Chemoprevention Of Colorectal Cancer Research Articles

Antiproliferative and Morphological Effects of Fenretinide Lipid Nanosystems in Colon Adenocarcinoma Cells.

Objective: Colon adenocarcinoma is characterized by the downregulation of the retinoic acid receptor, making natural retinoids such as all-trans retinoic acid, 9-cis retinoic acid and 13-cis retinoic acid effective in treatment and chemoprevention due to their ability to increase RARβ expression. However, major limitations to their use include tolerability and acquired resistance. In this study, we evaluated fenretinide, a semisynthetic derivative of all-trans retinoic acid, in an HT-29 cell line. Fenretinide was evaluated both as a free drug and encapsulated in self-assembling phosphatidylcholine nanosystems with the aim of increasing the aqueous solubility and cell availability of the drug. Methods: Fenretinide was encapsulated in lipid nanosystems obtained in water by the dispersion of an amphiphilic mixture of phospholipids, glyceryl tributyrate and polysorbate 80. The physico-chemical characterization of the nanosystems was carried out by dynamic light scattering and spectrophotometry. The biological activity was evaluated by quantitative phase imaging microscopy, MTT assay, flow cytometry and confocal laser-scanning fluorescence microscopy. Results: Fenretinide in phosphatidylcholine nanosystems was more active than free fenretinide in inhibiting HT-29 cells' proliferation, as indicated by quantitative phase imaging data. Indeed, encapsulated fenretinide increased duplication time, decreased dry mass and decreased the rate of cell growth more efficiently than fenretinide. Moreover, encapsulated fenretinide effectively decreased the motility of the cells that survived the treatment. Conclusions: The results indicate that the proposed nanosystems can be considered a valuable alternative to natural retinoids in the chemoprevention and treatment of colorectal cancer. This is due to the favorable pharmacologic characteristics of fenretinide in colorectal cancer and the improved drug activity provided by nanoencapsulation.

Antiviral and Cytotoxic Activities of Ilex aquifolium Silver Queen in the Context of Chemical Profiling of Two Ilex Species.

The leaves of Ilex paraguariensis (known as Yerba mate), used as a popular beverage, are a very well-recognized plant material with various biological activities, including analeptic (because of caffeine), anti-obesity (phenolics, saponins), antimicrobial, and antiviral (phenolics, saponins). Here, the chemical compositions of the leaves of two European Ilex species (× meserveae and aquifolium) with three varieties each were investigated. The terpenoid, saponin, and polyphenolic fractions were submitted for LC-MS or GC-MS analysis against a standard Mate leaf. In addition, the aroma profiles of all the species were analysed using HS-SPME-Arrow prior to GC-MS analysis. All fractions were subjected to antiviral and cytotoxic assays. We found 86 compounds in all accessions, with limonene, linalool, and p-cymene being predominant. There were minor similarities between the volatile compositions of the European and South American species. We found ursolic and oleanolic acid to be the main compounds in the terpenoid fraction. Mono-caffeoylquinic acids and di-caffeoylquinic acids were the main constituents of the polar fractions. About 180 compounds from the saponin group were tentatively identified, of which 9 and 3 were selected as distinctive markers for I. meserveae and I. aquifolium, respectively. Based on chemical screening, I. aquifolium Silver Queen was chosen as the source of terpenoid and saponin fractions and polyphenol extracts. The most substantial inhibition of cancer cell growth was observed with saponin in the case of the MCF7 (human breast cancer) cell line, while for LoVo and L929 cell lines (human colorectal cancer and reference mouse fibroblasts), it was slightly weaker. These results should be analysed further as a promising chemoprevention of colorectal and gastrointestinal cancers. Saponin and polyphenolic extracts exhibited similar activities against HSV-1 and HAdV-5, with 4-log reduction in virus titres. This study focuses our attention on a field of potential antiviral formulations derived from European holly.

