The role of interleukin 1 in growth and metastasis of human cancer xenografts.
BACKGROUND
Interleukin 1 (IL-1) is a pluripotent cytokine that promotes angiogenesis, tumor growth, and metastasis in experimental models; its presence in some human cancers is associated with aggressive tumor biology. The purpose of these studies was to characterize the role of IL-1 in human cancers and determine if inhibition of IL-1 via its receptor antagonist, IL-1Ra, alters tumor growth and metastatic potential.


METHODS
IL-1 mRNA or protein levels were determined in clinical tumor samples, cancer cell lines, and xenografts using quantitative reverse transcription-PCR or ELISA. Biological activity of tumor-derived IL-1 protein was shown via induction of permeability across endothelial cell monolayers. The effects of recombinant IL-1Ra on tumor lines in culture (cell proliferation and IL-8 secretion) and in xenograft models (tumor growth, metastatic potential, and intratumoral levels of IL-8 and VEGF) were characterized. The effects of IL-1Ra-mediated regression of xenograft growth on angiogenic proteins (IL-8 and VEGF) were evaluated in an IL-1-producing melanoma (SMEL) xenograft model.


RESULTS
IL-1 mRNA was highly expressed in more than half of all tested metastatic human tumor specimens including non-small-cell lung carcinoma, colorectal adenocarcinoma, and melanoma tumor samples. Constitutive IL-1 mRNA expression was identified in several cancer cell lines; tumor supernatant from these cell lines produced a significant increase in endothelial cell monolayer permeability, a hallmark event in early angiogenesis, in an IL-1-dependent manner. Moreover, systemic recombinant IL-1Ra resulted in significant inhibition of xenograft growth and neovessel density of IL-1-producing, but not non-IL-1-producing, tumor cell lines. Subsequent analysis of SMEL, a melanoma cell line with constitutive IL-1 production, showed that neither exogenous IL-1 nor IL-1Ra altered tumor cell proliferation rates in vitro. Gene expression analyses of IL-1Ra-treated SMEL xenografts showed a >3-fold down-regulation of 100 genes compared with control including a marked down-regulation of IL-8 and VEGF.


CONCLUSIONS
These data show that the IL-1 gene is frequently expressed in metastases from patients with several types of human cancers. IL-1Ra inhibits xenograft growth in IL-1-producing tumors but has no direct antiproliferative effects in vitro; decreased tumor levels of IL-8 and VEGF may be an early surrogate of IL-1Ra-mediated antitumor activity. IL-1Ra may have a role alone or with other agents in the treatment of human cancers.
Elaraj
Dina M
DM
Surgical Metabolism Section, Surgery Branch, Center for Cancer Research, National Cancer Institute, Bethesda, Maryland 20892-1201, USA.
Weinreich
David M
DM
Varghese
Sheelu
S
Puhlmann
Markus
M
Hewitt
Stephen M
SM
Carroll
Nancy M
NM
Feldman
Elizabeth D
ED
Turner
Ewa M
EM
Alexander
H Richard
HR
D000818:Animals; D045744:Cell Line, Tumor; D002463:Cell Membrane Permeability / Q000187:drug effects; D049109:Cell Proliferation / Q000187:drug effects; D002478:Cells, Cultured; D004305:Dose-Response Relationship, Drug; D042783:Endothelial Cells / Q000187:drug effects / Q000502:physiology; D005260:Female; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D053590:Interleukin 1 Receptor Antagonist Protein; D007375:Interleukin-1 / Q000235:genetics* / Q000494:pharmacology / Q000502:physiology; D016209:Interleukin-8 / Q000096:biosynthesis; D008546:Melanoma, Experimental / Q000188:drug therapy / Q000235:genetics* / Q000378:metabolism; D051379:Mice; D008819:Mice, Nude; D009362:Neoplasm Metastasis / Q000517:prevention & control; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012795:Sialoglycoproteins / Q000378:metabolism / Q000494:pharmacology; D013997:Time Factors; D042461:Vascular Endothelial Growth Factor A / Q000096:biosynthesis; D023041:Xenograft Model Antitumor Assays
C507763:IL1RN protein, human; C507764:Il1rn protein, mouse; D053590:Interleukin 1 Receptor Antagonist Protein; D007375:Interleukin-1; D016209:Interleukin-8; D012333:RNA, Messenger; D012795:Sialoglycoproteins; D042461:Vascular Endothelial Growth Factor A