| Abstract |
Certain osteoclastic markers (multinucleation and tartrate-resistant acid phosphatase) were induced in human leukemia HL-60 cells by treatment with 10(-7) M 1,25-dihydroxy-vitamin D3 [1,25(OH)2D3] for 10 days. However, no formation of pits on a bone substrate by vitamin-treated HL-60 cells was detected. Expression of calcitonin receptors (CTR), another osteoclastic marker, was examined by means of the reverse transcriptase polymerase chain reaction. The human CTR-cDNA (T47D isotype) was amplified from untreated HL-60 cells, but not from cells treated with 1,25(OH)2D3. The CTR mRNA disappeared within 24 h after the treatment. Thus, 1,25(OH)2D3-differentiated HL-60 cells failed to show two intrinsic characteristics of osteoclasts, pit formation on a bone substrate and expression of CTR. We then examined the expression of CTR on established human leukemia cell lines. The CTR mRNA was expressed in myeloblastic ML-1 and promyelocytic HL-60 leukemia cells but not in more mature macrophage-like cell lines, U-937 and THP-1 cells. Neither B cell leukemia BALL-1, T cell leukemia Jurkat, promegakaryoblastic leukemia Meg-J, nor cervix uteri carcinoma HeLa S3 cells amplified the CTR products. The cDNA of BIN67-isotype CTR, that has an additional 16-amino acid insert in the putative first intracellular loop of T47D-type CTR [Kuestner et al. (1994) Mol. Pharmacol. 46, 246-255], was amplified by neither strain tested. It was suggested that the T47D-type CTR is a novel differentiation antigen of immature myeloid lineage cells.
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