In vitro anticancer, antioxidant, cytotoxic activity and phytochemical characterization of Inula viscosa L. essential oil against colorectal cancer cell line HCT-116

Human colorectal cancer cell line (HCT116) cells are adherent epithelial cells derived from the human colorectal carcinoma cell line commonly used to study inflammatory responses in colonic epithelial cells. This study aimed to evaluate the protective effects of Inula viscosa essential oil (IVEO), an effective antioxidant compound with a radical scavenging activity in vitro using HCT-116 cells. The chemical composition of hydrodistilled IVEO was analyzed by GC-FID and GC-MS systems. The major compounds of essential oil were borneol acetate (51.54%) and borneol (21.17%). The cytotoxicity was determined using the colorimetric MTT assay for 24 h, and 48 h. Malondialdehyde (MDA) level, some enzymes activities including catalase (CAT) and superoxide dismutase (SOD) were measured in the HCT 116 cells both with and without IVEO treatment. In this study, there was a significant decrease in activities of cellular SOD and CAT, increased in the MDA levels in the cells treated with IVEO. These result indicate that IVEO can serve as an agent with strong potential to be utilized for the development of colorectal cancer chemoprevention. However, further molecular investi-gation is required to understand the molecular bearings of IVEO.

Cost-Utility Analysis of Berberine Chemoprevention for Colorectal Cancer After Polypectomy.

Background Chemoprevention, such as berberine, has been developed as an alternative or complementary strategy to colonoscopy surveillance and has shown promise in reducing the morbidity and mortality of colorectal cancer. This study aims to evaluate the cost-effectiveness of berberine for postpolypectomy patients from the US third-party payer. Methods A Markov microsimulation model was developed to compare the cost and efficacy of berberine to no intervention, colonoscopy, and the combination of berberine and colonoscopy in postpolypectomy patients. Results After simulating 1 million patients, the study found that colonoscopy alone had a mean cost of $16,391 andmean quality-adjusted life-years (QALYs) of 16.03 per patient, whereas adding berberine slightly reduced the mean cost to $15,609 with a mean QALY of 16.05, making it a dominant strategy. Berberine therapy alone was less effective than colonoscopy alone, with a higher mean cost of $37,480 and a mean QALY of 15.32 per patient. However, berberine therapy was found to be a dominant strategy over no intervention. Conclusions Adding berberine to colonoscopy is the most cost-saving and effective approach for postpolypectomy patients. For patients who refuse or have limited access to colonoscopy, berberine alone is likely to be a dominant strategy compared to no intervention.

Harnessing Oxylipins and Inflammation Modulation for Prevention and Treatment of Colorectal Cancer.

Colorectal cancer (CRC) is one of the most prevalent cancers worldwide, ranking as the third most malignant. The incidence of CRC has been increasing with time, and it is reported that Westernized diet and lifestyle play a significant role in its higher incidence and rapid progression. The intake of high amounts of omega-6 (n - 6) PUFAs and low levels of omega-3 (n - 3) PUFAs has an important role in chronic inflammation and cancer progression, which could be associated with the increase in CRC prevalence. Oxylipins generated from PUFAs are bioactive lipid mediators and have various functions, especially in inflammation and proliferation. Carcinogenesis is often a consequence of chronic inflammation, and evidence has shown the particular involvement of n - 6 PUFA arachidonic acid-derived oxylipins in CRC, which is further described in this review. A deeper understanding of the role and metabolism of PUFAs by their modifying enzymes, their pathways, and the corresponding oxylipins may allow us to identify new approaches to employ oxylipin-associated immunomodulation to enhance immunotherapy in cancer. This paper summarizes oxylipins identified in the context of the initiation, development, and metastasis of CRC. We further explore CRC chemo-prevention strategies that involve oxylipins as potential therapeutics.

Abstract 7305: Chemoprevention of colorectal cancer: Role of trace minerals in conjunction with calcium

