Toward a core nutraceutical program for cancer management

Phyto-pharmacological perspective of Silymarin: A potential prophylactic or therapeutic agent for COVID-19, based on its promising immunomodulatory, anti-coagulant and anti-viral property

Coronavirus disease 2019 (COVID‐19) triggered by a new viral pathogen, named severe acute respiratory syndrome Coronavirus‐2 (SARS‐CoV‐2), is now a global health emergency. This debilitating viral pandemic not only paralyzed the normal daily life of the global community but also spread rapidly via global travel. To date there are no effective vaccines or specific treatments against this highly contagious virus; therefore, there is an urgent need to advocate novel prophylactic or therapeutic interventions for COVID‐19. This brief opinion critically discusses the potential of Silymarin, a flavonolignan with diverse pharmacological activity having antiinflammatory, antioxidant, antiplatelet, and antiviral properties, with versatile immune‐cytokine regulatory functions, that able to bind with transmembrane protease serine 2 (TMPRSS2) and induce endogenous antiviral cytokine interferon‐stimulated gene 15, for the management of COVID‐19. Silymarin inhibits the expression of host cell surface receptor TMPRSS2 with a docking binding energy corresponding to −1,350.61 kcal/mol and a full fitness score of −8.11. The binding affinity of silymarin with an impressive virtual score exhibits significant potential to interfere with SARS‐CoV‐2 replication. We propose in‐depth pre‐clinical and clinical review studies of silymarin for the development of anti‐COVID‐19 lead, based on its clinical manifestations of COVID‐19 and multifaceted bioactivities.

Designing a broad-spectrum integrative approach for cancer prevention and treatment

Targeted therapies and the consequent adoption of "personalized" oncology have achieved notable successes in some cancers; however, significant problems remain with this approach. Many targeted therapies are highly toxic, costs are extremely high, and most patients experience relapse after a few disease-free months. Relapses arise from genetic heterogeneity in tumors, which harbor therapy-resistant immortalized cells that have adopted alternate and compensatory pathways (i.e., pathways that are not reliant upon the same mechanisms as those which have been targeted). To address these limitations, an international task force of 180 scientists was assembled to explore the concept of a low-toxicity "broad-spectrum" therapeutic approach that could simultaneously target many key pathways and mechanisms. Using cancer hallmark phenotypes and the tumor microenvironment to account for the various aspects of relevant cancer biology, interdisciplinary teams reviewed each hallmark area and nominated a wide range of high-priority targets (74 in total) that could be modified to improve patient outcomes. For these targets, corresponding low-toxicity therapeutic approaches were then suggested, many of which were phytochemicals. Proposed actions on each target and all of the approaches were further reviewed for known effects on other hallmark areas and the tumor microenvironment. Potential contrary or procarcinogenic effects were found for 3.9% of the relationships between targets and hallmarks, and mixed evidence of complementary and contrary relationships was found for 7.1%. Approximately 67% of the relationships revealed potentially complementary effects, and the remainder had no known relationship. Among the approaches, 1.1% had contrary, 2.8% had mixed and 62.1% had complementary relationships. These results suggest that a broad-spectrum approach should be feasible from a safety standpoint. This novel approach has potential to be relatively inexpensive, it should help us address stages and types of cancer that lack conventional treatment, and it may reduce relapse risks. A proposed agenda for future research is offered.

Chemopreventive Efficacy of Silymarin in Skin and Prostate Cancer

Prevention and therapeutic intervention by phytochemicals are newer dimensions in the arena of cancer management. In this regard, the cancer chemopreventive role of silymarin (Silybum marianum) has been extensively studied and has shown anticancer efficacy against various cancer sites, especially skin and prostate. In skin cancer, silymarin treatment inhibits ultraviolet B radiation or chemically initiated or promoted carcinogenesis. These effects of silymarin against skin carcinogenesis have been attributed to its strong antioxidant and anti-inflammatory action as well as its inhibitory effect on mitogenic signaling. Similarly, silymarin treatment inhibits 3, 2-dimethyl-4-aminobiphenyl—induced prostate carcinogenesis and retards the growth of advanced prostate tumor xenograft in athymic nude mice. In prostate cancer, silymarin treatment down-regulates androgen receptor—, epidermal growth factor receptor—, and nuclear factor-κB— mediated signaling and induces cell cycle arrest. Extensive preclinical findings have supported the anticancer potential of silymarin, and now its efficacy is being evaluated in cancer patients.

