Gallotannin-rich Caesalpinia spinosa fraction decreases the primary tumor and factors associated with poor prognosis in a murine breast cancer model

Triple negative breast cancer migration is modified by mitochondrial metabolism alteration induced by natural extracts of C. spinosa and P. alliacea

Tumor metabolism is a crucial aspect of cancer development, and mitochondria plays a significant role in the aggressiveness and metastasis of tumors. As a result, mitochondria have become a promising therapeutic target in cancer treatment, leading to the development of compounds known as mitocans. In our group, we have consolidated the search of anticancer therapies based on natural products derived from plants, obtaining extracts such as P2Et from Caesalpinia spinosa and Anamu-SC from Petiveria alliacea, which have been shown to have antitumor activities in different cancer models. These extracts, due to their complex molecular composition, can interfere with multiple functions during tumor progression. To better understand how these natural products operate (P2Et and Anamu-SC), we constructed a model using 4T1 murine breast cancer cells with reduced expression of genes associated with glycolysis (Hexokinase-2) and mitochondrial function (Cqbp). The results indicate that the cells were more sensitive to the Anamu-SC extract, showing significant decreases in glucose consumption, ATP production, and oxygen consumption rate. Additionally, we observed changes in mitochondrial function, which reduced the cells' ability to migrate, particularly when C1qbp was silenced. This triple-negative breast cancer model allows us to identify potential natural products that can modulate tumor cell metabolism.

The secretome from human-derived mesenchymal stem cells augments the activity of antitumor plant extracts in vitro

Cancer is understood as a multifactorial disease that involve multiple cell types and phenotypes in the tumor microenvironment (TME). The components of the TME can interact directly or via soluble factors (cytokines, chemokines, growth factors, extracellular vesicles, etc.). Among the cells composing the TME, mesenchymal stem cells (MSCs) appear as a population with debated properties since it has been seen that they can both promote or attenuate tumor progression. For various authors, the main mechanism of interaction of MSCs is through their secretome, the set of molecules secreted into the extracellular milieu, recruiting, and influencing the behavior of other cells in inflammatory environments where they normally reside, such as wounds and tumors. Natural products have been studied as possible cancer treatments, appealing to synergisms between the molecules in their composition; thus, extracts obtained from Petiveria alliacea (Anamu-SC) and Caesalpinia spinosa (P2Et) have been produced and studied previously on different models, showing promising results. The effect of plant extracts on the MSC secretome has been poorly studied, especially in the context of the TME. Here, we studied the effect of Anamu-SC and P2Et extracts in the human adipose-derived MSC (hAMSC)-tumor cell interaction as a TME model. We also investigated the influence of the hAMSC secretome, in combination with these natural products, on tumor cell hallmarks such as viability, clonogenicity, and migration. In addition, hAMSC gene expression and protein synthesis were evaluated for some key factors in tumor progression in the presence of the extracts by reverse transcription-quantitative polymerase chain reaction (RT-qPCR) and Multiplex, respectively. It was found that the presence of the hAMSC secretome did not affect the cytotoxic or clonogenicity-reducing activities of the natural extracts on cancer cells, and even this secretome can inhibit the migration of these tumor cells, in addition to the fact that the profile of molecules can be modified by natural products. Overall, our findings demonstrate that hAMSC secretome participation in TME interactions can favor the antitumor activities of natural products.

Assessment of Acute and Chronic Toxicity in Wistar Rats (Rattus norvegicus) and New Zealand Rabbits (Oryctolagus cuniculus) of an Enriched Polyphenol Extract Obtained from Caesalpinia spinosa

Although herbal drugs are often considered safe for consumption, there is increasing evidence that some can generate undesirable health effects. However, polyphenols found in certain plants have been shown to provide a range of benefits for human health. In previous work, a standardized and quantified extract (P2Et) obtained from Caesalpinia spinosa (Dividivi) plant showed promising antioxidant, immunomodulatory, and anti-inflammatory properties in animal models of cancer and COVID-19 patients. The extract has also been subjected to genotoxicity, mutagenicity, and 28-day oral chronic toxicity evaluations, demonstrating a good safety profile. To advance preclinical and clinical development, further acute and chronic toxicity evaluations of the P2Et extract were performed. Acute toxicity tests were performed orally in Wistar rats at a dose of 2000 mg/kg, indicating that the lethal dose 50% (LD50) value exceeded 2000 mg/kg and classifying the P2Et extract as category 5 according to the Globally Harmonized System of Classification (GHS). In this work, chronic toxicity tests were conducted for 180 days on Wistar rats and New Zealand rabbits at a dose of 1000 mg/kg under Good Laboratory Practice (GLP) conditions. No weight loss or alterations in biochemical and hematological parameters associated with treatment were observed in the animals, suggesting the absence of toxicity in the assessed parameters. These results indicate that the P2Et extract is safe for oral administration at doses up to 1000 mg/kg body weight over a six-month period.

Effect of Petiveria alliacea Extracts on Metabolism of K562 Myeloid Leukemia Cells

Previously, studies have shown that leukemic cells exhibit elevated glycolytic metabolism and oxidative phosphorylation in comparison to hematopoietic stem cells. These metabolic processes play a crucial role in the growth and survival of leukemic cells. Due to the metabolic plasticity of tumor cells, the use of natural products has been proposed as a therapeutic alternative due to their ability to attack several targets in tumor cells, including those that could modulate metabolism. In this study, the potential of Petiveria alliacea to modulate the metabolism of K562 cell lysates was evaluated by non-targeted metabolomics. Initially, in vitro findings showed that P. alliacea reduces K562 cell proliferation; subsequently, alterations were observed in the endometabolome of cell lysates treated with the extract, mainly in glycolytic, phosphorylative, lipid, and amino acid metabolism. Finally, in vitro assays were performed, confirming that P. Alliacea extract decreased the oxygen consumption rate and intracellular ATP. These results suggest that the anti-tumor activity of the aqueous extract on the K562 cell line is attributed to the decrease in metabolites related to cell proliferation and/or growth, such as nucleotides and nucleosides, leading to cell cycle arrest. Our results provide a preliminary part of the mechanism for the anti-tumor and antiproliferative effects of P. alliacea on cancer.

Piper nigrum extract suppresses tumor growth and enhances the antitumor immune response in murine models of breast cancer and melanoma

Although the antitumor effect of P. nigrum has been widely studied, research related to its possible immunomodulatory effects is relatively scarce. Here, the antitumor and immunomodulatory activity of an ethanolic extract of P. nigrum were evaluated in the murine models of 4T1 breast cancer and B16-F10 melanoma. In vitro evaluations showed that the P. nigrum extract has cytotoxic activity, induces apoptotic cell death, and has a pro-oxidant effect in both cell lines, but it regulates glucose uptake differently in both lines, decreasing it in 4T1 but not in B16-F10. P. nigrum extract significantly reduced tumor size in both models and decreased the occurrence of macrometastases in 4T1 model. Evaluation of immune subpopulations by flow cytometry revealed that the P. nigrum extract significantly increases the frequency of dendritic cells and activated CD8+ T cells and decreases the frequency of myeloid-derived suppressor like cells and Tregs in the tumor microenvironment of both models but with different dynamics. Our findings strongly suggest that the P. nigrum extract exerts immunomodulatory functions, slightly related to the modulation of cellular energy metabolism, which could ultimately contribute to the promising antitumor effect of P. nigrum.

