Sulindac for polyposis of the colon

Microbiota-associated mechanisms in colorectal cancer

Colorectal cancer (CRC) is one of the most common cancers worldwide, ranking third in terms of incidence and second as a cause of cancer-related death. There is growing scientific evidence that the gut microbiota plays a key role in the initiation and development of CRC. Specific bacterial species and complex microbial communities contribute directly to CRC pathogenesis by promoting the neoplastic transformation of intestinal epithelial cells or indirectly through their interaction with the host immune system. As a result, a protumoural and immunosuppressive environment is created conducive to CRC development. On the other hand, certain bacteria in the gut microbiota contribute to protection against CRC. In this chapter, we analysed the relationship of the gut microbiota to CRC and the associations identified with specific bacteria. Microbiota plays a key role in CRC through various mechanisms, such as increased intestinal permeability, inflammation and immune system dysregulation, biofilm formation, genotoxin production, virulence factors and oxidative stress. Exploring the interaction between gut microbiota and tumourigenesis is essential for developing innovative therapeutic approaches in the fight against CRC.

The Past and Future of Inflammation as a Target to Cancer Prevention

Inflammation is an essential defense mechanism in which innate immune cells are coordinately activated on encounter of harmful stimuli, including pathogens, tissue injury, and toxic compounds and metabolites to neutralize and eliminate the instigator and initiate healing and regeneration. Properly terminated inflammation is vital to health, but uncontrolled runaway inflammation that becomes chronic begets a variety of inflammatory and metabolic diseases and increases cancer risk. Making damaged tissues behave as "wounds that do not heal" and sustaining the production of growth factors whose physiologic function is tissue healing, chronic inflammation accelerates cancer emergence from premalignant lesions. In 1863, Rudolf Virchow, a leading German pathologist, suggested a possible association between inflammation and tumor formation, but it took another 140 years to fully elucidate and appreciate the tumorigenic role of inflammation. Key findings outlined molecular events in the inflammatory cascade that promote cancer onset and progression and enabled a better appreciation of when and where inflammation should be inhibited. These efforts triggered ongoing research work to discover and develop inflammation-reducing chemopreventive strategies for decreasing cancer risk and incidence.

Berries vs. Disease: Revenge of the Phytochemicals

Secondary metabolites and phytochemicals in plant-based diets are known to possess properties that inhibit the development of several diseases including a variety of cancers of the aerodigestive tract. Berries are currently of high interest to researchers due to their high dietary source of phytochemicals. Black raspberries (BRB), Rubus occidentalis, are of special interest due to their rich and diverse composition of phytochemicals. In this review, we present the most up-to-date preclinical and clinical data involving berries and their phytochemicals in the chemoprevention of a variety of cancers and diseases. BRBs possess a variety of health benefits including anti-proliferative properties, anti-inflammatory activity, activation of pro-cell-death pathways, modulation of the immune response, microbiome modulation, reduction in oxidative stress, and many more. However, little has been done in both preclinical and clinical settings on the effects of BRB administration in combination with other cancer therapies currently available for patients. With the high potential for BRBs as chemopreventive agents, there is a need to investigate their potential in combination with other treatments to improve therapeutic efficacy.

Chemoprevention in hereditary digestive neoplasia: A comprehensive review

Hereditary syndromes, such as familial adenomatous polyposis (FAP), MUTYH polyposis or Lynch syndrome, are particularly predisposing to the development of colorectal cancer. These situations have necessitated the development of adapted prevention strategies based largely on reinforced endoscopic surveillance and the search for complementary prevention strategies. This is the case for chemoprevention, which is the long-term administration of chemical agents limiting carcinogenesis, used as primary or secondary prophylaxis. The aim of this review is to present the available literature and the latest advances in chemoprevention in patients with FAP or MUTYH and other polyposis as well as in patients with Lynch syndrome. The main conclusions of the few available guidelines in these situations are also discussed.

Endoscopic and chemopreventive management of familial adenomatous polyposis syndrome

Familial adenomatous polyposis (FAP) is an autosomal dominant syndrome predisposing affected individuals to gastrointestinal (GI) cancers through a high burden of polyposis. Colorectal cancer rates reach 100% by the age of 45, making early colectomy a mainstay of treatment. While most patients undergo colectomy at an early age, ongoing screening and surveillance of the upper gastrointestinal tract and rectal pouch must continue throughout adulthood. Endoscopic therapy of gastric, duodenal, ampullary and rectal pouch polyps is critical to reduce morbidity and cancer related mortality. Management of these lesions is not uniform, and is dependent on their location, size, histology, and risk of malignant potential. Medical therapies targeting pathways that reduce the malignant progression of pre-cancerous lesions have been studied for many years. While studies on the use of aspirin and non-steroidal anti-inflammatories (NSAIDs) in chemoprevention have shown encouraging results in Lynch syndrome and primary colorectal cancer, the potential benefits of these medications have not been duplicated in FAP cohorts. While data remains limited on chemoprevention in FAP, a number of randomized trials are currently underway examining targeted therapies with the potential to slow the progression of the disease. This review aims to provide an in-depth review of the literature on current endoscopic options and chemopreventive therapies targeting FAP. While the endoscopic management has robust data for its use, chemoprevention in FAP is still in its infancy. The complementary use of chemopreventive agents and endoscopic therapy for FAP patients is quickly becoming a growing and exciting area of research.

The effect of sulindac on redox homeostasis and apoptosis-related proteins in melanotic and amelanotic cells

BACKGROUND

Non-steroidal anti-inflammatory drugs have been shown to inhibit the development of induced neoplasms. Our previous research demonstrated that the cytotoxicity of sulindac against melanoma cells is comparable to dacarbazine, the drug used in chemotherapy. The aim of this study was to investigate the mechanism of sulindac cytotoxicity on COLO 829 and C32 cell lines.

METHODS

The influence of sundilac on the activity of selected enzymes of the antioxidant system (superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GPx)) and the content of hydrogen peroxide as well as the level of proteins initiating (p53, Bax) and inhibiting (Bcl-2) apoptosis were measured in melanoma cells.

RESULTS

In melanotic melanoma cells, sulindac increased the activity of SOD and the content of H2O2 but decreased the activity of CAT and GPx. The level of p53 and Bax proteins rose but the content of Bcl-2 protein was lowered. Similar results were observed for dacarbazine. In amelanotic melanoma cells, sulindac did not cause an increase in the activity of measured enzymes or any significant changes in the level of apoptotic proteins.

CONCLUSION

The cytotoxic effect of sulindac in the COLO 829 cell line is connected to disturbed redox homeostasis by changing the activity of SOD, CAT, GPx, and level of H2O2. Sulindac also induces apoptosis by changing the ratio of the pro-apoptotic/anti-apoptotic protein. The presented studies indicate the possibility of developing target therapy against melanotic melanoma using sulindac.

The Effect of Acetylsalicylic Acid, as a Representative Non-Steroidal Anti-Inflammatory Drug, on the Activity of Myeloperoxidase

BACKGROUND

Acetylsalicylic acid (ASA or aspirin) is one of the world's most widely used non-steroidal anti-inflammatory drug (NSAID). Numerous studies have shown that the long-term use of aspirin may contribute to longer survival among patients with various types of cancer, including ovarian cancer.

