventive measure have also been discussed in this review paper.

Therapeutic Potential of 6-Gingerol in Prevention of Colon Cancer Induced by Azoxymethane through the Modulation of Antioxidant Potential and Inflammation

A polyphenolic component of ginger, 6-gingerol, is widely reported to possess antioxidant, anti-inflammatory and anticancer activities. In the current study, it was aimed to investigate the anticancer effects of 6-gingerol (6-Gin) on azoxymethane (AOM)-induced colon cancer in rats. The results reveal that 6-Gin treatment significantly improves the antioxidant status disturbed by AOM intoxication. The 6-Gin treatment animal group showed enhanced activity of catalase (CAT) (46.6 ± 6.4 vs. 23.3 ± 4.3 U/mg protein), superoxide dismutase (SOD) (81.3 ± 7.6 vs. 60.4 ± 3.5 U/mg protein) and glutathione-S-transferase (GST) (90.3 ± 9.4 vs. 53.8 ± 10 mU/mg protein) (p < 0.05) as compared to the disease control group. Furthermore, the results reveal that AOM significantly enhances the inflammatory response and 6-gingerol potentially attenuates this response, estimated by markers, such as tumor necrosis factor-α (TNF-α) (1346 ± 67 vs. 1023 ± 58 pg/g), C-reactive protein (CRP) (1.12 ± 0.08 vs. 0.92 ± 0.7 ng/mL) and interleukin-6 (IL-6) (945 ± 67 vs. 653 ± 33 pg/g). In addition, the lipid peroxidation estimated in terms of malondialdehyde (MDA) provoked by AOM exposure is significantly reduced by 6-gingerol treatment (167 ± 7.5 vs. 128.3 nmol/g). Furthermore, 6-gingerol significantly maintains the colon tissue architecture disturbed by the AOM treatment. Loss of tumor suppressor protein, phosphatase and tensin homolog (PTEN) expression was noticed in the AOM treated group, whereas in the animals treated with 6-gingerol, the positivity of PTEN expression was high. In conclusion, the current findings advocate the health-promoting effects of 6-gingerol on colon cancer, which might be due to its antioxidant and anti-inflammatory potential.

Enabling the drug combination of celecoxib through a spherical co-agglomeration strategy with controllable and stable drug content and good powder properties

Combining celecoxib with other chemopreventive drugs is a promising method of chemoprevention for cancer, especially for colorectal cancer. However, the traditional drug combination approaches are restricted with high-cost apparatus, complex and numerous unit operations. This work aims to develop an efficient spherical co-agglomeration strategy for celecoxib in combination with lovastatin, which can achieve drug combination in a single crystallization unit. The ternary solvent system was determined based on molecular simulation, and then a stable spherical agglomeration process was developed through the design of molar fraction of anti-solvent (MFA) and stirring rate to produce spherical agglomerates with high sphericity (84.2-89.9 %) and narrow size distribution. On this basis, celecoxib-benzoic acid spherical co-agglomerates were designed to form a complete spherical co-agglomeration strategy, which includes solvent system selection, spherical agglomeration and spherical co-agglomeration. Finally, celecoxib-lovastatin spherical co-agglomerates with synergistic efficacy were successfully produced by this strategy, with controllable and stable drug content (fluctuation < 2.7 %), good powder properties, and improved tabletability.

Systems-level biomarkers identification and drug repositioning in colorectal cancer

Colorectal cancer (CRC) is the most commonly diagnosed fatal cancer in both women and men worldwide. CRC ranked second in mortality and third in incidence in 2020. It is difficult to diagnose CRC at an early stage as there are no clinical symptoms. Despite advances in molecular biology, only a limited number of biomarkers have been translated into routine clinical practice to predict risk, prognosis and response to treatment. In the last decades, systems biology approaches at the omics level have gained importance. Over the years, several biomarkers for CRC have been discovered in terms of disease diagnosis and prognosis. On the other hand, a few drugs are being developed and used in clinics for the treatment of CRC. However, the development of new drugs is very costly and time-consuming as the research and development takes about 10 years and more than $1 billion. Therefore, drug repositioning (DR) could save time and money by establishing new indications for existing drugs. In this review, we aim to provide an overview of biomarkers for the diagnosis and prognosis of CRC from the systems biology perspective and insights into DR approaches for the prevention or treatment of CRC.

Animal Models of Colorectal Cancer: From Spontaneous to Genetically Engineered Models and Their Applications

Colorectal cancer is one of the most common gastrointestinal malignancies in humans, affecting approximately 1.8 million people worldwide. This disease has a major social impact and high treatment costs. Animal models allow us to understand and follow the colon cancer progression; thus, in vivo studies are essential to improve and discover new ways of prevention and treatment. Dietary natural products have been under investigation for better and natural prevention, envisioning to show their potential. This manuscript intends to provide the readers a review of rodent colorectal cancer models available in the literature, highlighting their advantages and disadvantages, as well as their potential in the evaluation of several drugs and natural compounds’ effects on colorectal cancer.

Dysplastic Aberrant Crypt Foci: Biomarkers of Early Colorectal Neoplasia and Response to Preventive Intervention

The discovery of aberrant crypt foci (ACF) more than three decades ago not only enhanced our understanding of how colorectal tumors form, but provided new opportunities to detect lesions prior to adenoma development and intervene in the colorectal carcinogenesis process even earlier. Because not all ACF progress to neoplasia, it is important to stratify these lesions based on the presence of dysplasia and establish early detection methods and interventions that specifically target dysplastic ACF (microadenomas). Significant progress has been made in characterizing the morphology and genetics of dysplastic ACF in both preclinical models and humans. Image-based methods have been established and new techniques that utilize bioactivatable probes and capture histologic abnormalities in vivo are emerging for lesion detection. Successful identification of agents that target dysplastic ACF holds great promise for intervening even earlier in the carcinogenesis process to maximize tumor inhibition. Future preclinical and clinical prevention studies should give significant attention to assessing the utility of dysplastic ACF as the earliest identifiable biomarker of colorectal neoplasia and response to therapy.See all articles in this Special Collection Honoring Paul F. Engstrom, MD, Champion of Cancer Prevention.

Aspirin suppresses chemoresistance and enhances antitumor activity of 5-Fu in 5-Fu-resistant colorectal cancer by abolishing 5-Fu-induced NF-κB activation

Chemoresistance to 5-fluorouracil (5-Fu)-based chemotherapy is a leading obstacle in achieving effective treatment for colorectal cancer (CRC). Typically, NF-κB activation induced by the chemotherapeutics themselves is an important cause resulting in chemoresistance. Specifically, NF-κB activation can inhibit tumor cell apoptosis and induce chemoresistance. Drugs that can prevent NF-κB activation induced by chemotherapeutics are urgently needed to overcome chemoresistance. Obviously, aspirin is one of these agents, which has been demonstrated to possess antitumor activities and as an inhibitor of NF-κB. The current study aimed to investigate whether aspirin was able to overcome the chemoresistance to 5-Fu in CRC, together with the potential synergistic mechanisms. Our results suggested that aspirin remarkably potentiated the inhibitory effect of 5-Fu on the growth and invasion of resistant cells in vitro. In vivo, aspirin markedly enhanced the antitumor activity of 5-Fu in suppressing tumor growth and metastasis, and down-regulating the expression of NF-κB-regulated genes in the 5-Fu-resistant cells. Obviously, aspirin completely eradicated the 5-Fu-induced NF-κB activation, without inducing pronounced adverse effects. Taken together, findings in this study suggest that aspirin can reverse chemoresistance and potentiate the antitumor effect of 5-Fu, which is achieved through abolishing the 5-Fu-induced NF-κB activation, suggesting that aspirin may be a promising adjuvant therapeutic agent for CRC.

