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Progesterone downregulation of miR-141 contributes to expansion of stem-like breast cancer cells through maintenance of progesterone receptor and Stat5a.

ABSTRACT: Progesterone (P4) has emerged as an important hormone-regulating mammary stem cell (MaSC) populations. In breast cancer, P4 and synthetic analogs increase the number of stem-like cells within luminal estrogen receptor (ER)- and progesterone receptor (PR)-positive breast cancers. These cells gain expression of de-differentiated cell markers CD44 and cytokeratin 5 (CK5), lose luminal markers ER and PR, and are more therapy resistant. We previously described that P4 downregulation of microRNA (miR)-29a contributes to the expansion of CD44(high) and CK5(+) cells. Here we investigated P4 downregulation of miR-141, a member of the miR-200 family of tumor suppressors, in facilitating an increase in stem-like breast cancer cells. miR-141 was the sole member of the miR-200 family P4-downregulated at the mature miRNA level in luminal breast cancer cell lines. Stable inhibition of miR-141 alone increased the CD44(high) population, and potentiated P4-mediated increases in both CD44(high) and CK5(+) cells. Loss of miR-141 enhanced both mammosphere formation and tumor initiation. miR-141 directly targeted both PR and signal transducer and activator of transcription 5A (Stat5a), transcription factors important for MaSC expansion. miR-141 depletion increased PR protein levels, even in cell lines where PR expression is estrogen dependent. Stat5a suppression via small interfering RNA or a small-molecule inhibitor reduced the P4-dependent increase in CK5(+) and CD44(high) cells. These data support a mechanism by which P4-triggered loss of miR-141 facilitates breast cancer cell de-differentiation through deregulation of PR and Stat5a, two transcription factors important for controlling mammary cell fate.

SUBMITTER: Finlay-Schultz J

PROVIDER: S-EPMC4369481 | biostudies-literature | 2015 Jul

REPOSITORIES: biostudies-literature

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Progesterone downregulation of miR-141 contributes to expansion of stem-like breast cancer cells through maintenance of progesterone receptor and Stat5a.

Finlay-Schultz J J Cittelly D M DM Hendricks P P Patel P P Kabos P P Jacobsen B M BM Richer J K JK Sartorius C A CA

Oncogene 20140922 28

Progesterone (P4) has emerged as an important hormone-regulating mammary stem cell (MaSC) populations. In breast cancer, P4 and synthetic analogs increase the number of stem-like cells within luminal estrogen receptor (ER)- and progesterone receptor (PR)-positive breast cancers. These cells gain expression of de-differentiated cell markers CD44 and cytokeratin 5 (CK5), lose luminal markers ER and PR, and are more therapy resistant. We previously described that P4 downregulation of microRNA (miR) ...[more]

PMID: 25241899

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Project description:Clinically, prostate cancer (PCa) exhibits a high avidity to metastasize to bone. miR-141-3p is an extensively studied miRNA in cancers and downregulation of miR-141-3p has been widely reported to be involved in the progression and metastasis of several human cancer types. However, the clinical significance and biological roles of miR-141-3p in bone metastasis of PCa are still unclear.miR-141-3p expression was examined in 89 non-bone metastatic and 52 bone metastatic PCa tissues by real-time PCR. Statistical analysis was performed to investigate the clinical correlation between miR-141-3p expression levels and clinicopathological characteristics in PCa patients. The biological roles of miR-141-3p in bone metastasis of PCa were evaluated both in vitro and a mouse intracardial model in vivo. Bioinformatics analysis, Western blot, luciferase reporter and miRNA immunoprecipitation assays were performed to explore and examine the relationship between miR-141-3p and its potential targets. Clinical correlation of miR-141-3p with its targets was examined in clinical PCa tissues.miR-141-3p expression is reduced in bone metastatic PCa tissues compared with non-bone metastatic PCa tissues. Low expression of miR-141-3p positively correlates with serum PSA levels, Gleason grade and bone metastasis status in PCa patients. Furthermore, upregulating miR-141-3p suppresses the EMT, invasion and migration of PCa cells in vitro. Conversely, silencing miR-141-3p yields an opposite effect. Importantly, upregulating miR-141-3p dramatically reduces bone metastasis of PC-3 cells in vivo. Our results further show that miR-141-3p inhibits the activation of NF-?B signaling via directly targeting tumor necrosis factor receptor-associated factor 5(TRAF5) and 6 (TRAF6), which further suppresses invasion, migration and bone metastasis of PCa cells. The clinical negative correlation of miR-141-3p expression with TRAF5, TRAF6 and NF-?B signaling activity is demonstrated in PCa tissues.Our findings unravel a novel mechanism underlying the bone metastasis of PCa, suggesting that miR-141-3p mimics might represent a potential therapeutic avenue for the treatment of PCa bone metastasis.

Project description:INTRODUCTION: Experimental and clinical evidence points to a critical role of progesterone and the nuclear progesterone receptor (PR) in controlling mammary gland tumorigenesis. However, the molecular mechanisms of progesterone action in breast cancer still remain elusive. On the other hand, micro RNAs (miRNAs) are short ribonucleic acids which have also been found to play a pivotal role in cancer pathogenesis. The role of miRNA in progestin-induced breast cancer is poorly explored. In this study we explored progestin modulation of miRNA expression in mammary tumorigenesis. METHODS: We performed a genome-wide study to explore progestin-mediated regulation of miRNA expression in breast cancer. miR-16 expression was studied by RT-qPCR in cancer cell lines with silenced PR, signal transducer and activator of transcription 3 (Stat3) or c-Myc, treated or not with progestins. Breast cancer cells were transfected with the precursor of miR-16 and proliferation assays, Western blots or in vivo experiments were performed. Target genes of miR-16 were searched through a bioinformatical approach, and the study was focused on cyclin E. Reporter gene assays were performed to confirm that cyclin E 3'UTR is a direct target of miR-16. RESULTS: We found that nine miRNAs were upregulated and seven were downregulated by progestin in mammary tumor cells. miR-16, whose function as a tumor suppressor in leukemia has already been shown, was identified as one of the downregulated miRNAs in murine and human breast cancer cells. Progestin induced a decrease in miR-16 levels via the classical PR and through a hierarchical interplay between Stat3 and the oncogenic transcription factor c-Myc. A search for miR-16 targets showed that the CCNE1 gene, encoding the cell cycle regulator cyclin E, contains conserved putative miR-16 target sites in its mRNA 3' UTR region. We found that, similar to the molecular mechanism underlying progestin-modulated miR-16 expression, Stat3 and c-Myc participated in the induction of cyclin E expression by progestin. Moreover, overexpression of miR-16 abrogated the ability of progestin to induce cyclin E upregulation, revealing that cyclin E is a novel target of miR-16 in breast cancer. Overexpression of miR-16 also inhibited progestin-induced breast tumor growth in vitro and in vivo, demonstrating for the first time, a role for miR-16 as a tumor suppressor in mammary tumorigenesis. We also found that the ErbB ligand heregulin (HRG) downregulated the expression of miR-16, which then participates in the proliferative activity of HRG in breast tumor cells. CONCLUSIONS: In this study, we reveal the first progestin-regulated miRNA expression profile and identify a novel role for miR-16 as a tumor suppressor in progestin- and growth factor-induced growth in breast cancer.

Dataset Information

Progesterone downregulation of miR-141 contributes to expansion of stem-like breast cancer cells through maintenance of progesterone receptor and Stat5a.

Publications

Progesterone downregulation of miR-141 contributes to expansion of stem-like breast cancer cells through maintenance of progesterone receptor and Stat5a.

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