ABSTRACT
Endometrial carcinoma is one of the most common gynecological malignancies, but the molecular events involved in the development and progression of endometrial carcinoma remain unclear. Dicer1 and cancer stem cells play important roles in cell motility and survival. This study investigated the role of the let-7 family and Dicer1 in the stemness of endometrial carcinoma cells. We profiled Dicer1 expression in clinical samples and explored its relationship with stem cell-associated markers and clinical parameters. We showed that Dicer1 dysfunction leads to the enrichment of tumor stemness features and tumor aggression both in vitro and in vivo. We also identified the mechanism related to this potential tumor-predisposing phenotype: loss of Dicer1 induced abnormal expression of the let-7 family, which comprises well-known tumor suppressors, thus regulating stemness in endometrial carcinoma cells.
Subject(s)
DEAD-box RNA Helicases/physiology , Endometrial Neoplasms/pathology , Ribonuclease III/physiology , Adult , Aged , Animals , Cell Line, Tumor , Female , Humans , Hyaluronan Receptors/analysis , Mice , Mice, Inbred BALB C , MicroRNAs/physiology , Middle Aged , Neoplastic Stem Cells/chemistry , Neoplastic Stem Cells/physiology , Tumor Suppressor Proteins/physiologyABSTRACT
PURPOSE: To elucidate the role of tumor-associated macrophage (TAM) in the loss of ERα in endometrial cancer (EC) and the underlying mechanism. MATERIALS AND METHODS: Tissue microarrays and immunohistochemistry assays were performed using endometrial cancer tissue along with coculture, immunofluorescence, invasion assays and ChIP-qPCR using a human endometrial cancer cell line. RESULTS: Compared with normal tissue, an increased number of TAM was found in EC tissue (34.0 ± 2.6 vs. 8.3 ± 1.1, respectively; p < 0.001), which may downregulate ERα (27.4%, p < 0.05 for HEC-1A and 16.9%, p < 0.05 for Ishikawa) and promote EC cell invasion (1.8-fold, p < 0.001 for HEC-1A and 2.0-fold, p < 0.001 for Ishikawa). Furthermore, we found that TAM-derived CXCL8 mediated the loss of ERα and cancer invasion via HOXB13. HOXB13 was highly expressed in the ERα-negative subtype (r = -0.204, p = 0.002) and low expression of ESR1 was associated with a poor prognosis for EC patients (log-rank p < 0.05). CONCLUSION: TAM-secreted CXCL8 downregulated the ERα expression of EC cells via HOXB13, which may be associated with cancer invasion, metastasis and poor prognosis.
Subject(s)
Carcinoma, Endometrioid/metabolism , Endometrial Neoplasms/metabolism , Estrogen Receptor alpha/metabolism , Homeodomain Proteins/metabolism , Interleukin-8/metabolism , Macrophages/metabolism , Paracrine Communication , Tumor Microenvironment , Carcinoma, Endometrioid/genetics , Carcinoma, Endometrioid/mortality , Carcinoma, Endometrioid/pathology , Cell Line, Tumor , Cell Movement , Chromatin Immunoprecipitation , Coculture Techniques , Down-Regulation , Endometrial Neoplasms/genetics , Endometrial Neoplasms/mortality , Endometrial Neoplasms/pathology , Estrogen Receptor alpha/genetics , Female , Fluorescent Antibody Technique , Gene Expression Regulation, Neoplastic , Homeodomain Proteins/genetics , Humans , Interleukin-8/genetics , Kaplan-Meier Estimate , Middle Aged , Neoplasm Invasiveness , Neoplasm Metastasis , Prognosis , Reverse Transcriptase Polymerase Chain Reaction , Signal Transduction , Time Factors , Tissue Array AnalysisABSTRACT
The tumor suppressor p53 and the transcriptional repressor Enhancer of Zeste Homolog 2 (EZH2) have both been implicated in the regulation of epithelial-mesenchymal transition (EMT) and tumor metastasis via their impacts on microRNA expression. Here, we report that mutant p53 (mutp53) promotes EMT in endometrial carcinoma (EC) by disrupting p68-Drosha complex assembly. Overexpression of mutp53 has the opposite effect of wild-type p53 (WTp53), repressing miR-26a expression by reducing pri-miR-26a-1 processing in p53-null EC cells. Re-expression of miR-26a in mutp53 EC cells decreases cell invasion and promotes mesenchymal-epithelial transition (MET). Rescuing miR-26a expression also inhibits EZH2, N-cadherin, Vimentin, and Snail expression and induces E-cadherin expression both in vitro and in vivo. Moreover, patients with higher serum miR-26a levels have a better survival rate. These results suggest that p53 gain-of-function mutations accelerate EC tumor progression and metastasis by interfering with Drosha and p68 binding and pri-miR-26a-1 processing, resulting in reduced miR-26a expression and EZH2 overexpression.
Subject(s)
Carcinoma/enzymology , Carcinoma/genetics , DEAD-box RNA Helicases/metabolism , Endometrial Neoplasms/enzymology , Endometrial Neoplasms/genetics , Epithelial-Mesenchymal Transition , MicroRNAs/genetics , Mutation , Polycomb Repressive Complex 2/metabolism , Ribonuclease III/metabolism , Tumor Suppressor Protein p53/genetics , Adult , Aged , Aged, 80 and over , Animals , Carcinoma/blood , Carcinoma/secondary , Cell Line, Tumor , Cell Movement , DEAD-box RNA Helicases/genetics , Disease Progression , Endometrial Neoplasms/blood , Endometrial Neoplasms/pathology , Enhancer of Zeste Homolog 2 Protein , Female , Gene Expression Regulation, Enzymologic , Gene Expression Regulation, Neoplastic , Humans , Mice, Nude , MicroRNAs/blood , Middle Aged , Neoplasm Invasiveness , Polycomb Repressive Complex 2/genetics , RNA Processing, Post-Transcriptional , Ribonuclease III/genetics , Signal Transduction , Time Factors , Transfection , Tumor Suppressor Protein p53/metabolismABSTRACT
Piwil1, a member of the Piwi family, has been well demonstrated to mediate tumorigenesis associated with DNA hypermethylation. It has been reported that Piwil1 is overexpressed in various types of cancer, including endometrial cancer. However, the underlying mechanism of Piwil1 in endometrial cancer remains largely unclear. PTEN exerts an important tumor suppressor role in endometrial carcinogenesis. The present study aimed to investigate whether Piwil1 could regulate the expression of PTEN. Herein, we found that Piwil1 could promote the loss of PTEN expression and increase aberrant hypermethylation of PTEN gene promoter in Ishikawa cells. We also found that Piwil1 could regulate the expression of DNA methyltransferase 1 (DNMT1). Silencing DNMT1 gene could upregulate the PTEN gene expression and change the methylation status of PTEN gene promoter in Ishikawa cells. These results suggested that Piwil1 caused the loss of PTEN expression through DNMT1-mediated PTEN hypermethylation. Taken together, these data provide a novel regulatory mechanism of Piwil1 in endometrial cancer.
