Purpose: Peroxisome proliferator-activated receptor g (PPARg) plays a important role in various physiological functions.We examined whether PPARg is expressed in primary squamous cell carcinoma and lymph node metastasis and whether PPARg is a potential target for tumor therapy. Experimental Design and Results: A high-level expression of PPARg was observed in tumor cells of human primary squamous cell carcinoma, lymph node metastasis, and squamous cell carcinoma cell lines. Treatment with PPARg-specific antagonists, but not agonists, caused apoptotic cell death on squamous cell carcinoma cell lines in a concentration-dependent manner. Small interfering RNA for PPARg also inhibited cell adhesion and growth of squamous cell carcinomas. The phosphorylation of focal adhesion kinase (FAK) was decreased by treatment with PPARg antagonists, and resulted in decreases in phosphorylation of Erk and mitogen-activated protein kinase. Furthermore, PPARg antagonists decreased the adhesion of squamous cell carcinomas into fibronectin-coated plates, indicating the inhibition of interaction between squamous cell carcinomas and fibronectin. Expression of integrin a5, a counter adhesion molecule for fibronectin, was inhibited by the treatment with PPARg antagonists.These results indicate that the decrease in integrin a5 and following inhibition of cell adhesion may cause the inhibition of FAK signaling pathways. PPARg antagonists also strongly inhibited invasion of squamous cell carcinoma via down-regulation of CD151expression. Conclusions: The cell death caused by the PPARg antagonists was a result of direct interference with cell adhesion ''anoikis'' involving intracellular FAK signaling pathways. These results imply a potentially important and novel role for the inhibition of PPARg function via the use of specific antagonists in the treatment of squamous cell carcinoma and the prevention of tumor invasion and metastasis.

Aquaporins (AQP) play important roles in water and glycerol transport. We examined whether AQP3 is expressed in primary squamous cell carcinoma (SCC) such as esophageal and oral cancer and lymph node metastasis, and whether AQP3 is a potential target for tumor therapy. A high level expression of AQP3 was observed in tumor areas of human primary SCC such as esophageal and lingual cancers, and lymph node metastasis, but was not observed in normal areas. Treatment with pan-AQP inhibitor caused apoptotic cell death on the SCC cell lines in a concentration-dependent manner. Small interfering RNA (siRNA) specific for AQP3 also inhibited cell adhesion and growth of SCC, but not those of adenocarcinoma cell lines and fibroblasts. Expression of integrin a5 and b1, counter adhesion molecules for fibronectin, was inhibited by treatment with AQP3-siRNA. The phosphorylation of focal adhesion kinase (FAK) was decreased by treatment with AQP3-siRNA, which then caused decreases in phosphorylation of Erk and MAPK. These results indicate that the decreases in integrins and the inhibition of cell adhesion might cause inhibition of the FAK signaling pathways. Combination of AQP3-siRNA with cisplatin, a major anti-cancer drug, strongly inhibited the growth of SCC. Cell death caused by the inhibition of AQP3 was a result of direct interference with cell adhesion involving intracellular FAK-MAPK signaling pathways. These results imply a potentially important and novel role for the inhibition of AQP3 function via the use of specific siRNA in the treatment of SCC. (Cancer Sci 2011; 102: 1128-1136 H uman squamous cell carcinoma (SCC) is a major neoplasm in the esophagus or oral cavity and its incidence has recently been increasing.(1-3) The optimal treatment or therapy for early carcinoma is a surgical operation. However, overall survival remains largely unchanged.(1,3,4) Therefore, different therapies for the inhibition of tumor cell growth are required.The aquaporin (AQP) family is a membrane protein involved in the selective transport of water across cell membranes. Several subsets of AQP also transport small molecules such as glycerol and urea.(5-9) Among them, AQP3 is known to be expressed in various organs such as kidney, skin, lung and gastrointestinal tracts and to play important roles in the transport of water and glycerol. (10)(11)(12) Recent studies reported the expression of AQP3 in several cancers such as skin, lung and prostate. (13)(14)(15)(16)(17) However, there are few reports about the exact role of AQP3 on the cell growth of squamous cell carcinomas (SCC) such as esophageal or lingual cancers.We investigated whole genome analysis using a DNA microarray to find potential target genes that are involved in tumor cell growth, and reported the critical role of several important molecules on the cell growth of SCC. (18)(19)(20)(21) According to previous study and the results of a DNA microarray, we found that expression of AQP3 mRNA was observed in cell lines of SCC and the AQP3 expression level was altered by the inhibitio...

