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Raman spectroscopy of bone has been used to characterize chemical changes occurring in diseases such as osteoporosis,
osteoarthritis and osteomyelitis. Metastasis of cancer into bone causes changes to bone quality that are similar to those
observed in osteoporosis, such as decreased bone strength, but with an accelerated timeframe. In particular, osteolytic
(bone degrading) lesions in bone metastasis have a marked effect on patient quality of life because of increased risk of
fractures, pain, and hypercalcemia. We use Raman spectroscopy to examine bone from two different mouse models of
osteolytic bone metastasis. Raman spectroscopy measures physicochemical information which cannot be obtained
through standard biochemical and histological measurements. This study was reviewed and approved by the University
of Michigan University Committee on the Care and Use of Animals. Two mouse models of prostate cancer bone
metastasis, RM1 (n=3) and PC3-luc (n=4) were examined. Tibiae were injected with RM1 or PC3-luc cancer cells, while
the contralateral tibiae received a placebo injection for use as controls. After 2 weeks of incubation, the mice were
sacrificed and the tibiae were examined by Raman microspectroscopy (λ=785 nm). Spectroscopic markers corresponding
to mineral stoichiometry, bone mineralization, and mineral crystallinity were compared in spectra from the cancerous
and control tibiae. X-ray imaging of the tibia confirmed extensive osteolysis in the RM1 mice, with tumor invasion into
adjoining soft tissue and moderate osteolysis in the PC3-luc mice. Raman spectroscopic markers indicate that osteolytic
lesions are less mineralized than normal bone tissue, with an altered mineral stoichiometry and crystallinity.
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