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PMC10968586
In the next paragraphs, we discuss the role of OLE and HT absorption, bioavailability and toxicity to non-cancer cells, OLE and HT interaction with chemotherapy drugs, OLE- and HT-mediated repercussions on drug metabolism, and OLE and HT antioxidant activity in the context of chemotherapy-induced oxidative stress as de...
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PMC10968586
Factors influencing OLE and HT effects in human cancers are reported in Figure 2.
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PMC10968586
Information about OLE and HT absorption through the digestive tract and bioavailability is limited, and often arises from a combination of experimental proofs obtained from humans and animal models.
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PMC10968586
After ingestion, OLE remains mostly stable in the acid gastric environment, although non-enzymatic hydrolysis may account for an increased amount of HT reaching the small intestine.
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PMC10968586
OLE is poorly absorbed through the small intestine (mainly via diffusion), as demonstrated in rats and humans, enters systemic circulation, undergoes sulphate and glucuronide conjugation and/or enzymatic conversion in HT, and is eliminated in urine mainly as aglycon and glucuronide derivatives .
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PMC10968586
In the large intestine, OLE is metabolized by gut microbiota, producing HT .
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PMC10968586
After ingestion, HT is more largely absorbed in the intestine by diffusion, is mainly metabolized into glucuronide and sulphate conjugates, and is excreted in urine mostly in its glucuronide conjugated form .
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PMC10968586
For both OLE and HT (and their metabolites), the maximum excretion rate is reached in 4 h in humans .
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PMC10968586
All these aspects may represent a potential source of difficulties if the objective is achieving and maintaining pharmacologically relevant concentrations of OLE and HT in plasma after ingestion.
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PMC10968586
Whenever performing a critical evaluation of OLE and HT availability, data from animal models should be taken into account with caution, since it has been demonstrated that the rate of excretion of HT differs between humans and rats (being more rapid in humans) .
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PMC10968586
Thus, only data related to OLE and HT plasma concentrations in humans are listed in this section.
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PMC10968586
In a group of volunteers, the efficacy of OLE delivery was assayed for liquid and capsule preparations, each containing a lower (64 mg total olive phenols, with 51.1 mg OLE) or a higher (96 mg total, with 76.6 mg OLE) dose.
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PMC10968586
The best performance was offered by higher dose liquid preparation, with a mean peak of plasma OLE ± S.D. = 3.55 ± 2.27 ng/mL and a mean time to peak ± S.D. = 20 ± 12 min, whereas the worst OLE peak plasma values were detected for the lower dose capsule preparation (mean peak ± S.D. = 0.52 ± 0.24 ng/mL, mean time to pe...
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PMC10968586
In humans, the assumption of 5 mg HT added to extra virgin olive oil produced a plasma peak of 3.79 ng/mL after 30 min, followed by a rapid decline in HT plasma concentration (minimum reached value < 2 ng/mL after 240 min) .
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PMC10968586
This result matched another report documenting that the consumption of HT-enriched biscuits (containing 5.25 mg HT) determined the appearance of HT metabolites in the volunteers’ plasma between 30 min and 1 h .
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PMC10968586
A similar pharmacokinetic effect was reported in other experimental settings using olive-derived watery supplements as a source of HT .
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PMC10968586
The ingestion of 40 mL of high (366 mg/kg)-phenolic-compound-content olive oil led to a plasma HT concentration peak of ≈15 μM (mean time to peak ± S.D. = 0.91 ± 0.84 h, mean estimated elimination half-life ± S.D. = 3.00 ± 1.46 h), whereas the same amount of low- (2.7 mg/kg) and medium (164 mg/kg)-phenolic-compound-con...
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PMC10968586
The assumption of 25 mL of extra virgin olive oil led to a maximum plasma concentration = 4.4 ng/mL, (time to peak = 0.25 h) , and the ingestion of 25 mL of low-phenolic-content (10 mg/kg), moderate-phenolic-content (133 mg/kg), and high-phenolic-content (486 mg/kg) olive oil produce a plasma HT peak of ≈5 nM, 25 nM, a...