Intermittent Dosing Regimens of Aspirin and Naproxen Inhibit Azoxymethane-Induced Colon Adenoma Progression to Adenocarcinoma and Invasive Carcinoma

Chronic use of aspirin and related drugs to reduce cancer risk is limited by unwanted side effects. Thus, we assessed the efficacy associated with different dosing regimens of aspirin and naproxen. Azoxymethane (AOM)-rat colon cancer model was used to establish the pharmacodynamic efficacy of aspirin and naproxen under different dosing regimens. Colon tumors were induced in rats (36/group) by two weekly doses of AOM. At the early adenoma stage, rats were fed diets containing aspirin (700 and 1,400 ppm) or naproxen (200 and 400 ppm), either continuously, 1 week on/1 week off, or 3 weeks on/3 weeks off, or aspirin (2,800 ppm) 3 weeks on/3 weeks off. All rats were euthanized 48 weeks after AOM treatment and assessed for efficacy and biomarkers in tumor tissues. Administration of aspirin and naproxen produced no overt toxicities. Administration of different treatment regimens of both agents had significant inhibitory effects with clear dose-response effects. Aspirin suppressed colon adenocarcinoma multiplicity (both invasive and noninvasive) by 41% (P < 0.003) to 72% (P < 0.0001) and invasive colon adenocarcinomas by 67%-91% (P < 0.0001), depending on the treatment regimen. Naproxen doses of 200 and 400 ppm inhibited invasive adenocarcinoma multiplicity by 53%-88% (P < 0.0001), depending on the dosing regimen. Colonic tumor biomarker analysis revealed that proliferation (proliferating cell nuclear antigen and p21), apoptosis (p53 and Caspase-3), and proinflammatory mediators (IL1β and prostaglandin E2) were significantly correlated with the tumor inhibitory effects of aspirin and naproxen. Overall, our results suggest that intermittent dosing regimens with aspirin or naproxen demonstrated significant efficacy on the progression of adenomas to adenocarcinomas, without gastrointestinal toxicities.

Antitumor effects of curcumin: A lipid perspective

Lipid metabolism plays an important role in cancer development due to the necessities of rapidly dividing cells to increase structural, energetic, and biosynthetic demands for cell proliferation. Basically, obesity, type 2 diabetes, and other related diseases, and cancer are associated with a common hyperactivated "lipogenic state." Recent evidence suggests that metabolic reprogramming and overproduction of enzymes involved in the synthesis of fatty acids are the new hallmarks of cancer, which occur in an early phase of tumorigenesis. As the first evidence to confirm dysregulated lipid metabolism in cancer cells, the overexpression of fatty acid synthase (FAS) was observed in breast cancer patients and demonstrated the role of FAS in cancer. Other enzymes of fatty acid synthesis have recently been found to be dysregulated in cancer, including ATP-dependent citrate lyase and acetyl-CoA carboxylase, which further underscores the connection of these metabolic pathways with cancer cell survival and proliferation. The degree of overexpression of lipogenic enzymes and elevated lipid utilization in tumors is closely associated with cancer progression. The question that arises is whether the progression of cancer can be suppressed, or at least decelerated, by modulating gene expression related to fatty acid metabolism. Curcumin, due to its effects on the regulation of lipogenic enzymes, might be able to suppress, or even cause regression of tumor growth. This review discusses recent evidence concerning the important role of lipogenic enzymes in the metabolism of cancer cells and whether the inhibitory effects of curcumin on lipogenic enzymes is therapeutically efficacious.

PPARδ Mediates the Effect of Dietary Fat in Promoting Colorectal Cancer Metastasis

The nuclear hormone receptor peroxisome proliferator-activated receptor delta (PPARδ) is a ligand-dependent transcription factor involved in fatty acid metabolism, obesity, wound healing, inflammation, and cancer. Although PPARδ has been shown to promote intestinal adenoma formation and growth, the molecular mechanisms underlying the contribution of PPARδ to colorectal cancer remain unclear. Here, we demonstrate that activation of PPARδ induces expansion of colonic cancer stem cells (CSC) and promotes colorectal cancer liver metastasis by binding to the Nanog promoter and enhancing Nanog expression. Moreover, PPARδ mediated the effect of a high-fat diet in promoting liver metastasis and induction of colonic CSC expansion. Our findings uncover a novel role of dietary fats in colorectal cancer metastasis and reveal novel mechanisms underlying PPARδ-mediated induction of CSCs and those responsible for the contribution of dietary fats to colorectal cancer progression. These findings may provide a rationale for developing PPARδ antagonists to therapeutically target CSCs in colorectal cancer. SIGNIFICANCE: These findings show that PPARδ contributes to colorectal cancer metastasis by expanding the CSC population, indicating that antagonists that target PPARδ may be beneficial in treating colorectal cancer.

The Combined Use of Phenothiazines and Statins Strongly Affects Doxorubicin-Resistance, Apoptosis, and Cox-2 Activity in Colon Cancer Cells

Since none of the multidrug resistance (MDR) modulators tested so far found their way into clinic, a novel approach to overcome the MDR of cancer cells has been proposed. The combined use of two MDR modulators of dissimilar mechanisms of action was suggested to benefit from the synergy between them. The effect of three phenothiazine derivatives that were used as single agents and in combination with simvastatin on cell growth, apoptosis induction, activity, and expression of cyclooxygenase-2 (COX-2) in doxorubicin-resistant colon cancer cells (LoVo/Dx) was investigated. Treatment of LoVo/Dx cells by phenothiazine derivatives combined with simvastatin resulted in an increase of doxorubicin cytotoxicity and its intracellular accumulation as compared to the treatment with phenothiazine derivatives that were used as single agents. Similarly, LoVo/Dx cells treated with two-component mixture of modulators showed the reduced expression of ABCB1 (P-glycoprotein) transporter and COX-2 enzyme, both on mRNA and protein level. Reduced expression of anti-apoptotic Bcl-2 protein and increased expression of pro-apoptotic Bax were also detected. Additionally, COX-2 activity was diminished, and caspase-3 activity was increased to a higher extent by phenothiazine derivative:simvastatin mixtures than by phenothiazine derivatives themselves. Therefore, the introduction of simvastatin strengthened the anti-MDR, anti-inflammatory, and pro-apoptotic properties of phenothiazines in LoVo/Dx cells.

Combination therapy with atorvastatin and celecoxib delays tumor formation in a Fanconi anemia mouse model

BACKGROUND

Fanconi anemia is an inherited bone marrow failure disorder associated with a high incidence of leukemia and solid tumors. Currently, no interventions to prevent or delay the formation of solid tumors are available.

PROCEDURE

Two of the most important hallmarks of Fanconi anemia are inflammation and oxidative stress. In this study, we administrated the antioxidant atorvastatin and the anti-inflammatory drug celecoxib to cohorts of Fancd2^-/- /Trp53^+/- mice, a model of Fanconi anemia. Treatment started at weaning and continued until the mice developed a palpable mass or suffered from >20% weight loss. Tumor samples and selected tissues were subjected to histopathological examination. χ² test was performed to analyze tumor incidence, and Kaplan-Meier survival curves were evaluated with log-rank test. In addition, a small cohort of mice was monitored for the safety of the drugs.

RESULTS

The combined oral administration of both drugs significantly delayed tumor onset in Fancd2^-/- /Trp53^+/- mice. Specifically, the treatment delayed the onset of ovarian tumors in Fancd2^-/- /Trp53^+/- mice and increased the mean ovarian tumor-free survival time by 17%, whereas this combinatorial drug regimen did not have a significant effect on other tumor types. In addition, no detrimental effects on hematopoiesis from the drug treatment were observed during a 12-month safety monitoring.

CONCLUSIONS

The data presented here suggest that a combination of atorvastatin and celecoxib may be a good candidate for chemoprevention in Fanconi anemia.

Aspirin alone and combined with a statin suppresses eicosanoid formation in human colon tissue

Eicosanoids, including prostaglandins (PGs) and thromboxanes, are broadly bioactive lipid mediators and increase colon tumorigenesis possibly through chronic inflammatory mechanisms. Epidemiological and experimental data suggest that acetylsalicylic acid (ASA) helps prevent colorectal cancer (CRC), possibly through cyclooxygenase (COX)-mediated suppression of eicosanoid, particularly PGE2, formation. Recent studies suggest that statins prevent CRC and improve survival after diagnosis. We identified patients on ASA and/or statin treatment undergoing routine colonoscopy and measured eicosanoid levels in colonic mucosa with targeted metabolomics technology (LC-MS/MS). ASA-treated individuals (n = 27) had significantly lower tissue eicosanoid levels of most COX-derived metabolites than untreated individuals (n = 31). In contrast, COX-derived lipid metabolites tended to be higher in patients with statin treatment (n = 7) as compared with those not receiving statins (n = 24). This effect was not discernible in subjects treated with ASA and statins (n = 11): Individuals treated with both drugs showed a pronounced suppression of COX-derived eicosanoids in colon tissue, even compared with subjects treated with ASA alone. Our data from a routine clinical setting support the hypothesis that ASA and statins could inhibit CRC development via lipid mediator modification. Further studies should directly investigate the effect of dual ASA and statin treatment on colon tumorigenesis in humans.

