Manabu Iyoda

Epithelial cell transforming sequence 2 in human oral cancer.

Background Epithelial 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 Findings We 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/Significance Our 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.

State of heat shock factor 1 expression as a putative diagnostic marker for oral squamous cell carcinoma

Heat shock factor 1 (HSF1) is responsible for expres-- sion of a large class of heat shock proteins that have been implicated in the malignant phenotype of human cancers. Little is known about the effect of a high level of HSF1 on the behavior of oral squamous cell carcinoma (OSCC). In this study, we assessed the value of HSF1 for predicting clinical outcomes in OSCC. Quantitative reverse transcriptase-polymerase chain reaction and Western blotting showed that the expressions of HSF1 mRNA and protein in OSCC-derived cell lines (HSC-2, HSC-3, HSC-4, Sa3, Ca9-22, KON and Ho-1-u-1) were elevated compared with those in human normal oral keratinocytes (P<0.05). Similar to in vitro data, HSF1 mRNA expression in primary OSCCs (n=50) was significantly greater than in normal counterparts (P<0.05). Since HSF1 was observed in the nucleus and cytoplasm by immu-- nohistochemistry, we investigated the correlation between the HSF1 expression status at each subcellular location and the clinical behavior of OSCCs. Among the clinical classifications, higher nuclear HSF1 expression was closely related to tumor size and histopathologic types (P<0.05). These results showed for the first time that nuclear HSF1 expression may contribute to cancer progression and that HSF1 might be a potential diagnostic biomarker and a therapeutic target for OSCCs.

Dickkopf-1 in human oral cancer

Dickkopf-1 (Dkk1), a negative regulator of the Wnt signaling pathway, is implicated in tumorigenesis in several types of cancer. The purpose of this study was to determine the involvement of Dkk1 in oral squamous cell carcinoma (OSCC). We found that Dkk1 is frequently upregulated in OSCC-derived cell lines and primary OSCCs compared with normal counterparts. Unexpectedly, Dkk1-positive cases were correlated significantly (P<0.05) with a low risk of regional lymph node metastasis. We also found that cellular migration and invasiveness increased in Dkk1 knockdown cells and decreased in Dkk1 overexpressed cells. Furthermore, we investigated the relationship between the expression of Dkk1 and distribution of β-catenin in OSCC cells, since the Wnt signaling pathway is related closely to β-catenin. Whereas alteration of the β-catenin levels was not observed in each subcellular fractionation, the phosphorylated β-catenin levels in nuclei increased in Dkk1 knockdown cells and decreased in Dkk1 overexpressed cells. These data indicated that the high phosphorylation level of β-catenin in nuclei was correlated with a high risk of tumor invasiveness. The current study suggested that Dkk1 plays an important role in regulating cellular migration and invasiveness, making Dkk1 a potential biomarker for early detection of lymph node metastasis in OSCCs.

Semaphorin7A Promotion of Tumoral Growth and Metastasis in Human Oral Cancer by Regulation of G1 Cell Cycle and Matrix Metalloproteases: Possible Contribution to Tumoral Angiogenesis.

Background Semaphorins (SEMAs) consist of a large family of secreted and membrane-anchored proteins that are important in neuronal pathfinding and axon guidance in selected areas of the developing nervous system. Of them, SEMA7A has been reported to have a chemotactic activity in neurogenesis and to be an immunomodulator; however, little is known about the relevance of SEMA7A in the behaviors of oral squamous cell carcinoma (OSCC). Methods We evaluated SEMA7A expression in OSCC-derived cell lines and primary OSCC samples using quantitative reverse transcriptase-polymerase chain reaction, immunoblotting, and semiquantitative immunohistochemistry (sq-IHC). In addition, SEMA7A knockdown cells (shSEMA7A cells) were used for functional experiments, including cellular proliferation, invasiveness, and migration assays. We also analyzed the clinical correlation between SEMA7A status and clinical behaviors in patients with OSCC. Results SEMA7A mRNA and protein were up-regulated significantly (P<0.05) in OSCC-derived cell lines compared with human normal oral keratinocytes. The shSEMA7A cells showed decreased cellular growth by cell-cycle arrest at the G1 phase, resulting from up-regulation of cyclin-dependent kinase inhibitors (p21Cip1 and p27Kip1) and down-regulation of cyclins (cyclin D1, cyclin E) and cyclin-dependent kinases (CDK2, CDK4, and CDK6); and decreased invasiveness and migration activities by reduced secretion of matrix metalloproteases (MMPs) (MMP-2, proMMP-2, pro-MMP-9), and expression of membrane type 1- MMP (MT1-MMP). We also found inactivation of the extracellular regulated kinase 1/2 and AKT pathways, an upstream molecule of cell-cycle arrest at the G1 phase, and reduced secretion of MMPs in shSEMA7A cells. sq-IHC showed that SEMA7A expression in the primary OSCCs was significantly (P = 0.001) greater than that in normal counterparts and was correlated with primary tumoral size (P = 0.0254) and regional lymph node metastasis (P = 0.0002). Conclusion Our data provide evidence for an essential role of SEMA7A in tumoral growth and metastasis in OSCC and indicated that SEMA7A may play a potential diagnostic/therapeutic target for use in patients with OSCC.

