�-Elemene Reverses Chemoresistance of Breast Cancer via Regulating MDR-Related MicroRNA Expression

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Background: Currently, exosomes that act as mediators of intercellular communication are being researched extensively. Our previous studies confirmed that these exosomes contain microRNAs (miRNAs) that could alter chemo-susceptibility, which is partly attributed to the successful intercellular transfer of multidrug resistance (MDR)-specific miRNAs. We also confirmed that β-elemene could influence MDR-related miRNA expression and regulate the expression of the target genes PTEN and Pgp, which may lead to the reversal of the chemoresistant breast cancer (BCA) cells. We are the first to report these findings, and we propose the following logical hypothesis: β-elemene can mediate MDR-related miRNA expression in cells, thereby affecting the exosome contents, reducing chemoresistance transmission via exosomes, and reversing the drug resistance of breast cancer cells. Methods: MTT-cytotoxic, miRNA microarray, real-time quantitative PCR, Dual Luciferase Activity Assay, and Western blot analysis were performed to investigate the impact of β-elemene on the expression of chemoresistance specific miRNA and PTEN as well as Pgp in chemoresistant BCA exosomes. Results: Drug resistance can be reversed by β-elemene related to exosomes. There were 104 differentially expressed miRNAs in the exosomes of two chemoresistant BCA cells: adriacin (Adr) - resistant MCF-7 cells (MCF-7/Adr) and docetaxel (Doc) - resistant MCF-7 cells (MCF-7/Doc) that underwent treatment. Of these, 31 miRNAs were correlated with the constant changes in the MDR. The expression of miR-34a and miR-452 can lead to changes in the characteristics of two chemoresistant BCA exosomes: MCF-7/Adr exosomes (A/exo) and MCF-7/Doc exosomes (D/exo). The PTEN expression affected by β-elemene was significantly increased, and the Pgp expression affected by β-elemene was significantly decreased in both cells and exosomes. β-elemene induced a significant increase in the apoptosis rate in both MCF-7/Doc and MCF-7/Adr cells. Conclusions: Drug resistance can be reversed by β-elemene, which can alter the expression of some MDR-related miRNAs, including PTEN and Pgp in MCF-7/Adr and MCF-7/Doc in cells. It can therefore affect the exosome contents and induce the reduction of resistance transmission via exosomes.

Section: β-Elemene Treatment Alters the Expression Of Pten And Pgp Prsupporting

confidence: 67%

Section: Introductionsupporting

confidence: 70%

Section: Introductionmentioning

confidence: 99%

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β-Elemene Reverses Chemoresistance of Breast Cancer Cells by Reducing Resistance Transmission via Exosomes

Zhang

Yao

et al. 2015

Self Cite

“…In addition, despite the great advances achieved in radiotherapy and cytotoxic drug development, long term cure rates by standard therapies are disappointing owing to disseminated disease at diagnosis and chemotherapeutic resistance [148]. Ectopic miRNAs are involved in various drug resistant mechanisms including EMT, CSC, apoptosis avoidance, androgen signaling and multiple drug resistance (MDR) transporters [78,149,150]. Additionally, miR-100 can influence the sensitivity of tumors to chemo-or radiation therapy, so a combination of miR-100 chemo-or radiation therapy proves to be a novel antitumor strategy.…”

Section: Mir-100 In Cancer Therapymentioning

confidence: 99%

Multiple Roles of MicroRNA-100 in Human Cancer and its Therapeutic Potential

Li¹,

Gao²,

Zhang³

et al. 2015

MicroRNAs (miRNAs) are a recently discovered class of endogenous, small (about 22 nucleotides) non-coding RNAs, which play important roles in cancer development and progression. Emerging evidence shows that microRNAs exert their regulatory effects by directly binding to the 3'- untranslated regions (UTRs) of their target genes. MicroRNA-100 (miR-100) is aberrantly expressed and functions in many human cancers by regulating multiple cell processes, such as cell cycle, proliferation, differentiation, migration, invasion and apoptosis, via post-transcriptionally regulating various target genes. A better understanding of the molecular mechanisms involved in miR-100-mediated tumor progression will provide an opportunity for exploring novel miR-100-based targeted therapies for human cancers. This review aims to summarize the recently published literature on the roles of miR-100 in regulating tumorigenesis, and explore its potential clinical applications for cancer diagnosis, prognosis and clinical treatment.

“…Thus, understanding of the mechanisms underlying the growth of BC is extremely important for its therapy [2][3][4][5].…”

Section: Introductionmentioning

confidence: 99%

Pttg1 Promotes Growth of Breast Cancer through P27 Nuclear Exclusion

Xiea

Wangb²

2016

Background/Aims: A role of Pituitary Tumor Transforming Gene 1 (Pttg1) in the carcinogenesis has been shown in some cancers, but not in BC (BC). Methods: We compared the levels of Pttg1 in the resected BC tissue with the adjacent normal breast tissue from the same patient. We modified Pttg1 levels in a BC cell line, MCF7, by either a Pttg1 transgene, or a Pttg1 shRNA. The cell growth was measured in an MTT assay. The cell apoptosis was measured by apoptosis assay. The nuclear protein of cell-cycle-related genes was examined in Pttg1-modifed BC cells. Co-immunoprecipitation was performed to examine the association of Pttg1 and p27. Results: We detected significantly higher levels of Pttg1 in the resected BC tissue, compared to the adjacent normal breast tissue from the same patient. Overexpression or depletion of Pttg1 in MCF7 significantly increased or inhibited cell growth, respectively. Changes in Pttg1 levels, however, did not alter cell apoptosis, suggesting that Pttg1 increases cell growth through augmented cell proliferation, rather than decreased cell apoptosis. Among all examined cell-cycle-related proteins in Pttg1-modifed BC cells, only nuclear p27 levels were significantly affected. Further, co-immunoprecipitation showed that Pttg1 directly associated with p27. Conclusion: Pttg1 may increase BC cell growth through nuclear exclusion of p27, which highlights a novel molecular regulatory machinery in tumorigenesis of BC.