Caveolin-1 mediates tumor cell migration and invasion and its regulation by miR-133a in head and neck squamous cell carcinoma

MicroRNAs (miRNAs) are small non-coding RNAs of approximately 22 nucleotides that can function as oncogenes or tumor suppressors in human cancer. Down-regulation of the miRNA miR-133a in many type of cancers, and a reduction of cell proliferation, migration, and invasion upon over-expression, suggests that miR-133a is a tumor suppressor. In this study, genome-wide gene expression analysis of HNSCC cells that over-express miR-133a showed that caveolin-1 (CAV1), a multifunctional scaffolding protein, is down-regulated, a result that was confirmed by real-time PCR and Western blot analysis. A luciferase reporter assay revealed that miR-133a is directly bound to CAV1 mRNA. Cancer cell migration and invasion were significantly inhibited in HNSCC cells transfected with si-CAV1. Therefore, CAV1 functions as an oncogene in HNSCC. The identification of tumor suppressive miRNAs and their target genes could provide new insights into potential mechanism of HNSCC carcinogenesis.     

The construction of an EST database for Bombyx mori and its application

To build a foundation for the complete genome analysis of Bombyx mori, we have constructed an EST database. Because gene expression patterns deeply depend on tissues as well as developmental stages, we analyzed many cDNA libraries prepared from various tissues and different developmental stages to cover the entire set of Bombyx genes. So far, the Bombyx EST database contains 35,000 ESTs from 36 cDNA libraries, which are grouped into approximately 11,000 nonredundant ESTs with the average length of 1.25 kb. The comparison with FlyBase suggests that the present EST database, SilkBase, covers >55% of all genes of Bombyx. The fraction of library-specific ESTs in each cDNA library indicates that we have not yet reached saturation, showing the validity of our strategy for constructing an EST database to cover all genes. To tackle the coming saturation problem, we have checked two methods, subtraction and normalization, to increase coverage and decrease the number of housekeeping genes, resulting in a 5-11% increase of library-specific ESTs. The identification of a number of genes and comprehensive cloning of gene families have already emerged from the SilkBase search. Direct links of SilkBase with FlyBase and WormBase provide ready identification of candidate Lepidoptera-specific genes.     

Tumour suppressors miR-1 and miR-133a target the oncogenic function of purine nucleoside phosphorylase (PNP) in prostate cancer

Background:

Our recent analyses of miRNA expression signatures showed that miR-1 and miR-133a were significantly reduced in several types of cancer. Interestingly, miR-1 and miR-133a are located on the same chromosomal locus in the human genome. We examined the functional significance of miR-1 and miR-133a in prostate cancer (PCa) cells and identified the novel molecular targets regulated by both miR-1 and miR-133a.

Methods and Results:

The expression levels of miR-1 and miR-133a were significantly downregulated in PCa compared with non-PCa tissues. Restoration of miR-1 or miR-133a in PC3 and DU145 cells revealed significant inhibition of proliferation, migration, and invasion. Molecular target identification by genome-wide gene expression analysis and luciferase reporter assay showed that purine nucleoside phosphorylase (PNP) was directly regulated by both miRNAs. Silencing of the PNP gene inhibited proliferation, migration, and invasion in both PC3 and DU145 cells. Immunohistochemistry detected positive staining of PNP in PCa specimens.

Conclusions:

Downregulation of miR-1 and miR-133a was a frequent event in PCa and both function as tumour suppressors. The PNP is a novel target gene of both miRNAs and potentially functions as an oncogene. Therefore, identification of novel molecular networks regulated by miRNAs may provide new insights into the underlying causes of PCa oncogenesis.     

miR-1 as a tumor suppressive microRNA targeting TAGLN2 in head and neck squamous cell carcinoma

Based on the microRNA (miRNA) expression signatures of hypopharyngeal and esophageal squamous cell carcinoma, we found that miR-1 was significantly down-regulated in cancer cells. In this study, we investigated the functional significance of miR-1 in head and neck squamous cell carcinoma (HNSCC) cells and identified miR-1-regulated novel cancer pathways. Gain-of-function studies using miR-1 revealed significant decreases in HNSCC cell proliferation, invasion, and migration. In addition, the promotion of cell apoptosis and cell cycle arrest was demonstrated following miR-1e transfection of cancer cells. A search for the targets of miR-1 revealed that transgelin 2 (TAGLN2) was directly regulated by miR-1. Silencing of TAGLN2 significantly inhibited cell proliferation and invasion in HNSCC cells. Down-regulation of miR-1 and up-regulation of TAGLN2 were confirmed in HNSCC clinical specimens. Our data indicate that TAGLN2 may have an oncogenic function and may be regulated by miR-1, a tumor suppressive miRNA in HNSCC. The identification of novel miR-1-regulated cancer pathways could provide new insights into potential molecular mechanisms of HNSCC carcinogenesis.     

