Endometrial miR-181a and miR-98 expression is altered during transition from normal into cancerous state and target PGR, PGRMC1, CYP19A1, DDX3X, and TIMP3

Progesterone receptor membrane component 1 deficiency attenuates growth while promoting chemosensitivity of human endometrial xenograft tumors

Endometrial cancer is the leading gynecologic cancer in women in the United States with 52,630 women predicted to be diagnosed with the disease in 2014. The objective of this study was to determine if progesterone (P4) receptor membrane component 1 (PGRMC1) influenced endometrial cancer cell viability in response to chemotherapy in vitro and in vivo. A lentiviral-based shRNA knockdown approach was used to generate stable PGRMC1-intact and PGRMC1-deplete Ishikawa endometrial cancer cell lines that also lacked expression of the classical progesterone receptor (PGR). Progesterone treatment inhibited mitosis of PGRMC1-intact, but not PGRMC1-deplete cells, suggesting that PGRMC1 mediates the anti-mitotic actions of P4. To test the hypothesis that PGRMC1 attenuates chemotherapy-induced apoptosis, PGRMC1-intact and PGRMC1-deplete cells were treated in vitro with vehicle, P4 (1 µM), doxorubicin (Dox, 2 µg/ml), or P4 + Dox for 48 h. Doxorubicin treatment of PGRMC1-intact cells resulted in a significant increase in cell death; however, co-treatment with P4 significantly attenuated Dox-induced cell death. This response to P4 was lost in PGRMC1-deplete cells. To extend these observations in vivo, a xenograft model was employed where PGRMC1-intact and PGRMC1-deplete endometrial tumors were generated following subcutaneous and intraperitoneal inoculation of immunocompromised NOD/SCID and nude mice, respectively. Tumors derived from PGRMC1-deplete cells grew slower than tumors from PGRMC1-intact cells. Mice harboring endometrial tumors were then given three treatments of vehicle (1:1 cremophor EL: ethanol + 0.9% saline) or chemotherapy [Paclitaxel (15 mg/kg, i.p.) followed after an interval of 30 minutes by CARBOplatin (50 mg/kg)] at five day intervals. In response to chemotherapy, tumor volume decreased approximately four-fold more in PGRMC1-deplete tumors when compared with PGRMC1-intact control tumors, suggesting that PGRMC1 promotes tumor cell viability during chemotherapeutic stress. In sum, these in vitro and in vivo findings demonstrate that PGRMC1 plays a prominent role in the growth and chemoresistance of human endometrial tumors.

miR-98 suppresses melanoma metastasis through a negative feedback loop with its target gene IL-6

Dysregulated microRNA (miRNA) expression has a critical role in tumor development and metastasis. However, the mechanism by which miRNAs control melanoma metastasis is unknown. Here, we report reduced miR-98 expression in melanoma tissues with increasing tumor stage as well as metastasis; its expression is also negatively associated with melanoma patient survival. Furthermore, we demonstrate that miR-98 inhibits melanoma cell migration in vitro as well as metastatic tumor size in vivo. We also found that IL-6 is a target gene of miR-98, and IL-6 represses miR-98 levels via the Stat3-NF-κB-lin28B pathway. In an in vivo melanoma model, we demonstrate that miR-98 reduces melanoma metastasis and increases survival in part by reducing IL-6 levels; it also decreases Stat3 and p65 phosphorylation as well as lin28B mRNA levels. These results suggest that miR-98 inhibits melanoma metastasis in part through a novel miR-98-IL-6-negative feedback loop.

Hyaluronic acid promotes the expression of progesterone receptor membrane component 1 via epigenetic silencing of miR-139-5p in human and rat granulosa cells

Primary ovarian insufficiency (POI) is a serious reproductive dysfunction in which the follicle pool is reduced and depleted. Abnormal apoptosis of ovarian granulosa cells (GCs) is believed to result in follicle loss. Progesterone receptor membrane component 1 (PGRMC1), which is critical for GC survival, was reported to be reduced in POI patients, but the mechanism is unknown. In the present study, we found that PGRMC1 expression was correlated with the level of hyaluronic acid (HA) in POI patients. HA up-regulated PGRMC1 expression in GCs via suppression of miR-139-5p, which was proven by Western blotting and luciferase reporter assays to target PGRMC1. Consistent with these findings, levels of miR-139-5p were significantly increased and presented an inverse correlation with PGRMC1 in POI patients. Noticeably, HA inhibited CD44-mediated miR-139-5p expression but had no effect on luciferase activity after insertion of miR-139 promoter into luciferase plasmid. Interestingly, miR-139-5p was significantly up-regulated in KGN cells (GC tumor cell line) by the histone deacetylase inhibitor trichostatin A, indicating that HA down-regulated miR-139-5p expression via histone deacetylation. Taken together, we report an unrecognized mechanism of HA in the promotion of PGRMC1 expression, suggesting that HA may be a potential molecule for the prevention and treatment of POI.

