Regulation of an H-ras-related transcript by parathyroid hormone in rat osteosarcoma cells.
The rat osteosarcoma cell line UMR 106-01 is a commonly used model system for the study of osteoblast function. However, it also expresses a phenotype characteristic of transformed cells. To test whether the latter could be accounted for by aberrant oncogene expression, we probed Northern blots of UMR and other osteoblastic cells with a panel of oncogene probes. These blots, when probed with a cDNA specific for v-H-ras, revealed a 7.0-kilobase (kb) H-ras-related transcript (designated HRRT) in UMR 106-01 cells that was not expressed in other osteoblastic cells. Osteoblast-enriched calvarial cells expressed the typical 1.1-kb H-ras mRNA, which was absent in UMR cells. Additionally, Western blots of lysates of UMR cells documented the presence of three proteins immunologically related to H-rasp21. To determine whether HRRT represented a recombinant retrovirus product, Northern blots were probed with a cDNA specific for the highly conserved gag-pol region of Moloney murine leukemia virus. These blots showed parallel cross-reactivity with an apparently identical transcript of 7.0 kb. The 7.0-kb transcripts detected by both v-H-ras and gag-pol probes declined to the same extent after treatment with concentrations of PTH known to inhibit proliferation of these cells. PTH regulated the abundance of HRRT in a time- and dose-dependent manner, with greatest repression of the transcript after 8 h of treatment with 10(-8) M PTH. The decrease in HRRT could not be completely accounted for by changes in transcriptional activity, as determined by nuclear run-on assays.(ABSTRACT TRUNCATED AT 250 WORDS)
Pediatric Research Institute, Cardinal Glennon Children's Hospital, St. Louis University School of Medicine, Missouri 63110.
D K
DK
Scott
W R
WR
Weaver
J C
JC
Clohisy
K D
KD
Brakenhoff
A J
AJ
Kahn
N C
NC
Partridge
D000818:Animals; D015152:Blotting, Northern; D001859:Bone Neoplasms / Q000235:genetics / Q000378:metabolism* / Q000382:microbiology; D002471:Cell Transformation, Neoplastic / Q000235:genetics*; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects*; D015967:Gene Expression Regulation, Viral / Q000187:drug effects; D011905:Genes, ras; D009363:Neoplasm Proteins / Q000096:biosynthesis* / Q000235:genetics; D015689:Oncogene Protein p21(ras) / Q000096:biosynthesis* / Q000235:genetics; D010006:Osteoblasts / Q000187:drug effects* / Q000378:metabolism; D012516:Osteosarcoma / Q000235:genetics / Q000378:metabolism* / Q000382:microbiology; D010281:Parathyroid Hormone / Q000494:pharmacology*; D011061:Poly A / Q000235:genetics; D011533:Proviruses / Q000235:genetics*; D012333:RNA, Messenger / Q000235:genetics; D012334:RNA, Neoplasm / Q000235:genetics; D051381:Rats; D012190:Retroviridae / Q000235:genetics*; D012886:Skull / Q000166:cytology; D014407:Tumor Cells, Cultured
D009363:Neoplasm Proteins; D010281:Parathyroid Hormone; D012333:RNA, Messenger; D012334:RNA, Neoplasm; D011061:Poly A; D015689:Oncogene Protein p21(ras)