Abstract. To characterize cancer-related gene expression changes in oral squamous cell carcinomas (OSCCs), we compared the gene expression profiles in OSCC-derived cell lines with human normal oral keratinocytes (HNOKs). Microarray analysis identified 166 genes that were up-regulated in OSCC-derived cell lines. Gene ontology analysis showed that cancer-related function had the highest significance. Among the genes mapped to the cancer-related network with the highest significance, the receptor for hyaluronan-mediated motility (RHAMM) was evaluated further for mRNA and protein expression in the OSCC cell lines, primary OSCCs. Overexpression of RHAMM protein was observed in all cell lines compared to HNOKs. Immunohistochemical analysis showed highly expressed RHAMM in primary OSCCs, whereas most corresponding normal tissues had no or significant down-regulation of protein immunoreactivity. Real-time quantitative reverse transcriptase-polymerase chain reaction data agreed with the protein expression. Moreover, the RHAMM expression status was correlated with the TNM stage (P<0.001). The results suggested that RHAMM expression may be correlated with tumor aggressiveness and offer clues to the development of new treatments for human OSCCs.

BackgroundEpithelial cell transforming sequence 2 (ECT2) is a guanine nucleotide exchange factor for Rho family GTPase, which has been implicated in the malignant phenotype of human cancers. Little is known about the effect of a high level of ECT2 in regulating oral cancer cell behavior. In this study, we investigated the involvement of ECT2 in oral squamous cell carcinoma (OSCC).Methodology/Principal FindingsWe analyzed ECT2 expression in OSCC-derived cell lines and primary OSCCs compared with matched normal tissue (n = 96) by quantitative reverse transcriptase-polymerase chain reaction, Western blot, and immunohistochemistry. We then evaluated the correlation between the ECT2 expression status in primary OSCCs and the clinicopathological features. ECT2 expression was significantly up-regulated in OSCCs in vitro and in vivo (p<0.05). Among the clinical variables analyzed, higher ECT2 expression also was associated with the TNM stage grading (p<0.05). When we performed functional analyses of ECT2 in OSCC-derived cells using the shRNA system, the cellular proliferation of the ECT2 knockdown cells decreased significantly compared with the control cells (p<0.05). Cell cycle analysis by flow cytometry showed arrest of cell cycle progression at the G1 phase in the ECT2 knockdown cells. We also found up-regulation of the Cip/Kip family of the cyclin-dependent kinase inhibitors, p21cip1 and p27kip1, and down-regulation of cyclin D1, cyclin E, and CDK4. These data suggested that the elevated Cip/Kip family induced inhibition of the cyclin D1-CDK complex activity leading to cell cycle arrest at the G1 phase.Conclusions/SignificanceOur results proposed for the first time that ECT2 is an indicator of cellular proliferation in OSCCs and that ECT2 might be a potential therapeutic target for the development of new treatments for OSCCs.

To identify genes associated with radioresistant oral squamous cell carcinoma (OSCC), we compared gene expression signatures between OSCC cell lines exhibiting radioresistance and cells with radiosensitivity after X-ray irradiation in a dose-dependent manner using Affymetrix GeneChip analysis with Human Genome-U133 plus 2.0 GeneChip. The microarray data identified 167 genes that were significantly overexpressed in radioresistant cells after X-ray irradiation. Among the genes identified, 40 were mapped to 3 highly significant genetic networks identified by the Ingenuity Pathway Analysis tool. Gene ontology analysis showed that cancer-related function had the highest significance. The 40 genes included 25 cancer-related genes that formed 1 network and were categorized by function into growth and proliferation, apoptosis, and adhesion. Furthermore, real-time quantitative reverse transcriptase-polymerase chain reaction showed that the mRNA expression levels of the 25 genes were higher in radioresistant cells than in radiosensitive cells in a dose-dependent manner and in a time-dependent manner. Our results suggest that the identified genes help to elucidate the molecular mechanisms of the radioresistance of OSCC and could be radiotherapeutic molecular markers for choosing the appropriate radiotherapy for this disease. ' 2007 Wiley-Liss, Inc.

BackgroundGelsolin-like actin-capping protein (CapG) is a ubiquitous gelsolin-family actin-modulating protein involved in cell signalling, receptor-mediated membrane ruffling, phagocytosis, and motility. CapG has generated great interest due to its oncogenic function in the control of cell migration or invasion in a variety of cancer cells. We previously applied proteomic methods to characterize differentially expressed proteins in oral squamous-cell carcinoma (OSCC) cells and detected significantly high expression levels of CapG in OSCC-derived cell lines compared to human normal oral keratinocytes. In the current study, to further determine the potential involvement of CapG in OSCC, we evaluated the status of CapG protein and mRNA expression in human oral premalignant lesions (OPLs) and primary OSCCs and correlated the results with clinicopathologic variables.MethodsMatched normal and tumour tissue sections of 79 human primary OSCCs and 28 OPLs were analyzed for CapG expression by immunohistochemistry (IHC). Correlations between CapG-immunohistochemical staining scores of OSCCs and clinicopathologic features were evaluated by Fisher's exact test. Real-time quantitative reverse transcriptase-polymerase chain reaction (qRT-PCR) was used to estimate CapG expression at the mRNA level.ResultsIn IHC, substantial up-regulation of CapG protein was observed in primary OSCCs (52%) and OPLs (64%), whereas corresponding normal tissues showed consistently weak or absent immunoreactivity of CapG. qRT-PCR data were consistent with the protein expression status. Moreover, CapG expression was correlated with the TNM stage grading of OSCCs.ConclusionOur finding of frequent dysregulated expression of CapG in premalignant and malignant lesions together with an association with an advanced clinical disease stage suggests that CapG could contribute to cancer development and progression and that CapG may have potential as a biomarker and a therapeutic target for OSCC.

Aneurysms located at the distal portion of the anterior inferior cerebellar artery (AICA) are rare, and their clinical features are not fully understood. We report the clinical features and management of nine distal AICA aneurysms in nine patients treated during the past decade at Kagoshima University Hospital and affiliated hospitals. Our series includes seven women and two men. Of their nine aneurysms, eight were ruptured and one was unruptured; six were saccular and three were dissecting aneurysms. The most prevalent location was the meatal loop (n = 5) followed by the postmeatal (n = 3) and premeatal segment (n = 1) of the AICA, suggesting hemodynamic stress as an etiology of these distal AICA aneurysms. Of the nine patients, five presented with angiographic features suggestive of increased hemodynamic stress to the AICA and the common trunk of the posterior inferior cerebellar artery, with vertebral artery stenosis, marked laterality, and a primitive hypoglossal artery. We addressed eight aneurysms (eight patients) surgically; one aneurysm in one patient disappeared in the course of 3 months without surgical treatment. Of the eight surgically treated aneurysms, seven were ruptured and one was unruptured, five were clipped via lateral suboccipital craniotomy, two were trapped via lateral suboccipital craniotomy, and one was embolized. Good outcomes were obtained in six of the eight patients who underwent operation (75 %). We consider increased hemodynamic stress attributable to anatomic variations in the AICA and related posterior circulation to be the predominant contributor to the development of distal AICA aneurysms. Direct clipping and trapping yielded favorable outcomes in our series.