Synergistic chemopreventive effects of nobiletin and atorvastatin on colon carcinogenesis

Different cancer chemopreventive agents may act synergistically and their combination may produce enhanced protective effects against carcinogenesis than each individual agent alone. Herein, we investigated the chemopreventive effects of nobiletin (NBT, a citrus polymethoxyflavone) and atorvastatin (ATST, a lipid-lowering drug) in colon cancer cells/macrophages and an azoxymethane (AOM)-induced colon carcinogenesis rat model. The results demonstrated that co-treatments of NBT/ATST produced enhanced growth inhibitory and anti-inflammatory effects on the colon cancer cells and macrophages, respectively. Isobologram analysis confirmed that these interactions between NBT and ATST were synergistic. NBT/ATST co-treatment also synergistically induced extensive cell cycle arrest and apoptosis in colon cancer cells. Oral administration of NBT (0.1%, w/w in diet) or ATST (0.04%, w/w in diet) significantly decreased colonic tumor incidence and multiplicity in AOM-treated rats. Most importantly, co-treatment of NBT/ATST at their half doses (0.05% NBT + 0.02% ATST, w/w in diet) resulted in even stronger inhibitory effects on colonic tumor incidence and multiplicity than did NBT or ATST alone at higher doses. Statistical analysis confirmed that the enhanced chemopreventive activities against colon carcinogenesis in rats by the NBT/ATST combination were highly synergistic. Our results further demonstrated that NBT/ATST co-treatment profoundly modulated key cellular signaling regulators associated with inflammation, cell proliferation, cell cycle progression, apoptosis, angiogenesis and metastasis in the colon of AOM-treated rats. In conclusion, for the first time, our results demonstrated a strong synergy in inhibiting colon carcinogenesis produced by the co-treatment of NBT and ATST, which provided a scientific basis for using NBT in combination with ATST for colon cancer chemoprevention in humans.

Microfluidic assembly of a nano-in-micro dual drug delivery platform composed of halloysite nanotubes and a pH-responsive polymer for colon cancer therapy

Harsh conditions of the gastrointestinal tract hinder the oral delivery of many drugs. Developing oral drug delivery systems based on commercially available materials is becoming more challenging due to the demand for simultaneously delivering physicochemically different drugs for treating complex diseases. A novel architecture, namely nanotube-in-microsphere, was developed as a drug delivery platform by encapsulating halloysite nanotubes (HNTs) in a pH-responsive hydroxypropyl methylcellulose acetate succinate polymer using microfluidics. HNTs were selected as orally acceptable clay mineral and their lumen was enlarged by selective acid etching. Model drugs (atorvastatin and celecoxib) with different physicochemical properties and synergistic effect on colon cancer prevention and inhibition were simultaneously incorporated into the microspheres at a precise ratio, with atorvastatin and celecoxib being loaded in the HNTs and polymer matrix, respectively. The microspheres showed spherical shape, narrow particle size distribution and pH-responsive dissolution behavior. This nanotube/pH-responsive polymer composite protected the loaded drugs from premature release at pH⩽6.5, but allowed their fast release and enhanced the drug permeability, and the inhibition of colon cancer cell proliferation at pH 7.4. Overall, the nano-in-micro drug delivery composite fabricated by microfluidics is a promising and flexible platform for the delivery of multiple drugs for combination therapy.

STATEMENT OF SIGNIFICANCE

Halloysite nanotubes (HNTs) are attracting increasing attention for drug delivery applications. However, conventional HNTs-based oral drug delivery systems are lack of the capability to precisely control the drug release at a desired site in the gastrointestinal tract. In this study, a nanotube-in-microsphere drug delivery platform is developed by encapsulating HNTs in a pH-responsive polymer using microfluidics. Drugs with different physicochemical properties and synergistic effect on colon cancer therapy were simultaneously incorporated in the microspheres. The prepared microspheres prevented the premature release of the loaded drugs after exposure to the harsh conditions of the gastrointestinal tract, but allowed their simultaneously fast release, and enhanced the drug permeability and the inhibition of colon cancer cell proliferation in response to the colon pH.

Statin use and the risk of colorectal adenoma: A meta-analysis

BACKGROUND

Although statin use has been reported to reduce the risk of colorectal cancer beyond its cholesterol-lowering effects, the benefit of statins against colorectal adenoma has not been fully clarified. We aimed to investigate the association between statin use and the risk of colorectal adenoma.

METHODS

We conducted a systematic literature search on MEDLINE, EMBASE, and the Cochrane Library using the primary keywords "adenoma," "polyp," "colorectal," "colon," "rectal," "rectum," "neoplasia," "neoplasm," "statin," "3-hydroxy-3-methylglutaryl-coenzyme A," and "HMG-CoA." Studies were included if they evaluated the association between statin use and adenoma and reported relative risks (RRs) or odds ratios or provided data for estimation. Pooled estimates were calculated using the random-effects model.

RESULTS

Six studies including 13 239 patients were analyzed. The median proportion of patients with any adenoma was 29.7% (range, 20.9-38.4%) in patients taking statins and 31.2% (range, 19.6-63.4%) in patients not taking statins across included studies. The median proportion of patients with advanced adenoma in those taking statins was 7.7% (range, 3.1-27.2%), whereas that in patients not taking statins was 11.3% (range, 3.5-32.4%). On meta-analysis, statin use did not significantly affect the risk of any adenoma (pooled RR = 0.901; 95% confidence interval [CI], 0.735-1.104); however, it was associated with a lower risk of advanced adenoma (pooled RR = 0.833; 95% CI, 0.750-0.925).

CONCLUSIONS

Statin use seems to be associated with a reduced risk of advanced adenoma, but not any adenoma. Statins may prevent neoplastic progression of adenomas rather than the development of adenomas.

Traditional serrated adenomas and serrated carcinomas in carcinogen-treated rats

AIMS

A recent review of archived sections from early experiments in rats showed neoplasias exhibiting serrated configurations. The aim was to assess the frequency of serrated neoplasias in the colon and small intestine of carcinogen-treated rats.

METHODS

While reviewing archival sections from early experiments in Sprague-Dawley (SD) and Fisher-344 (F-344) rats, we recently detected colonic and intestinal traditional serrated adenomas (displaying serrated or microtubular patterns) and serrated carcinomas. SD rats were injected 1,2-dimethylhydrazine (DMH) for 27 weeks whereas F-344 rats were fed with a pyrolysate (GLU-1) for 24 months. Filed sections from 358 colonic and small intestinal neoplasias were re-evaluated.

RESULTS

DMH-treated SD rats had 215 colonic neoplasias (1.4% were serrated adenomas, 7.9% microtubular adenomas, 2.8% serrated carcinomas and 2.8% microtubular carcinomas). GLU1-treated F-344 rats had 53 colonic neoplasias (1.9% were serrated adenomas and 20.8% microtubular adenomas), and 89 small intestinal neoplasias (1.1% were serrated adenomas, 42.7% microtubular adenomas and 6.7%, microtubular carcinomas).

CONCLUSIONS

DMH/SD-rats develop serrated and microtubular adenomas and carcinomas in the colon, whereas GLU1/F-344 rats develop microtubular adenomas in the colon and microtubular adenomas and carcinomas in the small intestine. The two rat-settings emerge as suitable models to study the molecular attributes of serrated and microtubular neoplasias under the standard conditions of the laboratory. This study is the first showing that a substantial number of serrated and particularly microtubular adenomas and carcinomas develop in the colon and small intestine of experimental rats. Importantly, serrated and microtubular neoplasias in rats recreate the histology of duodenal and colonic traditional serrated neoplasias in human beings.

Important molecular genetic markers of colorectal cancer

Colorectal cancer (CRC) ranks third in the incidences of cancer morbidity and mortality worldwide. CRC is rather heterogeneous with regard to molecular genetic characteristics and pathogenic pathways. A wide spectrum of biomarkers is used for molecular subtype determination, prognosis, and estimation of sensitivity to different drugs in practice. These biomarkers can include germline and somatic mutations, chromosomal aberrations, genomic abnormalities, gene expression alterations at mRNA or protein level and changes in DNA methylation status. In the present review we discuss the most important and well-studied CRC biomarkers, and their potential clinical significance and current approaches to molecular classification of colorectal tumors.

