Transcriptional regulation of parathyroid hormone-related protein promoter P2 by NF-kappaB in adult T-cell leukemia/lymphoma.
Parathyroid hormone-related protein (PTHrP) plays a primary role in the development of humoral hypercalcemia of malignancy (HHM) that occurs in the majority of patients with adult T-cell leukemia/lymphoma (ATLL) due to human T-cell lymphotropic virus type-1 (HTLV-1) infection. We previously showed that ATLL cells constitutively express high levels of PTHrP via activation of promoters P2 and P3, resulting in HHM. In this study, we characterized a nuclear factor-kappaB (NF-kappaB) binding site in the P2 promoter of human PTHrP. Using electrophoretic mobility shift assays, we detected a specific complex in Tax-expressing human T cells composed of p50/c-Rel, and two distinct complexes in ATLL cells consisting of p50/p50 homodimers and a second unidentified protein(s). Chromatin immunoprecipitation assays confirmed in vivo binding of p50 and c-Rel on the PTHrP P2 promoter. Using transient co-transfection with NF-kappaB expression plasmids and PTHrP P2 luciferase reporter-plasmid, we showed that NF-kappaB p50/p50 alone and p50/c-Rel or p50/Bcl-3 cooperatively upregulated the PTHrP P2 promoter. Furthermore, inhibition of NF-kappaB activity by Bay 11-7082 reduced PTHrP P2 promoter-initiated transcripts in HTLV-1-infected T cells. In summary, the data demonstrated that transcriptional regulation of PTHrP in ATLL cells can be controlled by NF-kappaB activation and also suggest a Tax-independent mechanism of activation of PTHrP in ATLL.
Nadella
M V P
MV
Department of Veterinary Biosciences, The Ohio State University, Columbus, OH 43210, USA.
Dirksen
W P
WP
Nadella
K S
KS
Shu
S
S
Cheng
A S
AS
Morgenstern
J A
JA
Richard
V
V
Fernandez
S A
SA
Huang
T H
TH
Guttridge
D
D
Rosol
T J
TJ
D000328:Adult; D000818:Animals; D015153:Blotting, Western; D045744:Cell Line, Tumor; D015500:Chloramphenicol O-Acetyltransferase; D047369:Chromatin Immunoprecipitation; D024202:Electrophoretic Mobility Shift Assay; D015972:Gene Expression Regulation, Neoplastic; D015490:HTLV-I Infections / Q000378:metabolism / Q000821:virology; D006801:Humans; D015459:Leukemia-Lymphoma, Adult T-Cell / Q000235:genetics* / Q000378:metabolism / Q000473:pathology; D051379:Mice; D016688:Mice, Inbred NOD; D016513:Mice, SCID; D016297:Mutagenesis, Site-Directed; D016328:NF-kappa B / Q000502:physiology*; D044162:Parathyroid Hormone-Related Protein / Q000235:genetics* / Q000378:metabolism; D010957:Plasmids; D016133:Polymerase Chain Reaction; D011401:Promoter Regions, Genetic; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015533:Transcriptional Activation; D014162:Transfection
D016328:NF-kappa B; D044162:Parathyroid Hormone-Related Protein; D012333:RNA, Messenger; D015500:Chloramphenicol O-Acetyltransferase