Abstract Background: Colorectal cancer (CRC) is a leading cause of cancer-related deaths worldwide. CRC usually develops from adenomas (CRC precursors) after a long latency period. Prevention is crucial in reducing CRC incidence and progression to cancer. Among several prevention options, calcium has been a widely considered chemo-preventative agent. Aims: Calcium plays a vital role in the regulation of epithelial cell differentiation, which is essential for epithelial growth control. Epidemiological studies have demonstrated that adequate calcium intake is crucial for protection against colonic polyp formation and colorectal cancer. However, recent interventional trials with calcium have had only modest and mixed results, and the question is how to improve efficacy. One potential strategy is to use calcium in combination with additional minerals and trace elements. Results: Our preclinical studies employing monolayer cultures with CRC cell lines and colon organoids cultures from colon polyps have shown that a calcium-rich mineral combination derived from fossilized red algae (Aquamin) is more effective than calcium alone in inducing differentiation, suppressing growth and upregulation of calcium-sensing receptor. When colonic adenomas in culture were subjected to differential proteomic analysis, Aquamin upregulated several proteins involved in proliferation suppression, DNA mismatch repair and inducing differentiation, and apoptosis. Two long-term mouse studies have demonstrated that Aquamin is more effective in suppressing polyp & CRC incidence compared to calcium alone. Based on these findings, we conducted a 90-day FDA-approved trial (a pilot study with ten subjects per arm) comparing the two interventions in human subjects at risk for CRC. Results showed that Aquamin treatment reduced proliferation and increased cell differentiation observed by immunohistochemistry. Proteomic analysis also revealed that the minerals upregulated several proteins related to growth suppression, inducing differentiation and those contributing to cell-cell and cell-matrix adhesion functions and downregulated proteins involved in proliferation and nucleic acid metabolism. Conclusion: These results provide convincing evidence that a multi-mineral combination derived from red algae can provide benefits in preventing CRC that are not seen with calcium alone. Further studies, such as a polyp-prevention trial in human subjects, are warranted to advance these CRC prevention efforts. Citation Format: Isabelle Harber, Shannon McClintock, James Varani, Muhammad N. Aslam. Chemoprevention of colorectal cancer: Role of trace minerals in conjunction with calcium [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 7305.

Morindone as a potential therapeutic compound targeting TP53 and KRAS mutations in colorectal cancer cells

There is an increasing demand for anticancer agent in treating colorectal cancer (CRC) with frequently mutated TP53 and KRAS genes. Phytochemical compounds are suitable as chemoprevention for CRC since dietary factor is a major risk factor. Anthraquinones from Morinda citrifolia L. were previously reported with various pharmacological properties. Various in vitro experiments were conducted to investigate the effects of two anthraquinones: damnacanthal and morindone on the cell proliferation, cell cycle, apoptosis, gene expression and protein expression in two CRC cells: HCT116 and HT29. Real-time monitoring of CRC cells showed that both anthraquinones exerted significant anti-proliferative effects in a dose- and time-dependent manner. Next, cell cycle analysis revealed an increase in the percentage of CRC cells in the G1 phase under anthraquinones treatment. Fluorescence microscopy also showed an increment of apoptotic cells under anthraquinones’ treatment. siRNA transfection was conducted to evaluate the mediating effect of gene knockdown on mutated TP53 and KRAS in CRC cells. Before transfection, qRT-PCR analysis showed that only morindone downregulated the gene expression of mutated TP53 and KRAS and then further downregulated them after transfection. Both damnacanthal and morindone treatments further downregulated the expression of these two genes but upregulated at the protein expression level. Furthermore, gene knockdown also sensitised CRC cells to both damnacanthal and morindone treatments, resulting in lowered IC50 values. The accumulation of cells at the G1 phase was reduced after gene knockdown but increased after damnacanthal and morindone treatments. In addition, gene knockdown has increased the number of apoptotic cells in both cell lines and further increment was observed after anthraquinone treatment. In conclusion, morindone could be a competitive therapeutic agent in CRC by exhibiting multiple mechanism of anti-cancer actions.

Thymoquinone: A Promising Therapeutic Agent for the Treatment of Colorectal Cancer.

Colorectal cancer (CRC) is one of the most commonly diagnosed cancers and is responsible for approximately one million deaths each year. The current standard of care is surgical resection of the lesion and chemotherapy with 5-fluorouracil (5-FU). However, of concern is the increasing incidence in an increasingly younger patient population and the ability of CRC cells to develop resistance to 5-FU. In this review, we discuss the effects of thymoquinone (TQ), one of the main bioactive components of Nigella sativa seeds, on CRC, with a particular focus on the use of TQ in combination therapy with other chemotherapeutic agents. TQ exhibits anti-CRC activity by inducing a proapoptotic effect and inhibiting proliferation, primarily through its effect on the regulation of signaling pathways crucial for tumor progression and oxidative stress. TQ can be used synergistically with chemotherapeutic agents to enhance their anticancer effects and to influence the expression of signaling pathways and other genes important in cancer development. These data appear to be most relevant for co-treatment with 5-FU. We believe that TQ is a suitable candidate for consideration in the chemoprevention and adjuvant therapy for CRC, but further studies, including clinical trials, are needed to confirm its safety and efficacy in the treatment of cancer.

