IL-4 inhibits the TNF-alpha induced proliferation of renal cell carcinoma (RCC) and cooperates with TNF-alpha to induce apoptotic and cytokine responses by RCC: implications for antitumor immune responses.
OBJECTIVE
While previous reports clearly demonstrated antiproliferative effects of IL-4 on renal cell carcinoma (RCC) in vitro, the administration of IL-4 to patients with metastatic RCC in clinical trials could not recapitulate the promising preclinical results. In the present study we wanted to examine the context of IL-4 action and to establish conditions of enhanced IL-4 efficacy.


METHODS
Primary and permanent human RCC cells were cultured in either serum-supplemented or chemically defined, serum-free culture medium in the presence or absence of cytokines. Cell proliferation was assessed as [(3)H]-thymidine incorporation. Cell apoptosis was measured using the fluorescent DNA intercalator 7-aminoactinomycin D and flow cytometry. In addition, culture media conditioned by RCC were subjected to cytokine antibody array and cytokine multiplex analysis.


RESULTS
Our results indicate that the previously reported antiproliferative effects of IL-4 are serum-dependent. Under serum-free conditions, IL-4 failed to exhibit growth-inhibitory effects or was even growth-stimulatory. In a chemically defined, serum-free medium (AIM-V), however, IL-4 inhibited the TNF-alpha induced proliferation of RCC. IL-4 and TNF-alpha synergistically induced apoptosis of RCC as well as a complex cytokine response by RCC, which included the synergistic upregulation of RANTES and MCP-1.


CONCLUSIONS
IL-4 alone has little effect on the spontaneous proliferation of RCC but can prevent the enhancement of proliferation induced by growth promoters like FBS and TNF-alpha. The concomitant growth inhibitory, apoptosis-inducing, and cytokine-enhancing effects of IL-4 in combination with TNF-alpha on RCC support the view that Th2 cytokines may be required for productive immune responses against RCC.
Falkensammer
Claudia
C
Department of Urology kompetenzzentrum medizin tirol (kmt), Medical University of Innsbruck, Anichstrasse 35, 6020 Innsbruck, Austria.
Jöhrer
Karin
K
Gander
Hubert
H
Ramoner
Reinhold
R
Putz
Thomas
T
Rahm
Andrea
A
Greil
Richard
R
Bartsch
Georg
G
Thurnher
Martin
M
D017209:Apoptosis / Q000187:drug effects* / Q000276:immunology; D002292:Carcinoma, Renal Cell / Q000276:immunology*; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects*; D016207:Cytokines / Q000187:drug effects / Q000276:immunology; D005434:Flow Cytometry; D006801:Humans; D015847:Interleukin-4 / Q000276:immunology / Q000494:pharmacology*; D007680:Kidney Neoplasms / Q000276:immunology*; D014409:Tumor Necrosis Factor-alpha / Q000276:immunology*
D016207:Cytokines; D014409:Tumor Necrosis Factor-alpha; D015847:Interleukin-4