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PMC10968586
On the basis of these pieces of data, it becomes evident that cytotoxicity and anti-cancer effects of OLE and HT were recorded at concentrations largely exceeding those reachable with diet/olive oil consumption, and OLE and HT pharmacokinetics does not match the requested treatment duration to exert an anti-proliferati...
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PMC10968586
Thus, it is difficult to imagine how OLE and HT may be used as cancer-preventive/treating agents if the route of administration is ingestion.
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PMC10968586
Also, given that both phenols are extensively metabolized and rapidly excreted, the safety and efficacy of other routes of administration (e.g., intravenous) should be assessed in detail.
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PMC10968586
However, even at high concentrations, OLE and HT seem to be selectively cytotoxic for cancer cells, with no or negligible/minimal effects on non-cancer cells, as demonstrated for embryonic rat cardiomyoblasts H9c2(2-1), human breast epithelial cell line MCF-10A , nonmalignant human bronchial epithelial BEAS-2B cell lin...
[ { "end": 213, "label": "CellLine", "start": 209, "text": "H9c2" }, { "end": 261, "label": "CellLine", "start": 254, "text": "MCF-10A" }, { "end": 311, "label": "CellLine", "start": 304, "text": "BEAS-2B" }, { "end": 359, "label": "CellLine", "s...
PMC10968586
Thus, OLE and HT are generally considered safe on the basis of experimental data, despite sporadic reports against the trend, as happened for HT, which proved to be toxic for human non-tumorigenic pancreas cells HPDE and human normal prostate RWPE-1 cells .
[ { "end": 216, "label": "CellLine", "start": 212, "text": "HPDE" }, { "end": 249, "label": "CellLine", "start": 243, "text": "RWPE-1" } ]
PMC10968586
The evaluation of OLE and HT safety profile in cancer patients is still pending.
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PMC10968586
Some experimental proof has demonstrated that OLE and HT may potentiate the effect of both routinely employed and new potential anti-cancer drugs .
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PMC10968586
In human melanoma cell line A375, the combination of 250 μM OLE with alkylating agent dacarbazine was more effective in reducing cell viability than dacarbazine alone .
[ { "end": 32, "label": "CellLine", "start": 28, "text": "A375" } ]
PMC10968586
In female breast cancer patients undergoing neoadjuvant chemotherapy, orally administered 15 mg/kg HT determined a significant decrease in plasma levels of TIMP-1 during treatment with epirubicin and cyclophosphamide .
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PMC10968586
In an in vivo model of tumor xenograft (triple negative MDA-MB-231 cell line) in BALB/c OlaHsd-foxn1 mice, peritoneally injected 50 mg/kg OLE for 4 weeks exhibited a synergistic effect with doxorubicin on inhibition of tumor growth and induction of apoptosis .
[ { "end": 66, "label": "CellLine", "start": 56, "text": "MDA-MB-231" }, { "end": 87, "label": "CellLine", "start": 81, "text": "BALB/c" } ]
PMC10968586
Combination of paclitaxel with HT reduced MCF-7 and MDA-MB-231 cell viability in vitro, and tumor volume in breast cancer-bearing Sprague–Dawley rats (in vivo injected HT dose = 0.5 mg/kg/day) .
[ { "end": 47, "label": "CellLine", "start": 42, "text": "MCF-7" }, { "end": 62, "label": "CellLine", "start": 52, "text": "MDA-MB-231" } ]
PMC10968586
In HT-29 and WiDr colorectal cancer cell lines, combination of 10 μM HT and monoclonal anti-epidermal growth factor receptor (EGFR) antibody cetuximab reduced cell growth, both in the presence and in the absence of epidermal growth factor (EGF) stimulation, inducing G1/S and G2/M phase cell cycle arrest .
[ { "end": 8, "label": "CellLine", "start": 3, "text": "HT-29" }, { "end": 17, "label": "CellLine", "start": 13, "text": "WiDr" } ]
PMC10968586
In human osteosarcoma MG-63 cell line, 20 μg/mL (≈37 μM) OLE had an additive effect on anthracycline Adriamycin-induced reduction in cell viability, with a mechanism that did not alter the G2/M phase blockade elicited by Adriamycin .