Tumor suppressive microRNA‑138 contributes to cell migration and invasion through its targeting of vimentin in renal cell carcinoma

Many studies have recently suggested that microRNAs (miRNAs) contribute to the development of various types of human cancers as well as to their invasive and metastatic capacities. Previously, our miRNA expression signature of renal cell carcinoma (RCC) revealed that microRNA?138 (miR?138) was significantly reduced in cancer cells. The aim of the present study was to investigate the functional significance of miR?138 and to identify its target genes in RCC cells. Restoration of mature miR?138 in two RCC cell lines (A498 and 786?O) caused changes in the bleb-like cell morphology, characteristics of the epithelial-mesenchymal transition (EMT). Restoration also significantly inhibited migration and invasion in the two RCC cell lines, suggesting that miR?138 functions as a tumor suppressor. Genome-wide gene expression analysis (miR?138 transfectants and RCC clinical specimens) and TargetScan database studies showed that vimentin (VIM) is a promising candidate target gene of miR?138. It is well known that VIM is one of the most widely expressed mammalian intermediate filament proteins. Recent studies showed that VIM functions in cell adhesion, migration, survival and cell signaling processes via dynamic assembly/disassembly in cancer cells. We focused on VIM and investigated whether VIM was regulated by tumor suppressive miR?138 and contributed to cancer cell migration and invasion in RCC cells. Restoration of miR?138 in RCC cell lines suppressed VIM expression at both the mRNA and protein levels. Silencing studies of VIM in RCC cell lines demonstrated significant inhibition of cell migration and invasion activities in si-VIM transfectants. In clinical specimens of RCC, the expression levels of VIM were significantly upregulated in cancer tissues compared to adjacent non-cancerous tissues. Furthermore, immunohistochemistry showed that VIM expression levels in RCC specimens were significantly higher than those in normal renal tissues. These data suggest that VIM may function as an oncogene and is regulated by tumor suppressive miR?138. The existence of a tumor suppressive miR?138-mediated oncogenic pathway provides new insights into the potential mechanisms of RCC oncogenesis and metastasis.     

Replisome genes regulation by antitumor miR‐101‐5p in clear cell renal cell carcinoma

Analysis of microRNA (miRNA) regulatory networks is useful for exploring novel biomarkers and therapeutic targets in cancer cells. The Cancer Genome Atlas dataset shows that low expression of both strands of pre‐miR‐101 (miR‐101‐5p and miR‐101‐3p) significantly predicted poor prognosis in clear cell renal cell carcinoma (ccRCC). The functional significance of miR‐101‐5p in cancer cells is poorly understood. Here, we focused on miR‐101‐5p to investigate the antitumor function and its regulatory networks in ccRCC cells. Ectopic expression of mature miRNAs or siRNAs was investigated in cancer cell lines to characterize cell function, ie, proliferation, apoptosis, migration, and invasion. Genome‐wide gene expression and in silico database analyses were undertaken to predict miRNA regulatory networks. Expression of miR‐101‐5p caused cell cycle arrest and apoptosis in ccRCC cells. Downstream neighbor of son (DONSON) was directly regulated by miR‐101‐5p, and its aberrant expression was significantly associated with shorter survival in propensity score‐matched analysis (P = .0001). Knockdown of DONSON attenuated ccRCC cell aggressiveness. Several replisome genes controlled by DONSON and their expression were closely associated with ccRCC pathogenesis. The antitumor miR‐101‐5p/DONSON axis and its modulated replisome genes might be a novel diagnostic and therapeutic target for ccRCC.     

Risk analysis for depression and patient prognosis after open heart surgery.

BACKGROUND: The aim of the present study was to determine the predictors of depression as a complication after open heart surgery and influence of depression on the patients' prognosis. METHODS AND RESULTS: During the last 3 years, 97 patients (21.5%) of the 452 adult patients who had open heart surgery at our institute experienced depression after the operation. Patients who scored over 16 points using a Center for Epidemiological Studies Depression Scale were diagnosed with significant symptoms of depression. Depressed patients (group I, n=97) and non-depressed patients (group II, n=355) in terms of mortality and length of hospital stay were compared. Predictors for depression were identified by logistic regression analysis. The postoperative hospital stay was significantly longer in group I. Hospital mortality was also significantly higher in group I. Female gender (odds ratio (OR): 5.15, p<0.0001), emergency surgery (OR: 4.46, p<0.0001), and being over 70 years of age (OR: 4.67, p<0.0001) were found to be significant predictors for postoperative depression. CONCLUSION: The prognosis for patients who had depression developed after open heart surgery was poor. It might be important to start prophylactic medication as soon as possible after the operation, particularly for patients at risk of having depression.     

