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Background. Continuous local delivery of interleukin-2 (IL-2) and interferon-alpha (IFN-[alpha]) via gene transfer appears to be more effective than systemic therapy in preventing the growth of human renal cell carcinoma (RCC) in vitro and in vivo. To understand further if cytokine-gene transfection of RCC could alter certain cellular properties that are associated with the invasive and metastatic potentials of tumor, the authors characterized six cell lines that produce IL-2 and/or IFN-[alpha] in their expression of intercellular adhesion molecule-1 (ICAM-1) and CD44; binding affinity to extracellular matrix (ECM) components (fibronectin, laminin, type IV collagen, and vitronectin); and preference in forming homotypic aggregation and mRNA levels of c-myc, epidermal growth factor receptor (EGF-R), tumor transforming growth factor-[beta] (TGF-[beta] and type IV collagenase. These six lines were compared with control vector transfected parental R11 line. Methods. The expression of ICAM-1 and CD44 was determined by fluorescence-activated cell sorter (FACS) analysis, the tumor cell binding affinity to ECM components was measured by cell attachment assay, the degree of homotypic aggregation was quantified by cell aggregation assay, and the mRNA levels of c-myc, EGF-R, TGF-[beta], and collagenase were analyzed by a quantitative polymerase chain reaction analysis. Results. Both IL-2-gene- and IFN-[alpha]-gene-modified R11 exhibited enhanced expression of ICAM-1, suppression of CD44, and decreased binding affinity to ECM components, when compared with the R11-control vector. All cytokine-producing tumor lines showed a decreased preference to form homotypic aggregation. Interferon-alpha gene transfer downregulated c-myc, EGF-R, and type IV collagenase mRNA expression, whereas only the higher producers of IL-2 downregulated TGF-[beta] mRNA expression. Exogenous IL-2 and/or IFN-[alpha] treatment of a IFN-[alpha]-resistant RCC enhanced both HLA class I antigen and ICAM-1 expression and suppressed CD44 expression, but had no effect on tumor growth rate. Conclusions. The local production of high concentrations of IL-2 and IFN-a at the tumor site may directly alter tumor properties associated with invasive and metastatic phenotypes of RCC. Interleukin-2 and/or IFN-[alpha] gene therapy may be an effective strategy for treatment of patients with advanced renal cancer. Cancer 1994; 74:1904-11.

Background: Combination therapy with systemically administered interleukin-2 (IL-2) and interferon [Alpha] (IFN-[Alpha]) has resulted in long-term objective remissions in 30% of patients with metastatic renal cell carcinoma (RCC), but toxic effects are clinically significant. Purpose: We have thus investigated an alternative therapeutic approach--continuous intratumoral production of IL-2 and/or IFN-[Alpha] by a cytokine-transfected human RCC tumor cell line. Methods: Plasmid vectors were used to transfect the R11 RCC line with the genes for human IL-2 and/or IFN-[Alpha] by the calcium phosphate precipitation method. Biologic characteristics of the cytokine-transfected tumor cells were determined by assays of thymidine incorporation and cytotoxicity, fluorescence-activated cell-sorter analysis, Northern blotting, and in vivo studies in C3Hf/Sed/Kam mice rendered T-cell deficient. Results: The transfected cell lines produced the following amounts of cytokine per [10.sup.6] cells per day: R11-IL-2 (220 U), R11-IFN-[Alpha] (10240 U), and R11-IL-2 + IFN-[Alpha] (95 U + 1270 U, respectively). Gamma irradiation did not eliminate cytokine secretion. Morphology and growth rates were identical to those for the parental R11 cell line, except for IFN-[Alpha]-producing clones, which showed significant growth inhibition. All cytokine-producing cells demonstrated increased susceptibility to cell killing by peripheral blood leukocytes (PBL). IFN-[Alpha] producers exhibited enhanced HLA antigen expression and suppressed c-myc messenger RNA expression; when cocultured in vitro, they induced similar changes in parental R11 cells. IL-2 producers could stimulate growth and cytotoxicity of naive (i.e., freshly isolated, uncultured) and activated PBL. All cytokine-producing cells lost their tumorigenicity, as evidenced by failure to grow in the T-cell-depleted mice. When co-injected at a local site but not at a distant site, these cells prevented growth of parental R11 cells. Histologic examination of the injection sites revealed a substantial influx of macrophages. Intraperitoneal administration of IL-2 and/ or IFN-[Alpha] could not, however, prevent growth of the parental R11 tumors. Conclusion: Local production of high concentrations of IL-2 and IFN-[Alpha] at the tumor site is more effective in preventing tumor growth than systemic administration. Implication: Continuous local delivery of cytokines via transfer of cytokine genes into tumor cells for use as live cancer vaccines is a novel strategy for manipulation of host-mediated antitumor immune response in patients with advanced RCC. [J Natl Cancer Inst 85:207-216, 1993]