The role of endogenous interleukin-2 in proliferation of human carcinoma cell lines

Abstract

Summary Interleukin (IL-2) and IL-2Rβ/γ have been shown to be expressed in human carcinomas in culture and in situ. Recently, expression of endogenous IL-2 and IL-2R in the cytoplasm was found to be up-regulated in tumour cells undergoing mitosis. This observation suggested that similar to its role in lymphocytes, the IL-2/IL-R pathway is involved in the regulation of carcinoma cell proliferation. Metabolic labelling followed by immunoprecipitation and Western blot results showed that IL-2 in carcinomas was identical to that in human lymphocytes. However, tumour cells did not secrete IL-2 detectable by immunoassays, although membrane-associated IL-2 was detectable on a proportion of these cells cultured in the absence of exogenous IL-2. Antibodies to IL-2 failed to inhibit proliferation of carcinoma cells, but antibodies specific for the ligand-binding site of the IL-2R were growth inhibitory. Growth of tumour cells was also inhibited by the immunosuppressive drugs, cyclosporin A (CsA), FK506 and rapamycin (RPA), known to interfere with the IL-2 pathway in lymphocytes. To further confirm the role of endogenous IL-2 in the growth of carcinomas, tumour cells were incubated with an IL-2-specific antisense oligonucleotide. The treatment was shown to transiently inhibit IL-2 mRNA and IL-2 protein expression as well as proliferation of tumour cells. Tumour cells treated with IL-2-specific antisense oligonucleotide demonstrated increased apoptosis in comparison to untreated or sense oligonucleotide-treated control cells. The data indicate that in human carcinomas, endogenous IL-2 promotes growth and protects tumour cells from apoptosis.

Interleukin-2 expression in human carcinoma cell lines and its role in cell cycle progression

“…However, exogenous IL-2 used at therapeutic doses was found to inhibit carcinoma growth in vitro and in vivo in nude mice (Weidmann et al, 1992;Rabinowich et al, 1992). The opposite biologic e ects of endogenous vs exogenous IL-2 described by us earlier (Reichert et al, 1999) emphasize the complexity of interactions between autocrine and exocrine IL-2 pathways.…”

“…The IL-2/IL-2R pathway in human carcinoma TE Reichert et al growth (Table 2), under conditions described earlier (Reichert et al, 1999). While this strategy indicated that inhibition of endogenous IL-2 resulted in the upregulation of both p27 and p21 CDK inhibitor levels (Figure 8), it also suggested the existence of complex regulatory mechanisms involving this endogenous cytokine IL-2.…”

“…Oligonucleotides (sense and antisense) were selected in the 5' coding region of hIL-2, phosphorothioated and chromatographically puri®ed and used as described by us earlier (Reichert et al, 1999). Brie¯y, tumor cells maintained in media with reduced serum concentration (1%) were plated at the concentration of 5610 3 cells per well in wells of a 96-well plate and treated with sense (SO) or antisense (ASO) oligonucleotides, mixed with a cationic lipid transfection reagent N-[1-(2,3 Dioleoyloxy) propyl](-N,N,N-trimethyl ammonium methylsulfate (DOTAP, Boehringer Mannheim, Indianapolis, IN, USA) at the ®nal concentration of 5 ml DOTAP/1 mg oligonucleotide for 24 ± 48 h. The cells were then washed and examined for growth inhibition in MTT assays.…”

Interleukin-2 and its receptor complex (α, β and γ chains) in in situand infiltrative human breast cancer: an immunohistochemical comparative study

“…Experimental studies of squamous cell carcinomas of head and neck have shown that antisense IL-2 treatment or blocking of IL-2Rβ results in growth inhibition [12]. …”

Detection of cancer cells and gene expression of cytokines in the peritoneal cavity in patients with gastric cancer

“…Recently, a contrary finding on IL-2 function was reported, in which endogenous IL-2 promoted tumor cells growth and protected these cells from apoptosis [18]. Thus, the role of cytokines produced by cells in the peritoneal cavity in tumor growth in gastric cancer patients is still unclear.…”