Here, tumor-infiltrating CD11b(+) myelomonocytoid cells in murine colon adenocarcinoma-38 and GL261 murine glioma were phenotypically characterized. Over 90% were of the CD11b(+)F4/80(+) monocyte/macrophage lineage. They also had a myeloid-derived suppressor cell (MDSC) phenotype, as they suppressed the proliferation of activated splenic CD8(+) T cells and had a CD11b(+)CD11c(+)Gr-1(low)IL-4Ralpha(+) phenotype. In addition, the cells expressed CX(3)CR1 and CCR2 simultaneously, which are the markers of an inflammatory monocyte. The MDSCs expressed CD206, CXCL10, IL-1beta, and TNF-alpha mRNAs. They also simultaneously expressed CXCL10 and CD206 proteins, which are typical, classical (M1) and alternative (M2) macrophage activation markers, respectively. Peritoneal exudate cells (PECs) strongly expressed CD36, CD206, and TGF-beta mRNA, which is characteristic of deactivated monocytes. The MDSCs also secreted TGF-beta, and in vitro culture of MDSCs and PECs with anti-TGF-beta antibody recovered their ability to secrete NO. However, as a result of secretion of proinflammatory cytokines, MDSCs could not be categorized into deactivated monocyte/macrophages. Thus, tumor-infiltrating MDSCs bear pleiotropic characteristics of M1 and M2 monocytes/macrophages. Furthermore, CD206 expression by tumor-infiltrating MDSCs appears to be regulated by an autocrine mechanism that involves TGF-beta.

A recent global gene expression profiling study unexpectedly showed that activated oncogenic NRAS may recruit neural precursor cell expressed, developmentally downregulated 4L (Nedd4L; a human homologue of Nedd4-2) in cultured melanoma cells. However, whether Nedd4L was expressed in melanoma tissues or participated in melanoma carcinogenesis remains to be clarified. Here, we investigated the expression status of Nedd4L in human melanocytes, benign nevi and melanoma tissue specimens and subsequently attempted to determine the role of Nedd4L in melanoma cell growth. Immunohistochemical staining revealed that Nedd4L was not present in any non-tumorous melanocytes or in 18 benign nevi tissues, but it was detected in 34 of 79 cutaneous melanomas and 9 of 32 nodal metastatic melanomas. Downregulation of Nedd4L significantly reduced the growth of cultured G361 melanoma cells in vitro. Moreover, exogenous Nedd4L expression significantly promoted the growth of A2058 melanoma cells in vivo in a xenograft assay. The present findings indicate that Nedd4L expression may be increased to facilitate tumour growth in many melanomas.

Zfp191 represses differentiation and keeps various cells in the stem/progenitor stage. Here, we report that a Zfp191 homolog protein, ZNF396, is expressed in basal cell carcinoma (BCC) and possibly represses the expression of a Notch system effector molecule, Hes1 (hairy and enhancer of split-1), and prevents BCC cells from undergoing Notch-mediated squamous cell differentiation. ZNF396 immunoreactivity was found in the nucleus of 35 of 38 cutaneous BCC and 4 of 74 squamous cell carcinoma tissue specimens. In non-tumorous epidermal tissues, ZNF396 immunoreactivity was restricted in basal cells. siRNA-mediated silencing of ZNF396 induced the expression of Notch2, Hes1, and involucrin in cultured BCC cells. Finally, we found that siRNA-mediated silencing of ZNF396 gene inhibited the proliferation of TE354.T basal cell carcinoma cells. ZNF396 might repress Notch-Hes1 signaling axis and prevent tumor cells from undergoing squamous differentiation in BCC.

Abstract. Macrophages demonstrate plasticity, and tumorassociated macrophages (TAM) can function as immunosuppressive cells in the tumor microenvironment. Therefore, in this study, we aimed to reprogram TAM in vitro with cytokine signal alteration. Granulocyte macrophage colony stimulating factor (GM-CSF) treatment alone did not lead to changes in the expression of M1 (including IL-1β, TNFα and CXCL-10) or M2 (including CD36, CD206 and CCL17) molecules by TAM in vitro, although they adopted a round morphology and were less adhesive to the culture dish. When macrophage colony stimulating factor (M-CSF) signals were suppressed by siRNA against the M-CSF receptor (M-CSFR) in conjunction with GM-CSF treatment, the signal transduction pathway of TAM was altered, and the expression of STAT1, STAT5 and STAT6, which are usually expressed by dendritic cells, was increased. However, the same treatment did not alter the TAM expression pattern of M1/M2 marker molecules. With respect to the NF-κB pathway, GM-CSF and M-CSFR siRNA combination treatment significantly induced the expression of p65, which is usually not expressed by TAM, while p50 and p105 expression by TAM was not affected by the treatment. These findings indicate that our model could not redirect TAM to a monocyte-derived dendritic cell-like phenotype based on the analysis of M1/M2 marker expression, but it was able to modify cell signaling pathways toward a dendritic cell-like pattern. Therefore, the present data suggest that TAM demonstrate plasticity toward dendritic cell-like signal transduction patterns, and that the alteration of the tumor microenvironment has the potential to reverse the immunosuppressive properties of TAM.