Reduced cancer risk in vegetarians: an analysis of recent reports

This report reviews current evidence regarding the relationship between vegetarian eating patterns and cancer risk. Although plant-based diets including vegetarian and vegan diets are generally considered to be cancer protective, very few studies have directly addressed this question. Most large prospective observational studies show that vegetarian diets are at least modestly cancer protective (10%-12% reduction in overall cancer risk) although results for specific cancers are less clear. No long-term randomized clinical trials have been conducted to address this relationship. However, a broad body of evidence links specific plant foods such as fruits and vegetables, plant constituents such as fiber, antioxidants and other phytochemicals, and achieving and maintaining a healthy weight to reduced risk of cancer diagnosis and recurrence. Also, research links the consumption of meat, especially red and processed meats, to increased risk of several types of cancer. Vegetarian and vegan diets increase beneficial plant foods and plant constituents, eliminate the intake of red and processed meat, and aid in achieving and maintaining a healthy weight. The direct and indirect evidence taken together suggests that vegetarian diets are a useful strategy for reducing risk of cancer.

Type IIB procollagen NH(2)-propeptide induces death of tumor cells via interaction with integrins alpha(V)beta(3) and alpha(V)beta(5)

Cartilage is resistant to tumor invasion. In the present study, we found that the NH(2)-propeptide of the cartilage-characteristic collagen, type IIB, PIIBNP, is capable of killing tumor cells. The NH(2)-propeptide is liberated into the extracellular matrix prior to deposition of the collagen fibrils. This peptide adheres to and kills cells from chondrosarcoma and cervical and breast cancer cell lines via the integrins alpha(v)beta(5) and alpha(v)beta(3). Adhesion is abrogated by blocking with anti alpha(v)beta(5) and alpha(v)beta(3) antibodies. When alpha(v) is suppressed by small intefering RNA, adhesion and cell killing are blocked. Normal chondrocytes from developing cartilage do not express alpha(v)beta(3) and alpha(v)beta(5) integrins and are thus protected from cell death. Morphological, DNA, and biochemical evidence indicates that the cell death is not by apoptosis but probably by necrosis. In an assay for invasion, PIIBNP reduced the number of cells crossing the membrane. In vivo, in a tumor model for breast cancer, PIIBNP was consistently able to reduce the size of the tumor.

Modified citrus pectin anti-metastatic properties: one bullet, multiple targets

In this minireview, we examine the ability of modified citrus pectin (MCP), a complex water soluble indigestible polysaccharide obtained from the peel and pulp of citrus fruits and modified by means of high pH and temperature treatment, to affect numerous rate-limiting steps in cancer metastasis. The anti-adhesive properties of MCP as well as its potential for increasing apoptotic responses of tumor cells to chemotherapy by inhibiting galectin-3 anti-apoptotic function are discussed in the light of a potential use of this carbohydrate-based substance in the treatment of multiple human malignancies.

Influence of diet on metastasis and tumor dormancy

Tumor metastasis is responsible for most cancer deaths, and can occur after long periods of tumor dormancy. Information learned from experimental studies on tumor metastasis and dormancy is shedding light on mechanisms responsible and possible therapeutic approaches. 'Seed' (the cancer cell) and 'soil' (the microenvironment of the secondary organ) factors contribute to metastatic outcome. This review considers the possibility that various dietary components may affect both 'seed' and 'soil' compartments, thereby influencing the growth of metastases, and discusses an experimental study on dietary genistein that illustrates this concept. While studies on human diet are complex, the possibility that relatively non-toxic dietary intervention strategies could impact on metastasis and patient survival is attractive and worthy of further study in appropriate experimental models of metastasis and tumor dormancy.

