1,25-Dihydroxyvitamin D3 increases the cellular content of the calcium-activated neutral protease mu-calpain in renal cell carcinoma.
mu-Calpain is a calcium-dependent neutral thiol protease activated by micromolar concentrations of calcium. mu-Calpain is implicated in various cellular functions regulated by calcium including exocytosis, cell fusion, apoptosis and control of cell proliferation. We studied the effect of 1,25-(OH)2D3 on mu-calpain levels in the human renal cell carcinoma line SK-RC-29 using monoclonal antibodies to the 80 kDa subunit of mu-calpain. Exposure of low density cultures (15000 cells/cm2) to 1,25-(OH)2D3 (100nM) for 48 hours resulted in 1.5-3 fold increase of mu-calpain cell content. The effect was not observed in higher density cultures (40000 cells/cm2). mu-Calpain content of high density cultures was higher than that of low density cultures and similar to that in low density cultures treated by 1,25-(OH)2D3. The cellular content of two other calcium binding proteins, annexin II and annexin VI was not affected by the hormone. 1,25-(OH)2D3 did not affect cell number or viability therefore its effect on mu-calpain is not secondary to changes in cell density. The effect of 1,25-(OH)2D3 was dose-dependent apparent already at 1nM and was not observed with 24,25-(OH)2D3. Increase in mu-calpain content may underlie some of the actions of 1,25-(OH)2D3 on classical and non classical target cells.
Ravid
A
A
Basil and Gerald Felsenstein Medical Research Center, Beilinson Campus, Petah Tikva, Israel.
Koren
R
R
Rotem
C
C
Garach-Jehoshua
O
O
Glaser
T
T
Liberman
U A
UA
D002117:Calcitriol / Q000494:pharmacology*; D002154:Calpain / Q000378:metabolism*; D002292:Carcinoma, Renal Cell / Q000378:metabolism* / Q000473:pathology; D002452:Cell Count; D003720:Densitometry; D004305:Dose-Response Relationship, Drug; D004591:Electrophoresis, Polyacrylamide Gel; D006801:Humans; D015151:Immunoblotting; D007680:Kidney Neoplasms / Q000378:metabolism* / Q000473:pathology; D014407:Tumor Cells, Cultured
D002154:Calpain; D002117:Calcitriol