Safety and efficacy of P2Et extract from Caesalpinia spinosa in breast cancer patients: study protocol for a randomized double blind phase II clinical trial (CS003-BC)

BACKGROUND

Chemotherapy in breast cancer is effective but can generate significant toxicity and lead to tumor resistance. Joint treatment with standardized plant extracts can be an alternative to improve the response and allow an effective activation of the antitumor immune response that favors recovery in the short and long term. The P2Et extract of Caesalpinia spinosa presents antitumor activity in cells and animal models of breast cancer, improves the tumor microenvironment, and induces activation of the specific immune response against the tumor and is synergistic when used together with anthracyclines, which makes it a good candidate for evaluation in patients.

METHODS

Conducted at a single center, this phase II study is a randomized, double-blind, placebo-controlled trial aimed at assessing the safety and efficacy of P2Et extract in patients diagnosed with stage II and III breast cancer, who are eligible for neoadjuvant treatment. The study aims to determine the safety profile at the previously established optimal biological dose from phase I trial while investigating various efficacy outcomes. These outcomes include improvements in quality of life, immunomodulation, metabolic profile, microbiome, as well as clinical indicators such as tumor reduction, disease-free survival, and pathological response, assessed at different stages of the treatment regimen.

DISCUSSION

Treatment with the P2Et extract in breast cancer patients is hypothesized to enhance overall well-being, positively influencing their quality of life, while also triggering an antitumor immune response and enhancing immune infiltration. These combined effects have the potential to contribute to improved long-term survival outcomes for patients receiving the phytomedicine alongside neoadjuvant chemotherapy treatment.

TRIAL REGISTRATION

This trial was registered in the US National Library of Medicine with identifier NCT05007444. First Registered August 16th, 2021. Last Updated: August 9th, 2022.

Plant-derived extracts and metabolic modulation in leukemia: a promising approach to overcome treatment resistance

Leukemic cells acquire complex and often multifactorial mechanisms of resistance to treatment, including various metabolic alterations. Although the use of metabolic modulators has been proposed for several decades, their use in clinical practice has not been established. Natural products, the so-called botanical drugs, are capable of regulating tumor metabolism, particularly in hematopoietic tumors, which could partly explain the biological activity attributed to them for a long time. This review addresses the most recent findings relating to metabolic reprogramming-Mainly in the glycolytic pathway and mitochondrial activity-Of leukemic cells and its role in the generation of resistance to conventional treatments, the modulation of the tumor microenvironment, and the evasion of immune response. In turn, it describes how the modulation of metabolism by plant-derived extracts can counteract resistance to chemotherapy in this tumor model and contribute to the activation of the antitumor immune system.

Modulation of Myeloid-Derived Suppressor Cells in the Tumor Microenvironment by Natural Products

During carcinogenesis, the microenvironment plays a fundamental role in tumor progression and resistance. This tumor microenvironment (TME) is characterized by being highly immunosuppressive in most cases, which makes it an important target for the development of new therapies. One of the most important groups of cells that orchestrate immunosuppression in TME is myeloid-derived suppressor cells (MDSCs), which have multiple mechanisms to suppress the immune response mediated by T lymphocytes and thus protect the tumor. In this review, we will discuss the importance of modulating MDSCs as a therapeutic target and how the use of natural products, due to their multiple mechanisms of action, can be a key alternative for modulating these cells and thus improve response to therapy in cancer patients.

Doxorubicin Activity Is Modulated by Traditional Herbal Extracts in a 2D and 3D Multicellular Sphere Model of Leukemia

The modulation of the tumor microenvironment by natural products may play a significant role in the response of tumor cells to chemotherapy. In this study, we evaluated the effect of extracts derived from P2Et (Caesalpinia spinosa) and Anamú-SC (Petiveria alliacea) plants, previously studied by our group, on the viability and ROS levels in the K562 cell line (Pgp- and Pgp+), endothelial cells (ECs, Eahy.926 cell line) and mesenchymal stem cells (MSC) cultured in 2D and 3D. The results show that: (a) the two botanical extracts are selective on tumor cells compared to doxorubicin (DX), (b) cytotoxicity is independent of the modulation of intracellular ROS for plant extracts, unlike DX, (c) the interaction with DX can be influenced by chemical complexity and the expression of Pgp, (d) the 3D culture shows a greater sensitivity of the tumor cells to chemotherapy, in co-treatment with the extracts. In conclusion, the effect of the extracts on the viability of leukemia cells was modified in multicellular spheroids with MSC and EC, suggesting that the in vitro evaluation of these interactions can contribute to the comprehension of the pharmacodynamics of the botanical drugs.

Encapsulated Phytomedicines against Cancer: Overcoming the "Valley of Death"

P2Et is the standardized extract of Caesalpinia spinosa (C. spinosa), which has shown the ability to reduce primary tumors and metastasis in animal models of cancer, by mechanisms involving the increase in intracellular Ca++, reticulum stress, induction of autophagy, and subsequent activation of the immune system. Although P2Et has been shown to be safe in healthy individuals, the biological activity and bioavailability can be increased by improving the dosage form. This study investigates the potential of a casein nanoparticle for oral administration of P2Et and its impact on treatment efficacy in a mouse model of breast cancer with orthotopically transplanted 4T1 cells. Animals were treated with either free or encapsulated oral P2Et orally or i.p. Tumor growth and macrometastases were evaluated. All P2Et treatments significantly delayed tumor growth. The frequency of macrometastasis was reduced by 1.1 times with P2Et i.p., while oral P2Et reduced it by 3.2 times and nanoencapsulation reduced it by 3.57 times. This suggests that nanoencapsulation led to higher doses of effective P2Et being delivered, slightly improving bioavailability and biological activity. Therefore, the results of this study provide evidence to consider P2Et as a potential adjuvant in the treatment of cancer, while the nanoencapsulation of P2Et provides a novel perspective on the delivery of these functional ingredients.