Exploiting the critical perioperative period to improve long-term cancer outcomes

Evidence suggests that the perioperative period and the excision of the primary tumour can promote the development of metastases—the main cause of cancer-related mortality. This Review first presents the assertion that the perioperative timeframe is pivotal in determining long-term cancer outcomes, disproportionally to its short duration (days to weeks). We then analyse the various aspects of surgery, and their consequent paracrine and neuroendocrine responses, which could facilitate the metastatic process by directly affecting malignant tissues, and/or through indirect pathways, such as immunological perturbations. We address the influences of surgery-related anxiety and stress, nutritional status, anaesthetics and analgesics, hypothermia, blood transfusion, tissue damage, and levels of sex hormones, and point at some as probable deleterious factors. Through understanding these processes and reviewing empirical evidence, we provide suggestions for potential new perioperative approaches and interventions aimed at attenuating deleterious processes and ultimately improving treatment outcomes. Specifically, we highlight excess perioperative release of catecholamines and prostaglandins as key deleterious mediators of surgery, and we recommend blockade of these responses during the perioperative period, as well as other low-risk, low-cost interventions. The measures described in this Review could transform the perioperative timeframe from a prominent facilitator of metastatic progression, to a window of opportunity for arresting and/or eliminating residual disease, potentially improving long-term survival rates in patients with cancer.

Inhibition of IL-6 expression in LNCaP prostate cancer cells by a combination of atorvastatin and celecoxib

In the present study, we investigated the effect of a combination of atorvastatin and celecoxib on the formation of interleukin (IL)-6, a cytokine that is increased during the progression of LNCaP tumors from androgen dependence to androgen independence. Culturing LNCaP cells in androgen‑depleted (AD) medium increased the levels of IL-6 and survivin, and treatment of the cells in AD medium with a combination of atorvastatin and celecoxib strongly inhibited the increase in IL-6 and survivin which is one of the downstream targets of the IL-6 signaling pathway. Addition of recombinant IL-6 partially abrogated the combined effect of atorvastatin and celecoxib on apoptosis in LNCaP cells cultured in AD medium. In SCID mice, we found that the levels of IL-6 and survivin expression were increased when LNCaP tumors became androgen-independent. Treatment of the mice with atorvastatin or celecoxib alone caused decrease in the levels of IL-6 and survivin as LNCaP tumors became androgen-independent, but treatment of the mice with a combination of celecoxib and atorvastatin resulted in a much stronger inhibition in the increase in IL-6 and survivin expression. Our results indicate that decreases in IL-6 and survivin levels by atorvastatin and celecoxib administration are associated with increased apoptosis in LNCaP cells treated with this drug combination. Our in vivo studies indicate that the inhibitory effect of a combination of atorvastatin and celecoxib on the progression of androgen-dependent LNCaP xenograft tumors to androgen independence is associated with inhibition of the increase in IL-6 and survivin that occurs when androgen-dependent LNCaP prostate tumors become androgen-independent.

Multitargeted low-dose GLAD combination chemoprevention: a novel and promising approach to combat colon carcinogenesis

Preclinical studies have shown that gefitinib, licofelone, atorvastatin, and α-difluoromethylornithine (GLAD) are promising colon cancer chemopreventive agents. Because low-dose combination regimens can offer potential additive or synergistic effects without toxicity, GLAD combination was tested for toxicity and chemopreventive efficacy for suppression of intestinal tumorigenesis in adenomatous polyposis coli (APC)(Min/+) mice. Six-week-old wild-type and APC(Min/+) mice were fed modified American Institute of Nutrition 76A diets with or without GLAD (25 + 50 + 50 + 500 ppm) for 14 weeks. Dietary GLAD caused no signs of toxicity based on organ pathology and liver enzyme profiles. GLAD feeding strongly inhibited (80-83%, P < .0001) total intestinal tumor multiplicity and size in APC(Min/+) mice (means ± SEM tumors for control vs GLAD were 67.1 ± 5.4 vs. 11.3 ± 1.1 in males and 72.3 ± 8.9 vs 14.5 ± 2.8 in females). Mice fed GLAD had >95% fewer polyps with sizes of >2 mm compared with control mice and showed 75% and 85% inhibition of colonic tumors in males and females, respectively. Molecular analyses of polyps suggested that GLAD exerts efficacy by inhibiting cell proliferation, inducing apoptosis, decreasing β-catenin and caveolin-1 levels, increasing caspase-3 cleavage and p21, and modulating expression profile of inflammatory cytokines. These observations demonstrate that GLAD, a novel cocktail of chemopreventive agents at very low doses, suppresses intestinal tumorigenesis in APC(Min/+) mice with no toxicity. This novel strategy to prevent colorectal cancer is an important step in developing agents with high efficacy without unwanted side effects.

Statins and colorectal cancer

The 3-hydroxy-3-methylglutaryl-coenzyme A reductase inhibitors, more commonly referred to as statins, comprise a family of lipid-lowering drugs that are prescribed on a global scale on account of their proven safety and efficacy in reducing mortality from cardiovascular disease. Beyond their potent pharmacologic inhibition of cholesterol biosynthesis, statins appear to have pleiotropic effects, including modulation of cell growth, apoptosis, and inflammation. Through modulation of these pathways, statins have the potential to influence a wide range of disease processes, including cancer. Much attention has focused on the association between statins and colorectal cancer, raising the prospect that these well-tolerated compounds could form the basis of future chemopreventive strategies. Herein, we review the epidemiologic, clinical, and preclinical data relevant to statins and colorectal neoplasia, and discuss the current status and future potential of statins as chemopreventive agents.

COX-2 active agents in the chemoprevention of colorectal cancer

Chemopreventive strategies for colorectal cancer (CRC) have been extensively studied to prevent the recurrence of adenomas and/or delay their development in the gastrointestinal tract. The non-steroidal anti-inflammatory drugs (NSAIDs) and selective cyclooxygenase (COX)-2 inhibitors have been proven as promising and the most attractive candidates for CRC clinical chemoprevention. The preventive efficacy of these agents is supported by a large number of animal and epidemiological studies which have clearly demonstrated that NSAID consumption prevents adenoma formation and decreases the incidence of, and mortality from CRC. On the basis of these studies, aspirin chemoprevention may be effective in preventing CRC within the general population, while aspirin and celecoxib may be effective in preventing adenomas in patients after polypectomy. Nevertheless, the consumption of NSAID and COX-2 inhibitors is not toxic free. Well-known serious adverse events to the gastrointestinal, renal and cardiovascular systems have been reported. These reports have led to some promising studies related to the use of lower doses and in combination with other chemopreventive agents and shown efficacy. In the intriguing jigsaw puzzle of cancer prevention, we now have a definite positive answer for the basic question "if", but several other parts of the equation-proper patient selection, the ultimate drug, optimal dosage and duration are still missing.

Lipoxygenase and Cyclooxygenase Pathways and Colorectal Cancer Prevention

Colorectal cancer is one of the commonest malignancies in both men and women. In spite of significant progress in screening and in surgical and therapeutic interventions, colorectal cancer (CRC) is still a major public health problem. Accumulating evidence suggests that targeting inflammatory pathways may provide protection against the development of CRC. Eicosanoids derived from the enzymes cyclooxygenase (COX) and lipoxygenase (LOX) may contribute to CRC carcinogenesis. Approaches for targeting COX-1 and COX-2 with traditional nonsteroidal anti-inflammatory agents or targeting COX-2 with specific inhibitors are highly successful at the preclinical and clinical levels; however, large-scale clinical applicability of these agents is limited owing to unwanted side effects. Emerging studies suggests that 5-LOX-derived leukotrienes may contribute to colon tumor development and risk of thrombotic events. Thus, developing drugs that target both 5-LOX and COX-2 may provide a safer strategy. In this review, we discuss evidence for the involvement of 5-LOX in colon tumor development and targeting 5-LOX and COX-2 with synthetic and naturally occurring agents for CRC prevention.