[ { "end": 27, "label": "CellLine", "start": 22, "text": "MG-63" } ]
PMC10968586
Similarly, in 143B osteosarcoma cells, OLE showed a synergistic, antiproliferative, and anti-migratory effect in combination with estradiol metabolite 2-methoxyestradiol at all OLE concentrations tested (1–250 μM for proliferation, and 100 μM for wound healing assay) .
[ { "end": 18, "label": "CellLine", "start": 14, "text": "143B" } ]
PMC10968586
On the contrary, HT did not modify doxorubicin-mediated growth inhibition of human osteosarcoma cells U-2 OS .
[ { "end": 108, "label": "CellLine", "start": 102, "text": "U-2 OS" } ]
PMC10968586
In neuroblastoma cells T98G, 277.5 μM and 555 μM OLE showed a synergistic effect with alkylating agent temozolomide on cell viability, increasing the expression of miRNAs involved in tumor growth suppression, mainly Let-7d .
[ { "end": 27, "label": "CellLine", "start": 23, "text": "T98G" } ]
PMC10968586
OLE and HT may also magnify the efficacy of other types of cancer treatment.
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PMC10968586
In nasopharyngeal cancer cell line HNE1 and HONE1, 200 μM OLE enhanced cell radiosensitivity in vitro and in vivo after injection in BALB/C nude mice, with a mechanism involving OLE-dependent removal of HIF-1α hypoxic repression exerted at miR-519d promoter region, upregulation of miR-519d, and miR-519d targeting of DN...
[ { "end": 39, "label": "CellLine", "start": 35, "text": "HNE1" }, { "end": 49, "label": "CellLine", "start": 44, "text": "HONE1" }, { "end": 139, "label": "CellLine", "start": 133, "text": "BALB/C" } ]
PMC10968586
Despite these encouraging results, since both OLE and HT may act as transcriptional regulators and are extensively metabolized by the liver (see sections above), a careful analysis of the effects of both phenols on phase I and phase II enzyme kinetics and expression should be performed before considering the use of OLE...
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PMC10968586
Preliminary data obtained in human liver microsomes point towards OLE-mediated inhibition of CY3A and CYP1A2 activity .
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PMC10968586
On the contrary, a study performed in 129/Sv WT and Ppara-null mice demonstrated that OLE (ingested with food, thus absorbed through the intestinal wall) stimulated the transcription of cytochrome P450 genes Cyp1a1, Cyp1a2, Cyp1b1, Cyp3a14, Cyp3a25, Cyp2c29, Cyp2c44, Cyp2d22, and Cyp2e1 in the liver, with a mechanism m...
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PMC10968586
Studies defining the effects of OLE and HT on the expression of and interaction with phase I and phase II enzymes are still missing, but they should be considered absolutely necessary in order to determine if OLE and HT are able to modify the metabolism of other drugs.
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PMC10968586
Besides their possible synergic/additive actions, OLE and HT might also be seen as useful support agents during cancer treatment.
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PMC10968586
A lot of experimental data in vivo and in vitro have definitively demonstrated the ROS scavenger ability of OLE and HT, which can also act on antioxidant cellular mechanisms restoring ROS homeostasis, including promotion of the increase in reduced glutathione levels (GSH), depletion of lipid peroxidation product malond...
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PMC10968586
Radical and non-radical ROS (including hydrogen peroxide H2O2, superoxide anion radical O2, and hydroxyl radical OH) may have a pro-tumorigenic effect; they are involved in cancer insurgence determining DNA damage, genomic instability, and interference with signalling and metabolic pathways, enhance cell proliferation ...
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PMC10968586
However, if ROS concentration overcomes cancer cell defenses against oxidative stress and damage, or cancer cell-produced ROS balance is perturbated, ROS may account for fatal cell damage and trigger apoptosis .
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PMC10968586
This may explain the fact that the mechanism of action of some common cancer treatments (e.g., radiation, inorganic compounds, tyrosine kinase inhibitors, monoclonal antibodies, protease inhibitors, pyrimidine analogues, alkylating agents, and anthracyclines) relies on oxidative stress and ROS-dependent apoptosis .