Plant extract from Caesalpinia spinosa inhibits cancer-associated fibroblast-like cells generation and function in a tumor microenvironment model

Interactions in the tumor microenvironment (TME) between tumor cells and stromal cells such as cancer-associated fibroblasts (CAF) favor increased survival, progression, and transformation of cancer cells by activating mechanisms of invasion and metastasis. The design of new therapies to modulate or eliminate the CAF phenotype or functionality has been the subject of recent research including natural product-based therapies. We have previously described the generation of a standardized extract rich in polyphenols obtained from the Caesalpinia spinosa plant (P2Et), which present antitumor activities in breast cancer and melanoma models through activities that modulate the metabolism of tumor cells or induce the development of the immune response. In this work, a model of CAF generation was initially developed from the exposure of 3T3 fibroblasts to the cytokine TGFβ1. CAF-like cells generated in this way exhibited changes in the expression of Caveolin-1 and α-SMA, and alterations in glucose metabolism and redox status, typical of CAFs isolated from tumor tissues. Then, P2Et was shown to counteract in vitro-induced CAF-like cell generation, preventing caveolin-1 loss and attenuating changes in glucose uptake and redox profile. This protective effect of P2Et translates into a decrease in the functional ability of CAFs to support colony formation and migration of 4T1 murine breast cancer tumor cells. In addition to the functional interference, the P2Et extract also decreased the expression of genes associated with the epithelial-mesenchymal transition (EMT) and functional activities related to the modulation of the cancer stem cells (CSC) population. This work is an in vitro approach to evaluate natural extracts' effect on the interaction between CAF and tumor cells in the tumor microenvironment; thus, these results open the chance to design a more profound and mechanistic analysis to explore the molecular mechanisms of P2Et multimolecular activity and extent this analysis to an in vivo perspective. In summary, we present here a standardized polymolecular natural extract that has the potential to act in the TME by interfering with CAF generation and functionality.

Tillandsia usneoides Extract Decreases the Primary Tumor in a Murine Breast Cancer Model but Not in Melanoma

The main limits of current antitumor therapies are chemoresistance, relapses, and toxicity that impair patient quality of life. Therefore, the discovery of therapeutic alternatives, such as adjuvants to conventional therapy that modulate the intracellular oxidation state or the immune response, remains a challenge. Owing to traditional medicine, several uses of plants are known, indicating a promising antitumor and immunomodulatory effect. We evaluated the effect of ethanolic extract of T. usneoides in vitro and in vivo in models of 4T1 breast cancer and B16-F10 melanoma. In vitro evaluations with both cell lines showed that the extract has cytotoxic activity and induces apoptotic cell death. However, its effect on ROS production and glucose uptake was opposite. In vivo, only in the 4T1 model, a significant decrease in tumor size was found in animals treated with the extract, accompanied by an increase in dendritic cells and activated CD8⁺ T cells, and a decrease in myeloid-derived suppressor-like cells (MDSC-LC) and Tregs in the tumor microenvironment. These results suggest that T. usneoides extract antagonistically regulates tumor metabolism of 4T1 vs. B16-F10, impacting the tumor microenvironment and effective antitumor immune response, leading to a reduction in 4T1 tumor size but not on B16-F10.

Randomized double-blind clinical study in patients with COVID-19 to evaluate the safety and efficacy of a phytomedicine (P2Et)

Background

It has been proposed that polyphenols can be used in the development of new therapies against COVID-19, given their ability to interfere with the adsorption and entrance processes of the virus, thus disrupting viral replication. Seeds from Caesalpinia spinosa, have been traditionally used for the treatment of inflammatory pathologies and respiratory diseases. Our team has obtained an extract called P2Et, rich in polyphenols derived from gallic acid with significant antioxidant activity, and the ability to induce complete autophagy in tumor cells and reduce the systemic inflammatory response in animal models.

Methods

In this work, a phase II multicenter randomized double-blind clinical trial on COVID-19 patients was designed to evaluate the impact of the P2Et treatment on the clinical outcome and the immunological parameters related to the evolution of the disease. The Trial was registered with the number No. NCT04410510^*. A complementary study in an animal model of lung fibrosis was carried out to evaluate in situ lung changes after P2Et in vivo administration. The ability of P2Et to inhibit the viral load of murine and human coronaviruses in cellular models was also evaluated.

Results

Patients treated with P2Et were discharged on average after 7.4 days of admission vs. 9.6 days in the placebo group. Although a decrease in proinflammatory cytokines such as G-CSF, IL-15, IL-12, IL-6, IP10, MCP-1, MCP-2 and IL-18 was observed in both groups, P2Et decreased to a greater extent G-CSF, IL-6 and IL-18 among others, which are related to lower recovery of patients in the long term. The frequency of T lymphocytes (LT) CD3+, LT double negative (CD3+CD4-CD8-), NK cells increased in the P2Et group where the population of eosinophils was also significantly reduced. In the murine bleomycin model, P2Et also reduced lung inflammation and fibrosis. P2Et was able to reduce the viral replication of murine and human coronaviruses in vitro, showing its dual antiviral and anti-inflammatory role, key in disease control.

Conclusions

Taken together these results suggest that P2Et could be consider as a good co-adjuvant in the treatment of COVID-19.

Clinical trail registration

https://clinicaltrials.gov/ct2/show/NCT04410510, identifier: NCT04410510.

Safety Evaluation in Healthy Colombian Volunteers of P2Et Extract Obtained from Caesalpinia spinosa: Design 3+3 Phase I Clinical Trial

The polyphenol-enriched extract called P2Et derived from Caesalpinia spinosa (C. spinosa) had antitumor and immunomodulatory activities reported in breast cancer, leukemia, and melanoma. The aim of this study was to evaluate the safety and maximum tolerated dose of P2Et extract in Colombian healthy volunteers in a phase 1 clinical trial, open labelled, single-arm, dose-escalation design 3 + 3. Seven healthy volunteers were included; P2Et was administrated in capsules of 600 mg/d for 28 days. Analysis by intention to treat was performed. 4 volunteers showed adverse events and discontinued the intervention. 94.6% of AE were grade 1, and most of AE had a reasonable possibility of a relationship with the P2Et (83.8%). We found that the oral administration of P2Et is safe in healthy humans with a maximum tolerated dose of 600 mg/d. There was no severe toxicity; most of the adverse events were mild, without significant changes in the safety parameters evaluated.

Current Advancements of Plant-Derived Agents for Triple-Negative Breast Cancer Therapy through Deregulating Cancer Cell Functions and Reprogramming Tumor Microenvironment

Triple-negative breast cancer (TNBC) is defined based on the absence of estrogen, progesterone, and human epidermal growth factor receptor 2 receptors. Currently, chemotherapy is the major therapeutic approach for TNBC patients; however, poor prognosis after a standard chemotherapy regimen is still commonplace due to drug resistance. Abnormal tumor metabolism and infiltrated immune or stromal cells in the tumor microenvironment (TME) may orchestrate mammary tumor growth and metastasis or give rise to new subsets of cancer cells resistant to drug treatment. The immunosuppressive mechanisms established in the TME make cancer cell clones invulnerable to immune recognition and killing, and turn immune cells into tumor-supporting cells, hence allowing cancer growth and dissemination. Phytochemicals with the potential to change the tumor metabolism or reprogram the TME may provide opportunities to suppress cancer metastasis and/or overcome chemoresistance. Furthermore, phytochemical intervention that reprograms the TME away from favoring immunoevasion and instead towards immunosurveillance may prevent TNBC metastasis and help improve the efficacy of combination therapies as phyto-adjuvants to combat drug-resistant TNBC. In this review, we summarize current findings on selected bioactive plant-derived natural products in preclinical mouse models and/or clinical trials with focus on their immunomodulatory mechanisms in the TME and their roles in regulating tumor metabolism for TNBC prevention or therapy.

