ABSTRACT
BACKGROUND: Ovarian cancer is the leading lethal, gynecological malignancy in the United States. No doubt, the continued morbidity and mortality of ovarian cancer reflects a poor understanding of invasive mechanisms. Recent studies reveal that ovarian cancers express aberrant microRNAs (miRNAs or miRs), some of which have oncogenic or tumor suppressor properties. Several studies suggested that miR-205 is involved in tumorigenesis. Presently, we investigate the molecular mechanisms and target of miR-205 in ovarian cancer. METHODS: Quantitative real-time polymerase chain reaction and western blot were performed to assess miR-205 and transcription factor 21 (TCF21) expression in ovarian cancer and normal ovary samples. The effect of miR-205 on TCF21 was determined by luciferase reporter assay and western blot. The effect of miR-205 and TCF21 on cell invasion was quantitated using transwell invasion assay. RESULT: miR-205 expression was increased in ovarian cancer and it promoted the invasive behavior of ovarian cancer cell lines (OVCAR-5, OVCAR-8 and SKOV-3). miR-205 directly targeted TCF21, which was significantly decreased in ovarian cancer tissue. miR-205 inhibited TCF21 expression and as a consequence blunted the inhibitory effect of TCF21 on cell invasion. Matrix Metalloproteinases (MMPs) play an important role in cancer invasion and metastasis. TCF21 inhibited MMP-2 and MMP-10 and decreased ovarian cancer cell invasion. Co-transfection of TCF21 expression plasmid with miR-205 mimic diminished the inhibitory effect of TCF21 on MMP-2 and MMP-10 in ovarian cancer cells. CONCLUSION: miR-205 appears to have an important role in the spread of ovarian cancer by targeting TCF21. These findings offer a new mechanism of ovarian cancer tumorigenesis, which could be useful for the development of new therapeutic approaches to ovarian cancer treatment.
Subject(s)
Basic Helix-Loop-Helix Transcription Factors/genetics , MicroRNAs/physiology , Ovarian Neoplasms/genetics , Basic Helix-Loop-Helix Transcription Factors/antagonists & inhibitors , Basic Helix-Loop-Helix Transcription Factors/metabolism , Cell Transformation, Neoplastic/genetics , Female , Gene Expression Regulation, Neoplastic , Humans , Matrix Metalloproteinases/physiology , MicroRNAs/genetics , Middle Aged , Neoplasm Invasiveness/genetics , Ovarian Neoplasms/metabolism , Ovarian Neoplasms/pathology , Ovary/metabolism , RNA, Neoplasm/genetics , RNA, Neoplasm/physiology , Tumor Cells, Cultured , Up-RegulationABSTRACT
PURPOSE: This study evaluated efficacy of single-agent trastuzumab against advanced or recurrent HER2-positive endometrial carcinoma (EC), and explored predictors for HER2 amplification. PATIENTS AND METHODS: Eligible patients had measurable stage III, IV, or recurrent EC. There was no limit on prior therapy although total prior doxorubicin dose was limited to 320 mg/m(2). Tumors were required to have HER2 overexpression (2+ or 3+ immunohistochemical staining) or HER2 amplification (FISH HER2/CEP 17 ratio >2.0). Trastuzumab was administered intravenously at a dose of 4 mg/kg in week 1, then 2 mg/kg weekly until disease progression. The primary endpoint was tumor response. RESULTS: Of the 286 tumors centrally screened by LabCorp, 33 (11.5%) were HER2-amplified. Three of 8 clear (38%) cell carcinomas and 7 of 25 serous carcinomas (28%) screened exhibited HER2 amplification compared with 7% (2/29) of endometrioid adenocarcinomas. HER2 overexpression was correlated with HER2 amplification (r=0.459; p<0.0001). Thirty-four women were enrolled; 1 was excluded (refused treatment); and 18 had tumors with known HER2 amplification. No major tumor responses were observed. Twelve women experienced stable disease, 18 had increasing disease, and 3 were indeterminate for tumor response. Neither HER2 overexpression nor HER2 amplification appeared to be associated with progression-free survival or overall survival. CONCLUSION: Trastuzumab as a single agent did not demonstrate activity against endometrial carcinomas with HER2 overexpression or HER2 amplification, although full planned accrual of women with HER2 amplified tumors was not achieved due to slow recruitment. Serous and clear cell endometrial carcinomas appear to be more likely to demonstrate HER2 amplification.
