Food‐based approach to cancer prevention

Green Cancer Prevention and Beyond

The concept of green chemoprevention was introduced in 2012 by Drs. Jed Fahey and Thomas Kensler as whole-plant foods and/or extract-based interventions demonstrating cancer prevention activity. Refining concepts and research demonstrating proof-of-principle approaches are highlighted within this review. Early approaches included extensively investigated whole foods, including broccoli sprouts and black raspberries showing dose-responsive effects across a range of activities in both animals and humans with minimal or no apparent toxicity. A recent randomized crossover trial evaluating the detoxification of tobacco carcinogens by a broccoli seed and sprout extract in the high-risk cohort of current smokers highlights the use of a dietary supplement as a potential next-generation green chemoprevention or green cancer prevention approach. Challenges are addressed, including the selection of dose, duration and mode of delivery, choice of control group, and standardization of the plant food or extract. Identification and characterization of molecular targets and careful selection of high-risk cohorts for study are additional important considerations when designing studies. Goals for precision green cancer prevention include acquiring robust evidence from carefully controlled human studies linking plant foods, extracts, and compounds to modulation of targets for cancer risk reduction in individual cancer types.

Adjuvant role of Salvia miltiorrhiza bunge in cancer chemotherapy: A review of its bioactive components, health-promotion effect and mechanisms

ETHNOPHARMACOLOGICAL RELEVANCE

Chemotherapy is a common cancer treatment strategy. However, its effectiveness is constrained by toxicity and adverse effects. The Lamiaceae herb Salvia miltiorrhiza Bunge has a long history of therapeutic use in the treatment of blood stasis illnesses, which are believed by traditional Chinese medicine to be connected to cancer.

AIM OF THE STUDY

This review summarized the common toxicity of chemotherapy and the potential chemo-adjuvant effect and mechanisms of active ingredients from S. miltiorrhiza, hoping to provide valuable information for the development and application of S. miltiorrhiza resources.

MATERIALS AND METHODS

The literatures were retrieved from PubMed, Web of Science, Baidu Scholar and Google Scholar databases from 2002 to 2022. The inclusion criteria were studies reporting that S. miltiorrhiza or its constituents enhanced the efficiency of chemotherapy drugs or reduced the side effects.

RESULTS

Salvianolic acid A, salvianolic acid B, salvianolic acid C, rosmarinic acid, tanshinone I, tanshinone IIA, cryptotanshinone, dihydrotanshinone I and miltirone are the primary adjuvant chemotherapy components of S. miltiorrhiza. The mechanisms mainly involve inhibiting proliferation, metastasis, and angiogenesis, inducing apoptosis, regulating autophagy and tumor microenvironment. In addition, they also improve chemotherapy drug-induced side effects.

CONCLUSIONS

The bioactive compounds of S. miltiorrhiza are shown to inhibit proliferation, metastasis, and angiogenesis, induce apoptosis and autophagy, regulate immunity and tumor microenvironment when combined with chemotherapy drugs. However, further clinical studies are required to validate the current studies.

Asparanin A exerts cytotoxicity on human endometrial cancer Ishikawa cells via regulating miR-6236-p5_4 expression

miRNAs are emerging as a novel proto-oncogene or tumor suppressor in the initiation and progression of cancer. Several plants naturally contain asparanin A (AA), which has potent anticancer properties. Previously, we discovered that AA exposure increased the expression of miR-6236-p5_4 and caused cytotoxicity in endometrial carcinoma (EC) Ishikawa cells. Herein, the regulation mechanism of miR-6236-p5_4 in the anticancer activity of AA in EC was investigated. Our results showed that the overexpressed miR-6236-p5_4 contributed to modulating cell viability and cell cycle arrest, triggering cell apoptosis, and suppressing migration. Conversely, down-regulation of miR-6236-p5_4 attenuated the anti-cancer effect of AA. Additionally, the PI3K-Akt, p53, Ras, and Rap1 signaling pathways were demonstrated to be the key pathways, whereas CDK6, PIK3CB, and KRAS were found to be directly functional target genes. Our findings imply that miRNA-6236-p5_4 can act as both a molecular diagnostic for the clinical identification and prognosis of EC and a tumor suppressor in AA against EC.