Pectin does not inhibit intestinal carcinogenesis in APC-deficient Min/+ mice

APC-germline mutation creates predisposition for intestinal tumorigenesis. APCMin/+ mice, developing tumors preferentially in the small intestine and only minimally in the colon, were fed pectin-enriched diets (10% galacturonan; degree of methoxylation=37.0 and 70.4%) or standard diet. Pectins used in the present study do not inhibit intestinal tumorigenesis and rather accelerate it in APCMin/+ mice. Both pectins exhibited prebiotic effects associated with high fermentative formation of acetate but producing low butyrate. The differences of the short-chain fatty acid concentrations between cecum and colon and those between colon and feces were larger than expected and increased with cancer progression, indicating an inhibition of butyrate absorption. Pectins transported more bile acids toward the colon than the standard diet and caused a higher generation of secondary bile acids despite lower pH values. Overexpression of COX-2 resulted in lower antioxidative capacity, thus promoting cancer. Apoptosis increased in hyperplasia but decreased in late adenomas. When biological modular design principles are taken into consideration, it can be expected that pectin also reinforces colorectal tumorigenesis of patients suffering from APC gene defects.

Modulation of response to cancer chemotherapeutic agents by diet constituents – Is the available evidence sufficiently robust for rational advice for patients?

BACKGROUND

Patients who are diagnosed with cancer want advice on how they may alter their diet or which diet supplements they should take to augment chemotherapy.

METHODS

We conducted a review of the literature mostly from the last 15 years on the interaction between dietary constituents and antineoplastic therapy in preclinical rodent models and in clinical trials.

RESULTS

Studies have explored the effect of predominantly antioxidant vitamins and folate on efficacy or toxicity mediated by cisplatin and anthracyclins. Cisplatin toxicity in rodents was ameliorated by vitamin E. The design of clinical studies of dietary agents in combination with cytotoxic agents has been very heterogeneous and results have been inconclusive.

CONCLUSIONS

Whilst preclinical experiments hint at a potential benefit of certain dietary agents, the evidence emanating from clinical studies does not allow firm conclusions to be made. Future studies should explore physiological doses of dietary agent and include pharmacokinetic and pharmacodynamic measurements.

Effects of silymarin on the spontaneous proliferation and cell cycle of human peripheral blood leukemia T cells

Silymarin is a polyphenolic flavonoid that has a strong antioxidant activity and exhibits anti-carcinogenic, anti-inflammatory, and cytoprotective effects. Although its hepatoprotective effect has been well documented, the effect of silymarin on T cells is largely unknown. The purpose of this study was to analyze the effects of the silymarin on the proliferation and cell cycle progression of Jurkat cells, a human peripheral blood leukemia T cell line. Cells were incubated with various concentrations of silymarin for 24-72 h and examined for cell growth and proliferation using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) and DNA 5-bromo 2'-deoxyuridine (BrdU) colorimetric assays. Cell cycle analysis by flow cytometry was also performed using propidium iodide staining. Results of the study revealed that silymarin increased proliferation of Jurkat cells at 50-400 microM concentrations with 24 h exposure, confirmed by both MTT and BrdU assays. However, Jurkat incubation with silymarin at higher concentrations of 400 microM for 48 h and 200-400 microM for 72 h caused inhibition of DNA synthesis, cell cycle arrest at the G2/M phase and significant cell death. Results of the present study also revealed a similarity of cell growth patterns between Jurkat, U937 and RPMI 8866 cells. In conclusion, this study demonstrated an in vitro growth stimulatory effect of silymarin on leukemia cells with monocyte, T and B cell origin that has not been previously reported for either solid tumors or other leukemia cells, suggesting a possible specific stimulatory effect of silymarin on the key cells of the immune system.