AIM

The aim of this study was to investigate the effect of ASA on myeloperoxidase (MPO), which is found at an elevated level in women with ovarian cancer, among others.

METHODS

The influence of different concentrations of ASA on the chlorinating and peroxidase activity of MPO was analysed. The relationship between the concentration of ASA and the degree of inhibition of MPO activity was determined based on the results.

CONCLUSIONS

Aspirin has a significant effect on MPO activity. The use of 50 mM ASA resulted in the enzyme activity being inhibited by more than 90%.

Corosolic Acid Inhibits Secretory Phospholipase A2IIa as an Anti-Inflammatory Function and Exhibits Anti-Tumor Activity in Ehrlich Ascites Carcinoma Bearing Mice

Background

Inflammation is generally connected to tumour progression and development. The secretory phospholipase A2IIa (sPLA2IIa) is an important inflammatory enzyme that catalyse the hydrolysis of membrane phospholipids into arachidonic and lysophosphatidic acid, which are the precursors for production of a lot of pro-inflammatory mediators like prostaglandins, prostacyclins, thromboxanes, leukotrienes and platelet activating factors, which involved in the proliferation, migration, invasion, and metastasis. Therefore, investigating safe and effective sPLA2IIa inhibitors as a therapeutic agent to treat cancer is indeed in need.

Methods

Anti-inflammatory function of corosolic acid was evaluated by docking it with sPLA2IIa enzyme, sPLA2IIa inhibition, calcium and substrate concentration-dependent assays; intrinsic fluorescence and UV-CD analysis; neutralisation of sPLA2IIa induced indirect hemolytic and edema. Evaluated the anticancer activity of corosolic acid by MTT assays and caspase-3 expression; the anti-tumour activity by EAC-induced cell line and interleukin 6 expression.

Results

The corosolic acid inhibits sPLA2IIa activity to 82.21±2.82%. The inhibition was evaluated by increasing calcium from 2.5 to 15 µM and substrate from 20 to 120 nM, it did not affect the level of inhibition. Corosolic acid altered the intrinsic fluorescence and UV-CD spectra of sPLA2IIa enzyme, indicating the direct interaction. It neutralised sPLA2IIa induced hemolytic activity from 97±1.23% to 15.75±1.44% and edema from 171.51±2.39% to 119.3±2.6%. Further, as antiproliferative activity, corosolic acid reduced the PC3 cell viability from 99.66±0.57% to 23±2.64% and suppressed LPS-induced IL-6 level from 94.35±2.2% to 34.36±2.4%. It increased mean survivability time from 30 to 38 days and displayed the drug-like qualities.

Conclusion

All the experimental results have proven the corosolic acid as an anti-inflammatory and anticancer molecule that may further be used to develop it as a drug.

Lone J, Giresha AS, Krishna Ram H, Manjunatha JG, El-Serehy HA, Narayanappa M, Shankar J, Bhardwaj R, Ahmad Guru S, Dharmappa KK. Quercitrin neutralizes sPLA2IIa activity, reduces the inflammatory IL-6 level in PC3 cell lines, and exhibits anti-tumor activity in the EAC-bearing mice model

Human phospholipase A2 group IIa (sPLA2IIa) is an inflammatory enzyme that plays a significant role in tumorigenesis. Inhibiting the sPLA2IIa enzyme with an effective molecule can reduce the inflammatory response and halt cancer progression. The present study evaluates quercitrin, a biflavonoid, for sPLA2IIa inhibition and anticancer activity. Quercitrin inhibited sPLA2IIa activity to a greater extent-at 86.24% ± 1.41 with an IC50 value of 8.77 μM ± 0.9. The nature of sPLA2IIa inhibition was evaluated by increasing calcium concentration from 2.5 to 15 µM and substrate from 20 to 120 nM, which did not alter the level of inhibition. Intrinsic fluorescence and far UV-CD studies confirmed the direct interaction of quercitrin with the sPLA2IIa enzyme. This significantly reduced the sPLA2IIa-induced hemolytic activity and mouse paw edema from 97.32% ± 1.23-16.91% ± 2.03 and 172.87% ± 1.9-118.41% ± 2.53, respectively. As an anticancer activity, quercitrin reduced PC-3 cell viability from 98.66% ± 2.51-18.3% ± 1.52 and significantly decreased the IL-6 level in a dose-dependent manner from 98.35% ± 2.2-37.12% ± 2.4. It increased the mean survival time (MST) of EAC-bearing Swiss albino mice from 30 to 35 days. It obeyed Lipinski's rule of five, suggesting a druggable property. Thus, all the above experimental results were promising and encouraged further investigation into developing quercitrin as a therapeutic drug for both inflammatory diseases and cancers.

Colorectal Carcinoma, Cyclooxygenases, and COX Inhibitors

Colorectal carcinoma (CRC) is the most common of gastrointestinal cancers, the majority presenting with sporadic occurrence compared to the less frequently inherited syndromes. The increasing incidence, decreasing gender and age disparities, and the prevalent risk factors are concerning. The malignancy arising from benign precursor polyps transforms slowly over time. The adenoma variant polyps reported a marked upregulation of cyclooxygenases (COX), significantly COX-2 isoform, influenced by various determinants such as genetics, pathology, histology, and site of the carcinoma. These COX enzymes are responsible for prostaglandin synthesis and the consequent cascade of cell inflammation and proliferation. Therefore, COX inhibition by non-steroidal anti-inflammatory drugs (NSAIDs) targeted against both the isoforms COX-1 and COX-2 have been studied for decades in anticipation of preventing the occurrence of colorectal carcinoma in high-risk populations. This article has collated and highlighted the overexpression of COX enzymes by the adenomatous polyps and provides corroborating evidence from multiple studies in favor of COX inhibition by NSAIDs. Aspirin and Sulindac were two drugs to be initially proven to halt the progression and cause regression of the polyps. Celecoxib, a selective COX-2 inhibitor besides NSAIDs, was also used in experimental studies.

New Organoselenium (NSAIDs-Selenourea and Isoselenocyanate) Derivatives as Potential Antiproliferative Agents: Synthesis, Biological Evaluation and in Silico Calculations

In this study, we report on the synthesis of new organoselenium derivatives, including nonsteroidal anti-inflammatory drugs (NSAIDs) scaffolds and Se functionalities (isoselenocyanate and selenourea), which were evaluated against four types of cancer cell line: SW480 (human colon adenocarcinoma cells), HeLa (human cervical cancer cells), A549 (human lung carcinoma cells), MCF-7 (human breast adenocarcinoma cells). Among these compounds, most of the investigated compounds reduced the viability of different cancer cell lines. The most promising compound 6b showed IC₅₀ values under 10 μM against the four cancer cell lines, particularly to HeLa and MCF-7, with IC₅₀ values of 2.3 and 2.5 μM, respectively. Furthermore, two compounds, 6b and 6f, were selected to investigate their ability to induce apoptosis in MCF-7 cells via modulation of the expression of anti-apoptotic Bcl-2 protein, pro-inflammatory cytokines (IL-2) and proapoptotic caspase-3 protein. The redox properties of the NSAIDs-Se derivatives were conducted by 2, 2-didiphenyl-1-picrylhydrazyl (DPPH), bleomycin-dependent DNA damage and glutathione peroxidase (GPx)-like assays. Finally, a molecular docking study revealed that an interaction with the active site of thioredoxin reductase 1 (TrxR1) predicted the antiproliferative activity of the synthesized candidates. Overall, these results could serve as a promising launch point for further designs of NSAIDs-Se derivatives as potential antiproliferative agents.