Novel sulindac derivatives for colorectal cancer chemoprevention that target cGMP phosphodiesterases to suppress Wnt/β-catenin transcriptional activity

<p class="MsoNormal" style="margin-top: 6pt; line-height: 13pt; text-align: justify;"><span lang="EN-US" style="font-size: 10pt; font-family: arial, helvetica, sans-serif;">Approximately 28 million individuals in the United States face the risk of developing precancerous colonic adenomas (polyps) and potentially progressing to colorectal cancer (CRC). While a promising strategy for CRC prevention involves pharmacological intervention, such as cancer chemoprevention or interception, currently, there are no FDA-approved drugs capable of preventing the formation or progression of adenomas to adenocarcinoma. Numerous clinical, epidemiological, and preclinical studies have offered compelling evidence supporting the efficacy of nonsteroidal anti-inflammatory drugs (NSAIDs) in CRC chemoprevention. However, the prolonged use of NSAIDs is not FDA-approved due to potential life-threatening toxicities resulting from cyclooxygenase (COX) inhibition and the depletion of physiological prostaglandins. Despite indications that the COX inhibitory activity of NSAIDs may not be essential for their antineoplastic effects, the absence of a well-defined target impeded the development of derivatives that do not inhibit COX. Earlier research suggests that the inhibition of cyclic guanosine monophosphate phosphodiesterase (cGMP PDE) may be responsible, at least in part, for the antineoplastic activity of the NSAID sulindac. This could potentially offer a novel target for CRC chemoprevention. To identify the cGMP PDE isozyme(s) contributing to the antineoplastic activity of sulindac, we synthesized a chemically diverse library of over 1500 compounds, all sharing the indene scaffold of sulindac. Subsequently, we screened these compounds for their impact on cancer cell growth and PDE inhibitory activity. From this screening, a series of lead compounds emerged. These compounds lacked COX-1 and COX-2 inhibitory activity, surpassing sulindac in potency to inhibit CRC cell growth. Importantly, they demonstrated greater selectivity by not affecting normal cell growth. Through chemical optimization, we identified several development candidates that selectively inhibit PDE5 and/or PDE10. These compounds activate cGMP/PKG signaling, suppressing Wnt/β-catenin transcription. This action counters the growth advantages resulting from APC or CTNNB1 mutations, which are responsible for most human CRCs. This review delves into the scientific literature supporting PDE5 and/or PDE10 as potential targets for CRC chemoprevention or interception. Our findings suggest a promising avenue for developing drugs that may effectively intervene in the progression of colorectal cancer, offering hope for improved preventive strategies in the future.</span></p>

Novel sulindac derivatives for colorectal cancer chemoprevention that target cGMP phosphodiesterases to suppress Wnt/β-catenin transcriptional activity

<p class="MsoNormal" style="margin-top: 6pt; line-height: 13pt; text-align: justify;"><span lang="EN-US" style="font-size: 10pt; font-family: arial, helvetica, sans-serif;">Approximately 28 million individuals in the United States face the risk of developing precancerous colonic adenomas (polyps) and potentially progressing to colorectal cancer (CRC). While a promising strategy for CRC prevention involves pharmacological intervention, such as cancer chemoprevention or interception, currently, there are no FDA-approved drugs capable of preventing the formation or progression of adenomas to adenocarcinoma. Numerous clinical, epidemiological, and preclinical studies have offered compelling evidence supporting the efficacy of nonsteroidal anti-inflammatory drugs (NSAIDs) in CRC chemoprevention. However, the prolonged use of NSAIDs is not FDA-approved due to potential life-threatening toxicities resulting from cyclooxygenase (COX) inhibition and the depletion of physiological prostaglandins. Despite indications that the COX inhibitory activity of NSAIDs may not be essential for their antineoplastic effects, the absence of a well-defined target impeded the development of derivatives that do not inhibit COX. Earlier research suggests that the inhibition of cyclic guanosine monophosphate phosphodiesterase (cGMP PDE) may be responsible, at least in part, for the antineoplastic activity of the NSAID sulindac. This could potentially offer a novel target for CRC chemoprevention. To identify the cGMP PDE isozyme(s) contributing to the antineoplastic activity of sulindac, we synthesized a chemically diverse library of over 1500 compounds, all sharing the indene scaffold of sulindac. Subsequently, we screened these compounds for their impact on cancer cell growth and PDE inhibitory activity. From this screening, a series of lead compounds emerged. These compounds lacked COX-1 and COX-2 inhibitory activity, surpassing sulindac in potency to inhibit CRC cell growth. Importantly, they demonstrated greater selectivity by not affecting normal cell growth. Through chemical optimization, we identified several development candidates that selectively inhibit PDE5 and/or PDE10. These compounds activate cGMP/PKG signaling, suppressing Wnt/β-catenin transcription. This action counters the growth advantages resulting from APC or CTNNB1 mutations, which are responsible for most human CRCs. This review delves into the scientific literature supporting PDE5 and/or PDE10 as potential targets for CRC chemoprevention or interception. Our findings suggest a promising avenue for developing drugs that may effectively intervene in the progression of colorectal cancer, offering hope for improved preventive strategies in the future.</span></p>