Effects of Onosma dichroanthum Boiss. root extract on AGS human gastric cancer cell-line

One of the cancer-related deaths is gastric cancer in this area. Onosma dichroanthum Boiss. roots have been used as an antiseptic and anti-inflammatory for wound healing treatment. The aim of this study was to assess the in vitro cytotoxic and anticancer effects of O. dichroanthum Boiss. roots from the Golestan province of Iran. After identification of the taxonomical effect of O. dichroanthum Boiss., different concentrations of the hydroalcoholic root extract were used. Three different time periods (24, 48, and 72 h) were used to treat AGS gastric cancer and L-929 normal fibroblasts cell lines. The evaluation of different concentrations of root extract was performed by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. The 48 h treatment affected cell survival, while the concentration of 64 μg/mL was determined as IC₅₀ concentrations at 48 h incubation time. The 48 h incubation time with 64 μg/mL showed the best effectiveness on cancerous cell-line while being safe for normal cell-line. Our results show that O. dichroanthum Boiss. roots extract may have cytotoxic and safe effects on gastric cancer cell-line and normal cells in 48 h treatment periods, respectively. The results indicated the O. dichroanthum Boiss. may be as an effective anticancer agent (gastric cancer).

Effects of Gallotannin-Enriched Extract of Galla Rhois on the Activation of Apoptosis, Cell Cycle Arrest, and Inhibition of Migration Ability in LLC1 Cells and LLC1 Tumors

Gallotannin (GT) and GT-enriched extracts derived from various sources are reported to have anti-tumor activity in esophageal, colon and prostate tumors, although their anti-tumor effects have not been determined in lung carcinomas. To investigate the anti-tumor activity of GT-enriched extract of galla rhois (GEGR) against lung carcinomas, alterations in the cytotoxicity, apoptosis activation, cell cycle progression, migration ability, tumor growth, histopathological structure, and the regulation of signaling pathways were analyzed in Lewis lung carcinoma (LLC1) cells and LLC1 tumor bearing C57BL/6NKorl mice, after exposure to GEGR. A high concentration of GT (69%) and DPPH scavenging activity (IC50=7.922 µg/ml) was obtained in GEGR. GEGR treatment exerted strong cytotoxicity, cell cycle arrest at the G2/M phase and subsequent activation of apoptosis, as well as inhibitory effects on the MAPK pathway and PI3K/AKT mediated cell migration in LLC1 cells. In the in vivo syngeneic model, exposure to GEGR resulted in suppressed growth of the LLC1 tumors, as well as inhibition of NF-κB signaling and their inflammatory cytokines. Taken together, our results provide novel evidence that exposure to GEGR induces activation of apoptosis, cell cycle arrest, and inhibition of cell migration via suppression of the MAPK, NF-κB and PI3K/AKT signaling pathways in LLC1 cells and the LLC1 syngeneic model.

Genotoxicity and mutagenicity assessment of a standardized extract (P2Et) obtained from Caesalpinia spinosa

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The P2Et extract was assessed for genotoxicity and mutagenicity activity.

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The P2Et extract showed no genotoxicity in Micronucleus assay.

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The P2Et extract showed no mutagenicity in Ames test.

The standardized P2Et extract obtained from Caesalpinia spinosa has shown antioxidant, and direct antitumor activity, but also activation of specific immune response through the induction of tumor immunogenic cell death in breast and melanoma cancer models. The present work evaluated the mutagenicity and genotoxicity profile of P2Et to continue the development of the P2Et. Genotoxicity was evaluated by OECD 1997 a guideline and mutagenicity by OECD 2016. At P2Et’s doses of 500, 1000, and 2000 mg/kg body weight in mice (Mus musculus), the difference between the number of micronuclei in PCE of the groups were not statistically significant (17 (negative control), 15 (500 mg/kg), 15 (1000 mg/kg), 19 (2000 mg/kg) and 271 (positive control). Similarly, P2Et did not induce gene mutations by base pair changes or frameshifts in the genome of Salmonella Typhimurium strains TA98, TA100, TA102, TA1535 and TA1537 at the tested range of concentrations up to 5000 μg/plate in the absence and presence of metabolic activation. Therefore, the P2Et was considered as non- mutagenic and non-genotoxic at the conditions of the tests.

Preliminary chemical characterization of ethanolic extracts from Colombian plants with promising anti - Trypanosoma cruzi activity

Chagas disease is caused by Trypanosoma cruzi, and it is an important cause of morbidity and mortality in Latin America. There are no vaccines, and the chemotherapy available to treat this infection has serious side effects. In a search for alternative treatments, we determined the in vitro susceptibility of epimastigote and trypomastigote forms of T. cruzi and the cytotoxic effects on peripheral blood mononuclear cells (PBMCs) of ethanolic extracts obtained from six different plant species. The ethanolic extracts of Ageratina vacciniaefolia, Clethra fimbriata and Siparuna sessiliflora showed antiprotozoal activity against epimastigotes and low cytotoxicity in mammalian cells. However, only the ethanolic extract of C. fimbriata showed activity against T. cruzi trypomastigotes, and it had low cytotoxicity in PBMCs. An analysis on the phytochemical composition of C. fimbriata extract showed that its metabolites were primarily represented by two families of compounds: flavonoids and terpenoids. Lastly, we analyzed whether the A. vacciniaefolia, C. fimbriata, or S. sessiliflora ethanolic extracts induced IFN-γ or TNF-α production. Significantly, ethanolic extracts of C. fimbriata induced TNF-α production and S. sessiliflora induced both cytokines. In addition, C. fimbriata and S. sessiliflora induced the simultaneous secretion of IFN-γ and TNF-α in CD8⁺ T cells. The antiprotozoal and immunomodulatory activity of C. fimbriata may be related to the presence of flavonoid and triterpene compounds in the extract. Thus, these findings suggest that C. fimbriata may represent a valuable source of new bioactive compounds for the therapeutic treatment of Chagas disease that combines trypanocidal activity with the capacity to boost the immune response.

Preferential Activity of Petiveria alliacea Extract on Primary Myeloid Leukemic Blast

The need for new therapeutic approaches to improve the response in acute leukemia (AL), either by directing therapy or with new therapeutic alternatives, has been a research and clinical interest topic. We evaluated whether blasts from AL patients were sensitive ex vivo to the induction chemotherapy and whether the extracts of Petiveria alliacea (Anamu SC) and Caesalpinia spinosa (P2Et) modulated the sensitivity of leukemic cells to death. Bone marrow samples were taken from 26 patients with de novo AL and 6 in relapse, and the cytotoxicity of the extracts alone or in combination with the chemotherapeutic was evaluated by XTT. Patients were classified as good (GR) and bad responders (BR) according to the ex vivo test. 70.5% of the GR patients to the ex vivo test achieved postinduction remission to induction chemotherapy with a median overall survival of 12.50 months versus 7.23 months in the two groups. Furthermore, it was found that the ex vivo response to extracts and chemotherapeutics is heterogeneous and shows an exclusive pattern between the extracts, Anamu being the more effective in inducing cell death. The combination of extracts with chemotherapeutic agents showed synergistic or antagonistic effects in the patients' blasts. These results show that the ex vivo evaluation of the sensitivity to induction drugs using primary blasts from patients exhibits a correlation with the response to induction chemotherapy in patients. These analyses would allow establishing a system to predict response to treatment and determine ex vivo susceptibility to new therapies under development, among which is phytotherapeutics.