The efficacy and safety of sulindac for colorectal polyps: A protocol for systematic review and meta-analysis

BACKGROUND

Sulindac has been used for treating colorectal polyps widely. However, the efficacy and safety of sulindac for colorectal polyps are unclear. This study aims to evaluate the efficacy and safety of sulindac for colorectal polyps.

METHODS

Randomized controlled trials of sulindac in the treatment of colorectal polyps will be searched in PubMed, EMbase, Cochrane Library, Web of Science, China National Knowledge Infrastructure (CNKI), WanFang, the Chongqing VIP Chinese Science, and Technology Periodical Database, and China biomedical literature database (CBM) from inception to August, 2020. And Baidu Scholar, Google Scholar, International Clinical Trials Registry Platform, and Chinese Clinical Trials Registry will be searched to obtain more relevant studies comprehensively. Two researchers will perform data extraction and risk of bias assessment independently. Statistical analysis will be conducted in RevMan 5.3.

RESULTS

This study will summarize the present evidence by exploring the efficacy and safety of sulindac in the treatment of colorectal polyps.

CONCLUSION

The findings of the study will provide helpful evidence for the efficacy and safety of sulindac in the treatment of colorectal polyps, facilitating clinical practice and further scientific studies.

ETHICS AND DISSEMINATION

The private information from individuals will not publish. This systematic review also will not involve endangering participant rights. Ethical approval is not required. The results may be published in a peer-reviewed journal or disseminated in relevant conferences.

OSF REGISTRATION NUMBER

DOI 10.17605/OSF.IO/N5GDH.

Anti-Inflammatory Drugs as Anticancer Agents

Inflammation is strictly associated with cancer and plays a key role in tumor development and progression. Several epidemiological studies have demonstrated that inflammation can predispose to tumors, therefore targeting inflammation and the molecules involved in the inflammatory process could represent a good strategy for cancer prevention and therapy. In the past, several clinical studies have demonstrated that many anti-inflammatory agents, including non-steroidal anti-inflammatory drugs (NSAIDs), are able to interfere with the tumor microenvironment by reducing cell migration and increasing apoptosis and chemo-sensitivity. This review focuses on the link between inflammation and cancer by describing the anti-inflammatory agents used in cancer therapy, and their mechanisms of action, emphasizing the use of novel anti-inflammatory agents with significant anticancer activity.

Arylpropionic acid-derived NSAIDs: New insights on derivatization, anticancer activity and potential mechanism of action

NSAIDs displayed chemopreventive and anticancer effects against several types of cancers. Moreover, combination of NSAIDs with anticancer agents resulted in enhanced anticancer activity. These findings have attracted much attention of researchers working in this field. The 2-arylpropionic acid-derived NSAIDs represent one of the most widely used anti-inflammatory agents. Additionally, they displayed antiproliferative activities against different types of cancer cells. Large volume of research was performed to identify molecular targets responsible for this activity. However, the exact mechanism underlying the anticancer activity of profens is still unclear. In this review article, the anticancer potential, structure activity relationship and synthesis of selected profen derivatives were summarized. This review is focused also on non-COX targets which can mediate the anticancer activity of this derivatives. The data in this review highlighted profens as promising lead compounds in future research to develop potent and safe anticancer agents.

Targeting lipid mediators in cancer biology

Bioactive lipids are essential components of human cells and tissues. As discussed in this review, the cancer lipidome is diverse and malleable, with the ability to promote or inhibit cancer pathogenesis. Targeting lipids within the tumor and surrounding microenvironment may be a novel therapeutic approach for treating cancer patients. Additionally, the emergence of a novel super-family of lipid mediators termed specialized pro-resolving mediators (SPMs) has revealed a new role for bioactive lipid mediators in the resolution of inflammation in cancer biology. The role of SPMs in cancer holds great promise in our understanding of cancer pathogenesis and can ultimately be used in future cancer diagnostics and therapy.

Progress in preventive therapy for cancer: a reminiscence and personal viewpoint

Prophylactic drug treatment with aspirin, statins and anti-hypertensive agents has had a major impact on the incidence of cardiovascular disease and is now well established. Progress in therapeutic cancer prevention has been much slower; only recently have effective agents been clearly established. Breast cancer has led the way and endocrine agents used to treat it-notably tamoxifen and the aromatase inhibitors-have now been shown to have a substantial preventive effect as well. However, these agents carry some toxicity and thus identifying high-risk women who are likely to benefit most is a key priority. In contrast, the ability of low-dose aspirin to prevent about one-third of colorectal, gastric, and oesophageal cancers, combined with its much lower toxicity profile, make it attractive for a much larger proportion of the general population. Vaccination against the human papilloma virus is also a preventive intervention with large benefits for the whole population. Here I recall my involvement in these initiatives and offer a personal viewpoint on what has been achieved and what remains to be done.

Cancer-preventive Properties of an Anthocyanin-enriched Sweet Potato in the APCMIN Mouse Model

Background

Anthocyanin-rich foods and preparations have been reported to reduce the risk of life-style related diseases, including cancer. The SL222 sweet potato, a purple-fleshed cultivar developed in New Zealand, accumulates high levels of anthocyanins in its storage root.

Methods

We examined the chemopreventative properties of the SL222 sweet potato in the C57BL/6J-APC^MIN/+ (APC^MIN) mouse, a genetic model of colorectal cancer. APC^MIN and C57BL/6J wild-type mice (n=160) were divided into four feeding groups consuming diets containing 10% SL222 sweet potato flesh, 10% SL222 sweet potato skin, or 0.12% ARE (Anthocyanin rich-extract prepared from SL222 sweet potato at a concentration equivalent to the flesh-supplemented diet) or a control diet (AIN-76A) for 18 weeks. At 120 days of age, the mice were anaesthetised, and blood samples were collected before the mice were sacrificed. The intestines were used for adenoma enumeration.

Results

The SL222 sweet potato-supplemented diets reduced the adenoma number in the APC^MIN mice.

Conclusions

These data have significant implications for the use of this sweet potato variant in protection against colorectal cancer.

Chemoprevention of familial adenomatous polyposis

Familial adenomatous polyposis (FAP) has always been first and foremost a surgical disease, whose treatment with colectomy has long been known to reduce risk of premature cancer death. The notion of reducing polyp burden and potentially delaying surgical intervention has spawned a host of "chemoprevention" trials. In this paper I selectively review the findings from these studies, highlighting trial design issues and in particular some of the limitations of historical and existing trial endpoint measures. Nonsteroidal anti-inflammatory agents have been the most commonly employed chemopreventive agents. Sulindac, largely by historical accident, has been the most extensively studied, and is widely considered the standard of care when a clinical decision to intervene medically is made. Newer trials are evaluating combinations of agents in order to take advantage of differing mechanisms of action, in the hope of achieving synergy, as no single agent predictably or completely suppresses adenoma growth. Some of these studies and other single-agent interventions are discussed, though an exploration of the various mechanisms of action is beyond the scope of this paper. It is essential that future trials focus on the issue of "clinical benefit", not simply because the US Food and Drug Administration has insisted on it, but because only real evidence-based advances can improve the standard of medical care for FAP patients. Hence my focus on issues of trial design and clinically relevant endpoints.

