ABSTRACT
We identified a discrete number of microRNAs differentially expressed in benign or malignant mesothelial tissues. We focused on mir-145 whose levels were significantly downregulated in malignant mesothelial tissues and malignant pleural mesothelioma (MPM) cell lines as compared to benign tissues (pleura, peritoneum or cysts). We show that promoter hyper-methylation caused very low levels in MPM cell lines and specimens. Treatment of MPM cell lines with mir-145 agonists negatively modulated some protumorigenic properties of MPM cells, such as clonogenicity, cell migration and resistance to pemetrexed treatment. The main effector mechanism of the clonogenic death induced by mir-145 was that of accelerated senescence. We found that mir-145 targeted OCT4 via specific binding to its 3'-UTR. Increased intracellular levels of mir-145 decreased the levels of OCT4 and its target gene ZEB1, thereby counteracting the increase of OCT4 induced by pemetrexed treatment which is known to favor the development of chemoresistant cells. In line with this, reintroduction of OCT4 into mimic-145 treated cells counteracted the effects on clonogenicity and replicative senescence. This further supports the relevance of the mir-145-OCT4 interaction for the survival of MPM cells. The potential use of mir-145 expression levels to classify benign vs malignant mesothelial tissues and the differences between pemetrexed-induced senescence and that induced by the re-expression of mir-145 are discussed.
Subject(s)
Gene Expression Profiling , Gene Expression Regulation, Neoplastic , Lung Neoplasms/genetics , Mesothelioma/genetics , MicroRNAs/genetics , Pleural Neoplasms/genetics , 3' Untranslated Regions/genetics , Animals , Antineoplastic Agents/pharmacology , Base Sequence , Cell Line , Cell Line, Tumor , Cell Movement/genetics , Cell Survival/drug effects , Cell Survival/genetics , Cellular Senescence/genetics , DNA Methylation , Down-Regulation , Gene Knockdown Techniques , Glutamates/pharmacology , Guanine/analogs & derivatives , Guanine/pharmacology , HEK293 Cells , Humans , Lung Neoplasms/metabolism , Lung Neoplasms/pathology , Male , Mesothelioma/metabolism , Mesothelioma/pathology , Mesothelioma, Malignant , Mice, SCID , Octamer Transcription Factor-3/genetics , Octamer Transcription Factor-3/metabolism , Pemetrexed , Pleural Neoplasms/metabolism , Pleural Neoplasms/pathology , Reverse Transcriptase Polymerase Chain Reaction , Sequence Homology, Nucleic AcidABSTRACT
BACKGROUND: TP53 mutation is associated with decreased survival rate in head and neck squamous cell carcinoma (HNSCC) patients. We set out to identify microRNAs (miRNAs) whose expression associates with TP53 mutation and survival in HNSCC. PATIENTS AND METHODS: We analyzed TP53 status by direct sequencing of exons 2 through 11 of a prospective series of 121 HNSCC samples and assessed its association with outcome in 109 followed-up patients. We carried out miRNA expression profiling on 121 HNSCC samples and 66 normal counterparts. miRNA associations with TP53 mutations and outcome were evaluated. RESULTS: A TP53 mutation was present in 58% of the tumors and TP53 mutations were significantly associated with a shorter recurrence-free survival. This association was stronger in the clinical subgroup of patients subjected to adjuvant therapy after surgery. The expression of 49 miRNAs was significantly associated with TP53 status. Among these 49, we identified a group of 12 miRNAs whose expression correlates with recurrence-free survival and a group of 4 miRNAs that correlates with cancer-specific survival. The two groups share three miRNAs. Importantly, miRNAs that correlate with survival are independent prognostic factors either when considered individually or as signatures. CONCLUSIONS: miRNAs expression associates with TP53 status and with reduced survival after surgical treatment of squamous cell carcinoma of the head and neck.