Phytochemical and antioxidant characterization, cytogenotoxicity and antigenotoxicity of the fractions of the ethanolic extract of in Poincianella bracteosa (Tul.) L.P. Queiroz

has been widely used in folk medicine to treat catarrhal infections, diarrhea, and anemia; however, phytochemical and toxicogenetic data are still lacking. The objective of this study was to examine the phytochemical and antioxidant characteristics as well as assess cytogenotoxicity and antigenotoxicity in hexane (HF), ether (EF) and ethyl acetate (AF) fractions of P. bracteosa leaves using Allium cepa bioassay. Phytochemical analysis revealed the presence of saponins and phenolic groups. EF fraction contained a higher content of total phenolics (441.23 ± 1.82 mg GAE/g), while HF fraction showed a higher content of total flavonoids (84.77 ± 5.33 mg QE/g). Higher antioxidant activity was observed in EF (EC₅₀ 25.06 ± 0.07 µg/ml). Cytotoxic effect was verified for all fractions, but no chromosomal alterations were observed in the A. cepa assay. With respect to antigenotoxicity, the protective effect of EF and AF fractions was attributed to as evidenced by the modulation of mutagenic action of methyl methanesulfonate (MMS), mainly by inhibiting the development of micronuclei. Among the fractions, EF was considered the most promising, as it exhibited higher antioxidant activity, was not genotoxic, exerted protective activity against the damage induced by MMS and also presented cytotoxic activity, a desired quality in the search for natural anticarcinogenic compounds.

An Immunomodulatory Gallotanin-Rich Fraction From Caesalpinia spinosa Enhances the Therapeutic Effect of Anti-PD-L1 in Melanoma

PD-1/PD-L1 pathway plays a role in inhibiting immune response. Therapeutic antibodies aimed at blocking the PD-1/PD-L1 interaction have entered clinical development and have been approved for a variety of cancers. However, the clinical benefits are reduced to a group of patients. The research in combined therapies, which allow for a greater response, is strongly encouraging. We previously characterized a polyphenol-rich extract from Caesalpinia spinosa (P2Et) with antitumor activity in both melanoma and breast carcinoma, as well as immunomodulatory activity. We hypothesize that the combined treatment with P2Et and anti-PD-L1 can improve the antitumor response through an additive antitumor effect. We investigated the antitumor and immunomodulatory activity of P2Et and anti-PD-L1 combined therapy in B16-F10 melanoma and 4T1 breast carcinoma. We analyzed tumor growth, hematologic parameters, T cell counts, cytokine expression, and T cell cytotoxicity. In the melanoma model, combined P2Et and anti-PD-L1 therapy has the following effects: decrease in tumor size; increase in the number of activated CD4⁺ and CD8⁺ T cells; decrease in the number of suppressor myeloid cells; increase in PD-L1 expression; decrease in the frequency of CD8⁺ T cell expressing PD-1; improvement in the cytotoxic activity of T cells; and increase in the IFN γ secretion. In the breast cancer model, P2Et and PD-L1 alone or in combination show antitumor effect with no clear additive effect. This study shows that combined therapy of P2Et and anti-PD-L1 can improve antitumor response in a melanoma model by activating the immune response and neutralizing immunosuppressive mechanisms.

The delay in cell death caused by the induction of autophagy by P2Et extract is essential for the generation of immunogenic signals in melanoma cells

P2Et extract obtained from the Caesalpinia spinosa plant is abundant in phenolic compounds such as gallic acid and ethyl gallate and can generate signals to activate the immune response by inducing a mechanism known as immunogenic cell death in murine models of breast cancer and melanoma. Immunogenic cell death involves mechanisms such as autophagy, which can be modulated by various natural compounds, including phenolic compounds with a structure similar to those found in P2Et extract. Here, we determine the role of autophagy in apoptosis and the generation of immunogenic signals using murine wild-type B16-F10 melanoma cells and cells with beclin-1 gene knockout. We show that P2Et extract and ethyl gallate induced autophagy, partially protecting tumor cells from death and promoting calreticulin exposure and the release of ATP. Although ethyl gallate showed a mechanism similar to that of P2Et, the induction of apoptosis and immunogenic signals was significantly weaker. In contrast, gallic acid-induced autophagy acted by blocking autophagic flux, which was associated with increased cell death. However, this compound did not induce any of the immunogenic death signals evaluated. Therefore, the complex extract has greater antitumor potential than isolated compounds. Here, we show that inducing autophagic flux with P2Et protects cancer cells from cell death and that this delay in cell death is required for the generation of immunogenic signals.

Targeting the tumor immune microenvironment with "nutraceuticals": From bench to clinical trials

The occurrence of immune effector cells in the tissue microenvironment during neoplastic progression is critical in determining tumor growth outcomes. On the other hand, tumors may also avoid immune system-mediated elimination by recruiting immunosuppressive leukocytes and soluble factors, which coordinate a tumor microenvironment that counteracts the efficiency of the antitumor immune response. Checkpoint inhibitor therapy results have indicated a way forward via activation of the immune system against cancer. Widespread evidence has shown that different compounds in foods, when administered as purified substances, can act as immunomodulators in humans and animals. Although there is no universally accepted definition of nutraceuticals, the term identifies a wide category of natural compounds that may impact health and disease statuses and includes purified substances from natural sources, plant extracts, dietary supplements, vitamins, phytonutrients, and various products with combinations of functional ingredients. In this review, we summarize the current knowledge on the immunomodulatory effects of nutraceuticals with a special focus on the cancer microenvironment, highlighting the conceptual benefits or drawbacks and subtle cell-specific effects of nutraceuticals for envisioning future therapies employing nutraceuticals as chemoadjuvants.

Streptococcus gallolyticus abrogates anti-carcinogenic properties of tannic acid on low-passage colorectal carcinomas

The tannase-producing Gram-positive bacterial species Streptococcus gallolyticus subsp. gallolyticus (Sgg) is an opportunistic pathogen of the human gut and strongly associated with colorectal cancer (CRC). A unique feature of Sgg is its ability to degrade tannic acids (TA). TA constitute an important part of the human diet with known anti-tumorigenic properties. Here, we examined whether Sgg is able to protect tumor cells from the toxic effect of TA and thus drive tumorigenesis indirectly. Human CRC cell lines (n = 8) were treated with increasing concentrations of TA. We confirmed the cytotoxic activity of TA in a dose-dependent manner. In virtually all cell lines, viability decreased significantly (>60% inhibition). Moreover, pyrogallol, the degradation product of TA, had no effect on the tested cell lines. This suggests a specific effect of TA. Cytotoxicity was due to necrosis and induction of senescence in residual cells. Finally, when TA was degraded by Sgg, the cytotoxic effect could be abolished. Tumor cells even responded with boosted cell proliferation, highlighting the impact of Sgg on CRC progression. We here provide another piece of evidence for the active interplay between Sgg and cancer preventive components. These data will help to move forward in designing concepts for therapeutic and eventually also prophylactic approaches to combat gastrointestinal malignancies.