Members of theThe control of cell-extracellular matrix (ECM) adhesion is required for many physiological functions of stationary as well as motile cells in vivo (29). The integrin family of transmembrane proteins forms heterodimers that function as receptors for ECM proteins such as fibronectin. The engagement of integrins to the ECM triggers cascades of protein-protein interactions. Activation of protein tyrosine kinases (PTKs) such as Src family kinases and focal adhesion (FA) kinase (Fak) is one of the earliest events that immediately follow integrinfibronectin engagement (39). While Src localizes to endosomal membranes in quiescent cells, Src transiently translocates to newly formed FA structures during cell spreading onto a fibronectin-coated surface (32). It has also been shown that Src and Fyn, another member of the Src family, bind to Fak at tyrosine 397 (Y397) upon autophosphorylation (53). Inhibition of cell spreading by an endogenous inhibitor of Fak, Frnk (Fak-related nonkinase), can be bypassed by co-overexpression of Src, potentially due to the ability of Src to phosphorylate downstream FA proteins such as paxillin (49). These observations have raised the hypothesis that Src family kinases play a role in integrin signaling at the FA protein complex.Csk is a cytosolic tyrosine kinase that negatively regulates Src family kinases in vitro and in vivo by phosphorylating the regulatory tyrosine residue conserved among all members of the Src family (30,42). This phosphorylation is one of the requirements for the intramolecular conformational change that maintains Src family kinases structurally and catalytically inactive (65). Csk localizes to FA structures when Src family kinases are activated (25). Furthermore, consistent with activation of Src family kinases upon cell adhesion to fibronectin, Csk transiently accumulates at the integrin-cytoskeletal protein complex upon fibronectin-integrin engagement (39). Csk can associate with phosphorylated FA proteins such as Fak and paxillin in vitro, thus suggesting that Csk translocation to FA structures is regulated by tyrosine phosphorylation (5, 51). Thus, activation as well as regulation of Src family kinases appears to take place at the FA complex. To address this hypothesis, we have devised fusion proteins of Csk that constitutively localize to FAs. With this approach, we provide formal evidence for the previous prediction that Src family kinases are regulated positively or negatively at FAs. Ras and its effector Raf1 have been implicated in inhibition of integrin affinity in hematopoietic cells (28). Our results demonstrate for the first time that in contrast to overexpression of oncogenic Src, which can activate Ras and Raf1, endogenous Src family kinases play an essential role in integrin adhesive function and FA structures through Rap1 in fibroblastic cells. MATERIALS AND METHODSFAT constructs. FA-targeting (FAT) sequences were isolated from chicken Fak and mouse paxillin. The FAT sequence (encoding amino acids 854 to 1053) of chicken Fak was amplifie...

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The adapter protein Crk-Like (CrkL) can associate with the Src substrate p130Cas (

Intercellular adhesion molecule-1 (ICAM-1) is a transmembrane glycoprotein in the immunoglobulin superfamily, which plays an important role in cell adhesion and signal transduction. Although ICAM-1 is believed to play a role in several malignancies, it is still uncertain whether or not ICAM-1 expression contributes to cancer progression. In this study, we performed clinicopathological and cell biological analyses of ICAM-1 expression in oral squamous cell carcinoma (SCC). First, we examined the ICAM-1 expression in tongue SCC immunohistochemically, and revealed that ICAM-1 was expressed predominantly at the invasive front area of tongue SCC. ICAM-1 expression at the invasive front area was correlated with invasion, lymph node metastasis and increased blood and lymphatic vessel density of the tongue SCC. The relationship between ICAM-1 expression and clinicopathological factors were consistent with the increased proliferation, invasion and cytokine-production activities of ICAM-1-transfected SCC cells. Second, we analyzed the relationship between macrophages and ICAM-1-expressing tongue SCC cells because ICAM-1 is known to act as a ligand for adhesion of immune cells. Increased ICAM-1 expression in tongue SCC was correlated with increased macrophage infiltration within SCC nests. Moreover, macrophage/SCC-cell adhesion through ICAM-1 molecule was revealed using an in vitro cell adhesion and blockade assay. These findings indicate that ICAM-1 plays an important role in tongue SCC progression, which may result from the SCC-cell activity, angiogenic activity, lymphangiogenic activity and macrophage/SCC-cell adhesion.Intercellular adhesion molecule-1 (ICAM-1; also known as CD54) is a transmembrane glycoprotein in the immunoglobulin superfamily present at basal levels in a wide variety of cell types and is upregulated in response to a number of inflammatory mediators. During the inflammatory process, ICAM-1 expressed on endothelial cells interacts with the b2 integrin counter-receptors CD11a/CD18 (also known as lymphocyte function-associated antigen-1, LFA-1) and CD11b/ CD18 (also known as macrophage antigen-1, Mac-1) on the surface of immune cells, facilitating their transendothelial migration from the circulation to the site of inflammation.

(1-3) In contrast, ER-mediated signals critically affect the growth and progression of several cancers. In particular, the impact of estrogen signals on breast cancer is now well established. (4)(5)(6) Therefore, the current therapeutic strategy to treat ER-positive breast cancer relies on the blockade of ER-mediated signaling by an ER antagonist, such as tamoxifen.(4-6) However, the role of ER-signaling in other cancers is still unclear. In addition, the differences in expression patterns and the exact role of ERα and ERβ on cell growth, invasion and metastasis in various cancer cells have not been elucidated. (7)(8)(9) Human squamous cell carcinoma (SCC) is the most common neoplasm in the oral cavity cancer, and the incidence of lingual carcinoma has recently been increasing. The optimal treatment or therapy for carcinoma of the tongue remains a controversial issue, and surgical operation is still effective for SCC in the field of head and neck surgery. However, the recovery of lost function after a large surgical excision is accompanied by many problems such as speech impediment and dysphagia.(10) Local regional control of head and neck cancer has improved in recent decades. Nevertheless, overall survival remains largely unchanged. (11,12) The major reason for this discrepancy is distant metastasis and secondary neoplasms. (13,14)

More than 3 units of allogeneic red blood cells transfused might shorten the survival of patients with oral cavity cancer.