Salicylate induces AMPK and inhibits c-MYC to activate a NRF2/ARE/miR-34a/b/c cascade resulting in suppression of colorectal cancer metastasis

Aspirin and its active metabolite salicylate have emerged as promising agents for the chemoprevention of colorectal cancer (CRC). Moreover, aspirin suppresses the progression of established CRCs. However, the underlying molecular mechanisms are not completely understood. Here we found that salicylate induces the expression of the miR-34a and miR-34b/c genes, which encode tumor suppressive microRNAs, in a p53-independent manner. Salicylate activated AMPK, thereby activating NRF2, which directly induced miR-34a/b/c expression via ARE motifs. In addition, salicylate suppressed c-MYC, a known repressor of NRF2-mediated transactivation, via activating AMPK. The suppression of c-MYC by salicylate was necessary for NRF2-mediated activation of miR-34a/b/c. Inactivation of miR-34a/b/c largely abrogated the inhibitory effects of salicylate on migration, invasion and metastasis formation by CRC cells. In the future, aspirin and its derivates may be used therapeutically to activate miR-34a and miR-34b/c in tumors that have lost p53.

The effect of aspirin and eicosapentaenoic acid on urinary biomarkers of prostaglandin E2 synthesis and platelet activation in participants of the seAFOod polyp prevention trial.

Urinary prostaglandin (PG) E metabolite (PGE-M) and 11-dehydro (d)-thromboxane (TX) B2 are biomarkers of cyclooxygenase-dependent prostanoid synthesis. We investigated (1) the effect of aspirin 300 mg daily and eicosapentaenoic acid (EPA) 2000 mg daily, alone and in combination, on urinary biomarker levels and, (2) whether urinary biomarker levels predicted colorectal polyp risk, during participation in the seAFOod polyp prevention trial. Urinary PGE-M and 11-d-TXB2 were measured by liquid chromatography-tandem mass spectrometry. The relationship between urinary biomarker levels and colorectal polyp outcomes was investigated using negative binomial (polyp number) and logistic (% with one or more polyps) regression models. Despite wide temporal variability in PGE-M and 11-d-TXB2 levels within individuals, both aspirin and, to a lesser extent, EPA decreased levels of both biomarkers (74% [P ≤ .001] and 8% [P ≤ .05] reduction in median 11-d-TXB2 values, respectively). In the placebo group, a high (quartile [Q] 2-4) baseline 11-d-TXB2 level predicted increased polyp number (incidence rate ratio [IRR] [95% CI] 2.26 [1.11,4.58]) and risk (odds ratio [95% CI] 3.56 [1.09,11.63]). A low (Q1) on-treatment 11-d-TXB2 level predicted reduced colorectal polyp number compared to placebo (IRR 0.34 [0.12,0.93] for combination aspirin and EPA treatment) compared to high on-treatment 11-d-TXB2 values (0.61 [0.34,1.11]). Aspirin and EPA both inhibit PGE-M and 11-d-TXB2 synthesis in keeping with shared in vivo cyclooxygenase inhibition. Colorectal polyp risk and treatment response prediction by 11-d-TXB2 is consistent with a role for platelet activation during early colorectal carcinogenesis. The use of urinary 11-d-TXB2 measurement for a precision approach to colorectal cancer risk prediction and chemoprevention requires prospective evaluation.