Targeting phosphodiesterase 3B enhances cisplatin sensitivity in human cancer cells

We previously reported that human squamous cell carcinoma (SCC) cell lines refractory to cis‐diaminedichloro‐platinum II (cisplatin [CDDP]) had significant upregulation of the phosphodiesterase 3B gene (PDE3B), suggesting that inhibiting PDE3B suppresses CDDP resistance. shRNA‐mediated PDE3B depletion in CDDP‐resistant cells derived from SCC cells and Hela cells and induced CDDP sensitivity and inhibited tumor growth with elevated cyclic GMP induction resulting in upregulation of the multidrug‐resistant molecule, but this did not occur in the 5‐fluorouracil‐resistant hepatocellular carcinoma cell lines. Furthermore, the antitumor growth effect of the combination of a PDE3B inhibitor (cilostazol) and CDDP in vivo was also greater than with either cilostazol or CDDP alone, with a significant increase in the number of apoptotic and cell growth‐suppressive cancer cells in CDDP‐resistance cell lines. Our results provided novel information on which to base further mechanistic studies of CDDP sensitization by inhibiting PDE3B in human cancer cells and for developing strategies to improve outcomes with concurrent chemotherapy.

SIPA1 promotes invasion and migration in human oral squamous cell carcinoma by ITGB1 and MMP7

ABSTRACT Signal‐induced proliferation‐associated protein 1 (SIPA1) is known to be a GTPase activating protein. Overexpressed SIPA1 is related to metastatic progression in breast and prostate cancers; however, the relevance of SIPA1 in oral squamous cell carcinoma (OSCC) is still unknown. The aim of this study was to examine SIPA1 expression and its functional mechanisms in OSCC. SIPA1 mRNA and protein expressions were analyzed by quantitative reverse transcriptase‐polymerase chain reaction, Western blot analysis, and immunohistochemistry. The expressions of SIPA1 were up‐regulated significantly in vitro and in vivo. Moreover, SIPA1 expression was correlated with regional lymph node metastasis. We next assessed the cellular functions associated with tumoral metastasis using SIPA1 knockdown (shSIPA1) cells and analyzed the downstream molecules of SIPA1, i.e., bromodomain containing protein 4(BRD4), integrin beta1 (ITGB1), and matrix metalloproteinase 7 (MMP7). The shSIPA1 cells showed decreased invasiveness and migratory activities, however cellular adhesion ability was maintained at a high level. In addition, ITGB1 expression was greater in shSIPA1 cells, whereas MMP7 expression was lower than in control cells. This research is the first to establish that SIPA1 promotes cancer metastasis by regulating the ITGB1 and MMP7. Therefore, SIPA1 might be a novel therapeutic target for patients with lymph node metastasis of OSCC. HighlightsSIPA1 expression was up‐regulated in oral squamous cell carcinoma (OSCC).SIPA1‐positive OSCCs were correlated with regional lymph node metastasis.SIPA1 controlled BRD4 and influenced transcription of ITGB1and MMP7.SIPA1 induced cellular invasion and migration and decreased cellular adhesion.SIPA1 might be a potential biomarker of cancer metastasis for OSCC.

Antitumor activity of satraplatin in cisplatin-resistant oral squamous cell carcinoma cells

The aim of the current study was to identify the antitumor activity of satraplatin in paired cisplatin (CDDP)‐resistant oral squamous cell carcinoma (OSCC) cell line and its parental cell line.

Gibberellic acid induces α-amylase expression in adipose-derived stem cells.