Breast Tumor Cells Highly Resistant to Drugs Are Controlled Only by the Immune Response Induced in an Immunocompetent Mouse Model

Background: The tumor cells responsible for metastasis are highly resistant to chemotherapy and have characteristics of stem cells, with a high capacity for self-regeneration and the use of detoxifying mechanisms that participate in drug resistance. In vivo models of highly resistant cells allow us to evaluate the real impact of the immune response in the control of cancer. Materials and Methods: A tumor population derived from the 4T1 breast cancer cell line that was stable in vitro and highly aggressive in vivo was obtained, characterized, and determined to exhibit cancer stem cell (CSC) phenotypes (CD44⁺, CD24⁺, ALDH⁺, Oct4⁺, Nanog⁺, Sox2⁺, and high self-renewal capacity). Orthotopic transplantation of these cells allowed us to evaluate their in vivo susceptibility to chemo and immune responses induced after vaccination. Results: The immune response induced after vaccination with tumor cells treated with doxorubicin decreased the formation of tumors and macrometastasis in this model, which allowed us to confirm the immune response relevance in the control of highly chemotherapy-resistant ALDH⁺ CSCs in an aggressive tumor model in immunocompetent animals. Conclusions: The antitumor immune response was the main element capable of controlling tumor progression as well as metastasis in a highly chemotherapy-resistant aggressive breast cancer model.

Galla Rhois water extract inhibits lung metastasis by inducing AMPK‑mediated apoptosis and suppressing metastatic properties of colorectal cancer cells

Galla Rhois is a commonly used medicine in East Asia for the treatment of several diseases. However, the effects of Galla Rhois on the metastasis of colorectal cancer (CRC) and the underlying molecular mechanisms have not been studied. We investigated the anti-metastatic properties of Galla Rhois water extract (GRWE) on metastatic CRC cells. The effect of GRWE on the viability of colon 26 (CT26) cells was evaluated using WST-8 assay. Annexin V assay and western blot analysis were performed to elucidate the underlying molecular mechanisms involved in apoptosis. GRWE suppressed viability of CT26 cells by inducing apoptosis through the cleavage of caspase-3 and PARP, downregulation of caspase-8, caspase-9, Bcl-2 and Bcl-xL, and upregulation of Bax. Metastatic phenotypes such as epithelial-mesenchymal transition (EMT), migration, and invasion of CRC cells were investigated by real-time reverse transcription polymerase chain reaction, wound healing assay, and matrigel invasion assay, respectively. Non-cytotoxic concentrations of GRWE inhibited EMT in CRC cells by regulating the expression of EMT markers. GRWE attenuated cell migration and invasion through the inhibition of matrix metalloproteinase (MMP)-2 and MMP-9 activity. Moreover, GRWE suppressed colorectal lung metastasis in vivo, suggestive of its potential application for the treatment of colorectal metastasis.

Prophylactic vs. Therapeutic Treatment With P2Et Polyphenol-Rich Extract Has Opposite Effects on Tumor Growth

Polyphenols have tumoricidal effects via anti-proliferative, anti-angiogenic and cytotoxic mechanisms and have recently been demonstrated to modulate the immune response through their anti- or pro- oxidant activity. Nevertheless, it remains controversial whether antioxidant-rich supplements have real beneficial effects on health, especially in complex diseases such as cancer. We previously identified a polyphenol-rich extract obtained from Caesalpinia spinosa (P2Et) with anti-tumor activity in both breast carcinoma and melanoma. The present work evaluated the ability of P2Et extract to modulate the immune system in either the steady state or following tumor challenge. We found that the prophylactic treatment of healthy mice increased the number of CD4⁺ and CD8⁺ activated T, NK, regulatory T, dendritic and myeloid-derived suppressor cells in lymphoid organs together with a significant increase in plasma IL-6. Interestingly, this pre-conditioning of the host immune system with P2Et did not involve a protective effect against the control of tumor growth and metastasis in transplantable models of melanoma (B16) and breast cancer (4T1), but in contrast, a detrimental effect was observed in both models. We further demonstrated that this effect was at least partly due to an increase in regulatory T cells, myeloid-derived suppressor cells, and proinflammatory cytokines, with a concomitant decrease in CD4⁺ and CD8⁺ T cells. Taken together, these results suggest that the anti-tumor and immunomodulation properties of the P2Et extract critically depend on the presence of the tumor and might be mediated by the complex interactions between the tumor cells and the other components of the tumor microenvironment.

Comprehensive analysis of telomerase inhibition by gallotannin

Gallotannin (or tannic acid) is a naturally occurring compound that inhibits cell growth and activity of different DNA-polymerases, including telomerase. The purpose of the present study was to gain insight into the mechanism of telomerase inhibition by gallotannin. We determined that gallotannin inhibits telomerase in vitro with an half maximal inhibitory concentrations value of 130 nM, but it does not affect telomerase complex assembly and component levels in vivo. The inhibitory activity of gallotannin against telomerase provides an additional explanation for the anti-cancer activities of this compound.

Intestinal Permeability and Cellular Antioxidant Activity of Phenolic Compounds from Mango (Mangifera indica cv. Ataulfo) Peels

Mango (Mangifera indica cv. Ataulfo) peel contains bound phenolics that may be released by alkaline or acid hydrolysis and may be converted into less complex molecules. Free phenolics from mango cv. Ataulfo peel were obtained using a methanolic extraction, and their cellular antioxidant activity (CAA) and permeability were compared to those obtained for bound phenolics released by alkaline or acid hydrolysis. Gallic acid was found as a simple phenolic acid after alkaline hydrolysis along with mangiferin isomers and quercetin as aglycone and glycosides. Only gallic acid, ethyl gallate, mangiferin, and quercetin were identified in the acid fraction. The acid and alkaline fractions showed the highest CAA (60.5% and 51.5%) when tested at 125 µg/mL. The value of the apparent permeability coefficient (Papp) across the Caco-2/HT-29 monolayer of gallic acid from the alkaline fraction was higher (2.61 × 10⁻⁶ cm/s) than in the other fractions and similar to that obtained when tested pure (2.48 × 10⁻⁶ cm/s). In conclusion, mango peels contain bound phenolic compounds that, after their release, have permeability similar to pure compounds and exert an important CAA. This finding can be applied in the development of nutraceuticals using this important by-product from the mango processing industry.