Polymorphisms in Cyclooxygenase, Lipoxygenase and TP53 genes predict colorectal polyp risk reduction by aspirin in the seAFOod polyp prevention trial.

Aspirin and eicosapentaenoic acid (EPA) reduce colorectal adenomatous polyp risk and affect synthesis of oxylipins including prostaglandin E2. We investigated whether 35 single nucleotide polymorphisms (SNPs) in oxylipin metabolism genes such as cyclooxygenase [PTGS] and lipoxygenase [ALOX], as well as 7 SNPs already associated with colorectal cancer (CRC) risk reduction by aspirin (eg. TP53; rs104522), modified the effects of aspirin and EPA on colorectal polyp recurrence in the randomised 2x2 factorial seAFOod trial. Treatment effects were reported as the incidence rate ratio (IRR) and 95% confidence interval (CI) by stratifying negative binomial and Poisson regression analyses of colorectal polyp risk on SNP genotype. Statistical significance was reported with adjustment for the false discovery rate as the P and q value. Five hundred and forty-two (of 707) trial participants had both genotype and colonoscopy outcome data. Reduction in colorectal polyp risk in aspirin users compared with non-aspirin users was restricted to rs4837960 (PTGS1) common homozygotes (IRR 0.69 [95%CI 0.53,0.90]; q=0.06), rs2745557 (PTGS2) compound heterozygote-rare homozygotes (IRR 0.60 [0.41,0.88]; q=0.06), rs7090328 (ALOX5) rare homozygotes (IRR 0.27 [0.11,0.64]; q=0.05), rs2073438 (ALOX12) common homozygotes (IRR 0.57 [0.41,0.80]; q=0.05), and rs104522 (TP53) rare homozygotes (IRR 0.37 [0.17,0.79]; q=0.06). No modification of colorectal polyp risk in EPA users was observed. In conclusion, genetic variants relevant to the proposed mechanism of action on oxylipins are associated with differential colorectal polyp risk reduction by aspirin in individuals who develop multiple colorectal polyps. SNP genotypes should be considered during development of personalised, predictive models of CRC chemoprevention by aspirin.

Bacterial nanocellulose spheres coated with meta acrylic copolymer: Vaccinium meridionale swartz extract delivery for colorectal cancer chemoprevention

Bacterial nanocellulose, a natural hydrocolloid traditionally used as food ingredient, has demonstrated potential as a non-soluble dietary fiber and functional material. Moreover, its properties can further be potentialized whether coupled with natural anthocyanins to endow antioxidant activity. Vaccinium meridionale swartz extract (VE), rich in anthocyanins, has recently demonstrated effects against colorectal cancer; therefore, encapsulating it into bacterial nanocellulose (BNC) may offer an enhanced VE delivery alternative. However, BNC has an open interconnected porosity that may generate a quick delivery of VE in gastric fluids impacting its stability. Accordingly, this paper explores meta-acrylic copolymer coatings of BNC spheres for VE delivery in a colorectal environment while potentially reducing its delivery in stomach conditions. The VE was characterized in terms of antioxidant capacity, colorectal cancer cell inhibition, and selectivity and then, it was incorporated into BNC spheres and coated with a meta-acrylic copolymer. The system's physicochemical, morphological, and delivery performance was studied under colonic and gastric conditions. Results show the coating's effectiveness in changing the VE delivery profile under colonic conditions and the potential of natural extracts for the selective inhibition of colorectal cancer cells (SW480 and SW620). The above results demonstrated that meta-acrylic copolymer-coated BNC spheres is a potential system for encapsulating natural extracts for colorectal cancer chemoprevention.

Regulation of Xenobiotic-Metabolizing Enzymes by 5-Demethylnobiletin and Nobiletin to Mitigate Benzo[a]pyrene-Induced DNA Damage In Vitro and In Vivo.

