title: CCR7-expressing B16 melanoma cells downregulate interferon-γ-mediated inflammation and increase lymphangiogenesis in the tumor microenvironment.
abstract: The expression of the CC chemokine receptor-7 (CCR7) by cancers, including melanoma, augments lymph node (LN) metastasis, but little is known about its role in lymphangiogenesis and anti-tumor immunity. We injected control B16 murine melanoma cells (pLNCX2-B16) and CCR7-overexpressing B16 cells (CCR7-B16) in murine footpads and compared resulting tumors at the protein and mRNA level using immunostaining, Affymetrix gene microarray and quantitative reverse-transcriptase PCR. Although control and CCR7-B16 primary tumors were of similar size, LN metastasis was dramatically enhanced in CCR7-B16 tumors. Microarray analysis of leukocyte-depleted pLNCX2-B16 and CCR7-B16 tumor cell suspensions showed that three major groups of genes linked to interferon (IFN)-γ signaling pathways (for example, STAT1, CXCR 9-11, CCL5 and CXCL10, major histocompatibility complex (MHC) I and MHC II) were downregulated in the CCR7-B16 tumor microenvironment, suggesting activation through CCR7 can downregulate pathways critical for host anti-tumor immunity. In addition, mRNA expression of the lymphatic marker podoplanin was upregulated in CCR7-B16 tumors by 3.35-fold versus control tumors. Anti-podoplanin monoclonal antibody staining revealed a three-fold increase in intratumoral CCL21-expressing lymphatic vessels, as well as a two-fold increase in the number of invading tumor cells per lymphatic vessel in CCR7-B16 versus control tumors. Enhanced anti-vascular endothelial growth factor C (VEGF-C) staining was present in CCR7-B16 versus control tumors, suggesting that VEGF-C may have a role in the CCR7-mediated lymphangiogenesis. In summary, CCR7-B16 tumors show a striking decrease in IFN-γ-mediated inflammatory gene expression in contrast to increased expression of VEGF-C, CCL21 and podoplanin by lymphatic vessels. Enhanced lymphangiogenesis may contribute to the dramatic increase in LN metastasis that is observed in the CCR7-expressing tumors.
authors.affiliation: Department of Dermatology, Medical College of Wisconsin and Froedtert Hospital, Milwaukee, WI, USA.
authors.forename: T
authors.initials: T
authors.lastname: Takekoshi
authors.forename: L
authors.initials: L
authors.lastname: Fang
authors.forename: G
authors.initials: G
authors.lastname: Paragh
authors.forename: S T
authors.initials: ST
authors.lastname: Hwang
references.citation: Br J Cancer. 2004 Apr 5;90(7):1457-63
references.pmid: 15054471
references.citation: Nat Med. 2001 Feb;7(2):192-8
references.pmid: 11175850
references.citation: Genomics. 1994 Oct;23(3):643-50
references.pmid: 7851893
references.citation: J Natl Cancer Inst. 2001 Nov 7;93(21):1638-43
references.pmid: 11698568
references.citation: J Leukoc Biol. 2008 Oct;84(4):965-72
references.pmid: 18519742
references.citation: J Exp Med. 2001 Sep 17;194(6):797-808
references.pmid: 11560995
references.citation: J Cell Biol. 2006 Mar 27;172(7):973-81
references.pmid: 16567498
references.citation: Immunity. 1996 Aug;5(2):103-14
references.pmid: 8769474
references.citation: J Invest Dermatol. 2005 Sep;125(3):521-5
references.pmid: 16117793
references.citation: Clin Cancer Res. 2003 Dec 1;9(16 Pt 1):5962-7
references.pmid: 14676121
references.citation: Cell. 1992 Dec 24;71(7):1205-14
references.pmid: 1473153
references.citation: Cancer Res. 2009 Jan 1;69(1):349-57
references.pmid: 19118020
references.citation: Cancer Res. 2002 May 15;62(10):2937-41
references.pmid: 12019175
references.citation: J Clin Pathol. 2006 Feb;59(2):166-73
references.pmid: 16443733
references.citation: Oncogene. 2007 May 10;26(21):2997-3005
references.pmid: 17130836
references.citation: Eur J Clin Invest. 1988 Aug;18(4):343-51
references.pmid: 2458938
references.citation: Mod Pathol. 2005 Sep;18(9):1232-42
references.pmid: 15803182
references.citation: J Immunol. 1999 Mar 1;162(5):2472-5
references.pmid: 10072485
references.citation: J Leukoc Biol. 2006 Apr;79(4):639-51
references.pmid: 16478915
references.citation: Am J Pathol. 1999 Feb;154(2):385-94
references.pmid: 10027397
references.citation: Proc Natl Acad Sci U S A. 1998 Jan 6;95(1):258-63
references.pmid: 9419363
references.citation: Pigment Cell Melanoma Res. 2009 Apr;22(2):166-74
references.pmid: 19222803
references.citation: Am J Pathol. 2003 Jun;162(6):1951-60
references.pmid: 12759251