Detection of an inhibiting activity for osteoclast bone resorption from human prostatic cancer cells

An inhibiting activity for isolated osteoclasts and bone resorption was demonstrated in culture supernatants from androgen-independent, but not androgen-dependent, human prostatic cancer cell lines. It causes a dose-dependent osteoclast inhibition as quantified with a bone resorbing pit formation assay. The constitutively released activity was determined to be protein (>50 kDa) distinct from some of the known cytokines in bone resorption. The activity does not affect osteoclast morphology and viability. Time-lapse video microscopy revealed an osteoclast motility increase, disrupting their anchorage to the bone and resorbing processes. The association of the activity with androgen-independent cancer cells that disrupt bone remodeling is discussed.