Atorvastatin inhibits pancreatic carcinogenesis and increases survival in LSL-KrasG12D-LSL-Trp53R172H-Pdx1-Cre mice

There are several studies supporting the role of HMG-CoA reductase inhibitors such as atorvastatin against carcinogenesis, in which inhibiting the generation of prenyl intermediates involved in protein prenylation plays the crucial role. Mutation of Kras gene is the most common genetic alteration in pancreatic cancer and the Ras protein requires prenylation for its membrane localization and activity. In the present study, the effectiveness of atorvastatin against pancreatic carcinogenesis and its effect on protein prenylation were determined using the LSL-KrasG12D-LSL-Trp53R172H-Pdx1-Cre mouse model (called Pankras/p53 mice). Five-week-old Pankras/p53 mice were fed either an AIN93M diet or a diet supplemented with 100 ppm atorvastatin. Kaplan-Meier survival analysis with Log-Rank test revealed a significant increase in survival in mice fed 100 ppm atorvastatin (171.9 ± 6.2 d) compared to the control mice (144.9 ± 8.4 d, P < 0.05). Histologic and immunohistochemical analysis showed that atorvastatin treatment resulted in a significant reduction in tumor volume and Ki-67-labeled cell proliferation. Mechanistic studies on primary pancreatic tumors and the cultured murine pancreatic carcinoma cells revealed that atorvastatin inhibited prenylation in several key proteins, including Kras protein and its activities, and similar effect was observed in pancreatic carcinoma cells treated with farnesyltransferase inhibitor R115777. Microarray assay on the global gene expression profile demonstrated that a total of 132 genes were significantly modulated by atorvastatin; and Waf1p21, cyp51A1, and soluble epoxide hydrolase were crucial atorvastatin-targeted genes which involve in inflammation and carcinogenesis. This study indicates that atorvastatin has the potential to serve as a chemopreventive agent against pancreatic carcinogenesis.

Statin use is associated with a reduced incidence of colorectal cancer: a colonoscopy-controlled case-control study

BACKGROUND

The aetiology of colorectal cancer (CRC) remains elusive in the majority of cases. There is experimental evidence to show that HMG-CoA reductase inhibitors (statins) may inhibit proliferation and induce cause apoptosis in CRC cells and although some clinical studies have suggested that statins may protect against the development of CRC, this has not been a consistent finding. Therefore we have examined any potential protective effects of statins by comparing statin use in patients with colorectal cancer against a control group.

METHODS

This was a case-control study examining statin use in symptomatic patients attending for diagnostic colonoscopy. Statin use was compared between patients with CRC and a control group, who had all had normal colonoscopy. Structured interviews and clinical records notes were used to determine drug exposure. Logistic regression was used to compare statin exposure and correct for confounding factors.

RESULTS

There was a significant inverse association between previous statin use and a diagnosis of CRC (OR = 0.43 (95% confidence interval 0.25 - 0.80), p<0.01). This inverse association was stronger with higher statin doses (OR = 0.19 (0.07 - 0.47), p<0.01) and greater duration of statin use (statin use >years: OR = 0.18 (0.06 - 0.55), p<0.01).

CONCLUSIONS

Statins use was associated with a protective effect against the development of CRC. This effect is associated with a significant dose and duration response. These findings need to be repeated in other observational studies before an interventional study can be considered.

Celecoxib inhibits growth of human autosomal dominant polycystic kidney cyst-lining epithelial cells through the VEGF/Raf/MAPK/ERK signaling pathway

Autosomal dominant polycystic kidney disease (ADPKD) is a progressive chronic kidney disease. To date there are no effective medicines to halt development and growth of cysts. In the present study, we explored novel effects of celecoxib (CXB), a COX-2 specific inhibitor, on primary cultures of human ADPKD cyst-lining epithelial cells. Primary cultures of ADPKD cyst-lining epithelial cells were obtained from five patients. Effects of CXB were measured by various assays to detect BrdU incorporation, apoptosis and proliferation in vitro. Additionally, effects of CXB on kidney weight, the cyst index, the fibrosis index, blood urea nitrogen (BUN), serum creatinine (SCr), serum 6-keto-PGF-1α, serum thromboxane-2 (TXB2) and renal PCNA expression were assessed in Han:SPRD rat, a well-characterized rodent model of PKD. CXB inhibited proliferation of ADPKD cyst-lining epithelial cells, blocked the release of VEGF from the cells and induced extensive apoptosis in a time- and dose-dependent manner. Moreover, CXB up-regulated the cell cycle negative regulator p21^CIP/WAF1 and the cell cycle positive regulator Cyclin A, blocked ERK1/2 phosphorylation, induced apoptotic factors (Bax and caspase-3) and reduced Bcl-2. Furthermore, CXB inhibited the expression of VEGFR-2 and Raf-1 in ADPKD cyst-lining epithelial cells. CXB markedly reduced the cyst index, the fibrosis index, leukocyte infiltration, BUN, SCr, serum 6-keto-PGF-1α, TXB2 and renal PCNA expression in Han:SPRD rat. We demonstrated for the first time that CXB could suppress renal cyst-lining growth both in vitro and in vivo in Han:SPRD rat. CXB can inhibit proliferation, suppress cell cycle progression, and induce apoptosis in ADPKD cyst-lining epithelial cells through the inhibition of the VEGF/VEGFR-2/Raf-1/MAPK/ERK signaling pathway.

Statins and the Risk of Hepatocellular Carcinoma in Patients With Hepatitis B Virus Infection

Purpose

Statins have potential protective effects against cancers, but no studies have focused on patients with chronic hepatitis B virus (HBV) infection. The purpose of this study was to investigate the association between the use of statins in HBV-infected patients and the risk of hepatocellular carcinoma (HCC).

Patients and Methods

We conducted a population-based cohort study from the Taiwan National Health Insurance Research Database. A total of 33,413 HBV-infected patients were included as the study cohort. Each patient was individually tracked from 1997 to 2008 to identify incident cases of HCC since 1999. Subsequent use of statin, other lipid-lowering agents, aspirin, and angiotensin-converting enzyme inhibitors was identified. Cox proportional hazards regression was used to calculate the hazard ratios (HRs) and 95% CIs for the association between the use of statins and the occurrence of HCC in the HBV-infected cohort.

Results

There were 1,021 HCCs in the HBV cohort during the follow-up period of 328,946 person-years; the overall incidence rate was 310.4 HCCs per 100,000 person-years. There was a dose-response relationship between statin use and the risk of HCC in the HBV cohort. The adjusted HRs were 0.66 (95% CI, 0.44 to 0.99), 0.41 (95% CI, 0.27 to 0.61), and 0.34 (95% CI, 0.18 to 0.67) for statin use of 28 to 90, 91 to 365, and more than 365 cumulative defined daily doses (cDDDs), respectively, relative to no statin use (< 28 cDDDs).

Conclusion

Statin use may reduce the risk for HCC in HBV-infected patients in a dose-dependent manner. Further mechanistic research is needed.

Chemoprevention of mouse lung and colon tumors by suberoylanilide hydroxamic acid and atorvastatin

Atorvastatin and suberoylanilide hydroxamic acid (SAHA) were evaluated for chemoprevention of mouse lung tumors. In Experiment 1, lung tumors were induced by vinyl carbamate in strain A/J mice followed by 500 mg/kg SAHA, 60 or 180 mg/kg atorvastatin, and combinations containing SAHA and atorvastatin administered in their diet. SAHA and both combinations, but not atorvastatin, decreased the multiplicity of lung tumors, including large adenomas and adenocarcinomas with the combinations demonstrating the greatest efficacy. In Experiment 2, lung tumors were induced by 4-(methylnitrosoamino)-1-(3-pyridyl)-1-butanol in strain A/J mice followed by 180 mg/kg atorvastatin, 500 mg/kg SAHA, or both drugs administered in the diet. SAHA and the combination of both drugs, but not atorvastatin alone, decreased the multiplicity of lung tumors and large tumors, with the combination demonstrating greater efficacy. In Experiment 3, lung tumors were induced by 1,2-dimethylhydrazine in Swiss-Webster mice followed by 160 mg/kg atorvastatin, 400 mg/kg SAHA, or a combination of both drugs administered in the diet. SAHA and the combination, but not atorvastatin, decreased the multiplicity of lung tumors with the combination demonstrating greater efficacy. The multiplicity of colon tumors was decreased by SAHA, atorvastatin, and the combination, without any significant difference in their efficacy. mRNA expression analysis of lung tumor bearing mice suggested that the enhanced chemopreventive activity of the combination is related to atorvastatin modulation of DNA repair, SAHA modulation of angiogenesis, and both drugs modulating invasion and metastasis pathways. Atorvastatin demonstrated chemoprevention activity as indicated by the enhancement of the efficacy of SAHA to prevent mouse lung tumors.

