Metabolic Profiling of Dietary Polyphenols and Methylxanthines in Normal and Malignant Mammary Tissues from Breast Cancer Patients

Abstract

Scope: Dietary polyphenols may protect against breast cancer. However, it is unknown whether polyphenols reach human malignant breast tumors in molecular forms and(or) at concentrations likely to act against cancer. Methods and Results: Ninteen breast cancer patients consumed three capsules daily from biopsy-confirmed diagnosis to surgery (6 ± 2 days). The capsules contained pomegranate, orange, lemon, olive, cocoa, and grapeseed extracts plus resveratrol, providing 37 different phenolics (473.7 mg), theobromine and caffeine (19.7 mg). A total of 101 metabolites are identified in urine, 69 in plasma, 39 in normal (NT), and 33 in malignant (MT) tissues by UPLC-ESI-QTOF-MS. Eight control patients did not consume extracts. Phenolic-derived metabolites in MT and NT are mainly glucuronidated and(or) sulfated. Some representative metabolites detected in MT (median and range, pmol g −1 ) are urolithin-A-3-O-glucuronide (26.2; 3.2−66.5), 2,5-dihydroxybenzoic acid (40. 2; 27.7−52.2), resveratrol-3-O-sulfate (86.4; 7.8−224.4), dihydroresveratrol-3-O-glucuronide (109.9; 10.3−229.4), and theobromine (715.0; 153.9−3,216). Metabolites, as detected in breast tissues, do not exert antiproliferative or estrogenic/antiestrogenic activities in MCF-7 breast cancer cells. Conclusion: This is the first study that describes the metabolic profiling of dietary phenolics and methylxanthines in MT and NT comprehensively. Although phase-II conjugation might hamper a direct anticancer activity, long-term tumor-senescent chemoprevention cannot be discarded.

Conjugated Physiological Resveratrol Metabolites Induce Senescence in Breast Cancer Cells: Role of p53/p21 and p16/Rb Pathways, and ABC Transporters

“…Remarkably, the lack of senescence induction after the treatment with a mixture of RSV metabolites, representative of what is found in malignant mammary tissues, also suggested a potential competition of RSV metabolites for ABC transporters, where each metabolite could present different affinity to these ABC transporters. This fact is essential in the context of among many mechanisms mediating BC resistance, being one of the most studied is the overexpression of efflux ABC transporter proteins that mediates drug resistance .…”

“…[4,11,31] Regarding BC, a recent clinical trial reported the occurrence of RSV-derived metabolites, mainly glucuronidated and(or) sulfated, but not free RSV in both malignant and normal mammary tissues from breast cancer patients who consumed a mixture of dietary polyphenols including RSV. [11] These recently published results support the hypothesis that invokes the RSV metabolites as the putative molecules responsible for the possible in vivo biological effects of RSV against BC. However, another study showed that the conjugation of phenolic metabolites (including those for RSV) prevented short-term in vitro antiproliferative (72 h) or estrogenic/anti-estrogenic activities in BC cells after 3 days of treatment.…”

“…The deconjugation hypothesis has been described in vivo, under specific pro-inflammatory conditions, for several compounds including quercetin, luteolin, and urolithin A, and has been previously suggested to explain the in vivo effect of phenolic compounds and derived metabolites despite their low bioavailability. [45][46][47] Remarkably, the lack of senescence induction after the treatment with a mixture of RSV metabolites, representative of what is found in malignant mammary tissues, [11] also suggested a potential competition of RSV metabolites for ABC transporters, where each metabolite could present different affinity to these ABC transporters. This fact is essential in the context of among many mechanisms mediating BC resistance, being one of the most studied is the overexpression of efflux ABC transporter proteins that mediates drug resistance.…”

“…All the compounds were solubilized in DMSO (<0.5% in the culture medium) and filter sterilized (0.22 µm). Cells were exposed to 0.5, 1, and 10 µmol L −1 of RSV and RSV‐derived metabolites individually as well as to a mixture of metabolites as found in MT from BC patients . In addition, a representative mixture of RSV metabolites mimicking the situation in vivo (1.2 µmol L −1 RSV 3‐glur + 4.6 µmol L −1 DH‐RSV 3‐glur + 3.8 µmol L −1 RSV 3‐sulf + 0.4 µmol L −1 RSV 4´‐sulf = final concentration of 10 µmol L −1 ) were assayed to evaluate a possible synergistic, additive, or antagonistic effect.…”

“…Animal and human studies have demonstrated low bioavailability and rapid clearance of RSV from the circulation, which is related to its extensive phase‐II metabolism catalyzed by enzymes known as transferases, mainly UDP glucuronyl transferases and sulfotransferases (EC number 2.4.1.17 and 2.8.2, respectively), as well as to its microbiota‐derived metabolite dihydroresveratrol (DH‐RSV) . A recent clinical trial has reported RSV accumulation, mainly as sulfates and glucuronides, in normal and malignant human breast tissues similar to those reported in normal breast tissues for other phenolics such as isoflavones and prenylflavonoids …”