Potentiating the effects of radiotherapy in rectal cancer: the role of aspirin, statins and metformin as adjuncts to therapy

BACKGROUND

Complete tumour response (pCR) to neo-adjuvant chemo-radiotherapy for rectal cancer is associated with a reduction in local recurrence and improved disease-free and overall survival, but is achieved in only 20-30% of patients. Drug repurposing for anti-cancer treatments is gaining momentum, but the potential of such drugs as adjuncts, to increase tumour response to chemo-radiotherapy in rectal cancer, is only just beginning to be recognised.

METHODS

A systematic literature search was conducted and all studies investigating the use of drugs to enhance response to neo-adjuvant radiation in rectal cancer were included. 2137 studies were identified and following review 12 studies were extracted for full text review, 9 studies were included in the final analysis.

RESULTS

The use of statins or aspirin during neo-adjuvant therapy was associated with a significantly higher rate of tumour downstaging. Statins were identified as a significant predictor of pCR and aspirin users had a greater 5-year progression-free survival and overall survival. Metformin use was associated with a significantly higher overall and disease-free survival, in a subset of diabetic patients.

CONCLUSIONS

Aspirin, metformin and statins are associated with increased downstaging of rectal tumours and thus may have a role as adjuncts to neoadjuvant treatment, highlighting a clear need for prospective randomised controlled trials to determine their true impact on tumour response and overall survival.

R-Flurbiprofen Traps Prostaglandins within Cells by Inhibition of Multidrug Resistance-Associated Protein-4

R-flurbiprofen is the non-COX-inhibiting enantiomer of flurbiprofen and is not converted to S-flurbiprofen in human cells. Nevertheless, it reduces extracellular prostaglandin E₂ (PGE₂) in cancer or immune cell cultures and human extracellular fluid. Here, we show that R-flurbiprofen acts through a dual mechanism: (i) it inhibits the translocation of cPLA_2α to the plasma membrane and thereby curtails the availability of arachidonic acid and (ii) R-flurbiprofen traps PGE₂ inside of the cells by inhibiting multidrug resistance–associated protein 4 (MRP4, ABCC4), which acts as an outward transporter for prostaglandins. Consequently, the effects of R-flurbiprofen were mimicked by RNAi-mediated knockdown of MRP4. Our data show a novel mechanism by which R-flurbiprofen reduces extracellular PGs at physiological concentrations, particularly in cancers with high levels of MRP4, but the mechanism may also contribute to its anti-inflammatory and immune-modulating properties and suggests that it reduces PGs in a site- and context-dependent manner.

Synthesis and Biological Evaluation of Novel Indomethacin Derivatives as Potential Anti-Colon Cancer Agents

The molecular structure of indomethacin was used as a starting scaffold for the synthesis of 20 novel analogs and to study their effects on the proliferation of three human colon cancer cell lines, HCT-116, HT-29, and Caco-2, by MTT assay. The synthesized indomethacin analogs were characterized on the basis of IR, ¹ H NMR, ¹³ C NMR, mass spectral data, and elemental analysis results. Cytotoxicity assay results showed that the indomethacin amide analog 2 was the most potent anticancer agent (IC₅₀  = 0.78, 0.09, and 0.0127 μg/mL) against the three colon cancer cell lines, respectively, being more potent than the standard 5-fluorouracil (IC₅₀  = 1.8, 0.75, and 5.45 μg/mL). Interestingly, the indomethacin oxazin analog 3 and the indomethacin amide analog 8 displayed very potent anticancer activity against the HCT-116 cell line with IC₅₀  = 0.421 and 0.27 μg/mL, respectively, much better than the reference (IC₅₀  = 1.8 μg/mL). Additionally, analogs 3, 4b, 11, 12c, and 13a exhibited excellent antitumor activity against Caco-2 cells, with IC₅₀ ranging from 1.5 to 4.5 μg/mL. Furthermore, analogs 2 and 8 were additionally examined for their effect on the cell cycle of HCT-116 and HT-29 cells, respectively, using flow cytometric analysis. Analog 2 arrested the cell cycle of HT-29 cells at the S phase, while 8 was found to arrest the cell cycle of HCT-116 cells at the G0/G1 phase.

Familial adenomatous polyposis in China

Familial adenomatous polyposis (FAP) is an autosomal dominant disease with a poor prognosis, and has been studied by clinicians and geneticists in China for the past three decades. It is estimated that FAP has an incidence of between 1 in 8,000 and 1 in 10,000 individuals, and accounts for 0.94% of colorectal cancer cases in China. Recent advances in the understanding of FAP suggest that the genotype of the patient may allow for early diagnosis and surveillance, and guide surgical and chemopreventive management. However, the genetic mechanisms of FAP vary between different countries. FAP in China has its own characteristics, and this may be due to ethnic and geographical genetic variation. In the present review the clinical manifestations and genetics of FAP in China are discussed, as well as the surgical strategies, chemotherapeutics and traditional Chinese medicines used in its treatment. Increased insight into the genetic and clinical features of FAP in the Chinese population may aid in the prevention and management of the disorder.

Use of NSAIDs for the Chemoprevention of Colorectal Cancer

OBJECTIVE:

To discuss the role of nonsteroidal antiinflammatory drugs (NSAIDs) in the chemoprevention of colorectal cancer.

DATA SOURCES:

A MEDLINE search (1966–May 2003) was performed to identify key literature. Search items included, but were not limited to, NSAIDs, colorectal cancer, chemoprevention, cyclooxygenase-2 (COX-2)–specific inhibitors, and familial adenomatous polyposis (FAP).

STUDY SELECTION AND DATA EXTRACTION:

The search included experimental (in vitro and animal models) and clinical studies evaluating the use of NSAIDs for the chemoprevention of colorectal cancer. The MEDLINE search was supplemented by references from selected articles.

DATA SYNTHESIS:

Numerous experimental, epidemiologic, and clinical studies suggest that NSAIDs have promise as anticancer agents. The mechanism by which NSAIDs lead to decreased colon carcinogenesis is not fully understood, but may involve restoration of apoptosis and inhibition of prostaglandin-mediated angiogenesis. Compelling evidence from many observational studies has consistently documented a 40–50% reduction in the risk of adenomatous polyps, colorectal cancer incidence, and mortality in patients using NSAIDs. Recent randomized, controlled trials have demonstrated a benefit with aspirin in reducing the rate of development of new or recurrent adenomas in high-risk patients. In addition, randomized studies using sulindac and celecoxib in patients with FAP have documented significant regression of existing adenomatous polyps.

