. Moreover, LMP1 induces HIF-1 DNA binding activity and upregulates HRE and VEGF promoter transcriptional activity. Finally, LMP1 increases the appearance of VEGF protein in extracellular fluids; induction of VEGF is suppressed by PD98059 or catalase. These results suggest that LMP1 increases HIF-1 activity through induction of HIF-1␣ protein expression, which is controlled by p42/p44 MAPK activity and H 2 O 2 . The ability of EBV, and specifically its major oncoprotein, LMP1, to induce HIF-1␣ along with other invasiveness and angiogenic factors reported previously discloses additional oncogenic properties of this tumor virus.

Cyclooxygenase-2 (COX-2) is an inducible form of COX and is overexpressed in diverse tumors, raising the possibility of a role for COX-2 in carcinogenesis. In addition, COX-2 contributes to angiogenesis. The Epstein–Barr virus (EBV) oncoprotein, latent membrane protein 1 (LMP1), is detected in at least 70% of nasopharyngeal carcinoma (NPC) and all EBV-infected preinvasive nasopharyngeal lesions. We found that in specimens of LMP1-positive NPC, COX-2 is frequently expressed, whereas LMP1-negative NPC rarely express the enzyme. We next found that expression of LMP1 in EBV-negative nasopharyngeal epithelial cells induced COX-2 expression. Coexpression of IκBα(S32A/S36A), which is not phosphorylated and prevents NF-κB activation, with LMP1 showed that NF-κB is essential for induction of COX-2 by LMP1. We also demonstrate that NF-κB is involved in LMP1-induced cox-2 promoter activity with the use of reporter assays. Two major regions of LMP1, designated CTAR1 and CTAR2, are signal-transducing domains of LMP1. Constructs expressing either CTAR1 or CTAR2 induce COX-2 but to a lesser extent than wild-type LMP1, consistent with the ability of both regions to activate NF-κB. Furthermore, we demonstrate that LMP1-induced COX-2 is functional because LMP1 increased production of prostaglandin E 2 in a COX-2-dependent manner. Finally, we demonstrate that LMP1 increased production of vascular endothelial growth factor (VEGF). Treatment of LMP1-expressing cells with the COX-2-specific inhibitor (NS-398) dramatically decreased production of VEGF, suggesting that LMP1-induced VEGF production is mediated, at least in part, by COX-2. These results suggest that COX-2 induction by LMP1 may play a role in angiogenesis in NPC.

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Cisplatin (CDDP) has been a key drug for chemotherapy in patients with head and neck squamous cell carcinoma. Nephrotoxicity is one of its adverse reactions that are dose limiting. To increase its antitumor effects and reduce such toxicity problems, polymeric micelles carrying CDDP (NC-6004) have been developed. The present study was designed to evaluate the efficacy and safety of NC-6004 for oral squamous cell carcinoma. In vitro antitumor activity was assayed in four oral squamous cell carcinoma cell lines. To investigate the antitumor and nephrotoxic effects of NC-6004, nude mice bearing OSC-19 were administered NC-6004 or CDDP. The in vitro growth-inhibitory effect of NC-6004 was significantly less than that of CDDP. However, both NC-6004 and CDDP showed equivalent antitumor effects in vivo. Mice with CDDP developed renal cell apoptosis; however, those injected with NC-6004 were almost free of renal cell injury. Moreover, in an orthotopic tongue cancer model using OSC-19, NC-6004 reduced the rate of sentinel lymph node metastasis to lower than that with CDDP. In conclusion, considering the potential advantages in terms of noticeable antitumor activity, lymphatic drug delivery and reduced nephrotoxicity, NC-6004 represents a significant structural improvement in the development of a platinum complex. (Cancer Sci 2013; 104: 369-374) H ead and neck cancer remains a significant public health problem and ranks in the six leading cancers by incidence worldwide, with an estimated 600 000 new cases every year.(1) Cisplatin (cis-dichlorodiammineplatinum; CDDP) has been demonstrated to be one of the most effective cytotoxic agents (2) and the CDDP-based chemotherapy regimen has gained widespread use in patients with head and neck squamous cell carcinoma (HNSCC). However, its administration has been hindered by its adverse reactions, for example, nephrotoxicity, neurotoxicity, gastrointestinal toxicity, hematological toxicity and ototoxicity.(3) Among these, the significant risk of nephrotoxicity frequently hinders the use of high doses to maximize its antineoplastic effects, which might be the cause of treatment failure.To overcome these problems and improve the therapeutic effect of CDDP, we have been applying superselective supradose intra-arterial CDDP infusion for advanced HNSCC. However, since this technique is more complicated than that of i.v. infusion of antitumor drugs, it is not prevalent in the chemotherapy scene. Recently, several kinds of nanoparticle therapeutic platforms, including liposomes, nanoparticles and polymeric micelles, have been developed based on the idea that the drug delivery system (DDS) can accumulate in the tumor selectively, with reduced distribution in normal tissues and minimized undesirable side-effects.(5-7) NC-6004, which is a CDDP-incorporating polymeric micellar nanoparticle, enhanced antitumor activity and reduced the nephrotoxicity and neurotoxicity of CDDP in gastric cancer. (8)(9)(10) Poly(ethylene glycol)-poly(glutamic acid) block copolymers (PEG-P [Gu]) confer a stealth...