Benzo[a]pyrene (B[a]P) is a genotoxic polycyclic aromatic hydrocarbon that is metabolized by cytochrome P450 family 1 enzymes (CYP 1s) and can bind to DNA to form DNA adducts, leading to DNA damage and increased colorectal cancer risk. Previous studies have shown polymethoxyflavones to have a high potential for anticancer effects by regulating CYP 1s, especially nobiletin (NBT) and 5-demethylnobiletin (5-DMNB). However, the effects of NBT and 5-DMNB on B[a]P metabolism remain unclear. Therefore, this study aimed to clarify the effects of NBT and 5-DMNB on B[a]P-induced DNA damage in vitro and in vivo. In NCM460 cells, 5-DMNB and NBT appeared to reduce the metabolic conversion of B[a]P by regulating the aryl hydrocarbon receptor (AhR)/CYP 1s signaling pathway. This process protected NCM460 cells from B[a]P's cytotoxic effects by decreasing DNA damage and suppressing B[a]P diol-epoxide-DNA adduct formation. In BALB/c mice, 5-DMNB and NBT also protected against B[a]P-induced DNA damage. Altogether, these findings indicate that 5-DMNB and NBT attenuate B[a]P-induced DNA damage by modulating biotransformation, highlighting their chemopreventive potential against B[a]P-induced carcinogenesis. Therefore, 5-DMNB and NBT are promising agents for colorectal cancer chemoprevention in the future.

Aspirin chemoprevention in colorectal cancer: network meta-analysis of low, moderate, and high doses.

Colorectal cancer is the third most common cancer, with nearly 2 million cases worldwide and just under 1 million deaths in 2020. Several trials have demonstrated that aspirin has the potential to reduce the incidence and/or recurrence of colorectal cancer; however, the optimal aspirin dose is unclear. Relevant studies were identified by searching MEDLINE, Embase and the Cochrane Library from database inception to 2 February 2022. Data from RCTs in which the incidence of colorectal cancer in patients without active colorectal cancer assigned to aspirin versus control were included. Two investigators independently identified studies and abstracted data. Study quality was assessed using Cochrane Collaboration risk-of-bias 2 tool. The study was performed according to PRISMA guidelines. Aspirin dose was stratified into low (50-163 mg/day), mid (164-325 mg/day), and high (500-1200 mg/day). Thirteen articles representing 11 RCTs (92 550 participants) were included, with studies assessing aspirin as primary prophylaxis in general or high-risk populations, and as secondary prophylaxis for metachronous colorectal cancer. There was a statistically significant reduction in colorectal cancer incidence in the high-dose aspirin group compared with the group that received no aspirin or placebo (OR 0.69, 95 per cent credible interval 0.50 to 0.96; surface under the cumulative ranking 0.82). There was no statistically significant difference between mid- and low-dose aspirin versus no aspirin/placebo. In this network meta-analysis of RCTs, high-dose aspirin was associated with a reduction in colorectal cancer incidence. However, this was based on a limited number of trials. This study did not show a statistically significant risk reduction in colorectal cancer incidence with mid- or low-dose aspirin.

Colorectal Cancer Chemoprevention: A Dream Coming True?

Colorectal cancer (CRC) is one of the deadliest forms of cancer worldwide. CRC development occurs mainly through the adenoma-carcinoma sequence, which can last decades, giving the opportunity for primary prevention and early detection. CRC prevention involves different approaches, ranging from fecal occult blood testing and colonoscopy screening to chemoprevention. In this review, we discuss the main findings gathered in the field of CRC chemoprevention, focusing on different target populations and on various precancerous lesions that can be used as efficacy evaluation endpoints for chemoprevention. The ideal chemopreventive agent should be well tolerated and easy to administer, with low side effects. Moreover, it should be readily available at a low cost. These properties are crucial because these compounds are meant to be used for a long time in populations with different CRC risk profiles. Several agents have been investigated so far, some of which are currently used in clinical practice. However, further investigation is needed to devise a comprehensive and effective chemoprevention strategy for CRC.

Cyclooxygenase and Lipoxygenase Gene Expression in the Inflammogenesis of Colorectal Cancer: Correlated Expression of EGFR, JAK STAT and Src Genes, and a Natural Antisense Transcript, RP11-C67.2.2