CONCLUSIONS:

Inhibition of COX-2 is an example of a targeted approach to the chemoprevention of colorectal cancer. However, controversy exists about the safety, efficacy, and optimal treatment regimen of NSAIDs as long-term chemopreventive agents in the general population. Ongoing studies in high-risk patients with both selective and nonselective COX inhibitors will provide important information in the area of colorectal chemoprevention, but clinical trials' use of adenomas as surrogate markers for chemoprevention trials makes their application to the general population limited.

S100A4 in Cancer Metastasis: Wnt Signaling-Driven Interventions for Metastasis Restriction

The aberrant activity of Wnt signaling is an early step in the transformation of normal intestinal cells to malignant tissue, leading to more aggressive tumors, and eventually metastases. In colorectal cancer (CRC), metastasis accounts for about 90% of patient deaths, representing the most lethal event during the course of the disease and is directly linked to patient survival, critically limiting successful therapy. This review focuses on our studies of the metastasis-inducing gene S100A4, which we identified as transcriptional target of β-catenin. S100A4 increased migration and invasion in vitro and metastasis in mice. In patient CRC samples, high S100A4 levels predict metastasis and reduced patient survival. Our results link pathways important for tumor progression and metastasis: the Wnt signaling pathway and S100A4, which regulates motility and invasiveness. S100A4 suppression by interdicting Wnt signaling has potential for therapeutic intervention. As proof of principle, we applied S100A4 shRNA systemically and prevented metastasis in mice. Furthermore, we identified small molecule inhibitors from high-throughput screens of pharmacologically active compounds employing an S100A4 promoter-driven reporter. Best hits act, as least in part, via intervening in the Wnt pathway and restricted metastasis in mouse models. We currently translate our findings on restricting S100A4-driven metastasis into clinical practice. The repositioned FDA-approved drug niclosamide, targeting Wnt signaling, is being tested in a prospective phase II clinical trial for treatment of CRC patients. Our assay for circulating S100A4 transcripts in patient blood is used to monitor treatment success.

Chemoprevention of hereditary colon cancers: time for new strategies

Colorectal cancer (CRC) is potentially preventable. Chemoprevention, a focus of research for the past three decades, aims to prevent or delay the onset of cancer through the regression or prevention of colonic adenomas. Ideal pharmacological agents for chemoprevention should be cheap and nontoxic. Although data indicate that aspirin can reduce the risk of CRC in the general population, the highest return from chemopreventive strategies would be expected in patients with the highest risk of developing the disease, particularly those with a defined hereditary predisposition. Despite compelling data showing that a large number of chemopreventive agents show promise in preclinical CRC models, clinical studies have yielded conflicting results. This Review provides a historical and methodological perspective of chemoprevention in familial adenomatous polyposis and Lynch syndrome, and summarizes the current status of CRC chemoprevention in humans. Our goal is to critically focus on important issues of trial design, with particular attention on the choice of appropriate trial end points, how such end points should be measured, and which patients are the ideal candidates to be included in a chemopreventive trial.

Multistage vector delivery of sulindac and silymarin for prevention of colon cancer

Familial adenomatous polyposis (FAP) is an inherited condition secondary to germline mutations in the APC gene, thus resulting in the formation of hundreds of colonic adenomas that eventually progress into colon cancer. Surgical removal of the colon remains the only treatment option to avoid malignancy, as long-term exposure to chemopreventive agents such as sulindac (a non-steroidal anti-inflammatory drug) and silymarin (phytoestrogen) is not feasible. Here, we have developed a multistage silicon-based drug delivery platform for sulindac and silymarin that preferentially interacts with colon cancer cells as opposed to normal intestinal mucosa. Preferential binding and internalization of these drugs into colon cancer cells was obtained using a targeting strategy against the protein meprin A, which we demonstrate is overexpressed in human colon cancer cells and in the small intestine of Apc(Min/+) mice. We propose that this delivery system could potentially be used to reduce drug-induced side effects in FAP patients, thus enabling long-term prevention of adenoma formation.

Inflammation and cancer: advances and new agents

Tumour-promoting inflammation is considered one of the enabling characteristics of cancer development. Chronic inflammatory disease increases the risk of some cancers, and strong epidemiological evidence exists that NSAIDs, particularly aspirin, are powerful chemopreventive agents. Tumour microenvironments contain many different inflammatory cells and mediators; targeting these factors in genetic, transplantable and inducible murine models of cancer substantially reduces the development, growth and spread of disease. Thus, this complex network of inflammation offers targets for prevention and treatment of malignant disease. Much potential exists in this area for novel cancer prevention and treatment strategies, although clinical research to support targeting of cancer-related inflammation and innate immunity in patients with advanced-stage cancer remains in its infancy. Following the initial successes of immunotherapies that modulate the adaptive immune system, we assert that inflammation and innate immunity are important targets in patients with cancer on the basis of extensive preclinical and epidemiological data. The adaptive immune response is heavily dependent on innate immunity, therefore, inhibiting some of the tumour-promoting immunosuppressive actions of the innate immune system might enhance the potential of immunotherapies that activate a nascent antitumour response.

NOSH-sulindac (AVT-18A) is a novel nitric oxide- and hydrogen sulfide-releasing hybrid that is gastrointestinal safe and has potent anti-inflammatory, analgesic, antipyretic, anti-platelet, and anti-cancer properties

Sulindac is chemopreventive and has utility in patients with familial adenomatous polyposis; however, side effects preclude its long-term use. NOSH-sulindac (AVT-18A) releases nitric oxide and hydrogen sulfide, was designed to be a safer alternative. Here we compare the gastrointestinal safety, anti-inflammatory, analgesic, anti-pyretic, anti-platelet, and anti-cancer properties of sulindac and NOSH-sulindac administered orally to rats at equimolar doses. Gastrointestinal safety: 6h post-administration, number/size of hemorrhagic lesions in stomachs were counted. Tissue samples were frozen for PGE2, SOD, and MDA determination. Anti-inflammatory: 1h after drug administration, the volume of carrageenan-induced rat paw edemas was measured for 5h. Anti-pyretic: fever was induced by LPS (ip) an hour before administration of the test drugs, core body temperature was measured hourly for 5h. Analgesic: time-dependent analgesic effects were evaluated by carrageenan-induced hyperalgesia. Antiplatelet: anti-aggregatory effects were studied on collagen-induced platelet aggregation of human platelet-rich plasma. Anti-cancer: We examined the effects of NOSH-sulindac on the growth properties of 12 human cancer cell lines of six different tissue origins. Both agents reduced PGE2 levels in stomach tissue; however, NOSH-sulindac did not cause any stomach ulcers, whereas sulindac caused significant bleeding. Lipid peroxidation induced by sulindac was higher than that from NOSH-sulindac. SOD activity was significantly lowered by sulindac but increased by NOSH-sulindac. Both agents showed similar anti-inflammatory, analgesic, anti-pyretic, and anti-platelet activities. Sulindac increased plasma TNFα whereas this rise was lower in the NOSH-sulindac-treated animals. NOSH-sulindac inhibited the growth of all cancer cell lines studied, with potencies of 1000- to 9000-fold greater than that of sulindac. NOSH-sulindac inhibited cell proliferation, induced apoptosis, and caused G2/M cell cycle block. These results demonstrate that NOSH-sulindac is gastrointestinal safe, and maintains the anti-inflammatory, analgesic, antipyretic, and antiplatelet properties of its parent compound sulinsac, with anti-growth activity against a wide variety of human cancer cells.

