Effects of bradykinin on cytoplasmic calcium and motility in murine bladder tumor cells.
OBJECTIVE
Bradykinin is known to mobilize calcium from an intracellular or extracellular source in several tumor cells. We evaluated whether bradykinin increases cytoplasmic calcium concentration ([Ca2+]i) and evokes locomotory movement in bladder cancer cells.


METHODS
We studied the bladder cancer cell lines MBT-2, MB-49 and HT-1376, and the prostate cancer cell line PC-3 was used as a control. [Ca2+]i was measured with the fluorescent calcium indicator fura-2/AM. Bradykinin induced cell contraction was studied on only MBT-2 cells by taking microscopic photographs. Matrigel coated transwell chambers were used to test the invasive behavior of cancer cells.


RESULTS
Bradykinin induced a transient increase in [Ca2+]i in the 3 bladder cancer cell lines, which was suppressed by a specific blocker of B2 receptors, the B2 inhibitor. Bradykinin did not induce an increase in [Ca2+]i in PC-3 cells. MBT-2 cells showed a contractile response to bradykinin. ML-9, a myosin light chain kinase inhibitor, or W-7, a calmodulin antagonist, completely abolished this bradykinin induced contraction, although a bradykinin induced calcium transient was consistently observed. When bladder cancer cells were incubated with bradykinin, the number of cells which migrated through a matrigel coated filter was significantly greater than that of the control without bradykinin. This bradykinin induced chemo-invasion was completely blocked by the B2 inhibitor. Bradykinin did not evoke the chemotactic response in PC-3 cells.


CONCLUSIONS
Bradykinin can increase [Ca2+]i transiently in bladder cancer cells, which is mediated by B2 receptors. The contractile response of MBT-2 cells to bradykinin appears to occur as a result of the actin-myosin interaction caused by increased calcium. In addition, bradykinin can induce locomotory movement of bladder cancer cells through B2 receptors. It is difficult to explain this chemotactic response only by the calcium mobilizing effect of bradykinin.
Baba
K
K
Department of Urology, Fukushima Medical University School of Medicine, Fukushima, Japan.
Yamaguchi
O
O
D000818:Animals; D001920:Bradykinin / Q000494:pharmacology*; D002118:Calcium / Q000378:metabolism*; D002460:Cell Line; D002465:Cell Movement / Q000187:drug effects; D002633:Chemotaxis; D006801:Humans; D008297:Male; D051379:Mice; D018002:Receptors, Bradykinin / Q000187:drug effects / Q000502:physiology; D001749:Urinary Bladder Neoplasms / Q000378:metabolism / Q000473:pathology*
D018002:Receptors, Bradykinin; D001920:Bradykinin; D002118:Calcium