Epigenetic regulation of Progesterone Receptor isoforms: from classical models to the sexual brain

Progesterone Receptor is a member of the nuclear receptor superfamily, which regulates several functions in both reproductive and non-reproductive tissues. Progesterone Receptor gene encodes for two main isoforms, A and B, and contains two specific promoters with their respective transcription start sites. The mRNA expression of both isoforms is mainly regulated by estrogens and specifically via the Estrogen Receptor Alpha, in a context specific manner. Furthermore, it has been reported in extensive physiological and pathological models that Progesterone Receptor isoforms regulation is related to the epigenetic state of their respective promoters. Epigenetic regulation of Progesterone Receptor isoforms in the brain is a recent and scarcely explored field in neurosciences. This review focuses on the epigenetic mechanisms involved in Progesterone Receptor regulation, emphasizing the implications for the sexual brain. Future directions for research about this important field are also discussed.

Celecoxib increases miR-222 while deterring aromatase-expressing breast tumor growth in mice

Background

Breast cancer is one of the most deadly diseases in women. Inhibiting the synthesis of estrogen is effective in treating patients with estrogen-responsive breast cancer. Previous studies have demonstrated that use of cyclooxygenase (COX) inhibitors is associated with reduced breast cancer risk.

Methods

In the present study, we employed an established mouse model for postmenopausal breast cancer to evaluate the potential mechanisms of the COX-2 inhibitor celecoxib. Aromatase-expressing MCF-7 cells were transplanted into ovariectomized athymic mice. The animals were given celecoxib at 1500 ppm or aspirin at 200 ppm by oral administration with androstenedione injection.

Results

Our results showed that both COX inhibitors could suppress the cancer xenograft growth without changing the plasma estrogen level. Protein expression of ERα, COX-2, Cyclin A, and Bcl-xL were reduced in celecoxib-treated tumor samples, whereas only Bcl-xL expression was suppressed in those treated with aspirin. Among the breast cancer-related miRNAs, miR-222 expression was elevated in samples treated with celecoxib. Further studies in culture cells verified that the increase in miR-222 expression might contribute to ERα downregulation but not the growth deterrence of cells.

Conclusion

Overall, this study suggested that both celecoxib and aspirin could prevent breast cancer growth by regulating proteins in the cell cycle and apoptosis without blocking estrogen synthesis. Besides, celecoxib might affect miR expression in an undesirable fashion.

Role of aromatase in sex-specific cerebrovascular endothelial function in mice

Stroke risk and outcome are strongly modified by estrogen. In addition to ovaries, estrogen is produced locally in peripheral tissue by the enzyme aromatase, and extragonadal synthesis becomes the major source of estrogen after menopause. Aromatase gene deletion in female mice exacerbates ischemic brain damage after stroke. However, it is not clear which cell type is responsible for this effect, since aromatase is expressed in multiple cell types, including cerebrovascular endothelium. We tested the hypothesis that cerebrovascular aromatase contributes to sex differences in cerebrovascular endothelial function. Cerebrocortical microvascular responses to the endothelium-dependent vasodilator ACh were compared between male and female wild-type (WT) and aromatase knockout (ArKO) mice by measuring laser-Doppler perfusion in vivo through a closed cranial window. Additional studies were performed in WT mice treated with the aromatase inhibitor fadrozole or vehicle. WT female mice had significantly greater responses to ACh compared with WT males (P < 0.001), which was associated with higher aromatase expression in female compared with male cerebral vessels (P < 0.05). ACh responses were significantly lower in ArKO compared with WT females (P < 0.05) and in WT females treated with fadrozole versus vehicle (P < 0.001). Conversely, ACh responses were significantly higher in ArKO versus WT males (P < 0.05). Levels of phosphorylated endothelial nitric oxide synthase (eNOS) were lower in ArKO versus WT female brains, but were not altered by aromatase deletion in males. We conclude that cerebrovascular endothelial aromatase plays an important and sexually dimorphic role in cerebrovascular function and that aromatase inhibitors in clinical use may have cardiovascular consequences in both males and females.

