rIFN-γ-mediated growth suppression of platinum-sensitive and -resistant ovarian tumor cell lines not dependent upon arginase inhibition

BACKGROUND: Arginine metabolism in tumor cell lines can be influenced by various cytokines, including recombinant human interferon-γ (rIFN-γ), a cytokine that shows promising clinical activity in epithelial ovarian cancer (EOC). METHODS: We examined EOC cell lines for the expression of arginase in an enzymatic assay and for transcripts of arginase I and II, inducible nitric oxide synthase (iNOS), and indoleamine 2,3-dioxygenase (IDO) by reverse transcription-polymerase chain reaction. The effects of rIFN-γ on arginase activity and on tumor cell growth inhibition were determined by measuring [(3)H]thymidine uptake. RESULTS: Elevated arginase activity was detected in 5 of 8 tumor cell lines, and analysis at the transcriptional level showed that arginase II was involved but arginase I was not. rIFN-γ reduced arginase activity in 3 EOC cell lines but increased activity in the 2008 cell line and its platinum-resistant subline, 2008.C13. iNOS transcripts were not detected in rIFN-γ-treated or untreated cell lines. In contrast, IDO activity was induced or increased by rIFN-γ. Suppression of arginase activity by rIFN-γ in certain cell lines suggested that such inhibition might contribute to its antiproliferative effects. However, supplementation of the medium with polyamine pathway products did not interfere with the growth-inhibitory effects of rIFN-γ EOC cells. CONCLUSIONS: Increased arginase activity, specifically identified with arginase II, is present in most of the tested EOC cell lines. rIFN-γ inhibits or stimulates arginase activity in certain EOC cell lines, though the decrease in arginase activity does not appear to be associated with the in vitro antiproliferative activity of rIFN-γ. Since cells within the stroma of EOC tissues could also contribute to arginine metabolism following treatment with rIFN-γ or rIFN-γ-inducers, it would be helpful to examine these effects in vivo

Cytokines, GM-CSF and IFNγ administered by priming and post-chemotherapy cycling in recurrent ovarian cancer patients receiving carboplatin

BACKGROUND: Monocyte/macrophages (MO/MA), a polymorphic population of innate immune cells, have the potential to mediate antitumor effects, and may also contribute to protumor effects. A priming and post-chemotherapy schedule of the myeloid cell mobilizing and immune stimulatory growth factor, granulocyte monocyte stimulating factor (GM-CSF, Leukine(®)) and the MO/MA activating cytokine recombinant interferon gamma 1b (rIFN-γ1b, Actimmune(®)) has been developed. The pre- and post-chemotherapy design is based upon known in vivo kinetics and immune modulatory effects of these molecules. Carboplatin (Paraplatin(®)) was selected as the cornerstone of treatment of epithelial ovarian cancer (EOC). METHODS: We studied hematopoietic and immunologic effects of GM-CSF and rIFN-γ1b before and after carboplatin in patients with recurrent EOC. Potentially chemotherapy-sensitive patients with recurrent measurable tumors received subcutaneous GM-CSF (starting at 400 μg/day) for 7 days plus subcutaneous rIFN-γ1b (100 μg) on days 5 and 7, before and after intravenous carboplatin (area under the curve of 5). We performed standard hematologic assessment and monitored monocyte (MO), dendritic cell, major cell subset counts, and antibody-dependent cell-mediated cytotoxicity (ADCC) against a Her2neu(+ )tumor cell line, as well as selected plasma inflammatory cytokine, chemokine and growth factor levels. RESULTS: Our analysis comprised only the first 3 months of treatment in the initial 25 patients. Relative to pretreatment baseline values, white blood cell, neutrophil, MO, and eosinophil counts increased (P ≤ .001 for each); the proportion of platelets increased 9 days after the second (P ≤ .002) and third (P ≤ .04) carboplatin treatments; and the number of cells in the activated MO subsets CD14+HLA-DR+, CD14+CD64+, and CD14(+)CXCR3(+ )increased (P ≤ .04 for each); plasma levels of the proangiogenic interleukins 1α, 6, and 8 were lower (P ≤ .03 for each); M-CSF, a product of activated MO/MA, was increased on day 9 (P = .007); and GM-CSF was increased in plasma after GM-CSF administration (P ≤ .04). Quality of life measurements were reduced during the GM-CSF/IFN-γ1b cycle while recovering at pre-chemotherapy baseline for FACT-G scores only. CONCLUSION: A novel regimen of GM-CSF plus IFN-γ1b administered to 25 EOC patients receiving carboplatin increased myeloid cells, platelets and total activated MO populations during the initial 3 months; however, ADCC responses were not consistently enhanced during this period

rIFN-gamma-mediated growth suppression of platinum-sensitive and -resistant ovarian tumor cell lines not dependent upon arginase inhibition.

BACKGROUND: Arginine metabolism in tumor cell lines can be influenced by various cytokines, including recombinant human interferon-gamma (rIFN-gamma), a cytokine that shows promising clinical activity in epithelial ovarian cancer (EOC). METHODS: We examined EOC cell lines for the expression of arginase in an enzymatic assay and for transcripts of arginase I and II, inducible nitric oxide synthase (iNOS), and indoleamine 2,3-dioxygenase (IDO) by reverse transcription-polymerase chain reaction. The effects of rIFN-gamma on arginase activity and on tumor cell growth inhibition were determined by measuring [3H]thymidine uptake. RESULTS: Elevated arginase activity was detected in 5 of 8 tumor cell lines, and analysis at the transcriptional level showed that arginase II was involved but arginase I was not. rIFN-gamma reduced arginase activity in 3 EOC cell lines but increased activity in the 2008 cell line and its platinum-resistant subline, 2008.C13. iNOS transcripts were not detected in rIFN-gamma-treated or untreated cell lines. In contrast, IDO activity was induced or increased by rIFN-gamma. Suppression of arginase activity by rIFN-gamma in certain cell lines suggested that such inhibition might contribute to its antiproliferative effects. However, supplementation of the medium with polyamine pathway products did not interfere with the growth-inhibitory effects of rIFN-gamma EOC cells. CONCLUSIONS: Increased arginase activity, specifically identified with arginase II, is present in most of the tested EOC cell lines. rIFN-gamma inhibits or stimulates arginase activity in certain EOC cell lines, though the decrease in arginase activity does not appear to be associated with the in vitro antiproliferative activity of rIFN-gamma. Since cells within the stroma of EOC tissues could also contribute to arginine metabolism following treatment with rIFN-gamma or rIFN-gamma-inducers, it would be helpful to examine these effects in vivo