ABSTRACT
AIMS: MicroRNAs (miRs) have been shown to play important roles in tumour progression. Their expression pattern can be useful for cancer classification. However, little is known about miRs in mammary phyllodes tumours (PT). METHODS AND RESULTS: In this study, polymerase chain reaction (PCR)-based miR profiling was performed in a small PT cohort to identify deregulated miRs in malignant PT. The purported roles and targets of these miRs were further validated. Unsupervised clustering of miR expression profiling segregated PT into different grades, implicating the miR profile in PT classification. Among the deregulated miRs, miR-21, miR-335 and miR-155 were validated to be higher in malignant than in lower-grade PT in the independent cohort by quantitative PCR (qPCR) (P ≤ 0.032). Their expression correlated with some of the malignant histological features, including high stromal cellularity, nuclear pleomorphism and mitosis. Subsequent analysis of their downstream proteins, namely PTEN for miR-21/miR-155 and Rb for miR-335, also showed an independent significant negative association between miR and protein expression. CONCLUSIONS: Differential expression of miRs in PT could be useful in diagnosis and grading of PT. Their deregulated expression, together with the altered downstream targets, implicated their active involvement in PT malignant transformation.
Subject(s)
Breast Neoplasms/genetics , Breast Neoplasms/pathology , MicroRNAs/genetics , Phyllodes Tumor/genetics , Phyllodes Tumor/pathology , RNA, Neoplasm/genetics , Biomarkers, Tumor/genetics , Biomarkers, Tumor/metabolism , Breast Neoplasms/metabolism , Female , Gene Expression Profiling , Gene Expression Regulation, Neoplastic , Genes, Retinoblastoma , Genes, p16 , Humans , MicroRNAs/metabolism , PTEN Phosphohydrolase/genetics , Phyllodes Tumor/metabolism , RNA, Neoplasm/metabolismABSTRACT
Oncogenic Ras mutations are rare in gastric cancer, indicating that other mechanisms may be responsible for aberrant Ras activation in this type of cancer. Ezrin is critical to Ras activation by remodeling cortical actin cy-toskeleton. In this study, we aimed to illustrate the relevance and regulation of ezrin in gastric cancer. Ezrin was upregulated in gastric cancer cells. Ezrin siRNA inhibited Ras activation, cell growth and cell migration. Ezrin overex-pression was correlated with a poor outcome of gastric cancer patients (n=150, p<0.01). Cox regression analysis revealed a significant value of ezrin expression in prognosis prediction of gastric cancer (relative risk: 2.37, 95% confidence interval: 1.24-4.56, p<0.01). MiR-204, which was predicted to target ezrin, was downregulated in gastric cancer cells and gastric carcinomas (n=22, p<0.01). MiR-204 inhibited ezrin expression, Ras activation, cell growth and cell migration. Importantly, miR-204 suppressed the expression of luciferase controlled by wild-type but not mutated ezrin 3'-UTR. In conclusion, ezrin is important to Ras activation in gastric cancer. Its upregulation is an independent prognosis prediction factor for gastric cancer. By contributing to ezrin upregulation, miR-204 downregulation represents a novel mechanism for aberrant Ras activation in gastric carcinogenesis.