Pharmacological actions of statins: a critical appraisal in the management of cancer

Statins, among the most commonly prescribed drugs worldwide, are cholesterol-lowering agents used to manage and prevent cardiovascular and coronary heart diseases. Recently, a multifaceted action in different physiological and pathological conditions has been also proposed for statins, beyond anti-inflammation and neuroprotection. Statins have been shown to act through cholesterol-dependent and -independent mechanisms and are able to affect several tissue functions and modulate specific signal transduction pathways that could account for statin pleiotropic effects. Typically, statins are prescribed in middle-aged or elderly patients in a therapeutic regimen covering a long life span during which metabolic processes, aging, and concomitant novel diseases, including cancer, could occur. In this context, safety, toxicity, interaction with other drugs, and the state of health have to be taken into account in subjects treated with statins. Some evidence has shown a dichotomous effect of statins with either cancer-inhibiting or -promoting effects. To date, clinical trials failed to demonstrate a reduced cancer occurrence in statin users and no sufficient data are available to define the long-term effects of statin use over a period of 10 years. Moreover, results from clinical trials performed to evaluate the therapeutic efficacy of statins in cancer did not suggest statin use as chemotherapeutic or adjuvant agents. Here, we reviewed the pharmacology of the statins, providing a comprehensive update of the current knowledge of their effects on tissues, biological processes, and pathological conditions, and we dissected the disappointing evidence on the possible future use of statin-based drugs in cancer therapy.

Aspirin in the chemoprevention of colorectal neoplasia: an overview

Considerable evidence supports the effectiveness of aspirin for chemoprevention of colorectal cancer (CRC) in addition to its well-established benefits in the prevention of vascular disease. Epidemiologic studies have consistently observed an inverse association between aspirin use and risk of CRC. A recent pooled analysis of a long-term posttrial follow-up of nearly 14,000 patients from four randomized, cardiovascular disease prevention trials showed that daily aspirin treatment for about five years was associated with a 34% reduction in 20-year CRC mortality. A separate metaanalysis of nearly 3,000 patients with a history of colorectal adenoma or cancer in four randomized adenoma prevention trials showed that aspirin reduced the occurrence of advanced adenomas by 28% and any adenoma by 17%. Aspirin has also been shown to be beneficial in a clinical trial of patients with Lynch syndrome, a hereditary CRC syndrome; in those treated with aspirin for at least two years, there was a 50% or more reduction in the risk of CRC commencing five years after randomization and after aspirin had been discontinued. A few observational studies have shown an increase in survival among patients with CRC who use aspirin. Taken together, these findings strengthen the case for consideration of long-term aspirin use in CRC prevention. Despite these compelling data, there is a lack of consensus about the balance of risks and benefits associated with long-term aspirin use, particularly in low-risk populations. The optimal dose to use for cancer prevention and the precise mechanism underlying aspirin's anticancer effect require further investigation.

Combination of atorvastatin with sulindac or naproxen profoundly inhibits colonic adenocarcinomas by suppressing the p65/β-catenin/cyclin D1 signaling pathway in rats

Evidence supports the protective role of nonsteroidal anti-inflammatory drugs (NSAID) and statins against colon cancer. Experiments were designed to evaluate the efficacies atorvastatin and NSAIDs administered individually and in combination against colon tumor formation. F344 rats were fed AIN-76A diet, and colon tumors were induced with azoxymethane. One week after the second azoxymethane treatment, groups of rats were fed diets containing atorvastatin (200 ppm), sulindac (100 ppm), naproxen (150 ppm), or their combinations with low-dose atorvastatin (100 ppm) for 45 weeks. Administration of atorvastatin at 200 ppm significantly suppressed both adenocarcinoma incidence (52% reduction, P = 0.005) and multiplicity (58% reduction, P = 0.008). Most importantly, colon tumor multiplicities were profoundly decreased (80%-85% reduction, P < 0.0001) when given low-dose atorvastatin with either sulindac or naproxen. Also, a significant inhibition of colon tumor incidence was observed when given a low-dose atorvastatin with either sulindac (P = 0.001) or naproxen (P = 0.0005). Proliferation markers, proliferating cell nuclear antigen, cyclin D1, and β-catenin in tumors of rats exposed to sulindac, naproxen, atorvastatin, and/or combinations showed a significant suppression. Importantly, colon adenocarcinomas from atorvastatin and NSAIDs fed animals showed reduced key inflammatory markers, inducible nitric oxide synthase and COX-2, phospho-p65, as well as inflammatory cytokines, TNF-α, interleukin (IL)-1β, and IL-4. Overall, this is the first report on the combination treatment using low-dose atorvastatin with either low-dose sulindac or naproxen, which greatly suppress the colon adenocarcinoma incidence and multiplicity. Our results suggest that low-dose atorvastatin with sulindac or naproxen might potentially be useful combinations for colon cancer prevention in humans.

Chemoprevention of colon cancer in a rat carcinogenesis model using a novel nanotechnology-based combined treatment system

Colorectal cancer (CRC) is the third most common cause of cancer death in the United States, accounting for approximately 51,000 deaths each year. We have previously shown in vitro chemopreventive effects of mixtures of aspirin, folic acid, and calcium (AFAC) on colon cancer cell lines. The objective of the present study was to evaluate the in vivo effects of orally administered, colon targeted chemopreventive combination regimens on the inhibition of aberrant crypt foci (ACF) in a rat model of colon carcinogenesis using (i) unmodified (free drug) combinations of AFAC and (ii) nanoparticle-encapsulated combinations of the same agents. A 14-week animal study was conducted in three phases to determine an optimal effective dose from AFAC combinations and evaluate the efficacy of nanotechnology-based chemopreventive regimens administered in combined (mixtures) and individual (single entity) forms. ACF inhibition when compared with azoxymethane-treated rat control group was significant in both the unmodified and the modified nanoparticle-mediated chemopreventive regimens, showing a range of 31% to 38% (P < 0.05) and 50% to 75% (P < 0.001) reduction, respectively, in the number of ACFs. In addition, the nanoparticulate combination regimens of AFAC showed a 2-fold increase in suppression of ACF compared with free drug mixtures. Individual administration of nanoparticle-encapsulated drugs showed no significant effect on the reduction of ACF. Histochemical analysis provided further confirmation of chemopreventive effects, showing a significant reduction in cell nuclear proliferation. Overall, our results provide a strong proof of concept using nanoparticle-mediated combination treatment in the chemoprevention of colon cancer.

Cholesterol and benign prostate disease

The origins of benign prostatic diseases, such as benign prostatic hyperplasia (BPH) and chronic prostatitis/chronic pelvic pain syndrome (CP/CPPS), are poorly understood. Patients suffering from benign prostatic symptoms report a substantially reduced quality of life, and the relationship between benign prostate conditions and prostate cancer is uncertain. Epidemiologic data for BPH and CP/CPPS are limited, however an apparent association between BPH symptoms and cardiovascular disease (CVD) has been consistently reported. The prostate synthesizes and stores large amounts of cholesterol and prostate tissues may be particularly sensitive to perturbations in cholesterol metabolism. Hypercholesterolemia, a major risk factor for CVD, is also a risk factor for BPH. Animal model and clinical trial findings suggest that agents that inhibit cholesterol absorption from the intestine, such as the class of compounds known as polyene macrolides, can reduce prostate gland size and improve lower urinary tract symptoms (LUTS). Observational studies indicate that cholesterol-lowering drugs reduce the risk of aggressive prostate cancer, while prostate cancer cell growth and survival pathways depend in part on cholesterol-sensitive biochemical mechanisms. Here we review the evidence that cholesterol metabolism plays a role in the incidence of benign prostate disease and we highlight possible therapeutic approaches based on this concept.