Deregulation of microRNA expression in thyroid neoplasias

MicroRNAs (miRNAs) have emerged as a class of powerful gene expression regulators. Acting at the post-transcriptional level, miRNAs modulate the expression of at least one-third of the mRNAs that are encoded by the human genome. The expression of a single gene can be regulated by several miRNAs, and every miRNA has more than one target gene. Thus, the miRNA regulatory circuit, which affects essential cellular functions, is of enormous complexity. Moreover, a fundamental role for miRNAs has been determined in the onset and progression of human cancers. Here, we summarize the main alterations in miRNA expression that have been identified in thyroid neoplasias and examine the mechanisms through which miRNA deregulation might promote thyroid cell transformation. We also discuss how the emerging knowledge on miRNA deregulation could be harnessed for the diagnosis and treatment of thyroid neoplasias.

MicroRNA-181a enhances the chemoresistance of human cervical squamous cell carcinoma to cisplatin by targeting PRKCD

MicroRNAs(miRNAs) are involved in regulating the response of cancer cells to various therapeutic interventions, but their involvement in the chemoresistance of human cervical squamous cell carcinoma is not fully understood. We found miR-181a was significantly up-regulated in specimens from patients with chemoresistant cervical squamous cell carcinoma. In this study, we aimed to clarify the role of miR-181a in regulating the chemoresistance of cervical cancer. Two human cervical squamous cancer cell lines, SiHa and Me180, were used. Enforced expression of miR-181a enhanced chemoresistance to cisplatin in cervical cancer cells through apoptosis reversion. In a nude mouse xenograft model, the overexpression of miR-181a markedly inhibited the therapeutic response to cisplatin. PRKCD, a target gene of miR-181a and a promoter of apoptosis, was negatively regulated by miR-181a. We found that the effect of miR-181a on chemoresistance was mediated by PRKCD. Additionally, silencing of PRKCD yielded an effect similar to that of miR-181a up-regulation and inhibited apoptosis in cervical cancer cells. Our findings suggest that miR-181a may function as an oncogene and induce chemoresistance in cervical squamous cell carcinoma cells at least in part by down-regulating PRKCD, thus may provide a biomarker for predicting chemosensitivity to cisplatin in patients with cervical squamous cancer.

MicroRNA miR-98 inhibits tumor angiogenesis and invasion by targeting activin receptor-like kinase-4 and matrix metalloproteinase-11

Angiogenesis and invasion are essential processes for solid tumor growth and dissemination. The tumor development process can be dependent on the activation of a series of signaling pathways, including growth factor-activated pathways. MicroRNAs have been shown to be critical for tumorigenesis, but their roles in cancer angiogenesis, invasion and other signaling pathways important for tumor development are still unclear in the context of tumor biology. We investigated the role of microRNA miR-98 in regulating tumor growth, invasion, and angiogenesis using a highly aggressive breast cancer model in vitro and in vitro. We found that the expression of miR-98 inhibited breast cancer cell proliferation, survival, tumor growth, invasion, and angiogenesis. Conversely, inhibition of endogenous miR-98 promoted cell proliferation, survival, tumor growth, invasion, and angiogenesis. It appeared that miR-98 inhibited angiogenesis by modulating endothelial cell activities including cell spreading, cell invasion and tubule formation. Interestingly, miR-98 reduced the expression of ALK4 and MMP11, both of which were potential targets of miR-98. Transfection of an anti-miR-98 construct increased the expression of both targets. We confirmed that mir-98 targeted the 3'-untranslated regions of ALK4 and MMP11. Finally, ALK4- and MMP11-specific siRNAs inhibited breast cancer cell proliferation, survival, and angiogenesis. Rescue experiments with ALK4 and MMP11 constructs reversed the anti-proliferative, anti-invasive and anti-angiogenic effects of miR-98. Our findings define a regulatory role of miR-98 in tumor angiogenesis and invasion through repressed ALK4 and MMP11 expression.

Role of microRNAs in the regulation of drug metabolism and disposition genes in diabetes and liver disease

INTRODUCTION

The pathogenesis of diabetes mellitus and nonalcoholic fatty liver disease (NAFLD) is complex, and the underlying molecular mechanisms are only partially understood.