Senescence-associated inflammatory responses: aging and cancer perspectives

Senescent cells, albeit not proliferating, are metabolically and transcriptionally active, thereby capable of affecting their microenvironment, notably via the production of inflammatory mediators. These mediators maintain and propagate the senescence process to neighboring cells, and then recruit immune cells for clearing senescent cells. Among the inflammatory cues are molecules with pronounced tumor-controlling properties, both growth and invasion factors and inhibitory factors, working directly or via recruited immune cells. These senescence-inflammatory effects also prevail within tumors, mediated by the senescent tumor cells and the senescent tumor stroma. Here, we review the course and impact of senescence-associated inflammatory responses in aging and cancer. We propose that controlling senescence-associated inflammation by targeting specific inflammatory mediators may have a beneficial therapeutic effect in treatment of cancer and aging-related diseases.

Lack of significant association between serum inflammatory cytokine profiles and the presence of colorectal adenoma

Background

Inflammatory cytokines in the colonic microenvironment have been shown to increase with advance colorectal cancer disease state. However, the contribution of inflammatory cytokines to pre-malignant disease, such as the formation of adenomas, is unclear.

Methods

Using the Milliplex® MAP Human Cytokine/ Chemokine Magnetic Bead Panel Immunoassay, serum cytokine and chemokine profiles were assayed among participants without an adenoma (n = 97) and those with an adenoma (n = 97) enrolled in the NCI-funded Insulin Resistance Atherosclerosis Colon Study. The concentrations of interleukin-10 (IL-10), IL-1β, IL-6, IL-17A, IL-2, IL-4, IL-7, IL-12(p70), interferon-γ (IFN-γ), macrophage chemoattractant protein-1 (MCP-1), regulated on activation, normal T cell expressed and secreted (RANTES), tumor necrosis factor-alpha (TNF-α), vascular endothelial growth factor (VEGF), granulocyte macrophage colony-stimulating factor (GM-CSF), and macrophage inflammatory protein-1β (MIP-1β) were determined. Multiple logistic regression analyses were used to evaluate the association between adenoma prevalence and cytokine levels.

Results

The presence of colorectal adenomas was not associated with significant increases in the systemic levels of proinflammatory (TNF-α, IL-6, IL-1β) or T-cell polarizing (IL-12, IL-2, IL-10, IL-4, IL-17, IFN-γ) cytokines. Furthermore, MCP-1 and RANTES levels were equivalent in the serum of study participants with and without adenomas.

Conclusions

These findings suggest colorectal adenoma prevalence may not be associated with significant alterations in systemic inflammation.

Regression of Colonic Adenomas After Treatment With Sulindac in Familial Adenomatous Polyposis: A Case With a 2-Year Follow-up Without a Prophylactic Colectomy

Familial adenomatous polyposis (FAP) is an autosomal dominant disorder characterized by hundreds of colorectal adenomatous polyps that progress to colorectal cancer. Management of patients with FAP is with a total colectomy. Chemopreventive strategies have been studied in FAP patients in an effort to delay the development of adenomas in the upper and the lower gastrointestinal tract and to prevent recurrence of adenomas in the retained rectum of patients after prophylactic surgery. Sulindac, a nonsteroidal anti-inflammatory drug, causes regression of colorectal adenomas in the retained rectal segment of FAP patients. However, evidence regarding long-term use of this therapy and its effect on the intact colon has been insufficient. We report a case in which the long-term use of sulindac was effective in reducing the size and the number of colonic polyps in patients with FAP without a prophylactic colectomy and polypectomy; we also present a review of the literature.

A phase Ib study of the effects of black raspberries on rectal polyps in patients with familial adenomatous polyposis

Familial adenomatous polyposis (FAP) is characterized by the early onset of colonic polyposis and a high risk for colorectal cancer. FAP is treated by colectomy followed by lifelong removal of rectal polyps. This study determined whether black raspberries (BRBs) might regress rectal polyps in patients with FAP. Fourteen patients with FAP were treated with BRBs daily for 9 months. Seven patients received BRB powder orally plus two BRB suppositories inserted into the rectum at bedtime. The other 7 received an oral placebo plus the suppositories. Rectal polyp counts and polyp sizes were obtained at time zero and after 9 months of BRB treatment. Polyps and adjacent normal tissue were collected at both time points. The burden (P = 0.036) but not number (P = 0.069) of rectal polyps was significantly decreased. No benefit was noted with the addition of oral BRBs. Three patients were nonresponders. BRBs significantly decreased cellular proliferation, DNA methylation methyl transferase 1 protein expression, and p16 promoter methylation, but not promoter methylation of the Wnt pathway antagonists, SFRP2 and WIF1, in rectal polyps (adenomas) from responders but not from nonresponders. The MBD-seq assay revealed more demethylated transcription start sites (TSS), including those for miRNAs, in BRB-treated adenomas from the responders. In conclusion, BRB suppositories seem sufficient for regressing rectal polyps in patients with FAP.

Prevention and treatment of cancer with aspirin: where do we stand?

Aspirin is arguably the synthesized drug that has been used most commonly in human history. Aspirin was originally developed and marketed for the treatment of inflammatory disorders at the end of the 19th century, but its mechanism of action remained unknown until the second half of the 20th century. Since the latter part of the 20th century aspirin also has been used for the primary and secondary prevention of cardiovascular diseases given its anti-thrombotic properties. An association between intake of aspirin and decreased cancer risk was identified in the past decades. Whether aspirin can be used as an anticancer agent in patients with a diagnosis of cancer was unknown until recently. Recent studies suggest that aspirin might provide therapeutic benefit in the adjuvant treatment of certain forms of cancer. This review provides a critical update on this topic, which has potential implications for oncologists and their patients.

Sulindac compounds facilitate the cytotoxicity of β-lapachone by up-regulation of NAD(P)H quinone oxidoreductase in human lung cancer cells

β-lapachone, a major component in an ethanol extract of Tabebuia avellanedae bark, is a promising potential therapeutic drug for various tumors, including lung cancer, the leading cause of cancer-related deaths worldwide. In the first part of this study, we found that apoptotic cell death induced in lung cancer cells by high concentrations of β-lapachone was mediated by increased activation of the pro-apoptotic factor JNK and decreased activation of the cell survival/proliferation factors PI3K, AKT, and ERK. In addition, β-lapachone toxicity was positively correlated with the expression and activity of NAD(P)H quinone oxidoreductase 1 (NQO1) in the tumor cells. In the second part, we found that the FDA-approved non-steroidal anti-inflammatory drug sulindac and its metabolites, sulindac sulfide and sulindac sulfone, increased NQO1 expression and activity in the lung adenocarcinoma cell lines CL1-1 and CL1-5, which have lower NQO1 levels and lower sensitivity to β-lapachone treatment than the A549 cell lines, and that inhibition of NQO1 by either dicoumarol treatment or NQO1 siRNA knockdown inhibited this sulindac-induced increase in β-lapachone cytotoxicity. In conclusion, sulindac and its metabolites synergistically increase the anticancer effects of β-lapachone primarily by increasing NQO1 activity and expression, and these two drugs may provide a novel combination therapy for lung cancers.

