Interleukin-2 expression in human carcinoma cell lines and its role in cell cycle progression.
Human carcinomas were shown to express mRNA and protein for IL-2R alpha, beta and gamma chains. Recently, human carcinomas were also shown to constitutively express protein and mRNA for IL-2 in vivo and in vitro. Here we report that the expression levels of cytoplasmic IL-2 as well as IL-2Rbeta- and gamma-chain in human carcinoma cells change during the cell cycle progression. Carcinoma cells synchronized in the G2/M phase of the cell cycle expressed significantly more intracytoplasmic IL-2 as well as IL-2Rbeta and gamma proteins than tumor cells in the G0/G1 phase. The level of mRNA for IL-2 was 5-10-fold higher in the M phase than in the G0/G1-phase, as shown by quantitative competitive RT-PCR. Expression of the cyclin-dependent kinase (CDK) inhibitor p27kip1 in these carcinoma cells was found to be high in the G0/G1 phase, nearly absent in the S phase, and it increased again in the G2/M phase of the cell cycle. In synchronized cells, the decrease in p27 expression coincided with high levels of expression of IL-2. Using the IL-2 specific antisense oligonucleotide to block synthesis of endogenous IL-2 in tumor cells, we observed increased levels of p27 as well as p21. The antisense oligonucleotides specific for p27 or p21 blocked expression of these proteins but not of IL-2. Thus, endogenous IL-2 is important in regulating expression of p27 as well as p21 and, therefore, in controlling cell cycle progression of tumor cells, while its own expression remains independent of the CDK inhibitors.
Reichert
T E
TE
University of Pittsburgh Cancer Institute, University of Pittsburgh School of Medicine, 15213, USA.
Nagashima
S
S
Kashii
Y
Y
Stanson
J
J
Gao
G
G
Dou
Q P
QP
Whiteside
T L
TL
D015153:Blotting, Western; D002277:Carcinoma / Q000235:genetics / Q000473:pathology*; D002453:Cell Cycle / Q000235:genetics*; D018797:Cell Cycle Proteins; D002478:Cells, Cultured; D050759:Cyclin-Dependent Kinase Inhibitor p21; D050760:Cyclin-Dependent Kinase Inhibitor p27; D016213:Cyclins / Q000096:biosynthesis / Q000235:genetics; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects; D006801:Humans; D007124:Immunoenzyme Techniques; D007376:Interleukin-2 / Q000096:biosynthesis* / Q000235:genetics / Q000502:physiology; D019169:Jurkat Cells / Q000378:metabolism / Q000473:pathology; D015603:Keratinocytes / Q000166:cytology / Q000378:metabolism; D008869:Microtubule-Associated Proteins / Q000096:biosynthesis / Q000235:genetics; D009363:Neoplasm Proteins / Q000096:biosynthesis* / Q000235:genetics / Q000502:physiology; D016376:Oligonucleotides, Antisense / Q000494:pharmacology; D012333:RNA, Messenger / Q000096:biosynthesis; D012334:RNA, Neoplasm / Q000096:biosynthesis; D015375:Receptors, Interleukin-2 / Q000096:biosynthesis* / Q000235:genetics / Q000502:physiology; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013601:T-Lymphocytes / Q000166:cytology / Q000378:metabolism; D014407:Tumor Cells, Cultured; D025521:Tumor Suppressor Proteins
C493956:CDKN1A protein, human; D018797:Cell Cycle Proteins; D050759:Cyclin-Dependent Kinase Inhibitor p21; D016213:Cyclins; D007376:Interleukin-2; D008869:Microtubule-Associated Proteins; D009363:Neoplasm Proteins; D016376:Oligonucleotides, Antisense; D012333:RNA, Messenger; D012334:RNA, Neoplasm; D015375:Receptors, Interleukin-2; D025521:Tumor Suppressor Proteins; D050760:Cyclin-Dependent Kinase Inhibitor p27