Chemoprevention for advanced CR neoplasia

Colorectal cancer (CRC) is a major health concern worldwide. In 2011 1,200,000 new cases are predicted and half of them are going to die from the disease. CRC carcinogenesis is a multi-step process that spans over 10-20 years, providing a window of opportunity for effective intervention. CRC can be prevented by life style modification and screening program. However, although these strategies are standard clinical practice, their impact is limited due to low adherence. The number of deaths due to CRC remains alarming high, and makes CRC prevention a paramount. Chemoprevention interferes with the carcinogenesis process by targeting key molecular pathways. It involves the use of a variety of natural or chemical compounds that can delay, prevent or even reverse the adenoma to carcinoma sequence. Numerous chemopreventive agents have been studied but the most efficient are the NSAID group of agents. Much of their efficacy and toxicity has been attributed to their potent inhibition of the cyclooxygenase (COX) enzymes. Chemoprevention has the potential to represent a cost-effective intervention, particularly when targeted at intermediate-risk populations, ages 61-70, following polypectomy. Chemoprevention in this setting is as very important as polyp recurrence in this population can be as high as 50%, even with surveillance colonoscopy every 1-3 years. The most challenging task is to find the proper place for these interventions in the entire effort of general wellbeing. Subjects are likely to be more adherent to prescribed regimens if cancer prevention may be combined with a cardiovascular and Alzheimer prophylaxis. Subjects with a normal colon or non advanced adenomas can be safely monitored with surveillance colonoscopy every 5-10 years. The ideal chemopreventive agent remains to be discovered with great emphasis on the need not to harm. Possibly, combinations of agents will maximize effectiveness while limiting drug toxicity. Finally, personalized approaches would include the ability to predict risk, as well as benefit for a specific individual based on specific SNP's or other genetic profiles.

Coxibs and other nonsteroidal anti-inflammatory drugs in animal models of cancer chemoprevention

Coxibs, including celecoxib, and other nonsteroidal anti-inflammatory drugs (NSAID), including aspirin, are among the most promising cancer chemopreventive agents in development today. This article examines the data on the efficacy of these agents in animal model studies of cancer prevention carried out by the authors. The studies evaluated here are restricted to our rodent models of colon/intestinal, bladder, and nonmelanoma skin cancer, in which celecoxib and other NSAIDs were administered as either cancer preventive or therapeutic agents. These studies may shed light on several questions. Is celecoxib unique compared with other NSAIDs, and if so, what implications would this have for human use? Are standard NSAIDs (which inhibit both COX-1 and COX-2) as effective as celecoxib in animal studies? Is the efficacy of celecoxib in particular or NSAIDs in general due to their off-target effects or to their effects on COX-1 and COX-2? What is the likely efficacy of low-dose aspirin? Some questions raised by human trials and epidemiology are discussed and related to our observations in animal model studies. We also discuss the problem of cardiovascular (CV) events associated with coxibs and certain other NSAIDs and whether results in animal models are predictive of efficacy in humans. On the basis of epidemiologic studies and its CV profile, aspirin seems to be the most promising NSAID for preventing human colorectal, bladder, and skin cancer, although the animal data for aspirin are less clear. A comprehensive understanding of the results of coxibs and other NSAIDs in animal studies may help inform and shape human trials of these commonly employed, relatively inexpensive, and highly effective compounds.

Statin use and colorectal cancer risk according to molecular subtypes in two large prospective cohort studies

Use of statins is hypothesized to reduce colorectal cancer risk but the evidence remains inconsistent. This may be partly explained by differential associations according to tumor location or molecular subtypes of colorectal cancer. We examined the association between statin use and colorectal cancer risk according to tumor location, KRAS mutation status, microsatellite instability (MSI) status, PTGS2 (COX-2) expression, or CpG island methylator phenotype (CIMP) status in two large prospective cohort studies, the Nurses' Health Study and Health Professionals Follow-up Study. We applied Cox regression to a competing risks analysis. We identified 1,818 colorectal cancers during 1990 to 2006. Compared with nonusers, current statin use was not associated with colorectal cancer [relative risk (RR) = 0.99, 95% CI = 0.86-1.14] or colon cancer (RR = 1.10, 95% CI = 0.94-1.29) but was inversely associated with rectal cancer (RR = 0.59, 95% CI = 0.41-0.84, P(heterogeneity) < 0.001). When we examined the association within strata of KRAS mutation status, we found no association with KRAS-mutated cancers (RR = 1.20, 95% CI = 0.87-1.67) but did observe a possible inverse association among KRAS wild-type cancers (RR = 0.80, 95% CI = 0.60-1.06, P(heterogeneity) = 0.06). The association did not substantially differ by PTGS2 expression, MSI status, or CIMP status. Current statin use was not associated with risk of overall colorectal cancer. The possibility that statin use may be associated with lower risk of rectal cancer or KRAS wild-type colorectal cancer requires further confirmation.

Inhibitory effect of dietary atorvastatin and celecoxib together with voluntary running wheel exercise on the progression of androgen-dependent LNCaP prostate tumors to androgen independence

We determined the inhibitory effect of dietary atorvastatin, dietary celecoxib and voluntary running wheel exercise (RW) alone or in combination on the formation and growth of androgen-independent LNCaP tumors in castrated SCID mice. Male SCID mice were injected subcutaneously with androgen-dependent prostate cancer LNCaP cells. When the tumors reached a moderate size, the mice were surgically castrated and treated with atorvastatin (0.02% in the diet), celecoxib (0.05% in the diet) or RW alone or in combination for 42 days. RW or celecoxib alone had a moderate inhibitory effect on the androgen-independent growth of LNCaP tumors, but atorvastatin alone had little or no effect on tumor growth. Combinations of atorvastatin and celecoxib had a stronger inhibitory effect on the formation and growth of androgen-independent LNCaP tumors than either drug alone. A combination of RW together with atorvastatin and celecoxib had the most potent inhibitory effect on the progression of LNCaP tumors to androgen independent growth. The serum concentration of atorvastatin after two weeks of oral administration of atorvastatin was 6.1 ng/ml. The serum concentration of celecoxib after treatment with dietary celecoxib for two weeks was 1090 ng/ml. The serum concentration of atorvastatin but not that of celecoxib was substantially reduced when the two drugs were given in combination. The drug concentrations observed in our animal studies are comparable or less than those commonly found in humans treated with atorvastatin or celecoxib. Our results indicate that administration of atorvastatin and celecoxib together with voluntary exercise may be an effective strategy for the prevention of prostate cancer progression from androgen dependence to androgen independence.

Colorectal cancer risk in relation to antidepressant medication use

Laboratory studies suggest that antidepressants affect the risk of some cancers, including colorectal cancer. To investigate whether selective serotonin reuptake inhibitors (SSRIs) and tricyclic antidepressants (TCAs) are associated with colorectal cancer risk, we conducted a case-control study among enrollees of an integrated healthcare delivery system in Washington State. Cases were first diagnosed with invasive colorectal cancer between 2000 and 2003; controls were randomly selected from Group Health enrollees and matched to cases on age, sex and length of enrollment before diagnosis/reference date. We used logistic regression to estimate odds ratios (OR) and 95% confidence intervals (CI) for colorectal cancer in relation to use of any antidepressant, SSRIs only or TCAs only, among 649 cases and 656 controls. Use of any antidepressant was associated with a reduced risk of colorectal cancer (OR = 0.7, 95% CI = 0.5-0.9). Associations were similar for persons who used SSRIs exclusively (OR = 0.7, 95% CI = 0.4-1.1) and TCAs exclusively (OR = 0.7, 95% CI = 0.5-1.2); however, this reduction in risk appeared limited to persons without a prior cancer at another site. Our data support findings from previous epidemiologic and animal studies that suggest antidepressants may reduce the risk of colorectal cancer. Future studies with larger sample sizes should further examine individual drugs as well as dose, duration and recency of use.

Atorvastatin induces apoptosis in vitro and slows growth of tumor xenografts but not polyp formation in MIN mice

BACKGROUND

Despite the availability of effective surveillance for colorectal cancer with colonoscopy, relatively few at-risk individuals utilize this option. Colon cancer chemoprevention might be a more acceptable alternative. Some epidemiologic studies have suggested that statins may have chemopreventive effects without the risks of nonsteroidal anti-inflammatory drugs, but other epidemiologic studies have found no effect of statins.

METHODS

We aimed to evaluate the efficacy of atorvastatin in inducing apoptosis in vitro, in preventing polyp formation in the min mouse, and in preventing tumor growth in nude mice.