The discovery and development of cyclooxygenase-2 inhibitors as potential anticancer therapies

INTRODUCTION

In the past, clinical studies had demonstrated that aspirin and NSAIDs reduce the risk of colorectal cancer. After the discovery of selective prostaglandin-endoperoxide synthase 2 (PTGS2) inhibitors, the further beneficial effects of celecoxib and some other related structures (coxibs) have been demonstrated in both in vivo and in vitro studies.

AREAS COVERED

The authors illustrate the role of prostaglandins following the overexpression of PTGS2 (COX-2) in signaling pathways. The authors elucidate the role of coxibs in cell proliferation, apoptosis, angiogenesis and multi-drug resistance and discuss the molecular mechanisms involved. The authors also present the strong evidence related to the usefulness of coxibs in several cancer cell lines.

EXPERT OPINION

There have been a number of PTGS2 (COX-2) selective inhibitors suggested as potential anticancer therapies. In recent years, the development of nanotechnology has also had an impact on chemotherapy. Indeed, nanoparticles of cytotoxic drug carriers have demonstrated potential through their accumulation in cancer cells, and targeting these nanoparticles has been under evaluation. This area could be opened up for coxib development as they are potentially important targets in cancer cells. Further research using celecoxib as a co-drug with PTGS2-overexpressed and PTGS2-independent cancer is still needed.

NSAIDs inhibit tumorigenesis, but how?

Numerous epidemiologic studies have reported that the long-term use of nonsteroidal anti-inflammatory drugs (NSAID) is associated with a significant decrease in cancer incidence and delayed progression of malignant disease. The use of NSAIDs has also been linked with reduced risk from cancer-related mortality and distant metastasis. Certain prescription-strength NSAIDs, such as sulindac, have been shown to cause regression of precancerous lesions. Unfortunately, the extended use of NSAIDs for chemoprevention results in potentially fatal side effects related to their COX-inhibitory activity and suppression of prostaglandin synthesis. Although the basis for the tumor growth-inhibitory activity of NSAIDs likely involves multiple effects on tumor cells and their microenvironment, numerous investigators have concluded that the underlying mechanism is not completely explained by COX inhibition. It may therefore be possible to develop safer and more efficacious drugs by targeting such COX-independent mechanisms. NSAID derivatives or metabolites that lack COX-inhibitory activity, but retain or have improved anticancer activity, support this possibility. Experimental studies suggest that apoptosis induction and suppression of β-catenin-dependent transcription are important aspects of their antineoplastic activity. Studies show that the latter involves phosphodiesterase inhibition and the elevation of intracellular cyclic GMP levels. Here, we review the evidence for COX-independent mechanisms and discuss progress toward identifying alternative targets and developing NSAID derivatives that lack COX-inhibitory activity but have improved antineoplastic properties.

Occult progression by Apc-deficient intestinal crypts as a target for chemoprevention

Although Apc mutation is widely considered an initiating event in colorectal cancer, little is known about the earliest stages of tumorigenesis following sporadic Apc loss. Therefore, we have utilized a novel mouse model that facilitates the sporadic inactivation of Apc via frameshift reversion of Cre in single, isolated cells and subsequently tracks the fates of Apc-deficient intestinal cells. Our results suggest that consistent with Apc being a 'gatekeeper', loss of Apc early in life during intestinal growth leads to adenomas or increased crypt fission, manifested by fields of mutant but otherwise normal-appearing crypts. In contrast, Apc loss occurring later in life has minimal consequences, with mutant crypts being less prone to either increased crypt fission or adenoma formation. Using the stem cell-specific Lgr5-CreER mouse, we generated different sized fields of Apc-deficient crypts via independent recombination events and found that field size correlates with progression to adenoma. To evaluate this early stage prior to adenoma formation as a therapeutic target, we examined the chemopreventive effects of sulindac on Apc-deficient occult crypt fission. We found that sulindac treatment started early in life inhibits the morphologically occult spread of Apc-deficient crypts and thus reduces adenoma numbers. Taken together these results suggest that: (i) earlier Apc loss promotes increased crypt fission, (ii) a field of Apc-deficient crypts, which can form via occult crypt fission or independent neighboring events, is an important intermediate between loss of Apc and adenoma formation and (iii) normal-appearing Apc-deficient crypts are potential unappreciated targets for cancer screening and chemoprevention.

COX-Independent Mechanisms of Cancer Chemoprevention by Anti-Inflammatory Drugs

Epidemiological and clinical studies suggest that non-steroidal anti-inflammatory drugs (NSAIDs), including cyclooxygenase (COX)-2 selective inhibitors, reduce the risk of developing cancer. Experimental studies in human cancer cell lines and rodent models of carcinogenesis support these observations by providing strong evidence for the antineoplastic properties of NSAIDs. The involvement of COX-2 in tumorigenesis and its overexpression in various cancer tissues suggest that inhibition of COX-2 is responsible for the chemopreventive efficacy of these agents. However, the precise mechanisms by which NSAIDs exert their antiproliferative effects are still a matter of debate. Numerous other studies have shown that NSAIDs can act through COX-independent mechanisms. This review provides a detailed description of the major COX-independent molecular targets of NSAIDs and discusses how these targets may be involved in their anticancer effects. Toxicities resulting from COX inhibition and the suppression of prostaglandin synthesis preclude the long-term use of NSAIDs for cancer chemoprevention. Furthermore, chemopreventive efficacy is incomplete and treatment often leads to the development of resistance. Identification of alternative NSAID targets and elucidation of the biochemical processes by which they inhibit tumor growth could lead to the development of safer and more efficacious drugs for cancer chemoprevention.

Systemic treatment for hereditary cancers: a 2012 update

The history of specific therapy for hereditary tumors dates back to mid 1980s and involves a number of reports demonstrating regression of familial colon polyps upon administration of sulindac. Virtually no clinical studies on other hereditary cancer types were available until the year 2009, when Byrski et al. presented the data on unprecedented sensitivity of BRCA1-associated breast malignancies to cisplatin. This breakthrough has revived interest to the treatment of cancer in germ-line mutation carriers. Recent trials and clinical observations have confirmed the efficacy of platinating agents and PARP inhibitors in BRCA1/2-driven breast, ovarian and pancreatic carcinomas. Pegylated liposomal doxorubicin may be considered as a promising treatment option for BRCA1/2-related ovarian cancer after the failure of platinum-containing therapy. Several novel drugs have been recently introduced in the management of rare familial tumor syndromes. Vandetanib, a low-molecular weight RET kinase inhibitor, demonstrated substantial efficacy in the treatment of hereditary and sporadic medullary thyroid cancer. Vismodegib, an inhibitor of SMO oncoprotein, caused regression of basal-cell carcinomas in patients with Gorlin syndrome. Down-regulation of mTOR kinase by everolimus has been successfully used for the therapy of subependymal giant-cell astrocytomas in patients with tuberous sclerosis. The achievements in the prevention, diagnostics and treatment of hereditary cancers may serve as an excellent example of triumph of translational medicine.