Use of Freeze-dried Watercress for Detoxification of Carcinogens and Toxicants in Smokers: Implications of the Findings and Potential Opportunities

Bonorden and colleagues designed a clinical trial to test the hypothesis that daily consumption of freeze-dried watercress, a rich source of the chemopreventive agent phenethyl isothiocyanate, can enhance the detoxification of well-known tobacco and environmental carcinogens and toxicants. Initial results have validated subject compliance and a positive outcome of this study would further support the use of watercress as a whole food-based approach to cancer chemoprevention. On the basis of the design of the clinical trial and the various biological samples to be collected, we discuss potential opportunities to test future hypotheses. See related article, p. 143.

Nobiletin as a chemopreventive natural product against cancer, a comprehensive review

As a leading cause of death, second only to heart disease, cancer has always been one of the burning topics in medical research. When targeting multiple signal pathways in tumorigenesis chemoprevention, using natural or synthetic anti-cancer drugs is a vital strategy to reduce cancer damage. However, toxic effects, multidrug resistance (MDR) as well as cancer stem cells (CSCs) all prominently limited the clinical application of conventional anticancer drugs. With low side effects, strong biological activity, unique mechanism, and wide range of targets, natural products derived from plants are considered significant sources for new drug development. Nobiletin is one of the most attractive compounds, a unique flavonoid primarily isolated from the peel of citrus fruits. Numerous studies in vitro and in vivo have suggested that nobiletin and its derivatives possess the eminent potential to become effective cancer chemoprevention agents through various cellular and molecular levels. This article aims to comprehensively review the anticancer efficacy and specific mechanisms of nobiletin, enhancing our understanding of its chemoprevention properties and providing the latest research findings. At the end of this review, we also give some discussion and future perspectives regarding the challenges and opportunities in nobiletin efficient exploitation.

Developing a Rational, Optimized Product of Centella asiatica for Examination in Clinical Trials: Real World Challenges

Botanical products are frequently sold as dietary supplements and their use by the public is increasing in popularity. However, scientific evaluation of their medicinal benefits presents unique challenges due to their chemical complexity, inherent variability, and the involvement of multiple active components and biological targets. Translation away from preclinical models, and developing an optimized, reproducible botanical product for use in clinical trials, presents particular challenges for phytotherapeutic agents compared to single chemical entities. Common deficiencies noted in clinical trials of botanical products include limited characterization of the product tested, inadequate placebo control, and lack of rationale for the type of product tested, dose used, outcome measures or even the study population. Our group has focused on the botanical Centella asiatica due to its reputation for enhancing cognition in Eastern traditional medicine systems. Our preclinical studies on a Centella asiatica water extract (CAW) and its bioactive components strongly support its potential as a phytotherapeutic agent for cognitive decline in aging and Alzheimer's disease through influences on antioxidant response, mitochondrial activity, and synaptic density. Here we describe our robust, scientific approach toward developing a rational phytotherapeutic product based on Centella asiatica for human investigation, addressing multiple factors to optimize its valid clinical evaluation. Specific aspects covered include approaches to identifying an optimal dose range for clinical assessment, design and composition of a dosage form and matching placebo, sourcing appropriate botanical raw material for product manufacture (including the evaluation of active compounds and contaminants), and up-scaling of laboratory extraction methods to available current Good Manufacturing Practice (cGMP) certified industrial facilities. We also address the process of obtaining regulatory approvals to proceed with clinical trials. Our study highlights the complexity of translational research on botanicals and the importance of identifying active compounds and developing sound analytical and bioanalytical methods for their determination in botanical materials and biological samples. Recent Phase I pharmacokinetic studies of our Centella asiatica product in humans (NCT03929250, NCT03937908) have highlighted additional challenges associated with designing botanical bioavailability studies, including specific dietary considerations that need to be considered.