AREAS COVERED

This review summarizes current knowledge of the role of microRNAs (miRNAs) in the regulation of drug absorption, distribution, metabolism, and excretion genes in the pathogenesis of diabetes and NAFLD. The literature search was performed using the PubMed database (up to February 2013).

EXPERT OPINION

miRNAs play a fundamental role in diabetes and NAFLD. This review focuses on the dysregulation of miRNAs involved in the regulation of drug metabolism and disposition in the pathogenesis of these metabolic syndromes. The evidence presented indicates that better understanding of the underlying molecular mechanisms associated with dysregulation of miRNAs controlling the cellular drug metabolizing system is of great importance not only from a scientific, but also from a clinical perspective. More importantly, an association between these metabolic disorders and miRNA dysregulation suggests that correcting miRNA expression by either their up-regulation or inhibition holds a promise for treating these metabolic syndrome and alleviating disease progression.

Promoter hypermethylation contributes to TIMP3 down-regulation in high stage endometrioid endometrial carcinomas

AIMS

Expression of tissue inhibitor of metalloproteinases-3 (TIMP-3) has been found to be decreased in several types of cancer by promoter gene hypermethylation. However, little is known regarding the silencing effect of TIMP3 promoter hypermethylation on gene and protein expression in endometrial carcinomas and its prognostic significance.

METHODS AND RESULTS

TIMP3 promoter hypermethylation and gene copy number variations were evaluated using a methylation-specific multiplex ligation-dependent probe amplification approach in 60 cases of endometrioid endometrial carcinomas. TIMP3 expression was also evaluated at the transcript and protein levels. Loss of TIMP-3 protein expression was found in 44 (73%) of 60 carcinomas. Promoter hypermethylation was identified in 25% (15 of 60); was more frequent in stages II-IV (55%, six of 11) than in stage I (18%, nine of 49; P = 0.021); and was found more commonly in tumours with deep myometrial invasion. MLH1 and TIMP3 promoters were hypermethylated simultaneously in the same group of tumours (P < 0.001). A correlation between TIMP3 methylation and microsatellite instability (MSI) was found (P = 0.005). TIMP3 copy number changes were frequently a loss (35%), whereas a gain was detected in only 5%.

CONCLUSIONS

TIMP3 promoter hypermethylation was associated with high stage endometrioid endometrial tumours with extrauterine spread. Nevertheless, promoter hypermethylation and loss of heterozygosity are not the only mechanisms for TIMP3 inactivation.

Plasminogen activator inhibitor 1 RNA-binding protein interacts with progesterone receptor membrane component 1 to regulate progesterone's ability to maintain the viability of spontaneously immortalized granulosa cells and rat granulosa cells

Progesterone receptor membrane component 1 (PGRMC1) mediates the antiapoptotic action of progesterone (P4). PGRMC1 interacts with plasminogen activator inhibitor 1 RNA-binding protein (PAIRBP1), but the functional significance of this interaction is unknown. To examine the function of PGRMC1-PAIRBP1 interaction, PAIRBP1 was depleted from spontaneously immortalized granulosa cells (SIGCs) and the effects on the expression and localization of PGRMC1 as well as P4's ability to bind to SIGCs and prevent apoptosis was assessed. Depleting PAIRBP1 enhanced cellular (3)H-P4 binding and did not alter the expression or cellular localization of PGRMC1 but attenuated P4's antiapoptotic action. Transfection of a PGRMC1-green fluorescent protein (GFP) peptide mimic, which binds PAIRBP1 as demonstrated by in situ proximity assay, doubled the rate at which SIGCs undergo apoptosis compared to cells transfected with either the empty GFP expression vector or Pairbp1 small interfering RNA. Moreover, P4 did not prevent these cells from undergoing apoptosis. Similar studies conducted with granulosa cells isolated from immature rats also showed that PGRMC1 interacts with PAIRBP1 and that transfection of PGRMC1-GFP peptide mimic accelerates the rate of granulosa cell apoptosis by 4-fold even in the presence of serum and P4. These studies support the concept that the interaction between PAIRBP1-PGRMC1 is an essential component of the mechanism through which P4 inhibits apoptosis. Surprisingly, PGRMC1-PAIRBP1 interaction is not required for P4 binding or the cellular localization of PGRMC1 but rather appears to couple PGRMC1 to downstream components of the P4-PGRMC1 signal transduction pathway.