LGR5 promotes survival in human colorectal adenoma cells and is upregulated by PGE2: implications for targeting adenoma stem cells with NSAIDs

Cyclooxygenase-2 is overexpressed in the majority of colorectal tumours leading to elevated levels of prostaglandin E2 (PGE2), promoting many hallmarks of cancer. Importantly, PGE2 is reported to enhance Wnt/β-catenin signalling in colorectal carcinoma cells and in normal haematopoietic stem cells where it promotes stem cell function. Although Wnt signalling plays a crucial role in intestinal stem cells, the relationship between PGE2 and intestinal stem cells is unclear. Given that the key intestinal cancer stem cell marker LGR5 (leucine-rich G-protein coupled receptor 5) is a Wnt target and PGE2 enhances Wnt signalling, the focus of this study was to investigate whether PGE2 regulated LGR5 expression in colorectal adenoma cells and whether LGR5 was important for tumour cell survival. PGE2 upregulated LGR5 protein in adenoma (RG/C2) and carcinoma (DLD-1) cell lines. LGR5 knockdown induced cell death in RG/C2 and AA/C1 adenoma cells, suggesting that LGR5 has an important survival-promoting role in adenoma cells. Indeed, we detected LGR5 protein expression in 4 of 4 human adenoma cell lines. Furthermore, LGR5 small interfering RNA inhibited the survival-promoting effects of PGE2 in RG/C2, suggesting that PGE2 promotes adenoma cell survival, at least in part, by increasing LGR5 expression. These studies, therefore, show the first link between PGE2 and LGR5 in human colorectal adenoma and carcinoma cells and demonstrate a survival-promoting role of LGR5. As non-steroidal anti-inflammatory drugs (NSAIDs) cause adenomas to regress in FAP patients, these studies could have important implications for the mechanism by which NSAIDs are chemopreventive, as lowering PGE2 levels could reduce LGR5 expression and survival of LGR5(+) adenoma stem cells.

The anticancer effect of phospho-tyrosol-indomethacin (MPI-621), a novel phosphoderivative of indomethacin: in vitro and in vivo studies

We have synthesized a novel derivative of indomethacin, phospho-tyrosol-indomethacin (PTI; MPI-621), and evaluated its anticancer efficacy in vitro and in vivo. PTI inhibited the growth of human colon, breast and lung cancer cell lines 6-30-fold more potently than indomethacin. In vivo, in contrast to indomethacin that was unable to inhibit colon cancer xenograft growth, PTI inhibited the growth of colon (69% at 10mg/kg/day, P < 0.01) and lung (91% at 15mg/kg/day, P < 0.01) subcutaneous cancer xenografts in immunodeficient mice, suppressing cell proliferation by 33% and inducing apoptosis by 75% (P < 0.05, for both). Regarding its pharmacokinetics in mice, after a single intraperitoneal injection of PTI, its plasma levels reached the maximum concentration (Cmax = 46 μM) at 2h (Tmax) and became undetectable at 4h. Indomethacin is the major metabolite of PTI, with plasma Cmax = 378 μM and Tmax = 2.5h; it became undetectable 24h postadministration. The cellular uptake of PTI (50-200 μM) at 6h was about 200-fold greater than that of indomethacin. Regarding its safety, PTI had no significant genotoxicity, showed less gastrointestinal toxicity than indomethacin and presented no cardiac toxicity. Mechanistically, PTI suppressed prostaglandin E2 production in A549 human lung cancer cells and strongly inhibited nuclear factor-κB activation in A549 xenografts. These findings indicate that PTI merits further evaluation as an anticancer agent.

11β-Hydroxysteroid Dehydrogenase Type II is a Potential Target for Prevention of Colorectal Tumorigenesis

Colorectal cancer (CRC) is a leading cause of cancer death, yet primary prevention remains the best approach to reducing overall morbidity and mortality. There is a clear molecular link between cyclooxygenase-2 (COX-2)-derived prostaglandin E₂ (PGE₂) production and CRC progression. Although selective COX-2 inhibitors as well as non-steroidal anti-inflammatory drugs (NSAIDs) reduce the number and sizes of colonic adenomas, increased cardiovascular risks of selective COX-2 inhibitors and increased gastrointestinal side-effects of NSAIDs limit their use in chemoprevention of CRC. Glucocorticoids induce apoptosis and are endogenous, potent COX-2 inhibitors. Glucocorticoids have been used for the treatment of hematologic malignancies, but not for solid tumors due to adverse side-effects such as immunosuppression and osteoporosis. In tissues, glucocorticoid actions are down-regulated by t y p e 2 1 1 β-hydroxysteroid dehydrogenase (11βHSD2), and inhibition of 11βHSD2 activity will elevate intracellular active glucocorticoid to levels that effectively suppress COX-2 expression. Both COX-2 and 11βHSD2 increase in Apc^+/min mouse intestinal adenomas and human colonic adenomas and either pharmacologic or genetic 11βHSD2 inhibition leads to decreases in COX-2-mediated PGE₂ production in tumors and prevents adenoma formation, tumor growth, and metastasis. 11βHSD2 inhibition may represent a novel approach for CRC chemoprevention by increasing tumor cell intracellular glucocorticoid activity, which in turn inhibits tumor growth by suppressing the COX-2-derived PGE₂ pathway, as well as other pathways, without potential side-effects relating to chronic application of COX-2 inhibitors, NSAIDs and glucocorticoids.

The role of anti-inflammatory drugs in colorectal cancer

A large body of evidence indicates that genetic mutations, epigenetic changes, chronic inflammation, diet, and lifestyle are key risk factors for colorectal cancer (CRC). Prevention of CRC has long been considered a plausible approach for the population and individuals at high risk for developing this disease. A significant effort has been made in the development of novel drugs for both prevention and treatment over the past two decades. This review highlights recent advances in our understanding of the role of nonsteroidal anti-inflammatory drugs in CRC prevention and adjuvant treatment. Moreover, we focus on the molecular mechanisms underlying the antitumor effects of these drugs in CRC. The knowledge of how anti-inflammatory agents inhibit cancer formation and progression may provide a rationale for the development of more effective chemopreventive and chemotherapeutic agents with less toxicity.

Multifaceted roles of PGE2 in inflammation and cancer

Prostaglandin E(2) (PGE(2)) is a bioactive lipid that elicits a wide range of biological effects associated with inflammation and cancer. PGE(2) exerts diverse effects on cell proliferation, apoptosis, angiogenesis, inflammation, and immune surveillance. This review concentrates primarily on gastrointestinal cancers, where the actions of PGE(2) are most prominent, most likely due to the constant exposure to dietary and environmental insults and the intrinsic role of PGE(2) in tissue homeostasis. A discussion of recent efforts to elucidate the complex and interconnected pathways that link PGE(2) signaling with inflammation and cancer is provided, supported by the abundant literature showing a protective effect of NSAIDs and the therapeutic efficacy of targeting mPGES-1 or EP receptors for cancer prevention. However, suppressing PGE(2) formation as a means of providing chemoprotection against all cancers may not ultimately be tenable, undoubtedly the situation for patients with inflammatory bowel disease. Future studies to fully understand the complex role of PGE(2) in both inflammation and cancer will be required to develop novel strategies for cancer prevention that are both effective and safe.