Cancer Stem Cells

Mol Nutr Food Res.2013 Jul;57(7):1123-34. doi: 10.1002/mnfr.201200549. Epub 2013 Mar 15.

Pterostilbene, a bioactive component of blueberries, suppresses the generation of breast cancer stem cells within tumor microenvironment and metastasis via modulating NF-κB/microRNA 448 circuit.

Mak KK¹,Wu AT, Lee WH, Chang TC, Chiou JF, Wang LS, Wu CH, Huang CY, Shieh YS, Chao TY, Ho CT, Yen GC, Yeh CT.

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Abstract

SCOPE: Tumor-associated macrophages (TAMs) have been shown to promote metastasis and malignancy. Pterostilbene, a natural stilbene isolated from blueberries, has been suggested for anti-cancer effects. Here, we explored the potential cancer stem cells (CSCs)/TAM modulating effects of pterostilbene in breast cancer.

METHODS AND RESULTS: Using flowcytometric and Boyden chamber assay, we showed MCF7 and MDA-MB-231 cells cocultured with M2 TAMs exhibited increased percentage of CD44(+) /CD24(-) CSC population and migratory/invasive abilities. RT-PCR results showed that CD44(+) /CD24(-) cells expressed an increased level of HIF-1α, β-catenin, Twist1, and NF-κB and enhanced tumor sphere forming ability. Additionally, pterostilbene treatment dose dependently overcame M2 TAM-induced enrichment of CSCs and metastatic potential of breast cancer cells. Mechanistically, pterostilbene suppressed NFκB, Twist1, vimentin, and increased E-cadherin expression. Using siRNA technique, we demonstrated that pterostilbene-mediated NFκB downregulation was correlated to an increased amount of microRNA 448. Finally, pterostilbene-mediated suppression in tumorigenesis and metastasis was validated by noninvasive bioluminescence in mice bearing M2 TAM cocultured MDA-MB-231 tumor.

CONCLUSION: Pterostilbeneeffectively suppresses the generation of CSCs and metastatic potential under the influence of M2 TAMs via modulating EMT associated signaling pathways, specifically NF-κB/miR488 circuit. Thus, pterostilbene could be an ideal anti-CSC agent in clinical settings.

KEYWORDS: Breast cancer stem cells; Epithelial-to-mesenchymal transition; Pterostilbene; Tumor-associated macrophages; miR448

PMID: 23504987

Evid Based Complement Alternat Med.2013;2013:258425. doi: 10.1155/2013/258425. Epub 2013 Jun 26.

BlueBerry Isolate, Pterostilbene, Functions as a Potential Anticancer Stem Cell Agent in Suppressing Irradiation-Mediated Enrichment of Hepatoma Stem Cells.

Lee CM¹, Su YH, Huynh TT, Lee WH, Chiou JF, Lin YK, Hsiao M, Wu CH, Lin YF, Wu AT, Yeh CT.

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Abstract

For many malignancies, radiation therapy remains the second option only to surgery in terms of its curative potential. However, radiation-induced tumor cell death is limited by a number of factors, including the adverse response of the tumor microenvironment to the treatment and either intrinsic or acquired mechanisms of evasive resistance, and the existence of cancer stem cells (CSCs). In this study, we demonstrated that using different doses of irradiation led to the enrichment of CD133(+) Mahlavu cells using flow cytometric method. Subsequently, CD133(+) Mahlavu cells enriched by irradiation were characterized for their stemness gene expression, self-renewal, migration/invasion abilities, and radiation resistance. Having established irradiation-enriched CD133(+) Mahlavu cells with CSC properties, we evaluated a phytochemical, pterostilbene (PT), found abundantly in blueberries, against irradiation-enriched CSCs. It was shown that PT treatment dose-dependently reduced the enrichment of CD133(+) Mahlavu cells upon irradiation; PT treatment also prevented tumor sphere formation, reduced stemness gene expression, and suppressed invasion and migration abilities as well as increasing apoptosis of CD133(+) Mahlavu CSCs. Based on our experimental data, pterostilbene could be used to prevent the enrichment of CD133(+) hepatoma CSCs and should be considered for future clinical testing as a combined agent for HCC patients.

PMID: 23878592

J Agric Food Chem.2015 Mar 11;63(9):2432-41. doi: 10.1021/acs.jafc.5b00002. Epub 2015 Feb 25.

Targeting cancer stem cells in breast cancer: potential anticancer properties of 6-shogaol and pterostilbene.

Wu CH¹,Hong BH, Ho CT, Yen GC.