We examined the expression of major inflammatory genes, cyclooxygenase-1, 2 (COX1, COX2), arachidonate-5-lipoxygenase (ALOX5), and arachidonate-5-lipoxygenase activating protein (ALOX5AP) among 469 tumor specimens of colorectal cancer in The Cancer Genome Atlas (TCGA). Among 411 specimens without mutations in mismatch repair (MMR) genes, the mean expression of each of the inflammatory genes ranked above the 80th percentile, and the overall mean cyclooxygenase expression (COX1+COX2) ranked in the upper 99th percentile of all genes. Similar levels were observed for 58 cases with MMR mutations. Pearson correlation coefficients exceeding r = 0.70 were observed between COX and LOX mRNA levels with genes of major cell-signaling pathways involved in tumorigenesis (Src, JAK STAT, MAPK, PI3K). We observed a novel association (r = 0.78) between ALOX5 expression and a natural antisense transcript (NAT), RP11-67C2.2, a long non-coding mRNA gene, 462 base pairs in length that is located within the terminal intron of the ALOX5 gene on chromosome 10q11.21. Tumor-promoting genes highly correlated with the expression of COX1, COX2, ALOX5 and ALOX5AP are known to increase mitogenesis, mutagenesis, angiogenesis, cell survival, immunosuppression and metastasis in the inflammogenesis of colorectal cancer. These genes and the novel NAT, RP1167C2.2 are potential molecular targets for chemoprevention and therapy of colorectal cancer.

Chemoprevention of colorectal cancer in general population and high-risk population: a systematic review and network meta-analysis.

Many nutritional supplements and pharmacological agents have been reported to show preventive effects on colorectal adenoma and colorectal cancer (CRC). We performed a network meta-analysis to summarize such evidence and assess the efficacy and safety of these agents. We searched PubMed, Embase, and the Cochrane Library for studies published in English until October 31, 2021 that fit our inclusion criteria. We performed a systematic review and network meta-analysis to assess the comparative efficacy and safety of candidate agents (low-dose aspirin [Asp], high-dose Asp, cyclooxygenase-2 inhibitors [coxibs], calcium, vitamin D, folic acid, ursodeoxycholic acid [UDCA], estrogen, and progesterone, alone or in combination) for preventing colorectal adenoma and CRC. Cochrane risk-of-bias assessment tool was employed to evaluate the quality of each included study. Thirty-two randomized controlled trials (278,694 participants) comparing 13 different interventions were included. Coxibs significantly reduced the risk of colorectal adenoma (risk ratio [RR]: 0.59, 95% confidence interval [CI]: 0.44-0.79, six trials involving 5486 participants), advanced adenoma (RR: 0.63, 95% CI: 0.43-0.92, four trials involving 4723 participants), and metachronous adenoma (RR: 0.58, 95% CI: 0.43-0.79, five trials involving 5258 participants) compared with placebo. Coxibs also significantly increased the risk of severe adverse events (RR: 1.29, 95% CI: 1.13-1.47, six trials involving 7109 participants). Other interventions, including Asp, folic acid, UDCA, vitamin D, and calcium, did not reduce the risk of colorectal adenoma in the general and high-risk populations compared with placebo. Considering the balance between benefits and harms, regular use of coxibs for prevention of colorectal adenoma was not supported by the current evidence. Benefit of low-dose Asp for chemoprevention of colorectal adenoma still requires further evidence. PROSPERO, No. CRD42022296376.

Combining gamma-tocopherol and aspirin synergistically suppresses colitis-associated colon tumorigenesis and modulates the gut microbiota in mice, and inhibits the growth of human colon cancer cells

Despite being shown to be effective for chemoprevention of colorectal cancer, aspirin has limitations including adverse effects and inability to block colitis-associated colon cancer (CAC). γ-Tocopherol (γT), a vitamin E form, has been reported to mitigate experimental colitis and CAC, prolong the anti-inflammatory activity of aspirin and alleviate aspirin-induced adverse effect. We therefore hypothesize that combining γT and aspirin is better than either compound singly for suppressing CAC. This hypothesis was tested in the murine azoxymethane (AOM)/dextran sodium sulfate (DSS)-induced CAC model and with human HCT116 colon cancer cells. Compared to the control, combining aspirin (250 ppm) and γT (500 ppm) but not either compound alone significantly reduced AOM/DSS-induced tumor area and multiplicity of large-size tumors by 60% and 50%, respectively. Meanwhile, γT mitigated aspirin-promoted inflammation and stomach lesions in mice. Moreover, the combination appeared to cause favorable changes of gut microbiota compared to the control and synergistically suppressed the growth of HCT116 cells. Our study demonstrates that combining aspirin and γT improves anticancer effects and counteracts side effects compared to aspirin and may therefore be a novel combinatory chemopreventive agent against CAC.