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PMC10968586
OLE and HT cytotoxic actions themselves in part depend on ROS generation ; moreover, 200 μM OLE reduced HIF-1α mRNA and protein levels in HNE-1 and HONE-1 nasopharyngeal cancer cell lines , and pro-apoptotic OLE concentration corresponding to 100 μM was able to increase ROS production in MDA-MB-231 cell line, with the ...
[ { "end": 143, "label": "CellLine", "start": 138, "text": "HNE-1" }, { "end": 154, "label": "CellLine", "start": 148, "text": "HONE-1" }, { "end": 299, "label": "CellLine", "start": 289, "text": "MDA-MB-231" } ]
PMC10968586
ROS-mediated damage at least in part accounts for chemotherapy-dependent toxicity detected at the tissue level on non-cancer cells .
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PMC10968586
However, OLE and HT have shown an important ability to mitigate the toxicity elicited by chemotherapeutic agents mainly through their largely demonstrated antioxidant and ROS scavenger activity.
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PMC10968586
In fact, in vivo, 50 mg/kg, 100 mg/kg, and 200 mg/kg OLE showed a dose-dependent antioxidant activity, accounting for amelioration of cisplatin-induced pancreatic, liver, lung, and stomach damage in Spraque–Dawley rats .
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PMC10968586
In the same in vivo model of cisplatin-induced oxidative stress, 50 mg/kg, 100 mg/kg, and 200 mg/kg OLE improved anemia, thrombocytopenia, and leukopenia .
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PMC10968586
In cyclophosphamide- and epirubicin-induced toxicity in Sprague–Dawley rats, four cycles of 150 mg/kg/week OLE reduced lipid peroxidation and increased the activity of antioxidant enzymes in heart, kidney, and liver .
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PMC10968586
Moreover, in a model of cyclophosphamide-induced immunosuppression in broilers, a solution containing 200 mg/L HT reduced duodenal MDA levels while increasing the activity of antioxidant enzymes .
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PMC10968586
In vitro, 50 μM and 70 μM HT reduced doxorubicin-mediated toxicity in embryonic rat cardiomyoblasts H9c2(2-1) after 48 h incubation.
[ { "end": 104, "label": "CellLine", "start": 100, "text": "H9c2" } ]
PMC10968586
Also, 24 and 48 h incubation with 50 μM HT reduced doxorubicin-dependent intracellular ROS accumulation, increasing SOD2 levels and protecting cells from doxorubicin-induced apoptosis .
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PMC10968586
OLE- and HT-dependent redox homeostasis restoration might represent a potential issue with respect to OLE and HT use at nutritionally relevant concentrations as both anticancer drugs and detoxicating agents (especially during chemotherapy).
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PMC10968586
Low concentrations of both OLE and HT (10 μM) protected HL-60 and PBMCs from H2O2-induced DNA damage, and lymphocytes from PMA-stimulated monocyte-mediated oxidative DNA damage .
[ { "end": 61, "label": "CellLine", "start": 56, "text": "HL-60" } ]
PMC10968586
This piece of information sounds particularly alarming, since arsenic trioxide (As2O3) is one of the agents utilized to treat acute promyelocytic leukemia, especially in combinatory first-line therapy, and its mechanism of action relies on ROS increase .
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PMC10968586
Incubation with 30 μM HT for 48 h was not sufficient to reduce viability of Hep3B cells, but significantly improved cellular antioxidant capacities .
[ { "end": 81, "label": "CellLine", "start": 76, "text": "Hep3B" } ]
PMC10968586
Similarly, 5–200 μM HT was ineffective as a cytotoxic reagent, but reduced the level of oxidative stress in MCF-7 cells after 16 h incubation .
[ { "end": 113, "label": "CellLine", "start": 108, "text": "MCF-7" } ]
PMC10968586
Erastin is a ferropoptosis inducer that is currently under evaluation as an anti-cancer treatment .
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PMC10968586
In ovarian carcinoma HEY cells, 100 μM OLE was not able to affect cell viability, but acted as an antioxidant, decreasing endogenous and erastin-dependent LIP and ROS levels, preventing erastin-dependent ROS accumulation in mytochondria and increasing glutathione peroxidase 4 (GPX4) levels that were reduced by erastin ...