Recent studies suggest the existence of cancer stem cells (CSC) and cancer progenitor cells (CPC), although strict definitions of neither CSC nor CPC have been developed. We have produced evidence that the principal oncoprotein of Epstein-Barr virus (EBV), latent membrane protein 1 (LMP1), which is associated with human malignancies, especially nasopharyngeal carcinoma (NPC), promotes tumor cell invasion and metastasis, as well as the epithelial-mesenchymal transition (EMT). However, whether LMP1 is involved in the development of CSC/CPC is still unclear. This study investigates whether the expression of EBV-LMP1 is related to the development of CSC/CPC. Analysis of cancer stem cell markers reveals that LMP1 induces the CD44 high CD24low CSC/CPC-like phenotype as well as self-renewal abilities in LMP1-expressing epithelial cell lines. In addition, we show here that LMP1 induction in epithelial cells causes high tumorigenicity and rapid cellular proliferation. Furthermore, we found that LMP1 expression increased the expression of several CPC markers as well as producing increased levels of EMT markers. Our findings indicate that LMP1 can induce a CPC-like rather than a CSC-like phenotype in epithelial cells and suggest that LMP1-induced phenotypic changes contribute to the development of NPC.Recent studies have proposed that solid tumors are organized as a hierarchy composed of a spectrum of phenotypically distinct cells at different stages of maturation (25,26). The concept that cancer stem cells (CSC) include primitive rare CSC and cancer progenitor cells (CPC) has been developed (25). At the apex of the hierarchy are primitive rare CSC, which possess extended self-renewal capabilities that allow them to perpetuate themselves and develop into CPC. CPC have only limited self-renewal abilities and can, in turn, differentiate into various types of cancer cells. In vivo, the primitive rare CSC rarely divide, whereas CPC proliferate rapidly. CD44 high CD24 low cells from breast cancer tissues were found to be more tumorigenic in immunodeficient mice than CD44 low CD24 high cells, and the results of these observations were used to support the CSC hypothesis for solid tumors (1). Immortalized human mammary epithelial cells undergoing an epithelial-mesenchymal transition (EMT) are CSC-like, as evidenced by their CD44 high CD24 low phenotype and their capacity for self-renewal and for forming mammospheres (20). Thus, the conjunction of EMT and the CD44 high CD24 low phenotype appears to be important for the understanding of CSC-like characteristics, although CSC have been characterized in solid tumors by using a variety of stem cell markers (9, 10, 33). Epstein-Barr virus (EBV) is a human herpesvirus that is associated with several malignancies, such as Burkitt lymphoma (BL), Hodgkin lymphoma (HL), gastric cancer, and, most importantly, nasopharyngeal carcinoma (NPC) (24). In all these tumors, EBV infection is predominantly latent. In latent infection, expressed EBV genes are restricted to six EBV nuclear antigens (EBNA...