Standardized Extract from Caesalpinia spinosa is Cytotoxic Over Cancer Stem Cells and Enhance Anticancer Activity of Doxorubicin

Cancer stem cells (CSC) are the primary cell type responsible for metastasis and relapse. ABC-transporters are integral membrane proteins involved in the translocation of substrates across membranes protecting CSC from chemotherapeutic agents. A plant extract derived from C. spinosa (P2Et) previously investigated for its antitumor activity has been shown to reduce lung and spleen metastasis in mice that have been transplanted with breast cancer cells, suggesting that P2Et has a significant activity against cancer stem cells (CSC). P2Et extract was thoroughly characterized by HPLC/MS. The cytotoxicity of P2Et extract was evaluated using a MTT assay in human and murine cell lines with different profiles of resistance, by Pgp overexpression or by enrichment in cancer stem cells. The synergistic effect of P2Et with doxorubicin was evaluated in vitro in several cell lines and in vivo in mice transplanted with TS/A cells, a highly resistant cell line and enriched in CD44[Formula: see text]CD24[Formula: see text]CSC. The chromatographic fingerprint of P2Et extract revealed 13 gallotannins. We also found that P2Et extract was cytotoxic to cells regardless of their resistant phenotype. Similarly, complementary activities were observed as drug efflux reversion and antioxidant activity. Short-treatment with P2Et extract, revealed a synergistic effect with doxorubicin in resistant cell lines. In vivo the P2Et increases mice survival in a TS/A breast cancer model associated with augmentation of calreticulin expression. Our results suggest that P2Et treatment could be used as adjuvant along with conventional chemotherapy to treat tumors with a MDR phenotype or with high frequency of CSC.

Standardized Extract from Caesalpinia spinosa is Cytotoxic Over Cancer Stem Cells and Enhance Anticancer Activity of Doxorubicin

Cancer stem cells (CSC) are the primary cell type responsible for metastasis and relapse. ABC-transporters are integral membrane proteins involved in the translocation of substrates across membranes protecting CSC from chemotherapeutic agents. A plant extract derived from C. spinosa (P2Et) previously investigated for its antitumor activity has been shown to reduce lung and spleen metastasis in mice that have been transplanted with breast cancer cells, suggesting that P2Et has a significant activity against cancer stem cells (CSC). P2Et extract was thoroughly characterized by HPLC/MS. The cytotoxicity of P2Et extract was evaluated using a MTT assay in human and murine cell lines with different profiles of resistance, by Pgp overexpression or by enrichment in cancer stem cells. The synergistic effect of P2Et with doxorubicin was evaluated in vitro in several cell lines and in vivo in mice transplanted with TS/A cells, a highly resistant cell line and enriched in CD44[Formula: see text]CD24[Formula: see text]CSC. The chromatographic fingerprint of P2Et extract revealed 13 gallotannins. We also found that P2Et extract was cytotoxic to cells regardless of their resistant phenotype. Similarly, complementary activities were observed as drug efflux reversion and antioxidant activity. Short-treatment with P2Et extract, revealed a synergistic effect with doxorubicin in resistant cell lines. In vivo the P2Et increases mice survival in a TS/A breast cancer model associated with augmentation of calreticulin expression. Our results suggest that P2Et treatment could be used as adjuvant along with conventional chemotherapy to treat tumors with a MDR phenotype or with high frequency of CSC.

Immune-system-dependent anti-tumor activity of a plant-derived polyphenol rich fraction in a melanoma mouse model

Recent findings suggest that part of the anti-tumor effects of several chemotherapeutic agents require an intact immune system. This is in part due to the induction of immunogenic cell death. We have identified a gallotannin-rich fraction, obtained from Caesalpinia spinosa (P2Et) as an anti-tumor agent in both breast carcinoma and melanoma. Here, we report that P2Et treatment results in activation of caspase 3 and 9, mobilization of cytochrome c and externalization of annexin V in tumor cells, thus suggesting the induction of apoptosis. This was preceded by the onset of autophagy and the expression of immunogenic cell death markers. We further demonstrate that P2Et-treated tumor cells are highly immunogenic in vaccinated mice and induce immune system activation, clearly shown by the generation of interferon gamma (IFN-γ) producing tyrosine-related protein 2 antigen-specific CD8+ T cells. Moreover, the tumor protective effects of P2Et treatment were abolished in immunodeficient mice, and partially lost after CD4 and CD8 depletion, indicating that P2Et's anti-tumor activity is highly dependent on immune system and at least in part of T cells. Altogether, these results support the hypothesis that the gallotannin-rich fraction P2Et's anti-tumor effects are mediated to a great extent by the endogenous immune response following to the exposure to immunogenic dying tumor cells.

AR, Yavvari PS, Srivastava A, Bajaj A. Interactions governing the entrapment of anticancer drugs by low-molecular-weight hydrogelator for drug delivery applications

We present the effect of size, charge, and hydrophobicity of anticancer drugs on their drug encapsulation efficacy in anl-alanine-based small-molecule hydrogelator.

Multifunctional T Lymphocytes Generated After Therapy With an Antitumor Gallotanin-Rich Normalized Fraction Are Related to Primary Tumor Size Reduction in a Breast Cancer Model

Natural compounds are promising sources for anticancer therapies because of their multifunctional activity and low toxicity. Although the host immune response (IR) is clearly implicated in tumor control, the relationship between natural therapies and IR has not yet been elucidated. The present work evaluates IR induction after treatment with a gallotannin-rich fraction from Caesalpinia spinosa (P2Et). Breast tumor 4T1 cells were used to evaluate antitumor properties and IR activation. Apoptosis and expression of immunogenic cell death (ICD) markers were assessed in vitro, whereas IR and postvaccination tumor evolution were assessed in vivo. P2Et fraction induced apoptotic cell death, displaying phosphatidylserine externalization and DNA fragmentation. ICD markers such as calreticulin, high-mobility group box 1 translocation from nuclei to cytoplasm, and ATP secretion were observed. Primary tumor control was improved by vaccination with P2Et-pretreated 4T1 cells (t-P2Et), yielding long-lasting ex vivo multifunctional CD4+ and CD8+ T lymphocytes (interleukin [IL]-2+, tumor necrosis factor [TNF]-α+, interferon [IFN]-γ+) that secrete IL-2, TNF-α, IL-4, IL-5, and IFN-γ after specific 4T1 cell stimulation. The present study constitutes the first demonstration of a long-lasting antitumor IR induction and primary tumor reduction induced by a complex natural fraction. These data reveal the potential use of this fraction as an adjuvant in breast cancer treatment.

Multifunctional T Lymphocytes Generated After Therapy With an Antitumor Gallotanin-Rich Normalized Fraction Are Related to Primary Tumor Size Reduction in a Breast Cancer Model

Natural compounds are promising sources for anticancer therapies because of their multifunctional activity and low toxicity. Although the host immune response (IR) is clearly implicated in tumor control, the relationship between natural therapies and IR has not yet been elucidated. The present work evaluates IR induction after treatment with a gallotannin-rich fraction from Caesalpinia spinosa (P2Et). Breast tumor 4T1 cells were used to evaluate antitumor properties and IR activation. Apoptosis and expression of immunogenic cell death (ICD) markers were assessed in vitro, whereas IR and postvaccination tumor evolution were assessed in vivo. P2Et fraction induced apoptotic cell death, displaying phosphatidylserine externalization and DNA fragmentation. ICD markers such as calreticulin, high-mobility group box 1 translocation from nuclei to cytoplasm, and ATP secretion were observed. Primary tumor control was improved by vaccination with P2Et-pretreated 4T1 cells (t-P2Et), yielding long-lasting ex vivo multifunctional CD4+ and CD8+ T lymphocytes (interleukin [IL]-2+, tumor necrosis factor [TNF]-α+, interferon [IFN]-γ+) that secrete IL-2, TNF-α, IL-4, IL-5, and IFN-γ after specific 4T1 cell stimulation. The present study constitutes the first demonstration of a long-lasting antitumor IR induction and primary tumor reduction induced by a complex natural fraction. These data reveal the potential use of this fraction as an adjuvant in breast cancer treatment.