[ { "end": 24, "label": "CellLine", "start": 21, "text": "HEY" } ]
PMC10968586
It remains to be demonstrated if nutritionally relevant and/or non-cytotoxic concentrations of OLE and HT may offer a survival advantage to neoplastic cells.
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PMC10968586
A similar scenario has been described for other antioxidants (e.g., N-acetyl-L-cysteine, alpha-tocopherol and carotenoids), which showed a pro-tumorigenic action by exerting beneficial effects on cancer cells .
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PMC10968586
It will be fundamental to deepen these pieces of data in order to rule out the chance that OLE and HT may promote cancer growth and metastasis.
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PMC10968586
Another risk factor for tumorigenesis is inflammation.
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PMC10968586
ROS imbalance itself may drive inflammation, inducing the production of pro-inflammatory cytokines interleukin-1 (IL-1), IL-6, IL-8, and tumor necrosis factor-α (TNF-α) .
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PMC10968586
Persisting (chronic) or poorly controlled inflammation may directly promote tumorigenesis due to the action of ROS and the recruitment of immune cells triggering the release of growth signals and the activation of tissue repair mechanisms.
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PMC10968586
After cancer insurgence, the production of inflammatory mediators sustained by cancer cells and surrounding actors (tissue macrophages, cancer-associated fibroblast, infiltrating immune cells, and endothelial cells, among the others) contributes to the creation of an environment favoring immune evasion, cell survival, ...
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PMC10968586
Chemotherapy may also account for an exacerbation of inflammation, whose biological meaning is poorly understood, being recognized as immune-activating as well as a contributor to the failure of the therapeutic regimen .
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PMC10968586
OLE and HT exhibit an anti-inflammatory activity that has been demonstrated in multiple in vivo and in vitro models, although some experimental variables related to the timing of administration of inflammatory stimuli might have affected the reproducibility of the results, mainly in vitro, and nutritionally relevant co...
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PMC10968586
Proof of OLE and HT modulation of inflammation in cancer cells has been obtained mostly from colorectal cancer.
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PMC10968586
In an in vivo model of AOM/DSS-induced colorectal cancer in C57BL/6 mice, 50 mg/kg and 100 mg/kg OLE reduced IL-6, TNF-α, and IFN-γ colon tissue levels, as well as COX-2 levels .
[ { "end": 67, "label": "CellLine", "start": 60, "text": "C57BL/6" } ]
PMC10968586
Treatment of HCT116 and LoVo cells with 0.0154 mg/mL (≈100 μM) HT and 0.0231 mg/mL (≈150 μM) HT, respectively, for 72 h reduced phosphorylation of NF-κB p65, in turn leading to a reduction in pro-inflammatory cytokines TNF-α and IL-8 at both mRNA and protein levels.
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PMC10968586
HT-dependent anti-inflammatory effect was also mediated by HT-elicited increase in protein levels of PPARγ.
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PMC10968586
In addition, HT acted as a PPARγ agonist, promoting its transcriptional activity .
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PMC10968586
In HT-29 cell line, 100–400 μM reduced TNF-α-induced NF-κB activation in a dose-dependent manner .
[ { "end": 8, "label": "CellLine", "start": 3, "text": "HT-29" } ]
PMC10968586
In in vitro models, the frame appears completely different.
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PMC10968586
The only HT concentrations that elicited a reduction in IL-6 levels were 80 μM for HepG2 and 30 μM for Hep3B.
[ { "end": 88, "label": "CellLine", "start": 83, "text": "HepG2" }, { "end": 108, "label": "CellLine", "start": 103, "text": "Hep3B" } ]
PMC10968586
HT doses of 100 μM and 200 μM in HepG2 and 80 μM, 100 μM, and 200 μM in Hep3B cells produced an increase in IL-6 release .
[ { "end": 38, "label": "CellLine", "start": 33, "text": "HepG2" }, { "end": 77, "label": "CellLine", "start": 72, "text": "Hep3B" } ]
PMC10968586
Treatment of K562 cells with 100 μM HT produced transcriptional effects including the downregulation of IL-10 receptor and the upregulation of inflammatory mediators IL-6 and IL-8 .
[ { "end": 17, "label": "CellLine", "start": 13, "text": "K562" } ]
PMC10968586
OLE and HT may participate in control of cancer-associated and chemotherapy-dependent tissue inflammation by acting on non-tumor cells.