RESULTS

Atorvastatin rapidly induces apoptosis in the HCT116 colon cancer cell line in vitro, and this effect is reversible with mevalonate and geranylgeranyl pyrophosphate, but less so by farnesyl pyrophosphate. Atorvastatin chow was ineffective in reducing polyp formation in the min mouse model, with no significant effect on polyp number. Atorvastatin was effective in significantly slowing the growth of HCT116 colon cancer cell xenografts in nude mice (p = 0.008). Further, this reduction is due to increased levels of apoptosis.

CONCLUSIONS

Atorvastatin can induce apoptosis in vitro, through mevalonate and prenylation pathways. Atorvastatin, while not effective in preventing polyp formation in the min mouse model, was very effective in slowing tumor growth in a nude mouse model. Consistent with in vitro findings, increased apoptosis accounted for decreased tumor growth. Statins may have benefit in cancer by slowing tumor growth, rather than preventing tumor initiation.

The use of animal models for cancer chemoprevention drug development

Animal models currently are used to assess the efficacy of potential chemopreventive agents, including synthetic chemicals, chemical agents obtained from natural products, and natural product mixtures. The observations made in these models as well as other data are then used to prioritize agents to determine which are qualified to progress to clinical chemoprevention trials. Organ-specific animal models are employed to determine which agents or classes of agents are likely to be the most effective at nontoxic doses to prevent organ-specific forms of cancer. These results are then used to target specific organs in high-risk populations in clinical trials. The animal models used are either carcinogen-induced with carcinogens specific for particular organ sites or they are transgenic/mutant animals with insertions, deletions, or mutations at targeted gene sites known to enhance cancers in a specific organ. Animal tumor models with characteristics favorable to chemoprevention studies are available for cancers of the lung, colon, skin, bladder, mammary, prostate, head and neck, esophagus, ovary, and pancreas. In addition to single-agent dose-response testing, such models are frequently used for testing combinations of agents, testing different routes of administration, evaluating surrogate endpoint biomarkers, and generating initial pharmacokinetics and toxicology data. For some of the more standard animal models there is significant correlation with human chemopreventive trial results. There are a growing number of positive human chemoprevention trials that have used agents or combinations that were positive in animal testing. There have been fewer negative human clinical trials, but their results again correlate with negative animal results. Clearly the validation of animal models to predict the efficacy of agents in human clinical trials will await further human data on positive and negative outcomes with chemopreventive agents. Whether validated or not, animal efficacy data remain central to the clinical trial decision-making process.

Statin use and colorectal adenoma risk: results from the adenoma prevention with celecoxib trial

Statins are widely prescribed for cardiovascular disease prevention and also commonly used in patients at high risk for colorectal cancer. We report the results of a planned secondary analysis of the relationship between statin use and colorectal adenoma risk in a large chemoprevention trial. The Adenoma Prevention with Celecoxib (APC) trial randomized 2,035 adenoma patients to receive placebo (679 patients), 200 mg celecoxib twice daily (bid; 685 patients), or 400 mg celecoxib bid (671 patients). The study collected complete medical history and medication use data and performed colonoscopic surveillance to 5 years after study enrollment. The effects of statin use on newly detected adenomas and cardiovascular adverse events were analyzed as time-dependent variables by multivariable Cox regression. Statins were used by 36% (n = 730) of APC trial participants. When adjusted for covariates including cardioprotective aspirin use, age, and sex, participants on the placebo arm who used statins at any time had no benefit over 5 years compared with never users (risk ratio, 1.24; 95% confidence interval, 0.99-1.56; P = 0.065). Statin use for >3 years increased adenoma risk over 5 years (risk ratio, 1.39; 95% confidence interval, 1.04-1.86; P = 0.024). For all comparisons of patients treated with celecoxib, adenoma detection rates for statin users and nonusers were equivalent. Consistent with their use in patients at high risk, cardiovascular serious adverse events were more common among statin users. For patients at high risk of colorectal cancer, statins do not protect against colorectal neoplasms and may even increase the risk of developing colorectal adenomas.

Statins can modulate effectiveness of antitumor therapeutic modalities

Despite significant, frequently very strong, antiproliferative and tumoricidal effects of statins demonstrated in vitro, their antitumor effects in animal models are modest, and their efficacy in clinical trials has not been proven. As such, statins seem unlikely to be ever regarded as antitumor agents. However, statins are regularly taken by many elderly cancer patients for the prevention of cardiovascular events. Owing to their pleiotropic effects in normal and tumor cells, statins interact in various ways with many antitumor treatment modalities, either potentiating or diminishing their effectiveness. Elucidation of these interactions might affect the choice of treatment to be planned in cancer patients as some combinations might be contraindicated, whereas others might elicit potentiated antitumor effects but at a cost of increased general toxicity. Some other combinations might induce either comparable or even stronger antitumor effects, but with a beneficial concomitant reduction of specific side effects. Most of the studies reviewed in this article have been carried in vitro or in experimental tumor models, but clinical relevance of the findings is also discussed.

Atorvastatin and celecoxib in combination inhibits the progression of androgen-dependent LNCaP xenograft prostate tumors to androgen independence

Epidemiology studies suggest that statins and nonsteroidal anti-inflammatory drugs reduce the risk of prostate cancer. In the present study, LNCaP cells were cultured in regular medium containing fetal bovine serum or in medium supplemented with charcoal-stripped fetal bovine serum to mimic androgen deprivation treatment. We found that atorvastatin (Lipitor) or celecoxib (Celebrex) treatment of LNCaP cells cultured in regular or androgen-depleted medium inhibited growth and stimulated apoptosis. A combination of atorvastatin and celecoxib was more effective than either agent alone. In animal studies, severe combined immunodeficient mice were injected s.c. with LNCaP cells in Matrigel. After 4 to 6 weeks, mice with LNCaP tumors (about 0.6 cm wide and 0.6 cm long) were surgically castrated and received daily i.p. injections of vehicle, atorvastatin (10 microg/g body weight/d), celecoxib (10 microg/g/d), or a combination of atorvastatin (5 microg/g/d) and celecoxib (5 microg/g/d) for 42 days. In all groups, the androgen-dependent LNCaP tumors regressed initially in response to castration, but the tumors eventually progressed to androgen independence and started to grow. Treatment of the mice with atorvastatin or celecoxib alone suppressed the regrowth of LNCaP tumors after castration. A combination of low doses of atorvastatin and celecoxib had a more potent effect in inhibiting the growth and progression of LNCaP tumors to androgen independence than a higher dose of either agent alone. Our results indicate that administration of a combination of atorvastatin and celecoxib may be an effective strategy for the prevention of prostate cancer progression from androgen dependence to androgen independence.

Reduction in low-density lipoprotein cholesterol levels during statin therapy is associated with a reduced incidence of advanced colon polyps

BACKGROUND

Elevated serum cholesterol levels may stimulate proliferation in adenomatous polyps (AP). Our aim was to determine how a reduction of low-density lipoprotein (LDL) cholesterol levels in patients taking statins influences the incidence of APs.

METHODS

We performed a retrospective study of patients taking statins who were found to have > or =1 APs on an index colonoscopy, and who also had a follow-up colonoscopy within 3 to 5 years. Patients were divided into 2 groups: (1) those with > or =30% reduction in LDL levels and (2) those with < 30% reduction in LDL levels during the interval between colonoscopies. Univariate and multivariate analysis were evaluated for their association with advanced APs.

RESULTS

We identified 231 patients. Univariate analysis showed that patients with > or =30% LDL reduction had fewer mean total numbers of APs (2.6 versus 3.3, P = 0.02), fewer advanced APs (14% versus 26%, P = 0.04), and smaller APs (5 mm versus 6.1 mm, P = 0.01) than those with <30% reduction in LDL. Multiple logistic regression analysis confirmed that > or =30% LDL reduction was associated with smaller APs (P < 0.01). Subjects with > or =30% LDL reduction also had a 53% reduced incidence of advanced APs (OR, 0.47; CI, 0.22-0.96; P < 0.05). These findings remained significant even when adjusted for nonsteroidal antiinflammatory drug use, age, family history of APs, and body mass index.

CONCLUSIONS

A reduction in LDL levels of > or=30% during a 3- to 5-year period of statin therapy was associated with a 53% reduction in the incidence of advanced APs, even after adjustment for other known polyp risk factors.