A Petiveria alliacea standardized fraction induces breast adenocarcinoma cell death by modulating glycolytic metabolism

ETHNOPHARMACOLOGICAL RELEVANCE

Folk medicine uses aqueous and alcoholic extracts from Petiveria alliacea (Phytolaccaceae) in leukemia and breast cancer treatment in the Caribbean, Central and South America. Herein, we validated the biological activity of a Petiveria alliacea fraction using a metastatic breast adenocarcinoma model (4T1).

MATERIALS AND METHODS

Petiveria alliacea fraction biological activity was determined estimating cell proliferation, cell colony growth capacity and apoptosis (caspase-3 activity, DNA fragmentation and mitochondrial membrane potential) in 4T1 cells. Petiveria alliacea was used at IC₅₀ concentration (29 µg/mL) and 2 dilutions below, doxorubicin at 0.27 µg/mL (positive control) and dibenzyl disulfide at 2.93 µg/mL (IC50 fraction marker compound). Proteomic estimations were analyzed by LC-MS-MS. Protein level expression was confirmed by RT-PCR. Glucose and lactate levels were measured by enzymatic assays. LD50 was established in BALB/c mice and antitumoral activity evaluated in mice transplanted with GFP-tagged 4T1 cells. Mice were treated with Petiveria alliacea fraction via I.P (182 mg/kg corresponding to 1/8 of LD₅₀ and 2 dilutions below).

RESULTS

Petiveria alliacea fraction in vitro induces 4T1 cells apoptosis, caspase-3 activation, DNA fragmentation without mitochondria membrane depolarization, and decreases cell colony growth capacity. Also, changes in glycolytic enzymes expression cause a decrease in glucose uptake and lactate production. Fraction also promotes breast primary tumor regression in BALB/c mice transplanted with GFP-tagged 4T1 cells.

CONCLUSION

A fraction of Petiveria alliacea leaves and stems induces in vitro cell death and in vivo tumor regression in a murine breast cancer model. Our results validate in partly, the traditional use of Petiveria alliacea in breast cancer treatment, revealing a new way of envisioning Petiveria alliacea biological activity. The fraction effect on the glycolytic pathway enzymes contributes to explain the antiproliferative and antitumor activities.

Suppression of E-cadherin mediates gallotannin induced apoptosis in Hep G2 hepatocelluar carcinoma cells

Though gallotannin was known to have anti-oxidant and antitumor activity, the underlying antitumor mechanism of gallotannin still remains unclear. Thus, in the present study, antitumor mechanism of gallotannin was elucidated in hepatocellular carcinoma cells. Gallotannin significantly exerted cytotoxicity against Hep G2 and Chang hepatocellular carcinoma cells with the accumulation of the sub-G1 population and increase of terminal deoxynucleotidyltransferasedUTP nick end labeling (TUNEL) positive cells as an apoptotic feature. Also, gallotannin attenuated the expression of pro-caspase9, pro-caspase3, Bcl2 and integrin β1 and cleaved poly(ADP)-ribose polymerase (PARP) in Hep G2 and Chang cancer cells. Furthermore, gallotannin suppressed cell repair motility by wound healing assay and also inhibited cell adhesion in Hep G2 cells. Of note, gallotannin attenuated the expression of epithelial cadherin (E-cadherin) to form cell-cell adhesion from the early stage, and also beta-catenin at late phase in Hep G2 cells. Consistently, Immunofluorescence assay showed that E-cadherin or β-catenin expression was suppressed in a time dependent manner by gallotannin. Furthermore, silencing of E-cadherin by siRNA transfection method enhanced PAPR cleavage, caspase 3 activation and sub G1 population and attenuated the cell adhesion induced by gallotannin in Hep G2 cells. Overall, our findings demonstrate that the disruption of cell adhesion junction by suppression of E-cadherin mediates gallotannin enhanced apoptosis in Hep G2 liver cancer cells.

Silibinin inhibits accumulation of myeloid-derived suppressor cells and tumor growth of murine breast cancer

Myeloid-derived suppressor cells (MDSC)s increase in blood and accumulate in the tumor microenvironment of tumor-bearing animals, contributing to immune suppression in cancer. Silibinin, a natural flavonoid from the seeds of milk thistle, has been developed as an anti-inflammatory agent and supportive care agent to reduce the toxicity of cancer chemotherapy. The goals of this study were to evaluate the effect of silibinin on MDSCs in tumor-bearing mice and antitumor activity of silibinin in a mouse model of breast cancer. 4T1 luciferase-transfected mammary carcinoma cells were injected into in the mammary fat pad female BALB/c mice, and female CB17-Prkdc Scid/J mice. Silibinin treatment started on day 4 or day 14 after tumor inoculation continued every other day. Tumor growth was monitored by bioluminescent imaging (BLI) measuring total photon flux. Flow cytometry measured total leukocytes, CD11b⁺ Gr-1⁺ MDSC, and T cells in the blood and tumors of tumor-bearing mice. The effects of silibinin on 4T1 cell viability in vitro were measured by BLI. Treatment with silibinin increased overall survival in mice harboring tumors derived from the 4T1-luciferase breast cancer cell line, and reduced tumor volumes and numbers of CD11b⁺Gr-1⁺ MDSCs in the blood and tumor, and increased the content of T cells in the tumor microenvironment. Silibinin failed to inhibit tumor growth in immunocompromised severe combined immunodeficiency mice, supporting the hypothesis that anticancer effect of silibinin is immune-mediated. The antitumor activity of silibinin requires an intact host immune system and is associated with decreased accumulation of blood and tumor-associated MDSCs.

[Effect of miskleron (clofibrate) on dimethylhydrazine induction of intestinal tumors in rats]

In this review, we report on the complexity of breast cancer stem cells as key cells in the emergence of a chemoresistant tumor phenotype, and as a result, the appearance of distant metastasis in breast cancer patients. The search for mechanisms that increase sensitivity to chemotherapy and also allow activation of the tumor-specific immune response is of high priority. As we observed throughout this review, natural products isolated or in standardized extracts, such as P2Et or others, could act synergistically, increasing tumor sensitivity to chemotherapy, recovering the tumor microenvironment, and participating in the induction of a specific immune response. This, in turn, would lead to the destruction of cancer stem cells and the decrease in metastasis.

Source of Data: Relevant studies were found using the following keywords or medical subject headings (MeSH) in PubMed, and Google Scholar: “immune response” and “polyphenols” and “natural products” and “BCSC” and “therapy” and “metabolism” and “immunogenic cell death.” The focus was primarily on the most recent scientific publication.