carcinoma is an epithelial cancer with a 20020776 remarkable geographic and racial distribution worldwide. Mounting evidence suggests that NPC tumorigenesis could result 2575813 from environmental conditions and genetic factors. Tumorigenesis is a multi-step and multi-factor process that commonly involves the inactivation of several tumor suppressor genes and abnormal activation of several oncogenes. Comparative genomic hybridization and loss of heterozygosity have provided a comprehensive view of the gross genomic changes linked with NPC and revealed several new sites of genomic imbalance, indicating the possible involvement of novel oncogenes/tumor suppressor genes in the carcinogenesis of NPC. However, the mechanisms of NPC tumorigenesis remain unclear. In our previous study, we performed suppression subtractive hybridization and cDNA microarray hybridization of NPC biopsies and nontumor nasopharyngeal epithelial tissues. We identified two PLUNC family members, SPLUNC1 and LPLUNC1 that were down-regulated in NPC, suggesting that the abnormal expression of SPLUNC1 and LPLUNC1 may be important molecular events in NPC development. SPLUNC1 and LPLUNC1 are members of the PLUNC family, which is predominantly expressed in the upper airways, nose and mouth, and they are located on a single locus on chromosome 20. The PLUNC proteins are secreted and categorized into short and long forms, which contain domains LPLUNC1 Inhibits Cell Growth via MAP Kinase that are structurally similar to one or two domains of protein/lipid binding protein, respectively. SPLUNC1 was originally found to be down-regulated in NPC and exhibits host defense properties. SPLUNC1 is secreted by large airway epithelial cells and has been shown to possess antimicrobial and anti-inflammatory functions. LPLUNC1 belongs to the bactericidal permeability increasing BPI/LBP family, and its expression is reduced in NPC. However, the function of LPLUNC1 in NPC remains unknown. Immunohistochemistry Immunohistochemistry was performed using the peroxidase antiperoxidase technique after a microwave antigen retrieval procedure. The sections were incubated with mouse antihuman LPLUNC1, extracellular signal-regulated kinase, c-Jun NH2terminal protein kinase, c-MYC, c-Jun, cyclin-dependent kinase 4 or p27 antibodies overnight at 4uC. A semiquantitative scoring criterion for IHC was used, in which both staining intensity and positive areas were recorded. Materials and Methods Ethics Statement Before study initiation, ethical approval was obtained from the Cancer Hospital 
of the Hunan province in Changsha and the Central South University Ethics Review committees/Institutional Review Boards. NPC samples, nontumor nasopharyngeal epithelial tissues and peripheral blood lymphocytes from normal volunteers were collected at the Cancer Hospital of the Hunan province. Written informed consent was obtained from all patients and volunteers. All RS-1 biological activity animal procedures were conducted in accordance with protocols approved by the Institutional Animal Care and Use Committee of Central South University. Animals were allowed access to standard chow diet and water ad libitum and were housed in a pathogen-free barrier facility with a 12L:12D cycle. The mice were sacrificed by CO2 asphyxiation. Chemicals, Cell Culture, Plasmids and Stable Transfection Lipopolysaccharides from Escherichia coli 0111:B4 were purchased from Sigma, and mitogenactivated protein kinase kinase inhibitor U0126 was purchased from the Cell Signaling Technolo
