IFN-alpha-2b-induced signal transduction and gene regulation in patient peripheral blood mononuclear cells is not enhanced by a dose increase from 5 to 10 megaunits/m2.
OBJECTIVE
The precise molecular targets of IFN-alpha therapy of melanoma are unknown but likely involve signal transducer and activator of transcription (STAT) 1 signal transduction within host immune effector cells. We hypothesized that intermediate and high doses of IFN-alpha would be equally effective in activating patient immune cells.


METHODS
Eleven metastatic melanoma patients who were enrolled in a clinical trial of bevacizumab in combination with escalating doses of IFN-alpha-2b (5 megaunits/m(2) and then 10 megaunits/m(2)) were included in the study. Peripheral blood mononuclear cells (PBMC) were procured from patient blood just before therapy and again 1 h after each dose of IFN-alpha-2b and analyzed for the presence of phosphorylated STAT1, phosphorylated STAT2, and the induction of IFN-stimulated gene (ISG) transcripts.


RESULTS
Phosphorylated STAT1 was significantly greater at the 5 megaunits/m(2) dose compared with the 10 megaunits/m(2) dose of IFN-alpha-2b (P = 0.02). In contrast, no significant difference in phosphorylated STAT2 was observed at a dose of 5 megaunits/m(2) compared with 10 megaunits/m(2) (P = 0.20). There were also no significant differences in the induction of ISGs within PBMCs between the two doses (P > 0.4 for all ISGs). Suppressor of cytokine signaling 1 and 3 (two inhibitors of IFN-alpha signaling) transcripts were significantly higher among patient PBMCs following the 10 megaunits/m(2) dose of IFN-alpha (P < 0.001).


CONCLUSIONS
These results suggest that lower doses of IFN-alpha-2b are as effective as higher doses with respect to the induction of Janus-activated kinase-STAT signal transduction and the transcription of ISGs within immune effector cells.
Zimmerer
Jason M
JM
Integrated Biological Sciences Graduate Program, The Ohio State University, Columbus, Ohio 43210, USA.
Lehman
Amy M
AM
Ruppert
Amy S
AS
Noble
Carl W
CW
Olencki
Thomas
T
Walker
Michael J
MJ
Kendra
Kari
K
Carson
William E
WE
D000328:Adult; D000368:Aged; D000911:Antibodies, Monoclonal / Q000008:administration & dosage; D061067:Antibodies, Monoclonal, Humanized; D000971:Antineoplastic Combined Chemotherapy Protocols / Q000008:administration & dosage*; D000068258:Bevacizumab; D014408:Biomarkers, Tumor / Q000235:genetics / Q000378:metabolism; D005260:Female; D005434:Flow Cytometry; D020869:Gene Expression Profiling; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects*; D006801:Humans; D000077190:Interferon alpha-2; D016898:Interferon-alpha / Q000008:administration & dosage*; D008113:Liver Neoplasms / Q000188:drug therapy / Q000556:secondary; D008175:Lung Neoplasms / Q000188:drug therapy / Q000556:secondary; D008207:Lymphatic Metastasis; D008297:Male; D008545:Melanoma / Q000188:drug therapy* / Q000276:immunology / Q000473:pathology; D008875:Middle Aged; D020411:Oligonucleotide Array Sequence Analysis; D010766:Phosphorylation / Q000187:drug effects; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D011994:Recombinant Proteins; D020133:Reverse Transcriptase Polymerase Chain Reaction; D050794:STAT1 Transcription Factor / Q000378:metabolism; D050795:STAT2 Transcription Factor / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects*
D000911:Antibodies, Monoclonal; D061067:Antibodies, Monoclonal, Humanized; D014408:Biomarkers, Tumor; D000077190:Interferon alpha-2; D016898:Interferon-alpha; D012333:RNA, Messenger; D011994:Recombinant Proteins; D050794:STAT1 Transcription Factor; C494079:STAT1 protein, human; D050795:STAT2 Transcription Factor; D000068258:Bevacizumab