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PMC10968586
As demonstrated in vivo, treatment of BALB/cN mice with 5, 10, and 20 mg/kg OLE suppressed signs of cisplatin-induced renal inflammation, including tissue modulation of TNF-α levels .
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PMC10968586
Four cycles of 150 mg/kg/week OLE in Sprague–Dawley rats reduced serum TNF-α and IL-6 in an experimental model of epirubicin and cyclophosphamide toxicity .
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PMC10968586
In a model of cyclophosphamide-induced immunosuppression in broilers, a solution containing 200 mg/L HT promoted the duodenal expression of anti-inflammatory cytokines IL-4 and IL-10 .
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PMC10968586
It remains to be assessed if such a modulatory activity is able to contribute to the immunosuppressant environment surrounding cancer cells.
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PMC10968586
From the analysis of the literature reported in this review, it becomes evident that the multifaceted nature of OLE and HT interaction with molecular mediators in cancer cells and non-cancer tissues determines the need for safe strategies to improve OLE and HT bioavailability and delivery, also offering a more stable a...
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PMC10968586
Different approaches have been evaluated to reach this objective through the development of OLE and HT derivatives or carrier systems.
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PMC10968586
For example, peracetylated OLE had a stronger anti-proliferative and antioxidant activity than OLE in thyroid and breast cancer in vitro ; iron oxide nanoparticles coated with glucose and conjugated with OLE showed a notable cytotoxic action against colorectal cancer cell line SW480 ; chitosan nanoencapsulation of HT w...
[ { "end": 283, "label": "CellLine", "start": 278, "text": "SW480" }, { "end": 709, "label": "CellLine", "start": 702, "text": "SH-SY5Y" } ]
PMC10968586
Anyway, it would be highly recommendable to address future OLE- and HT-specific research directions towards the exploration of the true effect of nutritionally relevant concentrations of these phenols (or OLE and HT concentrations that can realistically be maintained in plasma) on cancer cells, since even most recent e...
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PMC10968586
Up to now, conclusive studies assessing the influence of nutritionally relevant concentrations of OLE and HT on tumor insurgence and expansion, as well as proof of the absence of OLE- and HT-mediated alterations of chemotherapy metabolism, are still missing.
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PMC10968586
Another important reason for concern is represented by OLE and HT context-dependent dual action as both antioxidant and pro-oxidant agents, since such a behavior may alter the efficacy of cancer treatment in unexplored ways.
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PMC10968586
Also, OLE and HT modulatory activity on immune cells deserves further investigation.
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PMC10968586
Currently, neither OLE nor HT could be safely considered as cancer-preventive agents or drugs for combinatory therapies without excluding the possibility that nutritionally relevant concentrations of these compounds might facilitate neoplastic cell expansion or even treatment escape.
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PMC12730593
Isoflavones are natural compounds abundantly found in soybeans, recognized for their anticancer potential, primarily through their activity as phytoestrogens, which inhibit estrogen receptors.
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PMC12730593
Because cancer remains one of the leading causes of mortality worldwide, identifying compounds that may complement chemotherapy is of great interest.
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PMC12730593
In this review, we summarize advances reported over the past decade regarding the antitumor properties of isoflavones, with emphasis on both in vitro and in vivo effects, as well as chemical, botanical, and pharmacological aspects.
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PMC12730593
A literature search was conducted using the PubMed database covering studies published from January 2014 to April 2025 using the following keywords: ‘isoflavones’ and ‘anticancer’, ‘antitumoral’, and ‘antiproliferative’ and ‘cytotoxicity’.
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PMC12730593
Genistein and daidzein emerge as the most extensively studied isoflavones, with well-documented anticancer activity.
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PMC12730593
Reported anticancer effects include induction of apoptosis, ROS generation, cell cycle arrest, inhibition of cell migration and invasion, loss of mitochondrial membrane potential, modulation of estrogen-related pathways, and antiangiogenic activity.
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PMC12730593
In addition to these mechanistic findings, several isoflavones demonstrated significant tumor growth inhibition in xenograft models, reinforcing their translational potential.
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