Salivary α-amylase is the most important enzyme for oral digestion of dietary starch. Therefore, regeneration of the salivary glands via a tissue engineering approach is clearly required for patients with salivary gland dysfunction. Early during seed germination, the embryo synthesizes gibberellic acid (GA3), a plant hormone that activates the synthesis and secretion of α-amylase. The purpose of this study was to explore an approach for differentiation of stem cells into salivary glands using GA3. We isolated adipose-derived stem cells (ASCs), which are positive for mesenchymal stem cell markers (CD73, CD90 and CD105) and possess pluripotency to osteoblasts, adipocytes and neural cells, from human buccal fat pads, which are a readily available source for dentists and oral surgeons. In addition, we investigated the cytotoxicity of GA3 for human ASCs. GA3 neither affects cell morphology nor cell viability in a dose- or time-dependent manner. ASCs were incubated with GA3 to assess mRNA and protein expression of α-amylase by reverse transcriptase-polymerase chain reaction and western blot analyses. α-amylase mRNA expression on 21 days after treatment with GA3 (1 mM) was seven times greater than that in resting condition (Day 0). While we did not detect α-amylase bands on Day 0, α-amylase protein was detectable 7 days after treatment with GA3, reaching a maximal level on Day 21. Our results indicated that GA3 can increase cellular α-amylase expression and that our induction method would be useful for therapeutic application for salivary gland regeneration.

Critical role of deoxynucleotidyl transferase terminal interacting protein 1 in oral cancer

Deoxynucleotidyl transferase terminal interacting protein 1 (DNTTIP1) forms a complex with histone deacetylase (HDAC); however, the relevance of DNTTIP1 in cancer remains unknown. The aim of this study was to examine DNTTIP1 expression and its functional mechanisms in oral squamous cell carcinomas (OSCCs). DNTTIP1 expression was analyzed by quantitative reverse transcriptase-polymerase chain reaction, immunoblotting analysis, and immunohistochemistry. The expression of DNTTIP1 was upregulated significantly in vitro and in vivo, and in patients with OSCC in whom DNTTIP1 was overexpressed and the expression level was correlated significantly (P < 0.05) with tumoral growth. DNTTIP1 knockdown (siDNTTIP1) cells showed depressed cellular proliferation by cell-cycle arrest at the G1 phase with high acetylation of p53 and upregulation of p21Cip1. Moreover, resveratrol, a HDAC inhibitor, controlled not only acetylated p53 status but also DNTTIP1 expression, leading to a similar phenotype of siDNTTIP1 cells. A marked (P < 0.05) reduction of tumoral growth in mouse xenograft models was observed with lower DNTTIP1 expression under the presence of this chemical reagent. Taken together, our results suggested that DNTTIP1–HDAC interaction promotes tumoral growth through deacetylation of p53 and that DNTTIP1 might be a critical therapeutic target in OSCCs.This study demonstrates that deoxynucleotidyl transferase terminal interacting protein 1 (DNTTIP1), a binding partner of histone deacetylase (HDAC), plays a crucial role in progression of oral squamous cell carcinoma (OSCC) by controlling p53 acetylation. Resveratrol, a HDAC inhibitor, controls both acetylated p53 status and DNTTIP1 expression. Thus, DNTTIP1 might be a novel therapeutic target in OSCC.

Multiple coagulation factor deficiency protein 2 as a crucial component in metastasis of human oral cancer

ABSTRACT Multiple coagulation factor deficiency protein 2 (MCFD2), a binding partner of lectin mannose binding 1 (LMAN1), causes combined deficiencies of coagulation factors V and VIII. MCFD2 function in inherited hematologic disorders is well elucidated; however, little is known about its role in human tumorigenesis. The aim of the current study was to investigate the states of MCFD2 in oral squamous cell carcinoma (OSCC). The expression of MCFD2 was up‐regulated significantly in all cell lines examined. Evaluation of the cellular functions associated with tumoral metastasis showed that MCFD2 knockdown (shMCFD2) cells exhibited significantly lower cellular invasiveness and migration and higher cellular adhesion compared with shControl cells. Of note, shMCFD2 cells also showed weak immunoreactivity of LMAN1 and a lower secretion level of galactoside‐binding soluble 3 binding protein (LGALS3BP). In addition to in vitro validation, clinical data on 70 patients with OSCC indicated that state of MCFD2 expression level is associated with regional lymph node metastasis. Altogether, we have demonstrated that MCFD2 promotes cancer metastasis by regulating LMAN1 and LGALS3BP expression levels. Hence, MCFD2 may represent a promising candidate for a novel therapeutic target for patients with metastatic OSCCs. HighlightsExpression of MCFD2 was up‐regulated in human oral squamous cell carcinoma (OSCC).MCFD2 expression is associated with regional lymph node metastasis.MCFD2 induced cellular invasion and migration and decreased cellular adhesion.MCFD2 regulated secretion of galectin 3 binding protein via MCFD2‐LMAN1 interaction.MCFD2 might be a novel therapeutic target for patients with metastatic OSCCs.