Strontium Chloride Sr-89

Strontium-89 chloride is a calcium analogue that selectively accumulates at sites of osteoblastic bone metastases through incorporation into newly synthesized collagen during bone formation. The biological mechanism of pain palliation involves both direct and indirect radiation-induced effects.
Direct radiotoxic effects of 89SrCl2 on prostate carcinoma PC-3 cells were comparable to an equivalent dose of 2 Gy X-rays. Indirect effects were investigated using MC3T3-E1 pre-osteoblast cells. Exposure to 89SrCl2 resulted in a concentration-dependent increase in prostaglandin E2 production by MC3T3-E1 cells, reaching approximately 175 percent of control levels at the highest concentration tested. This PGE2 response was not observed with X-ray exposure either in the presence or absence of stable strontium chloride. Interleukin-6 was subsequently produced by MC3T3-E1 cells in response to 89SrCl2 exposure via a PGE2-mediated pathway. These findings demonstrate that 89SrCl2 induces the release of potent biochemical modifiers of bone turnover, suggesting that pain palliation results from a complex interaction of direct tumor cell radiotoxicity and indirect radiation-induced effects on bone cell populations.

Fig. 1 Interleukin 6 (IL-6) production by the MC3T3-E1 cells upon exposure to 89SrCl2/SrCl2. (Davis J, Pither R J. 2001)