Tumor suppressive microRNA-375 regulates oncogene AEG-1/MTDH in head and neck squamous cell carcinoma (HNSCC)

Our microRNA (miRNA) expression signatures of hypopharyngeal squamous cell carcinoma, maxillary sinus squamous cell carcinoma and esophageal squamous cell carcinoma revealed that miR-375 was significantly reduced in cancer tissues compared with normal epithelium. In this study, we focused on the functional significance of miR-375 in cancer cells and identification of miR-375-regulated novel cancer networks in head and neck squamous cell carcinoma (HNSCC). Restoration of miR-375 showed significant inhibition of cell proliferation and induction of cell apoptosis in SAS and FaDu cell lines, suggesting that miR-375 functions as a tumor suppressor. We adopted genome-wide gene expression analysis to search for miR-375-regulated molecular targets. Gene expression data and luciferase reporter assays revealed that AEG-1/MTDH was directly regulated by miR-375. Cancer cell proliferation was significantly inhibited in HNSCC cells transfected with si-AEG-1/MTDH. In addition, expression levels of AEG-1/MTDH were significantly upregulated in cancer tissues. Therefore, AEG-1/MTDH may function as an oncogene in HNSCC. The identification of novel tumor suppressive miRNA and its regulated cancer pathways could provide new insights into potential molecular mechanisms of HNSCC oncogenesis.     

Tumour-suppressive microRNA-874 contributes to cell proliferation through targeting of histone deacetylase 1 in head and neck squamous cell carcinoma

Background:

Our recent studies of microRNA (miRNA) expression signature demonstrated that microRNA-874 (miR-874) was significantly downregulated in maxillary sinus squamous cell carcinoma (MSSCC), and a putative tumour-suppressive miRNA in human cancers. Our aim of this study was to investigate the functional significance of miR-874 in cancer cells and to identify novel miR-874-mediated cancer pathways and responsible genes in head and neck squamous cell carcinoma (HNSCC).

Methods:

Gain-of-function studies using mature miR-874 were performed to investigate cell proliferation and cell cycle distribution in HNSCC cell lines (SAS and FaDu). To identify miR-874-mediated molecular pathways and targets, we utilised gene expression analysis and in silico database analysis. Loss-of-function assays were performed to investigate the functional significance of miR-874 target genes.

Results:

Expression levels of miR-874 were significantly downregulated in HNSCC tissues (including oral, pharyngeal and laryngeal SCCs) compared with normal counterpart epithelia. Restoration of miR-874 in SAS and FaDu cell lines revealed significant inhibition of cell proliferation and induction of G2/M arrest and cell apoptosis. Our expression data and in silico analysis demonstrated that miR-874 modulated the cell cycle pathway. Moreover, histone deacetylase 1 (HDAC1) was a candidate target of miR-874 regulation. Luciferase reporter assays showed that miR-874 directly regulated HDAC1. Silencing of the HDAC1 gene significantly inhibited cell proliferation and induced G2/M arrest and cell apoptosis in SAS cells.

Conclusions:

Downregulation of miR-874 was a frequent event in HNSCC. miR-874 acted as a tumour suppressor and directly targeted HDAC1. Recognition of tumour-suppressive miRNA-mediated cancer pathways provides new insights into the potential mechanisms of HNSCC oncogenesis and suggests novel therapeutic strategies for the disease.     

The functional significance of microRNA-375 in human squamous cell carcinoma: aberrant expression and effects on cancer pathways

MicroRNAs (miRNAs) are a class of small, non-coding RNA molecules consisting of 19-22 nucleotides that are involved in a variety of biological processes, including development, differentiation, apoptosis and cell proliferation. In cancer research, a growing body of evidence has indicated that miRNAs are aberrantly expressed in many types of human cancers and can function either as tumor suppressors or oncogenes. Bioinformatic predictions suggest that miRNAs regulate more than 30% of protein-coding genes. Aberrant expression of miRNAs in cancer cells causes destruction of miRNA-regulated messenger RNA networks. Therefore, the identification of miRNA-regulated cancer pathways is important for understanding the molecular mechanisms of human cancer. Searching for the aberrant expression of miRNAs in cancer cells is the first step in the functional analysis of miRNAs in cancer cells. Genome-wide miRNA expression signatures can rapidly and precisely reveal aberrant expression of miRNA in cancers. The miRNA expression signatures of human cancers have revealed that miR-375 is significantly downregulated in cancer cells. Our recent data on maxillary sinus, hypopharyngeal and esophageal squamous cell carcinomas have suggested that miR-375 is frequently downregulated and functions as a tumor suppressor that targets several oncogenic genes in cancer cells. In this review, we focus on several types of human squamous cell carcinoma and describe the aberrant expression of miRNAs and the cancer pathways they regulate in these diseases.