Anti-fatigue and anti-oxidant effects of curcumin supplementation in exhaustive swimming mice via Nrf2/Keap1 signal pathway

Demands for dietary supplements with anti-fatigue effects are growing fast due to increasing societal demands. Moreover, in highly physically active individuals, there are also significant needs for supplements to improve exercise performance. The present study evaluated the potential anti-fatigue and anti-oxidant effects of curcumin in mice using exhaustive swimming test. Male C57BL/6J mice were randomized into six groups: blank control (Rest), swimming control (Con), Vitamin C (Vc), low-dose curcumin (C₅₀), middle-dose curcumin (C₁₀₀), and high-dose curcumin (C₂₀₀). After a 4-week intervention, the mice in all groups except the Rest group were subject to an exhaustive swimming test. Then, mice were sacrificed to examine serum biochemical markers and fatigue-related enzymes. Moreover, the gene and protein expressions of signal transduction factors involved in the Nrf2/Keap1 signaling pathway were measured. The results indicated that curcumin significantly enhanced the exercise tolerance of mice in the exhaustive swimming test. Particularly, the swimming time of mice in the C₁₀₀ group was increased by 273.5% when compared to that of mice in the Con group. The levels of blood urea nitrogen, blood ammonia, lactic acid, creatine kinase and lactate dehydrogenase in the C₁₀₀ group were decreased by 13.3%, 21.0%, 18.6%, 16.7% and 21.9%, respectively, when compared to those of mice in the Con group. Curcumin alleviated exercise-induced oxidative stress and significantly enhanced the activities of superoxide dismutase, catalase and glutathione peroxidase by activating the Nrf2 signaling. These findings indicated that curcumin supplementation exerted remarkable anti-oxidant and anti-fatigue effects in mice, providing additional evidence supporting the use of curcumin as functional food, especially by those engaged in sports-related activities.

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Curcumin exerted remarkable anti-oxidant and anti-fatigue effects in mice.

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Curcumin can activate anti-oxidant response via Nrf2/Keap1 signaling pathway.

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Curcumin greatly enhanced the exercise tolerance of mice in exhaustive swimming test.

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Curcumin alleviated exercise-induced oxidative stress by its anti-oxidant effects.

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Curcumin can be an anti-fatigue promising candidate improving exercise performance.

Preparation of a Beverage Containing Freeze-Dried Watercress for a Clinical Trial of Carcinogen and Toxicant Detoxification

Watercress is an excellent source of phenethyl isothiocyanate (PEITC), shown in many studies to enhance carcinogen and toxicant detoxification and to inhibit carcinogenesis. Based on a previous observation that PEITC can enhance the detoxification of common environmental pollutants such as acrolein, crotonaldehyde, benzene, and 1,3-butadiene, we designed a clinical trial testing the hypothesis that daily consumption of a drink containing freeze-dried watercress, an abundant source of PEITC, would have a similar effect, particularly observed in subjects who were null in certain glutathione S-transferase genes. This manuscript describes the preparation of nearly 100 pounds of freeze-dried watercress for this trial, starting with laboratory scale pilot studies and proceeding to industrial scale production of the fully validated product in compliance with all food safety requirements. Initial results validating subject compliance in the clinical trial are also presented.

Effect of Limonene on Cancer Development in Rodent Models: A Systematic Review

Cancer is a major health issue and one of the leading causes of death worldwide. Many natural compounds, e.g., lycopene, curcumin, resveratrol, etc., have been shown to inhibit the growth of cancer cells. Similarly, limonene, a major active component in citrus essential oils and widely used flavoring additive, has demonstrated anticarcinogenic effects in both cell and animal studies. This systematic review aimed to evaluate the anticarcinogenic effects of limonene and its potential underlying mechanisms. Eight peer-reviewed articles published in English between 2000 and 2020 were identified after screening using MEDLINE, Academic Search Premier, and CINAHL plus. All 8 studies showed an effect of limonene on reducing tumor burden, resulting in either decreased size, number, weight, or multiplicities of tumors. Limonene treatment extended the latency and survival periods in 2 studies yet did not reduce tumor incidence rate in another study. Limonene was shown to promote cell apoptosis in 4 studies that examined either the apoptosis index or apoptosis related gene/protein expressions. Two studies tried to explain the cancer preventive mechanisms of limonene and found limonene could restore the antioxidant capacity or immune functions that were impaired by cancer. These results supported the potential applicability of limonene on inhibiting cancer development, yet the real-world applicability on human requires more research and evaluation through clinical studies.

Systematic Review Registration: PROSPERO, identifier: CRD42020168387.