Gallotannin from Bouea macrophylla Seed Extract Suppresses Cancer Stem-like Cells and Radiosensitizes Head and Neck Cancer.

Cancer stem cells (CSCs) play a critical role in radiation resistance and recurrence. Thus, drugs targeting CSCs can be combined with radiotherapy to improve its antitumor efficacy. Here, we investigated whether a gallotannin extract from Bouea macrophylla seed (MPSE) and its main bioactive compound, pentagalloyl glucose (PGG), could suppress the stemness trait and further confer the radiosensitivity of head and neck squamous cell carcinoma (HNSCC) cell lines. In this study, we evaluate the effect of MPSE or PGG to suppress CSC-like phenotypes and radiosensitization of HNSCC cell lines using a series of in vitro experiments, tumorsphere formation assay, colony formation assay, apoptosis assay, and Western blotting analysis. We demonstrate that MPSE or PGG is able to suppress tumorsphere formation and decrease protein expression of cancer stem cell markers. MPSE or PGG also enhanced the radiosensitivity in HNSCC cells. Pretreatment of cells with MPSE or PGG increased IR-induced DNA damage (γ-H2Ax) and enhanced radiation-induced cell death. Notably, we observed that pretreatment with MPSE or PGG attenuated the IR-induced stemness-like properties characterized by tumorsphere formation and the CD44 CSC marker. Our findings describe a novel strategy for increasing therapeutic efficacy for head and neck cancer patients using the natural products MPSE and PGG.

A radiosensitizer, gallotannin-rich extract from Bouea macrophylla seeds, inhibits radiation-induced epithelial-mesenchymal transition in breast cancer cells.

BACKGROUND: Radioresistance can pose a significant obstacle to the effective treatment of breast cancers. Epithelial-mesenchymal transition (EMT) is a critical step in the acquisition of stem cell traits and radioresistance. Here, we investigated whether Maprang seed extract (MPSE), a gallotannin-rich extract of seed from Bouea macrophylla Griffith, could inhibit the radiation-induced EMT process and enhance the radiosensitivity of breast cancer cells. METHODS: Breast cancer cells were pre-treated with MPSE before irradiation (IR), the radiosensitizing activity of MPSE was assessed using the colony formation assay. Radiation-induced EMT and stemness phenotype were identified using breast cancer stem cells (CSCs) marker (CD24-/low/CD44+) and mammosphere formation assay. Cell motility was determined via the wound healing assay and transwell migration. Radiation-induced cell death was assessed via the apoptosis assay and SA-ß-galactosidase staining for cellular senescence. CSCs- and EMT-related genes were confirmed by real-time PCR (qPCR) and Western blotting. RESULTS: Pre-treated with MPSE before irradiation could reduce the clonogenic activity and enhance radiosensitivity of breast cancer cell lines with sensitization enhancement ratios (SERs) of 2.33 and 1.35 for MCF7 and MDA-MB231cells, respectively. Pretreatment of breast cancer cells followed by IR resulted in an increased level of DNA damage maker (γ-H2A histone family member) and enhanced radiation-induced cell death. Irradiation induced EMT process, which displayed a significant EMT phenotype with a down-regulated epithelial marker E-cadherin and up-regulated mesenchymal marker vimentin in comparison with untreated breast cancer cells. Notably, we observed that pretreatment with MPSE attenuated the radiation-induced EMT process and decrease some stemness-like properties characterized by mammosphere formation and the CSC marker. Furthermore, pretreatment with MPSE attenuated the radiation-induced activation of the pro-survival pathway by decrease the expression of phosphorylation of ERK and AKT and sensitized breast cancer cells to radiation. CONCLUSION: MPSE enhanced the radiosensitivity of breast cancer cells by enhancing IR-induced DNA damage and cell death, and attenuating the IR-induced EMT process and stemness phenotype via targeting survival pathways PI3K/AKT and MAPK in irradiated breast cancer cells. Our findings describe a novel strategy for increasing the efficacy of radiotherapy for breast cancer patients using a safer and low-cost natural product, MPSE.

Pentagalloyl Glucose- and Ethyl Gallate-Rich Extract from Maprang Seeds Induce Apoptosis in MCF-7 Breast Cancer Cells through Mitochondria-Mediated Pathway.

Bouea macrophylla Griffith, locally known as maprang, has important economic value as a Thai fruit tree. The maprang seed extract (MPSE) has been shown to exhibit antibacterial and anticancer activities. However, the bioactive constituents in MPSE and the molecular mechanisms underlying these anticancer activities remain poorly understood. This study aims to identify the active compounds in MPSE and to investigate the mechanisms involved in MPSE-induced apoptosis in MCF-7 treated cancer cells. The cytotoxic effect was determined by MTT assay. The apoptosis induction of MPSE was evaluated in terms of ROS production, mitochondrial membrane potential depolarization, and apoptosis-related gene expression. The compounds identified by HPLC and LC/MS analysis were pentagalloyl glucose, ethyl gallate, and gallic acid. MPSE treatment decreased cell proliferation in MCF-7 cells, and MPSE was postulated to induce G2/M phase cell cycle arrest. MPSE was found to promote intracellular ROS production in MCF-7 treated cells and to also influence the depolarization of mitochondrial membrane potential. In addition, MPSE treatment can lead to increase in the Bax/Bcl-2 gene expression ratio, suggesting that MPSE-induced apoptosis is mitochondria-dependent pathway. Our results suggest that natural products obtained from maprang seeds have the potential to target the apoptosis pathway in breast cancer treatments.

Maprang "Bouea macrophylla Griffith" seeds: proximate composition, HPLC fingerprint, and antioxidation, anticancer and antimicrobial properties of ethanolic seed extracts.

In this study, the Maprang (Bouea macrophylla Griffith) seeds of 3 Thai varieties of this plant were studied in terms of nutrition, phytochemicals, chemical antioxidants and the bioactivity of their extracts. Maprang seeds revealed high levels of carbohydrates, dietary fiber, energy, potassium, phosphorus, magnesium, and calcium. The Maprang seed extracts possessed a high polyphenolic content and exhibited antioxidant properties against DPPH˙, ABTS˙+, and ferric reduction. Additionally, 18-compounds were charaterized by RP-HPLC-DAD with two being recognized as gallic acid and ellagic acid and 16-unknown gallotannins. The HPLC fingerprint was composed of 4 major compounds. The extract showed active growth inhibition against leukemia, lung cancer cell lines and for 15 strains of bacteria. It is known to be particularly effective in drug resistant cells. Our results indicated that maprang seeds are a new natural source of nutrition, minerals and phytochemicals that may be applicable for use as a food supplement and as an effective drug in the treatment of certain diseases.