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Abstract

Breast cancer stem cells (BCSCs) constitute a small fraction of the primary tumor that can self-renew and become a drug-resistant cell population, thus limiting the treatment effects of chemotherapeutic drugs. The present study evaluated the cytotoxic effects of five phytochemicals including 6-gingerol (6-G), 6-shogaol (6-S), 5-hydroxy-3,6,7,8,3′,4′-hexamethoxyflavone (5-HF), nobiletin (NOL), and pterostilbene(PTE) on MCF-7 breast cancer cells and BCSCs. The results showed that 6-G, 6-S, and PTE selectively killed BCSCs and had high sensitivity for BCSCs isolated from MCF-7 cells that expressed the surface antigen CD44(+)/CD24(-). 6-S and PTE induced cell necrosis phenomena such as membrane injury and bleb formation in BCSCs and inhibited mammosphere formation. In addition, 6-S and PTE increased the sensitivity of isolated BCSCs to chemotherapeutic drugs and significantly increased the anticancer activity of paclitaxel. Analysis of the underlying mechanism showed that 6-S and PTE decreased the expression of the surface antigen CD44 on BCSCs and promoted β-catenin phosphorylation through the inhibition of hedgehog/Akt/GSK3β signaling, thus decreasing the protein expression of downstream c-Myc and cyclin D1 and reducing BCSC stemness.

KEYWORDS: 6-shogaol; breast cancer stem cells; hedgehog; mammospheres; pterostilbene

PMID: 25686711

J Nutr Biochem.2015 May;26(5):466-75. doi: 10.1016/j.jnutbio.2014.11.015. Epub 2015 Jan 19.

Pterostilbene suppressed irradiation-resistant glioma stem cells by modulating GRP78/miR-205 axis.

Huynh TT¹,Lin CM², Lee WH³, Wu AT⁴, Lin YK⁵, Lin YF⁶, Yeh CT⁷, Wang LS⁸.

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Abstract

Glioblastoma multiforme (GBM) is the most aggressive type characterized by relapse and resistance even with the combination of radio- and chemotherapy. The presence of glioma stem cells (GSCs) has been shown to contribute to tumorigenesis, recurrence and treatment resistance. Particularly, CD133-positive glioma cells have been shown to represent the subpopulation that confers glioma radioresistance and suggested to be the source of tumor recurrence after radiation. Thus, a better understanding and the development of agents which target GSCs could potentially lead to a significant improvement in treating GBM patients. Here, we demonstrated that GRP78 (an antistress protein) was highly expressed in GBM cells along with β-catenin and Notch and correlated to the development of GSCs. CD133+ GSCs exhibited enhanced migration/invasion and self-renewal abilities. When GRP78 was silenced, GSC properties were suppressed and the sensitivity towards irradiation increased. In addition, the level of microRNA 205 appeared to be negatively associated with GRP78 expression. Our previous study indicated that pterostilbene(PT) possessed anticancer stem cell properties in hepatocellular carcinoma. Thus, we examined whether PT is also effective against GSCs. We found that PT-treated GSCs exhibited suppressed self-renewal and irradiation-resistant abilities. PT-mediated effects were associated with an increase of miR-205. Finally, we showed that PT treatment suppressed tumorigenesis in GSC xenograft mice. In conclusion, we provided evidence that GRP78/miR-205 axis played an important role in GSC maintenance and irradiation resistance. PT treatment suppressed GSC development via negatively modulating GRP78 signaling. PT may be considered for combined therapeutic agent to enhance irradiation efficacy in GBM patients.

KEYWORDS: CD133+ glioma stem cells; Glucose-regulated protein, 78 kDa (GRP78); Irradiation resistance; Pterostilbene; miR-205

PMID: 25736407

Oncotarget.2016 Jun 28;7(26):39363-39375. doi: 10.18632/oncotarget.8101.

Modulation of macrophage polarization and lung cancer cell stemness by MUC1 and development of a related small-molecule inhibitor pterostilbene.

Huang WC^1,2,3,Chan ML^1,2,3, Chen MJ^3,4, Tsai TH^1,5, Chen YJ^1,6,3,7.

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Abstract

Tumor-associated macrophages (TAMs) polarized to the M2 phenotype play key roles in tumor progression in different cancer types, including lung cancer. MUC1 expression in various types of cancer is an indicator of poorer prognosis. Elevated MUC1 expression has been reported in inflammatory lung macrophages and is associated with lung cancer development. Here, we investigated the role of M2-polarized TAMs (M2-TAMs) in the generation of lung cancer stem cells (LCSCs) and tested pterostilbene, a small-molecule agent that modulates MUC1 expression in lung cancer cells, with the goal of subverting the microenvironment toward a favorable anti-tumor impact. We found that MUC1 was overexpressed in lung cancer patients, which was associated with poor survival rates. M2-TAMs and cancer cell lines were co-cultured in an experimental tumor microenvironment model. The expression levels of MUC1 and cancer stemness genes significantly increased in lung cancer cells in the presence of the M2-TAM cells. Intriguingly, pterostilbene dose-dependently suppressed self-renewal ability in M2-TAMs-co-cultured lung cancer cells, and this suppression was accompanied by downregulation of MUC1, NF-κB, CD133, β-catenin, and Sox2 expression. Moreover, MUC1-silenced M2-TAMs exhibited a significantly lower ability to promote LCSC generation and decreased levels of NF-κB, CD133, and Sox2. The results suggest that MUC1 plays an important role in TAM-induced LCSC progression. Pterostilbene may have therapeutic potential for modulating the unfavorable effects of TAMs in lung cancer progression.

KEYWORDS: Immune response; Immunity; Immunology and Microbiology Section; M2 polarization; MUC1; lung cancerstem cells (CSCs); pterostilbene; tumor-associated macrophages (TAMs)

PMID: 27276704